Lighting Engine Intake technology
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Lighting Engine Intake technology
Lighting Engine Intake Technology
Back in 68 on 29 Sqdn at Wattisham and was a J/T AI23b fixer, but being a thin chap at the time I also got the Job of having to do preliminary intake internal inspection after small bird strikes to decide if we needed to pull the bullet for a more detailed inspection. Always hot and full of fumes particularly when having to take a look at the top engine that was set further back. (You made sure you had your best mate outside and another to keep people out of the cockpit.)
However I have always wondered how the intake technology worked.
The Lighting AI23b bullet is fixed in place, so how was the intake airflow managed for 175knts to M2.2.
The Mig 21 radar bullet moves back and forth as I believe so does the SR71 intake bullets.
Mechanics of flight (AC Kermode ) and Ap 3456 vol 2 only talk of ramps and Isentropic intakes. So How did the Lighting intake work?
This has been bugging me for years and i do need to get a life.
One point though my log book shows the following;-
20/8/68 Lighting T5 – Z F/O Abbott RAF Wattisham Local 1700-1735 M1.3 at 25000ft to 40000 ft and the Vulcan turned inside us.
Cheers Orion
Back in 68 on 29 Sqdn at Wattisham and was a J/T AI23b fixer, but being a thin chap at the time I also got the Job of having to do preliminary intake internal inspection after small bird strikes to decide if we needed to pull the bullet for a more detailed inspection. Always hot and full of fumes particularly when having to take a look at the top engine that was set further back. (You made sure you had your best mate outside and another to keep people out of the cockpit.)
However I have always wondered how the intake technology worked.
The Lighting AI23b bullet is fixed in place, so how was the intake airflow managed for 175knts to M2.2.
The Mig 21 radar bullet moves back and forth as I believe so does the SR71 intake bullets.
Mechanics of flight (AC Kermode ) and Ap 3456 vol 2 only talk of ramps and Isentropic intakes. So How did the Lighting intake work?
This has been bugging me for years and i do need to get a life.
One point though my log book shows the following;-
20/8/68 Lighting T5 – Z F/O Abbott RAF Wattisham Local 1700-1735 M1.3 at 25000ft to 40000 ft and the Vulcan turned inside us.
Cheers Orion
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I remember reading a book a while back that (as I recall) talked briefly about the Lightning intake. The author described the intake aerodynamics as (my words) shockwave hell or something similar. I believe at migh MF the shockwaves were all over the shop and reduced the pressure recovery et al but the engines still managed to thrunge out enough splergs to get it shifting like excrement off an earth lifting device.
I can picture the guy who wrote it (brown beard, 50 ish) and I know he lectures at RMCS but I can't for the life of me remember his name or the books name - any budding TP candidates would prolly know the name as it is (or at least was) part of the pre-selection reding reading list.
MT
......Ray Whitford!!!!!!!!!
I knew it would come to me :-)
The name of the book will probably come to me at 0300L tomorrow morning.......
I can picture the guy who wrote it (brown beard, 50 ish) and I know he lectures at RMCS but I can't for the life of me remember his name or the books name - any budding TP candidates would prolly know the name as it is (or at least was) part of the pre-selection reding reading list.
MT
......Ray Whitford!!!!!!!!!
I knew it would come to me :-)
The name of the book will probably come to me at 0300L tomorrow morning.......
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The Lightning Intake was optimised to be at it's most efficient at Mach 1.3. At that speed, the normal shock, ie the narrow band where the air went from supersonic to subsonic, went from the tip of the bullet to rest on the edge of the intake.
As for flying with Abbo--should have flown with someone who could pull more G!!
As for flying with Abbo--should have flown with someone who could pull more G!!
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The Avons in the Lightning are fed by a multi-shock intake. As Firestreak describes, the nose acted like a simple pitot intake in the transonic region. A fairly good example of a pitot intake is the nose of the MiG-19. As the aircraft accelerates into a truly supersonic flight regime, the normal shock will begin to break down and the centre body will come into its own.
Those clever chappies at E.E. designed the centre body with a particular curve on it. When the supersonic air hits the front of the centre body it generates an oblique shock. The shock takes some energy out of the flow (slows it down). Behind this, there may be another shock and another behind that, the aim of the game being to slow the intake air down enough for the engines to breathe. Ultimately the designer wants a normal shock standing in front of the engine interface plane: The airflow behind a normal shock is always subsonic.
I think in the Lightning that this normal shock stands between the centre body and the intake walls.
I can’t believe you had to go down a warm intake! Aren’t the fumes hazardous?
Those clever chappies at E.E. designed the centre body with a particular curve on it. When the supersonic air hits the front of the centre body it generates an oblique shock. The shock takes some energy out of the flow (slows it down). Behind this, there may be another shock and another behind that, the aim of the game being to slow the intake air down enough for the engines to breathe. Ultimately the designer wants a normal shock standing in front of the engine interface plane: The airflow behind a normal shock is always subsonic.
I think in the Lightning that this normal shock stands between the centre body and the intake walls.
I can’t believe you had to go down a warm intake! Aren’t the fumes hazardous?
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I think the actual question has been pretty well covered above (at least brings back disturbing memories of Aerothermodynamics!), but in reference to the Whitford book - I believe it is called 'Design For Air Combat' and not the lesser 'Fundamentals of Fighter Design'. If anyone has a copy of the former they want to part with, get in touch.
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Thanks Chaps
--- MobiusTrip and Right Stuff
Did some digging on Amazon and came up with:-
---- Design for Air Combat [Hardcover] by Whitford, Ray
ASIN: 0710604262 ----
I have placed a search order for it, they might or might not find a copy.
Noisy
--------I can’t believe you had to go down a warm intake! Aren’t the fumes hazardous?---------
The fumes did not bother me that much though not pleasant, it was the sound of somebody thumping around in the cockpit that was the major concern, hence 2 mates, one at intake the other at the foot of the ladder.
Also it was only done for very small birds when the damage was not directly apparent. Seagulls and the like made such a mess that the hangar was the only choice. On one inspection I found traces of blood and feathers on the intake wall but saw nothing on the turbine blades. Don’t remember what the Engine blokes did after that.
The other thing that scared the pants off me was a Top engine starter motor blowing up sending out sheets of flame and bits of metal, setting fire to the vented fuel on the port wing.-------
-------- Happy Noisy days------
--- MobiusTrip and Right Stuff
Did some digging on Amazon and came up with:-
---- Design for Air Combat [Hardcover] by Whitford, Ray
ASIN: 0710604262 ----
I have placed a search order for it, they might or might not find a copy.
Noisy
--------I can’t believe you had to go down a warm intake! Aren’t the fumes hazardous?---------
The fumes did not bother me that much though not pleasant, it was the sound of somebody thumping around in the cockpit that was the major concern, hence 2 mates, one at intake the other at the foot of the ladder.
Also it was only done for very small birds when the damage was not directly apparent. Seagulls and the like made such a mess that the hangar was the only choice. On one inspection I found traces of blood and feathers on the intake wall but saw nothing on the turbine blades. Don’t remember what the Engine blokes did after that.
The other thing that scared the pants off me was a Top engine starter motor blowing up sending out sheets of flame and bits of metal, setting fire to the vented fuel on the port wing.-------
-------- Happy Noisy days------
Firestreak is quite right, the Lightning intake was optimised for M 1.3. That's the reason why, on a good day, in the right version of the aircraft you could cruise supersonically in cold power, the engine and intake were working at max efficiency.
Reminds me of a quote I heard many years ago. When the F16 was just the YF16, the US put on a road show comparing the YF16 with an F4, put both aircraft into the air to compare tuning radius etc. I was at Bentwaters when this show came to the UK. Talking to the F16 driver someone mentioned that the flat intake with no centrebody or ramps must be very inefficient---the reply "Sh*t man, we got so much thrust who needs efficiency"
Reminds me of a quote I heard many years ago. When the F16 was just the YF16, the US put on a road show comparing the YF16 with an F4, put both aircraft into the air to compare tuning radius etc. I was at Bentwaters when this show came to the UK. Talking to the F16 driver someone mentioned that the flat intake with no centrebody or ramps must be very inefficient---the reply "Sh*t man, we got so much thrust who needs efficiency"
