Was the Spey-engined `toom a hot-rod?

[tartare]

Reading the Wikipedia entry - it seems to suggest that although there was a considerable amount of modification required, the Spey-engined Phantom exceeded the GE-engined US jet in performance in almost all arenas but flight at altitude.
Is that right?
How did those of you who flew it find it?
Did anyone have a chance to fly both the US engined jet - and the Spey engined jet to compare?
I suspect so - given training requirements - which I assume took place in the US before the first jets were delivered?
Would be very interesting to hear some stories...

[Background Noise]

Plenty over here flew both - 74 Sqn's post-Falklands aircraft were ex US Navy F4Js.

[Dan Gerous]

I read in a book somewhere that the Brit Tooms were more expensive and underpowered, compared the American engined examples.

[Rhino power]

I read in a book somewhere that the Brit Tooms were more expensive and underpowered, compared the American engined examples.

Underpowered? No...

Spey - 12,250lbs dry, 20,515lbs reheat
J79 (GE-17) - 11,900lbs dry, 17,900lbs reheat

Unfortunately, the fuselage mods to allow the Spey to fit (wider intakes needed for increased mass air flow, deeper and wider rear fuselage) ruined the area ruling and increased drag to such an extent that much of the expected benefits of the increased thrust of the Spey were lost.

-RP

[27mm]

I only flew the FGR2 / F4M, but it was no slouch. In RAFG LLAD fit (2 bags + gunpod), we made 1.6M at 36K on one high level intercept as fighter; my WSO was not a happy bunny, as it screwed his final turn keys.

At LL in the above config, she was superb, with awesome acceleration. With tanks and gunpod removed she was brutally powerful. On a windy winter's day, I recall being airborne just past the app end cable, after an 8 second ground roll; this just about matches the Tiff!

In my book she was a great fighter.

[Ali Qadoo]

Like 27mm, I was an FG1/FGR2 man, but I remember that we did a number of mixed type trips from Wattisham and our FGR2s had a job keeping up with the 74 Sqn aircraft.

[Tailspin Turtle]

In McDonnell flight test in 1967, our tired F-4C chase plane had no problem keeping up with the first F-4K during acceleration at altitude. We (and Rolls-Royce) were relieved when it finally reached Mach 2. The Brits blamed the shortcoming on airframe drag and McAir, less than spec thrust. Performance may have improved subsequently.

[LowObservable]

It may have been Gunston or Roy Braybrook who wrote that "nobody realized how much supersonic thrust the J79 could put out, until they put the Spey in the F-4".

[LOMCEVAK]

The Spey did have very good thrust at low level but the reheat light-up time was quite slow (about 5 seconds from memory). I flew one trial in 'C' fit when we had tests at 750 KIAS (the limit)and 250 ft (over the sea) and thrust was not a problem. I only flew a few sorties with the J79 and didn't have the chance to go high speed low level so cannot comment on the difference.

At Boscombe we had the pre-series F-4K (XT597) which we often flew clean (plus AIM7 on station 6 for c.g. reasons) and it was quite light so the opportunity was taken to try to get a Spey-engined F-4 to 2.0M. The profile we used was to climb to 48 000 ft at 0.95M then enter a shallow dive to accelerate until you reached 2.0M. The first time I tried it the rate of climb seemed quite low above 40 000 ft so I started the dive before early (cannot remember precisely how high) and I only reached 1.95M. The next time I persevered to 48 000 ft and reached 2.0M quite easily. We had a couple of very experienced F4 guys on the squadron and they had never been to 2.0M in a Spey-engined aircraft until they flew 597. Again, I never had the opportunity to fly this profile in a J79 mark so cannot compare although the high altitude flying that I did in one I recall as being much better performance qualitatively. The only other interesting performance point in a 'clean' 597 was 600 KIAS at low level, pull into a vertical climb and zoom until about 250 KIAS then pull over at 5 - 10 AOA until inverted and roll out; used to make about 31 000 ft. Happy days!

[MPN11]

Clean aircraft generate impressive numbers, those in war-fighting don't.

I recall the 20 Sqn Hunters from Tengah, going to to Seletar for a major service. There was a roster! Tanks, pylons and, IIRC, even the Sabrinas were taken off. A clean Mk 9 ... Anyone here with a 20 minute trip in a stripped-down Hunter before fuel became a bit 'interesting'? :)

I was 20 Sqn's ATCO, so they told me these things. I only ever got to fly in the NoMotion Sim ... dammit :)

[Background Noise]

I imagine the Spey, designed for the Bucc with a small by-pass, was optimised for low levels. More thrust off the boat and better range at all levels, but less thrust at high level (a trait the F3 inherited) - and also for the drag reasons highlighted above. I guess the J79, like many US engines would have had much quicker response and been better at high level.

I've flown in a couple of US-engined jets, including a German F4 once, and I seem to remember the rpm gauge seemed to be connected directly to the throttle - unlike the laggy response of UK high by pass jets.

[Dan Gerous]

Underpowered? No...

Spey - 12,250lbs dry, 20,515lbs reheat
J79 (GE-17) - 11,900lbs dry, 17,900lbs reheat

Unfortunately, the fuselage mods to allow the Spey to fit (wider intakes needed for increased mass air flow, deeper and wider rear fuselage) ruined the area ruling and increased drag to such an extent that much of the expected benefits of the increased thrust of the Spey were lost.

-RP


Of course I should have said slower, thanks for that Rhino. I take it from your moniker, you're a fan of the Mighty Toom as well.

[Rhino power]

I take it from your moniker, you're a fan of the Mighty Toom as well.

'fan', might be considered something of an understatement, 'obsessive' is probably closer to the truth... ;)

-RP

[walbut]

One aspect where the Spey was outperformed by the J79 was the reheat nozzle design. The translating shroud on the Spey had a large base area behind the inner petals so even when the nozzle was fully open in max reheat there was still a lot of base drag. There was talk of a true convergent/divergent nozzle being designed for the Spey but as far as I know it never materialised.

I recently re-read Sir Stanley Hooker's autobiography Not Much of an Engineer. In one chapter he describes his experiences when Rolls Royce sold the Spey 202 design to the Chinese. In the mid 1970's we (HSA Ltd) hosted a visit to Holme on Spalding Moor by a combined Rolls Royce and Chinese delegation. We had been told they could see any aspect of the engine and it's installation in a UK Phantom but not view the radar or look in the cockpit. I expected lots of detailed questions about the clever bits of the installation such as the intake ramps and bell-mouth. In fact the thing that seemed to excite the Chinese the most were the little spring-loaded fingers that sealed the gap between the rear fuselage and the translating reheat shroud. I have occasionally wondered how they got on with the reheated Spey and whether they are still in service.

Walbut

[gzornenplatz]

Having spent 15 years flying both, one snippet might help. The Avengers, flying F5s reckoned that when they did a head-on pass against an F4K/M it had accelerated out of Sidewinder range by the time it was in their gunsight, unlike the J79 F4, which was still in range.

[RetiredF4]

Let me add the supersonic test profile of the German J- 79 RF-4E, clean aircraft.
We climbed to 36.000 ft , selected reheat and accelerated through mach1 in a slight dive, regained FL 360 and accelerated level to check at least M2.2 as max speed , which some jets exceeded up to M 2.35. To reduce to subsonic speed the power had to be reduced to minimum reheat ( deselecting reheat could have blown the nozzle flaps), spedbrakes were extended and a zoom climb to 48.000 feet initiated. AFAIK the German J-79 F-4F was doing the same profile, but was slower in top speed.

[Rhino power]

I have occasionally wondered how they got on with the reheated Spey and whether they are still in service.

Walbut

License built copies of the Spey 202 (Xian WS-9) are still in service and power the Xian JH-7/7A...

-RP

[BBadanov]

The Chinese had a lot of trouble producing the Spey 202 as the WS9.

Even though it was under licence production from RR, they didn't have the level of technology for - at that stage - such an advanced afterburnered bypass. A main problem, I believe, was mastering turbine blade technology.

So in a game of catch-up there was a lot of reverse-engineering, and in the late 1990s China bought over 100 ex-RAF F-4 Speys. These powered the initial limited batch productions of the JH-7 (FB-7).


Finally they cracked it with the indigenous WS9A which has powered the follow-on JH-7A. China has truly benefited from the technology transfer.

[ancientaviator62]

A very good read on the early problems with the Spey engined F4 is 'Fly no more' by Brian Davies.

[sfm818]

Scan2334%255B5%255D.jpg (image) (http://lh3.ggpht.com/-y0gYtXSo8o4/VFaa6PicWkI/AAAAAAAAC_I/DjzrWTSC6pc/s1600-h/Scan2334%25255B5%25255D.jpg)

Would be interested to know if the Spey fit contributed to wing crack issues on the K & M.

[just another jocky]

In a GR1 on an oversea mission on TLP years ago, I arranged to have a race with a German F4.....nothing in it.

[Minnie Burner]

...a race....How enlightening. Thank you.


As for the wing cracks, perhaps this leads to a question about operating weights and environments, more than the Spey mods specifically.

I remember the Spey reheat being tough to light at 'moderate' altitude on 'RAFG, standard NATO' fuel unless you were at high subsonic Mach. The resulting fuel stream was a distinct embarrassment.

[just another jocky]

How enlightening. Thank you.


Due to the nature of this medium, your meaning could be taken different ways. Sarcastic or genuine. I will choose genuine.


It was what it was.

[typerated]

JaJ


What height, start speed, distance etc?


I would have thought you would have had him down on the deck though?

[just another jocky]

On the deck oversea.


Not sure of his fit but we were small tanks, outboard ECM. I vaguely recall we both slowed to around 300kts then on a head nod (we were quite close) hit the reheat. Both slowed somewhere north of 600kts before we went s/s. This was a GR1 with 103 engines.


Only took a few seconds so couldn't have been more than a few miles.

[engineer(retard)]

I've got a fuzzy memory of hearing that the single engine performance in the Spey powered version was better but it was along time ago.

[KenV]

My understanding was that the two-spool turbofan Spey (vs the single spool turbojet J79) produced more thrust at low speed and low altitude for improved take off from the smallish RN carriers, and provided more bleed air for the Phantom's boundary layer control system for improved landing speed onto the smaller carriers. But the higher airflow required increasing the intake area 20% and a pretty drastic redesign of the aft fuselage. These combined to slightly increase form drag (which was more than overcome by the increased thrust) and significantly increased wave drag while reducing intake recovery at high mach (over 1.6) which resulted in a lower top speed. But the Spey's biggest contribution was significantly improved fuel consumption. If memory serves about 15% improvement in combat radius and nearly 20% in ferry range, pretty impressive considering that form drag had gone up.

[Courtney Mil]

The simple answer to the OP's question is, "Yes". It was. And so were the J-79 powered F-4s. It's an old argument and, short of restating all yet again, the difference in bypass and frontal cross section gave each type advantages in different regimes. Worth arguing about? No, not really.

They were rocket ships of their day.

[Tinribs]

I was at Aldergrove, 23 MU, where the F4s were overhauled. I was the Canberra TP and Bill Freeman was the Phantom boy. He always said the Spey job was vastly better on take off and early climb but not much in it later. My v few F4 trips did not allow any sensible opinion

[Blaenffynnon]

Where the Spey lost out against the 79 was at high super sonic as the ramps were not programmed. Against the f14, it used its standard defence against the F4 and went straight up,roling in behind when the 79 f4 fell out. Unfortunately for the F14 the Spey F4 was hanging there with it. Oh yes and the Spey did not smoke.

[Blaenffynnon]

There never seemed to be any lack when taking a wave off or that rare event a bolter,

[NutherA2]

Where the Spey lost out against the 79 was at high super sonic as the ramps were not programmed.

I don't know where this misunderstanding comes from; the FG1 ramps (I never flew the FGR2) certainly were. IIRC they started to move as we accelerated through Mach 1.4

[walbut]

The Spey engined Phantom ramps were definitely programmed, if I remember rightly to a schedule dependent on total air temperature. I can remember investigating several ramp servo valve failures. The cap head screws that held the covers over the end of the spool valves used to fail, probably because of pressure fluctuations in the hydraulic system, or it may have been a batch of duff screws, my memory fails me on that.

In the early days there were lots of hydraulic pipe failures which we investigated at HOSM. Initially we did it by calibrated feel by hand during during ground runs. Later using pressure transducers and accelerometers we found the pipes were vibrating in tune with a pressure ripple from the engine driven pumps. This was as a result of McDonnell Douglas changing the length of the hoses between the engine mounted pumps and the airframe, as a consequence of fitting the Spey in place of the J79. We fitted a small spherical capacity absorber in the end of the affected pressure hoses and it significantly reduced the amplitude of the pressure ripple and the pipe failure rate.

I remember a story, possibly apocryphal that on one of the Phantom bases the engineering officer got fed up of repeated pipe failures and was convinced his riggers did not know how to make and fit hydraulic pipes. He therefore gave them a demonstration and made and fitted a pipe himself. It failed on the next flight.

Walbut

[tarantonight]

I sense you have some stories to tell Blaenffynnon................

[tarantonight]

Good stories..................

[Blaenffynnon]

I don't know where this misunderstanding comes from; the FG1 ramps (I never flew the FGR2) certainly were. IIRC they started to move as we accelerated through Mach 1.4

It was a long while ago. I will have to have a look at my PN's.

[johnwill]

Underpowered? No...

Spey - 12,250lbs dry, 20,515lbs reheat
J79 (GE-17) - 11,900lbs dry, 17,900lbs reheat


-RP

My first post on pprune, so please bear with me. Unfortunately, those thrust figures can be misleading, as they are uninstalled, sea level static values. Installed thrust, at the flight condition of interest is what matters. The Spey, by its very nature of bypass, has a lower exhaust velocity than the pure jet J-79, so produces less thrust than the J-79 at higher true airspeeds. But you know that already.

Let me cite another example. In the early days of F-16 development, a one-off lower cost version was tried. In place of the 23,800 lb thrust P&W F100 turbofan, a 17,900 lb thrust J-79 was installed. Like the Spey-powered F-4, it also had a revised inlet to match airflow requirements. Here again, the J-79 proved to have a higher maximum speed, easily reaching 2.05 mach, while the standard airplane struggled to hit 2.0. The J-79 had more available, but prudence and politics held it back.

[johnwill]

Having spent 15 years flying both, one snippet might help. The Avengers, flying F5s reckoned that when they did a head-on pass against an F4K/M it had accelerated out of Sidewinder range by the time it was in their gunsight, unlike the J79 F4, which was still in range.

The hotter J-79 exhaust might have been a factor in extending the detection range of the Sidewinder.

[Minnie Burner]

Ref Post #34/35
Already told:
http://pictures.abebooks.com/isbn/9780850527322-us.jpg

ISBN 10: 0850527325

[Rosevidney1]

The saga was extremely well recorded by Lt/Cdr Brian Davies in his fascinating book 'Fly No More'.

[tarantonight]

Read both above. Very good. There is something slightly comforting reading yarns of steering a Sea Vixen around the South China sea in the pitch black whilst in the warmth of my house!!

[Blaenffynnon]

It was a long while ago. I will have to have a look at my PN's.

Sorry to take so long in replying. What I should have said in the first case was that I don't think the ramp s/w was updated for the Spey F4 as most RN sorties involved tanks of some description which limited speed to 1.8 max

[Rhino power]

The FG.1 AP101 suggests the possibility of a compressor surge if the ramps are in the retracted position at speeds above M1.5, so they're obviously scheduled to move at speeds well below M1.8...

-RP

[walbut]

I have had a look at an F4B flight manual and an FG 1 manual on the web - its surprising what's out there. The F4B manual says the variable ramp starts to move at a TOAT of +45 deg C and is fully extended to an angle of 14 degrees at a TOAT of +146 deg C. Assuming a static OAT of -40 deg C, typical of 40,000 ft, the ramps will start to move at Mach 1.4.

The FG Mk 1 flight manual does not quote the schedule but says the variable ramp moves 16 degrees so there must be some differences between J79 and Spey engined aircraft. There would be no software involved back in the 1960s, I am sure it would all have been analogue electronics.

For those of you wondering about the purpose of the ramps, their role in life is to create a pair of oblique shockwaves across the front of the intake, one originating at the front of the fixed ramp and the second at the front of the variable ramp. A final normal shockwave originating at the back edge of the variable ramp slows the air down to subsonic speed. By progressively reducing the speed of the air in a series of steps, rather than one big jump through a normal shock, the pressure recovery of the intake, and the overall system efficiency is maximised. Of course its actually the aircraft that's moving supersonically, not the air, but its all relative, as Albert Einstein said (I think)

Walbut