PAK FA - T50 at M

Originally posted by ZIVONIC
reply to post by MisterBurns

 

Regarding missiles, it's a size game. Fuel and efficiency. Russia is currently the world leader in long range missile technology, although many seem to be able to produce good MRAAMs, that should not even have to be pointed out. Russian SAMs and anti-ship missiles have no rivals.

Keep in mind, these long range AtA missiles are more like cruise missiles than AA-12s and AIM 120s. Much consideration went into the T-50s weapon bays to accommodate these larger payloads.

But Cruise Missiles are more like UAVs than missiles, they arent supersonic are they? So the fuel and efficiency, wouldnt that be an air breathing scramjet rather than a solid rocket which all the Russians seem to be, and yet, even the AirBreathing Missiles (Meteor) arent even close to 250km?

reply to post by waynos


State test usually test the applicability, and capability of the aircraft in the VVS, along with making sure components reach the specs set by the government, and is often done after the serial model is complete. If the PAK FA tests anything like the SU-34, the serial engine test should be done quickly, it will not take 5 years. NPO Saturn is doing all the developmental testing at this time.

My question is, is this the serial engine or "item 127", which is the second stage engine on the research chain?

AL-41F1 >>> item 127 >>> unnamed serial model

reply to post by MisterBurns


I'm not an expert in this field, but both KS-172 and R-37, achieve their ranges differently. KS-172 was a very long projectile with very little drag. The size and fuel load gave it its range, that's fairly obvious. R-37 has large fins that run along the body, they are there to create lift, the burn time is controlled to optimize the glide range of the missiles.

Regarding ramjets vs solid fuel, I cannot say much. Ramjets have their engines with them for the duration of their flight, solid burns their fuel probably loosing weight much faster. There are so many variables, you really cannot say which is the better, longer range method of propulsion.

Thanks for the reply. I do have a question about the T-50 if anyone can answer it. Can anyone tell me what a couple of the features are that are visible from underneath?

The ones in question are the, apparently stealthily profiled, bumps visible between the wing and the intake and the array-like feature on the underside of the tail?

Both features are clearly visible in the image linked below

www.airliners.net...&sid=252c59113943bf7939d9426bc4743151

reply to post by waynos



Those are quick release stations for side winders.

The news i heard when i last read about the F-22 is that Russian Radar could spot the F-22 coming over the horizon and easily guide its assets to intercept.

If the US AWACS was to be any effect for the F-22 it had to fly lead over the horizon. That is probably why the Russians are manufacturing long range AA assets to take it out at a early phase. The Russians have three jet fighter who can do this besides the T-50. (MIG 31. MIG 35. SU 30/35).

reply to post by waynos

Waynos,

The aft array appears to be the rear weapons bay and I am assuming the shortened "bee sting" carriers either ECM and/or an aft quadrant conformal radar array or at least it will someday. Same goes for the two projections between the DSI intakes and the forward wing root. My belief is that they are for side looking arrays and or ELINT/ECM gear. I doubt that they are for SRAAM's as they simply aren't big enough and anyway why wouldn't you bury bays for such within the structure to reduce RCS? The only reason you would compromise such RCS would be for something actually worthy or better than stealth (or short range missiles for that matter) and that implies either a monitoring function or an active EA system that requires at least some directional attribute. It certainly is not a fairing for some form of actuator as I read somewhere. It is interesting to note as an aside that the main actuators for the wing trailing surfaces are housed in canoe fairings. This to me implies that the wing is either to thin for them or packed with fuel to the point they simply wont fit. This is curious as I would have thought that their impact upon RCS and aerodynamic performance would have seen them buried within the wing structure even if it was at the expense of range. Then again this is a prototype so maybe the production example will see this change?

LEE.

Thanks for the informative replies guys

The question that is still vexing me though are the rib-like array under the tailplane surface. Is this some form of passive detector array, or are they simply strengthening ribs?

reply to post by waynos


Waynos,

Here is one persons interpretation of what those are:
Quick Bays



However, some believe that it might be the housing for the LERX controls.

We will find out, when it is built I guess.

Thanks for replying on the "bumps" but I think people aren't understanding what is the second feature that I'm asking about. Look at the image I linked to and if you study the tailplanes there is a series of lines on the surface of each one. That is the unusual feature I am asking about. I can only imagine that it is either a strengthening of the structure, or, more adventurously, some kind of detection system or similar. If it's the former it suggests poor engineering,, which is not something I would expect of Sukhoi.

reply to post by waynos


I'm not sure if they are for reinforcing or if they are relevent?

I imagine the tail will get a new look once they finish prelim flight testing and start RCS testing...just a guess.

However, back to the reinforcing. If you look at this picture (top of horizontal stablizer)

you will notice that the stabilizer ribs are parellel to the wing tip. The markings on the bottom are not (it is very sutble, but they are not parallel). It would be kind of odd to have ribs offset like that, as it could cause a bit of a structural nightmere.

It is worth noting though, that the bumbs do align fairly well with wind travel over the wing. Maybe they are to decrease wind wash speed giving the stabalizer more effective 'power'. But, that wouldn't make much sense being on only one side.

Could just be a sloppy job of covering actuaters, especially if they know the stabalizer design is changing in the future.

Link

There are some pictures here which seems to show a similar number of spars and rivets to those markings on the underside.

The pictures I mention are the cutaway PAK_FA Provisional and the one above with the tails dropped down.

Not sure if having sensors on a controll surface (especially such a big one) is a good design as they might not present the same data if they are in a different position. I could be way off the ball park here but most of the sensors work of sensing something in relation to your aircraft.

So if you imagine a top down view of your aircraft. Coming out the front in a cone is the radar receiver, attached to the fuselage are RW receivers and you might have some in your leading edges (but not the krueger flaps) which would show detection cones coming out of the side of your aircraft.

If you put a sensor on the moving tail depending on its position, whater if was receivng could easily move position from being below you to in front of you as you push the stick forwards, of course a computer could work it out and correct it but thats more programming.

I would go for early prototype marks as these are not production aircraft, the tooling and finishing may all change.

MisterBurns, I completely agree with the point you made about placing a detector device on a moving surface, which is why I was puzzled by them. A revealing thing for me concerning the page you linked to is that the feature does not appear at all anywhere on that page. Indeed on the very last photograph, near the bottom, showing the first prototype from below it is clear that they are totally absent from under the tail, so this is a feature of the second prototype only, so far.

Unfortunately this doesn't prove anything either way as both conclusions still make sense

Either it was found that the taileron on airframe no2 needed strengthening ( which I agree with peck can be designed out later on) or it carries "more equipment" than no1.

At the moment I think the first explanation is most likely, but I thought I might have found something new

reply to post by waynos


No I absolutely agree, that tail is different from the others, i searched heaps of photos on line and there was one with (your picture) and many without.

Be interesting to see the outcome!

I have no publicly linkable source for this, but I have been reliably told that the features Waynos refers to are nothing more than airflow and structural bending sensors for the airframe validation test suite.

Ok Waynos,

I have taken another look at the picture. Sorry I did misinterpret what you were referring to regarding the horizontal stabilizer. There is little doubt to me that they are doublers for structural reinforcement. In particular the odd shaped large one on the inboard of the stabs looks like a classic crack repair doubler especially as it is inboard where I would expect to see the most amount of stress around the hinge point/actuator mount. This kind of thing is not unusual in new aircraft designs and prototypes. In fact it's not unusual to see on a lot of modern airliners after a few years of service wear and tear and the inevitable dings, scrapes, scratches and cracks this brings. There is one particular doubler you will see on 737 cockpit windows that has a funny shape. And a quick perusal of a lot of cargo hold door cut outs will often reveal some unusual shapes.

In the case of the T-50 I would say testing has revealed some structural reinforcement is necessary although given the effect that such patches will have on RCS you can bet any production example will have reinforcement internally. Or perhaps a completely redesigned horizontal stab a la the YF-22/F-22.

LEE.

Originally posted by thebozeian
Or perhaps a completely redesigned horizontal stab a la the YF-22/F-22.

LEE.

Its worth noting that there was very little carried over from the YF-22 that won the fly-offs to the F-22 - the internal structure is different, the jet pipes are different, the tail structure is different, the wings are different, the jet intakes are different, the cockpit changed place significantly, and the nose is different.

Lockheed basically started with a blank slate when they were awarded the F-22 contract, and the same goes for the F-35 contract - the "contract winning" aircraft bear little in relation to the aircraft now being produced.

Lee & Richard, thanks lads, yes, I can see how it would be that

Originally posted by MisterBurns
Regarding missiles, it's a size game. Fuel and efficiency. Russia is currently the world leader in long range missile technology, although many seem to be able to produce good MRAAMs, that should not even have to be pointed out. Russian SAMs and anti-ship missiles have no rivals.

Keep in mind, these long range AtA missiles are more like cruise missiles than AA-12s and AIM 120s. Much consideration went into the T-50s weapon bays to accommodate these larger payloads.

But Cruise Missiles are more like UAVs than missiles, they arent supersonic are they? So the fuel and efficiency, wouldnt that be an air breathing scramjet rather than a solid rocket which all the Russians seem to be, and yet, even the AirBreathing Missiles (Meteor) arent even close to 250km?

The russians have supersonic long range anti shipping missiles since the early 80's at least.see:
en.wikipedia.org...

Also long range AA missiles have been around for quite some time, see the Phoenix and the missiles the MIG31 and the MIG 25 have.

reply to post by tomcat ha


They have ramjet propulsion, not scramjet propulsion.

Anyways, choosing ramjet over solid fuel doesn't mean the missile will have more range, there are many factors which determine capability.

Yeah, I didn't notice anything that would tell me it uses thrust vectoring, but it looks similar to many other Stealth planes out and coming out.

Well, I've just done a little research. The T50 indeed does have thrust vectoring.