RD,
RadicalDisco said:
I was scrolling through yf-23.net when I saw this page.
http://www.yf-23.net/ATFprogramme.html
I was looking at the performance requirements given by the ATF Statement of Operational Need, and I noticed this.
the ability to accelerate from Mach 0.6 to Mach 1 in 20 seconds
the ability to accelerate from Mach 0.8 to Mach 1.8 in 50 seconds at 20-30,000 ft
This second acceleration requirement almost seems silly. I haven't been able to find this figure anywhere else, so is this one of the requirements that got relaxed?
Unload the jet (ala SR-71 dipsydoodle) and, provided you stay inside Q as thermal limits (best to start on the high side of 30K), you can get that, pretty easy.
The ATF engines like to run hot and the intakes have huge ram recovery margins. So there is likely something akin to J79 'T2 Reset' and/or the VMAX switch on the early F100 which opens up the TIT and RPM values on the FADEC under the notional idea of 'best to get through the worst (M.9 - 1.3) quickly'.
Keep in mind that there are performance charts which show the F-22s best entrance to supercruise is 'supersonic from the deck to the tropopause'. Implying that there is a LOT of ram performance in that engine.
That said, there were multiple iterations of the ATF design mooted and it may just be that this spec is the best average as 'aimpoint' threshold from amongst the Co-Op/Agile, SC&M and 'Battlecruiser' configurations, with only the Missileer perhaps left out in the cold, depending on whether you classify it as a Sneaky Pete or Rockwell dual-tandem AAAM type.
In this, I would suggest that people look at the underlying assumptions which eventually drove the ATF demonstrator downselect and compare it to real world mission sets.
Specifically for NATO:
1. Agile.
Really only matters if you have UCAV like agility because it is centered around rapid closure with threats and use of SRMs to get multiple, 'formation kill', shots with weapons that look like the original AIM-132 ASRAAM (triplets of missiles) or the even earlier CLAW (quads). RFLO here helps you stay away from just crippling attrition in the BVR phase but doesn't do a thing to change the likely nature of FA and WARPAC attack doctrines which will be in penny packets (a _lot_ of them) rather than gorilla packages. Simply running down threats will not be easy in a dogfight optimized platform because you don't have the gas and weather may also be an issue because Central Europe is perennially stuck with a 'dual canopy' effect of running scud at 3-5K and a heavier layer around 15. This is in the summer. In winter, the weather can be reduced to rain/snow/sleet. Here, the emphasis -must- be on low drag and high military thrust to zip you between merge fights in a specific acceleration band which supports the use of a very powerful if somewhat conventional turbofan class system since TFs, with a good compression path, will get you through the Mach, they just won't get you far past it. Drop the cockpit, drop the radar, add multi-axis IRST, drop the empennage and essentially have a needlenosed tube with TVC like the F-16 ACTIVE on steroids and you are there. In this, it is likely important that the TAC Brawler simulations all showed that when the ATF concept model pilots wanted to attract the enemy's attention to get a specific reaction, complex turns to expose RCS sensitive aspects were not needed. All that was required was a little blip on the burner to raise the threat level of every IRST fighter in the nose-on vicinty.
2. Cooperative.
Relies on the synergy effect of operating within a friendly IADS whereby -your- RFLO invisibility renders you safe from your own S2A fires and the real question comes from whether you are cuing shots from an infinite magazine of ground launchers (how I would do it) or taking cues from a massively networked (but ultimately static-vulnerable) ground radar system and using your own high-density = folding fin stacked set of internal weapons to shoot shoot shoot. High acceleration here is more about boosting the AMRAAM pol as a midrange weapon or/and the EOSS or URR as NCTR deconflictor (keeping in mind the airspace over the North German Plain is going to be -very- busy, such that 'safe transit corridors' may not work).
3. Battlecruiser.
Is simply about having the longer spear as a repackaged YF-12. It may not be doing Mach-3+ but it will be waaaaay up there in the Mach 2.6 or higher territory and it will be chucking missiles with propellant technology a full two generations later than that which supported GAR-9/AIM-47. This means a genuine Mach 6 or even Mach 8 capability is possible.
The problem of course is that RFLO is nearly pointless, even if it is achievable (cooking the Ferrites) because at high Mach, you are generating an ionization shadow which can be tracked for a hundred nm or more (see UK ATC radars picking up the SR-71 'just fine', halfway out in the Atlantic Approaches). With half the Russian Air Force tailored for the high fast threat (MiG-23/25/31 and Su-15/27), all IRST equipped, this really doesn't make a whole lot of sense unless you have MASSIVE reach on the missile. On the order of 300-400km, minimum. I'll explain why in a minute.
A slightly more useful option is actually the Air to Ground equivalent because the Sovs will have a huge number of radars, far closer to the FLOT and negating these with 90% of USAFE (including the Spang Weasels) dead 20 minutes before the first tank rolls is going to be important. See: PLSS and DME equipped AGM-130 for 'one way to do it' (NLOS SHARK SEAD).
In any case, here your principle requirement is going to be high end with a variable cycle system and heavy emphasis on the upper Mach boundaries for a turbojet which means a lot of gas as 'running start'. You will likely be a weapons release over the Kattegut or the Gulf of Bothnia (depending on approach axis and Swedish promises) and turning off, obliquely, as you come over German territory. Acceleration is largely going to be about how much running room you need and hence where you put the tanker orbits, somewhere over the North Sea.
4. Supersonic Cruise & Maneuver.
The mixed case condition which is actually the least valuable (certainly the most risky) in a European conditioned scenario but the most useful (because it has the best mix of capabilities and particularly all-onboard sensors) in the expeditionary condition.
Bluntly, so long as our interdiction of threat armor remained air and not missile/artillery based (see: Assault Breaker and TGSM/SDVA on TACMS and SADARM on 155.) we were gonna lose a NATO war, just on the associated airbase vulnerability issue. See: Desert Storm and 100hrs of no-roads fighting with six months prep time and nearly even odds armor, compared to WARPAC and 10:1 local, 20:1 total numeric disparities. Hence we actually didn't want to fight there and we kept the peace through Gryphon and Pershing II on an annihilative 'We won't lose, before you do' parity with the Russian SS-20s.
However; 'on the off chance' that something went _really wrong_, we were not going to fight the fair fight because we didn't need to. Using the surfaces and gaps model of tactical thought, what Gen-3 (yes, back then, it _was_ Gen-3, not 4) superfighters of the F-teen generation brought to the battlefield were basic supremacy (ECCM hardening as longer acquisition and guidance range) under local control by E-3 as voice and eventually network vector. If the Soviets copied that within superior airframe as weapon carriage total design, we would be at parity at a time when we could not afford to be jousting with other skyknights on the basis of 'best training and random odds' outcomes with T-72s rolling over Bitburg active under their wings. Hence the old saw as warning: "Day 10 of the war: Two Soviet guards tank division commanders, having tea and pasties in Brussels, one turns to the other and asks: 'Say, who did win the air war anyway?'".
No. If you are going to keep the Soviets fighting dumb, what you have to do is sucker them into playing the way you do and then deflect their predictable approach by taking away their network effect while keeping yours.
And this means killing enablers over the Poland and Byelorus TVDs, not over FRG/GDR. We are talking: A-50, IL-78, Su-24MR, MiG-25BM and their likely MiG-31/Su-27 escorts.
You use your extraordinary force to kill 100 of the top Soviet enabler platforms with ATF and you don't have to get in the attrition rumble with 10,000 MiG-21/23/27/29/Su-17/24/25 over over central Germany, you just have to return the Soviets to all-onboard (which is to say avionics by UVZ Tractor Company) sensorization and no SEAD/EA support. And they will 'lose to ordinary force' F-15/F.3/Mirage 2000/F-16 defenders, quite quickly.
See: Bekaa 1982.
All of which rather puts the point into Sweetman's early _ATF_ quotes on ranges of: '750nm or 1.25hrs flight with half being supersonic.'. Because the only way you can get to the protected sanctuary orbits is if you start in Italy or Greece or Sweden and fly the long axis of a shuttle type mission _as legs not radii_, north to south.
Decent acceleration is still necessary (Stargard SA-10s for one) because maximum range performance from mid-low end supercruise is tied to maximum acceleration performance to cut the circle of the SAM WEZs to a minimum in-crossing. A conventional turbofan will never match to this, because your starting acceleration point is already supersonic. But a 'leaky turbojet' just might. And it is an evolutionary not revolutionary approach because if you look at the later model F100/110 engines they too have undergone massive cycle as bypass change from about .6 down to .36 or so.
I would add here that the F-22 was never supposed to be an F-15 replacement in the sense of it being a massive program for an air superiority (conventional fighting to attritional decision) platform. Why would you want it to be when the key to secrecy is the inverse square of the number of people who know the secret (which is why the F-35 is total joke)?
It was to be an _Air Dominance_ platform which did for the A2A community what the F-117 was supposed to do (but never managed, thanks to a stupid emphasis on SALH laydown in Euroweather: see Serbia 1999) for the strike community in decapitating key assets.
Cheetahs don't hunt wildebeestes. They don't even hunt gazelle. They hunt gazelle fawns. And in this, a supercruise stealth asset is a near unstoppable monster compared to a converted cargo plane. A Mach 5+ AMRAAM has a real range of almost 50nm vs. a Mainstay, less than half this vs. a Flanker.
Smaller mission forces, also mean more investment in technology leverage. Which is why nobody who looked at the spec and knew the industry standards for particularly engine performance, -ever- in fact believed the '35 million F-15 equivalent' costs.
Additionally, what the F-22 gives you in Europe as a worst case condition becomes a Sunday walk in the park in the ME where the operational distances are doubled or even tripled and need to maintain sortie rates mandates a supercruise-by-legs approach to ATO fragging.
The best example of the idiocy of the alternative 'mixed package' approach being the first gorilla raid on downtown Baghdad where even the F-16s which formed the baseline bomb droppers had different engines/inlets and massively different tanker orbit as cruise point requirements. This resulted in major gaps in coverage on the support mission airframes which were even more diverse as 1950s-60s technology F-4G and EF-111.
Made for an interesting day all 'round.
Remove all the mixed performance point profiles as needless penetration aids and what you have is a couple B-52 or 767 based Big Crow SOJAMers; an EC-130 Compass Call; a constellation of Stand Forward, VLE UCAV jammers and perhaps targeters; all playing in the orchestra for little micro packages of F-22s dropping SDB on a 'do this all day' basis of minimum offload from the tankers which are clutched up at ONE orbit point, sufficient to service multiple pass throughs.
600nm at Mach 1.4, hit the tanker; dipsydoodle (unload and burner thru the Mach at high level with minimum induced drag as time spent in the transonics) and throttleup to Mach 1.5+ from fence cross ingress for 300nm to target; dropping a 60-80nm standoff torpedo spread of PGM before turning for home at Mach 1.7+, 300nm to tap the tanker again; 600nm RTB at best Mach for the engine TAC life. Combat turn = rinse/repeat.
Three hours.
Vs. 6-8+ hours for jets like the F-117 which were safe from Al Hussein missiles only so long as they stayed at Khamis Mushayt in the southwest of Saudi.
Acceleration is not as important here except as it indicates overall thrust minus drag functions of aircraft cruise point and power reserves (to avoid fights it doesn't have to win).
POINT BEING: Never trust blanket figures to be more than clues, often false or of 'mixed' nature. Look at the airframe, look at the theater, look at the design pathway (as weapons/sensor mix) and look at what these suggest the platform does best _for the total system appraoch_ to warfare, deriving your own conclusions using brochure numbers as nothing more than potential 'indicators' of what the technology -might- do. If you are willing to pay for it.
