Forum: F-22A Raptor

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

TEG,

The biggest advantage of 3D TV it seems to me is that it enables to do away with the vertical tails. Other than that, 2D would do the trick, all the more that from what I can tell from what I've read, 2D nozzles allow for higher deflection angles.

That's why I suggested canted tails. The way I see it those tails would have to provide just enough controllability to be able to manoeuver the aircraft on their own in case TV cannot be used. For that the current horizontal tails canted at like 30 degrees might be sufficient. (Maybe they could even keep the existing control system but orient it by 30 degrees or whatever. ). Most of the manoeuvring would be provided by the TV. Using the existing horizontal tail would reduce cost as well as drag and weight compared to larger surfaces ( like using the F-18E horizontal tail). But if these tails are not large enough maybe they could be enlarged or lengthened.

The way I see it you want the maximum manoeuvrability in case of a dogfight, which is precisely when you have the maximum thrust from the engines because the AB is used. Since the 232 has 50% more thrust than the F100 installed on the original F-15 SMT, 50% more force would be generated from the TV and possibly a similar level of manoeuvrability would be achieved without the original canards. Even if it's a bit less manoeuvrable it's unlikely to make a significant difference, given the fact that 1) most of the engagements would take place in BVR, especially thanks to the AESA radar and 2) the F-15E will be equipped with HMS.

If one 3D nozzles is inoperative, the engine can be shut down and the nozzle of the other engine can be deactivated. The a/c would continue to fly on its control surfaces.

In case of missile hit, the 2 2D nozzles are likely to be hit too, even if they are probably more survivable. What is the real difference of probability of kill good question.. Also having yaw control from the 3D nozzles would add redundancy with the tails.

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Exactly. Survivability is key. AC like the Super Hornet have a controll law that dictantes that if damage occures to a controll surfance the other surfaces automatically adjust so that the pilot still gets the same flight effect for any given input, assuming it can generate enough force of course.

1) The F-22 can produce high yaw rates because of it's FLCS and large and powerful control surfaces thus elimanating the need for yaw vectoring nozzles.

2) As somewhat mentioned, one of the requirements for the F-22 is to be able to recover from high alpha on control surfaces alone in the event of it's TV nozzles failing.

3) Stealth considerations.

sprstdlyscottsmn wrote:

Exactly. Survivability is key. AC like the Super Hornet have a controll law that dictantes that if damage occures to a controll surfance the other surfaces automatically adjust so that the pilot still gets the same flight effect for any given input, assuming it can generate enough force of course.

Such a capability is sometimes called "Reconfiguration". I'm not sure if it has ever been applied to the F-16 digital FCS, but the IDF in Taiwan had it twenty years ago and the T-50 in Korea about seven years ago.

In those airplanes there is no intent to retain combat capability, just provide enough maneuverability and control to safely return home and land.

Forum: F-22A Raptor

F-22A Thrust Vectoring