jawsmon

My Feedback: (7)

I'm in the planning stage to set up an electric conversion for a J-3 Cub on floats.
This bird has an 84" wing span and a 52" long fuse.
Any suggestions for a motor, batteries etc.?
Are there any major concerns about a little water contact from the spray off the floats other than it makes for good cooling?


Jawsmon

Man says show me and I will believe...God says believe and I will show you.

normgoyer

I too am wondering about water and electrics, anybody have any experience? Norm

algutkin

My Feedback: (1)

I am also into RC boating, some pretty big ones.

Electricity can travel through water, thus, if the ESC gets wet there is a good chance that the ESC will short out. In additon, there is a good chance that the Lipos would short out also. I have hearing aids, which when get the slightest amount of moisture, short out. It takes hours in the hot Arizona sun to get them to work again. My boats run on sealed airplane starting batteries, you know the ones that are used to run your Sullivan starter. Others are run on NIMH batteries, in either case, the batteries are not a real problem, even if the leads get wet, or the batteries are dunked the batteries are not spoiled. Lipos are big question mark. I just got my son an electric boat for the holidays, everything is sealed, as this boat might flip over and fill with water.

The gas boats have sealed boxes for the electrics, servos and ESC. From what I have read, float planes will work well on electric, as long as the electrics are inside a sealed box just like the boats. Some servos are waterproof and I wouldn't worry about them very much anyway, they probably will be fine, even if dunked under water.

Electric motors can run after getting wet, as a matter of fact, some of the brushed motors are run under water to break them in. I followed the instructions and did this many times. Brushless motors don't need to be broken in like the brushed, however, I can't see any problem with them getting wet other than a bearing freezing up in the future.

The bottom line, it can be done very easy, and had been done by others. Build a box for the ESC, and spray the servo cases with special spray, the only risk is a bad landing and dunk underwater. Other than that, the above precautions will enable you to convert anything to electric.

I might mention, that a nitro motor will not run with water in the carb, electric will run fine if the motors get sprayed.

Al

jawsmon

My Feedback: (7)

Thanks for the responce Al,
What are the issues with putting the ESC in a box? Are there any concerns about overheating?

Would silicone grease (the type that's used on auto spark plug boots) be good for electrical connections/ plugs?

Jawsmon

algutkin

My Feedback: (1)

Good Question,

The ESC is just one big circut board with some components soldered on. If any part gets wet it will short out, not just the wires. I guess the guys that fly float planes just take their chances with the ESCs. Perhaps they put them in an area that will stay dry under normal circumstances. If the plane crashes on landing, it probably won't sink, but, the electrics will probably be damaged. The weird thing about circut boards, they get wet, short out, then when they dry out, they work. My hearing aids are a prime example. Somtimes I wear them while swimming, then I forget they are there and get them wet. Everything gets very quiet, but, after hours in the dry air, they are good as new. Had the same luck with an RC receiver. Perhaps its because those items are low wattage items. Now take an ESC, an ESC passes the battery wattage on to the motors, this current can weld if the wires are shorted.

I'm surprised that nobody with a float plane responded. You might do a search, as I remember reading about a Seawind that was converted to electric. I guess what I wrote in the first paragraph guys with electric float planes just do their best to keep things dry and take their chances. Like I said, the motors can get water sprayed on them without a problem.

Al

Team Fine Design

Well,I have been racing fast electric boats forever and we deal with this problem every time we put a boat in the water.Our solution has varied from building a water tight box to just sealing up the controller with a conformal spray on coating.We have water cooling built in to take out the heat once they are sealed.
I would design the speedo to be installed mid ship.Not in the bottom,not in the top but somwere in the middle of the fuse so that in the event of a blow over or nose dive the natural flotation would keep the speedo safe.
As far as the motor.I have a Hacker A6014L outrunner that has been wet a few times and as long as I blow the motor out.It is fine.No rust on the magnets and just put a little oil on the bearings.
Unless you are a terible pilot I realy wouldnt worry. As far as the the lipos thats pretty EZ.We just dip the open ends in liquid rubber.(like what you use to repair plyer handles and such)This works very well in keeping the moisture out with out creating much excess heat.
Hope this helps.Dennis

normgoyer

Thanks Dennis, those tips helped me. The liqid rubber looks like a good idea. I am almost ready to launch my 1/4 scale Super Cub with a big AXi motor on scale EDO floats. Norm

jawsmon

My Feedback: (7)

Team Fine Design,

I really like the liquid rubber idea for the battery. It sounds as though this conversion should be fairly easy. Most of the tips seem to be pretty much common sense type ideas. Thanks for your responce.

Norm,

What are the specs on the motor, batteries, etc. that you're using on the Super Cub?

Jawsmon

normgoyer

Hi, the motor is an AXi 5330 F, 90 Opto Jeti ESC, 6 volt receiver and servo battery, 4,000 mah 14.8, two in series for almost 30 v0lts and am starting with a 20 X 8 prop and see how it goes. I am flying it first with wheels then floats when the rains come and we have water in our desert. I have flown the plane before with a Quadra 35 and it was overpowered for a Super Cub. I am taking pix as I go along and will make them avail for any that are interested. Next in line is 1/3 scale Fokker D=VIII with one of the new big motors from e-fight or the even larger AXi with the big bearing plate. Norm

algutkin

My Feedback: (1)

Hey Norm, you know, and I know, there is no surface water in Apple Valley. When it rains the ground sucks it up immediately. What lake in Apple Valley would you fly a float plane at? Puddles don't count.

Build a lake and they will come... I heard that somewhere.

Al

normgoyer

Hi Al, at the foot of Deep Creek dam in the spring there is a nice round pond that we have been flying off for years, it is usually wet enough for about 2 months. Also Mud Lake behind the mountains just to the east of APV wets up pretty good in the spring. One year I even flew a float plane off the snow we had that last about 12 hours. Norm

algutkin

My Feedback: (1)

Norm,

It looks like there will be no problems or moisture considerations when flying a float plane in Apple Valley. Five inches of water will still enable the plane to float and still enable the pilot to experience the thrill of flying a float plane, yet nothing has a chance of getting wet.

The best part is, that should you run the batteries down and the ESC shuts off, you don't even need waders or an inflatable boat to retreive the plane. If I was planning to fly floats in Apple Valley, I'd also have a Golden Retriever dog, aka Float Plane Retriever.

PS. Please feel free to correct any spelling errors, just don't point them out to me I embarass easily.

Al

algutkin

My Feedback: (1)

On a serious note. I found some threads on the Tower Hobbies (or is it Great Planes) Seawind. It appears that the builders do nothing to waterproof the electrics. Their is a technical note in the manual about not being able to use the plane in the water if retracts are installed. However, one guy came up with a simple fix for that.

Evidently, the nose weel compartment was not waterproof, something about the plane flooding through the push rod hole for the retracts. This guy simply used one of those rubber flex hoses that go over a RC boat's rudder push rod to keep the hull dry. It looks like a rubber accordian, I have these on all my RC boats. Another term would be watertight grommet.

Anyhow, the Seawind or Cub on floats looks like a good project for summer flying at Lake Mohave, part of the Colorado River system of lakes. It would also work well if the desert dry lake bed got flooded after a rain storm.

Al