teamgrumman(at)YAHOO.COM Guest
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Posted: Wed Oct 06, 2010 9:57 am Post subject: Brain fart: Pics of the dye flow testing. |
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No, that's not it. I guess I didn't push send after loading the pics.
I'll try again.
First pic: Note the recirculation zone behind the PF muffler without the fairing. Lotsa drag
Second pic: This is the second version of the fairing that goes behind the muffler. This moved the turbulence to the space between the nose gear fairing and the muffler fairing.
Third pic: There have been a whole slew of tests between second pic and this one. I tried three different locations for the angle of the fairing to the airstream. Note, this version doesn't have the nose gear fairing. Removing the fairing hurt CHTs, so, I went looking for a fix without increasing drag. The NACA ducts had no affect on CHTs, BUT, they gave me a couple of knots. I think accelerating the airflow in the exit ramp reduced the difference between the cooling air speed and free stream airspeed, thereby reducing drag.
The LoPresti nose bowl (sorry AJ) uses a very large NACA duct on one side to improve cooling. This would be fine, but, the ramp is too short for it's height. This would work better if the ramp were 4 feet long for the height of the ramp. "I think" the air flow is too slow for that large of a ramp. This hurts drag.
I have an idea for a test cowling that may fix the cooling problem without hurting cooling drag. Composite Dave will start working on it after a few other projects are finished.
"Never leave well enough alone." Raymond Loewy.
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