Forum: F-22A Raptor

Hello, I was wondering, why after all of the intensive research done by NASA (e.g. F-16 MATV, F-18 HARV, X-29, F-15 Active...) and plane manufacturers, was it necessary to leave out the side to side thrust vectoring motion? It just seems like the multi axis thrust vectoring is the way to go. It seems to really work well for the darn SU-37. Is the lack of this capability able to be made up elsewhere? Every time I view any of the MATV/HARV flight demonstrations, they seem so "Super Maneuverable".

I understand that maneuverability isn't everything, because, classic merges seem to have become rare and the F-22/F-35 dominate the field with just avionics alone but it's just strange that they wouldn't add that touch of additional assurance...that cherry on top.

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If I had to guess, the reason the F-22 has only 2-D TVC instead of 3-D TVC is because it's simpler and can potentially provide better IR signature suppression. Each of the Raptor's nozzles look to be composed of two plates that are opposed to one-another and can therefore constrict the hot exhaust flow into a narrow slit by closing together. If you wanted yaw-control in the TVC, you'd have to add extra parts to the nozzle design. This would also change the shape of the nozzle and potentially give it a higher radar-cross section.

Also, for an aircraft like the F-22, thrust-vectoring in the pitch axis is more useful than thrust-vectoring in the yaw axis. This is because pitch is used when making tight turns after the aircraft banks. Yaw TVC can have some usefulness, but not as much so in standard maneuvers.

I do believe that the X-44 MANTA, which was to be based on the F-22, would have had 3-D TVC. This was supposed to make up for a lack of vertical tails and rudders.

On any other non-stealthy platform you may have a point. This is mere speculation on my part but, for the Raptor, with it's exhaust tucked between the stabs, 3D TV wasn't an option due to yaw axis gimbal limits and the final design of the stabs. The Raptor is not only stealthy in the RF spectrum, but to decrease it's IR signature, the nozzles were put where they are so the flight control surfaces nearby can offer some shielding. Maybe not quite the same amount that, say, the F-117s V-tail did, but some shielding nonetheless.

That, plus with the advent of greatly improved flight control computers and software, the flight controls themselves can move the jet around in the yaw axis in much the same fashion as a conventional 3D nozzle would.

seeing as how in demos the raptor goes up, stalls, and while falling at near 80-90 AOA is able to yaw one direction, stop, yaw the other direction, then power out of the descent and climb away... does it really need 3-d TVC? BTW, MATV and HARV were both so agile not just because of their TVC, but because they had TVC mounted to 25-30,000 lb aircraft. Raptor weighs in higher than that with no gas.

Late in the ATF development program the AF had dropped the requirement for thrust reversing, sighting cost, weight and complexity. Northrop dropped TV/reversing claiming the aerodynamic and FCS was sufficient to meet the required characteristics. Lockheed however choose to keep the TV less the thrust reverser.

The F-15 SMTD demonstrated both TV & reversing
http://en.wikipedia.org/wiki/F-15_S/MTD Crazy Pilot

The US has chose not to pursue TV on the F-35, while the Russians taughted the SU-37's TV capabilities. The US has worked on TV for many years and have pursued a different course. That tells you alot about what the US thinks is important and what the future of air combat will look like, or why many worldwide AC manufacturers have not followed the Russian lead.

Why have TVC on planes if you can't outmaneuver missiles?

There is obviously some utility to TV, pitch & yaw rates are enhanced. The F-35 and F-18D/E will be able to pitch and yaw without TV, under full control. The F-22 and SuperBug can yaw without departing because of their FCS, albeit slightly slower than the Su-37. The SuperBug can pitch up and nose over at high rates w/o TV. Check out some of the videos on Youtube.

Missiles can be spoofed electronically, decoyed, jammed and jinking. Missiles are not unbeatable.

I read some time ago that where TV is realized is at high altitude where the air is thinner and FC surfaces are less effective.

The tactic here is to not be seen and avoid the merge with an AC or missile. Take the high road and control the airspace to your advantage, although there is always the unforeseen.

strykerxo wrote:

Late in the ATF development program the AF had dropped the requirement for thrust reversing, sighting cost, weight and complexity. Northrop dropped TV/reversing claiming the aerodynamic and FCS was sufficient to meet the required characteristics. Lockheed however choose to keep the TV less the thrust reverser.

The US has chose not to pursue TV on the F-35, while the Russians taughted the SU-37's TV capabilities. The US has worked on TV for many years and have pursued a different course. That tells you alot about what the US thinks is important and what the future of air combat will look like, or why many worldwide AC manufacturers have not followed the Russian lead.

I'll second what STRYKERXO has said...

Cost, weight, and complexity. (Complexity = expensive to maintain and lower reliability)

His point about US and other "worldwide AC Manufacturers" not using TV is very valid. After ALL that R&D money, there hasn't been much interest in the technology. Don't forget both the F100 and F110 had TV nozzles developed during the late 80's early 90's and neither have ever seen installation outside testing.

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TEG

Very well, thank you very much for the replies...taken as a whole, it seems that all of these comments have added up to the same points, of which, it is understandable. Cost, IR Signature/Compromising stealth, other ways to achieve the same effect...thanks very much!

You have to admit though, that thrust-reversing element included on F-22s TV would have added a helluva a bonus - at what relative cost to the entire program? TR could be designed to be employed for tactical maneuver breaking and for the obvious short/damaged runway landing capability. A further added capability would be the ol' Swedish invention of roadway landing tactics and planning. In 10 years out, it should be assumed that with every potential 'post-cold war' adversary and their hired unconventional, hostile gun, could be armed with precision guided airbase altering missile ordnance (or other asymmetrical implementation). That must be the 'going-forward' strategic assumption: i.e., one's airbase could be less than operable at any time during high-tempo ops.

For that point, profile me in the camp at the least supporting repowering F-15E with GE-132 2-D TV w/Thrust Reversing...

Why not just chance all F-15E to ACTIVE standard then? F/A-18 horizontal stabilizers added to the intakes as canards (the things are massive) with GE-132 (or PW 30K+ class motor) 3-D TVC. When I talked to the guys who work with her (the ACTIVE) they said there is nothing they cant out accelerate or out turn, even a Raptor, but the ACTIVE is not a line fighter, more of a tech bed demonstrator.

That_Engine_Guy wrote:

His point about US and other "worldwide AC Manufacturers" not using TV is very valid. After ALL that R&D money, there hasn't been much interest in the technology. Don't forget both the F100 and F110 had TV nozzles developed during the late 80's early 90's and neither have ever seen installation outside testing

I agree that with all the money and programs, that there is a lot of interest in TV. But, except for the Russians who flaunt their only selling point in the face of the F-22/35 a fifth generation 1-2 punch, the west has not seen the need to pursue this technology beyond testing, on to frontline AC.

Not that it is not a useful tool, and may get to the point of reducing weight and drag by the elimination of tail surfaces, faster pitch and yaw rates as well as provide more control. The tailless UCAVS and the F-35 a fifth generation fighter AC do not have TV.

The AF has had to come to some conclusions and consensus when it comes to this technology. Maybe that flippant comment by AF pilots about the Su-37 demo, “that it is great for air shows” is more telling than at first listen.

I read somewhere that 3d TV was'nt needed because the oversized rudders basically pushed the -22 in the yaw axis quick enough.

Forum Veteran Joined: Apr 16, 2005 - 03:16 PM Posts: 800

Concerning the F-15, why not remove the horizontal and vertical tails completly and install the canard control system instead of the horizontal tail control system? They could even keep the horizontal tail, no need for an F-18 tail. If it's not large enough, maybe an F-18E horizontal tail.

Both the tails and the TV would provide yaw and pitch control.

Moreover from looking at the pictures it seems that the gun has to be removed to install the canards.

Now that the F-15 is equipped with HMS, I imagine that more manoeuvrability than that would be overkill. All the more that the more powerfull the engines are the more force the TV can generate. With ~35000lbs in full AB per engine during a dogfight the force generated would be huge.

Viperalltheway wrote:

Concerning the F-15, why not remove the horizontal and vertical tails completly and install the canard control system instead of the horizontal tail control system? They could even keep the horizontal tail, no need for an F-18 tail. If it's not large enough, maybe an F-18E horizontal tail.

Both the tails and the TV would provide yaw and pitch control.

But you guys have to remember a simple heater shot against such an Eagle could most likely damage both nozzles even if it didn't "hit."

Nozzles can jam easily when damaged, and in a combat situation (IE not testing/airshows) a stuck TV nozzle could spell doom for an aircraft without conventional control surfaces.

The Raptor's system is much simpler than a 3-D nozzle, and with the huge conventional stabs it allows backup in the event of a TV failure.

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TEG

Forum: F-22A Raptor

F-22A Thrust Vectoring