Large Scale Power Systems

Gregor77 · May 21, 2013, 03:49:08 PM

My next project is a 1/3 Sopwith pup.

The manufacturers specs are 28-34 lbs, 108 WS, 45-70 cc gas engine. 2.1-1.27 glow engine. What would be a motor on the market that can power something this size?

battlestu · May 21, 2013, 05:28:06 PM

the king has an 80cc motor:
http://www.hobbyking.com/hobbyking/store/__25410__Turnigy_RotoMax_80cc_Size_Brushless_Outrunner_Motor.html

sihinch · May 21, 2013, 05:50:42 PM

A small child, pedaling?

Frank v B · May 21, 2013, 06:17:22 PM

Greg,

Just take a motor from one of your VW's you have on your property. Should be powerful enough.

If you want to go electric, may I suggest the lawnmower bolted on vertically with a very long cord.

Holy crap- 6600 watts!!! My entire fleet of 40 airplanes don't even total that!!

Frank

thehaze · May 21, 2013, 06:18:49 PM

Is the runway large enough for that size of plane?

Ededge2002 · May 21, 2013, 06:22:10 PM

At 108" I would just land it at buttonville!

Gregor77 · May 21, 2013, 07:40:59 PM

It can be done.

Bobmic · May 21, 2013, 09:04:21 PM

This one will work for sure "Max. Power at Sea Level (Lb.): 53,200-74,100 lbs." .... More than enough.

Ededge2002 · May 21, 2013, 09:23:15 PM

I would use two of those.

Papa · May 21, 2013, 09:59:18 PM

The e-flite Power 160 might do it.

http://www.e-fliterc.com/Products/Default.aspx?ProdID=EFLM4160A

Jack.

Gregor77 · May 22, 2013, 06:30:41 AM

Quote from: Papa on May 21, 2013, 09:59:18 PM
The e-flite Power 160 might do it.

http://www.e-fliterc.com/Products/Default.aspx?ProdID=EFLM4160A

Jack.

Are you sure. The plane is 10 lbs over the recommendation. Would like to have at least 100 watts per pound. I have a similar motor in my 1/4 scales that make me run at 1/4 throttle most of the flight. So maybe that might be ok.

wollins · May 22, 2013, 08:27:45 AM

Greg, one of the things that I'm guessing that will be a bit of a challenge here is also the amount of weight that you'll probably need up front to balance. With that being said, the largest motor that you can afford would be best.

Its been my experience when converting gas/nitro planes that the plane will probably be at least 15% over their stated weight when converted.

Therefore you're looking at about 40lbs give or take.

This calls for least 4000watts based on your stated preference.

So, I'd second Greg H's suggestion (the HK rotomax at 68ozs) or you can go with a slightly more affordable option with the Suppo A7035/9, (called "Cheetah" here) which has the power you'll need albeit lighter by about 10 ounces. (at 58ozs still no lightweight though!)

I really believe that nose weight will be your biggest challenge here hence my suggestion. Something to consider. Just my .02 cents.

Colin

Gregor77 · May 22, 2013, 08:47:52 AM

Ok Collin, thanks for the information. Due to the large Cowl on a Sopwith Pup, I was going to hammer everything in the nose.

My plan was to use 10-12S. Running 2X5S 4000 in Par =8000 mah having two sets, so 4X5S parallel, then putting the 5S-8000 in series making a 10S, 8000. With 4 large 5S4000 packs in the nose, this will help. Worse case I can add another 4 packs if I need more weight. I have more than enough room with a power 160 or a rotomax in the nose. I am hoping to build this one light. Maybe 30 lbs with scale stuff added.