Forum: F-22A Raptor

Elite 1K Joined: May 26, 2005 - 08:39 PM Posts: 1496

The nozzles are "slaved" for vectoring purposes, but I'd assume they can still operate independently of each other to maintain the correct nozzle size for the engine power setting. As to what happens when vectoring is called for when engine power settings are different, well, that's why aero engineers get paid the big bucks! Smile

Nice catch on the J75 hoist TEG, that's awesome!

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TEG is correct (as usual). You can see from the heat distortion that only the #2 engine is running resulting in the closed nozzle on the right and not the left.

The rear of the sling also looks like it is marked for J57 and J52 spreads, as well. PW universal lift-sling for production, most likely.

Kryptid wrote:

I actually have a book that claimed that the YF-22's nozzles could pitch differentially. Was the author wrong or was the feature simply removed for the production F-22A?

Differentially pitching nozzles 'for improving roll rate' actually won't do anything good either for YF-22 or Raptor - actually, it will do things even worse. It was never used on both types.

Following is excerpt from

THRUST VECTOR AIDED MANEUVERING OF THE YF-22 ADVANCED TACTICAL FIGHTER PROTOTYPE
Robert W. Barham
Lockheed Advanced Development Company
1011 Lockheed Way
Palmdale, California 97579 USA

"Pitch control was provided by symmetric movement of
the horizontal tails and engine nozzles when the thrust
vectoring mode was active. The horizontal tails were
sized to insure adequate nose-down pitching moment to
push out of a deep stall at high angles of attack in the
case of a thrust vectoring system failure or dual engine
flameout and were capable of producing pitching moments
sufficient to permit trimmed flight at extreme
angles of attack.

The full span leading edge flaps were used to optimize
the wing camber for better cruise and maneuvering performance
and to improve handling qualities. The leading
edge flaps moved symmetrically in a range from 3
degrees deflection up to 30 degrees deflection down.

Roll control was provided by ailerons, flaperons and,
differential horizontal stabilator - no word of differential nozzle pitching. The vertical tails and
rudder were were sized to provide yaw control for coordinated
rolls at 25 degrees AOA. The rudder provided
directional control and was used to coordinate rolls at
low angles of attack. However, rudder effectiveness as
a roll coordinating device decreased rapidly as angle of
attack increased above 25 degrees. With thrust vectoring
available to provide much of the trim pitching moment
requirement, the aircraft's unique aerodynamics
allowed differential horizontal tail to be used for both
rolling and roll coordination at mid and high angles of attack. Aileron and flaperon effectiveness also decreased
with increasing AOA and contributed little to
the rolling moment at high angles of attack.
Control surface roll authority was limited to prevent
pitch divergence due to kinematic coupling between
angle of attack and sideslip. At all conditions pitch commands
to the horizontal tail were given priority."

For your answer, it must be the welding spots in regards to rest of the structure, hence the shape being uniform in its construction. Thermal dynamics are what are causing this effect.. Some look different than others due to different intensities in their substructures.

TEG thats a nice picture. Its actually the only photograph I've ever seen to show quite a detailed picture of the engines in a production Raptor. Its facinating to note the flameholder design, as it is practically identical to the EJ200. The F119 now use spraybars and continuous rather than staged AB fuel flow, which is a divergance from the -220 and -229. I believe the GE-132 also uses such a flameholder design.

Obi

flateric wrote:

"Roll control was provided by ailerons, flaperons and,
differential horizontal stabilator - no word of differential nozzle pitching. The vertical tails and
rudder were were sized to provide yaw control for coordinated
rolls at 25 degrees AOA. [b]The rudder provided
directional control and was used to coordinate rolls at
low angles of attack. However, rudder effectiveness as
a roll coordinating device decreased rapidly as angle of
attack increased above 25 degrees."

Unlike other aircraft that possess twin vertical tails, the Raptor also seems to be able to send rudder commands to the rudders individually.

Obi

Obi_Offiah wrote:

TEG thats a nice picture. Its actually the only photograph I've ever seen to show quite a detailed picture of the engines in a production Raptor.
Obi

Jay Miller's Raptor book from Aerofax series have a bunch of cool P&W media photos of F119, including nozzle's most intimate internal parts.

flateric wrote:

Jay Miller's Raptor book from Aerofax series have a bunch of cool P&W media photos of F119, including nozzle's most intimate internal parts.

The centerfold, I would assume? Laughing

Forum: F-22A Raptor

Is that your standart Raptor's nozzle?