Forum: General F-22A Raptor forum

If you count the TVC as a pair of control surfaces on each engine, then you would have to count the "turkey feathers" on the F-16 as a control surface.

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As much groaning has been recorded over the F-22's costs, imagine the heart ache when they would have chosen the YF-23 and had to cap the builds to half the quantity.

The increase in supercruise speed can be attributed to P&W increasing the fan diameter of their engine and making it bigger to actually meet the thrust requirements laid down in the initial competition for an aircraft in the weight class of a production model ATF. That, and there may have been changes in the aircraft's inlets to allow for better pressure recoveries and other sorts of upgrades.

Does the F-22 have fixed or variable inlets? (My sources differ on this.)

The J-20 and F-35 go DSI and so are sharply limited in their effective speeds.

hcobb wrote:

If you count the TVC as a pair of control surfaces on each engine, then you would have to count the "turkey feathers" on the F-16 as a control surface.

I didn't know the F-16's "turkey feathers" were capable of effecting pitching moments.

Rolling Eyes

hcobb wrote:

Does the F-22 have fixed or variable inlets? (My sources differ on this.)

Fixed.

He is showing more and more to be a troll......clearly does not understand or thing through before he posts. Look at his posts on some of the other threads.

The TVC vanes act together to adjust the flow from the engine, in much the same way as the "turkey feathers" do. If you subtract that out then they function together as a single control surface. The two vanes on each engine can't act wildly differently without having a big impact on the functioning of that engine.

No, they do not act the same way. Study the operation of the balance-beam nozzle on the F100 and then compare to the TVC nozzle on the F119. Not the same at all. The only similarity is that both nozzles have variable exit area, beyond that there is no similarity. The F100 nozzle gives no directional control, the TVC does.

hcobb wrote:

The TVC vanes act together to adjust the flow from the engine, in much the same way as the "turkey feathers" do. If you subtract that out then they function together as a single control surface. The two vanes on each engine can't act wildly differently without having a big impact on the functioning of that engine.

First off 'turkey feathers' are the 'external nozzle segments' on the modern military convergent-divergent nozzle equipped engines. F-15 and B-1 do not have 'turkey feathers' (AKA external segments) installed, BUT do have a convergent-divergent nozzle. Con-Di nozzles do affect thrust but only in an axial direction. more/less along the center-line of the engine. Many use the 'turkey feather' moniker referring to all the moving parts within the nozzle, but this only indicates unfamiliarity with a modern nozzle or how it operates. There are 105 moving parts in a PW Viper's nozzle, to some they ALL "turkey feathers", but to an engine guy/gal, there are only 15 on the OUTSIDE of the nozzle that are nothing more than aerodynamics.

In a PW F100 balanced beam, convergent-divergent nozzle there are the following;

Balance Segments
Balance Seals
Convergent Segments
Convergent Seals
Divergent Segments
Divergent Seals
External Segments - AKA "Turkey Feathers" (Not on USAF F-15)

There are 15 of each of these (105 total) the comprise the Viper's round nozzle inside/out, connected together by levers and links to a large driven synchronizing ring, that moves everything together at once via 5 mechanical actuators, air driven by a controller that is directed by the engine's DEEC (FADEC) for proper scheduling of the nozzle.

In the F100 pitch yaw nozzle additional actuators could independently vary the angle of the nozzle with flight control inputs while the area of the nozzle was consistent for proper engine operation. This nozzle was heavier and much more complicated than the base F100 nozzle. It was never put into production, but was tested. (GE had a similar nozzle for the F110)

As for functioning together? Do you know how a Con-Di nozzle operates? Or how one steers thrust with a vectoring nozzle?

On the F119, it has upper/lower segments along the same line as the F100. The engine can vary the nozzle ratio for operation, while the nozzle moves independently for flight control input. This steers a portion of the thrust up/down off axis.

The last sentence "The two vanes on each engine can't act wildly differently without having a big impact on the functioning of that engine"

Where are you trolling here? Engine nozzles aren't "trailing engine edge flaps'

The nozzles have EVERYTHING to do with the engine's operation. Nozzles control, or help control a multitude of parameters within the engine. Pressure Ratio, Turbine Temperature, Stall Margin, RPM, etc can all be affected/controlled by the nozzle's ratio/throat (Aj)

In vectoring nozzles (particularly the F100's PYBBN) not only could the Aj (Throat) of the nozzle be controlled, but the Ae (Exit) could also be varied independently to deal with flow separation during specific vector parameters.

The nozzles (vectoring or not) have little to do with the flight control function of an aircraft. Besides the external nozzle segments "Turkey Feathers" aiding in drag reduction they impart little deflection force to the aircraft's flight path. The aerodynamics/drag of of nozzle is more important with higher thrust engines or where engines are spaced close. Why the 'turkey feathers' were removed from American F-15 and B-1 where the feathers were wearing prematurely or jamming causing nozzle malfunction; quick-fix - amputate the feathers!

The F119's nozzles operate in a similar Con-Di Nozzle manner, but can independently be 'steered' with the aircraft's flight control system to provide a thrust-input to aid in pitch; done by deflecting a percentage of the thrust component up/down from the engine's center-line.

Some of NASA/PW's F100 pitch/yaw tests show that about 4000lbs of thrust per engine could be vectored 20*. This is a far cry from the 29,000lbs of total thrust each engine is capable of producing. While this may not seem like much in numbers, at low airspeed, or high altitude, (where flight controls loose bite) a 4 ton shove 20* in any direction is quite a push. This didn't seem to be enough advantage, or applicable enough for actual combat operations for the increased weight/cost/complexity of the nozzles. To date no F100/F110 production has seen the vectoring nozzles. The F-35 program also did not require T/V nozzle. Their benefits just don't justify the cost.

So what was the point here? Or are we trolling for engine nozzle information?

TEG

EDIT - PS Read this and get back with me...
http://www.nasa.gov/centers/dryden/pdf/ ... H-2267.pdf

TEG, as usual with your posts, extremely detailed and right on the money. I don't know how you have the energy or patience to put it all in words. Not Worthy

Agreed, TEG always gives great reads

Forum: General F-22A Raptor forum

YF-22 vs YF-23