Vne

[Charliesixtysix]

LAA annual Permit renewal test flights require flight at Vne - not a knot over nor a knot under... at Vne.

Doesn't bother me at 160kts in the Twister but I have a gentle word before doing this part of the flight test in the 1959 Jodel to make sure all the woodworm are holding hands tightly....

[Adrian]

In 1971 of-course the computing power wasn't there and the level of analysis wasn't there. I know nothing about the incident, but I'm inclined to believe that that FTE, if he was properly trained and supported, was just unlucky rather than stupid in any way.

Flight testing is a dangerous game - always was, always will be. Even in 1971 however, it was mature enough as a field to recognise the risks and the likelihood of errors in the flutter predictions, and plan for those.

I believe the same engineer had done flutter analysis for plenty of other aircraft. As you say, it's a bit of a black art. I'm not sure if the NTSB ever did a full report - all I could find was this: http://www.ntsb.gov/aviationquery/brief ... 1905&key=0 - although the manufacturer certainly had a lot of detailed information about the sequence of events. The pilot went on to write one of the standard text books about flight testing, and I believe he discusses the incident more there.

As for planning for the consequences, my understanding is that the loads at the moment of disintegration were extreme, and the pilot found himself outside the aircraft. Impossible to know if the engineer retained consciousness.

[Genghis the Engineer]

Not unheard of to see those sort of loads during a sudden breakup - and as I said, flight testing is a dangerous game. All involved in it know and recognise that (as do our spouses and, sadly, life insurance companies).

G

[MichaelJP59]

LAA annual Permit renewal test flights require flight at Vne - not a knot over nor a knot under... at Vne.

Doesn't bother me at 160kts in the Twister but I have a gentle word before doing this part of the flight test in the 1959 Jodel to make sure all the woodworm are holding hands tightly....

I've always thought this is a bit of an odd requirement from the LAA for the Permit renewal flight, and usually done by the owner as well, not a skilled test pilot. If the idea is to see if everything is safe at Vne, then there are two possibilities. Either it passes, and you tick the box on the Permit renewal form, or it fails, in which case hopefully you have a parachute. Shouldn't they ask for a lower percentage of Vne, to be on the safe side?

[Adrian]

Shouldn't they ask for a lower percentage of Vne, to be on the safe side?

I suspect that is what they almost always get, regardless of what is declared on the permit renewal form.

[Paul_Sengupta]

Didn't the C of A air test involve a Vne dive? It was always done on mine. So I hear anyway...I was never on board!

[Keef]

It did (doesn't any more on C of A aircraft). I did several of those in years past.

[Lefty]

Didn't the C of A air test involve a Vne dive? It was always done on mine. So I hear anyway...I was never on board!

It did. I have done several on my aircraft (as mentioned earlier in this thread).

[Cobalt]

Am I the only one who thinks of a Vne "test" as part of a C of A renewal a bit funny?

If it is a genuine "test", such as a skill test, you conduct it with the expectation to succeed but a non-negligible likelihood to fail.

• If there is any genuine concern the aircraft might not pass in less than, say, one-in-a-few-million cases, you would be crazy to fly that test.
• If, on the other hand, it is certain that the aicraft will pass, it is a pointless [albeit fun] exercise.

Surely there are better ways to ensure structural integrity of aircraft?

[SteveN]

LAA annual Permit renewal test flights require flight at Vne - not a knot over nor a knot under... at Vne.

Doesn't bother me at 160kts in the Twister but I have a gentle word before doing this part of the flight test in the 1959 Jodel to make sure all the woodworm are holding hands tightly....

I've always thought this is a bit of an odd requirement from the LAA for the Permit renewal flight, and usually done by the owner as well, not a skilled test pilot. If the idea is to see if everything is safe at Vne, then there are two possibilities. Either it passes, and you tick the box on the Permit renewal form, or it fails, in which case hopefully you have a parachute. Shouldn't they ask for a lower percentage of Vne, to be on the safe side?

Yes and it is done at MAUW too. I always thought it was a bluddy stupid thing to do and for most of our renewals we did it IAS because I didn't realise it was TAS. Perhaps that should be in big letters on the permit renewal form. The RV would get to Vne is few seconds in a shallow dive. Vne was set because of flutter on the RV-9.

I think our TB20 would get to Vne in a few seconds too. It does go down hill fast when clean.

[Paul_Sengupta]

Am I the only one who thinks of a Vne "test" as part of a C of A renewal a bit funny?

If it is a genuine "test", such as a skill test, you conduct it with the expectation to succeed but a non-negligible likelihood to fail.

• If there is any genuine concern the aircraft might not pass in less than, say, one-in-a-few-million cases, you would be crazy to fly that test.
• If, on the other hand, it is certain that the aicraft will pass, it is a pointless [albeit fun] exercise.

Surely there are better ways to ensure structural integrity of aircraft?

Yes, I've thought the same thing. What exactly is this in aid of? But I can see that perhaps as you approach Vne, things could start to happen - perhaps things start to make funny noises or vibrate or something at which point the test would be called off. If you start hearing cracking noises on a wooden aeroplane or bits of fabric start flapping on a tube and fabric one, then it would surely be a sign to stop the test and fail the aircraft! Perhaps on an aluminium aircraft some rivets may pop! Dunno.

[Flyingmac]

I've recently done a dive to VNE in a Jodel. Part of the flight test on a different prop. RPM was recorded at VNE so I suspect it was to check that said prop didn't cause an engine overspeed at VNE. It didn't. Can't say the same for my pulse though.