Super Comet PT50, Need brushless suggestions and other thoughts - Page 3 - RC Groups
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Jun 13, 2017, 10:06 AM
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Gun Tech's Avatar
I hear you, this was a step taken after much internal wrangling. I have tried to shy away from a new battery type, but in this situation it is the best choice due to weight and run time. I agree that most of the failings seem to be operator induced, but the risk is still present even with caution. These are the risks we have to weigh against the gains. We'll see what happens. At least I am starting with new batteries and a contemporary charger, so hopefully the technology will be up to snuff to keep me from being the next YouTube Fail video.

Mark
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Jul 11, 2017, 04:27 PM
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Gun Tech's Avatar
Greetings,
I have been gone for a couple of weeks and couldn't post. The day before I left, we had a regatta here in San Diego and I got the chance to explore the behavior of the PT-50 with the Lipo batteries. It ran great and ballasted the same, however after about 10 minutes on the foils at more or less top speed, the boat stopped dead in the water. While waiting for it to drift to the shore, I kept checking to see if it had gone into battery cut-off and would limp in under its own power. After about 5 minutes it came back to life with full power, I brought it in and checked it. The motor was hot and I gave it some time to cool down. I kept the batteries in it and put it back in after about 15 minutes. It ran just as strong as before and again went for about 10 minutes and shut down. I let it drift to cool again and it came back to life after another 5 minutes or so. Long story short, I got about 40+ minutes running with two batteries, swapped them for another pair and got about the same. The same thing happened the whole time with both sets of batteries, with about 10 minutes running before it went into a thermal shutdown. Obviously the motor is letting me know I need to add water cooling. This leaves me with a decision, should I machine a water jacket for the Orion, or should I get a motor and ESC already set up for cooling? I think I might see about retrofitting one of those rudders with the cooling intakes from a race boat to avoid a plumbing mess mounted to the foil area. Overall I am extremely pleased with how it runs and performs, just this hiccup with cooling is the only item that I would like to remedy. My only concern will be how much weight the cooling jacket adds and how detrimental to ballast it will be. This will be a back-burner project since it's working well for now and I just have to keep from running too hot. I will admit, I pushed it hard to see if I could induce a major failure and it didn't do me wrong. On a different note, I received a shipping notification for a package headed my way from Germany, so the wait begins for the next adventure in hydrofoils .

Mark
Jul 12, 2017, 02:35 AM
Super BRO Bro..........Bro.
RaisedByWolves's Avatar
Looking good so far.

IMO you would do better with a separate motor and esc, with both being water cooled.

The cooling coil can be made out of aluminum tube formed around a D cell battery and really wont weigh much.

Also, most of the issues you have heard about with the lipo batteries have been eliminated through both battery and charger design,

Whatever charger you use I would recommend always balance charging to eliminate battery damage and lenghten the life of the cells.

Also I think I saw a tamaya connectir in there. I would ditch those and get something more reliable and having less resistance.


Get someone to shoot the video for you next time, I really like seeing these in action.
Jul 12, 2017, 08:45 AM
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Gun Tech's Avatar
RBW,
I was thinking about machining a jacket to have direct water to metal contact with the body of the motor. Corrosion would always be a concern, but with consistent fresh water flushes, I think I could keep the salt water at bay. I have seen the coil style, but for some reason the efficiency seems questionable to me. As I was familiarizing myself with the Lipo batteries and the Venom Duo charger, the mystery of Lipos seemed less daunting. It does have the balance feature and seems very user friendly to avoid a catastrophic OOPS! The Tamiya connector was part of the Nimh battery I initially tested with. The wiring is a mix of Deans connectors and Traxxas. I know one of the guys shot video when I was at the regatta, but have to see if I can get a copy to link here.

Mark
Sep 10, 2017, 01:44 PM
Registered User
I'm in a similar situation with a PT-50 and could do with some help please! I started a thread here:

PT-50 rc hydrofoil restoration help needed!

Many thanks

Andy
Sep 11, 2017, 12:55 PM
Big Boats Rule!
boater_dave's Avatar
If the motor is getting too hot, you are loading it outside of it's designed power rating. Is increasing the power of the motor possible? Possible prop swap? I would consider that before adding a water cooling system. Ultra hot FE racing requires water cooling because they are always operating outside of the designed power rating. Your boat just needs scale fast speeds.

Dave


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