rotax618
Well-Known Member
Doesn’t the application of a Cosandey flap have the same effect as lowering the incidence of the rear wing, it certainly is far simpler to implement.
Yes it does, but it is subtractive, and does nothing to address the loss of lift at takeoff and landing.Doesn’t the application of a Cosandey flap have the same effect as lowering the incidence of the rear wing, it certainly is far simpler to implement.
As long as a Flea flies within its self-imposed speed limits, there is no danger of a nose over. Exceed this speed limitation and all Fleas experience a dropping of the nose. Get into a strong dive (in excess of 15 degrees) and the results will be hairy, because full back on the front wing is only the differential between 12 degrees and the set angle of the rear wing.Show me an example of any nose over in the last 10 years
Your stipulation of a "wing gap more than 10 inches" is meaningless (please excuse my bluntness, I'm not trying to be provocative - just trying to be clear). The placement of the rear wing has nothing to do with an arbitrary wing gap, and everything to do with the airflow it encounters. In the screenshot below, overlapping wings would make no difference at all. If this is your major objection, then (with all due respect) you've been wrong for over a year on this matter., and with the wing gap more than 10 in. It just wont happen if you have sufficiant pitch authority, as I have said for about a year to you. Spread the wings a little and fly.
Overlapped wings may nose over as the lift center moves past the CG.
A propos wing loading: When I open the file "Design Paper spreadsheet calculations" via Technical resources - The Backyard Builder's ForumYour rear wing will fly at about 3-4 AOA. Less if you spread the wings more. Mine was about 2 AOA as the wing spread was further.
DO you believe that adding rear wing AOA will increase the rear wing loading? The only way to change the loading is to move the CG.
Hi,Question: Would using a symmetrical or mostly symmetrical airfoil on the rear wing set at a positive AOA be a viable fix for the rear wing making too much lift at high speeds?
Then if the tail lifts more than it should, the airfoil starts producing less lift as it becomes parallel to the airflow.
Hi,So the issue with the pivoting wings on the fleabike was because of the spacing?
Since a symmetrical airfoil needs positive AOA to create lift, the amount of lift it creates decreases as the plane starts to nose down. It won't ever raise the tail enough to be completely parallel to the airflow because the tail still has to support weight. There won't be more than a degree or two of pitch change for the fuselage.Hi,
I don't follow. If the rear wing (whatever the airfoil) is set to a fixed incidence, by the time the rear wing is parallel to the airflow, the plane is already nose-down by the rear wing incidence set.
Duncan
It would be interesting to plot the lift against airspeed and AoA.Since a symmetrical airfoil needs positive AOA to create lift, the amount of lift it creates decreases as the plane starts to nose down. It won't ever raise the tail enough to be completely parallel to the airflow because the tail still has to support weight. There won't be more than a degree or two of pitch change for the fuselage.
If the plane is nosing over where do you think think the airflow is coming from? And as the wing now has to support less weight it gets even better at doing its job.It won't ever raise the tail enough to be completely parallel to the airflow because the tail still has to support weight.