Forum: General F-22A Raptor forum

While the T-50 flight controls are very unconventional, Im having a hard time accepting the claim of superior agility over the f-22 as a given fact. Ive read somewhere that the Russians are now planning a 2d vector system like the raptor.

Also I'm not getting how the movable lerx would be beneficial, since they only appear to impart a pitch down moment....kinda redundant if you have thrust vectoring.

All moving vertical stabs.... can anyone site the advantages?

From where I sit, the most obvious aerodynamic advantage is the superior wing area.but thats it. Pretty airplane though

what say you all?

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lerx - could improve lift at high AoA. Think of them as an inboard extension of the leading edge flap. Also might improve inlet performance at supersonic speeds, similar to F-14 and F-15 inlets.

All-moving vertical tails - more control power at low speeds and high speeds. The high speed control problem with vertical tail / rudder is loss of effectiveness due to twist of the tail surface, similar to loss of aileron effectiveness due to wing twist. An all-moving tail is much better at maintaining effectiveness at supersonic speeds than is a vertical tail plus rudder.

I'm not sure, if the inlet is fitted with blocker like it needs to be to have a low RCS then I have my doubts about its agility. Dopey Putin saids this yesterday:
"It will be a machine superior to our main competitor, the F-22, in maneuverability, armament and range,"

So you can infer from that that they certainly think it'll be more manueverable. Note what he ommitted in that list though such as avionics, RCS, supercruise and speed.
Persoanlly I think it's a cheap wannabe Raptor knockoff and nothing special, I was expecting a whole lot more considering the hype.

The F-22A has all moving vertical stablaters. For those who doubt, check the following you-tube site: f22 raptor #!v=JTK3zeFRL08&feature=related. Use your pause to check also, the F-22 you want too see appears approximatly 30-40 seconds after video starts, 5-6 seconds after the vido shows f-22's in the dark with lights on.

The next F-22 passes left to right on the screen the one you wish to see is next,passing right to left in what appears to be a knife edge pass.

Sigh, no it does not have all moving verticals and we've been through this before.

shep is right, winger we already had beat that horse to death in a previous thread but for some reason you still think it has all movable verts. It doesn't, it has rudders, get over it and lets move on.

Im totally puzzled with the movable lerx, and not seeing how it would improve lift at Any aoa considering that it only moves down and is far forward of the CG. could it be that it is more of an intake inlet function and we are all assuming it is a flight control?

It would seem that looking at the flanker family, the canard and nozzles as a redundant pitch control combination is something the Russians sold as a great Idea to the Indians but chose to forgo the combo for themselves. I quickly noticed all the other areas Putin and the pilot chose not to claim superiority in as well, but was just curious that so many seem to concede agility to the t-50. f-35 vs t-50.... maybe thats another story.

shep1978 wrote:

I'm not sure, if the inlet is fitted with blocker like it needs to be to have a low RCS then I have my doubts about its agility. Dopey Putin saids this yesterday:
"It will be a machine superior to our main competitor, the F-22, in maneuverability, armament and range,"

So you can infer from that that they certainly think it'll be more manueverable.

Russians love to consider increased ability to yaw as being a major contributor to maneuverability though.

BELA wrote:

Im totally puzzled with the movable lerx, and not seeing how it would improve lift at Any aoa considering that it only moves down and is far forward of the CG.

Re: downward moving lerx. I've thought about how this works before during high AOA turns with the F-22.

http://www.youtube.com/watch?v=PyKYw_p1Hrc

Pause this video at 11 seconds. You can see the leading edge flap of the left wing is down as it performs the high aoa turn.

I think with extremely high aoa turns, once you pass a particular angle, its actually benificial to point your lerxes...etc downward to move the center of pressure forward as much as possible during the turn. In this case, the flap probably also helps with lift on that wing to increase the roll prior to the turn too.

When you approach 90 degrees aoa, the force on your lerx tries to push the nose up and the tail down which is what you want. Effectively it turns the front of the jet into a pivot for the thrust vectoring nozzles to push the back around that pivot.

If you can't generate enough pressure up front, the front of the jet will pitch back initially as you turn hard but as you reach 90 degrees or so, the front decelerates slower than the back does causing your nose to pitch forward....and you get a "cobra" maneuver instead of a turn.

The lerx also might help with airflow to the engines during these turns as I read somewhere that su-27's choke a bit when they pull airshow maneuvers. You can tell from the T-50's intakes that it needs a LOT of air.

What are the disadvantages of an all moving verticle tail setup? If it is so much of an improvement why hasn't it been selected for the F-35 for example?

lampshade111 wrote:

What are the disadvantages of an all moving verticle tail setup? If it is so much of an improvement why hasn't it been selected for the F-35 for example?

A bigger surface mean forces and momentums that act on that area are bigger. Maybe is a trade off in that respect ... Two Cents

lampshade111 wrote:

What are the disadvantages of an all moving verticle tail setup? If it is so much of an improvement why hasn't it been selected for the F-35 for example?

The main drawback comes in form of structural weight. As cfg insisted the all moveable fin puts a higher stress on the airframe and requires a stronger base. It also requires more powerful and by that likely larger & heavier actuators.

Overall I think the PAK FA will exceed the F-22s aerodynamic performance, but may still suffer from its less powerful engine, until the 2nd stage engine is available in 10 years or so. The main concern is whether the Russians will fix the obvious RCS reflectors on a production model and how close they can come in the area of avionics.

The 3-D nozzles plus all moving vertical tails give the PAK-FA better yaw control than the F-22, period.

In terms of actual combat this might be useful for off-axis cannon shots or evading multiple missiles.

However, forward facing control surfaces (such as the moving lerx and those tails) are real bad for RCS. (Not quite as bad as the Eurofighter canards, but still bad.)

Also the round 3-D nozzles on the PAK-FA increase both RCS and IR returns WRT the flat 2-D nozzles on the F-22.

Final result: The PAK-FA will kill the Raptor if it sees it, but those same "features" on the PAK-FA make it much easier for the Raptor to spot and kill it first.

The Raptor's dogfight chances will greatly increase if they ever get around to backporting SAIRST and HOBS from the F-35. (Which the PAK-FA will also have.)

hcobb wrote:

The 3-D nozzles plus all moving vertical tails give the PAK-FA better yaw control than the F-22, period.

In terms of actual combat this might be useful for off-axis cannon shots or evading multiple missiles.

However, forward facing control surfaces (such as the moving lerx and those tails) are real bad for RCS. (Not quite as bad as the Eurofighter canards, but still bad.)

Also the round 3-D nozzles on the PAK-FA increase both RCS and IR returns WRT the flat 2-D nozzles on the F-22.

Final result: The PAK-FA will kill the Raptor if it sees it, but those same "features" on the PAK-FA make it much easier for the Raptor to spot and kill it first.

The Raptor's dogfight chances will greatly increase if they ever get around to backporting SAIRST and HOBS from the F-35. (Which the PAK-FA will also have.)

The PAK FA is going to be using 2D TVC on the production models, so.....there won't be any disadvantages in 2D vs. 3D.

Here's the article from Fox News:

http://www.foxnews.com/scitech/2010/06/ ... er-planes/

Quote:

- Reuters

- June 18, 2010

Putin Boasts Russia's New Fighter Jet Better Than U.S. Planes

Prime Minister Vladimir Putin climbed into the cockpit of Russia's newest fighter jet on Thursday and said it would trump a U.S.-built rival, the F-22 Raptor.

MOSCOW -- Prime Minister Vladimir Putin climbed into the cockpit of Russia's newest fighter jet on Thursday and said it would trump a U.S.-built rival, the F-22 Raptor.

Putin watched a test flight of a "fifth-generation" stealth fighter, dubbed the T-50 and billed as Russia's first all-new warplane since the collapse of the Soviet Union in 1991.

"This machine will be superior to our main competitor, the F-22, in terms of maneuverability, weaponry and range," Putin told the pilot after the flight, according to an account on the government website.

Putin said the plane would cost up to three times less than similar aircraft in the West and could remain in service for 30 to 35 years with upgrades, according to the report.

Successful development of the fighter, built by Sukhoi, is crucial to showing Russia can challenge U.S. technology and modernize its military after a period of post-Soviet decay.

Russia also plans to manufacture T-50s jointly with India.

The F-22 raptor stealth fighter first flew in 1997 and is the only fifth-generation fighter in service. Fifth-generation aircraft have advanced flight and weapons control systems and can cruise at supersonic speeds.

According to the government website, the test pilot told Putin the controls of the T-50 allowed the pilot to operate most of the plane's systems without taking his hands off the joystick, which he said would be very useful under high forces of gravity.

"I know, I've flown," Putin replied. Sukhoi has said the plane should be ready for use in 2015.

The "I know, I've flown" cracks me up . . .

In looking at the Pak fa again, it just occured to me that because of the small size of the verticals, possibly they were forced to go with all moving design to preempt/negate a possible deficiency. rather than impart an advantage?
Control power in yaw axis is usually a fraction of what is needed in pitch axis, Could it be possible that the all moving verts are simply the end result of restoring control power lost in an attempt to minimize Rcs with overall smaller verts?

Re: movable lerx

With the example of the raptor and other planes that use maneuvering leading edge flaps, the control force is very close to the cg, which is not the case with the leading edge movable vert on the t-50.

To my mind, the question seems to be if they are attempting to be a virtual canard? or are they designed to be a virtual flap set? lack of up movement prevents full canard function. Nose down pitch affect would seem to eliminate them from being used as flaps. correct?

Forum: General F-22A Raptor forum

superior agilty over the f-22