Scotland Helicopter Crash

[anonymous-user]

The "radar tapes" are availiable for the crash, and in fact, have already been analysed by the AAIB. They know exactly how fast the helicopter "fell" already!

[anonymous-user]

In other helicopter news, it looks like David Richards of Prodrive fame has had another slight upset with a chopper (knocked the tail rotor off on a tree during a night landing.......)

[TheSnitch]

CrutyRammers said:

TheSnitch said:

Eyewitnesses describe the helicopter dropping like a stone. That does not sound consistent with a ''feather-light'' touchdown. Nor does the fact that the rotors were not moving at the time of collision.

Eyewitnesses said that Charles de Menezes was wearing a heavy coat, a bag with wires comming out of it, and jumped over the barriers. So not always (ever?) reliable.

Not when the 'eyewitnesses' go on to shoot him, no.

You seem to be missing the point.
Some things are known - the rotors were not moving, for example.
Some things are not known - the cause of the accident, for example.

I fail to see how hypothesizing about the strength of the roof in order to develop a secondary hypothesis about the speed of the craft on impact really helps to determine the cause of the accident. Unless one is able to hypothesize as to the cause of the accident based on the speed on impact which to me in my ''I'm not an air accident investigator'' ignorance seems unlikely.

So it seems to me that dismissing eyewitness accounts because of their unreliability in order to substitute an unreliable, untested and unprovable hypothesis about the strength or otherwise of a 200 year old roof which started life as a ceiling is scarcely ideal.

[TheSnitch]

alfaman said:

smegmore said:

Yes I understand that but my point was how could they calculate the structural integrity of a building of that age?

If the roof has steel members - would be feasible to estimate the K.E absorbed by roof deformation - but would likely give a broad range / estimate .

would be rather tricky if wooden as not a plastic material like steel.

It was wooden and did not, of course, start life as a roof at all.

[smegmore]

TheSnitch said:

It was wooden and did not, of course, start life as a roof at all.

Ah, yes. The upper storey of the building was removed some time ago, was it not? I wonder what further work was carried out as the first floor would then have become the external roof.

All moot I think.

[TheSnitch]

smegmore said:

TheSnitch said:

It was wooden and did not, of course, start life as a roof at all.

Ah, yes. The upper storey of the building was removed some time ago, was it not? I wonder what further work was carried out as the first floor would then have become the external roof.

All moot I think.

The remaining Glasgow tenement buildings are a thing of beauty, although I should imagine they were probably pretty grim back in the day. I think they were usually four storeys high, and to me they have always looked very solidly built things - many of those that remain are of red sandstone construction. It didn't look to me as if much had been done to the roof of the Clutha other than to felt it and make it watertight. It also looked to me that because of that, and the nature of it's wooden structure, the roof had absorbed a lot of the energy of the crash before it collapsed, rather than 'punching' straight through, if that makes any sense?

[ninja-lewis]

TheSnitch said:

The remaining Glasgow tenement buildings are a thing of beauty, although I should imagine they were probably pretty grim back in the day. I think they were usually four storeys high, and to me they have always looked very solidly built things - many of those that remain are of red sandstone construction. It didn't look to me as if much had been done to the roof of the Clutha other than to felt it and make it watertight. It also looked to me that because of that, and the nature of it's wooden structure, the roof had absorbed a lot of the energy of the crash before it collapsed, rather than 'punching' straight through, if that makes any sense?

It was reported at the time that there were in fact three 'roofs'. The original first floor floor with substantial beams, extensive soundproofing and then a further weatherproof roof on top.

[TheSnitch]

ninja-lewis said:

TheSnitch said:

The remaining Glasgow tenement buildings are a thing of beauty, although I should imagine they were probably pretty grim back in the day. I think they were usually four storeys high, and to me they have always looked very solidly built things - many of those that remain are of red sandstone construction. It didn't look to me as if much had been done to the roof of the Clutha other than to felt it and make it watertight. It also looked to me that because of that, and the nature of it's wooden structure, the roof had absorbed a lot of the energy of the crash before it collapsed, rather than 'punching' straight through, if that makes any sense?

It was reported at the time that there were in fact three 'roofs'. The original first floor floor with substantial beams, extensive soundproofing and then a further weatherproof roof on top.

Interesting, thanks for that. The roof timbers certainly did look very hefty

[smegmore]

ninja-lewis said:

TheSnitch said:

The remaining Glasgow tenement buildings are a thing of beauty, although I should imagine they were probably pretty grim back in the day. I think they were usually four storeys high, and to me they have always looked very solidly built things - many of those that remain are of red sandstone construction. It didn't look to me as if much had been done to the roof of the Clutha other than to felt it and make it watertight. It also looked to me that because of that, and the nature of it's wooden structure, the roof had absorbed a lot of the energy of the crash before it collapsed, rather than 'punching' straight through, if that makes any sense?

It was reported at the time that there were in fact three 'roofs'. The original first floor floor with substantial beams, extensive soundproofing and then a further weatherproof roof on top.

Thanks for the clarification, interesting stuff.

[anonymous-user]

Max_Torque said:

The "radar tapes" are availiable for the crash, and in fact, have already been analysed by the AAIB. They know exactly how fast the helicopter "fell" already!

Hmmm........even with Mode Charlie working would the data rate be sufficient to determine an accurate rate of descent right up to the moment of impact? Will be interesting to see what they come up with and I guess it would help to know if the roof was caved in more by the weight of the aircraft settling on it (admittedly unlikely) or by sheer kinetic energy of the descent.
The "dropping like a stone" thing is probably every investigator's nightmare as anything other than straight and level flight will be described thus by Joe Public.
I'm also beginning to wonder if this wasn't an intricate combination of failures (of the million-to-one variety).
Some kind of engine problem, combined with an otherwise unrelated clutch issue that meant the shut-down engine dragged the Nr down with it. Or something like that.

Edited by anonymous-user on Wednesday 11th December 19:13

[Kinky]

Off-topic mode=ON

Trollesque post and subsequent responses made late this afternoon have been removed from thread and subsequent action taken.

And before the person concerned starts stating freedom of speech crap ... save it for elsewhere. Not interested and don't care.

Off-topic mode=OFF

[anonymous-user]

Kinky said:

Trollesque post and subsequent responses made late this afternoon have been removed from thread and subsequent action taken.

And before the person concerned starts stating freedom of speech crap ... save it for elsewhere. Not interested and don't care.

[TheSnitch]

Kinky said:

Trollesque post and subsequent responses made late this afternoon have been removed from thread and subsequent action taken.

And before the person concerned starts stating freedom of speech crap ... save it for elsewhere. Not interested and don't care.

[munroman]

Back to the strength of the roof structure, from a friend of one of the injured, the part of the bar they were at ended up in the basement, so as well as 3 layers of roof being damaged, the impact also punched the bar structure through the ground floor.

[GG89]

munroman said:

Back to the strength of the roof structure, from a friend of one of the injured, the part of the bar they were at ended up in the basement, so as well as 3 layers of roof being damaged, the impact also punched the bar structure through the ground floor.

3 tonnes of helicopter falling from the sky will do that.

[anonymous-user]

munroman said:

Back to the strength of the roof structure, from a friend of one of the injured, the part of the bar they were at ended up in the basement, so as well as 3 layers of roof being damaged, the impact also punched the bar structure through the ground floor.

Wasn't aware of that. Thanks for sharing. Guess that dismisses the idea of a heavy landing on the roof

[Super Slo Mo]

Crossflow Kid said:

I'm also beginning to wonder if this wasn't an intricate combination of failures (of the million-to-one variety).
Some kind of engine problem, combined with an otherwise unrelated clutch issue that meant the shut-down engine dragged the Nr down with it. Or something like that.

I'm thinking along the same lines, million to one chance.

That's if it has a clutch, I'm not sure all helicopters do. The engines have very little 'drag', unlike a piston engine, so if they flameout, they wouldn't force the rotors to stop quickly anyway. Of course, if something went catastrophically wrong with an engine and it somehow seized solid (I guess something would have to break for this to happen), then maybe it could, although there must be a built in fail safe for this eventuality.
I mean, for instance, a helicopter gearbox can run without oil for a certain amount of time, and is designed such that the pilot should be able to get on the ground before it locks solid.

[98elise]

Super Slo Mo said:

Crossflow Kid said:

I'm also beginning to wonder if this wasn't an intricate combination of failures (of the million-to-one variety).
Some kind of engine problem, combined with an otherwise unrelated clutch issue that meant the shut-down engine dragged the Nr down with it. Or something like that.

I'm thinking along the same lines, million to one chance.

That's if it has a clutch, I'm not sure all helicopters do. The engines have very little 'drag', unlike a piston engine, so if they flameout, they wouldn't force the rotors to stop quickly anyway. Of course, if something went catastrophically wrong with an engine and it somehow seized solid (I guess something would have to break for this to happen), then maybe it could, although there must be a built in fail safe for this eventuality.
I mean, for instance, a helicopter gearbox can run without oil for a certain amount of time, and is designed such that the pilot should be able to get on the ground before it locks solid.

Gas turbine engines are not conected to the rotors so there will be zero drag from the engine. The power turbine is on a seperate shaft.

[Super Slo Mo]

It is indeed (not connected that is), I just did a bit of retrospective Googling.

[anonymous-user]

98elise said:

Super Slo Mo said:

Crossflow Kid said:

I'm also beginning to wonder if this wasn't an intricate combination of failures (of the million-to-one variety).
Some kind of engine problem, combined with an otherwise unrelated clutch issue that meant the shut-down engine dragged the Nr down with it. Or something like that.

I'm thinking along the same lines, million to one chance.

That's if it has a clutch, I'm not sure all helicopters do. The engines have very little 'drag', unlike a piston engine, so if they flameout, they wouldn't force the rotors to stop quickly anyway. Of course, if something went catastrophically wrong with an engine and it somehow seized solid (I guess something would have to break for this to happen), then maybe it could, although there must be a built in fail safe for this eventuality.
I mean, for instance, a helicopter gearbox can run without oil for a certain amount of time, and is designed such that the pilot should be able to get on the ground before it locks solid.

Gas turbine engines are not conected to the rotors so there will be zero drag from the engine. The power turbine is on a seperate shaft.

Yep, was aware of that and probably wasn't clear. I meant something going pear-shaped, possibly power turbine related or not (bearing failure?) and the sprag clutch not disengaging fully/correctly, so although the dragging turbine might not stop the head it might slow it enough to bugger up the numbers for an autorotation.
The number 2 engine and drive train have been assessed as still capable of driving the head.....nothing on the number 1 side yet as it was damaged/disconnected during the crash.
Bit of a long shot I know......