Becca Posted November 21, 2011 Report Posted November 21, 2011 Well, this one actually had another Mooney 201 racing so I had competition! Thank you Walter! (I am not sure if he is actually on Mooney Space, but we met him at MAPA). I broke my record again with 186.26 mph. This is the first race I did where the wind was whipping, my ground speed varied between 130 kts - 185 kts depending on the leg. I am pretty sure this resulted in some losses (even uncalculable ones like those from the crab angles during the crosswind legs), so I think this time was a little slower than it could have been. The biggest gain from the prior 184 was jetdriven-adjusted mag timing (it was set at 20, but the spec for our plane is 25), we've noticed a measurable improvement in climb performance with this adjustment as well. I am not sure there's much more speed to be eeked out of the plane - getting the gear doors rigged right is probably the next biggest. After that, I think any more gains will be in the tenths of mph. Other differences in this race's configuration - we didn't have sand bags to shift the CG aft, but we did have a backseat passenger. Byron was my copilot this time, and I can't emphasize enough the importance of splitting and knowing your various responsibilities. Byron was (for good reason) a little fixated on my pilotage around the turns, however, this resulted in missed radio calls. Since being spotted on a turn (coupled with the radio call) is required in order to qualify for the race, this could've been a critical error. Which brings up my last thought on the turns. I've done a lot of geometry-style math trying to figure out the optimal spot before a turn and the bank angle to use in the turn - and even how much altitude loss to allow in the turn (so you don't get speed loss from the g's of a steep turn) - but I am still not quite sure I've found the optimal point. It seems to me in this case a Mooney is very different than say, a cessna, which seems to be able to pivot around its wing tip in a steep turn. Any thoughts? http://www.sportairrace.org/id453.html I'll post a couple pictures when I get them...
xftrplt Posted November 24, 2011 Report Posted November 24, 2011 Which brings up my last thought on the turns. I've done a lot of geometry-style math trying to figure out the optimal spot before a turn and the bank angle to use in the turn - and even how much altitude loss to allow in the turn (so you don't get speed loss from the g's of a steep turn) - but I am still not quite sure I've found the optimal point. It seems to me in this case a Mooney is very different than say, a cessna, which seems to be able to pivot around its wing tip in a steep turn. Any thoughts? I'm sure a lot of thought has gone into planning the turns, but I'll dare add a thought to two. The aim is not to preserve a/s in the turn, rather it's about minimizing energy loss while maximizing turn rate. Assuming you're limited to 3G's, I'd calculate the minimum a/s that gives you that loading. (Your 3G corner velocity.) Here's a "back of the envelope" approach (sitting in front of the fire pecking on an iPad) that I'm sure you can refine: If 1G L/Dmax is Vx, say, 80kias, at what a/s will that AOA produce 3Gs? (Your 3G Corner Velocity) Since G-available increases with V^2; and the square root of 3 is 1.73; therefore 1.73 x 80kts = 138kts and that gives you 3G's at that your L/Dmax AOA. So, I'd pull 3g's, let the a/s bleed to 140kts, then descent to maintain 140. After the turn, descend to regain cruise. Just my 0.00002 AMU. PS: Actually, the 3G Corner Velocity is 1.73 x Power-on Vs, but I figure if looking for energy efficiency with a thrust-limited aircraft, 1.73 x the 1G L/D speed makes more sense.
jetdriven Posted November 24, 2011 Report Posted November 24, 2011 Interesting info, Dick. She actually limited the G to 2 or less in turns because the M20J loses speed when you load it up with G. Actually, over 1.5 G she would let the nose fall and descend in order to preserve airspeed. That costs altitude, and there is a tradeoff somewhere. A 60 degree bank has half the radius of a 45 degree bank, so less miles flown with a steeper bank.
Hank Posted December 8, 2011 Report Posted December 8, 2011 Becca-- Here's a female racer asking for advice. For some reason, I thought you might have some to share. :-) http://forums.aopa.org/showthread.php?t=78241 Even if she IS in a slow, draggy Brand C . . .
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