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Old Apr 19, 2012, 06:41 AM
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Washburn,ME
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PT-19 Quarter Scale

I have almost finished my quarter scale PT-19 which I am a little disappointed in because of the weight. Boy, I can build tail heavy. This bird has a 9 foot wing span, 84 inches long, 1834.41 sq. inches of wing area, and a wing loading of 40oz. I installed a DLE 55 in the nose and am hoping there's enough engine to do the trick. Don't plan on doing any 3D stuff and would appreciate your comments on the engine selection.I ended up with 4lbs of dead weight in the nose for balance.
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Old Apr 19, 2012, 07:43 AM
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United States, TX, Leander
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Whats the total weight? My calculations must be off, I came up with about 45lbs total weight? That cant be right.
Edwin
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Old Apr 19, 2012, 07:52 AM
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Washburn,ME
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Pt-19

It weighs 32 lbs plus or minus as I used my bathroom scales.
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Old Apr 19, 2012, 08:16 AM
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Been so long since I calculated wing loading, I got all turned around.
I would say you're a little on the edge. It will definately be flying on the wing and would probably be ok. But in an emergency, there might not be much room for emergency power. A G-62 with an electronic ignition would have been my choice. But then I'm partial to G-62s. I would fly your setup and see how it does. I know you can fly with a power to weight ratio of .7:1. You're probably in that ball park.
Edwin
PS - I wouldnt worry too much about the amount of weight added. I had to add 5lbs of 1/4" steel plate to the firewall of a 76" corsair to get it to balance, total weight was 20lbs. I thought it was a led sled but it flew good. Just had to manage the landing better.
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Old Apr 19, 2012, 09:25 AM
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Washburn,ME
Joined Jul 2008
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Edwin1, thanks for the words of confidence and I, like you like Zenoah engines. I have a G-45 on a bipe I desined and built. Been measuring for the G-62 and see where Horizon Hobbies is out of the electronic ignition types. Oh well, we will fly her as is and see what happens.
Frank
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Old Apr 19, 2012, 11:17 AM
Scale Builder
United States, AZ, Litchfield Park
Joined Jul 2002
2,530 Posts
Your weight and wing loading are fine in my opinion and I think it will be quite the floater actually. Power wise I agree with Edwin in that the 55 will not be too much but it will certainly fly the airplane and will probably provide better than scale performance. My .02 cents anyway, good luck with it.
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Old Apr 19, 2012, 11:41 AM
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Washburn,ME
Joined Jul 2008
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Chad, thanks for the post. From what my test pilot and others have said, I think we'll be okay . Won't get her out of the basement untill after the 8th of May. Have a trip to FLA to do first. Then it's a couple engine runs, recowl, and head for the field and taxi test. Almost want to cancell trip to Florida. I would get shot for sure. LOL
Her's a picture in travel model-exceot for the cowling.
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Old Apr 19, 2012, 11:46 AM
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Which kit is it?
Edwin
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Old Apr 19, 2012, 11:58 AM
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USA, ME, Caribou
Joined Nov 2006
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Frank,
Lookin good. I think we will be fine with the 55, it will have somewhere in the neighborhood of 28-30 lbs of thrust with the 22x10 prop and should fly fine. It will be flying on the wing and will need to be flown scale. I run some taxi tests with it before we do any actual flying to check the gear out well.
Can't wait to get into the air this spring!.
Jeff
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Old Apr 19, 2012, 01:47 PM
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Washburn,ME
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Edwin, this is totally scratch built from drawings I generate in November of last year. Of course on any scratch built you run into things that you never thought of and I tried to redraw as I went along. There is a lot of felt tips and paper on this one. I took over 75 photos when building. According to how she flies- I may offer the plans once re-drawn.
Frank
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Old Apr 19, 2012, 03:28 PM
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Outstanding!
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Old Apr 21, 2012, 04:57 AM
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United States, MO, Springfield
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DLE engines are lighter then Zenoah and imo make more power for the displacement
i wouldnt worry about the engine that much
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Old Apr 22, 2012, 03:51 PM
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United States, MD, Elkton
Joined Oct 2011
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My rule of thumb for a decent flying airplane is 12 lbs per cubic inch ...you're good-that airplane is a "Piper Cub" with a low wing.
That means 'adequate' power....not just enough, to move about the sky.
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Old May 20, 2012, 03:29 PM
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Washburn,ME
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Flight day

The PT-19 made it's maiden flights today and was pretty much uneventful. Jeff,my test pilot, did an excellent job of flying and landing her.. Minor trim adjustments, elevator/flap mix, and a steering problem was the only concerns. The use of full flap on landing was a great inmrovement on the second landing. DLE 55 is more than enough engine on this big bird. Thanks again Jeff, and a special thanks to Dale for helping me in the drawings and building of the PT. First pic is me installing the flaps.
Frank
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Old May 20, 2012, 04:16 PM
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United States, MD, Elkton
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It's great when it all works out.Congratulations. Nice looking bird.
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