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

icyplanetnhc (Steve) said:
I’m frankly being charitable here. Marchukov stated that the Su-57 with the AL-41F1 does not achieve supersonic cruise without afterburners. Given that the Su-35 with the AL-41F1S attained Mach 1.1 without afterburners, I presumed that the Su-57 is capable of achieving the same, and that supersonic cruise refers to speeds beyond transonic region (Mach 0.8-1.2), hence Mach 1.3 or so.

An aircraft having components that are designed to operate beyond the overall system’s boundaries is not new, nor is it unique to Sukhoi. The North American Rockwell B-1B retains the same engine as the B-1A, despite being designed for Mach 1.25 rather than the latter’s Mach 2.2 top speed. The F-22’s APGS likewise has a design altitude limit well in excess of the aircraft’s operational limit. I’m not saying this is definitely the case with the Su-57, but it’s a possibility.
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On the one hand you have Bogdan stating the big difference in acceleration of the Su-57 vs Su-35 and the need to take care to avoid going supersonic without noticing, then you don't exactly know what interpretation of "supercruising" Marchukov is referring to, since that term used to mean flying faster than 1.5M on mil power, when it was coined. Several legacy planes were known to be able to fly faster than 1M without AB and they were not called "supercruisers". What I understand at the mark in the video you sent is that izd. 117 is a little short of specific thrust to match the 5th gen level (that reference being set by the F-22) in terms of speed, hence the "5th gen minus" classification by Lyulka

Now comparing a newly developed plane like Su-57 to a redesigned one like B-1 in terms of carrying over inherited solutions is another twisted argument. Is it so difficult to assume that Sukhoi worked rationally and the intake was deemed necessary either for current or future requirements? The plane does already fly faster than 2M on AB (that may be enough to force the development of the variable inlet, I don't know) and we simply don't know what is the max speed on mil power, either with first or second stage engines. But on F-22 it is close to the 2M mark already, while izd. 30 is considered "5th gen plus". I can see why it would be perfectly valid to force your opponent into AB while you can stay on mil as a way to rule the engagement, so maybe even small differences in speed at the lower end of the 2 < M < 3 window are worth investing on them.
 
icyplanetnhc (Steve) said:
I’m frankly being charitable here. Marchukov stated that the Su-57 with the AL-41F1 does not achieve supersonic cruise without afterburners. Given that the Su-35 with the AL-41F1S attained Mach 1.1 without afterburners, I presumed that the Su-57 is capable of achieving the same, and that supersonic cruise refers to speeds beyond transonic region (Mach 0.8-1.2), hence Mach 1.3 or so.
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Isn't it possible it might need afterburner to punch through the drag rise around Mach 1.0 but drag reduction above the transonic region could allow a certain degree of supercruise with afterburners off? I think that was suggested for the Eurocanards.
 
Some thoughts here:
1.) As Overscan said, pushing through the draggy transonic region might be meant here. Reportedly even F-22s do so, as it's more fuel efficient to briefly light up burners to pass the transonic region than spending a small eternity therein.

2.) Supercuise means supersonic CRUISE. Cruising is a fuel preserving flight condition. The way it was defined by the USAF for the ATF was the aircraft can cruise supersonically at a cruise settings, that's not full military (max non-afterburning) thrust setting! Most aircraft for which a "supercruise" capability is touted are no supercruisers at all. They can sustain supersonic flight at max dry settings and even pass the transonic region that way, but they cannot sustain higher supersonic speeds at a cruise setting. The F-22 reportedly maintains M 1.5 at ~90% dry thrust RPM.

3.) The Su-57 also being an interceptor doesn't make it the equivalent to the MiG-31, the Su-27 was an interceptor is well, like the MiG-23 etc. The MiG-31, like its ancestor MiG-25 were specifically designed to fly particularly high and fast and traded other performance characteristics, especially maneuverability/agility to achieve this. When the Su-57 replaces the MiG-31 then not on equal terms and only, if the PAK DP fails for whatever reasons, affordability being one possible reason.
 
LMFS said:
On the one hand you have Bogdan stating the big difference in acceleration of the Su-57 vs Su-35 and the need to take care to avoid going supersonic without noticing, then you don't exactly know what interpretation of "supercruising" Marchukov is referring to, since that term used to mean flying faster than 1.5M on mil power, when it was coined. Several legacy planes were known to be able to fly faster than 1M without AB and they were not called "supercruisers". What I understand at the mark in the video you sent is that izd. 117 is a little short of specific thrust to match the 5th gen level (that reference being set by the F-22) in terms of speed, hence the "5th gen minus" classification by Lyulka
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As far as I know, there has not been an official Russian definition of supercruise, and generally speaking supercruise refers to holding speeds above the transonic region (Mach 0.8-1.2) without afterburner. Mach 1.5 was simply the supercruise operating number that the ATF, the F-22, was optimized for, but generally, anything above Mach 1.2 would be considered supercruise. Perhaps with the AL-41F1, the Su-57 is around that upper Mach 1.2 boundary without afterburner, hence Marchukov’s comment about supercruise.

overscan (PaulMM) said:
Isn't it possible it might need afterburner to punch through the drag rise around Mach 1.0 but drag reduction above the transonic region could allow a certain degree of supercruise with afterburners off? I think that was suggested for the Eurocanards.
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Well, the context that Marchukov was talking about when when stating that the AL-41F1 being unable to allow the Su-57 to supercruise is insufficient specific thrust. To me this is more pertinent when discussing sustaining supersonic speeds rather than going through the transonic region. Using afterburner to accelerate through the draggy transonic region is quite normal even for supercruising aircraft that I don’t think it would be worth mentioning. The F-22 uses afterburners to punch through the transonic because even though it can go through without afterburners, the longer time required meant that it would use more fuel than just using afterburner to reach the desired supercruise speeds. The Concorde, which is among the fastest supercruising aircraft, also does this.
 
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icyplanetnhc (Steve) said:
Well, the context that Marchukov was talking about when when stating that the AL-41F1 being unable to allow the Su-57 to supercruise is insufficient specific thrust.
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He never said that.
I did transcript of his speech, up until moment where he began talking about detonation engines.

All he says about specific values (specific thrust at mil).
 
overscan (PaulMM) said:
Isn't it possible it might need afterburner to punch through the drag rise around Mach 1.0 but drag reduction above the transonic region could allow a certain degree of supercruise with afterburners off? I think that was suggested for the Eurocanards.
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I believe lockmart claims this for F-35 as well.
 
The parameter "maximum thrust / midship" is in some way related to the possibility of achieving cruising supersonic.
Su-57 - izd. 30
Su-57 - izd. 117 - 2306 kgs/m2
 

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Scorpion82 said:
2.) Supercuise means supersonic CRUISE. Cruising is a fuel preserving flight condition. The way it was defined by the USAF for the ATF was the aircraft can cruise supersonically at a cruise settings, that's not full military (max non-afterburning) thrust setting! Most aircraft for which a "supercruise" capability is touted are no supercruisers at all. They can sustain supersonic flight at max dry settings and even pass the transonic region that way, but they cannot sustain higher supersonic speeds at a cruise setting. The F-22 reportedly maintains M 1.5 at ~90% dry thrust RPM.
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Flying at supersonic speed makes no real sense for cruising, it is a high energy state related to combat and a substitute for dashing in AB that massively helps a plane dominate the engagement. Cruising should be done at min necessary throttle settings for range / endurance optimization, that is never going to be supersonic.

icyplanetnhc (Steve) said:
Perhaps with the AL-41F1, the Su-57 is around that upper Mach 1.2 boundary without afterburner, hence Marchukov’s comment about supercruise.
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Given the engine's characteristics and available thrust, that is what I would assume as a safe bet. It is not easy to quantify the difference in performance noted by Bogdan re. Su-35, it appeared to imply the plane can go supersonic without AB, but was not really specific
 
LMFS said:
Flying at supersonic speed makes no real sense for cruising, it is a high energy state related to combat and a substitute for dashing in AB that massively helps a plane dominate the engagement. Cruising should be done at min necessary throttle settings for range / endurance optimization, that is never going to be supersonic.
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It makes no sense in terms of just get from A to B in the most efficient flight regime. It makes sense, however, if you are operating in hostile airspace. Being gast, high and stealthy is a pretty good protection and passing some dangerous areas more quickly is also helpful.
 
LMFS said:
Flying at supersonic speed makes no real sense for cruising, it is a high energy state related to combat and a substitute for dashing in AB that massively helps a plane dominate the engagement. Cruising should be done at min necessary throttle settings for range / endurance optimization, that is never going to be supersonic.
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For engines optimized for supersonic flight, it creates a second range optimum (and in the past there were planes for which it was the single optimum, them being so inefficient at subsonic cruise it just didn't pay off).
For F-22, supersonic flight is quite efficient range-vise, for example - the limitation comes IIRC from temperature limitations, not fuel/efficiency.
 
Scorpion82 said:
It makes no sense in terms of just get from A to B in the most efficient flight regime. It makes sense, however, if you are operating in hostile airspace. Being gast, high and stealthy is a pretty good protection and passing some dangerous areas more quickly is also helpful.
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Combat oriented in any case, be it A2A or A2G. In A2G missions the AD footprint is severely reduced by the altitude and speed of the target and this is aggravated by its low RCS, plus the turnaround times are reduced and range of the launched weapons increases. Of course supersonic maneuverability is a crucial parameter here (not the strongest point in the MiG-31 for instance) and the Su-57 has been explicitly designed with that goal in mind.
Ainen said:
For engines optimized for supersonic flight, it creates a second range optimum (and in the past there were planes for which it was the single optimum, them being so inefficient at subsonic cruise it just didn't pay off).
For F-22, supersonic flight is quite efficient range-vise, for example - the limitation comes IIRC from temperature limitations, not fuel/efficiency.
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F-22 has rather short legs and from what I recall the supercruising range in a given mission is estimated in some hundreds of miles. For the Su-57 a supersonic range of more than 1500 km has been indicated. In any case this is three times less than maximum range on internal fuel of >3500 km
 
paralay said:
MiG-31 2500 km/h (M=2.35), 625 km
Su-57
1400 km/h (M=1.3), 1400 km (ed.117)
1900 km/h (M=1.78), 1900 km (ed.30)
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Rather doubtful that the Su-57 can fly much faster with AL-51 and still burn the same amount of fuel as with AL-41. I keep it for what it is, made up figures based on oversimplified reasoning.
 
Scorpion82 said:
Rather doubtful that the Su-57 can fly much faster with AL-51 and still burn the same amount of fuel as with AL-41. I keep it for what it is, made up figures based on oversimplified reasoning.
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I second that. It just sound wrong..

And how much fuel does the Mig-31 Carry. around 16.000kg?
It should give fuel for thoughts..
 
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So what does the mig-31 bring to the table that the su-57 doesn’t? Faster acceleration and time to altitude? Multi crew to reduce workload? Longer range?
 
AGS-1787 said:
So what does the mig-31 bring to the table that the su-57 doesn’t? Faster acceleration and time to altitude? Multi crew to reduce workload? Longer range?
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Much higher operating altitude, much higher top speed, much higher cruising speed, much bigger antenna aperture
 
(c)KCNA
 

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I don't know The Su-57 similar like 01Su-57 on Desember 2020 if see the Pitot , but After than Pitot was remove on next production
 

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sputnikglobe.com

Su-57 Unleashed: Rostec Powers Up Jet With Game-Changing Stage 2 Engine

The combat capabilities of the Su-57 fifth-generation fighter are increasing as it is being upgraded and is now equipped with the second stage engine (Saturn AL-51F-1, codenamed "Izdeliye 30"), the Rostec State Corporation press service said.
sputnikglobe.com sputnikglobe.com

"The state-owned company said the fighter is undergoing flight tests with the second-stage engine and it plans to deliver the aircraft with the new engine under the existing production contract."

Huge and awesome if true. I wonder if the newest two dimensional nozzle iteration is going to be seen.
 
paralay said:
Do you think that purchasing decisions are made on the basis of a poster? :)
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Considering the YF-22 in part won through cool imagery of missile launches I would say yes cool posters and Top Trumps boards can sway non-technical people and they tend to be the ones in charge of the money and paperwork!
 

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