Aircraft Crash At Shoreham Air Show

Vanity | 8-21-15 | Self

[Spktyr]

Just been informed by a friend attending the Shoreham Air Show in the United Kingdom that a Hawker Hunter has crashed, possibly onto the nearby main road. No chutes observed. No other details.

[zot]

Maybe he was too low at the top of the loop. There is no wing rock or flutter in a high-speed stall, just loss of lift and a high sink rate. He was nose-high when he hit the ground.

[Hulka]

Yes, nose high. Sad.

Been there myself, nose up, flyable airspeed, sink rate none-the-less. . .but not stalled. . .barely missed the ground, kicking up dust-devils when the sunk rate stopped and I flew up ad away. . .

Still have no idea what you mean by ‘high speed stall?”

A stall among aviators means something specific, and certainly not what this pilot was experiencing. He was not stalled.

Cheers,

[zot]

nose up, flyable airspeed, sink rate none-the-less = loss of lift due to pulling G’s at high angle of attack = high speed stall. Happened to a Thunderbird pilot during an airshow at Mountain Home AFB in 2003. He successfully ejected about one second before impact. Here is a link:
http://www.bing.com/search?q=Thunderbird+Crash+Mountain+Home+Idaho&FORM=R5FD6

[Hulka]

Again, not a stall, and the T-Bird pilot, a friend of mine, misjudged his altitude at the top of the loop. . .mistakes do happen.

Stall, separation of smooth airflow over the wing, loss of lift, meaning no lift generated because of disrupted airflow. The Hunter and the T-Bird did not stall. They were flying. An aircraft that is stalled is not flying.

Nice short explanation here: http://www.allstar.fiu.edu/aero/flight55.htm

And a very short vid (by a friend of mine): https://www.youtube.com/watch?v=5wIq75_BzOQ

Cheers.

[zot]

Terminology. In the head-on photo just before impact, you can see the condensation from separation of smooth airflow over the wing. That separation causes a loss of lift so the aircraft mushes.

[Ronald_Magnus]

Witnesses approaching the crash scene.

https://www.youtube.com/watch?v=MmIc_nFPp2Y

[Ronald_Magnus]

It appears the canopy is coming open on the jet but no ejection. Pilot evidently stayed with the plane. It's amazing that he survived.

[GreyFriar]

Thank you for the update.

[Hulka]

In the vid it is condensation, not a stall, like what you see turning under hi-G. F-16 has software that prohibits exceeding my G-limits. (Must be flying to exceed max G. . .unless you are crashing. . . Sudden impact with the ground thing).

[Hulka]

Tell me, how many hours do you have? Type of aircraft? Ratings?
Thanks.

[zot]

OK, you got me. I’m not a pilot. 3,000+ hours. B-47. Master Navigator. 15 years in R&D. My use of the term “high speed stall” was from conversations with flight test pilots. As they described it, it wasn’t a complete stall, but a loss of lift due to high angle of attack and induced drag. They also used the term “mushing” for nose-up loss of altitude during pull-out from a dive. I remember it was a problem in the F-105.

[noiseman]

Don't worry about them, you're correct. It's actually called an "accelerated stall", and every flight student learns about it. The term refers to a stall caused by an abrupt pitch change that causes the wing to exceed its critical angle of attack, even though the aircraft is flying well above stall speed. An aircraft can stall at any speed if the critical angle of attack is exceeded.

Anyone with any knowledge of aerodynamics should know this. It's very basic. That said, I don't know if this is what happened in this case as I have not viewed the video yet.

[noiseman]

OK, now I've watched the video. Zot is absolutely correct. He was definitely stalled when he hit the ground, though it is difficult to tell for sure if that was what caused the accident or if he stalled it right at the end as he instinctively tried to avoid the oncoming ground. It was very clear, though, that as he approached the ground the aircraft was nearly level yet his velocity vector was obviously downward. That would mean that at least toward the end, if not earlier, the relative wind was coming from below and striking the lower surface of the wing at a sharp angle. That will definitely cause a stall.

I also noticed his left wing dipped right before impact which could have been due to the aircraft beginning a spin (which can only happen if the wing is stalled first). It's not entirely clear, though. The pilot also may have applied sudden left stick as he saw obstacles approaching.

[Winniesboy]

It may be relevant that conditions at the time were exceptionally humid - a ‘Spanish Plume’ of hot, very unstable air from the south.

[Hulka]

If you are referring to the F-16 T-Bird incident, we was not stalled. He was pulling max G but did not have the altitude to pull it off/out.

Strickland is a good guy, just screwed up. . .all it takes in once. . .

If you are referring to the Hinter. . .didn't see anything that would involve a stall of any type.

[Hulka]

I get it.

I see where you are coming from now. Those that have not flown and have no clue why an aircraft flies, one must keep the terms basic, as in stall, meaning separation of airflow from the wing equals loss of lift. Accelerated stall is the same thing, but associated with abrupt change in the relative wind to the airfoil, can happen at any speed, and the abrupt change separates the airflow but well above “normal” straight and level 1-G slow speed flight.

The Thud. . .hmmmm. . . .just how OLD are you?

Hah.

[zot]

I am 81 years old. I started flying at age 16 in a J-3 Cub and was for awhile the youngest pilot in the Arkansas Civil Air Patrol. AFROTC commission in 1955, took the eye test seven times, read 20/30 every time, and thus became a navigator. Active duty USAF 1955-1985. I knew about the “mushing” problem with the F-105 because it was discussed when I was a research director in Air Force Systems Command.

[Hulka]

Well done. Excellent career. . I was CAP, too.

Learned to fly at age 17 with them.

[zot]

Thank you. It was a good career. I enjoyed it.

[noiseman]

Sorry, I guess I wasn't clear: I was referring to the Hawker Hunter accident. To me it looked pretty likely that he was stalled, at least right before he impacted. The aircraft was level or even a bit nose high at that point but descending rapidly, and there was a possible stall-related wing drop as well. With the big caveat that the camera perspective from the rear of the aircraft makes it difficult to judge forward motion, the downward trajectory combined with his level or even nose-high attitude could have resulted in him exceeding the wings's critical angle of attack and stalling.

To me it looked like he mushed into the ground either partially or fully stalled, and the last second wing drop adds to that impression as it may have indicated an incipient spin. I suspect he didn't have the altitude to complete the loop and upon pulling back to avoid the ground he stalled and crashed. What is unknown is whether, even if he had kept the wing flying by pulling out more gradually, he would have had the room to avoid the ground. It doesn't appear that he would have made it either way, though the video unfortunately doesn't show the aircraft at the critical moment in the pull-out.