Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[zooma]

Hi Zooma
Check up on the 3648-1450kv Hobbyking have drop it off their website !!!

I am lucky, I have two spares in my bits box!!!

Canabus

Hello Harry,


I had a pair of the red 3674 2250KV in-runner motors arrive in the post today.


The 120amp "waterproof" speedo that you suggested arrived earlier, so when I get back from my trip to the caravan I will connect one of these motors up to the ESC and make sure it works OK.


I am tempted to try a pair of non water-cooled speed controllers in my Corvette running a pair of 3548 900KV motors.  I have not checked yet, but I guess Surpass make smaller ESC, but I have plenty of room in the Corvette (!) so I could go for safety and fit a pair of these 120amp ESC as I can use them for other things too!


Bob.

[canabus]

Hi Zooma
So the 2250kv's would be 24975 rpm on 3S, that's 3,500 rpm more than the 1450kv's on 4S(unloaded).
The corvette will fly!!!!
No boating this weekend, off to the shack to cleanup!!!

May slip the Waverider in for a quick spin at the end on the block!!!
Depends on weather and tide!!!

Harry

[zooma]

Enjoy your weekend Grandad.


I was thinking about a pair of 3548 900KV in the Corvette - a much more modest power that would be more suitable perhaps (?) - at least to start with!


The 3674 2250KV red car motor I was thinking could be a good choice for the Javelin/Swordsman/Rapier as a replacement for the no-longer available 3648 1450KV that I would have preferred if I was still able to buy one.


I am also away this weekend - I will be celebrating my 71st birthday by staying in our static caravan (close to our club lake!) and taking my Rapier with me.


An Inception and a Pursuit are kept in the caravan as they don't take up much space and are always ready to go if I fancy a "fast blast" - but I only run these "out of hours" when regular club members are not on the water as they a bit boisterous. I ran the Pursuit on 4 cells last Sunday afternoon when nobody else was on the water and it was super-fast and a real challenge to keep it within the designated club water limits!


Stay safe!


Young Bob.

[ChrisF]

Hi Zooma
So the 2250kv's would be 24975 rpm on 3S, that's 3,500 rpm more than the 1450kv's on 4S(unloaded).
The corvette will fly!!!!
No boating this weekend, off to the shack to cleanup!!!

May slip the Waverider in for a quick spin at the end on the block!!!
Depends on weather and tide!!!

Harry - with talk of such high revs have you ever had any problems with the prop shafts? The Raboesch Maintenance Free ball-raced and Delrin bearing type that I use are stated as being rated to 15k and the model down is rated to 10k. I know that shafts for race boats use different bearing materials. I'm ensuring that by battery choice I'm keeping the revs around 11k or less which is fine for my type of boats.


Happy birthday for your upcoming 71st Bob.


Chris

[zooma]

Hi Chris,


Most fast racing boats have flexi- drive shafts these days, but you are unlikely worry your 5mm shafts in your Fairey fleet.


My Rapier is as fast as anything that is not surface piercing and that is trundling around nicely on a plain bearing 5mm prop shaft.


I just stripped the shaft to grease it after checking that I have no wear (end play) and it looks fine - and this was the original shaft (sort of) that must be very old - but I wanted a slightly longer inner shaft so I bought a spare 5mm maxi- shaft stainless inner from modelboatbits.


Strangely, the 5mm maxi shafts are a bigger size 5mm than any of my old 5mm inner shafts so I had to drill the bearings out slightly to be able to fit it !


Enjoy your weekend- and don’t worry about your prop shafts!


Bob.

[ChrisF]

No, not worried Bob, as I will be running well within the designed limit and only able to go fast for short bursts at our club. Just wondering what the situation is when running at the 20k revs plus that Harry was referring to.

Chris

[canabus]

Hi Zooma Bob

Well happy birthday, old chap !!!!

My prop shafts are 4mm stainless with a ball race top bearing and a Teflon lower bearing.
The whole drive line is from Banggood, but, a club member makes the Teflon bearings.

Grease is silicon waterproof.

My test area at the shack has no speed limit, but me go over fast !!!!

Harry

[zooma]

Thanks Harry,


I am pleased to hear that there are no speed limits to reduce the amount of white water you can make with your Waverider when you pop out from your shack to have a sail.


Ball raced prop shafts? I must admit that I have never checked Banggood for prop shafts, but I will take a look when I get home to see what lengths are available.


Having never owned or run a boat with a ball raced shaft, I will see if I can find one to fit my Swordman build so I can give one a try, but I am reluctant to take the M5 shaft out of the Javelin as it will make more work and I have plenty of other projects on the go at the moment!


I am off to the lake now - the sun has just gone in and we have had a shower, so some of the club members will have gone home as they don’t like their boats getting wet (!!!) and this will give me a it more space to run, so I will put the Inception in the boot and give it a run.

[zooma]

Hi Zooma Bob

Well happy birthday, old chap !!!!

My prop shafts are 4mm stainless with a ball race top bearing and a Teflon lower bearing.
The whole drive line is from Banggood, but, a club member makes the Teflon bearings.

Grease is silicon waterproof.

My test area at the shack has no speed limit, but me go over fast !!!!

Harry

I can’t find any ball raced prop shafts on Banggood which is a shame as I would like to try one - and their prices would be good too

[canabus]

Hi Bob


Banggood ID 934428 from 10 to 35cm length.


Also they have nice CNC props.


Harry

[zooma]

Thanks Harry,


When I get back in the week I will take a look!


Enjoy your weekend!


Bob.

[Stuw]

Hi there “zooma”


I’ve only just joined this forum as I’ve stumbled across your posts regarding the Javelin. I have a Javelin that I built in about 1994 with an ic glowplug motor. It’s been in my parent’s attic for years until recently as they were having a clear out. Lockdown has renewed my interest in the boat and I decided last April to look into converting it to electric and giving it some tlc as the paintwork is a little crazed!


I’ve spent a while in April researching info on brushless motors, esc etc. I wish that I had found this thread of yours back then! Anyway I am planning to alter the superstructure (sacrilege perhaps?) to give it a more offshore powerboat appearance.


I quite prefer the simpler Lesro Arrow style and have found some interesting modded versions online.


If I can be of assistance with any dimensions etc? I believe you were after the spacing of the underside strips (forgive my incorrect terminology).

[zooma]

Hi Stuw - nice to have another Javelin owner onboard.

I actually thought that the Javelin was meant to be an off-shore racer ? The cabin cruiser version that used exactly the same hull is the Rapier.

The Arrow is only a smaller version of the Javelin, but I have seen a black and white painted Arrow (on uTube and the Tamiya owners site) that has been given a slight Sunseeker influenced facelift (including the wings) to make it look a little less like an off-shore racer - and more like a Sunseeker!

Last year I found a new LesRo Streaker kit on eBay, I put a bid in for it and won it.  I think this is exactly the same as the Javelin and only the name was changed - so I now have all three versions that LesRo used this same 39" long hull for  - even if two of them (Javelin and Streaker) are actually the same boat.

The Streaker kit was un-touched and still has the plan with it, so I now have the spacing for the strakes - but thanks for the offer of some help with the measurements.

Altering the superstructure sounds interesting - I have been thinking about changing the "superstructure" (or the lack of it!) on mine to a fast cruiser style - more like an up to date and less angular Rapier.

Let me know how you get on - it sounds interesting

Bob.

[Backerther]

Hi Stuw;
I am interested in your looking into the conversion of the powerplant to electric motor for the boat
originally built in 1994.
That is because I also did it about 7 years ago to my 99cm Jupiter F-99 originally built with 60 glow engine
in 1979.
Here are the pics below for your information.
The motor is 3974-2200KV brushless, water-cooled,max current 100A at 18.5V according  to the manufacturer.
ESC is constant current 120A water-cooled also from the manufacturer's spec.
I am using 3 cell-lipo and this is sufficient for my Jupiter-F99 . See the following video for reference.
The coupling is double disk type and not oldham's coupling,see below.


The first pic below is what is at 2014, yellowed due to placed beside the window with no cover at all.


(1) taka's model boat **Mr SKG's JUPITER 2 - YouTube

[zooma]

My Rapier (same hull as the Javelin) has a really impressive performance with a Turnigy 3648-1450.  This is an out-runner motor.


If you prefer an in-runner, the Surpass 3574-2250KV has been on offer on Bangood recently for less than £20, and if you would like it to be water-cooled, a slide-on water cooling jacket is available for another fiver.


Both are anodised in red and look really smart.


This is what I have bought for my Javelin and I am confident that I will not be short of power.


Bob.

[Stuw]

Nice set up and lovely looking on the water.


I haven’t run my Javelin yet as she needs some serious tlc first. I think my prop shaft isn’t true and is vibrating somewhat. Thought I could get a new inner shaft but sounds like dimensions may have changed after all these years and don’t fancy trying to drill out the bearings so may take the step of trying to bash out the old shaft without ruining the boat    ? Any ideas?


I sourced a Dynamite 3674 1900Kv brushless motor (DYNM3915) and Dynamite 120A marine 2-6S ESC both water cooled early last year. Looks like I could have found a cheaper motor if I’d seen this thread! I am going to extend the motor to esc wires myself as they use 5.5mm bullet connectors so that I can locate the ESC somewhere suitable.


I’m planning to run it on 7.4v 2S pack to start with as I didn’t want to overdo it but looks like zoomas Rapier is running 4S and similar Kv motor? Wasn’t sure on max revs versus propshaft. Obviously out of water rpm will be higher but is there a way to estimate running rpm?


I’m trying to work out how to upload some photos. They should appear but are probably very low res as I’m trying to get something up and it’s frustrating!


I’m not satisfied with my forward hatch as it doesn’t quite sit correctly so might create a new one. My initial idea to remove most of the “superstructure” forward of the cockpit (albeit not really much!) might be scrapped and I will perhaps try to keep her as original as possible as there aren’t many about it would seem.


My Javelin doesn’t have a hatch in the centre but I might try to retro fit one.  I want to apply a new paint scheme and plan to spray paint and apply trim tape and add some cleats and fairleads. Planning to create an instrument panel with wheel and dummy throttles to add a bit of detail.


It used to be powered by a Magnum GP40 Ex RC aircraft power plant which I had converted to marine water cooled use by fashioning a water jacket around the head. Worked pretty well.


Haven’t done any model building of this type since I built the Javelin back in the 90s so we will see if the ideas in my head can be translated into reality!


Seeing the info on here has given me more energy and enthusiasm to get on with it! is it just me or is it somewhat time consuming to post on here to avoid spammers and bots?

[zooma]

Thats a nice paint scheme you have there Stuw - bright and colourful - perfect for an off-shore powerboat!

My Swordsman build is taking a lot of my bench time at the moment, but I did take a look at setting my small bandsaw up again with the little jig that I made to cut some more strakes to add to my Javelin and Rapier hulls as neither of them have any strakes fitted.

I restored my Rapier and bought the Javelin on eBay, so I never built either of them from new, but neither builder of the originals fitted any strakes.

The slightly over-size strakes that I intend making will look nice and aggressive (same as I have just fitted to my Swordsman build) - so even if they make no difference to the performance - they will look good!  I think 3 on each side will look "right" but I will check it when I have them cut as being a littler bigger,  two on each side may be enough and look better.

My Rapier is nice and quick when running only on 2 cell 5600mah 65C LiPo cells on our club lake, but on more open water I can change to 3S or 4S (using a smaller dia prop) and it could easily get a bit "silly"

I had a similar problem as you have with the prop shaft on my Rapier - it was an old 2BA size and I fitted an M5 stainless inner shaft - and that did need the old shaft bearing opening-out slightly. If you prefer to change the shaft and fit a new one - this is how I change mine:-

After taking everything out of your hull (including the inner shaft) scrape away any adhesive/filler around the shaft that you can get to, and then give the end of the shaft a sharp bang with a heavy hammer. This usually shatters any old glass fibre/epoxy/filler/cyno that may have been used when the shaft was fitted.

Once loose, you can wiggle it about and remove any fractured lumps of old hardened glue/filler etc until you can withdraw the old prop shaft.  Once the old shaft is out of the hull, you can clean everything up and fit the new M5 shaft. 

As a matter of interest I may still have the old 2BA inner shaft that I removed from my Rapier.  I rolled it on glass to check it, and it still runs straight and true. When I take a good look at my Javelin I will see if the inner shaft runs true on glass and if does and there isn't any play in the bearings - it can stay in the boat. If anything is wrong I will remove it (using the method described) and order a new one from ModelBoatBits to replace it.

You will see that the new M5 shafts have a slightly smaller dia brass outer tube than the old heavy brass tubes used in the earlier 2BA propshafts, so you will gain a little more "wriggle room" to get your new shaft to run straight and centrally in your hull when you fit your new shaft.

Stay safe!

Bob.

[Stuw]

Thanks for all that good info. I shall give it a try. Although the paint job looks good on low res photo it’s nearly 27 years old! I need to patch the side where I put a hole for the glow exhaust and I cut a slot in the forward cabin to assist with air cooling the old motor.


My paint scheme seems to correlate with the stock internet photos of the original box cover. I had added a stencilled “Javelin” to the sides and that’s how I managed to search for similar boats after all these years as I had forgotten the make!


I shall make a proper stand as well as the cardboard box doesn’t look right.

[zooma]

I think your cardboard box stand looks a little better than my wooden ones

If you can save your 2BA prop shaft, all of the M5 propellors will fit it OK.  (As a matter of interest, the smaller 4BA shafts can use M4 propellers too!).

British Associated (BA) threads are a metric thread ("not a lot of people know that") and way back in the 1960's when all our prop shafts were either 4BA or 2BA we always used M5 and M4 propellers and they fit OK.

I have never seen a Javelin box - I will take a look online to see if I can find a picture of one as it may give me an idea for a nice paint scheme !

Stay safe - Bob.

[Stuw]

Hi Stuw;
I am interested in your looking into the conversion of the powerplant to electric motor for the boat
originally built in 1994.
That is because I also did it about 7 years ago to my 99cm Jupiter F-99 originally built with 60 glow engine
in 1979.
Here are the pics below for your information.
The motor is 3974-2200KV brushless, water-cooled,max current 100A at 18.5V according  to the manufacturer.
ESC is constant current 120A water-cooled also from the manufacturer's spec.
I am using 3 cell-lipo and this is sufficient for my Jupiter-F99 . See the following video for reference.
The coupling is double disk type and not oldham's coupling,see below.


The first pic below is what is at 2014, yellowed due to placed beside the window with no cover at all.

I’m not familiar with that type of connector between motor and shaft. Is it flexible at all?


Also it looks as though you have a servo set up to operate a micro-switch near to the motor. What does it do?


Here is a pic of the underside with the strakes that I fitted. I assume I put them as per the plans?

[zooma]

Thanks for the picture of the underside of your hull to show the three strakes per side.

I cannot answer the parts of your question directed to Backerther, but I would suggest that you use a Powerflex coupling from MBB here in the UK - they work well and and have a small amount cushioning (flex).  They also make a solid bar that has the same dimensions as the Powerflex couplings to use as an alignment coupling to fit when you are aligning your motor and prop shaft.

When all of your adhesives that are being used on your motor mounts and prop shaft are dry, and everything is securely fixed in position, this solid alignment coupling is removed and the Powerflex coupling is fitted instead.  I would not run with a solid coupling.

My fast boats have no reverse function on the ESC and no servo operated micro-switch power cut-off. The fewer connectors and joints that you have between the LiPo and the ESC the better to avoid power loss.  I have found one pair of XT90 plugs give a solid and reliable connection between the LiPo and the ESC and being non reversible they avoid any unwanted "shorts" or "reverse polarity" connection mistakes.

The failsafe is set on my RadioLink RC4GS transmitter to close the throttle in the event of any signal loss.

Hope this helps.

Bob.

[JimG]

[quote author=Stuw link=topic=65422.msg711055#msg711055 date=1612195041
Seeing the info on here has given me more energy and enthusiasm to get on with it! is it just me or is it somewhat time consuming to post on here to avoid spammers and bots?

Just be patient for a bit longer Stuw, if I remember correctly the checks stop once you reach 10 posts, you should soon reach that.
Jim

[Stuw]

[quote author=Stuw link=topic=65422.msg711055#msg711055 date=1612195041
Seeing the info on here has given me more energy and enthusiasm to get on with it! is it just me or is it somewhat time consuming to post on here to avoid spammers and bots?

Just be patient for a bit longer Stuw, if I remember correctly the checks stop once you reach 10 posts, you should soon reach that.
Jim

Ah ok. Patience needed! I’m nearly there...

Thanks for the picture of the underside of your hull to show the three strakes per side.

I cannot answer the parts of your question directed to Backerther, but I would suggest that you use a Powerflex coupling from MBB here in the UK - they work well and and have a small amount cushioning (flex).  They also make a solid bar that has the same dimensions as the Powerflex couplings to use as an alignment coupling to fit when you are aligning your motor and prop shaft.

When all of your adhesives that are being used on your motor mounts and prop shaft are dry, and everything is securely fixed in position, this solid alignment coupling is removed and the Powerflex coupling is fitted instead.  I would not run with a solid coupling.

My fast boats have no reverse function on the ESC and no servo operated micro-switch power cut-off. The fewer connectors and joints that you have between the LiPo and the ESC the better to avoid power loss.  I have found one pair of XT90 plugs give a solid and reliable connection between the LiPo and the ESC and being non reversible they avoid any unwanted "shorts" or "reverse polarity" connection mistakes.

The failsafe is set on my RadioLink RC4GS transmitter to close the throttle in the event of any signal loss.

Hope this helps.

Bob.

Hi Bob, again that’s all useful and helpful guidance to reduce the chances of messing it up. I only have the supplied length of wire from the hard case Lipo and then a Deans to XT90 converter to the ESC. From what I have read the wires from battery shouldn’t be lengthened to avoid fire risk and losses but the ESC to brushless motor wires can be extended so that’s my plan.


Another rookie question forgive me but if you can help? My ESC has 2 inputs from Lipo as linked XT90s. I have a loop in one as I only have 1 Lipo pack. Is it possible to connect 2 Lipos and if so does that give you twice the power or same power but longer run time. Again forgive the silly question. I believe you said perhaps elsewhere that you had 2 lipos side by side in your Rapier to allow you to switch them over for longer run time. Can you also connect them together to get the extra power you mentioned?


Whilst I’m at it, is there a way of telling when you are getting low on cell pd before you end up drifting on the lake? I’ve seen a little digital display option for cell pd but not sure how it’s connected in and if it helps.


Not sure why my underside photo ended up stretched sideways! Google images seems to show the Javelin box pic as yellow and orange in the pattern as mine. Only a couple of versions I could find. Lots more of the Arrow in various guises and I quite like the Kyosho Sunseeker version and it’s larger sibling the “Miami Twice” scratch built that I’ve seen. Search google under images for Lesro Arrow and they all come up.

My new receiver unit has the failsafe cut off you mention. I’m amazed at how compact and light the receivers are now. You could fit about 6 into my old one! Is there a benefit to not having the ESC set to reverse apart from preventing unintended selection?


Stuw

[zooma]

If you take a look at the Rapier thread and scroll down on page one, towards the bottom you will see some early pictures of the inside of the engine bay and the next compartment which has become the battery bay.


The engine bay shows the motor in position and if you look at the bulkhead behind it carefully you will see that I have cut a slot in it that is wide enough for the three motor wires (mine have 6mm gold connectors fitted) to pass through into the battery bay at the same height as the ESC that is mounted on a shelf at the same height on the other side of his bulkhead.


The picture of the battery bay shows the cradle that I have made to hold a pair of LiPo cells side by side with a removable wooden bar to tighten down on top of the cells to stop them bouncing about when the boat is on the water.


If you look carefully you can just see the edge of the small shelf on the bulkhead (between the LiPo bay and engine bay) that I made to hold the ESC.  This allows the wires from the ESC to the motor to have the shortest length and should allow any motor and ESC to connect to each other using the manufacturers supplied ESC and motor wires with no extensions being needed.


With the ESC mounted above and so close to the LiPos there is no need to extend the LiPo wires either!  With an XT90 on the LiPo and the ESC I have a good solid connection with the shortest possible wire length so it keep things very simple.


When I refit and rebuild my s/h Javelin I will copy this installation exactly as in use I have found it works perfectly and has been trouble free.


Using a "Y" lead you can double the capacity or double the voltage depending on whether or not it is wired in parallel or in series. Hobbyking (and others) sell XT90 "Y" leads of both types.   Using a battery tray design like the one shown in my Rapier it makes it easy to run two LiPo cells either linked or individually.


Every ESC that I have ever used that was designed for use with LiPo cells cuts off when the battery drops close to the lower safe limit and stops the motor.  After a few seconds the ESC will re-set and allow the boat to be driven slowly (to prevent dropping below the safe capacity of the LiPo).  This has always given me enough power to get the boat safely back to shore.  Some ESC allow you to adjust when this cut-off cuts in - so you can leave a little more in reserve if you are operating at a longer distance from shore. - check the operating instructions for your ESC ( often available inline if the original document has been lost).


Hope this helps to answer some of your basic operating questions?


Bob.

[Backerther]

Hi Stuw;


So nice for me to have your questions on my setting of motorised Jupiter F-99.
As for the coupling I used,this is so called double disk type coupling normally for use of industrial applications.
This is generally flexible against mis-alignment like eccentricity,deviation of angle and endplay,
in addition,high torque and RPM without twist by which it is said to be suitable for universal purpose.


As for servo-switch,it will function the spare battery when a main battery is fully discharged after long sailing
without noticing such battery conditions.
By this switch,the boat is able to continue the sailing for more time or to return safely to the shore I stand.


Normally my boats are equipped with 2 main batteries or 1 main and 1 spare or 2 main and 1 spare battery
depending upon the boat.
In this sense,the servo-switch will work as  long run switch or emergency switch depending on the
case when the boat stops suddenly on the water due to a main battery exhausted.


The following pics are my Najade that has 2 main and 1 spare battery intending a long run sailing and safe return
without taking care of battery conditions so deeply.


PS;A digital V meter is also convenient to know battery conditions to estimate the sailing time in advance
    as well as a kitchen timer around the neck.!! Everything is for a secure recovery.!!