Assymetric Canberra's
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Assymetric Canberra's
To one and all,
Many thanks for your various responses.
FJJP - thanks again for your contribution, they should keep me occupied for a while.
Stan Evil - there is no odour, just a keeness to discover what really happened.
Beeayeate - the fin has no burn marks whatsoever, with the final vertical motion of the aircraft, the fin would have ended up in the main fire....no burns, no fire! I'm convinced it fell off before the aircraft hit the ground. I also have copies of the crash sight photos which clearly show where the fin would have been if it had remained attached.
However, can we possibly drag ourselves back to my original request for information.
Briefly,we are talking about a Canberra in the 70's that went in during practice asymmentric flying with three crew aboard who all fortunately survived but only just!
In fact the pilot was still in his ejection seat when he 'arrived' in the ploughed field...his seat 'sticker straps' had not seperated from the seat, lucky or what!
Also the approach speed did not drop below the 156kts min at anytime during the finals turn.
I was one of the Navs., and I initiated the ejection sequence for the other Nav when I felt a very violent 'sheer' motion across my nether regions....information which I already have to hand from an excellent source advises me that this 'sheers' movement could have been caused by the fin falling off when the torque tube failed, thus placing a 200% overload on the whole fin structure. This being confirmed by my now having the remains of the fin in my back garden!
The Board of Enquiry was reconvened because the original findings were unacceptable and eventually the whole crew were found negligent in some form or other.
To answer you Oddsoft, I really just wish to get to the bottom of the whole saga, I have no axe to grind and with the revised assy procedures implemented after the PR9 at Wyton, 'wings level - power up', I suspect the numbers of 'practice' assy accidents have been much reduced, I am not talking about all those EFATO's either!!
Cheers aye....Phortz
Many thanks for your various responses.
FJJP - thanks again for your contribution, they should keep me occupied for a while.
Stan Evil - there is no odour, just a keeness to discover what really happened.
Beeayeate - the fin has no burn marks whatsoever, with the final vertical motion of the aircraft, the fin would have ended up in the main fire....no burns, no fire! I'm convinced it fell off before the aircraft hit the ground. I also have copies of the crash sight photos which clearly show where the fin would have been if it had remained attached.
However, can we possibly drag ourselves back to my original request for information.
Briefly,we are talking about a Canberra in the 70's that went in during practice asymmentric flying with three crew aboard who all fortunately survived but only just!
In fact the pilot was still in his ejection seat when he 'arrived' in the ploughed field...his seat 'sticker straps' had not seperated from the seat, lucky or what!
Also the approach speed did not drop below the 156kts min at anytime during the finals turn.
I was one of the Navs., and I initiated the ejection sequence for the other Nav when I felt a very violent 'sheer' motion across my nether regions....information which I already have to hand from an excellent source advises me that this 'sheers' movement could have been caused by the fin falling off when the torque tube failed, thus placing a 200% overload on the whole fin structure. This being confirmed by my now having the remains of the fin in my back garden!
The Board of Enquiry was reconvened because the original findings were unacceptable and eventually the whole crew were found negligent in some form or other.
To answer you Oddsoft, I really just wish to get to the bottom of the whole saga, I have no axe to grind and with the revised assy procedures implemented after the PR9 at Wyton, 'wings level - power up', I suspect the numbers of 'practice' assy accidents have been much reduced, I am not talking about all those EFATO's either!!
Cheers aye....Phortz
Nemesis of the Proot Dynasty
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As a then SNCO Airframe Fitter, who spent some twelve years servicing Canberra B2, B6, B15, B16 and T4 (and occasionally PR9) versions and was present in 1968 at Watton when a well respected crew perished on the airfield attempting a real asymmetric approach, I may be able to add some clarification to the replies which have already been posted.
Torque Tube function – for those who don’t already know, this device was fitted for two reasons. The first and most obvious, was as a buffer between the pilot and the rudder, to dampen extreme and heavy forces applied to the rudder surface. In essence, if the pilot attempted to apply excessive force to the pedals, the torque tube would rotate (twist against the fixed end – one end was fixed rigidly to the fin stub assembly and the other to the rudder. The rudder controls were attached between these extremes) and dampen some of the attempted deflection. The TT was also a device, which allowed the pilot to use the rudder for steering on the ground in high wind forces, when the rudder lock was still in position. Again, for clarification, to stop damage to the rudder and hinges, the rudder ground lock was often left in position until the aircraft was lined up on the centre line. It was then the job of a hapless member of the ground crew, to erect a ladder behind the tail, climb up and remove the lock. An interesting manoeuvre, in a high wind and with engine efflux in your face. I know, because I did it on a number of occasions. By leaving the lock in place, the pilot could still steer the aircraft, even though the rudder itself remained stationary.
I believe it would be unlikely in the extreme, for the fin itself to detach, if the torque tube itself disintegrated, unless other dynamic forces were also present.
Tail Fin – having in the first paragraph, mentioned the versions on the Canberra, with which I was intimately acquainted, I can say with certainty that the majority of the fin assembly, was aluminium. As another ppruner has already ascertained, the skin panels on either side of the leading edge, were indeed plywood (and, I believe in later years, some were fibre glass). But the main structure of the fin was definitely (at least on the versions with which I have mentioned above), aluminium. I modified or repaired enough of them!
I hope the above adds some clarification.
Torque Tube function – for those who don’t already know, this device was fitted for two reasons. The first and most obvious, was as a buffer between the pilot and the rudder, to dampen extreme and heavy forces applied to the rudder surface. In essence, if the pilot attempted to apply excessive force to the pedals, the torque tube would rotate (twist against the fixed end – one end was fixed rigidly to the fin stub assembly and the other to the rudder. The rudder controls were attached between these extremes) and dampen some of the attempted deflection. The TT was also a device, which allowed the pilot to use the rudder for steering on the ground in high wind forces, when the rudder lock was still in position. Again, for clarification, to stop damage to the rudder and hinges, the rudder ground lock was often left in position until the aircraft was lined up on the centre line. It was then the job of a hapless member of the ground crew, to erect a ladder behind the tail, climb up and remove the lock. An interesting manoeuvre, in a high wind and with engine efflux in your face. I know, because I did it on a number of occasions. By leaving the lock in place, the pilot could still steer the aircraft, even though the rudder itself remained stationary.
I believe it would be unlikely in the extreme, for the fin itself to detach, if the torque tube itself disintegrated, unless other dynamic forces were also present.
Tail Fin – having in the first paragraph, mentioned the versions on the Canberra, with which I was intimately acquainted, I can say with certainty that the majority of the fin assembly, was aluminium. As another ppruner has already ascertained, the skin panels on either side of the leading edge, were indeed plywood (and, I believe in later years, some were fibre glass). But the main structure of the fin was definitely (at least on the versions with which I have mentioned above), aluminium. I modified or repaired enough of them!
I hope the above adds some clarification.
Nemesis of the Proot Dynasty
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Just posted a private reply to Compass. However, I was referring to a Torque Tube. Its possible that the name has been changed since 1973 (when I left the R.A.F.), but it was known as a Torque Tube then.
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Have to bow to another rigger (Lukeafb1) with deeper knowledge. Must admit that although I worked Canberras I've only seen inside a fin once and that was in 1963 or so - a T.4 I think. Didn't "work" that one but do have the memory that the ribs were wooden, maybe reinforced by the "wooden" fin story over the years. Intrigued now though, will have to try and force open some memory doors.
Also, apologies to FJJP for possibly duff gen.
I seem to recall however that when they fitted the VOR antenna it had to have a largish circle of copper mesh behind it to act as a reflector, was told this was because of the "wooden" fin. Still, Luke's post implies he has more 2nd line, "hangar", type experience, my time was on squadrons, never really "worked" in ASF. Anyway, as the man says, Canberra fins didn't really "fall off" in flight, don't recall ever hearing of such a thing.
As for the original query, a list of Canberra crashes I have says there was a couple of B.2 practice asymmetric crashes in the UK, one in 1970 and the other in 1973. But both these had fatalities (1k and 2k). Can't find any other asymmetric related prangs for the 70s, plenty in the 50s and a few in the 60s though.
Also, apologies to FJJP for possibly duff gen.
I seem to recall however that when they fitted the VOR antenna it had to have a largish circle of copper mesh behind it to act as a reflector, was told this was because of the "wooden" fin. Still, Luke's post implies he has more 2nd line, "hangar", type experience, my time was on squadrons, never really "worked" in ASF. Anyway, as the man says, Canberra fins didn't really "fall off" in flight, don't recall ever hearing of such a thing.
As for the original query, a list of Canberra crashes I have says there was a couple of B.2 practice asymmetric crashes in the UK, one in 1970 and the other in 1973. But both these had fatalities (1k and 2k). Can't find any other asymmetric related prangs for the 70s, plenty in the 50s and a few in the 60s though.
