DofE project Precedent Perkasa

[michael scatesParticipant @michaelscates81058]

Hello all

Well where to start. First off hello. My back ground is model aircraft which I build & fly large electric to large four stoke nitros.

My daughter has undertaken for her DofE to build a model boat for her Skills section.

I can only advise on the build but she has chosen the President Perkasa 37" wooden hull.

I posted up on RCME which is my usual forum and it was suggested to post on here.

We are at the stage of deciding the electric motor. Now I fly and understand brushless setups. From the instructions it suggests using a 700BB can motor.

What I need is a help which suggestions on an alternative brushless motor & which esc with reverse for this type of boat.

I have a range of lipos that I can use from 3s to 5s.

Thanks Mike

[michael scatesParticipant @michaelscates81058]

[ads90Participant @ads90]

Hi

I have just completed my Precedent Perkasa 37" and have used the Graupner 700 Turbo motor which is rated for 12 volts. I have used 2 x 6 Volt SLA's (cheaper than Lipos and I don't trust lipos) wired in series for 12 vots. I have used the Tornado Speed control which is 50 Amp rated and sells for just under £30 on the Howes website. The ESC has reverse rated at 20 Amp.

I have used a plastic 45mm X type 2-blade prop and performance is good and realistic and gets up on the plane but battery only lasts about 20 minutes.

A friend of mine has built the same boat and has installed an 800 motor in his and uses the same ESC and battery setup as me and his boat's performance is very fast and better than mine but has had to add a full width trim tab to keep the bow down as he gets too much lift.

Alan

[Dave MilbournParticipant @davemilbourn48782]

I would not advise anyone to fit SLA batteries into a planing hull like Perkasa. Quite apart from the weight problem they are incapabe of supplying sufficient current for a decent performance and you will only obtain about half of their rated capacity e.g. a 7AH SLA will only give you about 3.5-4AH when treated like this.
If you have 3S LiPo batteries then use those, in conjunction with a 12v BB Turbo motor and a low-voltage monitor, or fit a NiMH pack at the very least.
For brushless you would require a motor similar in performance to a "nitro" 0.32-0.40 (we used to call them glowplug motors, remember?). Water-cooling is mandatory (usually via the motor mounting bracket). The very first 37" Perkasa had an HP 40 F R/C glow-motor and went like greased weasel pooh.
Dave M

[michael scatesParticipant @michaelscates81058]

Thanks for the info & advice Alan & Dave.

So as we are planning to use my stock pile of 3S lipos for the boat the 12v BB turbo looks like a good choice. I assuming you mean the 700 12v Turbo BB

Dave what type of prop would you suggest with the Turbo motor for this boat

So the next question is the esc, Of course having reverse is needed. Any suggestions for one supports lipo batterys.

Mike

[Dave MilbournParticipant @davemilbourn48782]

Mike

The 700 12v BB should be fine with something like a 45mm 3-blade scale type prop. I hesitate to recommend any ESC apart from ones I know. This one apparently has an auto-cut off for LiPo batteries, but some of their other ESCs are also prone to blowing up occasionally for no apparent reason. You pays your money etc **LINK**

Dave M

[michael scatesParticipant @michaelscates81058]

Dave.

Thanks for the link, that ese looks as good as any and the reviews look good.

So if I go with the suggested motor and esc with a 45mm fan can you suggest what type of prop shaft I will need to match the motor.

I would imagine that I would need something around 9-11" shaft

Sorry for all the question but we are building adhoc as we go.

This is my daughters build Thread here

Mike

[Dave MilbournParticipant @davemilbourn48782]

The prop shaft should match the boat rather than the motor. I'd suggest a shaft of 4mm diameter. Mark's Model Bits can supply both a decent shaft and suitable coupling; all they need to know is the length of the prop tube between the rear of the coupling and the front face of the prop. They also do some very nice aluminium mounts for Speed 700 motors. Mark has a website here **LINK**

Dave M

[michael scatesParticipant @michaelscates81058]

Thanks Dave, I will have a look at the site and contact them.

Mike

[Author]

Posts