Future Carrier (Including Costs)
Right, NaB, there was no consideration of a twin for STOVL.
We can't make a STOVL that can land engine-out - aircraft T/W in V-mode is marginal as it is - and engine failure in V mode would still be catastrophic in any conceivable layout with rapid divergence outside the safe ejection envelope.
Result: twin STOVL is (even) less safe than single STOVL. So F-35 gets a brand-new, very large engine, and since engine T/W tends to decline with size, and it has an oversized LPT to drive the fan, it is a heavy and complicated engine.
We can't make a STOVL that can land engine-out - aircraft T/W in V-mode is marginal as it is - and engine failure in V mode would still be catastrophic in any conceivable layout with rapid divergence outside the safe ejection envelope.
Result: twin STOVL is (even) less safe than single STOVL. So F-35 gets a brand-new, very large engine, and since engine T/W tends to decline with size, and it has an oversized LPT to drive the fan, it is a heavy and complicated engine.
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If the requirement for the JSF had not included STOVL, then the aircraft would have looked completely different ...
Why completely different? Can you state any reasons?
... and may well have been twin-engined.
No. The primary requirement for the F-35 is to replace the F-16. Count the power plants on an F-16.
The primary reason for one engine instead of two in a smaller fighter aircraft, assuming a large single engine can produce the same thrust as two smaller ones, is that the large single will yield better specific fuel consumption, lighter weight, and lower cost.
Consider the trend in civilian airliners: very large twins replacing aircraft with three or four motors. The same considerations are at work in both cases.
Why completely different? Can you state any reasons?
... and may well have been twin-engined.
No. The primary requirement for the F-35 is to replace the F-16. Count the power plants on an F-16.
The primary reason for one engine instead of two in a smaller fighter aircraft, assuming a large single engine can produce the same thrust as two smaller ones, is that the large single will yield better specific fuel consumption, lighter weight, and lower cost.
Consider the trend in civilian airliners: very large twins replacing aircraft with three or four motors. The same considerations are at work in both cases.
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... but as you point out, multi-engine STOVL could never work, ergo, we're stuck with it.
Oh, I think multi-engine STOVL could work. Isn't a V-22 multi-engine STOVL?
My point was that the starting point for the F-35 was to design a successor to the F-16.
Twin engine STOVL fighter-bomber: two F-35 engines in a high wing configuration, with driveshaft over the weapons bay connecting and harmonizing the two engines. ... Similar to the V-22.
Oh, I think multi-engine STOVL could work. Isn't a V-22 multi-engine STOVL?
My point was that the starting point for the F-35 was to design a successor to the F-16.
Twin engine STOVL fighter-bomber: two F-35 engines in a high wing configuration, with driveshaft over the weapons bay connecting and harmonizing the two engines. ... Similar to the V-22.
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VTOL... correction... S/TORVL is not the answer. Interesting to note how JCA was originally pitched to operate from the deck of an Invincible Class Helicopter Landing Deck. That detail is conveniently airbrushed from the official history now that we’re building two 65,000 tonne strike carriers. Added weight and complexities on F-35B will not be appreciated by the first pilot forced to eject from their $136 million stealth fighter due to mechanical/ engine failure.
Even the F-35A is fitted with a hook for low speed arrests, however, in the F-35B the option will be to press a button and the Lift System will do the rest. There are worrying reports that in order to save weight (and due to a lack of space in the airframe) LM will not be fitting fire bottles on the F-35B. Remember how that concept (zero fire suppression systems) turned out for the F-4K/M.
This program bears the hallmarks of a classic procurement lash up. Can we at least make mistakes in a good direction and go with the Carrier Variant which offers better range/ payload.
Now that BAE have cut metal on the first of three flight test airframes, this is a good opportunity to ask how many test airframes has Italy committed to build? and also to mention the fact that Britain has committed twice as much funding as the nearest foreign partner on the JSF program. On what basis was the F-35 European production line given to Italy?
Even the F-35A is fitted with a hook for low speed arrests, however, in the F-35B the option will be to press a button and the Lift System will do the rest. There are worrying reports that in order to save weight (and due to a lack of space in the airframe) LM will not be fitting fire bottles on the F-35B. Remember how that concept (zero fire suppression systems) turned out for the F-4K/M.
This program bears the hallmarks of a classic procurement lash up. Can we at least make mistakes in a good direction and go with the Carrier Variant which offers better range/ payload.
Now that BAE have cut metal on the first of three flight test airframes, this is a good opportunity to ask how many test airframes has Italy committed to build? and also to mention the fact that Britain has committed twice as much funding as the nearest foreign partner on the JSF program. On what basis was the F-35 European production line given to Italy?
ME
I knew someone would mention the mundungous that is V22! Can't quite see how you'd x-connect jetblast though.
Bucc
The FCBA as was (now JCA) was ruled out of CVS ops about 12 years ago, when it became clear just what the size and weight of the a/c was likely to be and what mods to the ship would be required. Round about then, the CVS SLEP option effectively died, although Ali Baghei was forced to include it in his various business case submissions, much against his will and against his vehement objections!
The B is still the nominal option AFAIK, although the tricks being played to meet the bring-back requirement (Rolling Vertical Landings) are far from press the button and let the lift fan do the rest. I believe there's an element of standing on the brakes and praying at some point during the procedure......
I knew someone would mention the mundungous that is V22! Can't quite see how you'd x-connect jetblast though.
Bucc
The FCBA as was (now JCA) was ruled out of CVS ops about 12 years ago, when it became clear just what the size and weight of the a/c was likely to be and what mods to the ship would be required. Round about then, the CVS SLEP option effectively died, although Ali Baghei was forced to include it in his various business case submissions, much against his will and against his vehement objections!
The B is still the nominal option AFAIK, although the tricks being played to meet the bring-back requirement (Rolling Vertical Landings) are far from press the button and let the lift fan do the rest. I believe there's an element of standing on the brakes and praying at some point during the procedure......
GOLF BRAVO ZULU
In order to store enough energy using compressed air would require a vast storage receptacle for the stuff. Steam contains much more energy for a given volume.
It's also usual to partly fill the steam accumulator with superheated water. As the steam pressure drops during the launch, more steam flashes off the water and gives a smoother push towards the end of the catapult travel.
In order to store enough energy using compressed air would require a vast storage receptacle for the stuff. Steam contains much more energy for a given volume.
It's also usual to partly fill the steam accumulator with superheated water. As the steam pressure drops during the launch, more steam flashes off the water and gives a smoother push towards the end of the catapult travel.
I may have missed it but what consideration has been given to the vital question of AEW? Although I understand that the current Seaking is an excellent AEW system the limited range of the airframe means that it will always be too close to the carrier. Surely this means that a fixed wing option will be necessary. What deck requirements would any such option require?
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During the RN v RAF arguments about the P1154 ( which was the big idea for a VSTOL project in the 1960's before fortunately being dropped, the ' preliminary concept test aircraft' P1127 being developed as Plan B, becoming the Harrier ) the Navy pushed for twin engines, citing safety.
Technology then made a safe single engine landing dubious at best, with horrifyingly complex engineering, thus rogering the P1154.
I know John Farley, who had a motto on his desk along the lines of ' the greatest elegance in design is simplicity ' or something on those lines, has said that rule can be safely be overcome ( obviously to an extent only ) with modern technology such as the VAAC Harrier and F-35B.
I of course can't speak for him, but the idea of F-35 with twin engines and various linkages sent a shudder through me !
OK so conventional aircraft may manage a single engine landing ( assuming they started off with more ) and an engine failure during a VL is jolly bad news - I understand the F-35 will have an auto-eject set-up; it might do more than scuff the deck a bit - let's face it, the F-35B is happening, and money will be thrown at it until it's right.
The STOVL arguments seem to forget the useful option of operating from Forward Operating Bases...
I suspect RVL's will not be the nightmare some people make out ( compare it to a Phantom or similar trapping ) !
When the P1127 began, it could barely hover with all unnecessary kit removed; engine development saw it grow into a useful weapon system, and I think the same will happen with the F-35.
As for the V-22, well it seems useful, but I still go by ' if it looks right it is right ' so my toes curl whenever I see one !
Technology then made a safe single engine landing dubious at best, with horrifyingly complex engineering, thus rogering the P1154.
I know John Farley, who had a motto on his desk along the lines of ' the greatest elegance in design is simplicity ' or something on those lines, has said that rule can be safely be overcome ( obviously to an extent only ) with modern technology such as the VAAC Harrier and F-35B.
I of course can't speak for him, but the idea of F-35 with twin engines and various linkages sent a shudder through me !
OK so conventional aircraft may manage a single engine landing ( assuming they started off with more ) and an engine failure during a VL is jolly bad news - I understand the F-35 will have an auto-eject set-up; it might do more than scuff the deck a bit - let's face it, the F-35B is happening, and money will be thrown at it until it's right.
The STOVL arguments seem to forget the useful option of operating from Forward Operating Bases...
I suspect RVL's will not be the nightmare some people make out ( compare it to a Phantom or similar trapping ) !
When the P1127 began, it could barely hover with all unnecessary kit removed; engine development saw it grow into a useful weapon system, and I think the same will happen with the F-35.
As for the V-22, well it seems useful, but I still go by ' if it looks right it is right ' so my toes curl whenever I see one !
Last edited by Double Zero; 7th Apr 2010 at 13:04.
"The primary reason for one engine instead of two in a smaller fighter aircraft, assuming a large single engine can produce the same thrust as two smaller ones, is that the large single will yield better specific fuel consumption, lighter weight, and lower cost."
Lighter weight? Hmph. The reported T/W of the F135 is not as good as the F414/EJ200. Fuel consumption? Sometimes big engines retain performance better, true.
But there's also a lot to be said for the configuration advantages of a twin, with a natural spine for structural loads and system runs, that's also protected by the engines. Brackets and pipes &c to carry the system runs around that vast engine tunnel were ID'd as the source of a lot of the weight problems on JSF.
Lighter weight? Hmph. The reported T/W of the F135 is not as good as the F414/EJ200. Fuel consumption? Sometimes big engines retain performance better, true.
But there's also a lot to be said for the configuration advantages of a twin, with a natural spine for structural loads and system runs, that's also protected by the engines. Brackets and pipes &c to carry the system runs around that vast engine tunnel were ID'd as the source of a lot of the weight problems on JSF.
DZ
Not to start the record again, but would respectfully disagree with the RVL comparison and the F4. Both aircraft have similar weights on recovery, one comes in @130kts ish, one at 40, so obviously energy balance in terms of stopping is very different and much in favour of F35B RVL.
BUT (and it's a biggie) the arrested recovery retains the ability to go around if a number of things go wrong, precisely because the energy (speed and reasonably high thrust) remains. Granted, a lot of things can still go wrong, but there have been millions of arrested landings with a thankfully very low accident rate - very highly trained people (cockpit and deck) making something very difficult look easy.
My continuing concern with RVL is that once committed, you're in a box - it either works or it goes wrong (probably very wrong). All this potential compromise of safety so the B can meet a fundamental performance requirement. I don't care how many times a VAAC Harrier does it on CdeG, it makes me uncomfortable for a number of reasons........
Not to start the record again, but would respectfully disagree with the RVL comparison and the F4. Both aircraft have similar weights on recovery, one comes in @130kts ish, one at 40, so obviously energy balance in terms of stopping is very different and much in favour of F35B RVL.
BUT (and it's a biggie) the arrested recovery retains the ability to go around if a number of things go wrong, precisely because the energy (speed and reasonably high thrust) remains. Granted, a lot of things can still go wrong, but there have been millions of arrested landings with a thankfully very low accident rate - very highly trained people (cockpit and deck) making something very difficult look easy.
My continuing concern with RVL is that once committed, you're in a box - it either works or it goes wrong (probably very wrong). All this potential compromise of safety so the B can meet a fundamental performance requirement. I don't care how many times a VAAC Harrier does it on CdeG, it makes me uncomfortable for a number of reasons........
Last edited by Not_a_boffin; 7th Apr 2010 at 21:05.
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But there's also a lot to be said for the configuration advantages of a twin, with a natural spine for structural loads and system runs, that's also protected by the engines. Brackets and pipes &c to carry the system runs around that vast engine tunnel were ID'd as the source of a lot of the weight problems on JSF.
YF-16 versus YF-17 decisions. The Air Force didn't take your advice.
What a terrible mistake was made,
YF-16 versus YF-17 decisions. The Air Force didn't take your advice.
What a terrible mistake was made,
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What a terrible mistake was made,
However, I bet you're not the sod going for a cold swim some time in the future.........
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There are many finer details to the 1 v 2 engine argument. What it comes down to is if you want the best then you get 2 engines (F22). If you want a cheaper option then you get one engine (F-16 / F35).
SSSSTOWTFC (Single Seat Single Engine The Only Way To Fly Cheaply).
SSSSTOWTFC (Single Seat Single Engine The Only Way To Fly Cheaply).
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1 British pound = 1.5195 U.S. dollars
SSSSTOWTFC (Single Seat Single Engine The Only Way To Fly Cheaply).
)Or to put it another way, (figure taken from F3 crash report ,F3 @£750,000 ) that pays for 131 F3's, so thats 524 Amraam, 524 Asraam ,in the air for defense of the realm. (no idea how many are left in service at present. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
ME - The F-16 was an outright better design, and the YF-17 unexpectedly turned out to be a drag factory.
The one- vs. two-engine debate is not clear-cut at all. However, I'd argue that at any given technology level, smaller aircraft are better off as singles and large ones as twins (because the engines start to get heavy). The definition of small and large tends to change with technology.
The one- vs. two-engine debate is not clear-cut at all. However, I'd argue that at any given technology level, smaller aircraft are better off as singles and large ones as twins (because the engines start to get heavy). The definition of small and large tends to change with technology.