Toronto Electric Model Aviation Club Forum

Toronto Electric Model Aviation Club (TEMAC) => Building / Construction => Topic started by: Gregor77 on May 21, 2013, 03:49:08 PM

Title: Large Scale Power Systems
Post by: Gregor77 on 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?

Title: Re: Large Scale Power Systems
Post by: battlestu on 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 (http://www.hobbyking.com/hobbyking/store/__25410__Turnigy_RotoMax_80cc_Size_Brushless_Outrunner_Motor.html)
Title: Re: Large Scale Power Systems
Post by: sihinch on May 21, 2013, 05:50:42 PM
A small child, pedaling?
Title: Re: Large Scale Power Systems
Post by: Frank v B on 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. ;D

If you want to go electric, may I suggest the lawnmower bolted on vertically with a very long cord. 8)

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

Frank

Title: Re: Large Scale Power Systems
Post by: thehaze on May 21, 2013, 06:18:49 PM
Is the runway large enough for that size of plane?
Title: Re: Large Scale Power Systems
Post by: Ededge2002 on May 21, 2013, 06:22:10 PM
At 108" I would just land it at buttonville! 
Title: Re: Large Scale Power Systems
Post by: Gregor77 on May 21, 2013, 07:40:59 PM
It can be done.
Title: Re: Large Scale Power Systems
Post by: Bobmic on 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.
Title: Re: Large Scale Power Systems
Post by: Ededge2002 on May 21, 2013, 09:23:15 PM
I would use two of those.
Title: Re: Large Scale Power Systems
Post by: 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 (http://www.e-fliterc.com/Products/Default.aspx?ProdID=EFLM4160A)

Jack.
Title: Re: Large Scale Power Systems
Post by: Gregor77 on 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 (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.
Title: Re: Large Scale Power Systems
Post by: wollins on 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.  ;D   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.  ;D 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 (http://www.bphobbies.com/view.asp?id=V450327&pid=B3675242)) 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   
Title: Re: Large Scale Power Systems
Post by: Gregor77 on 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.