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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Originally Posted by mark houghton View Post
OK, one more comment before I stop and just listed for awhile.
The stalling MP, when it's near the bottom of it's range, probably has to do with increased air velocities flowing over the edges of the plate....because the "cone" gets progressively wider, opening up more air space between it and the plate. Thus, greater air velocity across the top of the plate creates a low pressure zone above the plate and higher pressures below...causing lift and "stall". It's basic aerodynamics, such as the curvature of a wing and the pressure differential top-to-bottom that causes lift.

So, attaching some sort of "airfoil" on top of the MP may not have much value unless it were able to follow the tapered contour of the cone as the MP moves downward. It may be worth a try, but we need an engineer type dude to do the math. The bottom line: It sounds like changing the pin location (and thus the fulcrum point of the arm) is probably the better option. But then that arm will move easier, and you would have to retune all control pressures accordingly.

For what it's worth....I've got to visualize the physics of how things work, before I can strategize how to modify.
Look back at the forces in the factory digram above. The metering plate in the cone is basically a big valve. The more air flow or pressure through it the more it opens the vavle. At some point the valve goes past its intened range and spills over. That is when we stall.

All we are doing it keeping the mass up in the cone area so the air pressure will keep pushing it open.

It is more a trial and error. What would be interesting is to develop a way to make the windage adjustable.

With the increased windage may come quicker advancement of the MP at first, this would be countered by makeing the MP smaller in diamiter. That is what they did with the aftermarket above. It is taller and smaller in dianiter.

How about a wedge like this. It could even then be turned to effect the rate of advancment some with out having to redo the control pressures?

Old 03-06-2009, 01:01 PM
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