Sukhoi Su-57 / T-50 / PAK FA - flight testing and development Part II [2012-current]

[TaiidanTomcat]

Also, General Zelin also said PAK-FA max speed will exceed F-22. http://en.rian.ru/military_news/20120213/171286237.html

“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.”


Read more: http://defensetech.org/2010/06/18/putin-declares-new-russian-built-pak-fa-stealth-fighter-better-than-f-22-raptor/#ixzz2aARpke1V
Defense.org

All of this must be true because it was said.

So why should we trust Metz's word but not Zelin?

Because it was on APA of course, the same people you were telling us were credible earlier, plus the F-22 is a operational, fully tested aircraft. The Pak Fa is still in testing.

 

[flateric]

it's not direct citation from Zelin, but reporter's own add-on.
if you note, Zelin never said 'supercruise speed' inside of asterisks

 

[EricChase88]

it's not direct citation from Zelin, but reporter's own add-on.
if you note, Zelin never said 'supercruise speed' inside of asterisks

“After a comparative analysis of the fighter’s characteristics with the U.S. F-22 Raptor and Chinese J-20 stealth aircraft, we can conclude that PAK FA exceeds the foreign analogues in maximum speed, flight range, maximum takeoff weight and the maximum overload value,” Zelin added.

Zelin said T-50 will have greater max speed. Mikhailov said supercruise speed is now Mach 2.

 

[flateric]

Mikhailov said supercruise speed is now Mach 2.

Where? Direct citation from him, please.

 

[flateric]

Zelin also said that Russia’s T-50 outstripped its U.S. and Chinese analogues.
“After a comparative analysis of the fighter’s characteristics with the U.S. F-22 Raptor and Chinese J-20 stealth aircraft, we can conclude that PAK FA exceeds the foreign analogues in [...] maximum takeoff weight"

that's really funny point

 

[EricChase88]

Mikhailov said supercruise speed is now Mach 2.

Where? Direct citation from him, please.

"Одновременно с исчезновением призрачной надежды на индийские деньги понижались требования к новому самолету. Так, главком ВВС Владимир Михайлов снизил на 0,15 М крейсерскую скорость: «К примеру, задана характеристика 2,15 М, чтобы самолет летал с такой скоростью, однако это число – 0,15 – влечет за собой необходимость усиления киля и увеличение веса самолета». По его словам, анализ эксплуатации самолетов типа Су-27 и МиГ-31 показывает, что хотя они и способны ходить примерно на таких скоростях, но редко на них выходят..."

"Along with the disappearance of the illusory hopes on Indian money went down the requirements for new aircraft. Thus, the Air Force Commander Vladimir Mikhailov reduced by 0.15 m Cruising speed: "For example, given a description of 2.15 M, the aircraft flew so fast, but this number - 0.15 - entails the need to strengthen the keel and weight gain the aircraft. "According to him, the analysis of aircraft such as the Su-27 and MiG-31 shows that although they are able to walk around at those speeds, but they rarely go out ... "

Cruise speed changed to Mach 2 from 2.15.

 

[flateric]

I've read this already. Once more, 'cruising speed' was added by media and never was spoken by Mikhailov himself.
Fast self-introduction into world of modern composites and kinetic heating will bring you surprising results.

 

[EricChase88]

Then why do people say F-22 can exceed Mach 2? Why do people trust him when he say 1600 mph?

 

[flateric]

which people? saying exactly what? that F-22 can _supercruise_ over M=2.0 or that it's _max speed_ is over M=2.0?
and that Mach - at what altitude?

 

[bring_it_on]

Then why do people say F-22 can exceed Mach 2? Why do people trust him when he say 1600 mph?

The F-22 does not supercruise @ Mach 2. The developer publishes FTD on its website, you can see the best figure they give i mach 1.72, against a program requirement of mach 1.5. The Top speed is classified, some say it is limited to mach2 or just below, the pilot has said that it can go @ mach 2, since the top speed is classified and only dubbed as Mach 2 class with supercruise capability , the claim that it can do mach 2, is hardly contradicting the official USAF position.


F-22 Flight test Data :

http://www.f22-raptor.com/technology/data.html

Official USAF Fact-sheet mentioning its Top Speed As " Mach 2 Class"

http://www.af.mil/information/factsheets/factsheet.asp?id=199

 

[EricChase88]

which people? saying exactly what? that F-22 can _supercruise_ over M=2.0 or that it's _max speed_ is over M=2.0?
and that Mach - at what altitude?

Metz said 1600 mph. Why should we believe him? Why don't we believe Zelin when he said T-50 is faster?

 

[flateric]

you now have jumped from cruise speed to maximum speed I see
I don't see any reasons to not believe both Metz and Zelin regarding _max speed_ numbers (in second case I think we should after all wait for Stage 2 engines to be sure)
a question just is at what altitude and most important - how long

 

[flanker]

As far as i know, he himself never said "cruising speed".

крейсерскую скорость means cruising speed. This is directly from interview.

I am perfectly able to read russian, thank you. I will repeat: He did NOT say "cruising speed" himself.

 

[EricChase88]

you now have jumped from cruise speed to maximum speed I see
I don't see any reasons to not believe both Metz and Zelin regarding _max speed_ numbers (in second case I think we should after all wait for Stage 2 engines to be sure)
a question just is at what altitude and most important - how long

If Metz said 1600 mph max speed for F-22 and Zelin said T-50 max speed is higher, then Mach 2 max speed for PAK-FA is too low and can't be true.

 

[flanker]

Zelin says many things.

 

[EricChase88]

Zelin says many things.

If Mikhailov really is talking about max speed, why believe him instead of Zelin?

 

[flateric]

Question is if Zelin ever knew real maximum speed of F-22 (or do believe in 1600 mph) - which I hardly doubt. They still insist that F-22 RCS is around 0.3 sq.m.
http://www.aviaport.ru/digest/2006/01/18/99775.html
Citing report (by respected ARMS-TASS) from Mikhailov's 2006 press-conf, he has ordered to drop speed requested in RFP from M=2.15 to M=2.0

 

[flateric]

Zelin says many things.

They both do, well, we both know it well.
Mikhailov is famous with half dozen of quite bad PAK FA maiden flight prognoses, but I think he was just repeating what he was promised.
In 2006 he was promising first flight in 2007.
http://newsru.com/arch/russia/15jun2006/samolet.html

 

[flateric]

EricChase88, one can cheat public, or even try to cheat DIA, CIA and US DoD, but none can cheat physics, chemistry and thermodynamics.
It would be good citation for Ben Rich, I say.

 

[EricChase88]

So why should we trust Paul Metz claim of 1600 mph max speed?

Chief designer of T-50 Davydenko said TTZ requirements of PAK-FA is superior to F-22. He also said F-22 RCS is 0.3-0.4 sq.m, which is similar to PAK-FA requirements. Also, Mach 2 speed requirement was changed in 2004, and that is 6 years before T-50 first flight, so thats a lot of time for them to change the speed requirement.

http://paralay.net/pakfa/pakfa.html

 

[sferrin]

So why should we trust Paul Metz claim of 1600 mph max speed?

Uh, maybe because he was the Chief Test pilot and probably has first hand experience? And for the record, that wasn't the max speed. The exact quote was, "the top speed is classified but it'll do sixteen hundred miles per hour".

 

[EricChase88]

So why should we trust Paul Metz claim of 1600 mph max speed?

Uh, maybe because he was the Chief Test pilot and probably has first hand experience? And for the record, that wasn't the max speed. The exact quote was, "the top speed is classified but it'll do sixteen hundred miles per hour".

Metz's 1600 mph claim for F-22 is around for a long time, so Zelin most likely know that figure. He also know things about T-50 performance we don't, so if he say T-50 is higher max speed, we can trust him.

 

[flanker]

*sigh*

 

[Dreamfighter]

*sigh*

Indeed, it is getting really silly.


It looks like some are doing their very best to turn this usually informative site into another forum for the most simplistic fanboys. I hope these people are as supermaneouvrable as an F-22 or a PAK-FA and make a sustained turn(back) to wherever they came from.

back to lurking again

 

[Radical]

Well, a quick and dirty approximation of how much faster the PAK-FA might supercruise when it gets the second stage engines. Assuming that Product 30 produces 107 kN of dry thrust and 117 engine produces 88 kN, that's a 21.6% thrust increase. The square root of 1.216 is 1.103. I think drag coefficient will decrease with greater supersonic speeds, so if Product 30 goes as planned, the T-50 should supercruise at least 10% faster (maybe up to 15%) than with current engines according to this admittedly simplistic approximation. Its still impressive nonetheless. Suppose it's meeting a hypothetical Mach 1.6 supercruise requirement right now, then it might make Mach 1.8 with Product 30.

Wasn't it reported that T-50 exceeded supercruise requirement even with 117 engines?

 

[bring_it_on]

When is the new engine expected to be ready?

 

[saintkatanalegacy]

Next decade...

 

[Radical]

Next decade...

Really? According to this article, it's 2015.

http://www.ruaviation.com/news/2012/11/15/1341/

 

[saintkatanalegacy]

test and ready are different things B)

 

[Radical]

So why should we trust Paul Metz claim of 1600 mph max speed?

Chief designer of T-50 Davydenko said TTZ requirements of PAK-FA is superior to F-22. He also said F-22 RCS is 0.3-0.4 sq.m, which is similar to PAK-FA requirements. Also, Mach 2 speed requirement was changed in 2004, and that is 6 years before T-50 first flight, so thats a lot of time for them to change the speed requirement.

http://paralay.net/pakfa/pakfa.html

I am rather curious about how they arrived at the 0.3 to 0.4 sqm figure. Davydenko obviously isn't stupid, but this claim is perplexing. Of course the official 0.0001 sqm is for optimal angles, but 0.3 to 0.4 is hard to believe.

Also, the part regarding "TTZ" (which I'm guessing is the same as KPP) is written as this.

- initially in TTZ the superiority over F-22 is put that logically considering a large supply on time when developing T-50

It appears to be badly translated Russian text. Any idea what that line is supposed to mean or what it was originally?

 

[Trident]

I've read this already. Once more, 'cruising speed' was added by media and never was spoken by Mikhailov himself.

Equally he did not specifically say 'maximum speed' though, did he?

Fast self-introduction into world of modern composites and kinetic heating will bring you surprising results.

Well, if his quote referred to maximum speed, the composite materials argument does not wash however - as the F-22 hitting (possibly more than) 1600mph with similar (arguably less modern) materials demonstrates. So on what basis do we automatically assume that an (otherwise unspecified) speed requirement which is further cut from a figure that is already significantly slower than ~ Mach 2.4+ represents maximum speed? Especially when certain other aspects of the T-50 design indicate that considerable effort was made to obtain low drag and good inlet pressure recovery at speeds in excess of Mach 2.0 - why do so, with the attendant compromises in weight and cost, when the aircraft is not expected to operate at such speeds at all?
I think it's perfectly reasonable to at least entertain the possibility that it was indeed the supercruise requirement that got dropped to Mach 2.0 rather than dismissing the notion out of hand.

Zelin says many things.

They both do, well, we both know it well.

Well, if we're in the business of casting doubt on Mikhailov's technical competence, why trust him even if he did say 'maximum speed'? He might not be clued in on the finer points of supercruise as opposed to top speed. See where I'm going? There might not be enough substance to this quote to conclude that the supercruise requirement is ultimately Mach 2.0, but at the same time it is also impossible to categorically exclude this possibility, bearing in mind certain characteristic features of the T-50 design.

 

[flanker]

Equally he did not specifically say 'maximum speed' though, did he?

I see you are playing devils advocate. ;D (not a bad thing)

He did not state if it was for cruising or maximum speed, but one can kinda do some word trickery/juggle and deduce what he meant. He stated the reason for lowering requirement was need of strengthening the tails, and hence weight increase.

I assume that higher speed = higher stress on the frame. Even tho that max speed stress occurs over much smaller period of time than cruising speed. In other words, 2 min at max speed is worse for the frame than being at cruising speed for lets say 10 min. Hence, the higher speed, the more robust it has to be.

Lets say he was talking about cruising speed. So if the frame is not robust enough to handle mach 2.15 (cruising speed) surely it wouldnt be robust enough to handle top speed, lets say mach 2.5. Hence i personally assume he spoke of top speed.

Again, I base that on assumption that forces at higher speed is more violent than at lower, although at lower speed the lower forces occur for much longer time. I would be interested in if my speed/stress assumption is correct or not.

 

[sferrin]

Shall we stir the pot some more?

This quote is from several years back:

"And then there is the Raptor's super cruise capability that lets it fly at supersonic speed without using fuel-guzzling afterburners as required by other fighters.

"That saves us a lot of gas and opens up a whole host of things when you start talking about dropping bombs," Krumm said. "You can imagine if you are 60,000 feet doing mach 1.9 (about 1,400 mph) and these bombs are flying out of your airplane, the swath of hell you can produce going through a country saying 'I'll take that target, and that target'."

 

[Trident]

I see you are playing devils advocate. ;D (not a bad thing)

I assume that higher speed = higher stress on the frame. Even tho that max speed stress occurs over much smaller period of time than cruising speed. In other words, 2 min at max speed is worse for the frame than being at cruising speed for lets say 10 min. Hence, the higher speed, the more robust it has to be.

As you've alluded to yourself here, a major component in determining the stress is time - in fact it has a huge impact. Hence the ability of the F-22 to apparently hit ~ Mach 2.4 in a dash, with materials very similar to the T-50.

I assume that higher speed = higher stress on the frame. Even tho that max speed stress occurs over much smaller period of time than cruising speed. In other words, 2 min at max speed is worse for the frame than being at cruising speed for lets say 10 min. Hence, the higher speed, the more robust it has to be.

Again, it's not a simple as that - if the requirement was to sustain Mach 2.15 for (say) 20 minutes but Mach 2.5 for only 2 it would probably be the other way round. 'Thermal soak' is the keyword here - i.e. the critical structure does not heat up to its thermal equilibrium temperature for a given flight condition instantaneously and if you slow back down quickly enough you can briefly hit speeds which the airframe would not be able to cope with in thermal steady state.
You cannot reliably make such a deduction without knowing the time for which those speeds are supposed to be maintained according to the requirements laid down.
And if it comes to that, why build features into the aircraft at great cost which are basically pointless unless it is to be capable of comfortably exceeding Mach 2.0 at least transiently when you don't want it to be that fast in the first place?

"That saves us a lot of gas and opens up a whole host of things when you start talking about dropping bombs," Krumm said. "You can imagine if you are 60,000 feet doing mach 1.9 (about 1,400 mph) and these bombs are flying out of your airplane, the swath of hell you can produce going through a country saying 'I'll take that target, and that target'."

Which, assuming for argument's sake that it is true, serves as further evidence that Mach 2.0 supercruise isn't all that outlandish.

 

[Sundog]

Regarding Trident's point about the thermal limits of the materials, one must also consider that parts of the Raptor airframe are actively cooled for IR signature reasons. So considering the material limits becomes problematic without know the cooling rates as well.

Also, it isn't unreasonable to think the T-50 uses the same technology as well. So thinking of it in terms of basic limits, without knowing what is designed into either airframe enters into completely baseless arguments both ways. We can make guesses at the end of the day, which is really what we're doing. Which is fine, as long as we remember that, though they may be educated guesses, they're still just guesses. At least until either side starts givings us their plots of the actual flight tested flight envelopes. I haven't seen those posts from them yet.

At the end of the day, I've come to the conclusion that the Raptor is almost an excellent operational fighter; It's still lacking some systems and I still find the "Raptor Cough" untenable. The T-50 as it currently exists, is an excellent design as well and the airframes seem to be doing well in flight tests. However, it's still a long way off from being a fighter, and even further still from being operational in any sort of number that means anything. But I haven't any doubt that when Russia does get them built and operational they'll be excellent fighters.

 

[flanker]

'Thermal soak' is the keyword here - i.e. the critical structure does not heat up to its thermal equilibrium temperature for a given flight condition instantaneously and if you slow back down quickly enough you can briefly hit speeds which the airframe would not be able to cope with in thermal steady state.

I wasn't talking about thermal issue, and neither did Mikhailov directly atleast.

 

[sferrin]

Which, assuming for argument's sake that it is true, serves as further evidence that Mach 2.0 supercruise isn't all that outlandish.

Sure, with the right engines and materials. I don't see the T-50 sporting a pair of F119s anytime soon, nor does Russia have the huge industrial base to tap from when it comes to composites expertise.

 

[Radical]

I rather doubt that either the F-22 or T-50 will be supercruising at Mach 2. We have to look at the context of what Mikhailov said. I found another version of the interview (source: flanker), and I'll bold the part I think is important.

В.Михайлов сообщил, что снизил на 0,15 число "М", заданные в тактико-техническом задании характеристики скорости нового самолета".
"К примеру, задана характеристика 2,15М, чтобы самолет летал с такой скоростью, однако это число - 0,15 влечет за собой необходимость усиления киля, увеличение веса самолета", - сказал главком.
По его словам, "анализ эксплуатации самолетов типа Су-27 и МиГ-31 показывает, что эти самолеты, хоть и способны ходить примерно на этих скоростях, но редко на них выходят".
"Зафиксировано всего лишь несколько полетов летчиков-испытателей на таких скоростях, это влечет сотни проблемных вопросов по усилению хвостового оперения и плохо сказывается на других характеристиках самолета", - сказал В.Михайлов.

Mikhailov said that the number was reduced with 0.15 "M", set in the tactical and technical characteristics of the job rate of the new aircraft. "
"For example, given a description of 2.15 m, so that the aircraft was flying at such a rate, but the number - 0.15 leads to the need to strengthen the keel, increased weight of the aircraft," - said the commander in chief.
According to him, "the analysis of aircraft such as the Su-27 and MiG-31 shows that the aircraft, though able to walk around at these speeds, but they rarely go out."
"Lock only a few test pilots flying at such speeds, it involves hundreds of problematic issues to strengthen the tail and has a bad effect on the other characteristics of the aircraft," - said Mikhailov.

Judging from this, I would have to say that he is talking in the context of max speed, not supercruise. F-22 won't be cruising Mach 2 either. Max official supercruise figure I've seen is Mach 1.78 in a Aviation Week press release, and as I recall, this was when LM really wanted to secure more orders for the aircraft before it got capped.

 

[sferrin]

Judging from this, I would have to say that he is talking in the context of max speed, not supercruise. F-22 won't be doing Mach 2 either. Max official figure I've seen is Mach 1.78 in a Aviation Week press release.

"And then there is the Raptor's super cruise capability that lets it fly at supersonic speed without using fuel-guzzling afterburners as required by other fighters.

"That saves us a lot of gas and opens up a whole host of things when you start talking about dropping bombs," Krumm said. "You can imagine if you are 60,000 feet doing mach 1.9 (about 1,400 mph) and these bombs are flying out of your airplane, the swath of hell you can produce going through a country saying 'I'll take that target, and that target'."

I guess this actual F-22 pilot lied. :

 

[flateric]

From Sukhoi paper ca.2006

Front-line fighters have their own critical performance requirements for the use of composites in the design. In this case, the share of composites applications is most affected by the maximum airspeed - more precisely, a Mach number.

The largest share of composites application with a maximum weight effect can be realized in the design of the front-line fighter aircraft with a maximum flight speed of 2.1 M, as the range of temperatures of airframe skin surface lay within the range of operating temperatures of the existing composites.

However, in this case, there are areas with increased operating temperature, where the use of composites is practically impossible, like nacelles of powerplant based on augmented turbofans, especially in the afterburners area. Due to the large thrust-weight ratio of modern front-line fighter and dimension of modern powerplants the mass fraction of metallic nacelles in the airframe is quite large.

The absence of metal armor and less stringent requirements for repair in the field can significantly extend the use of composites in the construction of the front-line fighter in comparison to attack aircrafts, so composites can be widely used in the fuselage, wing and empennage.

Domestic front-line fighters are intended for operations from non-prepated runways, and that limits the application of composites
in the lower and side surfaces of the mid-fuselage and aft-fuselage, as well as lower part of horizontal tail. But forward fuselage, in contrast to attack aircrafts, can be built mainly from composites.

Erosion problems with the leading edges of the wings and tail of the front-line fighters are as valid as the for the ground attack aircrafts. The difference in the sweep angle of the leading edges of the wing and tail is compensated by an increase of the maximum flight speed at sea level.

For front-line fighter with a maximum speed of flight M=2.1-2.35, there are additional restrictions on the use of existing composites in the area of air intakes and air duct of power plants due to deceleration of airflow to subsonic speeds with heating.

For supersonic interceptor with a maximum flight speed of M=2.35 use of existing composites in load-bearing structures is almost impossible, because their level of heat resistance does not cover the interceptor's operating temperature range. Here composites
can be used successfully only in airframe parts, protected from aerodynamic heating, such as equipment bays, and crew cabin.

Development of the new composites with high level of mechanical and thermal stability and higher performance than the metal alloys is a complex scientific and technical challenge, since the strength of composites more determined by the strength of the polymer matrix and the strength of its connection to the reinforcing filler, the mechanical properties of all polymers with increasing temperature faster fall than mechanical properties of the
metal alloys. Possible progress in heat resistance composite materials is associated with the use of metallic, ceramic and carbon matrix, but their mechanical properties close to those of metal alloys, price is excessively high, and manufacturability is lowered.