Quote:
Originally Posted by Teri_TX
Hi P-Hack,
Are you suggesting active counter measures like "fly by wire". I had thought of this in a moment of madness. If we had military or NASA budgets, that might be a possible solution. Think of the F-117. Besides, do we really want a bunch of code monkeys designing active control systems for our streamliners? Fighter jocks volunteer and get paid to risk their lives on monkey code. Unfortunately, if you fly on a modern airliner, you're a potential victim of bad code. I haven't flown since before 11 Sept 2001 and don't plan to. Apologies in advance to the real code monkeys among the readers.
Once, when I was looking at Vetter's long tail, a trim tab came to mind but he routinely rides through areas of rapidly shifting side wind directions, a worst case situation. A trim tab may be an option for some conditions but be aware of situation changes!
I have tried to think of how an active spoiler system could be implemented but nothing remotely simple comes to mind. Stall strips are the simplest solution I presently know of. Remember, K.I.S.S. (Keep It Simple, Stupid)
Passive automatic means are best for reliability in the real world.
-- Teri
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K.I.S.S., definitely.
I'm exploring wing stalling for my design, somewhat akin to what F1 does for their rear spoiler by injecting air across the underside of the "wing". It's reversed in their case, since they're trying to create downforce, but the same principle applies... stall the wing. In our case, we'd inject air on the upper side of the "wing" to stall it, since it's reversed from the F1 downforce-producing wing.
I plan on doing it by having two scoops at the front of the bike, their openings angled backward at about a 15 degree angle. They'll scoop the air into ducts that cross over to the other side of the bike and exhaust further rearward and higher. Two small radiators will sit in those ducts, heating the air and thus lowering the density, which will help to "fill the void" and stall the "wing".
Going straight, both scoops provide relatively equal amounts of air to both sides of the bike, so the forces balance out. If you're getting hit with wind from the left, the right-hand scoop would be shielded by the bodywork, and thus the left-hand scoop would be forcing more air to the right-hand side of the bike, stalling the "wing". Vice versa for wind from the right.
Because the air exhausts a bit more rearward and further up than where it's scooped in, it moves the CoP rearward and lower because that exhausted air acts as a "longer lever" to counteract the side-wind loading.
Tony Foale Designs, article on motorcycle aerodynamics.
"To reduce the degree of lean necessary, we need to generate a small side force combined with a low C of P., to give the minimum disturbing effect..."
Further, the scooped air acts to "rob" the upwind side of the "wing" of some airflow, lessening the force on the upwind side of the bike.
A side benefit is that the air being injected back into the airstream during straight-line riding should help to keep the air attached to the body, thus giving better aerodynamics.
I plan on exhausting the hot engine exhaust (and the air that's pushed through the engine compartment to cool components, which will be scooped at the front of the bike via a small venturi intake to remove the "stalled" air directly in front of the bike) at the rear center of the bike to "fill the wake" and further reduce rearward drag.