Comet Cover-up
Ecce Homo! Loquitur...
Please read the accident report. In particular:
(b) Criticism of de Havillands' design work
116. Dealing first with the period prior to the commencement of the scheduled passenger service on the 2nd May, 1952, the calculations made by de Havillands were criticised and it was suggested that the tests they carried out were inadequate to guard against the risk of fatigue in the cabin structure. In support of this contention particular reference was made to certain calculations included in paragraph 4 of Part 3 of the R.A.E. Report and to other calculations produced by Sir Arnold Hall in the course of his evidence. It is, however, to be observed that the primary object of de Havillands was to lay the foundation for extensive tests which they regarded as the soundest basis for the development of a project rather than to arrive at a precise assessment of the stress distribution at the corners of the cabin windows.
117. I do not think that they can justly be criticised for this approach to the problem. In arriving, at this conclusion I have been assisted by a Memorandum which has been prepared for me by my Assessors and which confirms the impression I formed from the evidence of the witnesses that de Havillands were proceeding in accordance with what was then regarded as good engineering practice. I am also satisfied that in the then state of knowledge de Havillands cannot be blamed for not making greater use of strain gauges than they actually did or for believing, that the static test that they proposed to apply would, if successful, give the necessary assurance against the risk of fatigue during the working life of the aircraft. The Memorandum to which I have referred is included as paragraphs 118 to 129 of this Report.
QUESTIONS AND ANSWERS
My answers to the questions submitted on behalf of the Attorney-General are as follows:_
Question 1
What was the cause of the accident?
Answer.
The cause of the accident was the structural failure of the pressure cabin brought about by fatigue. See para. 95.
Question 2.
If several factors caused the accident what were such factors and to what extent was each contributory?
Answer.
This does not arise.
Question 3.
Was the accident due to the act or default or negligence of any party or of any person in the employment of that party?
Answer.
The accident was not due to the wrongful act or default or to the negligence of any party or of any person in the employment of any party.
Official accident report of Comet I G-ALYP
(b) Criticism of de Havillands' design work
116. Dealing first with the period prior to the commencement of the scheduled passenger service on the 2nd May, 1952, the calculations made by de Havillands were criticised and it was suggested that the tests they carried out were inadequate to guard against the risk of fatigue in the cabin structure. In support of this contention particular reference was made to certain calculations included in paragraph 4 of Part 3 of the R.A.E. Report and to other calculations produced by Sir Arnold Hall in the course of his evidence. It is, however, to be observed that the primary object of de Havillands was to lay the foundation for extensive tests which they regarded as the soundest basis for the development of a project rather than to arrive at a precise assessment of the stress distribution at the corners of the cabin windows.
117. I do not think that they can justly be criticised for this approach to the problem. In arriving, at this conclusion I have been assisted by a Memorandum which has been prepared for me by my Assessors and which confirms the impression I formed from the evidence of the witnesses that de Havillands were proceeding in accordance with what was then regarded as good engineering practice. I am also satisfied that in the then state of knowledge de Havillands cannot be blamed for not making greater use of strain gauges than they actually did or for believing, that the static test that they proposed to apply would, if successful, give the necessary assurance against the risk of fatigue during the working life of the aircraft. The Memorandum to which I have referred is included as paragraphs 118 to 129 of this Report.
QUESTIONS AND ANSWERS
My answers to the questions submitted on behalf of the Attorney-General are as follows:_
Question 1
What was the cause of the accident?
Answer.
The cause of the accident was the structural failure of the pressure cabin brought about by fatigue. See para. 95.
Question 2.
If several factors caused the accident what were such factors and to what extent was each contributory?
Answer.
This does not arise.
Question 3.
Was the accident due to the act or default or negligence of any party or of any person in the employment of that party?
Answer.
The accident was not due to the wrongful act or default or to the negligence of any party or of any person in the employment of any party.
Official accident report of Comet I G-ALYP
Last edited by ORAC; 10th Jun 2002 at 20:07.
Join Date: Mar 2001
Location: Wet Coast
Posts: 2,335
Likes: 0
Received 0 Likes
on
0 Posts
However, it absolutely amazes me that they used square windows on a pressurised airframe. Even 50 years ago the science behind stress concentrations on corners was very well understood. Why did they do it???
Ecce Homo! Loquitur...
The ADF window:
75. By examination of the piece containing the A.D.F. windows and the adjacent pieces (see Figure 12) it was established that it was here that the first fracture of the cabin structure of Yoke Peter occurred. In general terms, it took the form of a split along the top centre of the cabin along a line approximately fore and aft passing through corners of the windows as shown in Figure 17. The direction in which the fracture spread was determined by examination of the lines of separation of the material.
75. By examination of the piece containing the A.D.F. windows and the adjacent pieces (see Figure 12) it was established that it was here that the first fracture of the cabin structure of Yoke Peter occurred. In general terms, it took the form of a split along the top centre of the cabin along a line approximately fore and aft passing through corners of the windows as shown in Figure 17. The direction in which the fracture spread was determined by examination of the lines of separation of the material.
Join Date: Aug 2001
Location: Brighton, MI, USA
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Lou Scannon wrote:
"His name was Neville Norway actually. He decided to use the name "Shute" (his mother's maiden name) so that his boss, Mr B. Wallis and his firm, Vickers, wouldn't know that their Chief Calculator on the R100 also wrote novels! He eventually became his own boss when he formed an outfit called "Airspeed".
Try reading "Slide Rule" the autobiography of an engineer."
His name was Nevil Shute Norway, from which he took his nom-de-plume.
His mother's maiden name was Mary Louisa Gadsden. The name Shute traces back to the Cornish roots of his father, Arthur Hamilton Norway.
llater,
llamas
"His name was Neville Norway actually. He decided to use the name "Shute" (his mother's maiden name) so that his boss, Mr B. Wallis and his firm, Vickers, wouldn't know that their Chief Calculator on the R100 also wrote novels! He eventually became his own boss when he formed an outfit called "Airspeed".
Try reading "Slide Rule" the autobiography of an engineer."
His name was Nevil Shute Norway, from which he took his nom-de-plume.
His mother's maiden name was Mary Louisa Gadsden. The name Shute traces back to the Cornish roots of his father, Arthur Hamilton Norway.
llater,
llamas
Join Date: Oct 2001
Location: South of the river
Posts: 55
Likes: 0
Received 0 Likes
on
0 Posts
Horrible Thing
It sould have never been built in the first place - front door on the wrong side - an absolute ground engineers nightmare.
I cannot wait till that awful thing that sits like a ghost on 136 at LGW is reduced to kitchen foil and milk bottle tops.
Sorry
I cannot wait till that awful thing that sits like a ghost on 136 at LGW is reduced to kitchen foil and milk bottle tops.
Sorry
Join Date: Mar 2001
Posts: 130
Likes: 0
Received 0 Likes
on
0 Posts
PaperTiger,
All of the types you mention with square windows attained far lower altitudes than the Comet, therefore the pressure differential was a lot lower and the stress/strain cycling a lot less. They could use square windows no problem, the Comet could very obviously not.
The British aircraft industry certainly learned a lesson from it though, going from paper thin skins on the Comet to over engineered "brick sh*thouse" designs, i.e VC10, Trident, 1-11......
All of the types you mention with square windows attained far lower altitudes than the Comet, therefore the pressure differential was a lot lower and the stress/strain cycling a lot less. They could use square windows no problem, the Comet could very obviously not.
The British aircraft industry certainly learned a lesson from it though, going from paper thin skins on the Comet to over engineered "brick sh*thouse" designs, i.e VC10, Trident, 1-11......
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
Hmmm...perhaps why these types did not sell well, elsewhere. Except "possibly" the 1-11.
However, sure took the maximum advantage of converting kerosene....into NOISE.
However, sure took the maximum advantage of converting kerosene....into NOISE.
Last edited by 411A; 12th Jun 2002 at 19:49.
VC10 and Trident sales
Actually 411A, in my view politics were the main reason for the VC10 and Trident sales figures, or lack of them.
For more info:
A Little VC10derness
Trident Domain
For more info:
A Little VC10derness
Trident Domain
Join Date: May 1999
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
Obviously, I haven't seen the programme yet - but if it concentrates on the performance issues associated with the operation of the Comet in the early days (leading up to a few particularly nasty accidents when the aircraft failed to complete the lift equation) - a good book to read is "Cone of Silence" by David Beaty.
The book is a very thinly veiled description of the early days of Comet operations and, like'No Highway', was also made into a thoroughly 'stirring' British film.
The book is a very thinly veiled description of the early days of Comet operations and, like'No Highway', was also made into a thoroughly 'stirring' British film.
Join Date: Mar 2001
Location: Wet Coast
Posts: 2,335
Likes: 0
Received 0 Likes
on
0 Posts
Quite right basil, I was offering a possible explanation why they did it, not suggesting it was a good idea. Specially since Neville (Shute) Norway had predicted just such a failure in No Highway.
The Trident and VC-10 were commercial failures because they were designed for the specific needs of two airlines (BEA, BOAC) who kept changing their requirements and otherwise d!cking about with the design.
The Trident and VC-10 were commercial failures because they were designed for the specific needs of two airlines (BEA, BOAC) who kept changing their requirements and otherwise d!cking about with the design.
Join Date: Jul 2000
Location: Kent, UK
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
I am more than a little worried about the programme tonight - the FT review in it today mentions the 'short lived Comet airliner' 1952 - early 80s? Hardly short lived!
Also it refers as one of the criticisms to "having been developed in only 3 years where 7 years is more normal for most airliners".
To compare the Comet with the B.707, development times seem little different:
Comet: Design work commenced 1946, first flight 1949, entry into service 1952
B.707 Design work commenced 1952, first flight 1954, entry into service 1958
Also it refers as one of the criticisms to "having been developed in only 3 years where 7 years is more normal for most airliners".
To compare the Comet with the B.707, development times seem little different:
Comet: Design work commenced 1946, first flight 1949, entry into service 1952
B.707 Design work commenced 1952, first flight 1954, entry into service 1958
Join Date: Oct 1999
Location: UK
Posts: 3,325
Likes: 0
Received 0 Likes
on
0 Posts
Very well done, I thought. Having Bill Gunston on the program ensured at
least some good sense and deep knowledge, as did having recollections from
pilots and engineers who were there at the time.
Just two gripes: it's all very well saying that the Americans were miles
behind, and there was plenty of time for full pressure tests etc and still
be first into the Jet Airliner business. But that's with the benefit of
hindsight, which is always 20/20.
And I find it hard to believe that a designer of RE Bishop's calibre would
allow a major design change - riveting the window surrounds instead of
'Reduxing' them - without checking what effect the drilling of hundreds of
extra holes would have on the structure.
It was also interesting to note that the prototype (the one with
single-wheel main gear) had leading edge slats, which were deleted on the
production machines. I wonder if that's why the wing leading edge on these
early Comets was wrong shaped, leading to the two 'over rotated' take off
crashes? BTW, did you note the clouds of concrete dust as the prototype took
off? The Hatfield runway was still new then - it was a post war addition.
Only broken up a couple of years ago :~(
I must also take issue with something Bill Gunston said - "they always come
unglued, DH aircraft". He was referring to the period between the end of the
war and the Comet disasters - and I can only think of the DH110 in flight
break-up at Farnborough that fits that bill. I don't think Vampires or
Venoms were prone to it (or indeed the Chippy, though that's DHC) - you have
to go back to the pre-war 'Flamingo' to find a 'weak' DH aeroplane. The
biplanes were strong, and all post-Comet DHs were as well (125, Trident,
146).
SSD
least some good sense and deep knowledge, as did having recollections from
pilots and engineers who were there at the time.
Just two gripes: it's all very well saying that the Americans were miles
behind, and there was plenty of time for full pressure tests etc and still
be first into the Jet Airliner business. But that's with the benefit of
hindsight, which is always 20/20.
And I find it hard to believe that a designer of RE Bishop's calibre would
allow a major design change - riveting the window surrounds instead of
'Reduxing' them - without checking what effect the drilling of hundreds of
extra holes would have on the structure.
It was also interesting to note that the prototype (the one with
single-wheel main gear) had leading edge slats, which were deleted on the
production machines. I wonder if that's why the wing leading edge on these
early Comets was wrong shaped, leading to the two 'over rotated' take off
crashes? BTW, did you note the clouds of concrete dust as the prototype took
off? The Hatfield runway was still new then - it was a post war addition.
Only broken up a couple of years ago :~(
I must also take issue with something Bill Gunston said - "they always come
unglued, DH aircraft". He was referring to the period between the end of the
war and the Comet disasters - and I can only think of the DH110 in flight
break-up at Farnborough that fits that bill. I don't think Vampires or
Venoms were prone to it (or indeed the Chippy, though that's DHC) - you have
to go back to the pre-war 'Flamingo' to find a 'weak' DH aeroplane. The
biplanes were strong, and all post-Comet DHs were as well (125, Trident,
146).
SSD
Join Date: Apr 2002
Location: over here
Posts: 472
Likes: 0
Received 0 Likes
on
0 Posts
The 'ungluing' reference possibly meant the Mosquito and suchlike non-metallic DH designs as well...they were well ahead of their time in "Composite" technology, but the Mossie's structural problems (Casein Glue, etc) were a hot issue at the time, too.
Gnome de PPRuNe
Join Date: Jan 2002
Location: Too close to Croydon for comfort
Age: 60
Posts: 12,617
Received 293 Likes
on
161 Posts
Interesting programme, well presented I thought; as you say having Bill Gunston, John Cunningham etc, certainly added an authoritative element to the programme, unlike some that I've seen which seem to be mostly supposition by ignorant sensationalists.
I think as Mike Ramsden was quoting Bishop about the rivetting rather than Redux that it must be fact and unlikely to be a case of Chinese whispers! Though I take your point...
DH also had the Albatross break its back pre-war... I'd take issue with the idea that DH had no experience with large passenger aircraft as the Albatross and Flamingo fitted that bill. The public could be excused for thinking that the Mosqutio was the largest aicraft they'd built up to that point.
I didn't think the take-off accident was due to over-rotation, the film they showed of the one sinking back seemed if anything to have under-rotated - it seemed a very flat take off - a later shot showed one taking off with the nose well up. Thoughts anyone?
Didn't BOAC also lose one which was deemed to have been due to a screw backing out and jamming the attitide indicator, leading to too high a rate of climb and a stall? Just wondered if that was actually one of the three accidents referred to last night, as I'd always thought two had pranged due to structural failure. As I recall the three were near Elba, near Stromboli and somewhere in India. The stuck attitude indiactor might have been later on a IV though...
Cheers
I think as Mike Ramsden was quoting Bishop about the rivetting rather than Redux that it must be fact and unlikely to be a case of Chinese whispers! Though I take your point...
DH also had the Albatross break its back pre-war... I'd take issue with the idea that DH had no experience with large passenger aircraft as the Albatross and Flamingo fitted that bill. The public could be excused for thinking that the Mosqutio was the largest aicraft they'd built up to that point.
I didn't think the take-off accident was due to over-rotation, the film they showed of the one sinking back seemed if anything to have under-rotated - it seemed a very flat take off - a later shot showed one taking off with the nose well up. Thoughts anyone?
Didn't BOAC also lose one which was deemed to have been due to a screw backing out and jamming the attitide indicator, leading to too high a rate of climb and a stall? Just wondered if that was actually one of the three accidents referred to last night, as I'd always thought two had pranged due to structural failure. As I recall the three were near Elba, near Stromboli and somewhere in India. The stuck attitude indiactor might have been later on a IV though...
Cheers
Last edited by treadigraph; 14th Jun 2002 at 11:08.
The Aircraft seen in the programme which appeared to be under rotating was definitely the prototype possibly on a pre first flight hop. The crash at Rome & the Canadian Pacific crash both involved the aircraft failing to become airborne in a very nose high attitude. The stuck attitude indicator accident occured to a BEA IVB At Ankara in 1961
Join Date: Oct 1999
Location: UK
Posts: 3,325
Likes: 0
Received 0 Likes
on
0 Posts
I think the one lost to the attitude indicator screw was a BEA Comet 4. It was certainly much later than than the Comet 1 disasters.
I undrstood that the problem with take off on the early Comet 1 was that if the aeroplane was rotated beyond a certain angle, with the mains still on the ground (and it didn't need to be much of an angle) the wing would produce excess drag and insuficient lift, so the aeroplane either wouldn't take off or would not climb away once airbourne and may sink back on. I think this lead to subsequent aeroplanes having to demonstarte 'min speed unstick', to ensure that even if the tail is scraping along the runway, the aeroplane will lift off and climb away safely.
SSD
I undrstood that the problem with take off on the early Comet 1 was that if the aeroplane was rotated beyond a certain angle, with the mains still on the ground (and it didn't need to be much of an angle) the wing would produce excess drag and insuficient lift, so the aeroplane either wouldn't take off or would not climb away once airbourne and may sink back on. I think this lead to subsequent aeroplanes having to demonstarte 'min speed unstick', to ensure that even if the tail is scraping along the runway, the aeroplane will lift off and climb away safely.
SSD
Join Date: Apr 1998
Location: 18m N of LGW
Posts: 945
Likes: 0
Received 0 Likes
on
0 Posts
Bill Gunston - good. Mike Ramsden - good. The FO's - good. But what has that got to do with the cover-up?
What went on was an absolute disgrace. From the moment that aeroplane was built it was an accident waiting to happen. The corners cut were tantamount to criminal negilence, yet not one of the designers, or directors was bought to book when it was so blatantly obvious that they should have been.
The revelations in written form were an indication of how politicians and men in power can manipulate anything they want to. That they manipulated this aeroplane to early destruction is wicked.
Bishop, as head of design, has had his memory degraded by the programme, and that goes for de Havilland too. And quite rightly judging by the standards they adopted. Especially reducing the skin thickness from 14g down to 20g.
Certainly blaming pilots was obviously the 'easy option'. As used to be the case then. Thank God we have now a responsible body to discover actual cause.
Fortunately, the Comet lived after they went back to the drawing board, and removed all the devious schemes. But sad to say that the 1000 planned only reached 75. If only..................
What went on was an absolute disgrace. From the moment that aeroplane was built it was an accident waiting to happen. The corners cut were tantamount to criminal negilence, yet not one of the designers, or directors was bought to book when it was so blatantly obvious that they should have been.
The revelations in written form were an indication of how politicians and men in power can manipulate anything they want to. That they manipulated this aeroplane to early destruction is wicked.
Bishop, as head of design, has had his memory degraded by the programme, and that goes for de Havilland too. And quite rightly judging by the standards they adopted. Especially reducing the skin thickness from 14g down to 20g.
Certainly blaming pilots was obviously the 'easy option'. As used to be the case then. Thank God we have now a responsible body to discover actual cause.
Fortunately, the Comet lived after they went back to the drawing board, and removed all the devious schemes. But sad to say that the 1000 planned only reached 75. If only..................