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Dragon Lady Down

Posted: Sat Apr 29, 2017 6:45 am
by D5CAV
USAF released accident report on fatal TU-2 Crash at Beale AFB last year

https://www.stripes.com/air-force-relea ... QQy5fnyvZ4

Comments Here: http://aviationweek.com/military-traine ... ash?page=1

Re: Dragon Lady Down

Posted: Thu May 04, 2017 4:05 am
by D5CAV
I've got an acquaintance who pilots U2s out of Beale. I haven't seen him recently to ask him about this incident.

About a year ago, we were talking about the challenges of flying the U2. He casually mentioned that the U2 stall speed was a little over 400 knots at cruise altitude. That got my attention!

I asked "I thought the U2 max speed was a little over 400 knots."

He said, "Yes, the difference between max speed and stall speed is under 20 knots at cruise altitude."

I asked, "How to you manage that flight envelope?"

He said "very carefully!"

There's a reason U2 is called "The Dragon Lady"!

Re: Dragon Lady Down

Posted: Thu May 04, 2017 6:26 am
by Jericho941
Yep. At that altitude the speed of sound is so slow you actually risk going transonic if you go too fast, which would tear the aircraft apart. It's also so thin that your stall speed is incredibly fast. The U-2 is not a forgiving aircraft.

Re: Dragon Lady Down

Posted: Thu May 04, 2017 6:44 am
by Netpackrat

Re: Dragon Lady Down

Posted: Thu May 04, 2017 10:25 am
by Jericho941
When the airplane exceeds its critical Mach number (such as during stall prevention or recovery), then drag increases or Mach tuck occurs, which can cause the aircraft to upset, lose control, and lose altitude. In either case, as the airplane falls, it could gain speed and then structural failure could occur, typically due to excessive g forces during the pullout phase of the recovery.
A bit less spectacular than the way it was explained to me, heh.

Re: Dragon Lady Down

Posted: Thu May 04, 2017 6:29 pm
by Windy Wilson
Jericho941 wrote:
When the airplane exceeds its critical Mach number (such as during stall prevention or recovery), then drag increases or Mach tuck occurs, which can cause the aircraft to upset, lose control, and lose altitude. In either case, as the airplane falls, it could gain speed and then structural failure could occur, typically due to excessive g forces during the pullout phase of the recovery.
A bit less spectacular than the way it was explained to me, heh.
This must be from the same editorial board that came up with "hard start" as a euphemism for an explosion on the launch pad in rocketry.

Re: Dragon Lady Down

Posted: Thu May 04, 2017 8:34 pm
by Netpackrat
Same people who coined the phrase, "controlled flight into terrain" I think.

Re: Dragon Lady Down

Posted: Fri May 05, 2017 8:29 pm
by Mike OTDP
RQ-4s are the same way. Not much margin between stall and critical Mach. It takes time to back down from high altitude to the point where you can really start descending.