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Aerodynamics Discuss the physics of flight revolving around the aerodynamics and design of aircraft.


Old 10-01-2002, 08:55 PM
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i have a hog bipe that i am just breaking in it has a magnum 91 4st. a 13x6 prop . my problem is when i give it full throttle it wants to climb at a steep rate (about 20 degrees) and balloon out of turns . more throttle more balloon . i thought i might have a incedence or thrust angle problem or is this normal ? in level flight at a set throttle level the plane flies beautiful.
Old 10-02-2002, 12:03 AM
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According to my "Flight Trimming" chart: To check incidence; put the plane in knife edge flight. If the model tends to veer towards the canopy, reduce the wing incidence. If it veers towards the gear, decrease the incidence. To check engine thrust angle; from straight and level flight, chop the throttle quickly. If the plane pitches nose up, decrease downthrust. If it pitches nose down, increase downthrust. If it continues on a level path for a short distance, thrust angle is OK. Hope this helps.
Old 10-02-2002, 02:35 PM
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Check the incidence with a reliable meter. On all my bipes (well over a dozen) I have had to put about 1.5 degrees less incidence in the upper wing than in the lower wing. They also all required about 3 to 5 degrees of downthrust and about 3 degrees right thrust. Just minor changes in the upper wing incidence can have a major effect on flyability.
Old 10-18-2002, 11:15 PM
Hal deBolt
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Hi jneesy,
You have a bipe that is giving you fits?
Not having all the design details only experience with other bipes
is the only offering.
Know this>I will give you a force arangement which will provide
excellent performance with any biplane arrangement.
The reason you see what you do is that the lift of the horizontal
tail is not in proportion to the wing lift except apparently at one
flight speed.
When the proportion is correct the craft will stay level over a wide
speed range and in any attitude.
It appears your wings are lifting more than the tail, proportion is
in favor of the wings.
Bipe force arrangement> Top wing +1 deg. Bottom wing 0 deg.
stabilier +3 deg. Engine neutral to line of flight.
If you try this please let me know if it helped, OK?
Good luck!

Hal deBolt [email protected]

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