Whale Tail Strike ... 380

[P-Dawg_QX]

I'm guessing a test of the tailhook system...you know, for aircraft carrier certification.

 

[cforst513]

bet that was loud to listen to

 

[aeronautic1]

Boeing

I use to watch Boeing doing htese tests at Moses Hole (Grant County Airport) for the 747, 757 and 767. The mounted a huge oak block under the tail and drag it so at to not dammage the aircraft.

 

[billybob sblade]

Alpha is angle of attack.

Just in case someone did not know.......

 

[BD King]

The Vmu test is performed to ensure that the aircraft can still take off if it is rotated too early by the pilot. Some early types (DC-6, I think) would stop accelerating if they were rotated early, so even though you were trying to fly, it was never going to happen.
Certification standards under Part 25 require an aircraft to be able to take off at any speed above that where the elevator physically has the authority to raise the nose off the ground. The high alpha involved in the test means the tail usually scrapes along the runway before liftoff.

Basically, this is correct. If the pictures were more clear, you would see something akin a a railroad tie bolted to the arse end.

www.bdkingpress.com

 

[Rez O. Lewshun]

I am so confused. Now the A380 is (a) the whale? What about the other whale; B747....

And the Original: A-3

 

[philo beddoe]

If I had to guess, I would say that they probably do it at the forward and aft CG limit, for two reasons (which are also guesses). One, at the forward limit, the nose would likely come up later than a mid CG, and the stalling speed would be higher. Two, at the aft CG, the nose would come up right away, hindering continued acceleration very early in the takeoff roll.

Or, on second, though, I suppose they do at at a selection of weight and CG's.
Or would that be C's of G?

 

[Sam Snead]

I thought that the Vmu was the basis for other V speeds. Any engineers know?

 

[crash-proof]

I think the purpose of this test is to prove the aircraft can become airborne if over-rotated, or rotated too early. I can't remember which plane it was, but an early jet was over-rotated onto its tail and subsequently crashed because it was not able to get airborne after that event. Part of the certification of new jets is to make sure they can power out of that situation.

That was the Comet. I read that everyone walked away from that one, even though the plane went into the bushes. Pilot was fired and spent rest of life defending his name. Interesting times, the beginning of the jet era.