bdk wrote:
If someone can find an online resource or can post a scan of the L/D graph for that airfoil section, we can get a more precise calculation of the drag. In any case, the drag increase would still be very small.
Any anecdotal evidence from a race pilot would be appreciated.
FWIW, John Penny, the pilot of Rare Bear, wrote this a while back on another aviation forum on his opinion concerning the original question in relation to "G" loading, turn radius, optimal race course profiles, etc.:
John Penney wrote:
Your short question has several parts to the answer, some with lengthy portions.
The short answer is: it depends.
You are right that a lower aspect ratio will typically result in more energy loss anytime Gs are applied in a turn, be it in combat maneuvering or around a pylon. But reducing wing span also results in less wetted area and usually results in a lower overall drag coefficient allowing better speed during the “unloaded” portions of the racecourse. In some cases, the amount of span reduction is driven more by the geometry of the existing wing construction, available aileron hinge locations, etc., than by rigorous aerodynamic analysis.
Course design at Reno also dictates, at higher course speeds, G loading at the pylons that may otherwise not be optimal for the actual layout of the course. When coming off outer six, a more efficient line would take the higher speed racers outside the west deadline. Off of pylons one and two if a very healthy level of G is not maintained, one runs the very real risk of violating the east deadline.
The above being said, there is also a tradeoff between, flying a line that results in the lowest energy bleed that is geometrically much longer, and a much shorter, tighter course that incurs higher energy bleed when rounding the pylons. Again, the ability to strike the proper balance is sometimes constrained by the west, south, and east deadlines that define the outer limits of the racecourse. When Jimmy Doolittle broke the “250 mph barrier” at Cleveland in 1932, film clips show him flying a very high, very loose course line that allowed a minimal energy bleed. He was a magician at the controls of the “Gee-Bee”.
Another influence in energy bleed is the airfoil cross-section. The sharper radius of the leading edge of the P-51 results in a higher drag rise at the angles of attack reached in the pylon turns, as opposed to the more round profile of the Bearcat, or a Corsair. But, the coefficient of drag of the P-51 airfoil is less than those others on the straight-aways.
Energy bleed will also depend on the efficiency of the propeller design and how close the helical tip Mach is to approaching the blades’ critical Mach number.
Then there is other racecourse traffic. Because of our safety rules in the Unlimited Division, we are usually constrained to make a pass outside or above the plane being passed. The line they are choosing to fly may have an impact on the line the passing aircraft has to fly during the pass, and the subsequent geometry of the line at an upcoming pylon turn.
So, because of course constraints, at the very high race speeds approaching 500 mph, it is very difficult to avoid G levels of four and a half to five and a half at various pylons. The course constraints hinder being able to fly an “optimal” G at some of the pylons.
To answer your original question – 10 to 20 KIAS.
“Bear” Driver
Regarding the last sentence there, the question is how much airspeed loss is there associated with the turns on the Reno Race couse. The answer is 10 to 20 KIAS.
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But some guys can stay low and stay away from all that messy air and stay "smooth" 
)