SEPECAT Jaguar Supersonic Claim

[Hood]

In Aeroplane Monthly's issue this month, there is an article on the SEPECAT Jaguar M by J C Carbonel (which can also be found online here: https://www.key.aero/article/seacat).

In it, Breguet engineering project manager Jacques Desmazures is quoted as saying; “However, the Jaguar — any mark — was never used as a supersonic aircraft. Only once, one of the prototypes reached Mach 1.06, but that was for contractual reasons. It was in the military requirement so the aircraft needed to prove it could do it, and — with difficulty — it did it!”

He must be referring to prototype E01 which went supersonic on its third flight. But is it true that no Jaguar by any user was ever flown supersonic after this? And if so, the oft quoted Mach 1.1 at SL and Mach 1.6 at 36,000ft must be theoretical calculations only?

 

[red admiral]

Feels unlikely that during air combat manoeuvring with reheat and diving no one ever exceeded the Mach. Similar for low altitude max throttle runs

 

[Archibald]

I'm surprised about this too...

 

[Hood]

After doing some rummaging I think Desmazures may have been liberal with the truth.

Both Jimmy Dell and Bernard Witt flew E-01 supersonically during test flights in September and October 1968.
Paul Millet flew B-08 XW566 and on its maiden flight on 30 August 1971 spent 2 minutes at supersonic speed. One 16 November 1972, the second production GR.1 XX108, and the first with the laser-nose, was flown for the first time and also went supersonic.
Eric Bucklow flew S-07 XW563 performed supersonic performance tests on 26 July 1973 and performed two supersonic gun-firing sorties in GR.1 XX110 on 15 May 1974.

These are just some of the many test sorties carried out by BAC alone.
The bigger question is why Desmazures was so disparaging about the aircraft he helped develop?
Maybe the French never bothered to fly theirs supersonic given they retained the lowered-powered Adour 102s throughout their service?

 

[H_K]

I think the point is that the Jaguar had zero supersonic capability in real world operational conditions. It would have to fly too high, burn too much fuel, carry too little load. There would never be any set of circumstances where the capability would be useful, so it simply wasn’t used in operational squadrons.

Jaguar performance on Mk102 Adours is available here: https://www.avialogs.com/aircraft-s...3100-16-jaguar-aircraft-operating-data-manual

It was supersonic to Mach 1.2-1.3 in clean configuration or with 5 pylons at low weights (<10 tons), which means low fuel (~1.3t) and limited playtime, only above 20-25,000ft and only in favorable ISA conditions. Add a centerline fuel tank or any payload and it wouldn’t go over M1.1 with a huge fuel flow penalty.

 

[Archibald]

I think the point is that the Jaguar had zero supersonic capability in real world operational conditions. It would have to fly too high, burn too much fuel, carry too little load. There would never be any set of circumstances where the capability would be useful, so it simply wasn’t used in operational squadrons.

Jaguar performance on Mk102 Adours is available here: https://www.avialogs.com/aircraft-s...3100-16-jaguar-aircraft-operating-data-manual

It was supersonic to Mach 1.2-1.3 in clean configuration or with 5 pylons at low weights (<10 tons), which means low fuel (~1.3t) and limited playtime, only above 20-25,000ft and only in favorable ISA conditions.

And even less loaded with heavy Martels in ultra-hot Africa climate, for sure.

"Jaguar only manages to takeoff because Earth is round" - favorite running joke of French pilots.

 

[pathology_doc]

I think the point is that the Jaguar had zero supersonic capability in real world operational conditions. It would have to fly too high, burn too much fuel, carry too little load. There would never be any set of circumstances where the capability would be useful, so it simply wasn’t used in operational squadrons.

Jaguar performance on Mk102 Adours is available here: https://www.avialogs.com/aircraft-s...3100-16-jaguar-aircraft-operating-data-manual

It was supersonic to Mach 1.2-1.3 in clean configuration or with 5 pylons at low weights (<10 tons), which means low fuel (~1.3t) and limited playtime, only above 20-25,000ft and only in favorable ISA conditions. Add a centerline fuel tank or any payload and it wouldn’t go over M1.1 with a huge fuel flow penalty.

Similar to the debate over the extent to which the F-105 or the MiG-21 is a Mach 2 airplane. Yes, you can get it there - but for how long and with what degree of practical usefulness?

I can tell you this right now - when I was between the ages of eight and about twelve, glued to any number of combat aircraft books written by Bill Gunston and his contemporaries, I couldn't have cared less. What mattered? Whether the aircraft could actually touch Mach 2 (point whatever) at all was what mattered. High speed makes a schoolboy happy.

The drag penalty of external stores wasn't something my prepubescent mind was either capable or desirous of comprehending or acknowledging. In fact, I don't think that even started registering until my late teens.

My fifty year old mind, today? Now that's another matter.

 

[overscan (PaulMM)]

Supersonic capability was a requirement for the cancelled trainer version which was thought necessary for training future fighter pilots. I dont think it was useful for the strike variant.

 

[Grey Havoc]

I dont think it was useful for the strike variant.

Tactical nukes?

 

[Archibald]

RAF Jaguar pilots get ripped mercilessly, even now, for how slow and underpowered the aircraft were.

Oh really ? even with the mk.106 engines ? imagine the french ones then
...
Made it to 2007 and in Africa with the mk.102s.

 

[Hood]

I agree that operationally supersonic flight was probably very rare, the French A was underpowered and the British GR.1/ GR.1A were often loaded up with all kinds of draggy external pods and weapons and were more in their element at high subsonic speeds at very low altitude (though they did fly CAPs over Bosnia).

But Desmazures comment that only one prototype only ever went supersonic and then only once and struggling to get to Mach 1.06 seems hyperbolic as BAC seems to have tested the single-seat S and two-seat B supersonically numerous times. Indeed I doubt the MoD(PE) would have gone through the deal had it not been able to make its contracted performance to that extent.
I would be surprised if HAL hadn't tested their licence-built Jags at supersonic speeds either.

Perhaps also a lesson to all us historians that even engineers involved can have faulty memories and biases. Just because someone was there doesn't mean they are telling you the whole truth.
So when Desmazures says the cracking on the engine mountings of the Jaguar M was due to a known production fault in the nuts and the test pilot (and many accounts since) say the cracks were due to overstress from catapult launchings and arrester landings who do we believe?

 

[TomcatViP]

Both. If there was cracks, there was a design failure that could have been the result of a faulty part in production (wrong quality standard, wrong material...).

Having grown nearby a Jaguar base, I vividly remind the deafening sound of the jets crossing the sound barrier at low altitude more than once (I would say they were enthusiastically simulated attack runs on the airbase).

 

[Deleted member 2278]

RAF Jaguar pilots get ripped mercilessly, even now, for how slow and underpowered the aircraft were.

Probably not by Harrier drivers though. Lest everyone forget, the Jag served with distinction in the Gulf and the Balkans and went out of service in GR.3 form as quite a capable little beastie.

 

[Archibald]

So when Desmazures says the cracking on the engine mountings of the Jaguar M was due to a known production fault in the nuts and the test pilot (and many accounts since) say the cracks were due to overstress from catapult launchings and arrester landings who do we believe?

Oh please. The crack in the engine bay that eliminated the Jaguar M for good, was confirmed by the French Navy during Foch trials. And it was only the final nail in a very large coffin, that included
- badly underpowered
- the necessary modular reheats then played havoc with the Foch deflectors
(worse than a Crusader J57 AB)
- needs a larger and expensive wing

In final approach to a carrier it was found to be dangerous to fly because it lacked both lift (small wings) thrust (weak engines) while too heavy.

It would have been a death trap, really. Even on much larger carriers.

That's why I often rolled my eyes (at AH.com before those A-holes banned me) when the Jaguar M was presented as "possible naval interceptor" either to replace the French Crusaders or in alt RN carriers scenarios.
- The Jaguar manoeuvered like a brick
- it had no real radar
- it was underpowered
- the naval variants had all the flaws above

The basic idea seems to be "but it was supersonic, unlike the SHAR - so it could chase Backfires more easily".
(facepalm)
...
Chasing Backfires in a naval Jaguar...
...
[insert BAD Red storm rising "dance of vampires" ripoff HERE]

 

[Pioneer]

Well stated sideshowbob9
At the end of the day the Jaguar has proven itself to be a versatile combat aircraft which it's operators appreciated and operated it in the relems of its limits - as any combat aircraft is and has to be.
I guess the once over emphasis in 'supersonic' performance which added size, weight, complexity and cost to designs, which in reality was very rearly used in actual combat or was immediately negated once external drop tanks and armament was add (with the exception on weapons bay designed and equipped aircraft and those designed from the outset to supercruise)
Interestingly, I've lost count of F-111 pilots who when asked 'how would you change the F-111 design, given the chance?' - they so often respond with the elimination of it's Mach 2 speed requirement, which was fundimental to the F-111's design and hence it's complexity....

Regards
Pioneer

 

[Archibald]

Interestingly, I've lost count of F-111 pilots who when asked 'how would you change the F-111 design, given the chance?' - they so often respond with the elimination of it's Mach 2 speed requirement, which was fundimental to the F-111's design and hence it's complexity....

A-6 Intruder maybe ?

Also Buccaneer vs TSR-2 (And F-111K and AVFG).

 

[pathology_doc]

Interestingly, I've lost count of F-111 pilots who when asked 'how would you change the F-111 design, given the chance?' - they so often respond with the elimination of it's Mach 2 speed requirement, which was fundimental to the F-111's design and hence it's complexity....

Probably why the B-1B lost its Mach 2 capability in the shift from short-run semi-prototypes to production bomber in service.

 

[Archibald]

Yes. It makes the air intakes much simpler and in turn dropped the cost - if only marginally.
Same for its low altitude dash speed: mach 1.25, then mach 0.92, then mach 0.85.

 

[Grey Havoc]

Probably why the B-1B lost its Mach 2 capability in the shift from short-run semi-prototypes to production bomber in service.

Not really. The B-1B that we know was from the start intended as a interim, relatively low cost, bomber to help fill the gap until the ATB (B-2) could come online. As part of this, among other things the amount of titanium in the airframe was drastically cut down, with a corresponding decrease in performance and capabilities compared to the B-1A. Of course, the cost overruns on the program, especially on the EW suite, ended up more than wiping out any cost savings that so severely compromising the B-1B was hoped to achieve. And the legacy of this corner cutting has ensured that the Lancer has to be now be retired at a time when it is needed even more than ever, though to be fair those behind procuring the B-1B as a strictly interim type never dreamed in their worse nightmares that it would be in service for so long.

 

[Zoo Tycoon]

I’ve just spoken with a friend who was a Jaguar pilot between 1976-80 and he confirmed it was supersonic rated while in service with the RAF.

Whilst at the OCU all pilots had a standard supersonic handling sortie, with a clean wing whereby a climb to 40kft was followed by a dive up Mach 1.4 at 25kft then recovery. When asked if they ever did this operationally, he said no as all the tasking was low level where they were limited to about Mach 0.95. But he noted if not careful this could be exceeded in level flight but wasn’t sure by how much……. anyone doing this was in test pilot territory. All higher levels sortie focused on maximum transit range so were decidedly subsonic.

 

[Pioneer]

By the end they were carrying around all sorts of extra stuff, nearly always with wing tanks to actually go anywhere.

Really should have been reassessed and upsized from the fast jet trainer it was. Still, the guys got the job done when asked!

By the end they were carrying around all sorts of extra stuff, nearly always with wing tanks to actually go anywhere.

Really should have been reassessed and upsized from the fast jet trainer it was. Still, the guys got the job done when asked!

Good point coanda
I concur.

Regards
Pioneer

 

[Zoo Tycoon]

Probably why the B-1B lost its Mach 2 capability in the shift from short-run semi-prototypes to production bomber in service.

Not really. The B-1B that we know was from the start intended as a interim, relatively low cost, bomber to help fill the gap until the ATB (B-2) could come online. As part of this, among other things the amount of titanium in the airframe was drastically cut down, with a corresponding decrease in performance and capabilities compared to the B-1A.

I’m unsure how much titanium would have really been required in the B1A. Concorde could supercriuse with an aluminium airframe and titanium is really essential above Mach 2.5. Of course being a government contract Rockwell might have been fairly generous with the amount used.

B1A’s flight envelope exploration above Mach 1.3 was halted fairly early in flight test when it was discovered an engine surge would be lead to loss of aircraft. I think the B58 flight testing events were still fresh in everyone’s minds as well. The basic flaw in the design was the intake spill doors exhausted span wise. An engine surge will cause a reverse flow in the engine which I turn will dump an excess of air out off the intake spill doors. Hence during a surge, the spill doors eject high velocity turbulent air spanwise across the lower wing surface thus causing a loss of lift …. on the same side where the thrust had been lost. This leads to an uncommanded roll yaw which will turn the aircraft sideways while supersonic.

Concorde’s intake spill doors faced downwards so if (when) the engine surges, the excess air is ejected downwards hence the lower wing surface is unaffected. Furthermore this actually provides a little up thrust that counters the adverse yaw drag from the engine thrust loss. The FAA test pilots assigned to Concorde, were former B1A guys and initially couldn’t believe a supersonic engine surge could be so benign.

When B1B was proposed, it included a new intake, rotated 90degs for downward spill ejection, but was deemed too expensive. Remember it’s not just the re-engineering of the parts, it’s the whole above Mach 1.3 flight test program hadn’t been preformed, so was needed for release to service. In order to save money the B1B just limited the speed.

 

[TomcatViP]

Titanium is used for the center wing-box, given it's high tensile strength, better ability to sustain load with a temperature rise, good behavior in fatigue a low deformation:

 

[Archibald]

My understanding is: in the case of the B-1A titanium was not needed to go fast (as in the SR-71... with its SOVIET titanium, the ultimate Cold War irony)
It was needed to go low and fast - Mach 1.25 at ground level. On a VG wing aircraft.

Titanium is used for the center wing-box, given it's high tensile strength, better ability to sustain load with a temperature rise, good behavior in fatigue a low deformation

 

[Zoo Tycoon]

Titanium is a great material for a swing wing pivot box irrespective of if the aircraft is supersonic or subsonic;- this component experiences very high concentrated loads/moments going into/out of the lugs. Aluminium would never make the fatigue life and steel would be too heavy.

Where titanium is needed on a supersonic supercriuse aircraft is in the highly loaded kinetic hot zones such as the wing leading edge. One of the issues with using titanium is that it’s difficult to integrate it with other metals due to thermal expansion matching, tribological compatibility and other structural issues. Hence if you need a titanium leading edge to hack the heat-n-loads, although the rest of the wing maybe within the range of aluminium, the simplest solution is to just make the whole wing from the stuff. In my experience, Titanium is painful to use as it has the ability to show an unheard of & unexpected problem in every new application.

 

[Archibald]

"4000 missiles were fired at SR-71s, none ever hit"
Urban legend, but there is more.

"4000 missiles were fired at SR-71s by Soviets who were unaware they were shooting at their own titanium speeding over their heads". LMAO

And this is not an urban legend. US titanium quality frustrated Lockheed: it wasn't good enough. Enter the CIA "better titanium is available in the Soviet Union... and yes, we will procure enough of it." And so they did.

This is so absurd when you think about it...

 

[pathology_doc]

"4000 missiles were fired at SR-71s, none ever hit"
Urban legend, but there is more.

"4000 missiles were fired at SR-71s by Soviets who were unaware they were shooting at their own titanium speeding over their heads". LMAO

And this is not an urban legend. US titanium quality frustrated Lockheed: it wasn't good enough. Enter the CIA "better titanium is available in the Soviet Union... and yes, we will procure enough of it." And so they did.

This is so absurd when you think about it...

It gets better. Much of the armour that the British put into their cruisers just before World War 2 came from German foundries, delivered in part by German railways. In this case, the driver was the inability to produce enough high quality armour with sufficient speed. (Source: D K Brown; Nelson to Vanguard.)

 

[Scott Kenny]

Titanium is a great material for a swing wing pivot box irrespective of if the aircraft is supersonic or subsonic;- this component experiences very high concentrated loads/moments going into/out of the lugs. Aluminium would never make the fatigue life and steel would be too heavy.

Where titanium is needed on a supersonic supercriuse aircraft is in the highly loaded kinetic hot zones such as the wing leading edge. One of the issues with using titanium is that it’s difficult to integrate it with other metals due to thermal expansion matching, tribological compatibility and other structural issues. Hence if you need a titanium leading edge to hack the heat-n-loads, although the rest of the wing maybe within the range of aluminium, the simplest solution is to just make the whole wing from the stuff. In my experience, Titanium is painful to use as it has the ability to show an unheard of & unexpected problem in every new application.

Titanium dust/shavings likes to catch on fire at little provocation, too. And the stuff burns blinding white, as bad or worse than magnesium. Sparks from grinding titanium are also blinding white. I'm talking "wear acetylene welding goggles while grinding titanium" bright.