F-35's future competition: PAK-FA

superraptor wrote:Maybe not only airshow audiences. Keep in mind that Russian and Indian Engineers have 5 to 6 years to work out the bugs. I would not be surprised if its stealth characteristics are comparable to the F-35. It then would not matter if the f-35 could carry 6 Aim120 Ds internally because they could not lock on. In return the F-35 with its superhot F135 engine would remain a target for IR-seeking missiles (that's why mabe the cooler F136 would be a better choice). I think the missiles Israel is developping for the F-35 have radar and IR seeking modes which we also should consider for all US Amraam missiles. The PAK FA will be a game changer because of its range. Let''s assume the Russians and Indians will acquire 250 each, Venezuela 50, Iran 100, Syria 100, North Vietnam 50. How do you keep a US aircraft carrier group in the Persian gulf from being targeted if your opponent has a long range stealth strike fighter? The answer could be to move from projecting forward fire power through aircraft carrier groups and forward based tactical aircraft to long range strike platforms such as the the B-1R which could be based in the US or Diego Carcia. Equipped with JASSM-ERs it could take out almost any target. It also would be invisible to radar as it can fly below it. Why waste tens of billions of dollars on the development of a new deep strike stealth bomber when it would not take muchh to put the B-1R into production while reducing the number of aircraft carrier groups and air bases in the Gulf, South Korea and Japan at the same time.

A- it's a big assumption that the T-50's RCS will be as good as the F-35s
B- you do realize that IR signature reduction is part of the F-35's design right?
C- Iran will never get T-50s, and it's doubtful that Syria, Vietnam would either. In any event, I fail to see how Venezuelan, Syrian, and Vietnamese T-50s would pose a threat to a CBG near the Persian Gulf.
D- the AMRAAM wouldn't have to look for the T-50 until it was close enough to see it. It has 2 way data links, and would be receiving targeting data from sensors that could see the T-50.

wrightwing wrote:

superraptor wrote:Maybe not only airshow audiences. Keep in mind that Russian and Indian Engineers have 5 to 6 years to work out the bugs. I would not be surprised if its stealth characteristics are comparable to the F-35. It then would not matter if the f-35 could carry 6 Aim120 Ds internally because they could not lock on. In return the F-35 with its superhot F135 engine would remain a target for IR-seeking missiles (that's why mabe the cooler F136 would be a better choice). I think the missiles Israel is developping for the F-35 have radar and IR seeking modes which we also should consider for all US Amraam missiles. The PAK FA will be a game changer because of its range. Let''s assume the Russians and Indians will acquire 250 each, Venezuela 50, Iran 100, Syria 100, North Vietnam 50. How do you keep a US aircraft carrier group in the Persian gulf from being targeted if your opponent has a long range stealth strike fighter? The answer could be to move from projecting forward fire power through aircraft carrier groups and forward based tactical aircraft to long range strike platforms such as the the B-1R which could be based in the US or Diego Carcia. Equipped with JASSM-ERs it could take out almost any target. It also would be invisible to radar as it can fly below it. Why waste tens of billions of dollars on the development of a new deep strike stealth bomber when it would not take muchh to put the B-1R into production while reducing the number of aircraft carrier groups and air bases in the Gulf, South Korea and Japan at the same time.

A- it's a big assumption that the T-50's RCS will be as good as the F-35s
B- you do realize that IR signature reduction is part of the F-35's design right?
C- Iran will never get T-50s, and it's doubtful that Syria, Vietnam would either. In any event, I fail to see how Venezuelan, Syrian, and Vietnamese T-50s would pose a threat to a CBG near the Persian Gulf.
D- the AMRAAM wouldn't have to look for the T-50 until it was close enough to see it. It has 2 way data links, and would be receiving targeting data from sensors that could see the T-50.

- we don't know how stealthy the T-50 is, but to hope that it is not is not a good strategy.
-enlighten me how the ultrahot engine core of the f-35 can be obscured through an IR-reduction package.
- Syria is quite close to the Persian Gulf

What I understand as defenses against IR missiles:
- flares against older IR seekers
- visual stealth coatings around aircraft wings, tails and structure to confuse missile seekers cued by target shape
- Full FOV DIRCM based on lasers to zap IR seekers will be standard in the future.
- other classified stuff we don't know about

superraptor wrote:- we don't know how stealthy the T-50 is, but to hope that it is not is not a good strategy.

It's not a question of hope, it's plain to see (to anyone with even a hint of engineering knowledge) that the design will not lend itself to the same level of radar stealth as the F-35.

superraptor wrote:-enlighten me how the ultrahot engine core of the f-35 can be obscured through an IR-reduction package.

The F-135 and F-136 are both higher bypass engines than, say, the F119. We can safely assume that, if the T-50 is intended to have the same supercruise capability as the F-22 then its engines will be closer in bypass ratio to the F119 (i.e. lower BPR) and hence hotter than the F-135. Then multiply that by two (or maybe sqrt(2)......how does one add two lots of IR energy?!) and you've got a package nett IR signature higher than that of the F-35.

Or, to put it another way, the IR signature of the F-35 is lower than its current 5th gen peers. Scratch that.....that should be peer, singular.....we'll call the T-50 a peer when it's flying in a form more representative of its production guise.

superraptor wrote:- we don't know how stealthy the T-50 is, but to hope that it is not is not a good strategy.

It is not going to be on a par with the F-35 that is for sure, not unless they completely redesign the intakes anyway...

shep1978 wrote:It is not going to be on a par with the F-35 that is for sure, not unless they completely redesign the intakes anyway...

The intakes arent' much of a problem IMO - you can always put a blocker into it. There are other bigger problems with the T-50 (RCS related).

exec wrote:

shep1978 wrote:It is not going to be on a par with the F-35 that is for sure, not unless they completely redesign the intakes anyway...

The intakes arent' much of a problem IMO - you can always put a blocker into it. There are other bigger problems with the T-50 (RCS related).

True, they could always put a blocker in there but from what I understand blockers are far from an ideal (S-duct) solution because they somewhat strangle the airfow and because they add additional complexity and maintenance problems/issues due to them having to cope with potential ice buildup.

( I could well be wrong on the ice thing, not 100% sure )


What are the other possible problems you can see with its RCS? Care to tell as i'm certainly interested and i'm sure others would like to hear...
(The underside springs to mind as a possible bad area to me)

exec wrote:

shep1978 wrote:It is not going to be on a par with the F-35 that is for sure, not unless they completely redesign the intakes anyway...

The intakes arent' much of a problem IMO - you can always put a blocker into it. There are other bigger problems with the T-50 (RCS related).

Sure, put blockers in the inlets and watch how the engine's loose performance, especially at high speed. What do you think MACH+ inlet shock-waves will do inside that inlet with one or more 'blockers'? I'm guessing choke. Not to mention the additional ram-drag of the additional hardware in the air-stream.

Ever notice the B-1A had a MACH 2+ top-end with the original inlets but only about MACH 1.2 with the B-1B's 'blocker' inlets?

Also notice how the F-117 didn't use blockers or go supersonic? I doubt you get good supersonic airflow through a screen door...

NONE of the US stealth designs have used 'blockers' since the B-1's retro-fit from supersonic-bomber, to LO low-level penetrator.

The only way to get proper airflow performance from the inlet and get LO; it must be sufficiently 'trunked' to mask the inlets, without doing so in a manner to limit flow. It also needs to have the proper shape/size to handle the maximum airflow of the engine at all speeds without capturing too much air or the added ram-drag will help kill the engine's performance too.

IE - "Radar Blockers" in the inlets are performance killers.

Keep 'em flyin'
TEG

Making Supersonic Inlet Design Easier Posted by Graham Warwick at 6/1/2010

http://www.aviationweek.com/aw/blogs/de ... d=blogDest

"Inlet design has been a black art since the invention of the jet engine, and designing an inlet that works well at subsonic and supersonic speeds has always been a challenge (ask the F-111 folks). Now Boeing has received a US patent for a multi-path inlet concept that promises to make aircraft-engine integration and optimization an easier task.

Boeing's multi-path inlet comprises a two-dimensional array of elements, or passages, each shaped to compress and deliver air to the engine. This tackles one of the challenges - designing an intake with sufficient length to provide the required compression that fits in the limited space available. The array inlet, according to the patent, can provide the same compression with one-tenth the length, making it easier to integrate the inlet in a wider variety of locations on the aircraft.

The array inlet can be attached to a movable mounting to tackle one of the other design challenges. Supersonic aircraft need to "start" the inlet by first swallowing external shock waves to establish stable flow conditions inside the duct. If the inlet is "unstarted" and the shock waves remain outside, engine thrust is reduced. Starting typically requires a variable-geometry inlet that adds weight and complexity, the patent says.

In Boeing's design, the movable array inlet would start in a position that provides a larger frontal area and airflow. When the aircraft accelerates to supersonic speed, the 2D array would move to a position that reduces frontal area until the shocks are swallowed, typically in less than a second, then move to a third position with greater frontal area but which could vary with speed and altitude. A flexible duct would link the movable array to the engine.

There are other aspects to the Boeing concept, including making the array conical or conformal to the aircraft's contours and using the outer elements of the array to remove boundary-layer air. And the individual passages don't need to be four-sided, the patent states: they could have three sides for compactness, or six for strength.

Me, I'm off to doodle a few ideas...

All graphics: USPTO

[Superficially it looks like the F-117's inlet, but that was an inlet screen for stealth and did not direct or compress the airflow.]"

According to comments at above webpage - here is another place to go:

http://www.google.com/patents/about?id=QDzGAAAAEBAJ

[EDIT} Somehow previous edit - to highlight this point - became lost in thread entry above. The comments in original story about this make other points with perhaps a potential for 'stealth' in this idea. Don't know myself though.

That_Engine_Guy wrote:NONE of the US stealth designs have used 'blockers' since the B-1's retro-fit from supersonic-bomber, to LO low-level penetrator.

F-18E radar blocker:

http://epiqs.smugmug.com/Airplanes/Mili ... RjJ6-M.jpg

YF-23 radar blocker:

http://data3.primeportal.net/hangar/how ... _of_51.jpg

X-32 radar blocker:

http://attach.high-g.net/attachments/x_32_167.jpg

They are all supersonic aircrafts capable of doing more than a Mach 1.5.

I'm not sure, but maybe even the F-22 and 35 have some kind of a radar blocker behind their s-shaped inlets.

Fourth prototype of the T-50 will probably have a radar blocker installed.

exec wrote:F-18E radar blocker:

http://epiqs.smugmug.com/Airplanes/Mili ... RjJ6-M.jpg

YF-23 radar blocker:

http://data3.primeportal.net/hangar/how ... _of_51.jpg

X-32 radar blocker:

http://attach.high-g.net/attachments/x_32_167.jpg

They are all supersonic aircrafts capable of doing more than a Mach 1.5.

I'm not sure, but maybe even the F-22 and 35 have some kind of a radar blocker behind their s-shaped inlets.

Fourth prototype of the T-50 will probably have a radar blocker installed.

Hate to break it to you Exec, but all that you're seeing in those photos are the inlet guide vanes of the engines themselves. Now they may or may not be treated in some manner, but they will not 'hide' the fan rotors behind. You are viewing the variable vane portion (they're hinged like a flap) in the closed position like they would be with the engine at low or idle RPM. The variable inlet vanes, or compressor inlet variable vanes, help regulate air-flow into the fan (compressor) to help control stall margin. In effect they act as a 'choke-plate' to keep the engine from ingesting too much air.

I'll add the X-32 used the JSF119-614 for which photos are difficult to find so I've given examples of the F119 (which was also in the YF-23 displayed at the USAF Museum) and the F135 (which looks as if it's CIVVs are being covered over with something red?)

I've also included the F100-PW-229's photo, the CIVVs are clearly visible.

Most the modern military augmented turbofans have VIVs or CIVVs ahead of the fan (N1) rotor. They AREN'T like commercial engines where the first stage fan blades meet the air first. (IE-no need for super-sonic stall margin) An example is also pictured.

Keep 'em flyin'
TEG

F135


F119


F414


CFM-56

That_Engine_Guy wrote:
Hate to break it to you Exec, but all that you're seeing in those photos are the inlet guide vanes of the engines themselves.

I know you're the engine expert here, but I think you're wrong on this one.

Again - F-18E radar blocker:
http://s48.radikal.ru/i122/0912/38/7ba23d14c6c8.jpg
http://img441.imageshack.us/i/radarblocker.jpg/

Do you still think it's not a blocker?

I think that we can see something similar here:
http://data3.primeportal.net/hangar/how ... _of_51.jpg

The engine seems to be behind this 'thing'.

Look at the F119 picture - guide vanes defienietly look different than what we can see on the YF-23 intake picture (F119 guide vanes are 'vertical').

I think you're right about X-32 - on this picture it's probably tghe engine visible. But since it's a stealth aircraft and it has a very straight intake...
http://attach.high-g.net/attachments/x_32_174.jpg

The question is - how did they manage to keep it VLO without using a blocker or something similar?

I highly respect the engine guy on every post he contributes, but I have to concur w/ exec that the odds are favoring some kind of actual PAK-FA inlet blocker (per their claim), just as the soon to fly F-15SE is supposedly to be equipped with a blocker in their respective completed version (per BA's claim).

Now if only an F-16XL could be advertised with a future inlet-blocking PW232 or GE132 powerplant. Air forces around the world would put things on hold and ask for more info...

When the PAK-FA is fielded what AAM's will it carry and will they be superior to US or Western Types used by the F-35????