I don’t pay much attention to James Stevenson – his work is full of factual errors aswell as contradictions – his one chart shows the F-22 capable of supercruising at Mach 1.5 at 50kft – his next says it can’t do Mach 1.5 any higher than 45kft – he uses reference wing area as a a metric of measuring performance – yet the F-22s highest lift generating surfaces don’t even fall under its reference wing area – his thrust values are likely to be wrong – and he fails to understand dynamic TWR. He is not privy to any real data – he is an analyst with an agenda – one that over-simplifies things far to much – I wonder if he has any technical qualifications. If pilots are correct and their statements are true the F-22 should be supercruising at Mach 1.5+ at over 50000 ft.

I think the reasoning you spell out is post-facto. LM may have presented it as a justification for their exclusive claim to “Supercruising”, but I don’t think that valid. The marketing hype I’ve seen has always been about 1) the ability to sustain supersonic cruise due to the fuel saving of using dry thrust, not the IR signature while accelerating. The marketing flight profiles suggest penetration of hostile airspace, & engaging hostile aircraft, while flying high & fast, & imply rather strongly that acceleration through the transonic drag hump would be planned to be done well in advance of IR signature being an issue. Also, if your reasoning is correct, why does the F-22 have afterburners at all?

BTW, I wonder what the IR signature of an F-22 at M1.7 at 18000 metres is, even in dry thrust & with all the IR suppression measures it employs?

There is no doubt that fuel savings and increased supersonic persistence are essential to LM marketing strategy. But they have also stressed quite regularly that IR suppression is a big aspect of SC too.

“The marketing flight profiles suggest penetration of hostile airspace, & engaging hostile aircraft, while flying high & fast, & imply rather strongly that acceleration through the transonic drag hump would be planned to be done well in advance of IR signature being an issue.”

Thats the case in an ideal situation – but in reality – the battlespace and events that take place are completely dynamic. Modern sensor systems fitted to FJs have only just started to incorporate the concept of 3 dimensional coverage. Long range sensors only cover small regions of the battlespace – while ESM systems are dependent on aircraft emitting. The only independent full 360 degree sensors we have on our fighters are either RF active MAWs or IR/UV systems – and the state of the art have ranges of no more than 40-50 kms. So to get to my point – combat in a dynamic battlespace, against a compotent adversary will yield situational awareness suprises to even the top end systems like F-22/F-35/Eurofighter/Rafale/Gripen/Superhornet/Su-35. Since the Gulf War – BVR detection and identification ranges and haven’t ever been at the extreme ranges promised by the brochures of the radar developers – even with AWACs present. So for one to assume the F-22 is going to know where its opponents are 100s of miles out in a 360 degree sphere all the time – is wishfull thinking. Thats why having the capability to accelerate quickly to high Mach in dry is an important feature.

Afterburner has a lot of uses – in WVR and BVR – depending on the circumstances.

I would reason it pretty simple.
An F-18 with a2a load cruises at M0.85 at 35000ft with a specific range of 0.130ish (nm/lbs). Going 10% (M0.94ish) faster would cause a drop in SR of 50%.
Going 20% faster (M1.02) causes a drop of ~70% (of that of M.85).
Going 50% faster (M1.3) causes a drop of ~75%.
Going 75% faster (M1.5) causes a drop of ~85%.

I would define supercruise as the ability to fly substantially (more than 50%) faster than the usual M.8-.9 (shortly below the transonic drag rise) with a loss of specific range of less than or maximum of ~50% (we can discuss the number).
Of course, we need to have an aircraft that cruises somehow normal at M.85, so the SR-71 is already out, as is the MiG-25, as both are preposterous gas guzzlers.

That’s it.

As we see, when the F-22 sets the mark, supercruise doesn’t look that exclusively any more.
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At 35kft the F-22 has a 60-70% drop in SR for a ~66% increase in speed. If we assume 50% more speed (M1.35ish) we can (rough visual interpolation) an SR of .35, or somewhere close to a 50-60% drop.

Everybody’s getting what I say?

For advanced readers only:
The specific range is linear connected to specific fuel consumption and glide ratio. Assuming an otherwise unchanged glide ratio, the switch from afterburner thrust (SFC 1.5-2.0 depending on throttle) to dry thrust (at that altitude and Mach number, full thrust, about 1.1-1.3) basically explains most of the savings. Adding few percent aerodynamic efficiency, partly due to optimized stores, we’ll arrive in a rough sketch at 40% increase in SR. Still “cruising” supersonically translates into substantial loss in SR, and if we cruise M1.7 with dry thrust or with reheat does not make the big difference any more, although the 1.7 supercruise speed is the single most hailed performance number of all.
Some people might have a look at my B-58 Christmas Post (http://forum.keypublishing.co.uk/showpost.php?p=1339784&postcount=77), where I show that a B-58 suffers a 60% drop in SR for a doubling of cruise speed. By definition of the F-22 from chart above, the B-58 is already supercruising! And that in 1960!

Hey Schorsch can I get a link on that diagram? If the diagram is real – at the more relavent altitude of 45kft – we are looking at a 66% speed increase from Mach 0.9 to Mach 1.5 – with a drop in SR of 45% – 50%.

Well now, the US engine manufacturers would not want to supply to power a non-US aircraft to compete with a US aircraft? And what if the F136 is not in fact used for the F-35? And what if RR said that they would like the business even if that did not suit LM?

Congress won’t allow US engine manufacturers to sell off the shelf engines to a company that threatens the F-35 program. Selling as many F-35s is key for the US/USAF/USN/USMC/LM and hundreds of other subcontractors scattered throughout the US economy.

Oh no this thread has potential flame war written all over it!

I suppose one needs to go back to who coined the term “supercruise” – but I do believe the original LM definition had merit. It was supposed to work in tandem with their VLO concept of first look, first shot, first kill – be it marketing hype or not. The concept of accelerating to high supersonic – without the use of the AB even for the inital moments of breaking through the transonic region – allowed the jet to be a lot less detectable by IR devices. So I completely understood LMs definition – they were defining the niche that only their jet could practically exploit. We later found out the Typhoon could do this aswell – as could Rafale and Gripen to a lesser degree. Yet as they weren’t dedicated “stealth fighters” and along with the relatively low end supercruise stats being published – the companies producing them didn’t make as much of a fuss as LM. When LM realised this they pushed the supercruise “goal posts” futher along the Mach – claiming you had to be able to do this at Mach 1.5+ to be considered a supercruiser. I was content with the original definition stressing advanced kinematics while remaining relatively stealthy.

not failing to compete directly with the F-35, but aiming at different markets.

say if Switzerland wanted a 5th generation fighter, the F-35 may be a bit over kill. what about a smaller, lighter 5th generation fighter that could be powered by one EJ 2000?

The VLO market isn’t that massive for starters – especially if air policing is the main job for the majority airforces the world over. They just don’t need an aircraft in the F-22/F-35 class and for anything less they have a bunch of jets to go for.

There is no way you can make a multirole tactical fighter with the specs you’ve laid out – it won’t come close to what LM defines as 5th generation. There won’t be a market for a plane that’s far less capable and likely to be as expensive, if not more, due to SAABs lack of experience in the area and the fact you’d need far more airframes to do the same job. If your not looking for “5th gen” – your generally not going to need anything more than what else we have on the market in the non VLO ranks. If you are looking for “5th Gen” your a country with the economics to buy the two options we already have.
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all this mumbo gumbo about Europe can’t making a large fighter engine begs the question..

do some European countries need to make a stealth fighter the size of the F-35?

what if say, Sweden decided to make a stealth fighter with an internal weapons bay about as small as the one on the X45? Could a single EJ2000 give it enough power? Basically a manned version of something like the X45/7.

it will be stealthy, small, maybe cheaper.. and not directly competing with the larger F-35?

No one is saying Europe can’t make a turbofan in the class of the F119/135/136 – RR is doing 40% of GE’s F136. But what I’m saying is Europe doesn’t have such an engine currently, as it opted for the smaller and cheaper EJ200 and M88 – which are fantastic jet engines. SAAB cannot realistically pay for the R&D of an engine in the F135 class – which is exactly what it will have to do unless it goes to Russia. The US won’t be willing to sell its powerplants if it threatens F-35 – especially since SAAB has done so well in the export market already.

I don’t see a point in developing a VLO fighter in the next 10 years that fails to compete with the F-35. Making it VLO entails massive amounts of R&D – verification – validation etc – and who is going to pay for that? Don’t kid yourself – it’s going to be extremely expensive business for SAAB to get to LMs level of experience in designing VLO. So if its less capable from the offset – whats the point?
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