angle of wing incidence
06-18-2002 | 09:29 PM
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From: morcambe na, UNITED KINGDOM
angle of wing incidence
I have an HE162 model jetplane from Century jets and am having problems with the angle of wing incidence for take-off.
Can anybody give me any info or rule of thumb to work from. The plane does not seem to want to lift and the nose is bouncing. I have ensured that the c.g. is correct but just dont know what else to do to resolve the problem.
Can anybody give me any info or rule of thumb to work from. The plane does not seem to want to lift and the nose is bouncing. I have ensured that the c.g. is correct but just dont know what else to do to resolve the problem.
06-19-2002 | 02:49 AM
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From: Pace, FL
Wing Incidence
Interesting problem. I think I'd tackle it this way. First, if you have a symmetrical airfoil, or something close to it, check to be sure the wing is about + 1/2 to +1 deg relative to the stab (which should be 0 deg relative to the fuselage centerline). Then measure the angle of wing incidence with the model sitting on a level surface, fully fueled for takeoff (I'm assuming you have some type of shock absorbing struts on the gear).
If the ground incidence angle of the wing is negative with the model fueled for takeoff, you've probably found your problem. I'd shorten the springs in the MLG struts to get the gear to compress a little more, or lengthen the nose strut to get the wing incidence to at least 0 deg. relative to the runway (parallel).
Given the high thrust line of the He-162 you'll get a nose down pitching moment under full power until the elevator becomes effective and can overcome the thrust offset and rotate the model nose up, bringing the wing to a positive angle of attack for takeoff.
If the ground incidence angle of the wing is negative it only acts to keep the model planted on the runway. The down force from the wing adds to the nose down moment from the engine pod and it takes even more speed on takeoff for the elevator to overpower this combination (if it's able to at all). I think that might be what you're seeing.
Let us know what you find out.
Tom
If the ground incidence angle of the wing is negative with the model fueled for takeoff, you've probably found your problem. I'd shorten the springs in the MLG struts to get the gear to compress a little more, or lengthen the nose strut to get the wing incidence to at least 0 deg. relative to the runway (parallel).
Given the high thrust line of the He-162 you'll get a nose down pitching moment under full power until the elevator becomes effective and can overcome the thrust offset and rotate the model nose up, bringing the wing to a positive angle of attack for takeoff.
If the ground incidence angle of the wing is negative it only acts to keep the model planted on the runway. The down force from the wing adds to the nose down moment from the engine pod and it takes even more speed on takeoff for the elevator to overpower this combination (if it's able to at all). I think that might be what you're seeing.
Let us know what you find out.
Tom
