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Elite Joined: May 26, 2005 Posts: 1093

From published pictures and assuming a wingspan of 44' 6", the engine nozzles are about 4' 3" apart center-to-center.

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To quote Tinito_16"If the engine nozzles of the F-22 are'nt mechanically linked to each other, there is no reason.. to prevent the nozzles from operating asymmetrically." I don't think we'll see the F-22's FULL capabilities (like differental thrust) at an airshow for QUITE some time (if ever). Have to wait 'til it gets bloodied (so to speak) in combat for that one I believe. Two Cents

Guysmiley wrote:

From published pictures and assuming a wingspan of 44' 6", the engine nozzles are about 4' 3" apart center-to-center.

Assuming max. nozzle deflection (20°) and 35,000 lbs. thrust per side, the total amount of torque produced by "opposing" nozzles would be around 51,000 lb-ft. (rearward thrust would go down to around 66,000 lbs.).

The question now is, how does that torque number compare to the torque produced by the stabs and ailerons? For instance, with the ailerons set much further apart than the nozzles, the torque might actually be quite a bit higher. In a similar vein, the stabs have a lot of surface area, and they too are positionned further off the centerline.

I'm guessing the "smart guys" went through all this number crunching during the design phase and decided that differential TV just wasn't worth the effort, or that any gain in roll rate would be trivial at best.

That said, differential TV would probably make more sense in a jet with its engines set further apart, which would yield far greater torque for any given deflection and/or thrust value.

Indeed em745, you are right. The F-22 could roll faster with differential tv, but an aircraft such as the YF-23 for example, with it's engines far apart, would get the most out of something like that. It's hard to maneuver an aircraft at slow speeds however, so in a slow dogfight even the F-22 could use it. However the F-22 probably (and hopefully) wont get into slow knifefights like that.

I wonder if the F-35 has a good roll rate... it looks kind of portly but everyone "in the know" says it's the F-16's equal or better in every aspect. I suspect that while a clean F-16 has a hell of a roll rate, when you put weapons on the wings it makes it exponentially harder to roll. So, a fighter like the F-35 (or F-22 for that matter) which has the weapons stored internally, close to the center of mass, will have a higher combat roll rate than even the F-16 when heavily loaded with weapons.

I'm wondering... With all the moving parts in the F-22 that can affect performance, is a situation where one or both of the nozzles stuck recoverable? I'm almost sure if a surface gets stuck (depending of course on the severity and other damage that might be present) the plane can at least be landed. Suppose the t.v. nozzles are stuck in the full up position: what should the pilot do?

Elite Joined: May 26, 2005 Posts: 1093

Quote:

I'm almost sure if a surface gets stuck...the plane can at least be landed.

Depends on which surface and how it failed as well as the intestinal fortitude of the pilot. Ask Gums about how much fun landing with a failed LEF is sometime.

Heck with the B-2 crash we've seen that a little moisture in the wrong spot at the wrong time can lead to losing an aircraft.

But to your question, I'm assuming the engineers have considered such a scenario and the mechanical mechanism and/or the control laws are designed to handle such a failure. But in high performance military aircraft if all else fails, there's always ejection...

Veteran Joined: Feb 25, 2007 Posts: 434 Status: Offline

Prayer is also a viable option. Laughing

Elite Joined: Jul 22, 2005 Posts: 965 Status: Offline

Guysmiley wrote:

Heck with the B-2 crash we've seen that a little moisture in the wrong spot at the wrong time can lead to losing an aircraft.

I don't know what kind of failure is more disconcerting, the kind mentioned above or something like a manufacturing flaw causing structural failure. Sad

nice addition to the routine
http://www.youtube.com/watch?v=P3fWiz8vTWg

Elite Joined: Jul 20, 2005 Posts: 1031 Status: Offline

The only major additions were a loaded roll and a high AoA/slow speed pass. Everything else was simply re-worked from the initial routine developed. They flew a Raptor/Red Arrows formation today (Saturday) at the airshow. Not sure you'll get it tomorrow though.

Guysmiley wrote:

But to your question, I'm assuming the engineers have considered such a scenario and the mechanical mechanism and/or the control laws are designed to handle such a failure.

That was my thought as well. I mean, if the FLCS is "smart" enough to handle a virtual speed brake, then it wouldn't be too much of a stretch (IMO) to throw in a few extra lines of code to handle a stuck nozzle.

Anything to reduce the odds that a mechanical failure would be the cause of a pilot having to ditch a $135M+ plane.

strykerxo wrote:

nice addition to the routine
http://www.youtube.com/watch?v=P3fWiz8vTWg

johann posted these on ASB:
http://www.youtube.com/watch?v=mJeH44Rd08g
http://www.youtube.com/watch?v=wtiOaHq-ZjU

I know it is a little tweak to the routine. This is just another example of the F-22's prowess, seeing an AC throw together a string of m/v in one pass is stunning. Although the loaded roll is fairly simple it is visually pleasing, realizing that an AC of that size can M/V it's way out of a paper bag. I have been waiting many years to see this plane do it's thang, and every new twist is just icing on the cake.

It is so impressive to see the F-22 flying along side of the Red Arrows, as it did with the Thunderbirds. You can realy see the scale between the two AC.

Mental break, or flight of fancy.
What would an F-22 demo team such a the Thunderbirds, be like?

strykerxo wrote:

What would an F-22 demo team such a the Thunderbirds, be like?

Um... prohibitively expensive would be my guess. Razz

Looks great, I wonder what the flight display would be like with 6 F-22 or opposing, T/V their way way through the sky

Veteran Joined: May 26, 2008 Posts: 288 Status: Offline

strykerxo wrote:

Looks great, I wonder what the flight display would be like with 6 F-22 or opposing, T/V their way way through the sky

Well, other than the fact that the airplane pictured is actually a YF-22, don't hold your breath for a Raptor Thunderbird team. If the USAF only winds up getting 180 or so, there won't be spare airframes to go around. More likely it will be the F-35, and that won't happen for at least another 10 years or so.

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