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Old Nov 12, 2001, 02:20 PM
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Woodland Hills, CA
Joined Nov 2001
3 Posts
P-47 Razzorback 90" WS

I am considering building a 90" WS P-47 from Northwest Hobby Technologies as an electric project. I am new to electrics, having flown glow, gas props and jets mostly. My past few attempts with off the shelf electric projects have been very so so. Anyways, this P-47 will have a wingspan of 90" and they say the finished weight with a Zenoah G62 and several coats of automotive paint is between 18 and 20 LBS. The total wing area is 1600 sq. inches. The question I have is what types of electric motors are out there that can power this plane and how much weight in batteries would I have to carry for this plane? I do plan on putting retracts on the plane, weight permitting. Any help or suggestion would be appreciated.

Thanks in advance
Sung
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Old Nov 12, 2001, 03:11 PM
ARFs make me BARF
mrittinger's Avatar
United States, MI, Roseville
Joined Dec 2000
8,809 Posts
Lets see...fighter performance needs 100 watts per pound. 20 pounds= 2000watts! Yow!
Anyone got ideas for this?Might use a couple Astro 90's geared together or something.

Why do you want to go so big on your first electric?Nothing wrong with it, just curious...

Better bet might be the 60-90 size Top-Flite Jug first...Just my thoughts.

Good Luck if you do try, I'd love to see it work!
Look on some of the German elecreic websites,they fly rather large ships with Epower.

mark
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Old Nov 12, 2001, 09:26 PM
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Oak Harbor, Washington, United States
Joined Jan 2001
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Another rule of thumb is to divide wing area by 35 to determine number of cells needed for high performance flight, or 50 for trainer type flight. At 1600 Sq. in. that comes to 45 cells. It's been done but it's not easy or cheap. Do a search on "Giant Scale" and see what turns up. I belive the plane your talking about is largly built of foam. It can probably be built light for its size. Also, that G62 must weigh about 6+ lbs. You can build electric powered airframes lighter than you would for that G62 because you don't have any vibration to deal with.

Good luck with your project. Not very many have have built that large a project outside of Europe. There is a web site in England that has many giant E-power planes listed on it. I don't have the URL handy, but I think you'll find it on a search on this site for Giant Scale.

Norm
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Old Nov 12, 2001, 10:49 PM
D.G.B.
KOMET 44's Avatar
Southington, Connecticut, United States
Joined Jun 2000
2,951 Posts
rojek,look at the maxium motors .there is a special proto type motor there, big and round. Dr. Keith Shaw use's it in his Fokker DVIII.It will swing a 22" prop. then look at the price! $800.00 plus a speed control also do a search for ACTRO motors.these are another special motor that will swing big props without a gear box.built in germany by the kohler brothers(i think) Also Mr. shaw flys a 80" bearcat but its only 8lbs?.. 45 cells =5.6 lbs of battery weight.i will agree start with a T/F jug and see if you like it.when i fly i normally bring 3 flight packs to the feild.45x3=135 .better you than me..........stefanP


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Old Nov 12, 2001, 11:48 PM
Flying electric since 1986
Mark Wolf's Avatar
USA, IN, Brownsburg
Joined Oct 2000
1,764 Posts
IMHO, I would pass on this project for a first electric model.

I've got a few large electrics, a 1/4 Ryan STA, 27% Extra 300, and I'm currently building a 1/10 B-17. With the current state of things, large electrics are really done by people wanting to push the envelope. IMO, they are not quite ready for the masses, much less an electric newcomer.

While it is certainly possible to fly the Jug electric, I'm not sure you'd want to. You're going to spend a ton of time/money for a warbird that won't fly with the same gusto as the gas version. I'd guess the best you'd be able to manage is 4-5 minute flights (if that) and you'll probably be limited to only 2 or 3 flights a day because even if you could afford multiple battery packs you still have to let the larger motors cool between flights.

Having said all that, if you still want to pursue this I'd get in touch with Tom Hunt at Modelair-tech. He has put together a few power setups in this range before and should be able to hook you up with a belt drive that can gang 2 large motors to a single prop.
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Old Nov 14, 2001, 10:05 AM
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Woodland Hills, CA
Joined Nov 2001
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Thanks to all who have replied. I gather that it is possible to get a large Jug up and flying and flying fairly decent. I have order the kit and when it arrive I will proceed to build it. Depending on what the weight of the fuse and wing comes out, I will decide then whether to go gas or electric.

Sung
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Old Nov 14, 2001, 08:25 PM
D.G.B.
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Southington, Connecticut, United States
Joined Jun 2000
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Checking the weight

Rojeck,if you can weigh all your parts.one easy rule of thumb is that plane its self needs to be half the totale flying weight.this don't include the motor,battery,or electronic's.hope this helps.stefanP


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