View Full Version : Spinning the Gloster Javelin
8th Nov 2011, 20:20
Reposted here from history/nostalgia boards for your attention on the recommendation of Kitbag:
I wonder if you knowledgeable chaps could please settle a disagreement over a certain incident?
Having read various articles on the Gloster Javelin, my understanding is that above 45 degrees attack angle, the delta wing cuts off all airflow to the t-tail, the plane stalls, and then drops vertically out the sky like a flat iron with no way to recover it due to zero airlflow over the control surface. Thus as Peter Lawrence found out with unfortunately the ultimate cost.
A friend of mine, who happens to be an ex- chipmunk pilot reckons that "Much like a flat spin experienced by anyone running out of lift with an over generous aoa then. Peter Lawrence simply ran out of opportunity to recover. Even a delta formation with no airflow over the surfaces has a limited amount of control. Given enough alitude a skilled crew will recover"
So, was the situation ever recoverable? Or was Lawrence as sadly doomed as all the official accounts seem to suggest?
Genghis the Engineer
8th Nov 2011, 21:12
I'm firmly post-Javelin, but you could do worse than try the National Records Office at Kew - their website is generally good for old military records, although you may have to contribute a few beer nuggets to the exchequer to get somebody to scan them in for you. The search function on their website is pretty good for WHAT they've got however.
8th Nov 2011, 21:25
Bill Waterton, chief test pilot on the Javelin, notes in his book "The Quick and the Dead", that the tailplane was found to be trimmed in the opposite direction to be expected to enable recovery. One previous stall had been carried out, and the fatal stall was with flaps down. He notes that elevator control was "sluggish" at low speed. At the time of writing the book (1955) results of the accident investigation had not been released, even though he the chief test pilot had asked for a copy from the Air Ministry.
Found the following on Aircraft Profile #179. Gloster Javelin (http://www.aviastar.org/gallery/javelin.html)
High altitude flying on the first two prototypes had shown that the high speed handling characteristics could be improved by modifying the outer wing. From just outboard of the guns, the leading edge sweep back was reduced thus increasing the tip chord and reducing the thickness/chord ratio. The decrease in taper ratio reduced the span wise flow and consequently improved the tip stalling characteristics and the lift coefficient at high subsonic Mach numbers. A modified set of wings was fitted to WD808 in time for a first flight on 28th May 1953, But only a fortnight later disaster struck again, this time with grim results. Peter Lawrence was flying WD808 on Nth June, doing stalling tests with the C.G, further aft than normal. During a test at a high angle of attack, the "super stall" condition developed, where the nose of the aircraft pitches up and the forward speed decreases rapidly. Below about 80 knots the condition is virtually stable and, despite all Lawrence's efforts, he could not regain control. Unfortunately he must have misjudged his height and, when he finally ejected, he was too low for his parachute to deploy completely. Thanks to the information he had given over the radio and the auto observer records, a complete dossier was made out.
Again testing was held up while an answer was sought. Wind tunnel tests, at high angles of attack confirmed the "super stall conditions. The main cause of the trouble was tip stalling which rapidly spread to the rest of the w ing at high angles of attack. Having the flaps down aggravated the condition so the front edge of the flaps were cut back to give a semi slotted effect. This improved things but did not cure the tip stalling. Model tests with leading edge droop showed no improvement but wind tunnel tests on slotted wings gave promise of a cure. Consequently a set of wings with slats of constant percentage chord was test flown and the stall became innocuous. But the weight penalty (130-180kg) and the cost were not acceptable to cure a conditions which need never occur.
Consequently a stall warning device was developed which proved effective. A small metal flag with a rotating mast was fitted at about mid span of the outer wing. At rest, a spring held the flag at right angles to the line of flight and a set of contacts were closed. When the aircraft took off, the airflow moved the flag round into line of flight position and opened the contacts. When the undercarriage retracted, a circuit to a sound box, operating on the intercom, was made except for the flag contacts. Should the airflow over the top surface of the wing start to break down, the disturbed flow would no longer hold the flag against its spring, the contacts would close and the pilot would get a warning note in his headphones.
Apart from this audible warning there is little else to warn the pilot of an approaching stall. If the nose is held up below 185km/h the speed will drop off rapidly and finally the aircraft will yaw uncontrollably to one side and roll in the opposite direction before falling into a spin.Interesting to note the CofG further aft than normal - too far aft perhaps? An SR-71 was lost during test because the CofG was too far aft and control was lost.
8th Nov 2011, 21:31
ah thanks for the info. As far as I have read though, though stalling normally did lead to spinning that may or may not have been recoverable, a deep stall like Lawrence's one apparently simply made the aircraft plummet vertically? is that possible or is it artistic licence employed by the author who penned the account of it?
8th Nov 2011, 21:53
207 Squadron RAF Association - AVM David Dick (http://www.207squadron.rafinfo.org.uk/ADDobit.htm)
Try this. Had a first hand account of the whole thing from the man himself. A truly remarkable aviator.
8th Nov 2011, 22:17
though stalling normally did lead to spinning that may or may not have been recoverable, a deep stall like Lawrence's one apparently simply made the aircraft plummet vertically?Javelin Pilot's Notes gave us a minimum IAS limitation of 150 knots "except on final approach " and prohibited aerobatics in the looping plane; intentional stalls were also banned and, since there was apparently no way to recover from the stalled condition, the Notes' recommended procedure in event of an unintentional stall was to induce a spin from which a recovery might be achieved by use of aileron, the rudder and tailplane being sufficiently blanked by the wings as to be ineffective.
8th Nov 2011, 23:05
Thanks very much for the info chaps! I am once again in awe of your encyclopaedic knowledge!
9th Nov 2011, 04:16
henry crun provides the following information at http://www.pprune.org/flying-instructors-examiners/61378-flying-instructors-who-refuse-spin-7.html
If stalled the aircraft would almost inevitably spin.
The direction of spin is usually unpredictable, even from turn to turn.
The rotation is very slow, and the nose pitches up and down fairly regularly, through as much as seventy degrees. The rates of yaw and roll will vary with the pitching. The stick forces are very light throughout, and there is no 'kick back'' on the stick. However, the rudder moves fiercely fully one way and the other, and the forces may be extremely heavy; it is recommended that the feet are merely kept lightly on it throughout the spin. The airspeed varies from "off the clock" to about ninety knots.
When the aircraft is clearly in a spin take the following action;
i) With the control column fully back apply full aileron in the same direction as the spin.
ii) With full aileron applied, move the control column fully forward into the corner.
iii) Keep the feet lightly on the rudder pedals.
It is unlikely that this action will have any effect for one or even two turns; certainly it seldom has any immediate result. The control column should be held fully in the corner; the direction of spin may reverse, and in this case the control column should be held right forward and moved sharply fully over into the new direction of spin.
No force should be used to oppose any rudder movement.
Recovery generally follows one of two main patterns, type (i) being the more usual:
i) The rotation ceases, and the aircraft hangs in a nose-down attitude for a second or two. However the control column must still be held fully in its corner until the aircraft does a sharp nose-down pitch or "bunt". Minus 2 1/2g is about the usual figure for this and is quite unmistakable.
Once the aircraft has done this, the spin has stopped.
The speed rises rapidly, and only then should the controls be centralized, and the aircraft eased out of the dive. Attempts to centralise the controls and recover in the stage when the rotation has ceased, but before the aircraft has "bunted", will lead to a further spin with delayed recovery.
ii) After taking recovery action, the aircraft enters a fast spiral in a steep diving attitude. The spiral may be in the same direction as the applied aileron, or against it, but this condition may usually be recognised because: a) the pitching ceases, b) the speed rises, c) the rate of rotation is steady and fast. Once the speed is over 200 knots, the controls may be centralized, and the aircraft eased out of the dive. The rudder will centralist itself when recovery is complete, and it should be left to its own devices.
9th Nov 2011, 12:14
It will all be in the book that I'm not allowed to mention ;)
13th Nov 2011, 20:56
I have the Pilots Notes for all marks of the Javelin. They all say 'Intentional stalls and spins and aerobatics in the looping plane are prohibited'. An audio warning was sounded when the aircraft speed fell below 150 kts.
15th Nov 2011, 01:20
They all say 'Intentional stalls and spins and aerobatics in the looping plane are prohibited'. An audio warning was sounded when the aircraft speed fell below 150 kts.
That sounds like the best advice posted, so far!