Biplane design

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steve-lima

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Joined
May 28, 2006
Messages
16
Location
lake Station indiana
Hello all . I've been building a Marquart Charger but money is tight at this time so I've been keeping busy drawing and Biplane design that has been in my head lately. It is very small all wood plane. It fits in a two car garage with wings on. I'm wanting to power with a modified Briggs and Straton 18 horse power v twin vangard engine. I know some of you are engineers and I would love to hear from you on suggestions. I would love to hear from all of you on this design. I haven't figured out my landing gear yet. Winter is coming and I''ll have more time to draw up the details for fittings. I've built many model airplanes but never designed one myself. Please leave comments, good or bad. The only way to learn is to take one step forward and three steps backwards and fall down....
 

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snaildrake

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Mar 19, 2010
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247
Location
Albuquerque, NM USA
Hi Steve-
I admire anyone with the chutzpah to take on doing their own design, and I love biplanes. Could you give us some narrative on what you have: mission, key dimensions, powerplant, any interesting elements like controls surfaces, safety features, or other flight systems? I bet you'd get more specific feedback if you 'splained the design too. Cheers, Dan
 

steve-lima

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May 28, 2006
Messages
16
Location
lake Station indiana
Wing span is 16'. Wings are 36" wide. fuselage is 22" wide. I have not yet figured out the landing gear, wing curve is either going to be Clark Y or U.S.A. 27, unless someone has a better idea. Wing spars are going to be box style made of douglas fur covered with 1/8" plywood. The longerons are 3/4" x 3/4" dougles fur or white pine, depending on avalibility. The Briggs engine will have an alumium fly wheel and it will be bored 30 over to up the horse power. Should be around 20 to 25 horse power when finished.
 

PTAirco

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Sep 20, 2003
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3,519
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Corona CA
Personally I think 20-25 hp is very marginal for a draggy biplane like this. I love biplane designs and have filled endless trashcans with designs that never came to the building stage, including something similar to your idea. It looks neat, but I would recommend more power. You're better off buying a used Rotax 503 or something similar and have twice the power; I guarantee that 25 hp will result in disappointment. You can find used 503's for around $1000 easily and they are about as proven as any 2-stroke and at least were designed to swing a prop. I would take the know reliability of this engine and 50hp any day over the perceived reliability of a 4-stroke industrial engine.

Oh, and: More aileron area!

My 2 cents worth.
 

Dan Thomas

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Sep 17, 2008
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5,248
Compare your design to the Murphy Renegade and the Baby Great Lakes. Similar sizes, need more power than what you propose. Biplanes are draggy and have poor span loading.

Dan
 

taildragger

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Joined
Feb 10, 2007
Messages
18
Location
UK
Wing span is 16'. Wings are 36" wide. fuselage is 22" wide. I have not yet figured out the landing gear, wing curve is either going to be Clark Y or U.S.A. 27, unless someone has a better idea. Wing spars are going to be box style made of douglas fur covered with 1/8" plywood. The longerons are 3/4" x 3/4" dougles fur or white pine, depending on avalibility. The Briggs engine will have an alumium fly wheel and it will be bored 30 over to up the horse power. Should be around 20 to 25 horse power when finished.
Look nice photos about FP-404 http://k2.kirtland.edu/~shingleb/winfield/Tom_Riley%27s_Fisher_FP404/

Buy plans for Fisher FP-404 ($400:ermm: )

[video=youtube;Hx_tdcSM7Ek]http://www.youtube.com/watch?v=Hx_tdcSM7Ek[/video]
 
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fly2kads

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Jan 2, 2010
Messages
1,574
Location
Justin, TX
I'm jealous of the Charger. I hear that they are a bit more work than most to build, but that their flying qualities are fantastic. I hope you stay with it, even if you have to move more slowly than you would like.

I like the beginnings of your mini-bipe. I like the lines. I guess you've gotten the message about the power required, though. ;) One thing that jumps out at me is the relatively tiny vertical fin area. Looks like it's there as a way to hinge the rudder rather than a way to provide any lateral stability.

I was curious about your upper wing. Is there going to be a straight center section to which the swept main panels will be attached? Or will the panels be built as drawn, joined at the fuselage center line?

It is hard to beat those old airfoil sections for this kind of application. Between the two of them, the Clark Y may be the easier to build, but not by a whole lot. Aside from that, I think you'll just have to look at their properties and decide which one is a better match.
 

TFF

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Apr 28, 2010
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12,603
Location
Memphis, TN
I wish I had a set of Charger plans my self; it is one of the best looking experimental biplanes.
I think you are going to need 50-60 hp for something that size which is about what the 404 uses. If you are able to do the engine work on the B&S, you can do it to a VW and have enough to get out of ground effect. Used Rotax would be the easiest. Looks promising.
 

Joe Fisher

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Feb 10, 2007
Messages
1,379
Location
Galesburg, KS South east Kansas
I am afraid the weight is going to get away from you real fast. I bought a set of Zipster plans just to look at them. It is almost exactly the same size as yours. They recommend a Rotex 277 engine empty weight 249 gross 550. The weight reductions in construction to my eye are extreme.
 
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