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Old 01-10-2021, 11:09 AM   #607 (permalink)
kach22i
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Quote:
Originally Posted by Bicycle Bob View Post
What matters is the angle of attack.
I agree that the angle of attack is of paramount concern.

Considering that we (I) have not seen such large dive planes on a Baja style racer before in competition I'm going to take a "wait and see" position on their effectiveness.

Thinking about the classic blow over at speed verses getting airborne via hump or ramp, we need to admit that these are two different, or we need to lump them into the same bed.

1. Classic blow over can be caused by a crest in the pavement or in some cases another vehicle disrupting it's ground effects. Either way, once a little air gets under, a lot of air wants to follow and rapidly.

2. Baja jump is just that a jump that follows an artillery type trajectory based on vector, mass and velocity - not so much aerodynamics. In a Baja racer jumps are at lower speeds (let's say 1/2) than a LeMans racer, and therefore lower aerodynamic forces/concerns.

#1 is a frisbee.

#2 is a cannon ball.

Now to bring this back home to my original explanation, examination and defense of prior comment about looking at vertical acceleration as a separate force being impended by the horizontal surface area of canard - dive plane.

This comment failed to mention forward motion that creates lift at positive angles of attack (post #605 second paragraph) because it was meant to say that angle would not be achieved to begin with and is a preventive measure not a countermeasure.

Indeed once a positive angle of attack on the flipper like dive planes is achieved there will me more not less lift.

Keep in mind this lift condition exists under the car body as well at positive angles, especially with it's flat floor plan of thick aluminum flying it like a kite over every jump.

There are preconditions, conditions, and post conditions for every airborne incident. Certainly thinking in time frames in lieu of static conditions is out of our normal discussions, usually we get as far a buffeting and call it a day.

This has been an enjoyable brain twister for me, and will certainly be eager to read a more expert analysis than what little I have been able to offer.
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Last edited by kach22i; 01-10-2021 at 11:28 AM..
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