Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Navy - Military - Battleships: => Topic started by: Tug-Kenny RIP on May 22, 2012, 12:25:00 pm
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This is my first attempt at building a model boat from the Military fleet.
I decided on Fairmile D from the second World War as I saw a great model recently at the local Fair and was impressed by her on the water. High manoeuvrability and speed was the order of the day.
The detailed information on scratch building is very scarce and it took a lot of research to come up with details and plans. I've bought a few books and cobbled together some pictures which is enough to get me started, so off we go. I hope to get further help as we progress.
First off was to decide on a scale. I first chose the scale of 1:32 and show the frames construction and assembly below. It soon became apparent that this was on the small side when it came to fitting motors and electrics so this was abandoned in favour of a scale of 1:24.
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Here's the pictures of the frames connected to the rib which gives it it's size.
I've now left this version on the shelf and got on with the second version
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The frames drawings were re-scaled and printed out. These were laid onto 4mm marine ply and cut out.
As the deck curves up towards the bow it was decided to fit a block to the bow post to raise the assembly as we worked towards to the bow.
PS
You can see the smaller version on the shelf behind the bench.
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To glue and fix them into position we used a few clamps and blocks of wood.
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Here's a few shots of the planking going on. To make these involved a lot of wood cutting on the bandsaw, which filled the workshop with dust.
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I've taken Bluebirds advice and gone for diagonal planking on the stern section.
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The Bow section has a gorgeous curve which needed the planks bent as well, so here is my attempt.
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I then fitted runners along the side to accentuate the curves and allow torpedoes to be launched when I cut out the slots. %)
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The next job is the filling and sanding down of the hull. I see the weather has improved so I shall tackle this outside in the fresh air.
to be continued .........
ken
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We are trying a new tack with the filling this time and using Peter Fitness's idea of using Polyfilla. I had a small tube from decorating days and tried it on the bow.
This seemed to work OK so I went to town and got some exterior Polyfilla. It wasn't until I started pasting it on that I saw it contained Cement. :o Here's the pictures so judge for yourselves. I'll see if it sands down tomorrow when it's gorn orf and see what it comes out like.
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We sanded off the cement overcoat with power tools. (took a few sheets of sandpaper !) and snapped on the indoor Polyfilla.
Must say it's lovely stuff to work with. Sands down beautifully, and so smooth. I put it in the sun to dry off before spraying and found the wood contracted with the heat of the sun. It was 28 degrees out there. Cracks have started appearing between the Butt joins and the wood strip cladding had rippled a bit. It could be due to the wood glue that I've used with the glue gun. I've now re- covered with Polyfilla again and will sand down tomorrow.
I'm now thinking that Epoxy is the way to go, either inside or outside is the question. I'll let you know how I get get on. %)
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Looking good, Ken :-)), keep the photos coming.
Peter.
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Hi Ken
I'll tag along with your new build.
Re filler - non modelling use so far - Ive just used some fairly cheapish Wilkinsons wood filler. It looks, works and hardens exactly like polyfilla and sands lovely.
Dave
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Hullo Ken.....that round wooden outdoor table is really getting a nice hue of assorted colors {-)
Seriously tho O0 .....I think an external coat of epoxy & tissue will protect the pollyfilla....Derek :-))
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Looks good kenny :-))
Have you decided what weapons it is getting?
And what colour scheme?
Colin
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Hi Ken, watching this build with great interest as the Fairmile is going to be my next project. I have never
used polyfiller on any planked hulls I have always used car body filler, then car epoxy & close weave mat.
Then 2 coats of resin then rub down.
john
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Have you decided what weapons it is getting?
Maybe - maybe not - but I bet he has already figured its bollard pull O0 {-)
Dave
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It's gonna have Four motors and should 'shift' her around the lake :}
I've been working continuously since the last report. Now got the 'scallops' in. These are the torpedo launch ramps each side. The hull has recovered and been sprayed in primer and I will be using epoxy on the insides to keep the damp stuff out.
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Hi Ken, watching this build with great interest as the Fairmile is going to be my next project. I have never
used polyfiller on any planked hulls I have always used car body filler, then car epoxy & close weave mat.
Then 2 coats of resin then rub down.
john
Hi John,
I'm bringing my 1:32 frame to Wicksteed to sell if you're interested. You might have smaller hands than me. {-)
ken
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Hi John,
I'm bringing my 1:32 frame to Wicksteed to sell if you're interested. You might have smaller hands than me. {-)
ken
Hi Ken I have a spare fiberglass 31.5" hull I was thinking of converting.
Thanks for the offer mate, indecently my hands/fingers are like a hand of bananas even my guitar has to be a classical type with the widest neck I can find. {-) {-)
john
:} ken
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Looking good, trial and error, that's how we learn. As for the issue of the scales, my wife tells me that size isn't every thing!
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..... and we say their bottoms don't look big in that dress. %)
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..... and we say their bottoms don't look big in that dress. %)
I did once still got the scars !
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..... and we say their bottoms don't look big in that dress. %)
my wife bent over to pick something up of the floor, I said crikey the last time I saw something that size they
were throwing a saddle over it, >>:-(
I never saw the punch comming {-)
john
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I've started work on the upper deck stuff and have attempted the Cabin and Bridge.
Not easy I can say. The shape is a complex angled wall system and it's taken days to get this far.
See what you think.
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Looking good Ken.
Dont moan about the angles, my last one was all angles, near drove me barmy, but funny enough I actually enjoyed doing it.
Just take your time and cut out cornflake packet cardboard templates first, it saves on plastic.
Keep it up.
(http://i124.photobucket.com/albums/p8/DickyD_photos/Smileys/avatar49659_2.gif)
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you are doing an excellent job Ken.
john
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Just take your time and cut out cornflake packet cardboard templates first, it saves on plastic.
Thank you Dicky, what a great idea. How did you know I ruined so much plastic. <:(
I have never thought so hard as this one. It's going very slowly, but we're getting there.
I do have a problem with the open deck aperture, however. That cabin block is the only large hole I can make in the deck for getting at the insides. I have been thinking about a larger base plate to fit in a recess, but I might get water ingress problems. Has anyone ever thought of a complete deck removal system to join around the top of the hull ?? That way, complete access to everything below decks would be possible. ?
Built the machine gun emplacements today but not much to show for it at the moment. Have to leave it now as I'm preparing for Wicksteed weekend and working out what will fit in the car. OOOOH!!! it's exciting.
ken
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I have same problem with access on several of my boats Ken.
What I do is to make a hatch cover level with the deck over the bits I might want to get to on an irregular basis [servos, rudders, motors etc]
I run a thin bead of bathroom silicone around the hatch cover and weight it down till the silicone dries. I do not use too much silicone but just enough.
If I need to remove hatches then a thin blade under the edge of the hatch will split the silicone with very little trouble.
Old silicone will rub off easily and can be replaced as before.
Hope this helps Ken.
(http://i124.photobucket.com/albums/p8/DickyD_photos/Armidale/DSCF0052.jpg)
(http://i124.photobucket.com/albums/p8/DickyD_photos/Armidale/DSCF0178.jpg)
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I made a similar hatches on my Armidale and my Sentinel, but instead of using silicone I used a thin smear of petroleum jelly (Vaseline). This seals the hatch, but allows it to be removed very easily. Provided the deck paint is sealed with a clear finish any excess petroleum jelly wipes off cleanly. To date, no water has entered either hull via the hatches.
Peter.
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Hi Ken
Go to mayhem section painting,finishing and care.
Click on subject Fairmile Dark Scheme.I have enclosed a photo of my hatch details.
Hatch line is hidden by rear torpedo tubes.
Gra
http://www.modelboatmayhem.co.uk/forum/index.php?topic=25052.msg302479#msg302479
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Once again, 'Mayhem comes to the rescue'.
Thank you for all your ideas. It's the way to go. When I build the deck I will sink in these recesses for a flush fit.
I do like your build blog, Gra. A lot of useful angles shown, as my plans are two dimension it gets difficult to work out the 3D view, but we're getting there. Looking forward to building the Oerlikon mounting. %)
ken
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Still working on the 'finish' of the Hull and applied yet more paint. As it's looking more like a boat nowadays my thoughts are turning to the motor system.
Can anyone recommend what type of motors I should fit please. Four will be needed to fit width wise and these will have to be lined up with the four prop tubes before cutting the hull can proceed.
I'm hoping that this boat will be the fastest yet so we are looking at getting up on the plane.
cheers
ken
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I have been working on the hull finish for ages. Just cannot seem to get the planking flush and seam free. I've lost count of the number of coats of paint there is on her now.
Every time I look at the hull it seems to have grown more blemishes every night. %)
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Today I got out the power tools and ground the whole lot off again. The surface is now nice and flat once again.
I have been debating what to cover it with and have decided to go the fibreglass route.
Any tips please ?
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PM SENT
Dave
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Replied
and autograph sent. {-)
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Well, I've had a chat with my paint advisor and purchased new 'stuff'
It's a filler made by U-Pol and it's lighter than P38. Plastered it on yesterday and spent today sanding it down. The hull was then sprayed with filler primer and here's the result.
Must say I'm quite pleased with how it's going and have a few 'dings' to refill to complete it, but on the whole it's coming along great.
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Good nice one Ken you can fil those slight imperfection with the new filler and they will simply dissapear and you will have a very nice smooth hull
Dave
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Certainly will. I'm very pleased with this filler and I want to produce a flawless hull for a change. 8)
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Ken I keep telling everyone about it and everyone says HUH it is far to expensive, Nothing is to expensive if it saves you time and effort to do a proper job
Dave
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I agree with you, and using this premise, I also bought the Filler/Primer in a great big tin.
I did find I was using up all my sandpaper as it was clogging when used dry ! but it's all done now.
Cheers, me ol paint splasher. :-))
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What You could allways do is to buy D/A discs in 80/180/500 YES I know htey are expensive BUT weigh up hte costs involved they would last for years and they dont clog as easy as wet/dry
http://www.ebay.co.uk/itm/Discs-6-DA-Discs-Velcro-Mirka-SANDY-180-Grit-box-100-/270775662618?pt=UK_Body_Shop_Supplies_Paint&hash=item3f0b7cb81a
Just put DA discs into a ebay search if you do decide to get some then go for the velcro type as they dont clog as easy
Dave
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Those things are absolutely brilliant, reminds me I need some more myself 8)
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I had a look and they look just the job for my workshop. I shall have to get the gun as well.
Cheers for your help.
ken
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I had a look and they look just the job for my workshop. I shall have to get the gun as well.
Cheers for your help.
ken
Kenny what do you mean get the gun idea for my workshop
Dave
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Isn't that what they call the sanding disk holder. I've been looking and they appear to be Air driven. I do have a compressor but it's a bit noisy. %)
I'm going to the shops to search out these devices as I notice they have a 2 inch disk model.
Thanks for your help so far. I've just filled some of the holes and now waiting for it to dry.
ken
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I hope thats a typo? otherwise I'm sure its not something one wants to discuss in an open forum lol ;D
Thanks for pointing that Essex. I've managed to correct my spelling in time. {-) {-) {-)
ken
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I have reread and then imagined the said typo %) - {-) {-) {-)
Dave
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It's probably better to imagine it. ;)
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Hi Kenny... the hull looks great. What was the name of the U-Pol filler, it sounds interesting?
Lee
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TOP Stop is readily available in Halfords or Even use Easy Light horses for courses.Search Top Stop on ebay as well.
TBH it doesnt matter wich one you use BOTH are as good as each other.
I use either or in the workshop on a Daily basis and simply wont use anything else,it is flexible and SO SO easy to sand.Others will reccomend Isopon P38 BUT I will Guarantee you one thing they havn't tried this stuff.I do filler work and paint ,on a daily basis so the last thing I need is filler that takes time to rub down ,I need something that will ease the hard work and Guys and Dolls this is the stuff to use Believe you Me I do know what I am talking about.This stuff is ready to sand in 10 mins and if you leave it for 12mnths it will not be rock hard and unsandable.
Dave
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Today I filled in the 'dings' with some more U-Pol and sanded flat. I've used the rest of yellow filler/Primer to re-cover the marks and this is the final job.
Grey undercoat soon. Can't stop smiling.
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See super STAV to the rescue AGAIN,me thinks I will just have to CHARGE for consultations {-) {-) {-) {-) {-) {-) {-) {-) {-) {-) {-) {-) {-)
Dave
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.
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It's probably better to imagine it. ;)
Makes it hard for us with no imagination O0 O0 ;D ;D
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Better that way, believe me. 8)
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Started fitting the MMB's prop tubes today and need to think of buying props.
Can anyone tell me the number of blades I should get for some 35 mm propellers please. Cornwall boats have 3 bladed ones in stock but are out of stock on the 4 bladed ones (which I somehow prefer !)
Cheers folks.
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What motors and voltage will you be running Ken?
Bob
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Hiya Bob,
Haven't decided on the motors yet. My main problem seems to be the shallowness of the hull.
When the tubes are finally fixed into place there will not be the high enough angle for my 900's. I have been studying the sizes available in the 12 volt range and cannot decide yet. I've worked out that the 35mm props govern the angle back into the boat if laid correctly. I'm even thinking of dropping the angle away from the hull bottom, but this would put them below the keel line.
I am working from wartime pictures which leaves a lot to the imagination. I want a boat that will fly. %). I was considering brushless but discounted the Lipo idea, so back to the drawing board.
ken
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Longer shafts My boy
Dave
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Hi Stav,
They are specially made and are 13 inches long. The motors are already way ahead of normal, and two are beyond the middle of the boat. I'm thinking I should have gone the 'belt drive from above' approach.
I will post some pictures before I go any further, as the slots in my nice new hull are rather longer than I would have liked. :((
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nothing stopping you mounting the 900's upside down so to speak,dont it in the past and it works
Dave
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mmm!!!! I'll check it out.
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How many 900 motors are you thinking of using?
Bob
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I only have two at the moment and was thinking of driving two props each. (somehow) Failing that, then perhaps 4 smaller types of motor.
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Kenny that is quite simple.
Cut the tubes so they are all in line inside the hull.
As the shafts leave the outer shaft fit Toothed Belt Gears to each shaft.
Fit out the outer shaft as normal si it is always direct drive and take the belt to the other shaft.
With this way any problem with the belt you still have 1 driven shaft on each side to get her home.
Bob
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hey that man. What a thinker. Smashing idea. I'll line it up tomorrow and try it. :-))
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Don't bother using 900's if you're only using 35mm props, waste of a good motor better used elsewhere... 8)
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Four bladed and four of them ? maybe 24 volts. %%
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Kenny that is quite simple.
Cut the tubes so they are all in line inside the hull.
As the shafts leave the outer shaft fit Toothed Belt Gears to each shaft.
Fit out the outer shaft as normal si it is always direct drive and take the belt to the other shaft.
With this way any problem with the belt you still have 1 driven shaft on each side to get her home.
Bob
Neat idea, O0 O0 :-)) :-))
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I've taken a few pictures to show the line up of the tubes.
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I placed the 900 motors in to get the line up, but they do look rather large. You may be right Andy. %)
Note. They wouldn't be 'side by slde', but spaced apart. They only show this way because the magnets clamped them together.
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G/day Ken,
My info indicates these boats would have been lucky to do 30 knots in real life why do you need such large motors.
My boat has two Graupner speed 600 and two 545 motors with a 8.4 v nimh battery powering each pair of motors and its quite fast enough when required.
I will get a photo of a side on view of my prop shafts for you should have done it when i did the other photos for you.
Hope this will help with your build.
Gra
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Hi Gra,
Thank you for that. I've rooted through my 'stores' and come up with some 500's which I've just placed in for the photo.
I must say it does look the part as the shape is just right. I shall be pricing up a set of 12 volt 600's now.
Here's a picture of the angle I have to use for the prop tubes. They do hang lower than the keel but there is no way around this. It should be OK in the water with enough thrust for 30 MPH. (not scaled down :})
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That does look better Ken.
Bob
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Funny ol Hobby with it's ups and downs. That's why I ask the collective on here as two heads are better than one.
ken
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Kenny,
With 35mm props you will need 10,000+ revs to give decent performance on this heavy model.
It should be heavy when ballasted down to her marks and these are not a fully planing hull so not too much bow lift.
Bob
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Good Day Kenny
I've been watching this build with interest, as I'm getting the bits together to build a "D" boat, unlike you I don't have the patience to build from scratch, I bought my hull from Kingston Mouldings, Robin from kingston suggested putting 4 x Graupner Speed 500E in to get it a scale speed.
Have a look at the performance on the video's on his website.
http://www.kingstonmouldings.com/pdfairmiled.htm
Below are the drawings from the shaft arrangements.
(http://s19.postimage.org/9k45n7plr/image.jpg) (http://postimage.org/image/9k45n7plr/)
(http://s19.postimage.org/bq31vgifz/image.jpg) (http://postimage.org/image/bq31vgifz/)
Richard
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G/day Ken
Couple of photos as promised.
(http://s12.postimage.org/eqokolu61/DSCF1550.jpg) (http://postimage.org/image/eqokolu61/)
(http://s11.postimage.org/sf8918hkf/DSCF1555.jpg) (http://postimage.org/image/sf8918hkf/)
(http://s18.postimage.org/5jd7ceho5/DSCF1552.jpg) (http://postimage.org/image/5jd7ceho5/)
Gra
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G/day Richard
If you look on page 3 you will see a Kingston hull build started by Frank M.
gRA
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Good Day gRA
Thanks , been watching that one too.
Richard
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G/day Richard
If you look on page 3 you will see a Kingston hull build started by Frank M.
gRA
Hi Gra,
Where is this please. The Kingston site doesn't play for me as the files are shielded from me by my security system.
Thank you for the pictures. I shall be using your guide to proceed with mine.
Hi Richard,
Thank you for the drawings. Just confirms the tight fit under the hull. By using the recommended 35mm props mine will be below the keel line due to my rubbish build of the hull. Not to worry though, as long as it sails.
The motors are proving a challenge as I want to use 12 volts. I have two 600 motors at this voltage but the other two 600's are marked 8.4 volts. They run faster on 6 volts than the others on 12 volts ???
I am considering running them in series from 12 volts. I have been looking at the shops trying to find the 12 volt versions but drawn a blank. Any suppliers out there. ?
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Ken
Go to page 3 of this section build started by Frank M.
You will find two entries started by Frank on page 3.
Gra
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Page 3 of what ? Are you referring to the Kingston site ?
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Ken
Page 3 of this column Warships Navy Military.
Gra
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Its probably a bit late now but would some low KV brushless outrunners do the job?
Something like 4 of these?
http://www.hobbyking.com/hobbyking/store/__16229__NTM_Prop_Drive_Series_28_30A_750kv_140w.html
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Thank you Gra.
Here's the reference. http://www.modelboatmayhem.co.uk/forum/index.php?topic=31895.0
This is a rather excellent build and it encouraged me to proceed.
Is Frank M still on the forum ??
Thanks for the heads up Essex, but I've never done 'brushless' so I'll go the way of Brushed 600's for now. I've got 2 and looking for the other 2 @ 12 volt.
I've been all day fitting the external Propshaft supports and trying the line, to get it perfect. No glueing yet as I'm tampering with the motor end and lining it all up. Great fun. Lots of sawdust and gaffer tape but it's looking the part now. O0
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Here's the pictures showing ready to glue in. Because the hull is almost straight at the base you will notice the larger than usual slots for the prop tube entry. I will fill these, when the time comes with fibreglass.
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Good morning Ken.....do you have any fear of the center two props cavitating >>:-(& <*< fighting for water? :o ......Derek
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Good Day Kenny
The motors are proving a challenge as I want to use 12 volts. I have two 600 motors at this voltage but the other two 600's are marked 8.4 volts. They run faster on 6 volts than the others on 12 volts ???
I am considering running them in series from 12 volts. I have been looking at the shops trying to find the 12 volt versions but drawn a blank. Any suppliers out there. ?
When you talk about a 12 volt version are you talking about the motors, try Cornwall Model Boats, http://www.cornwallmodelboats.co.uk/acatalog/graupner_3302.html
The video's from Kingston Model Boats are attached below.
http://s1221.photobucket.com/albums/dd468/Rogue-Wolf/?action=view¤t=fairmileDmovie1.mp4
http://s1221.photobucket.com/albums/dd468/Rogue-Wolf/?action=view¤t=fairmileDmovie2.mp4
http://s1221.photobucket.com/albums/dd468/Rogue-Wolf/?action=view¤t=fairmileDmovie3.mp4
Do you have a copy of Anatomy of the Ship - The Fairmile D Motor Torpedo Boat, I've found it very useful.
Richard
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Good morning Ken.....do you have any fear of the center two props cavitating & Oh Yeah fighting for water? ......Derek
Hi Derek.
Hopefully not, as this how the real one looks. I assume they are fed with extra water from the two in front.
It does bring me to my next question however. Which way do they turn, in or outwards ?
cheers
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Thank you for the information, Thunderchild. I enjoyed the films. :-))
Also thanks for the heads up on Cornwall boats for the motors. Funny, I looked but I didn't see them in the list ?? :-)) I started ordering the props and when one wasn't in stock it killed my order. Evidently they don't take orders in advance. I shall try again soon.
Cheers
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Still a problem getting hold of the Props, but I am proceeding by securing down the tubes.
First I taped over these gert big holes and filled the inside section with epoxy. Today I removed the tape and filled over the tubes on the outside with P38 and will shape them when it's dry.
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OH KEN go into the corner AGAIN, and write down 10 million times I should NOT have used P38 as it is so so difficult to rub down and STAV told me so
Dave
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I did think long and hard on this one Stav and decided on P38 for it's toughness.
You know how I drive. %)
I have the power tools to grind it down smooth so I will let you know how I get on. The epoxy had dribbled through to this side, as expected, but it didn't like sanding at all. It went all so rubbery that I could trim it with a knife. This led me to my decision to cover it from the outside with something sturdier.
Thank you for mentioning it. Keep em coming. :-))
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Good Day Kenny
If you're in a hurry for your props, try Float a Boat in Australia, Raboesch props 35mm, 3 blade, 'D' Type 35.9mm Pitch, approx (Au)$20.50. www.floataboat.com.au
Richard
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Thank you for that , Richard. It was just last night I placed my order for 35mm brass props along with some 600 motors and two rudders. (£90) :o
I was going to scratch build the rudders but decided to get a move on and save time. I shall be shaping them as per the drawings so they should be Ok.
Today I sanded down the filler on the prop tubes and was called away to go shopping, so I've finished for the day as it was heavy bags and I'm now done for. %)
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Today I fitted the new propellers and lined up the rudders. The rudder blades were a bit too long, so I've trimmed them down since the picture was taken.
I've fitted the steering arms and linked them up to the servo. Notice the aluminium tube over the long shaft to stop flexing. The servo is located that far into the boat as there will be a secured deck above and this will ease maintenance.
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Looking at the enlarged pictures, I see that there is room to fit 40mm props should I require any 'grunt'. I'll see how the 35's get on first of all. %)
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The motors have been finally fitted. What a job, lining them all up correctly with no friction or bends in the pipe work.
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The deck has been cut and placed on to show how little room there will be for big hands to mess around inside.
This will not be affixed until more heavy work has been completed inside. You may have noticed the screws holding the rear motors on actually have nuts under their heads. This is just in case I have to remove them when the top is on, as access with a screwdriver is limited..
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I have been working today on wiring up my twin 600's in my Fairmile boat. The 500's will be tried tomorrow.
I wired in an amp meter before testing and was severely surprised with the current consumption. As I was still lining everything up for smoothest running I was able to watch the current loads under different circumstances and have some info which you may find interesting.
Initially one motor took over 16 amps (on the bench, with no water to push around) at full throttle. After re-greasing the prop shafts and getting them true, it dropped down to 11 amps on full speed. (noisy it was as well). At half throttle things seemed much better and it ran at 4-5 amps. If I run two, with 35 mm blades I should imagine I'm not going to get more than half an hour running on a 7 amp hour battery. :o
I shall be testing the 500's separately to see what their results might be. The plan is to switch them over for cheaper slower running. I think the idea of running all Four motors at the same time might be a bit too ambitious for my battery.
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Good Day Kenny
According to the stats, the Grauper 500E are rated at 2A current drain at max. efficiency.
Richard
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The bench testing of the 500's was very pleasing. First of all they only took 4 amps each at full speed driving dry Prop tubes, and secondly the noise was extremely quiet and smooth. The R.P.M is much less than the 600's and also the whistle on the speed controllers is much reduced when compared to driving the 600's.
I have now wired in a 20 amp double pole switch which controls the Esc's output to either pair of motors. I decided not to go with all four motors at once as the current consumption is extraordinarily high. Approaching 25 amps before I reduced speed in fright ......phew !!!!
My 500's are not E's Richard but the results are very similar to your records. Thank you for your input. I do appreciate help, so keep em coming. :-))
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Hi Ken
Your build is coming along nice, it looks good.
May I make a comment on the MTroniks motors which you are using :o As you have found out through bench testing; they are extremely hungry little critters for the amps they draw. But, having said that they are a good performing motor I am not sure if you can recall the very first Wickstead that we all attended you and I met violins now playing....... {-) I brought with me the model MTB488 I ran it once or twice on the Lake. Martin asked if the speed boats could be run later on in the day it wasnt a speedboat but by it can shift.....and inside there are 3 MTRONIK 500s (fan cooled).
The 2 outer motors are switchable on/off. This allows one to manoeuvre with the centre motor and all-out speed in a straight line engaging the 2 outer motors. The way I achieved the switching was to switch the signal wire to the speed controller. The speed controllers are the old Electronize type with the ZN409 chip in them. The one which drives the 2 outboard motors was beefed up by adding an extra output transistor and the switching is done via a servo which is on the channel 5 or 6 (i.e. the undercarriage channels) - the one with the switch on a 6 channel transmitter & receiver :-))
The model is also powered via 2 x 4 amp 6 volt lead/acid batteries.
Sad to say, as you can imagine it only runs for mere minutes flat out. I do have batteries and plans to convert it to NICAD but .......its still in the pipeline, which is getting longer by the weeks {-)
We know we cant tamper with these modern day speed controllers with auto-reset cos if you switch the signal off to these modern controllers half way on throttle opening, it will remember that position as neutral.
Suppose you could use Modern day EEC (switching the signal on/off) if you remember to set your throttle stick at neutral, before you engage your 2nd speed controller to bring in the 2nd pair of motors.
This will bring or should in theory bring everything in line.
KEEP UP THE GOOD BUILDING mate, hope to see you at Wickstead in the future.
I have put some pics on of the MTBs 488 internals and the blurry picture is the microswitch and servo.
Aye
John
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Hiya John, so nice to hear from you. I hope you're feeling better these days. :-)
Regarding the switching, I figured I couldn't change the motor loading during run time as the current would melt some switchers !! This is why I've gone for a large manual switch to be used at the dock side. I shall be trying her out soon on the water by running one test with the 500's and another test with the 600's. Decisions can then be made how to complete the layout for general use. I'm considering changing to all 500's as they are lovely little motors and I could run four at once.
ken
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Hi Ken,
Fairmile is looking good!!!
I remember reading about a Fairmile a few years back and if memory serves the builder passed comment that if he did one again he would leave the rudders slightly oversized as he felt them a bit small / not enough surface. Think that was a kingston mouldings 1/24 scale job
and ruuning gear was george sitek/ radstock
Anyway she's looking good.
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Thank for that. I've re-shaped them so it's all down to the launch to find out.
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It's finally warm enough to get to the water side. Testing proved I could do without four motors, so I've opted for the 600's.
I have torn out the insides and started again by assembling the 600's to the inner props and putting blanking caps on the outer shafts. The wiring has been reduced to a neat set up with two speed controllers.
It was time to continue with the cabin construction. This was then sprayed to see what lumps show up. These were sanded smooth and it was resprayed again.