Gnat down at CarFest
The aircraft may well have encountered the wake of the other aircraft to cause the initial upset, but it certainly didn't appear to be at low speed.
As mentioned earlier in the thread, possibly a control restriction. I recall we lost a twin-stick Jaguar long ago - being flown solo - when the rear seat PSP and seat straps (not covered by an apron) caused a control restriction.
RIP KW
As mentioned earlier in the thread, possibly a control restriction. I recall we lost a twin-stick Jaguar long ago - being flown solo - when the rear seat PSP and seat straps (not covered by an apron) caused a control restriction.
RIP KW
Unusual Attitude:
In the early evening on the day of the incident, a rather clearer version of the first segment of http://www.telegraph.co.uk/news/avia...s-CarFest.html was out there on the Web. I can't remember who published it (Telegraph??) and now I can't find it via Google videos or You Tube.
In the early evening on the day of the incident, a rather clearer version of the first segment of http://www.telegraph.co.uk/news/avia...s-CarFest.html was out there on the Web. I can't remember who published it (Telegraph??) and now I can't find it via Google videos or You Tube.
https://www.youtube.com/watch?v=R3wld4pvYvw
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High G load departure.
First post here. I have been edified by the recollections of old Gnat hands in response to this unfortunate accident and loss of life, have viewed the videos multiple times and have a couple of observations.
1. Common things occur commonly. Having displayed vintage jet fighters at airshows for years I believe pilot error accounts for the great majority of accidents in general. System or structural failure far less probable.
2. I believe that the videos depict a high G load stall and departure as the aircraft enters its first revolution prior to striking the ground. In the seconds prior to impact the aircraft starts to lose altitude and energy rapidly consistent with a high G stalled airfoil.
Stall speed increases in proportion to the square of the load factor. A 90 degree bank exerts significant load factor which is further increased by the pilot pulling perhaps 6-8G sustained in order to re form with the second ship of the 2 ship formation. Buffet, high ROD, and if not recognized by prompt unloading of the airfoil, evolution to full departure occurs which seems to be what I am seeing.
3. AOA is proportional to relative wind irrespective to attitude. An aircraft accelerating downwards through the vertical can depart if you pull enough G.
4. The other point is that due to the low broken layer of perhaps 2,000 feet or less, they were flying a low show which decreases the margin of safety tremendously.
Pilot error is the default diagnosis when the investigators are able to rule out structural and systemic causes. Statistically in the high performance jet airshow context the former is far more probable than the latter. Many vintage warbird, jet and piston, pilots are lost in this way.We shall doubtless see.
1. Common things occur commonly. Having displayed vintage jet fighters at airshows for years I believe pilot error accounts for the great majority of accidents in general. System or structural failure far less probable.
2. I believe that the videos depict a high G load stall and departure as the aircraft enters its first revolution prior to striking the ground. In the seconds prior to impact the aircraft starts to lose altitude and energy rapidly consistent with a high G stalled airfoil.
Stall speed increases in proportion to the square of the load factor. A 90 degree bank exerts significant load factor which is further increased by the pilot pulling perhaps 6-8G sustained in order to re form with the second ship of the 2 ship formation. Buffet, high ROD, and if not recognized by prompt unloading of the airfoil, evolution to full departure occurs which seems to be what I am seeing.
3. AOA is proportional to relative wind irrespective to attitude. An aircraft accelerating downwards through the vertical can depart if you pull enough G.
4. The other point is that due to the low broken layer of perhaps 2,000 feet or less, they were flying a low show which decreases the margin of safety tremendously.
Pilot error is the default diagnosis when the investigators are able to rule out structural and systemic causes. Statistically in the high performance jet airshow context the former is far more probable than the latter. Many vintage warbird, jet and piston, pilots are lost in this way.We shall doubtless see.
The PPRuNe Military Aviation forum used to be free from the ridiculous speculation which appears on Rumours and News after every airliner accident.
But now the armchair theorists are crawling out of the woodwork over here too - I hope that they will be few and will be ignored by others.
The fact is that a Gnat was involved in a fatal accident at Oulton Park, the cause of which is as yet unknown.
There is no reason to doubt the skills of the late pilot or the professionalism of the team and it is disrespectful for anyone to do so.
Just wait for the accident report, please.
But now the armchair theorists are crawling out of the woodwork over here too - I hope that they will be few and will be ignored by others.
The fact is that a Gnat was involved in a fatal accident at Oulton Park, the cause of which is as yet unknown.
There is no reason to doubt the skills of the late pilot or the professionalism of the team and it is disrespectful for anyone to do so.
Just wait for the accident report, please.
Last edited by BEagle; 4th Aug 2015 at 07:22.
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Flew the Gnat Once
There were some handling problems with the early Gnats which I hope were sorted by the my fellow TPs. Some of those early problems may not be relevant to the current unfortunate circumstance.
Following is an extract from memoirs:
During November 1957, I took the opportunity to fly some more of A Squadron's aircraft. First the Folland Gnat XK767. The Gnat was well named. It was a tiny 'go-kart' aircraft which was very nimble for its day. It had one bad feature which caused the demise of some early pilots. The main wheels were too far to the rear, requiring significant elevator power to raise the nose during take-off. It was vital that the elevator trim be fully nose-up and then extended to an override position to have any possibility of rotation for take-off.
The Gnat I flew had a redesigned elevator system. Instead of a trimable tail plane and separate elevator, this one was the first to have a fully flying elevator. This had given the tail greater effect but had introduced another problem. It suffered severe short-period longitudinal oscillations throughout its speed range. These had been recorded between +5 and -3 g at about 2 oscillation per second. Balance weights and other fixes had greatly reduced the problem. But not before one of Folland's test pilots lost the complete tail assembly at high speed and at low level. He was most fortunate as the tail pitching moment was zero at the time, thus giving him time to eject.
If anything I was over-briefed on the take-off problem to the exclusion of other aspects. On the ground, I found I could stand beside the cockpit and lean my head inside to be able to see all controls and switches. There was still the need for the trim over-ride. The control was a separate switch low on the right side of the instrument panel. This was badly placed, requiring a change of hands to operate.
I took care to set the trim over-ride and to release the brakes with the stick hard back against the stops. The extent of acceleration surprised me and in very little time the nose was pitching up and it was time to raise the undercarriage. The nose wheel door served as the speed brakes and there was a transient trim change as it retracted. I instinctively tried to dampen out the trim changes and found to my dismay that I was out of phase. As this was happening the words of the briefing pilot came back to me. "Don't try to follow the trim changes as the gear retracts."
The nose pitched up and down with each pitch more than doubling. Within two seconds I was alternating from a diving attitude towards the runway to a steep climb. Self preservation prompted me to pull the stick hard back holding back pressure. The aircraft damped the oscillations quite rapidly as I zoomed up into the start of a loop. It was easier to relax as I put more space between me and the runway and soon had it all sorted out.
Full fuel load was about 1500 pnds. With the V Bombers, I was used to getting back near the airfield with 10 to 15 thousand pnds minimum. I mentally added a zero to the fuel contents to prevent any preoccupation with the small fuel quantity. I had decided to be back in the circuit with no less than 300 pnds remaining.
I climbed to 45,000 ft over the sea and flew a few dives to go supersonic. The transient trim changes could be readily managed by the new flying tail and I found that any tendency to 'JC' would cease if the grip on the stick was released. This meant that trim had to be maintained with care.
In next to no time, the fuel gauge was insisting that I go back to base. I joined on a long down wind leg and slowed down to drop the gear. There was a large trim change as speed reduced which was readily accommodated by the normal trim. I noted that the nose-up trim remaining was negligible, as I selected gear down. Whoops - now I have the stick against the rear stops and the nose is still going down. Oh yes - I was told to expect this - use the over-ride - that switch down there on the vertical part of the instrument panel. I change hands and grab the switch, instinctively pushing it down. Whoops again - that was the wrong way. Now I am about 20 degrees nose down with the ground coming up too fast for comfort. A quick reversal of the switch and it reverts to being a controllable aircraft again. To me, that switch was operating in the wrong sense.
About this time, the tower called up to say that there was an English Electric Lightning joining the circuit with a company pilot on his first flight into Boscombe and would I give him priority for landing. I did a double take and called the Lightning pilot and asked him for his fuel state. He had over 1000 pnds. I was down to 250 pnds and now somewhat twitchy. The Lightning pilot defused the situation by declining any need for priority as I guided that little Gnat down on to the runway with some feelings of relief, considering the fuel remaining.
Following is an extract from memoirs:
During November 1957, I took the opportunity to fly some more of A Squadron's aircraft. First the Folland Gnat XK767. The Gnat was well named. It was a tiny 'go-kart' aircraft which was very nimble for its day. It had one bad feature which caused the demise of some early pilots. The main wheels were too far to the rear, requiring significant elevator power to raise the nose during take-off. It was vital that the elevator trim be fully nose-up and then extended to an override position to have any possibility of rotation for take-off.
The Gnat I flew had a redesigned elevator system. Instead of a trimable tail plane and separate elevator, this one was the first to have a fully flying elevator. This had given the tail greater effect but had introduced another problem. It suffered severe short-period longitudinal oscillations throughout its speed range. These had been recorded between +5 and -3 g at about 2 oscillation per second. Balance weights and other fixes had greatly reduced the problem. But not before one of Folland's test pilots lost the complete tail assembly at high speed and at low level. He was most fortunate as the tail pitching moment was zero at the time, thus giving him time to eject.
If anything I was over-briefed on the take-off problem to the exclusion of other aspects. On the ground, I found I could stand beside the cockpit and lean my head inside to be able to see all controls and switches. There was still the need for the trim over-ride. The control was a separate switch low on the right side of the instrument panel. This was badly placed, requiring a change of hands to operate.
I took care to set the trim over-ride and to release the brakes with the stick hard back against the stops. The extent of acceleration surprised me and in very little time the nose was pitching up and it was time to raise the undercarriage. The nose wheel door served as the speed brakes and there was a transient trim change as it retracted. I instinctively tried to dampen out the trim changes and found to my dismay that I was out of phase. As this was happening the words of the briefing pilot came back to me. "Don't try to follow the trim changes as the gear retracts."
The nose pitched up and down with each pitch more than doubling. Within two seconds I was alternating from a diving attitude towards the runway to a steep climb. Self preservation prompted me to pull the stick hard back holding back pressure. The aircraft damped the oscillations quite rapidly as I zoomed up into the start of a loop. It was easier to relax as I put more space between me and the runway and soon had it all sorted out.
Full fuel load was about 1500 pnds. With the V Bombers, I was used to getting back near the airfield with 10 to 15 thousand pnds minimum. I mentally added a zero to the fuel contents to prevent any preoccupation with the small fuel quantity. I had decided to be back in the circuit with no less than 300 pnds remaining.
I climbed to 45,000 ft over the sea and flew a few dives to go supersonic. The transient trim changes could be readily managed by the new flying tail and I found that any tendency to 'JC' would cease if the grip on the stick was released. This meant that trim had to be maintained with care.
In next to no time, the fuel gauge was insisting that I go back to base. I joined on a long down wind leg and slowed down to drop the gear. There was a large trim change as speed reduced which was readily accommodated by the normal trim. I noted that the nose-up trim remaining was negligible, as I selected gear down. Whoops - now I have the stick against the rear stops and the nose is still going down. Oh yes - I was told to expect this - use the over-ride - that switch down there on the vertical part of the instrument panel. I change hands and grab the switch, instinctively pushing it down. Whoops again - that was the wrong way. Now I am about 20 degrees nose down with the ground coming up too fast for comfort. A quick reversal of the switch and it reverts to being a controllable aircraft again. To me, that switch was operating in the wrong sense.
About this time, the tower called up to say that there was an English Electric Lightning joining the circuit with a company pilot on his first flight into Boscombe and would I give him priority for landing. I did a double take and called the Lightning pilot and asked him for his fuel state. He had over 1000 pnds. I was down to 250 pnds and now somewhat twitchy. The Lightning pilot defused the situation by declining any need for priority as I guided that little Gnat down on to the runway with some feelings of relief, considering the fuel remaining.
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Fascinating
Milt,
Thank you for sharing - you flew in interesting times and there will be time for further discussion I am sure.
I guess that they (you TPs) solved many of the points that you mention as the RAF ended using the Gnat for training and the Red Arrows.
Thank you for sharing - you flew in interesting times and there will be time for further discussion I am sure.
I guess that they (you TPs) solved many of the points that you mention as the RAF ended using the Gnat for training and the Red Arrows.
Gentleman Aviator
Heard Chris Evans' few words on my way to work this morning - they were exactly right and to be applauded.
He was obviously very shaken on the day from the TV interview, but today - his first day back at work - he was very impressive.
He was obviously very shaken on the day from the TV interview, but today - his first day back at work - he was very impressive.
Chris Evans I believe is a Robinson qualified pilot and his sentiments to the pilot and his family this morning on air were obviously hard for him to speak about. He has an air interest as well as car interest and so by default, as all pilots do, will have a fondness for all professional pilots who fly to entertain us.
I did have to put my mug down and share his sympathy due to his tone, empathy and obvious tear....
Coley
I did have to put my mug down and share his sympathy due to his tone, empathy and obvious tear....
Coley
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It was quite poignant at North Weald on Monday as Chris Heames ferried back the other Gnat from Hawarden.
Working in North Weald Ops, I have spoken to Kevin and the other Gnat pilots on numerous occasions. They always tried their best to fit in around our diverse traffic – from microlights to biz jets. Working in the Tower on Saturday when the news of an incident started coming through was not easy. Here are a few pictures of happier times...
RD
Working in North Weald Ops, I have spoken to Kevin and the other Gnat pilots on numerous occasions. They always tried their best to fit in around our diverse traffic – from microlights to biz jets. Working in the Tower on Saturday when the news of an incident started coming through was not easy. Here are a few pictures of happier times...
RD
R/e speculation.
Please - this is a rumour network.
Speculation as to accident causes has no place in an operational context.
It may lead to an investigation going astray, or operational pilots focusing on erroneous supposed causes, unnecessarily modifying SOPs and/or creating additional hazards.
But I'd suggest speculation on a forum like this is entirely appropriate - we speculate out of a passion for flight, wanting to learn and understand, and certainly not to malign a fellow pilot much more experienced than many of us who has tragically lost his life.
Please - this is a rumour network.
Speculation as to accident causes has no place in an operational context.
It may lead to an investigation going astray, or operational pilots focusing on erroneous supposed causes, unnecessarily modifying SOPs and/or creating additional hazards.
But I'd suggest speculation on a forum like this is entirely appropriate - we speculate out of a passion for flight, wanting to learn and understand, and certainly not to malign a fellow pilot much more experienced than many of us who has tragically lost his life.
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I think the "thou shalt not speculate prior to the AAIB report", is a little hopeful and naive for an internet rumour forum is it not?
However, it is neither speculative nor insensitive to query an aviation fact on here, post accident IMHO (if it is...seems to me this site is pointless).
So, did this unfortunate chap qualify for his RAF wings of not? (not only a fact; a polarised yes/no fact as well).
If he did not...the inference that he was a military pilot is flat wrong and misleading. It should be rebutted.
I don't know the answer; hence the question. There seems to be some doubt in the articles I have read, including his obituary in The Times.
If he wasn't, I am not implying any follow up notion that his abilities were anything other than they should have been to undertake this type of flying (so don't imply please that this is a fishing trip - coz it ain't!).
I'm merely trying to answer a yes/no question.
However, it is neither speculative nor insensitive to query an aviation fact on here, post accident IMHO (if it is...seems to me this site is pointless).
So, did this unfortunate chap qualify for his RAF wings of not? (not only a fact; a polarised yes/no fact as well).
If he did not...the inference that he was a military pilot is flat wrong and misleading. It should be rebutted.
I don't know the answer; hence the question. There seems to be some doubt in the articles I have read, including his obituary in The Times.
If he wasn't, I am not implying any follow up notion that his abilities were anything other than they should have been to undertake this type of flying (so don't imply please that this is a fishing trip - coz it ain't!).
I'm merely trying to answer a yes/no question.
Gnat PFCUs
A point, probably of no significance whatsoever. The two Gnats in the photos above, although both TMk1s, have a slight difference. The ex-Red Arrows aircraft has a Mark 4 Hobson unit (tailplane PFCU) and the ex-Valley Gnat in the "Mr Whippy" colour scheme has the more sensitive Mark 5 unit.
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Quals
The Old Fat One,
I think....
208 Tucano then Valley Hawk course - left part way through.
Importantly,
Gnat for 8+ years, flown this display 75+ times.
No conclusions this end but fairly sure that the above are factual...if it not actual facts.
RIP
I think....
208 Tucano then Valley Hawk course - left part way through.
Importantly,
Gnat for 8+ years, flown this display 75+ times.
No conclusions this end but fairly sure that the above are factual...if it not actual facts.
RIP
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'Don't speculate; wait for AAIB' crops up on here and other places too. It's bollox. We are all passionate about flight and this is an appropriate place, a rumour network - of course we'll speculate (speculation doesn't include 'it was definitely caused by X', of course).
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LEVITT: So we wrote Freakonomics, and because it was deemed a business book and we sold a lot of copies, that made us business experts. And since we wrote that book I’ve been asked a ton to go talk to companies and give them advice. And what’s amazing to me is I could count on one hand the number of occasions in which someone in a company, in front of their boss, on a question that they might possibly have ever been expected to know the answer, has said “I don’t know.” Within the business world, there’s a general view that your job is to be an expert. And no matter how much you have to fake or how much you are making it up that you just should give an answer and hope for the best afterwards. And I have seen it teaching the business school students, that they are incredibly good — the MBAs — at faking like they know the answer when they have no idea.
So everybody hold hands and say "We don't know"
So everybody hold hands and say "We don't know"