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robunos

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Regarding the aerodynamic problems with the Swift; this from Gunston's 'Fighters of the Fifties, pp.228-9 :-

"To accommodate the ammunition for the extra pair of guns ( the original Swift only had two guns, the RAF required four ) the inboard leading edge was kinked forward, and this caused unacceptable pitch-up when pulling even modest g at Mach 0.85 or above . . . More than 45 trial modifications to the wings sought to eradicate pitch-up, the final standard including dog-teeth and extended outer sections."

My edit in brackets.

cheers,
Robin.
 

zen

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From Philip Birtles "Attacker, Swift and Scimitar" (ISBN 0 7110 2034 5)
( on the F2)
"However the modified wing root resulted in violent pitch-up when g was applied at Mach 0.85 and above, a highly undesirable characteristic in a combat aircraft."

"In an attempt to overcome the problem a wing fence was fitted on the top surface of the wing and the leading edge was extended forward in a small step at about half-span.
This did not prove to be a fully effective answer, the idesl cure being to move the centre of gravity forward. However this could only be achieved by fixing heavy balast weights in the nose, which limited the high altitude performance."
 
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T. A. Gardner

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I'm unclear what where really the root causes of the Swift and early Hunter issues. Not sure what could have been done besides "design them better"

Maybe just luck. Every country produced plenty of turds around that point. Swift was far from the worst. e.g. Vought went from F4U to F6U to F7U....and them redeemed themselves with the F8U.
Most of the problems with both relate to the engine. The RR Avon proved about as unreliable as the Westinghouse J 34. On the Hunter, the guns were positioned where when fired, the smoke got ingested into the intakes and caused a compressor stall as an example. Both planes had major issues with that just as several US Navy planes had with the J34.
Unlike RR, Westinghouse never did really get things right and eventually that led to their decline and exit from the jet engine business after a promising start.
 

starviking

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I'm unclear what where really the root causes of the Swift and early Hunter issues. Not sure what could have been done besides "design them better"

Maybe just luck. Every country produced plenty of turds around that point. Swift was far from the worst. e.g. Vought went from F4U to F6U to F7U....and them redeemed themselves with the F8U.
I’d say better post-war research would help. Donald Wood mentions a near moratorium on research until around 1950.
 

Bounce

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When I read the title my mind imagined a modern built Spitfire, full carbon fuse/wings/glass cockpit and an over powered turboprop.

If only I had Jeff Bezos money...
 

Opportunistic Minnow

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The RR Avon proved about as unreliable as the Westinghouse J34.
Yet the Avon was in active service as late as 2006 on the Canberra and the J34 must have made it into the 80s with the P-2H (does anyone know when the T-2A was retired?). Not bad for failures! Proof if ever there was that airframe/engine integration is a fraught exercise.

I've always wanted to put the Swift's rotundity to good use and put a Conway in one myself.
 

zen

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RR was getting progress with the Avon by the time of the Swift. But the inlet issues caused a host of problems. Not really fair to try to blame RR on this, Supermarine were learning the hard way about this.
 

tomo pauk

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RR was getting progress with the Avon by the time of the Swift. But the inlet issues caused a host of problems. Not really fair to try to blame RR on this, Supermarine were learning the hard way about this.

I do recall that it took a while for the Avon to be a good engine as we recall nowadays. IIRC at the book about the Pegasus engine it was said something along these lines: Yes, Rhubra made the Avon, but it took a redesign to make it actually work.
 

Hood

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Some Swift moans from the files (its worth noting that Hawker had their own problems and got it in the neck just as much over delays in fixing problems, luckily for them the Hunter seemed to come right in the end, the Swift just seemed never to improve enough and in the end was canned and should probably never have been begun without a proper OR and rational design rather than the knee-jerk reactions to MiGs over Korea).

Minute 7/Acft/11950 ‘Swift F.Mk.2 – Conditions of Release to the Service’ by R.D.L.4 L. Johnston to D.O.R.1, 3/6/54
Vickers are investigating various means of removing the tendency to tighten in turns. Some of these are easy changes and others such as the dropped leading edge and faired tooth are more difficult to apply.
A Mk/2 aircraft with c.g. move forward, improved tensioning in the elevator circuit, modified stick-elevator gearing and elevator tab movement has been flown by the firm. They consider that in this condition the aircraft characteristics are much the same as the Mk.1 and if agreed by AAEE a C.A. Release on the same terms as for the Swift Mk1 could be given.
Time for wing mods cannot be estimated nor for retrospective fitting.

Loose Minute to P.S. of S. of S., undated but after 14/4/54
Turning Circle – variable incidence tail will improve the turning circle a little. More importance contributions to a reduction in the turning circle are the application of re-heat and a flying tail…Mk.4 to have reheat and variable incidence tail… not able to say when flying tail will be introduced… the turning circle of the Mark 4 Swift with re-heat unlit is likely to be even greater than that of the Mark 1.
Turn Round Time – The Swift started life as a P.V. and made the minimum allowance for radio equipment; it has since proved difficult to provide a really satisfactory radio layout. At present it takes up to 1.5 hours to change the second V.H.F. set; however, for this particular equipment an alternative position has now been found…Access to the engine starting equipment will be improved in the Swift Mark 3 and later Marks.
Aerial System – The present system was the best that could be provided if the aircraft was not to be further delayed. An improved external aerial should be ready for test shortly. Supressed aerial may follow later but firm’s proposal for canopy aerial incompatible with canopy de-icing.
Improved Vision – Improved canopy discussed and approved by M.C.S., firm, Fighter Command and D.O.S. in August 1952 will be introduced on Mk.4. Ejector seats better than US ones (fully automatic) but do block some rear view.
Over-spill of fuel – This is caused by faulty design in the vent pipe system. A modification is being introduced to raise the level… of the vent pipe.
Hunter prepared to an O.R. and should be better in regards to servicing.
Now reasonably confident that by early June a C.A. release will be forthcoming and at the same time Hunters with essential modifications incorporated will be available in quantity.
Hunter will be more manoeuvrable but suffers from same aerial problem, firms lack experience on this subject.

Loose Minute ‘Trial of the Swift No.1 at C.F.E.’ by A/A.C.A.S. (Ops.) Air Commodore K.B.B. Cross to DCAS, 19/3/54
ACAS(OR)’s minute of 15/3/54 does not accentuate sufficiently the shortcomings of the Swift, especially when compared to Sabre (in service 5 years and Swift planned in service until 1959/60).
CFE are thoroughly disappointed with the elevator control… Above Mach 0.9 the elevator becomes progressively less effective as height is increased, and at 40,000ft the stick can be moved as much as 4in fore and aft without response… becomes acute when the airbrakes are operated in dives at high Mach numbers. Under these conditions the elevators are totally ineffective until the air brakes are retracted again… not satisfied a variable incidence tail will make improvements in combat handling due to use of tail trimmer throughout diving attack… Is not the proper answer to press for a fully flying tail and an improved power control system?
Engine surging and compressor stalls not dangerous in normal flying… but are totally unacceptable under combat conditions, and remedial action must be taken urgently.
The present limitations make the Swift a poor combat aircraft even in the limited role of bomber destroyer. In the fighter v. fighter role, which the Swift will certainly have to undertake in 2nd T.A.F, if not in the U.K., these failings do not give it even a fighting chance in combat.

Loose Minute Swift Acceptance Conference by Wing Commander H.J. Cundall to D.O.R.(A), 19/11/54
Boscombe Down stand firmly by their opinion that, while the handling characteristics of the Swifts have greatly improved, the Marks 3 and 4 are still not in a condition to permit release to the Operational Command. Turn tightening largely removed but elevator effectiveness at speeds above M0.96 not yet satisfactory. Limits easily reached at M0.9 at max level speed without reheat.
By using the V.I tail trimmer as a flying control, in some conditions serious turn tightening can be induced, Ineffectiveness of elevators encourages greater use of the V.I. tail, restrictions might not be observed in service conditions.
Flying qualities of Mark 3 nearer acceptable release standard due to larger elevators lacking from Mk.4 due to V.I. tail.
Further boosting on Mark 3 may suffice and a simple modification expected to be available for Boscombe Down trials within a week or so. Report in December. Mark 4 more extensive, redesign of the elevator and greater power boosting or early introduction of full flying tail. Unofficial estimate of effective delay to delivery is three months.
Shock to hear despite their high priority requests for flying tail, the firm has a low priority. A clause from the contract was quoted from memory by the production representatives of the firm calling for development of the flying tail with “the least possible expenditure of public money”. DMARD astonished and undertook to get contract amended. Firm estimated the flying tail may fly before end of December with raised priority.

Loose Minute Swift Aircraft – Pilot Ejection by Sqn Ldr D.R. Kingaby Ops.(A.D.)1, 23/11/54
In Swift Fortnightly Narrative Report No.2 dated 8/11/54, stated pilots of above average height or body length are unfavourably placed for ejection, cannot safely raise arms to the ejection blind without their elbows entering the slipstream. Removing the exposure suit from the set pack necessary. Only regarded as an interim measure, request to investigate methods to ensure safe ejection.

Loose Minute Swift Strength Factors by Gp Capt H.N.G. Wheeler D.D.O.R.1 to A.D/R.D.L.1 12/11/54
Modification No.237 recently considered by the A.M.C. Strengthens fuselage at the wing spar attachment and between frames 31 and 33, will be embodied in 87th aircraft onwards, probable weight restrictions on unmodified Mk.2 & 4 aircraft.
Committee ruled this situation unacceptable, asked firm to state the production delay involved in bringing embodiment forward to first Mk.4 aircraft and the nature of the weight restriction.
Case only part of general strength factors. Previously wrote 25/7/54 on this issue and wants further advice.
Unwilling to accept any Swifts with restrictions on them. Should apply mods before service release and if not able to, should make mod applicable retrospectively.

Minute Swift – Variable Re-heat by H.G. Knight Eng.R.D.2. to R.D.L.4, 14/10/54
Further to loose minute to O.R.1(b) 27/9/54, Rolls-Royce suggest not long before variable reheat can be cleared, action should now be initiated to apply modifications to throttle control.
Modification is mainly embodying micro-switches in such a manner that a certain amount of adjustment in position is possible.

Minute Swift – Variable Re-heat by H.G. Knight Eng.R.D.2. to R.D.L.4, 27/9/54
Reply to loose minute 30/8/54, bench and flight tests at Rolls-Royce underway. Two difficulties have arisen which need a certain amount of redesign.
A considerable change in RPM at a given throttle setting occurs with change of altitude, under certain conditions the whole control systems becomes unstable.
Probably 3-6 months before recommending a scheme for service use.

Minute Swift – Flying Tail by DMARD(RAF) to D.O.R.(A) 24/9/54
Response to minute 1/9/54, we raised the question of a flying tail nearly a year ago, firm prepared a scheme and a contract was placed last March for a trial installation.
Should be ready for flight trials before the end of the year.
Considering advisability of putting tail into production aircraft without waiting for test results, will recommend this if risk is reasonable. Retrospective fit feasible if aircraft returned to works.
We see no grounds for rejecting Swift with V.I. tail, should be broadly similar to Hunter 1 & 2 but has advantage of extra fuel and reheat.
[Handwritten note at bottom by DOR(A) to DDOR1 “No immediate action on this pending the outcome of own recommendation on the future of the Swift + also the Boscombe trials with the VI tail BF in one month”]
 

zen

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Hood thank you for posting that lot.

Does rather show the tortured path this effort took.
 

Hood

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The problems with the Swift and Hunter were examined in some detail by the Air Staff during 1953-54 and show the Swift wasn’t alone in having issues.

Hunter
- Integral fuel tanks abandoned due to technical reasons
- Requirement Armour protection for pilot added by Air Staff
- Additional radio equipment added as the Air Staff changed method of operational control
- Airframe changes after ADEN cannon barrel shortened
- In September 1951 airbrakes found unsatisfactory, 12 months of tests unsuccessful (wind tunnel tests had shown possible problem but not how serious), flying resumed July 1953 and by December airbrakes found unsatisfactory, due to lack of aircraft and experimental capacity Hawker was unable to pursue alternative solutions at the same time.
- Problems with wheelbrakes
- Problems with tail flutter
- Tightening in turns, stalling and spinning and power control problems were being revealed by late 1955
- Biggest reason for delay is from ordering too many Hunters, planning for 96 per month meant Blackpool had to be acquired and fitted out with tools etc. when if smaller amounts had been ordered Hawkers and A.W could have coped alone.
- Design staffs of Hawkers and Vickers overloaded with work of all types including GW

Swift
- Ordered off drawing board as the 535 was deemed to have reduced the risk – turns out not so
- RAE Report of Dec 1950 that criticised manoeuvrability of Swift at high altitudes due to poor lift characteristics was largely based on wind tunnel tests and not shown “precisely what needed to be done to improve the lift characteristics.” Suggested blunt leading edge section was the cause and suggested improvements by using boundary layer fences, incorporated in April 1954 and January 1952 respectively. MoS and RAE discussed with firm and decided to go ahead as designed and accept shortcomings that could not be rectified as major re-design of wing was impractical in the timescale
- February 1952 an American team (probably connected to application to MDAP funds) felt redesign needed, Chief Designer confident though that modifications would alleviate problems “to an acceptable degree” (at the same time VA argued the Swift had greater development potential than the F-86!)
- Air Staff not aware of aerodynamic difficulties until MoS meeting December 1952
- Forward movement of c.g. to cure longitudinal instability
- Redesign of intakes
- Design and introduction of variable incidence tailplane
- Replacement of Lockheed servodynes with Fairey boosted power controls as insurance
- Due to an Valiant accident, extra fire prevention arrangements were added which cost 7 months
- Flutter grounded the aircraft for 3 months in late 1952
- 2 months delay during mid-53 due to compressor blade fatigue failures and engine surging
- Nov 1953 fatal loss of 2nd aircraft caused further delay.
- Tightening in turns worse than Mk.2,3 & 4
- Leaking fuel tanks
- Power control failure
- Trouble with spinning and stalling
- Considerable delay caused by fitting reheat for the world speed record which was only held a few days
- It was considered that only the Mk.4 would meet OR.228 due to lack of one when work began on the previous marks
- Design staffs of Hawkers and Vickers overloaded with work of all types including GW
- Squadron trials ground to a halt given the deficiencies. August 1954 the CFE said it was unlikely the Swift would ever be suitable. Still hoped intensive development could solve problems and Mk 4 was seen as front line aircraft. - - Not until late 1954-early 1955 was final decision made based on report on trials by Boscombe Down and CFS. Inadequate manoeuvrability over 40,000ft and high-altitude endurance unacceptable as need full reheat to maintain operational altitude. Also instability when using dive brakes at high speeds, inaccessibility for maintenance and control difficulties if the power control system failed.

Add onto that serious problems in drafting and multiple re-issues of OR.228 with continual changes, breakdown of communications with the MoS who declined to tell the Air Staff bad news, accusations of receiving bad technical advice in return.
During 1951-52 Swift appeared on paper better than Hunter and at December 51 meeting C-in-C, Fighter Command concluded orders should be increased.
Swift Mk 4 numbers increased by cutting orders for Mks 1-3. MoS wanted to order 136 more to secure 35 per month rate and this would be balance of Plan K requirement to March 1956. Resisted by F.6 and approach to Treasury limited to 75. Approval given August 1953. Hunter still doubtful and on 9/6/53 MoS told to stop future developments of Hunter and concentrate on Swift.
In May 1954 MoS advised ordering another 100 Swifts to relieve unemployment at Shorts. Well within 963 requirement for Plan K (Star) but Air Min refused to consider the proposal.

In all a complete bog-up but at least not a complete washout.
Would the Swift have been a complete mess? The PR.5 seemed to operate ok so perhaps it might not have been any worse than many other fighters of its generation, certainly boasts about it being faster than a MiG-15 meant very little by 1957 though.
 
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