Was the Spey-engined `toom a hot-rod?
...a race....
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.
Last edited by Minnie Burner; 24th Apr 2016 at 09:24.
Originally Posted by Minnie Burner
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.
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.
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.
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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.
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.
They were rocket ships of their day.
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F4 thrust
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
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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.
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Where the Spey lost out against the 79 was at high super sonic as the ramps were not programmed.
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
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
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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.
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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.
