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1st scratch bipe

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1st scratch bipe

Old 03-15-2002, 01:10 AM
  #1  
RSands
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Default 1st scratch bipe

Hello out there! I'm in the design stages of building my first serious scratch build, an SE5A, WWI biplane. The target is 1/5 scale which will result in ~63" WS, and I want to power it with a 91 FS. The aircraft was "a stable gun ship" which is encouraging, but I'm a little leary of the airfoil, an RAF15, which is undercambered, and also of the positive 5 degree wing incidence. I'd really really like to keep it scale looking, and am not concerned with a bunch of non-scale aerobatics, but also want it to be a relaxing plane to fly and land. I love the undercambered appearance and really want to keep this, and the 5 incidence would be very noticeable if missing, but I'm guessing, based on the airfoil it would have some rather nasty stall characteristics, combined with a serious tendancy to climb! If I keep the airfoil, put the 5 in the bottom wing & 4 in the top, put 6 in the evevator, keeping the motor @ 0, I'm thinking it still might work. Net result would be -1 on bottom wing, -2 on the top, and -5 on the motor. I'm new to all this, so the $50,000 question is: Am I on the right track, or out to lunch? If so, what's the solution? Any and all advice appreciated!
Old 03-17-2002, 02:25 AM
  #2  
Noflyzone
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Default SE5

Hello,

WWI biplanes can be one of the most challenging of all scale subjects. All of them have very small stab areas (little downforce pressure available) Relatively low thrust to weight and short tail moments in relation to the area of the two wings. The people that designed these things did the best they could with the technology available, but sometimes the best laid plans and all.....
Anyway, In order to have a managable aircraft, it's important to discover the angle of zero lift on the airfoil before you try to second guess the original design; if you don't, you will be only guessing at how it will fly. I think you've got the right idea in trying to negate the nasty habits of the SE5. It was one of the best, but still far from a happy flier as a model...GOOD LUCK...

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