Modified Stiletto project

Started by jbkiwi

48 updates 539 likes 112 comments
jbkiwi #41 of 49

Modified Stiletto project

Have just received the new 45A Surpass ESC and GT Power engine sound system, and have them installed. I had a 6ch RX coming to solve an interference problem between the sound unit and the motor. The sound unit uses a siamesed lead for the ESC and the unit to plug into the RX throttle, but the sound system would go berserk when I turned the water pump on using the previous set-up.

I had the same problem with the Russian work boat, and solved it by using another smaller 3ch RX and plugging the sound unit into the throttle on that. Found with this ESC I don't have that problem, so won't need the other RX. I fitted 3 capacitors to the pump motor, plus a ferrite clip on sleeve to its' power lead, but not sure if it was that or the different ESC which did the trick, but the capacitors had to be a good thing anyhow.

Motor is not as smooth with this ESC, especially at low throttle, - sounds like the timing needs changing so will need the programming card to see if it can be done, (doesn't appear to have the normal manual setting mode,- no instructions for that anyhow.) Most ESCs have the same method of entering the menu, but doesn't seem to work on this one.

I have another few motors I can try which might be smoother if this one gives problems,- 2 nice smooth 1500 kv heli motors with built in fans,- but they might be too fast.

Re the cooling fan which comes fitted under a cover on the new ESC,- this runs constantly with the power on, so I have interrupted the fan power neg lead from the micro JST plug on the ESC, and screwed a 30C thermo switch to the side of the heat sink, so it will now be automatic on-off, and won't waste battery power when sitting still. I don't anticipate things getting too hot with the motor I'm using, so it should do the job.

Still a bit noisy and coggy, but it's not possible to easily rubber mount a motor and keep it lined up. Now need a nice calm day for the test run, (airboat rescue boat will be on standby😉)

JB
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jbkiwi #42 of 49

Modified Stiletto project, first sea trials.

Finally! a decent enough day for a first sea trial. Runs perfectly but the ESC Motor combo has a nasty frequency noise just where you don't want it at slow speed. Wasn't so bad with the 'red brick' one way aircraft ESC, but needed reverse. This Surpass ESC isn't smooth at all at low speeds,- even tried other motors but all similar.

May go to a HV brushed motor and ESC to see if that fixes the problem (hate noise) . I have 2 of those motors in my vintage runabout, and they make far less noise than this lot. Thought the boat sat too high in the water (due to balsa / glass construction rather than lots of ply) which might have been a problem, (torque roll) but with the cable drives' low angle it runs and turns pretty well, (could do with the rudder size increasing for reverse).

Fairly happy with it except for the noise. A bit breezy on the lake to take decent pics, kept sailing down wind sideways at 1kph and wouldn't stay put. Total run distance on the tests was .777km, top speed 11kph, (Sky RC GPS) and 3s 3000mah battery still at 9.8v/cell, motor cool.😀

JB
Liked by PemyslJ and MouldBuilder and
12 comments
  1. ChrisFBronze
    Vice Admiral
    JB - sorry for the delay in replying to your question about my modifications, I missed the post.

    My versions are about the same size as yours at 34.5" and frame construction as well. Picture shows the three versions I've produced drawings for and the other picture is for a further modified one for my water-jet project which I'm hoping to make a start on soon.

    Chris
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  2. jbkiwi
    Fleet Admiral
    Hi Chris, like the jet project mods, makes the boat look very sleek. I'll be watching your build with interest when you start.

    JB
    Liked by Len1 and ChrisF and

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jbkiwi #43 of 49

Modified Stiletto project, another motor change.

Changed to a 37/56 1600kv heli motor, which has an internal fan built into the back end of the can (pic 2). I bought 2 from HK years ago and never used them,- finally found a use for one. Seems to be a bit quieter that the other 3, but you can still hear it cogging/snapping up to half throttle. I think the problem is with the ESC as none of the 4 motors tried will run smoothly, (might be a dud). Might have to try another ESC, as none of these motors had a problem before.

This motor is the best of the 4, so will give it a go on the pond. It can take up to 4s, but I'll try it on 2s or 3s. Only pulls around 6A at max so not too bad,- cruise at around 2.5A, so should get a decent run from 3s 3000mAh LiPo. Sounds a bit loud in the vid with the cabin off, but the camera mic is very sensitive, so not as bad as it sounds,(a bit like a 550 brushed motor) We shall see.

Hoping to do an endurance run up our beach which is 3km long if we ever get a flat calm sunny day, and follow it in my 12ft dinghy. Not many days like that in recent years, plus the tide has to be right to get the dinghy out of the river. A lot of coinciding needs to happen.
If you listen till the end of the vid, you will hear the auto fan turn off when the ESC is 28C.

JB
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6 comments
  1. AlessandroSPQR
    Fleet Admiral
    I'm enjoying this topic and especially Jbkiwi and ChrisF's posts.
    Your tests are very useful and interesting. You do well to share them.
    I will try to memorize as much of the information you have provided as possible.
    Liked by PemyslJ and Razor1955 and
  2. Len1
    Lieutenant Commander
    Just to add something to help tune/adjust an ESC is get a programming card or programming device to tune or easily setup your ESC. It sure make this a easier thing then retrying to keeps track of the number of beeps or flashing light.
    Len
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jbkiwi #44 of 49

Modified Stiletto project, RE another motor change,- No4.

Sounding more acceptable with the cabin on

JB
Liked by Razor1955 and MouldBuilder and
2 comments
  1. Commodore-HGold
    Commander
    That’s a great boat, but it is a little noisy. Have you tried the motor without the speed control? You could try some lower voltage batteries and see if it’s just a motor or is the speed control generating all that noise? Is there anything binding in the drivetrain that overworks to speed control? You could put an amp meter in the circuit and see if the amperage drops when the speed increases.
    Liked by Razor1955 and Len1 and
  2. jbkiwi
    Fleet Admiral
    Comm H, re noise,- the hull is very light and motor is solid mounted, so would be a bit noisy anyhow,- would not be so much with a brushed motors though. The problem is the motor timing and PWM setting is not adjustable with this particular ESC, Some ESCs - especially plane ESCs - have a range of settings so you can get the best performance from a particular motor, ie number of poles, inrunner, outrunner etc.
    Re without ESC, - Brushless motors won't run without an ESC

    Brushless motors don't all run best on the auto settings of certain ESCs, and some need to be adjusted for best performance. On the whole they work ok on most ESCs, but can be improved. The 'cogging' with brushless motors (mainly outrunners) is when the motor is struggling to pull the rotor across the poles at low power, (a bit like an iceblock stick in your bicycle spokes,- sounds smoother the faster you go) . This is more noticeable in low pole count high kv motors with strong magnets, which don't like running at low revs, (unless the magnets are weaker)

    Sometimes this can be reduced by adjusting the ESC to suit the motor better. Lots of things can affect performance, like number of turns, number and strength of magnets/poles, diameter, length etc, so a good adjustable ESC is a good option. The chart is from an aircraft ESC and shows the possible adjustments (last 2 sections)
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jbkiwi #45 of 49

Modified Stiletto project, a few refinements

Did a bit of tidying of the wiring, removing bits etc (not that you'd notice) added a thermostatically controlled turbo fan at the front of the motor, - run from a UBEC off the main battery, repositioned the sound module, repositioned and raised the cabin 'floor' and added magnets. I've also made a cut-out in it for the sound unit.

Added a couple of small guides on the inner comings at the stern as well, to make fitting the cabin easier. Cabin only fits in one place exactly, and was a bit tricky to get on. Just used small blocks with tabs of acetate sheet plastic, bent inwards. 4 magnets hold the cabin down. Just making a few small refinements while waiting for some decent weather.

JB
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jbkiwi #46 of 49

Modified Stiletto project, success !

Running well now with the new heli motor. Small temporary prop (35 diam) on the 1500kv motor lets it go slow enough, but also has good speed (24kph/13knots on the GPS) Throttle end point is only at about 75% so plenty of room for 'ridiculous mode' - also can go with a bigger prop and bigger battery (motor is for 3-6S LiPo and 55 A max) - no real need though as it's more than fast enough like it is.

The new ESC (45A) overheated at one point, at only around 8A! and turned itself off for about 30 secs till it cooled down, then came back 'on line' and was away again. The output from the ESC is erratic as you can hear, so have ordered another 60A ESC to see if that will be better. Noise is actually not any worse than my vintage runabout, with 2 high voltage 550 brushed motors at a similar speed. The cables are in a plastic tube inside a brass outer, and are greased, but can flex slightly and make a bit of noise (unlike a solid shaft) so could be where a bit of the sound is coming from,- plus the motor being solid mounted, -but a 90% improvement over the first motor. Anything going fast will make some noise anyhow.

Still a bit coggy at low revs , but good enough for now, (might improve with a different ESC) Still may need a bit of tweaking here and there, but nothing major. Hull runs perfectly with the shallow angled cable drive and corners well. Still 3.8v/cell in the 3s 4000mah LiPo after a number of fast runs and cruising around for about 20 mins. If I went to 4s, I could dial the throttle back quite a way and still get the same speed with less voltage loss. Plenty of options with electrics.

JB

one of todays runs.
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7 comments
  1. jbkiwi
    Fleet Admiral
    Hi Ian, I don't think there is a full scale version, as I think it was originally just a Lesro designed model kit from the 60s. Hull does look a bit reminiscent of the old Donzi powerboat designs (like Surfury) from that era, so maybe the idea might have come from the early powerboat racing days.

    JB
    Liked by Len1 and hermank
  2. ChrisFBronze
    Vice Admiral
    Certainly is a success JB. Looks great on the water and being a bit bigger sits well and isn't adversely affected by ripples etc. and handles very well with a good wash.

    Chris
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jbkiwi #47 of 49

Modified Stiletto project, ESC experiment

Thought I'd have a go at converting a brushless aircraft ESC to having forward and reverse. I've found that the aircraft ESCs perform better than the car ones, and usually have more tuning options, including timing and PWM changes. managed to get a set-up working, using a double gang on-on switch and a Red Brick 50A ESC (also with an RCS 30A).

The switch is cross wired (X) between opposite terminals and fed to the center terminals from the ESC output. Only 2 motor wires go in and come off the switch, with a bypass wire for the 3rd motor wire from the ESC. This wire is the same length as the combined cross wires and output wires to keep all the wires the same length. I've used a servo to switch the direction, and everything now works from stick to the bottom for 0. Throttle is from the bottom forward as with a plane, then back to the bottom, switch over to reverse and forward again for reverse.

Switch is a 240V 20A which is plenty for this setup with moderate speeds. The 30A ESC got a bit warm, (with no cooling) but the sun was blazing and the temperature of most things inside the boat was 32C + for a start. Changed to the 50A ESC and it stayed cool enough without a fan also. Both the plane ESCs ran the 37diam heli motor smoothly and ran very slowly with almost no cogging (noise is just the bearings in the motor amplified by the hull and very sensitive mic on the camera) actually sounds like a brushed 550 motor,- very quiet, You can see the difference with the 45A Surpass car ESC in the 3rd part of the in boat vid (ignore the sound unit, should have unplugged it) which has horrible cogging/snapping at low revs,

Built the complete unit after the boat test and tried that out, and it all runs perfectly. Looks a bit agricultural but thought I'd give it a go as I've never seen it done before. The aircraft ESCs are generally a lot cheaper than the car/boat ESCs, and are easy to add a fan to if necessary.
Could be made more compact, but this is just a prototype, -keeps the braincells moving😀🤓
JB
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jbkiwi #48 of 49

Modified Stiletto project, (another new ESC)

More changes than a womans' mind, 😀 Now have the Hobbywing 60A brushless ESC installed and tuned in. Works very well, - much better than the previous 45A Surpass rubbish, -should be at twice the price (but only 3/4 the size). Runs smoothly and quietly with virtually no cogging at low revs. I need to find a way to give it a wider center dead spot, (mainly to sync the sound unit start to the throttle start), as the largest one in the settings is not very wide (almost non existant) Probably could get round it by using the 'double tap' setting for reverse, but that's always a pain and a bit hit and miss, (don't want to be flying at the jetty and miss reverse☹️)

This ESC has timing settings if you need them (can give more torque and revs if needed) but better left on the std setting (0 deg) initially. Turned the throttle end point back to 50% on the TX for economy, but will make final settings for a sensible speed on the water.

Recorded some air horns with my video camera, converted the vid to MP3 and added it to the sound card in the on board stereo. Works quite well, (now need to make some trumpets for the mast) Pretty much finished now apart from a few detailing items (anchor etc). Now waiting for a flat calm, sunny day, with the right tide for launching my dinghy, and the outboard running well (not too much to ask?) and I might try a sea endurance run.

JB
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6 comments
  1. jbkiwi
    Fleet Admiral
    Len, regarding the dead spot, I managed to get the sound unit synced to the motor/throttle by resetting its' center and resetting the ESC, (everything zero'd again on the TX) but still had a narrow dead spot. The ESC is set to the widest spot which is still a bit narrow, and seems to be biased towards reverse, (dead spot seems to be more into fwd stick movement but just a fraction past center before reverse light is on)

    What I have tried now is setting the ESC to fwd/brake/rev mode and using the 'double click' option for reverse. It's not the best as you have to be in fwd, go quickly back to rev so the ESC detects the change - (green and red light flash) with around 3/4 reverse stick, go just into fwd then back to get reverse. Not advisable to be racing at a jetty and expecting a quick reverse with this mode, as it's not guaranteed to work 100% first time, and might need a few tries.

    It does have the advantage of giving you as big a center as you want if you just leave the stick exactly in neutral, and when you are ready, fwd-back-fwd-back.
    The advantage of the reversing switch I made, is that none of this is necessary, - just fwd-center- switch -reverse,- the stick is just dead past the center on the 'unused' side until you switch it over, then the opposite applies.

    Haven't tried changing the ESC back to just straigh fwd/rev yet, but will try it when I have a minute. You could probably solve the problem using a centering stick for the throttle, but that might be a pain to use.

    JB
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jbkiwi #49 of 49

Modified Stiletto project, RE (another new ESC)

Finally had a decent day to test the new Hobbywing 60A ESC on the pond. A big difference between this and the 45A Surpass ESC as there is no cogging and it runs smoothly through the throttle range without missing a beat as it did in the tank. Seems like an excellent ESC. Throttle is limited to about 70% but might cut it back some more, as it is unnecessarily fast.

Managed about 25 mins of running fast and cruising on a 40000mah 3s Lipo, so not too bad. Maybe up to an hour if I just pottered around. I also replaced the infra red pickup extension under the radar (for the stereo remote) as the previous one had died, so that's back to working.

JB
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7 comments
  1. jbkiwi
    Fleet Admiral
    No idea sorry Nick, you might have to make them or modify something from Cornwall Model Boats

    JB
    Liked by hermank
  2. ChrisFBronze
    Vice Admiral
    They are in the UK but ShipWrightShop do some one ball stantions of various heights that could do the job.

    Chris
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