As long as you don’t have to be ultra-precise, TAS can be calculated without OAT. There is a rule of thumb that TAS increases 2% for every 1000 ft above sea level. (yes I’m getting this out of a book, you know I’m not the, area is = pie x radius sqd, kinda guy!) However, I do know about area growing because of pie!
I’m on a search to justify my 8043 prop in the South, besides the aesthetic value of helping a plane look like a plane ought to look.
1. If Joe and I take off at the same time and he climbs at 500 fpm @ 70 mph and I climb at 1000 fpm @ 70 mph, then my TAS would be increasing over his 1% for every 1000 ft., until cruise? His angle of attack would be less. If I get to 8000 when he gets to 4000, will my 4% TAS cruise advantage get me a jump in the next 8 mins before he comes barreling by at 20 mph faster? For 8 mins I could cruise at 40 mph faster (105 mph (2600rpm) + ~5mph altitude = 110). That'd be about 5 miles ahead when reaches 8000? It would take him 15mins to catch up the 5 miles with his 20mph faster cruise prop? I don’t know if I said that right, but you see what I’m getting at. Is this flawed thinking? Should I max my climb on 3 hr trips, like the airlines?
2. This summer I didn’t experience the kind of lonnnnng takeoffs that ya’ll were describing in the hot, less dense air. Or what I was I was expecting anyway. Is my climb performance 8043 going to drop proportionally to a 7653 in heat and altitude? If I’m flying behind George to the 2004 convention out west, will I catch up and pass when he’s circling to gain altitude for going over the Rockies? Are there other variables involved?
This will probably be really lame. When the air is thinner at 10,000 ft or 110 OAT. Is there any chance since my prop grabs more air that it might not decrease in cruise performance as much as the thinner/shallower pitched props or is this all still just proportional no matter what? Wouldn’t the cruise prop lose climb capabilities at higher altitude before climb prop? I’ve jumped up to 12,000 for a few minutes, just to play around McKinley, but it was definitely loosing climb performance.
3. If I wanted to give up some climb performance for better cruise, should I just decrease the pitch to 80## something, or should I just take the 60hr prop, 60hr 8.50 tires, droop tips and everything Alaskan (V-brace) and send them to Spiro or Bruce? Then turn it into a street plane.
It hurts to even think about it, but my wife and I were discussing that when we reach retirement in 30 or 40 yrs and start flying to Conventions, will we still want the off road plane anymore?
But on the other hand, what’s 115mph compared to 100mph? No one should be flying a 170 for speed anyway. They’re made for landing within 300’ in the dark and looking good!
My wife's still eyeing that Saratoga!
