Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Navy - Military - Battleships: => Topic started by: Harrison on November 21, 2009, 10:13:19 am
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Hi,
As the title suggests, I am building a 1:28 scale Hamina Class Missile Boat.
Unfortunately, as I am an 80's child I am not satisfied with 2 channels of scale action. I required a little more from this most recent build, I also don't have massive amounts of time to spend on detail. I found that on most previous builds the detail dragged out and in some cases was never completed, I needed something with very little detail and a large gun relative to the size of the boat.
After several weeks I found the Hamina Class Missile Boat, there are only 4 all serving with the Finnish Navy and based out of Upinniemi (Finland of course). Most info about the boats can be found here http://en.wikipedia.org/wiki/Hamina_class_missile_boat (http://en.wikipedia.org/wiki/Hamina_class_missile_boat)
What I am doing may seem a little extreme, I don't know as I have not come across anyone else doing something like this. Maybe there are others on the forum doing similar work, if there are then I would very much like to meet up and share this interest.
Anyway, less of the speal and more about the build.
As all the real complicated unknown engineering as far as I could see was based around the Bofors Mk111 57mm I decided to approach that first.
It really was a case of starting from the ground up, I had a few ideas of how it was going to work but nothing really solid. Fortunately for me I am an engineer (Electronic and Mechanical) so I have access to several software packages which allow me to produce designs and physical hardware from those designs, this made getting a few concepts modelled and simulating relatively inexpensive.
it doesn't take too long of cost much to make parts in plastic so this was the medium of choice, I had to select a projectile which of course meant that the barrel was going to have to accommodate the round and could end up not being to scale but I figured it's only one barrel. As long as everything else is to scale then it doesn't matter.
The MK111 has both rotation and elevation which I needed to recreate reliably and proportionally, I decided to go for 2 x 1:150 Micropile motors from www.cornwallmodelboats.co.uk (http://www.cornwallmodelboats.co.uk) to drive both azimuth and elevation coupled with potentiometers (just like a servo motor). This means I can get precise repeatable positioning and accuracy, they are also very small so plenty of space for all the other gubbins.
The MK111 also fires at 4 rounds per second, this also seemed like a difficult challenge. I know you can get electric BB guns firing at faster rates but to be honest plastic BB's aren't going to cut through ply and balsa!
I needed 4.5mm Steel BB's, 4 or more rounds per second at air pistol power in a super small space. After a few days of head scratching I came up with a design which I felt was a good starting point, here is a picture of the internal design of the first prototype and progress up to the current form which is pretty much ready for the electronics controller PCB which controls all motors, firing, CO2 temperature monitoring and coolent(warment) flow, rate of fire, power of shot, round store level and monitoring motor current.
I'll update as I go, I'm close now to moving on to the Hull which is Aluminium with composite everything else.
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I'm using a couple of Graupner Jet drives (aluminium of course) as the full scale boat uses these, also great for transporting as you don't have props and rudders to trash in the car of at lakeside!
I've put my Mini-Z next to them in a photo so you can get an idea of the size, the boat is 1800mm long so it will need some serious power. They will be driven with 2 Hacker A50 S10 brishless motors on six Li-Po cells, I am designing the speed controller on tot he main control board for the boat.
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I've used 4.5mm BB's for the Barbette bearings as I had a few kicking about, there wasn't really much space up in the gun for custom bearings using this BB so I opted for some nylon ones instead.
You may have noticed the big white gear on the side, this is part of the auto feeder.. When 10 shots are fired from the hopper in the main gun body, the gun will tip back and line up with the feeder output. The feeder motor will then run until the magnets pass over the reed switch 10 times, the gun will then return exactly to where it was before reloading.. I will just need to select the number of rounds and power for that fire.
I had noticed that after about 6 shots the CO2 cylinder gets very cold and power drops off, I've come up with an idea of running the motor/speed controller cooler pump backwards... Normally the water will come in via the speed controller then motors and finally through firing valve metalwork, with a few one way valves when the pump is run backwards it will be in a closed loop and when the temperature reaches a set point the speed controllers will run two of the motors coils so it will warm up but go nowhere thus warming the CO2 parts.. At least that's the idea.
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I found a few more pictures of the Bofor build.
I had a 1:62 small is motor which I used to test the azimuth drive, worked very nicely. The barrel shown was temporary, the stuff you get in the model shop has an OD of 6mm but an ID of something like 5mm so not a snug fit for BB's. My local tunring firm cut me a length of 6mm OD 4.5mm ID stainless seamless tube which was perfect.
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I've used magnets in the feeder so that the balls get picked up one at a time and carried up then pushed through as there is a wedge just behind the magnet, difficult to explain in words but I think you can see in the photo what happens. The feeder holds about 65-66 BBs with 10 or so in the hopper.
I'd just like to add, in case there are any 'Jobsworths' out there (people who iron there underpants and would shop their grandmother for not paying her poll tax), yes the barrel is less then 30cm. The boat however is 180cm, thus exceeding the 60cm legal minimun for air weapons under 12 ft lbs. As the maximum that it is capable of is 5 ft lbs and I am well over 17 years of age it is not a firearms contravention.
God, I can't stand people who try and stop others from having fun!
Anyway, that's my moaning out of the way.. Back to the build.
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I've just finished milling the the last motor drive gear for the gun, apart from the out skin (which will be painted solartex) that's pretty much it.
I'm now moving on to the PCB layout.. I did the schematic last weekend (circuit diagram) and hopefully I'll get the layout done before Monday, I usually get a few circuits made on a panel as it's a standard price for a sheet about 1.5 x A4.
Probably a few weeks away before I have full motor and gun control as it takes 10-15 days to turn around PCBs, I could do it all on veroboard but it would take hours and you only have 1 each time.
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I'm not knocking standard remotes but there usually isn't any two way comms which isn't good if you have things like motor/speed controller temp, active radar, fault reporting etc..
I came up with my own design of remote which returns the data I need and has unlimited channels/functions, I'm currently doing the coding(software) for a colour display which has a bit more area but this one works ok for now. It's 433MHz.
Please excuse the rubbish phone camera photos.
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Fantastic O0 :-))
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I'm not knocking standard remotes but there usually isn't any two way comms which isn't good if you have things like motor/speed controller temp, active radar, fault reporting etc..
I came up with my own design of remote which returns the data I need and has unlimited channels/functions, I'm currently doing the coding(software) for a colour display which has a bit more area but this one works ok for now. It's 433MHz.
Please excuse the rubbish phone camera photos.
Splendid work there! I'll be enjoying your progress reports with much interest :-)
I'm interested in what solution you have found for two-way data communications? rfPIC12F675F (would be at that frequency range) or something else? How much data rate you are having?
Cheers,
^Jani
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Hi Jani,
I'm using chipcon CC1000 transciever chip with PIC18F46K20 micro running things, boat side the micro is 18F26K20 with a mac approach using a bus and separate micro for each main system. The rate is set to 9600 to keep it reliable, not a great deal of data is coming back.. Going out is a check packet to make sure it doesn't go out of range or carry on if data is lost, also the joystick position(if changed) confirmation is sent back on each command.
The radar will be using a camera and laser with line filter, depending on the position of the line with reference to the center of the image it will calculate the range to target and direction.
I'm quite a way off that bit just yet but the idea will be that the boat can be set to fire on any targets that come in to a set radius.
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Really interesting how you're building the gun. Congratulations!
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I've just finished the PCB layout for the gun which is quite exciting.
I had planned to use a brushless motor for the azimuth drive which would mean no need for a pot but I couldn't find a geared one small enough, as I didn't leave a contingency for this it has left me with a minor issue in that I need some method of precise position measurement.
As there is no place in the center of rotation and I can't use linkages or couples because of excessive play I have had to come up with something else, I am planning to use microchip mTOUCH capacitive sensing in a 180 degree arch mounted on a ring PCB suspended under the Barbette, I've ordered a dev kit which should be with me on Tuesday but it means I'm probably about another 4 weeks away from azimuth control with feedback :((
It does mean that I may have to have a funky touch sense on/off button somewhere on a face of the composite superstructure!
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As it took 3 main bodies and 5 wheels to get the design working nicely I figured that I should post a close up of the final feeder design, below are a few previous parts which didn't quite make the grade.
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This is the current state of the gun, I have Azimuth and feeder control along with coil (which has been working for a while). I need to wait for the PCB before I have elevation control as I am using the PCB as the motor mount, I will try and get a google video account sorted out today as I have a video of a test fire to post.
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Cracking stuff - very good indeed.
Andy
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Ok, so I've created a YouTube account and posted a test fire 5 shot rapid fire. This is about the fastest possible rate (1 shot every 150ms), I think it's a case of BB's getting pushed upwards in the hopper and not coming back down before the next shot is fired. The magnet helps a lot as it keeps the next round in place and then pulls it down in to place sharply when ready.
http://www.youtube.com/watch?v=cL8wjKh9ZMM (http://www.youtube.com/watch?v=cL8wjKh9ZMM)
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Goodies arrived today, I've got two different mTouch (Microchip cap sense) development boards which I plan to use to develop the barbette ring PCB for azimuth positioning. I think that I will also need to have a nice on/off button somewhere on the superstructure.
The panel on the right is based around a PIC24FJ256, which I think will be the one chosen option but I will know for sure after some playing.
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Great stuff, way above the average modellers skills but could be the future we are looking at, keep going. BTW Harrison ,are you into robots by any chance?
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Wasn't there a movie in the 70's called "robot love slaves"? I suppose, it would need to look very human like though.
I could switch her off or maybe turn down the volume if she starts going on about something uninteresting!
I'm only kidding of course, I started to make a tracked robot which is still in progress pending some camera work I am currently doing. This is the same camera which will be doing the radar and auto aiming stuff, it takes ages to do the software which is processing the image and there are only 30 hours in a day.
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No no no, I dont need one of them ! The Lady Muriel (the wife) has been mine for over 49 years , oh er, hmm nearly 50 , think I`m in trouble. The reason i ask is that someone is trying to start a robot-wars type event for boats. Any interest ?
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Only if projectile weapons are allowed, it would be a bit silly to see boats with hatchets making a mess on the lake!
Sign me up if it's guns, missiles and depth charges!
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I believe the film was Cherry 2000 with a very young Melenie Griffiths - but I don't think it is on her CV. Awful movie.
I have been following this for the last couple of days drooling at some of the stuff you're doing. Love the work man, please keep it going. Where will this beast sail? I would love to see it when it is done.
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There are a few lakes nearby which may get to see her, I run my other two boats occasionally down in Newhaven. It's fairly flat once you get in past the defences and there is plenty of space... I'll probably look out for a club in East Sussex once she is ready, it will probably be another 4-6 months before she's completed.
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That is a bit too far for me - I assume it will be u-tubed eventually?
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I will try and take images and video of everything as I go, I was thinking of doing some kind of promo trailer as per the full size version http://www.youtube.com/watch?v=MVih2G0TMBQ (http://www.youtube.com/watch?v=MVih2G0TMBQ)
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On to the capacitive barbette ring today, the reference design shows two chocks with a gound line beween them. I aim to simply create this in an arch over 270 degrees with the chip and other components in the other 90 degrees.
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After some time with the cap sense dev kits I can see some potential issues with accuracy, it does seem to be influenced slightly by outside forces unlike potentiometers. I'm not so sure that I'd like it aiming the gun so I've been coming up with other ideas, this has probably been the most drawn out issue so far and any solution needs to be very accurate.
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Accurate measurements can be obtained but its a bit demanding on the processor, there are so many other things that the system needs to be doing so reading the azimuth position should be a simple few milliseconds affair.
I think I will still use it, I do like the idea of an on/off switch/button which is not effected by the elements (like water and dirt).
I've come up with the concept of having another wheel (of equal diameter) as one suspended under the Barbette, the idea is that there will be a fishing lie pulley type system so that as the Barbette rotates as does the other wheel (which I think will be just under the deck in from of the gun. This will be directly connected to the Potentiometer, the only issue being that there will now be an additional 3 wires going from what would be a fixed point on the boat to somewhere which is moving as I can see over time the wires breaking.
I've planned for this anyway and included a pull up resistor on the input line (1M Ohm) so that in the even of any of the 3 wires breaking I will be able to detect the error and report it via the remote control.. for example.
If the ground wire breaks the input will float up to supply (3.3V) which it would never normally get to, likewise if the +v wire breaks the input will read 0V.. Another abnormal reading.
On a different note, the camera development kit arrived over the weekend, this will form the radar element using a laser line. It's several months away yet but I thought I's post a picture of it.
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I was considering designing in my own brushless speed controller but as I can achieve the same results using controllers I have decided to use the two I picked up whilst I was in Hong Kong a couple weeks ago, they are 125A which should be enough to run my 2 Hacker A10S motors.
They are specifically marine with water cooling so no messing with potting my own which would almost be part of the main PCB so not desirable, only 750HKD each which was hard not snap up.. I would seriously consider a trip if you a keen modeller, they have pretty much everything in the R/C model district from static models to helicopters and everything in between.
Today I am going to try and design the wheel idea for the azimuth positioning, this is the last mechanical aspect of the gun to be completed so once the PCB arrives next week I should be able to start writing the software to control it.
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This is what I have come up with, this part of the deck will be removable for servicing the gun which also makes it easy to bench test, the gun deck part will sit flush with the deck and screw down on to a rubber seal which runs around the underside inside the fixing screw holes.
I will use fishing line and a single spring (to keep the tension), luckily there is a box of some type on the deck around where the pot is mounted so I am going to make that part the same as the break which sits in front of the gun.
You will notice a channel which runs under the break, this is for the wires from the Pot. It all needs to be tighter than a ducks bottom.
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This looks really, really cool! I'm looking forward to seeing more of this project - I would love to have a working gun and radar on my boat!
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I'll make sure as much information as possible is available to anyone wanting to create something on their own boat.
I just broke my last 2mm End Mill so no milling until some point tomorrow so I've decided to move on to the remote MK2 for now....
I picked up a cool little PCB mounted joystick in china a few weeks ago, I'm still not totally sure which one will go on but as you can see they are both pretty small.. This is a pound coin for anyone outside of the UK.
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I've gone for the flat joystick as it has a smoother action, here is what it's going to look like.. It will take 4AA cells either alkaline or rechargeable via USB (which will also be used for downloading mission data)
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I started the PCB layout yesterday, I had pretty much already done the schematic (circuit diagram) over the last two weeks.
I've been giving much thought to what functionality the boat should have and for the controller I have come up with the following for the controller:
160x128 full colour TFT display
5 button keypad for menu navigation
Proportional joystick (2 channel)
Sounder for warnings etc..
Vibrator in case I can't hear the sounder
USB (Mini-B) for charging and downloading mission data
433MHz 2 way RF comms
4 x AA power
Temperature sensor
All the boat data will be displayed on the TFT using different modes.. It will have things like:
Battery voltage (pack1/pack2)
RF signal level (both boat and remote)
Battery temperature (pack1/pack2)
Motor temperature (motor1/motor2)
Motor current
Radar data
BB's remaining
Set rate of fire in rps
Set power of shot in fps
Missiles remaining
Depth charges remaining
Depth charge timer in seconds
I'd be happy for any inspiration at this stage as I wouldn't want to miss anything which would be nice to have.
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I finished the PCB layout today for the Remote and sent the files off (along with the gun controller) on a 5 day turn around so I should have some nice shiny new PCBs on Thursday at some point, the end mills arrive this afternoon.. A little late so no parts today, I'm pretty busy over the next few days so I'm not sure how much will get done.
I expect to the have the Azimuth positioning sorted out by or on Saturday so that will probably be the next big update.
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I really just don't know where I get the time!
I've got all the important bits milled for the Azimuth positioning pot, I will now make a mock deck that I can clamp to the bench...
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I can't find any fishing line anywhere, really quite annoying.
Lucky for me I have a fishing tackle shop on my street, it would be even better if I liked fishing!
Anyways, on to the mock deck.
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I'm turning green with envy for every post you make, keep up the good work!
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I've modelled what I think should do the job, it needs to be water tight so I've incorporated a seal that runs around outside the screws (which will have rubber washer seals. I will probably make a mould for the big seal and use silicone.
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Just milled the middle of the three parts which are shown above (the top part being the mock deck), this bit holds the seal and the gun deck sits on it flush with the deck.
Tomorrow afternoon I should be able to mill the part below (which holds the nuts), I was going to tap the plastic then thought 'it's going to be on and off quite a bit so metal nuts are needed'.
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I've purchased some 'braid' from the local fishing shop, it is also used for fishing(so I am told) but seems to have attributes better suited to what is needed, the breaking weight is 18lbs.
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I failed to mention that it workes perfectly, the smallest bit of rotational movement is transfered to the other wheel without any loss.
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Just finished the gun deck mounting/seal system, it all fits together very nicely. I have left 0.5mm all the way around so it's not too tricky to get in and easy to line up the fixing screws, once the PCB arrives on Thursday I will be able to get the elevation motor fitted and that will conclude the gun mechanics.
I'll order some solatex over the weekend but leave covering it until it's had a good few weeks of good testing.
I suppose I should get on with the hull and superstructure design, my milling machine table area is limited to about 300mm x 400mm so I will probably have to make my bulkhead spacings 300mm as my deck sections will of course be cut on the machine.
The bulkheads will be waterjet cut 5mm or 10mm aluminium with aluminium sheet panels which will be welded to the bulkheads using easyweld or some low temperature welding product.
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Yer a flash git! I know that much.
This is very nice work - I look forwards to it every day.
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I try!
Been thinking about the hull quite a bit, I don't want to get it wrong yet there is little data available other than the drawing sent to me by Akers Finnyard. It is of course very nice and offers better detail than anything available on line but It don't give me very good hull profile data, a 3D model of the actual hull would be the ideal solution....
Maybe some time should be given for trying to get hold of this data!?
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I'll order some solatex over the weekend but leave covering it until it's had a good few weeks of good testing.
Solatex is horrrrrrible, try Profilm :-))
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Does it have a similar thick matt type textured finish?
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Should imagine so, I've only ever used the shiney stuff but I expect you can get some matt.
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The difference between solatex and solafilm is that the film is shiny, thin and quite fragile(it will rip easily), solatex is much thicker and more like fabric. It is very tough compared to films.
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hi harrison
your project is superb exactly the type of thing i love. if you sail in newhaven i guess your fairly close to me i'm in tonbridge, west kent
when it's finished make sure you come visit the cygnets mbc in mote park maidstone.
phil
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Hi Phil,
Thanks for the offer, I will surely be looking for places to sail the beast and inland lakes are preferable. I am quite a bit closer to you than Newhaven (about 25 minutes) so perhaps I could pop up and check it out one coming weekend, when do you sail?
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best time is any sunday morning. location mote park maidstone. check out www.cygnetsmbc.com for more information. let me know when your going and i'll make sure i'm there
look forward to seeing it
phil
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To many posts without stuff to look at...
Here is the most up to date virtual model of the gun, it is as per the actual hardware.
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I keep looking at this 68ci fiber wrap paintball cylinder and thinking that I should be using it for the gun instead of the CO2 bulbs, I've definitely got the space for it but I would need to try and make a low friction seal which will rotate easily.
I think that a fixed hose would restrict the guns rotational movement, I would definitely get a lot more shots before the vessel gets so cold that the power noticeably drops off.
It would be a simple addition so something that I should think about when doing the bulkhead designs.....
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I'm not sure it's gonna sail!
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Please can someone pass the glue!
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It's all the clearing up I have to do at the end of the day which is the worst bit, sometimes the crumbs get stuck in the keyboard :-))
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I can see this bit taken a good few days to get right, I'm still unsure of the exact lines as the drawings I have (although very good) are not very detailed on the hull shape.. As much as I would like some better existing data, I may have to make a best guess and go for a design which looks right above the waterline and gives the best chance of getting it on the plane.
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That's enough for tonight, I'll try and get most the hull constructed over the weekend.
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Topic split... http://www.modelboatmayhem.co.uk/forum/index.php?topic=21169.msg205870#msg205870 (http://www.modelboatmayhem.co.uk/forum/index.php?topic=21169.msg205870#msg205870)
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I've done a bit more of the hull today, I'm now at the difficult part where the crease starts..
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Today I changed over to a valve with a bigger port size as I wanted to increase the power, I managed to get up to 152.9fps (2.74pds) before the valve stuck open... I've got another one on order which should hopefully be here tomorrow, I'd be gutted if the PCB arrived and I could fire the gun!
I've not really had much chance to do anything on the hull so far this week, that thing you have to do which pays the bills got in the way again. I'm hoping to get a bit more done tonight, I've ordered some Techno-Weld aluminium welding rods which will be used to weld the hull together (hopefully).
I'm still trying to figure out how the aluminium hull is going to mate up with the plastic deck and superstructure with a good level of accuracy, I've been up for a good hour each night trying to get to sleep over it.
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My man on the inside has really come through for the build, I have managed to obtain drawings of the bulkhead sections. This is really great news as my attempts at the hull design were a little more like Thrust SSC!
I'll get right on it tomorrow and hopefully by some time next week I should have something which resembles a hull, I'm undecided on sheet or strips of aluminium.. On one hand the sheets will require less welding but strips will be easier to bend an work with, I suppose I will have to see which works out easiest.
The welding rods are £22.50 for 10 and they are 250mm in length each so thats 2.5 meters of weld for £22.50, quite expensive if I use thin strips for the hull skin.
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No deliveries yet... I have started on the new accurate hull design, I've basically created sketches by tracing over each bulkhead drawing. I've had to scale them to 1:28 and I'm only doing half the hull so as to minimise possible errors induced by myself, it should simply be a case of doing a mirror copy at the end.
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About half way
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It was more like a 1/4, this is 18 metres of 42 so still not quite half way.
Still no deliveries <:(
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23 Metres, just over half way. I bet someone just hacked this hull design out of a piece of clay!
I have just had a very cool thought... I can remove everything above the waterline, assign the solid part the material 'Water' and it will give me the exact mass. I will then be able to see exactly how much weight I can have and where without it even seeing the lake... Sweet.
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At the 30 Metre point, I think a combination of thin strips and larger sheets will be required. I'm not sure exactly how just yet but I may be able to unwrap the skin at different points which could give me a template for cutting the aluminium, I suppose water jet would be the cheapest option.
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A bit more.
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Voila!
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A littel glimpse of whats to come.
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The new valve arrived about an hour ago, I've got it back on the gun an test fired.. All seems to be working correctly.
The PCBs have arrived... Here is a snap of the PCB.
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This is what it looks like on the gun, I need to populate it with components.. This I will do over the next few days.
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I thought that I may as well get it out of the way, it only took me 40 minutes.
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Amazing work, can this be moved to build masterclasses yet?
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I've just installed the populated PCB, just need to connect up the Azimuth pot and make a dummy master control PCB to act as the boats main PCB, this is because I've designed a custom type of comms buss where any system attached will have a unique address so limitless add-ons.
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looks realy good. just wish i knew what the blue blazes you are talking about! and what are you hoping to acheive, apart from a pest destroying boat!
colin
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Ever since I got in to boats I always dreamed of having a working gun, something that up to a couple years ago I wouldn't have had the understanding to do. I guess I'm just making up for lost time, or maybe I just want to do it because it seems pretty cool.. Actually I think it's both..
I've still got loads more to do on it and for me building it is the best bit, I am looking forward to destroying some model drug running Nikko speedboats!
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gets my vote, perhaps some of the RTR from the high street as well??!!
what program are you using for the Dwg's?
colin
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A TLA which I am not familiar with... RTF I know, is it Ready to Run?
I was sinking of something cheap from Maplins, sorry I meant thinking.
I'm using Solidworks for the 3D stuff.
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rtr, ready to run, or not, as is usual. from maplins more often than not!!!!
solid works, you made of money?
colin
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I've inserted some planes at 150mm spacing so I can create the bulkheads for the model, I've changed the view type which outlines the basic lines although the changes in surface direction are actually so shallow that you cant see them otherwise. This view makes everything a little easier to see.
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It's a work tool so I get to use it for hobby stuff also, there are cheaper (some would say better) packages out there.
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I have to say that this is the first time I have used lofts so a bit of a learning curve considering that the entire hull is made of them.
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Bulkheads... I think they are looking a bit solid though
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That's enough for tonight... Hopefully I can get the longways supporty bits in so it doesn't fall apart (anyone know what they are called?)
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Sweet, can't wait to see it built and sinking ships! :-))
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That's enough for tonight... Hopefully I can get the longways supporty bits in so it doesn't fall apart (anyone know what they are called?)
longerons
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That would have been my first guess!
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Fronttobackerons? Bowtosternablies? ...
I've already got me coat on.... :P
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or possibly stringers :-))
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I've had to backtrack slightly as I need a few Keelerons as my bulkhead designs will be effected by where I put them, I'm going for a keel and two either side. This should keep everything in place while the hull is constructed/welded, it looks like the hull panels will sit slightly high all the way around so the deck will sit inside and I can silicon seal it all the way around... I think pictures and progress will offer better explanation.
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I wasn't sure about having the Keelerons at the full length of the boat as the sheet of aluminium from which it will be cut will be quite big, but as all the bulkheads will come out of the same bit it made sense.
I've included the provision for the Paintball tank as I think ultimately the gun wants to use this over a small CO2 supply, there is after all lots of space.
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I've managed to send commands to the Gun from my dummy command PCB using the experimental communications bus, the gun is receiving the command as I can turn on and off the power/fault LED... For some reason I'm not getting anything back...
I am currently investigating this.
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Fricking computers! Blinking compiler is out of date and I am running unsupported beta version.... Very annoying!
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as before, wish i new what you were talking about.
have every faith in you
colin
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I just make it up as I go along
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Doh!
I have put diodes on the TX outputs from each device on the bus so that they can not conflict with each other (e.g. if the gun TX pin goes high and at the same time the main control board TX pin goes low then they will fight each other resulting in no comms and possibly damage to the chips), by putting diodes on each of the TX pins they can pull the RX bus line low but not each other..
I had forgotten that I am using an RF module on my dummy main control PCB... It of course has TX and RX pins, diode added there and all working OK, now I will start writing the software inside the microcontroller in both the gun PCB (as per the pictures) and the dummy main controller PCB which I have basically lashed together so that I have something for the gun PCB to talk to/receive commands from.
I hope to have azimuth and elevation movement by the end of the day, there will need to be a routine (section of software (also known as 'code')) which takes the current position (known by the reading from the POT (potentiometer) and then moves the motors until that POT reads what we want it to... For example: it's at 100 (about 9 o'clock) and we want to move to 12 o'clock, thats about 1500 on the POT...
We can't just start the motor then stop it when it gets there as it will almost certainly overshoot and to kick in the motor at full voltage would be bad for pretty much everything.. We need to take the motor from stop to full speed in about 500ms (half a second) then when it gets close to 12 o'clock then slow it down so nice and smooth, this then means a simple command of only a few bytes needs to be sent to it... HEY GUN, MOVE AZIMUTH, 1500.. which looks a bit like GAM<1500>
I'll try and explain as much as I can but if anyone doesn't understand anything and would like to then please ask, I will be happy to answer any questions.
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I seem to have a new problem, the gun PCB is drawing about 500mA. That's about 490mA more than it should be without runnings motors, I've isolated it down to the P-Channel FETS on both 'H' bridges controlling the motors. I may have put the wrong parts on the board or got the pins wrong when creating the PCB footprint for that part.
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"xxxxx".....
I would like to say that there should be some kind of temporary storage for text entered in to this field so that if the back button is pressed in haste due to the image attachment being too large it doesn't loose everything you have just spent 15 minute typing out!
I've managed to get the motor control routines working exactly as I would like with all possible parameters being easy to adjust remotely, I've only implemented the 'smarter' movement on the 'Elevation Upwards' part but it is a simple copy, paste, edit for elevation down and Azimuth clockwise and anticlockwise so that I will be doing next.
It's too easy to get absorbed in writing software and what seems like moments turns in to.. well.. half days! It's all in the detail..
I've got the reload working using a simple (run feeder for 0.8 seconds per BB required) routine but this is unreliable as the motor may be slowed by the random configuration and quantity of the BB's inside the feeder, this is why a reed switch is to be used which counts the times the disc magnets (holding each BB as it rotates) passes over the reed switch.
Here is a video of the movement, notice that the Upwards starts off fast and slows as it reaches it set postion, the downwards is at a set speed (slow enough not to overshoot)
http://www.youtube.com/watch?v=M2Oaj0qoSlE
This is an image of the current setup, you can see the 2 x 3 cell Li Po packs.. The other board is providing an RF link to the PC and supplying 3.3V from the 24V for the electronics and motors.
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Up and Down both working in harmony, now on to the feeder reed switch bit as that ties in with the reload which requires the elevation.
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Out of curiosity, I wonder what makes a thread 'New'?
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I like the other video of the rapid fire you have uploaded as well. :-)
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Many more to come, I'm just sorting out the reload so that one will be next.. Unfortunately photos don't really illustrate much of the work done in software.
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I've just got the reload routines working nicely using the reed switch to count in the rounds, as the hopper holds about 8 comfortably (the total amount is 'Top Secret').. Well, you do have to have some aire of mystery!
Where was I?
Oh yes... as the hopper holds about 8 comfortably I have set the reload point to 7 so when 7 shots have been fired it will reload.
I will also set a reload function just in case 5 have been fired and can a further volley of 5-6 rounds are required soon but not immediately.. This will reload what is missing from the hopper.
Anyway, here is the video clip.. It takes ages to upload these darned things.
http://www.youtube.com/watch?v=wqgE4pQaC8w
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I know this is taking some work - but have you given any thought to how to aim it?
Would be a shame to have such a cool piece of kit but not be able to put rounds on target.
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Hi Steve,
Indeed..
It was one of many night time thoughts, this is the plan.
There is going to be a camera on top of the boat either where the long range radar unit is located (360 deg rotation) or in the range finder above the bridge, this is going to do a few things.. Provide a view which will be displayed on the controller screen, use a parallel laser beam to determine range (the radar) and for guidance of ordinance... the gun and other things not yet covered, I have a laser output on the board of the gun which is switched on when a target is selected it will move to the same azimuth position always pointing down the barrel (considering the distance apart from the camera) then the fine tuning will be that the laser dot seen by the camera will be moved to the center of the screen (where I am aiming)...
The other method which will also be possible is that you could use a laser pointer which is pulsed with an encoded sequence (like Morse) which the camera will be looking for on it's radar rotations, once it finds it depending on which (Morse) code it is it will assign the gun and fire that many shots or release something else which I haven't covered yet.
As range is known and power/elevation is fully controlled, hitting the target every time shouldn't be a problem.
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I've got a few ideas for a hose BB feed system using a wheel with magnets to push them along the tube (a bit like a dialysis machine), this is good as it will not cause damage if there is a jam and allow an unlimited number of rounds to the gun at a rate equal to the rate of fire..
I've also been giving the gun part a few redesign ideas to try and get the maximum possible air flow from the valve to the ball without loosing any in actuating plungers etc.. Based on some testing with another valve and a BB in a similar piece of tube as my barrel I am seeing speeds of almost 3 times what I get with the gun...
I suppost the great thing about the way the gun is made (without glue) is that I can upgrade with new designs just by undoing screws and swapping over the bits.
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"As range is known and power/elevation is fully controlled, hitting the target every time shouldn't be a problem."
Oh yes, the mantra of gunners down through the ages. {-) {-) {-) {-)
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I'm 'aiming' for an 'accurate' recreation of the full size gun it it's functionality, a shame I can't have exploding rounds though.
I have to say that apart from really modern guns, there aren't many that have the electronics that this one does. There is going to be an accelerometer on the main board so as the boat rocks and moves the barrel will stay exactly where it should be, at leaset that's the plan.
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I've just finished populating (assembling) the controller board MK1, I've used an 'off the shelf' RF module just for now as I need a working remote to allow development of the gun. There is no magic inside the module so don't be fooled by the gold can, it's just a chip and a few other components not unlike others on the main board...
You can see the USB connector (middle left) and the vibrator at the bottom, it all fits nicely in the back of the case but some milling is required for the buttons, joystick, USB and RF connector..
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Here is the blank 4 cell case.
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And the display being used, it is a 128 x 160 pixel full colour TFT 1 and 3/4 inch
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I'm making quite slow progress with the comms, I've spent the last two days trying to get the exchange of data over the air fast enough so that the controls seems proportional like a standard remote but allowing communication both ways for handshaking (can you hear me, yes I can hear you, oh thats good to know, we're all happy then).
I can move the joystick and get the turret to move which I doubt will ever need to be done as its a 'go to' type system, but it's a good test for the boat controls as we can't have jerky throttling of steering.
I'm pretty Happy with it so far so I'm moving on to the display, you may have seen the rendering (computer generated drawing) of the remote a couple pages back.. I am hoping to get something like this on the display so I expect my next post will hopefully have some pictures, if it comes to it I could always try and get some of my Gran naked to break up the text.
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It's been a real pain trying to get the azimuth control working precisely, thankfully it's working well.
http://www.youtube.com/watch?v=8W7vJ0UzhGY
Here is a video clip of the movement, I'm sending two different position commands. One is middle and level barrel and the other is about 100 degrees to the right (some seafaring types refer to it as starboard) aiming up, the accuracy is about 5.8 points per degree.
I think I have the following correct (I'm sure there are some super whiz maths peeps who may wish to correct me if I am wrong, which would of course be appreciated)
The range of 10 metres or 10,000mm gives a circumference of about 2 * PI * R = 2 * 31,416 = 32,432mm
32,432/ 360 = 90.08
90.08 / 5.8 = 15.5
15.5mm over 10m is pretty good, thats a 116 holes down the length of my boat...
At 30 metres it would be45mm
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Done a bit more controller work today, I've got some graphics up on the display. The colours don't show up so well with the camera as the blue looks light and washed out but it's actually deep and vibrant.
Going to get some text up next display the vitals like voltages etc..
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The range of 10 metres or 10,000mm gives a circumference of about 2 * PI * R = 2 * 31,416 = 32,432mm
32,432/ 360 = 90.08
90.08 / 5.8 = 15.5
15.5mm over 10m is pretty good, thats a 116 holes down the length of my boat...
At 30 metres it would be45mm
Its probably me, but where does the 32,432mm come from ?
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Indeed, I think everything needs doubling.
It's 30mm at 10m
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6cm at 30 metres
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Okay fella - I think you're having conversations with yourself again.
I understand some of the working out but I think you have explain some of these numbers in crayon - for the likes of me.
Are you talking about the degrees of rotation and what they translate to at a distance of 10m from the vessel?
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I was working out the distance between where rounds would theorytically hit based on my rotational steps, I have 1024 steps in about 200 degrees...
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Reckon its about 36 mm at 10M
2πr=2x3.146x10,000=62,832
62,382÷360x200=34906,666
34906,666 ÷1023gaps=35.930
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That looks about right
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Thank god for that, the grey matter must still be working. ;)
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I'm still trying to decide on a layout that looks ok and shows all the immediate stuff, there can be different screens for different modes. Cruising mode would have speed, battery voltage, motor and speed controller temperature. Weapons mode would have rounds left, power, rate of fire, radar etc..
It's a shame that the colours don't seem to show up with the camera, the green looks just like white :((
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I have not managed to get a great deal over Christmas and New Year, it has been mostly work done on the remote control.
As I didn't want a clunky on/off switch I connected the enable pin of the regulator to the microcontroller and the key pad so that it can be switched off by the micro and on by holding down the middle keypad button, I've also started to add icons to the display for the menu.
As things like brightness, volume and other stuff I have not thought about yet need to be adjusted there needs to be a menu to do it.
I'm hoping to get more of the hull done this week/weekend and do a test fire of the gun on multiple targets.
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This is fantastic...you will have to incorporate this technology in a ship like the Hood!!!
Can't wait for the next installment.
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I am happy to share the knowledge.
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Here is a video of the first multi position test fire.
http://www.youtube.com/watch?v=ynbmfJPnOLU
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I've decided to get a bit more hull work done this weekend.
As Graupner weren't very forthcoming with design files for their jet drive units I've started to model them, as this build is 'glue free' I need to make sure that everything fits together with machine screws perfectly, I expect another 2 hours and I'll have the whole thing modelled and ready to float in to the virtual hull.
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I don't know if anyone else lost thier sky due to snowy dishes, I had to fill a bucket with hot water and use the jetwash to melt it off. Extreme conditions require extreme measures!
In and around all the sledging I've managed to model the rear nozzle, I had overlooked the 5 degree down andgle of the prop and shaft which I have also sorted.
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Just the bucket left to do, it shouldn't be too hard as its all easy to measure with the caliper. I should have it done at some point after lunch.. Hopefully.
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What software are you using for the CAD work?
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Hi reefrich,
It's Solidworks
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I've just finished the Igloo, more pictures tomorrow when the light is better... Oh yeah and that drive thingy
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I've just floated the drives in to the hull, I still need to hollow out the rest of the bulkheads which I'll do next.
Both drives are now 1.5 degrees rotated inwards at the top, I'm not sure exactly how this will effect the handling. It does seem like it will help rotate the boat when going in to a turn which I think will be a good thing.
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Unfortunately I've left the Hacker A50 at work and as there is still quite a bit of snow blocking my car I'm not going to be able to design the motor mounts, I will however have a go at the couples.
I've seen on something in the past a coupling which uses two steel parts (Motor and Drive) which were connected by a flat spiral like disk, it didn't give the flexibility of a universal joint but I expect to have the motor pretty well in line so I'm only looking to reduce the noise and compensate for any small tolerances.
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I'm pretty confident about the coupling design, it will use 0.5mm copper. I think I have some laying about the workshop, it's pretty easy to CNC cut.
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Now I just need a motor or two.
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A pair of big grunty muthas - to shove that beast across the water. YEAH!
Ooops sorry, did I type that?
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Those types of coupling are horrendous, they used to be used for IC.
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I've left plenty of space for alternative methods, I wanted to avoid stuff like rubber
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There isn't going to be movement like an IC so hopefully they should be OK, I guess I'll find out after some testing. What other methods do you know of that I might be able to use or improve on?
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I don't like that type of coupling either, they are prone to imbalance, wear, noise and loosening up.
Have a look here for a few more designs: http://www.huco.com/products.asp?cat=46 (http://www.huco.com/products.asp?cat=46)
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These are great, thanks. I expect a of these are cheaper that machining 6 custom parts.
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The best coupling I've seen uses a round piece of rubber encased within the two halves of the coupling. I think they were made by Kalistratove. I don't think you'd be able to buy one anymore but they look like this:
(http://i288.photobucket.com/albums/ll184/andyn_01/Untitled-3.jpg)
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I expect a cross in place of channel would allow movement in all directions, it could be encased in rubber like those.
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I would have liked to purchase 2 couplings from Huco but they don't seem to do a 7mm coupling, as this is the diameter of my shaft I would like it to be a snug fit with set screw on the shaft flat.
Perhaps one solid piece and a few minutes on the band saw?
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how about some of these they can be bored out easy.
http://www.arceurotrade.co.uk/Catalogue/Stepper-Motors/Oldham-Couplings
Peter
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these is also these metal ones from
http://www.prop-shop.co.uk/index.php?id=26§ion=store&sub_section=products&product_type=26
what are you using for props in your jet units ?
Peter
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My local engineering firm are pretty good for turning, I expect they can do the cuts without too much trouble.
I've gone for the 'all in one' type coupling which you would think will go the distance, getting them made does also mean that both ends can be the right bore.
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My local engineering firm are pretty good for turning, I expect they can do the cuts without too much trouble.
I've gone for the 'all in one' type coupling which you would think will go the distance, getting them made does also mean that both ends can be the right bore.
getting the correct material is going to be the problem a lot of research goes in to them I have read as just 1deg will cause bending and metal fatigue , its the same as bending a bit of metal back and forth but 30000 times a min ..
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I was going to use stainless, I was hoping for an M5 set screw. I suppose I could bore them out.
I've made a start on the parts of the bulkheads which the longerons fit in to, the hull is the only part which will see 'non serviceable' assembly methods (welding).
I plan to tac each one in place then fit the panels to the outside and weld them from the inside using Technoweld rods.
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I've finished all the longeron slots in the bulkheads, I think I have an A50 in my spitfire in the shed. I can't remember if it's an A50 or an A60, I do know that it's very cold out there!
Perhaps a coffee and some warm clothes are required.
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Military [naval applications] use flexible drive couplings with thin mechanical wafer shims that flex.......so....... the resultant TIR [total indicator run out] between mating shafts is ZERO. ZERO..... {-) 0.00 .....surprisingly these are also used in our Collins Class "noiseless' submarines......... <*< ......Derek
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Thanks for the gen, I'll see what else is about before getting anything made... Silent would be nice.
I've just finished modelling the Hacker A50-10S, my poor spitfire..
Now on to the mounts.
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It's starting to look like a boat.
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Been super busy lately with work so I've not had much chance to get a great deal done on the boat.
I've just finished doing the notchy things which secure the longerons to the bulkheads (feel free to point out any terminology that I may have missed along the way), I'm not sure what to do next as there are so many things to do... Perhaps the servo trays for the jet drives...
Thinking that the more control the better.. I'm going to a servo per side to steer and a servo per side to control the bucket for forward/reverse, the idea here is that with independent motor control an element of sideways maneuvering is possible (at least thats the thinking behind it).
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Ah.. Yes, engine mounts may be a good place to start as the servo trays are going to be somehere nearby..
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Just on the subject of couplings, Kehrer seem to use Robbe or VERY similar which are available up to 6mm. The advantage is that there' plenty of meat for the grub screw to hook into.
Just a thought.
Tony
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Hi Tony,
Thanks for the info, I will check them out.
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I'm making a bit more progress on the design today, I've pretty much got the motor mounts finished which only uses 2 x unique parts (well three if you count the aluminium servo mounts that I have a box of).
I have made them adjustable just in case I am a few tenths of a millimeter out, they want to be perfectly in-line with the drive shaft on the jet drive units.
Servos and linkages next for the drive, any ideas for getting servo arms outside without letting any water in??? Think 5 meters underwater, so I guess whatever submarines use.. Any suggestions would be great.
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Looking fantastic :-))
GA7A should be what you're after:
http://www.prestwich.ndirect.co.uk/hdwraccs.htm
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Thanks, I don't suppose you have one of these do you? I could do with the measurements.
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I called PMB, it's a 10mm hole and the rod end is 1.5mm.
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Thanks for the feedback, it's great to see that people are interested and following progress.
I'm hoping to get the design of the main hull and superstructure ready for sea trials this summer, I'll have to design plenty of mounting holes inside for all the other stuff yet to be developed.
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I've traced the photo on the PMB website site and scaled it to the 10mm neck (10mm hole according to PMB) then modelled the bellow, It's looking a little tight on space.
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Harrison........certainly your CAD or Inventor skills are great :-))....but I am still unsure if you have resolved & decided on a 'commercially available' motor + drive coupling
Electronic design is fine :}....but some where you must nominate actual components as a building block to enable a real mathematical & physical understanding or scenario of your build to be established ........ O0 Derek
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I have modelled a commercially available coupling, the motors are Hacker A50 10S and the mount I am making from 2.5mm sheet aluminium.
I'm never really too concerned about parts being 'commercially available', if there is something which does not already exist.. I will design and develop it.. Like almost every part of everything that I have designed and made for consumer applications including injection moulded parts, I have a CNC machine which can machine insert mould tools and a small hand injection moulding machine. I try to avoid using it as its quicker to mill plastics or aliminium.
I have modelled the MG995 servo and floated it in to the assembly
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love youre adjustable motor mounts, however, adjustmets on the side, up against hull! defeats the object.you might think about rotating the mounts 90Deg so you can adjust from above. youre motors are going to be spinning at quite a few revs so alignment will be important. best to make it as easy as possible. i have used the Kehrer shaft/motor connectors on a fast reving motor and work fine.
all the best, have fun with lofting
colin
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Hi Colin,
The mounts need to be at this angle, as this is the rotational alignment which could require adjustment due to minor tolerances in the jet drive model. There isn't much access to adjust them so it will be ring spanners on both bolt head and nut (which will be in the inner side near the coupling).
The mounts will be bolted to the bulkhead with couplings screwed to the jet drive shafts, the motors then slid on the couplings and pushed up until the moving part of the motor mounts sit flush against the motor face which has the fixing holes. Once in place the screws Will fix the motor to the mount and (with the boat in a vertical position) the mounts fixed using the bolt/locknuts, the motors will then be perfectly aligned to the driveshafts and fixed in place.
Development and testing comes after the design phase, like with the Bofors Mini MK111
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could you not use a rivetnut or hankbush on the outside of your mount and then a socket cap setscrew from the inside, as a sheetmetal worker it makes more sense to me than trying to use to ring spanners in a confined space, you'd only need an allen key.
Unless i've missed something could you also explain why 3 linkages per side through the transom? do you not only need to control the reversing bucket? steering being achieved by independent motor control.
This is such cool project i wish you well with it.
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Thanks for the advice, that sounds like a pretty good idea.. Perhaps I could some how captivate a nut on the outside and use the Allen key bolt from the inside..
I think the difference in maneuverability between just using motors and turning the drive units will be quite significant, also I plan to control them independently as well as move the nozzles to get some sideways movement.
We shall however see on testing.
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this may help you, you drill the correct size hole then pein the spigot down, viola one captiv fixed nut. used them for the last 30 years, no problems.
http://www.rivetwise.co.uk/productrange/hankbushhex.htm (http://www.rivetwise.co.uk/productrange/hankbushhex.htm)
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Don't know if it's relevant to this hull form, but there was some photo evidence on other vessels with twin jet drives that there were shallow fixed fins on either side of the drives to reduce the crabbing effect that could occur. I know they are present on both USCG and Finnish 45 ft boats with the Rolls Royce KaMeWa units, but I'm not sure that is applies to Hamilton or other units.
You've probably got this covered anyway.
Tony
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Model bellows look very untidy and terribly out of scale on most model boats Harrison and they look terrible after a
while with all the gunk they collect from the lake. I like the Robart ones, with your skills, I'd wager you could do
much better than bellows
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Very true what Martin wrote. Have you got the space on the transom to reverse the bellows and have them on the inside?
Or could you use Bowden cables through greased polythene tube for the steering?
Tony
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Hi Tony,
yes, these look great.. I guess petrolium jelly sits nicely in the grooves..
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Does anyone know the length and width of the Robart spars, also the hole size for the fixed part?
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Well, it's been more than a month since I have been able to do anything on the boat :((
Work has been quite demanding of my time.
I'vce ordered a set of Robart spar thingys to measure off and hopefully I'll be able to model them in to the design over the next week, if I get some time away from work that is.
I'm still aiming for a hull water test run this summer...
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subtech do a nice line in water proof seals for control rods. basically a turned brass cylinder with a o ring inside. work for subs, very tidy.
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any news, hows it going or not?
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Hi,
I look at the gun on my desk every morning and I can't wait to get back on to getting the hull finished, I'm quite bogged down with work at the moment but things are looking a bit cleared towards the middle of next month.
I have some waterjet cutting that needs doing pretty soon so I will try an coinside that with having the hull bulkhead designs ready for cutting.
Thanks for keeping track of my build
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It does feel good to get back on to the build, I would very much like to see some sea trials of the hull this summer.
Thanks to Martin for the info on the 'Watertight Output Bushings' so Robart call them... Whats wrong with 'Plastic Pushrods' or 'Plastic Bellows', anyway, only Robart knew what I was talking about and I've got some on the way... The chap did say that he wasn't sure if they still made them before finding some... So I purchased twice as many as I needed just in case...
Lucky for me he had a ruler there and got all the important measurements, I've used the photo for the rest so it's not slowing things down.
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The Bushings are mounted in place, all I now need to do is work out how I am going to orientate the servos.
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I've just finished all the inside servo mounts and linkages which I'm quite happy about, I should be able to print the servo rod profile on to a piece of paper and bend them pretty precisely.
Once I've done the outside linkages, I'll move on to the deck and fixing points for all the other stuff which will need to be mounted inside.
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Harrison... I have watched in awe for many months with your CAD-CAM drawing skills :-))
However I do not understand how you plan to achieve the many linkage alignments that have been shown in perfect symmetry & defined lengths without provision for adjustment in each connecting rod in their respective longitudinal plane ........
It is the pitch of the threadform & the non consistant starting point of the thread that creates this issue.......Derek
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Hi Derek,
All the rods are threaded, I've not shown this to reduce the demand on the PC. There needs to be very little requirement for adjustment as the accuracy of the cut parts will be less then 0.1mm.
I am able to move parts around which are mated to others, I've not been able to show this in pictures but when one part is moved the parts mated also behave exactly as they would in real life. This is called physical dynamics, I can also simulate gravity and perform fluid simulations which may be useful later when I start to model the hull.
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I've just finished all the outer linkages, there really isn't much space between the hull mounting and the control points to play around with. Definitely not enough space to have to ball socketsback to back, which is a bit disappointing.
I'm hoping that there will be enough adjustment on the inner threaded robs to take up and free movement outside, this isn't really an issue on the bucket control as I will only be using forwards and reverse in farmost position and then using the drive to vary thrust as required for meanovering.
The linkages my need to be revised if they are unable to handle the force of the water from the drives, I expect that some real world testing will be in order.
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I think the linkages will be fine, but I'm more worried about whether you'll get the range of movement on the bucket you need.
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I think you may be right about the movement, perhaps a larger servo horn is required for bucket control.
Steering movement seems to be perfect so there should be maximum torque available.
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It may even be the case that there isn't enough bucket movement due to the length of the Robart bushing....
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Thanks Harrison......my apologies :embarrassed: ......I did not explain my question clearly
1. if I could assume you are using typical DUBRO type components
2. if I could assume the chosen size for thread form is 2-56 UN.....
Then we look further.......2-56 UN thread form is 0.072"diameter x 0.0125"pitch
3. accordingly to have two 2-56 thread forms cut into two individual component rods could @ a worst case = 0.025"...or 25 thou per linkage joint out of symmetry
Would this lead you to have six individual servo functions each with the potential of 0.025" imbalance & resultant chatter?....Derek >:-o
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I think you've missed out the servo gear movement :}
I'm not sending it to Mars, I expect the MG995's to have more than enough power to keep sufficient tension on the linkages to ensure the only noticeable movement or chatter will be within the servo gearing.
As long as all the main hardware components are in place, I am sure that there will be room for any refinements that may be required after testing.
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Harrison......I am not really qualified to offer further comment {:-{, however our member FLJ.....may take the challenge & offer a professional comment based upon the fundamentals of accuracy in multiple mechanics when coupled/linked directly to electronics........Derek :-))
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I'm not entirely sure what you mean by "coupled/linked directly to electronics", there will be a limitation on the resolution of the ADC within the microcontroller inside the servo reading the feedback potentiometer. This will restrict the number of points or degrees of movement.
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It may be a good idea to present any suggestions in a way which can be clearly understood by all potential veiwers of this build, so as not to loose thier interest.
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Here are a couple of pictures of the boat as it currently looks (without the Mini MK111).
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I've had to add a couple millimeters to the height of the aft most bulkhead as there is only just enough space between the hull and the deck for the control servos.
To keep the flat deck profile, I have had to add decreasing heights to each bulkhead leading up to the bow.. A very time consuming process due to the method in which the bulkhead profiles have been created (from cuts in the solid hull), it was also very boring.
I spent a good part of yesterday trying to figure out exactly how to fix the superstructure to the hull bulkheads and deck, it needs to be strong but I would really like to get the hull fabricated and start some testing.
Something else which sprung to mind, was having some 'D' link type holes sticking up from the deck at four points so that carry handles can be attached with clips, this will also be very good for storing the boat up out of the way and strapping it down to the bike trailer which I intend to get for it.
I expect that I could add them to two of the bulkheads before and after the main superstructure and they would protrude form the deck, this then brough me on to the idea of having similar type fixings for the superstructure. I could put a good watertight connector on the deck undernear where the structure would sit and it could connect to the bus which (if you've been following the build) is a common control bus providing power and control to all systems with an unlimited potential for expension (well, 65,335 possible addresses).
I'm still unsure exactly how the deck will be secured, as it is 1800mm long it will need to be split up in to sections. This is not ideal, as sealent will be required at each join. Access panels are also something to consider, I was thinking that I should use the same type of system that seals the deck.
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I think that ten fixing points should be sufficient for the superstructure, as the line where the hull meets superstructure is perfect I would like to avoid anything other than a finished an painted mate. This will of course mean that it will not be removable at a later date, but as this is also the case for the hull and bulkheads I don't see too much of an issue.
I'm going to put some additional holes under the main carry holes so as to sandwich the bulkhead between two stainless 'D' plates which I will have cut, this will then take all the ware from the carry hooks.
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I've decided to go with the same aluminium servo brackets from active robots with plastic snap rivets, I think that with the nut and bolt situation there could be some corrosion with salt water and they could work loose. Snap rivets on the other hand always apply pressure to the fixtures and will not introduce any galvanic corrosion issues.
I'm going to have the whole hull anodised once the skin has been welded to the bulkheads, as I expect a good long life out of this boat considering the amount of time that's going in to it.
The deck will almost definitely be sealed with clear silicon sealant where it meets the hull and superstructure, with 'hand' access to each set of bulkhead snap rivets the deck should be easy to remove once the sealant has been peeled off (if a refit is required). The snap rivets to deck will be recessed from the top to conceal the heads and some sealant used to fill these, the servo brackets will then remain a part of the deck section when it is removed.
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Each deck section is going to join at the bulkhead, this is good as it means there is less chance of water leaking in to the boat as the sealed joins will be very ridged. Also it reduces the amount of fixings required for the brackets.
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More boring repetition... %%
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Another picture of some progression in the repetitive bracket placement
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Blimey, I'm glad that's over...
Now it's on to the deck sections.
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I've found an unopened pack of 3mm black polyethylene which is exactly what I would be using for the deck, there is 2.5sq metres so more than enough for the deck and possibly the superstructure. On the full size boat, the hull is made of aluminium and superstructure from composite materials so this is probably the best option as polyethylene is very easy to mill.
As you can see, I have modelled the aft most deck section which only took a few minutes. I'll need to consider access on all the other sections.
Currently she weighs in at 6.77kg, that will of course drastically change with the deck and hull skin.
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Access to the drive servo bay is a little restricted, there is very little room for the lower seal part which needs to be in two parts 'back to back' as it has a seal channel on the top and hexagonal nut recesses underneath for the stainless securing nut/bolt jobbys. If I've lost you then look back to how I have sealed the gun section to the hull, I plan on using the same system for access panels on the deck.
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Harrison.......I note that this posting will be >>>>> over two hundred in number, however the vast % are posts by you
I also see that the imaging software you offer does not afford you with the critical "diminshing" point of view as displayed in Deck1. jpg
Parallism is fine in plan & elevation or a singular plane ....but certainly is not acceptable in 3D...
Please correct me if I am missing something here.............Derek
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Hi Derek,
I would hope that almost all the posts are by myself as this is a build thread which should document progress of the build and not facilitate chit chat between members, that would be for another area as I am sure you would agree..
Are you suggesting there is an issue with the package or my presentation of the image?
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Harrison.....interestingly your latest image Deck2. jpg from this evening does display ...the critical "diminshing" point of view :-))
Just review your earlier image Deck1. jpg & I am sure you see/understand the basis of my comment ......Derek O0
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The aft deck section has been modified between the two images which may have caused confusion.
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Harrison....the moderators here @ Mayhem OK....
Just review your earlier image Deck1. jpg & if you agree that the image is not correct....... O0 .... ask & I am sure the image can be removed....Derek
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Hi Derek,
I'm not sure what you mean about correct? I had made a change to the design of the aft deck section between postings, it is just a progression of the development so I don't want to delete it... As I build this boat I will find things that don't fit together because other things are in the way or, I may have overlooked something which I later notice... It's all part of the build and should be included.
I good example of this is the initial hull design based on the basic drawings... I abandoned this design when I was given the bulkhead profiles by Akers Finnyard, I have kept the posts from this early design as it was part of the build.
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Ok, so Deck2 (second from where I started) seal and fixing plate is done, there are some hex drops in the underside of the sticky-out holes.. as I will be using a 2mm end mill the smallest radius I can mill is 1mm, this will mean that the nuts will press and stay in place as the radius of an M3 nut hex is quite a bit less than 1mm. This method has worked very well with the gun deck fixings so I see no reason why it won't work here.
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ncidentally, I am not looking forward to the water jet cutting quote.... Those longerons are 1800mm long and 5mm thick.
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The cutters have stock of 5mm aluminium so the longerons are taken care of, they've said that 2.5mm (for the bulkheads), is pretty cheap so no real issues there.
Deck section 2 all done and on to the next.
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I think Derek's complaining about a lack of perspective. The images (to me) look isometric.
Both are valid ways of demo-ing a 3d view, Derek.
Personally I'm enjoying the design side of this build. ...Though I look forward to seeing it become a real thing.
Andy
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The view is indeed isometric, this view makes mating easier.
I'm looking to get the bulkheads and longerons cut in the week after next and welded in place, at some point between now and then I'll make some kind of an attempt to obtain the skin outlines from creating surfaces... Not my strong point I can say.
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The keen eye will notice that the deck is not sitting on the aftmost bulkhead, this is because the servo brackets are at 90 degrees and the deck is at an angle running down the boat.
The brackets will bend to accommodate this angle but I'm not going to spend time creating a new set of servo brackets for each bulkhead section, instead I'm leaving it flat for the design until the deck is built and then I'll rotate all the deck sections virtually so that they are all collinear ready for the superstructure design.
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I have no idea what the hell you're talking about but I follow this thread eagerly with every post.
Like the others I can't wait to see this puppy float, zoom and blast things out of the water!
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As per the other comments, i am also watching this thread with interest. Having used Cad to design/draw various projects i also have left the fettling to the real life build. there is always something that does not come to light until bits get fitted in reality. carry on the good work. and please post piccies of the real model. cant wait
regards
colin
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It's really nice to see it has some dedicated followers, thanks.
I'll post pictures of every single part when it's made and going together, I've not done any TIG welding before so that will be fun.. I'll get a bit of practice in on some scrap bits before hand but I am expecting some float tests in the next few weeks.. Fingers crossed.
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Gents...please..... >:-o I was not complaining...just a simple observation & I still contend that the .jpg snaps of deck1 & deck2 are of differing "as displayed" orientation
I too look forward to each new batch of images :-)) .......but I think I said that a few weeks ago O0 ........Derek
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Ok, just to clear this up. All images are 'Print Screen' snaps converted to jpg's in paint, I have at no point changed from an Isometric view so any perceived difference must be an optical illusion.
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There is a good 90mm tall hole on this hatch, as all the other bulkheads are equally spaced it should give good access to all the electronicals.
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I have built and run a kehrer Pibber. " water jets, goes like stink. Thought i would pass on a problem i have with jet drives/Reversing.
First of, if the motors are run in reverse, nought happens.
To get it to go in reverse a "damn" is pulled up, blocking the outlet, and forcing water out through a "hole" in the bottom of the drive unit, torwards the bow. hence reverse. There in lies an exciting problem. if you chuck it in to reverse when the boat has any kind of forward momentum, the bow "dives". Now while this can be fun to watch, it doesnt do the boat any favours. She takes on water.
I have just bought a new transmitter that is programable and i am going to look into mixing motors and the reversing servos so that if the reverse is used the motors are cut.
The other thing i am going to look into is when i bought the kit i ordered reversing buckets. Now for some reason known only to my younger self i never fitted these. Just used the "damns" that came with the jet units.
wether these will make any difference i dont know. I will try them out, Very CAUTIOUSLY. can get expensive otherwise.
love yer Cad skills, wish i couls afford inventor. just use Turbo Cad. not quite so easy to use.
Colin
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Thanks for the advice. :-))
The motors are only running forwards with the buckets for reverse, there will be an accelerometer on board which will take care for ensuring that the boat behaves in a realistic manner. If I through it in reverse it should slow down in a scale fashion, or at least that is the plan.. I expect that there will be an override function but the software will be written so all power is smooth in comming in, I'm not using a standard remote so the sky's the limit on servo control.
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oh gawd, more geeky info please!LOL. and i,m strugling with my bog standard Futaba kit. and i mean strugling. did buy a servo slower downer today for the buckets.
just fitted one of them, buckets that is, shaped quite differently to the "damns" fitted previosly. will look back through youre thread to see if they bear any resemblance to my new ones.
colin
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A bit more progress made today, I've decided to do all the Deck parts then seals then covers in an attempt to make it less boring.
Once you've done three it starts to get a little dull!
I'm going to add a few mounting holes in the bulkheads for things like speed controllers, electronics etc.. as I want to get them cut out while I am away for a couple weeks, this gives me all next week to try and make sure I have everything covered that may possibly go below deck...
I was thinking of storing the depth charges below on a sloping storage type affair with some kind of chain lift which will bring it up at an angle, switching it on with a magnet/reed switch then set the depth/time with infra red just before dumping it overboard. Obviously a lot more could be stored below deck so I'm thinking it may be a good idea, the aluminium servo brackets are favourite so as long as there are plenty of holes on each bulkhead It's pretty well futureproofed.
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I've been giving some serious though to the couplings and although they seem great, the Huco ones just aren't going to handle the power at the RPM I will be reaching.
I am thinking that perhaps, I need to go for a solid stainless coupling with set screws and make sure that the motor mounts can adjust to hold the motor perfectly aligned.
My local engineering company can produce these for me for less than the cost of the Huco couplings and I am sure that they will be better balanced as they will have a much smaller outer diameter and have better symmetry, I will put the set screw on opposite sides at each end so that any imbalance will be a gyration and not a wobble.
The pressure is on for me to get the hull part finished before I go away, rather come back to cut bulkheads than wait for 2 weeks..
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Have a look at NoMustangMark's couplings, they have two metal part to them like the huco but have a silicon tube in the middle. I've not used one but think it's a very good idea.
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Hi Phil,
Thanks for that, I'll see if it is viable.
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Harrison says..... "so that any imbalance will be a gyration and not a wobble" ...you could consider two M3 grade 304 stainless steel hollow pointed grub screws @ 180 degrees to each other in each coupling half but do not phase the coupling halves %% ......Derek
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I had thought about that but the set screw meeting the flat face of the shafts will be closer to the center of rotation. I may be worrying about nothing of course.
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if you have problems with couplings try kehrer. designed for high revs.
colin
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As you can probably guess from my lack of postings, I've not had time to do much to the boat before going away. I'm pretty close to finishing the deck now, It's taken a little longer than planned but unfortunately other things have taken priority.
I've been practicing with the welder, I've been trying to weld two very small pieces of stainless steel together which is very difficult indeed. When I come to weld the bulkheads to the longerons I should be an expert!
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I'm hoping to get all the deck sections completed in the next two days, so I should then be able to move on to the fixing points for the electronics and weapon systems.
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Just the hatches to do now and the deck is finished.
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Missing you, or rather your updates. Any news?
colin
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Hi Colin,
I'm missing posting..
I've been super busy with things lately, I've been taking the resi-mate pad to shows and designing more hobby products. I'm at the Bmfa nationals at the weekend so quite a lot to do for that up to then and during..
I will be taking may laptop with me though so expect to get much done then and after.
I plan on bringing some of my ideas to modellers by making them easily manufacturable, a couple of which initially being for aircraft.
I would expect an update on the Hamina early next week.
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ohhh god..superb work...its indeed...excellent...
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If you ever sell plans, and parts, for building that gun and/or radar - I'll be buying one for sure. My next project will probably feature a gun much like this, and it would be superb to have a fully functional gun!
Looking forward to more news on your spectacular build.
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Hi Harrison,
How's it going?
Martin :-)
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Hey Harrison, any new progress?