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Sukhoi Su-57 / T-50 / PAK FA - flight testing and development Part II

LMFS

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New missile inside internal bays
by paralay of course
Well seen by paralay, if the lattice fins are thin enough (doesn't seem the case in the pictures) and since apparently no lifting strakes are used, it may be possible to place four missiles side-by-side in each bay, for a total potential loadout of 16 missiles... The length seems a bit problematic though, since the grey shadowed area of the bays is in principle not available (a physical wall necessary to reduce turbulence when opening the doors if I am not wrong). Maybe the nose is shorter, with an IR seeker? The placement of the missiles could be improved a bit but nevertheless with the length he has calculated they don't seem to fit... but they should, otherwise I don't understand a thing about these new missiles o_O

It would also be interesting to know how that aero arrangement would work to generate lift (and hence turning ratio) at different altitudes. That should allow to understand what their use should be.
 

FighterJock

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New missile inside internal bays
by paralay of course
Well seen by paralay, if the lattice fins are thin enough (doesn't seem the case in the pictures) and since apparently no lifting strakes are used, it may be possible to place four missiles side-by-side in each bay, for a total potential loadout of 16 missiles... The length seems a bit problematic though, since the grey shadowed area of the bays is in principle not available (a physical wall necessary to reduce turbulence when opening the doors if I am not wrong). Maybe the nose is shorter, with an IR seeker? The placement of the missiles could be improved a bit but nevertheless with the length he has calculated they don't seem to fit... but they should, otherwise I don't understand a thing about these new missiles o_O

It would also be interesting to know how that aero arrangement would work to generate lift (and hence turning ratio) at different altitudes. That should allow to understand what their use should be.
I wonder how accurate paralay's load out is for the Su-57, I have seen many different versions some with four missiles and some with six missiles over the two weapons bay's it all makes it rather confusing to say the least. :confused:
 

stealthflanker

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It would also be interesting to know how that aero arrangement would work to generate lift (and hence turning ratio) at different altitudes. That should allow to understand what their use should be.
Body lift.

The missile may have like half of its weight dedicated to rocket motor, since the dimension is quite evident (2 m class and 20 cm diameter) One can resonably guess launch weight to be at something like 88.6 Kg. Assuming 40 Kg of it dedicated to propellant, L/D of 2 (reasonable for axisymmetric missile) and boost-glide profile it can reach like 60 Km.

As you see in image is my estimate on potential trajectory, assuming Mach 0.9 launch speed and 12000 m altitude
 

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Avimimus

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...but they should, otherwise I don't understand a thing about these new missiles o_O
It could be that they are meant for the WVR underwing bays (the ones that carry R-74 currently)...

However, I agree that it is tempting to imagine such weapons in the main bay... especially given the attempts to expand the magazine depth of the F-35/F-22 with double stacked launchers and the existing ability to carry two bombs in a similar layout within each half-bay...

However, if there isn't enough room for the weapons to be mounted side-by-side we'd still be talking about a doubling of the missiles carried in the main bays (i.e. from 4 to 8)...

I wonder how accurate paralay's load out is for the Su-57, I have seen many different versions some with four missiles and some with six missiles over the two weapons bay's it all makes it rather confusing to say the least. :confused:
I always took it to be guesswork... clever guesswork often... optimistic guesswork sometimes...
 

Avimimus

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It would also be interesting to know how that aero arrangement would work to generate lift (and hence turning ratio) at different altitudes. That should allow to understand what their use should be.
Body lift.

The missile may have like half of its weight dedicated to rocket motor, since the dimension is quite evident (2 m class and 20 cm diameter) One can resonably guess launch weight to be at something like 88.6 Kg. Assuming 40 Kg of it dedicated to propellant, L/D of 2 (reasonable for axisymmetric missile) and boost-glide profile it can reach like 60 Km.

As you see in image is my estimate on potential trajectory, assuming Mach 0.9 launch speed and 12000 m altitude
Thanks! That analysis is appreciated.
 

LMFS

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I wonder how accurate paralay's load out is for the Su-57, I have seen many different versions some with four missiles and some with six missiles over the two weapons bay's it all makes it rather confusing to say the least. :confused:
I always assumed, to be on the safe side, the MRAAM loadout would be 4 pieces in total, while he has proposed a configuration with 6, 3 per bay. For this, all the three pylons would need to be in positions different to those used for carrying the bigger weapons of roughly 0.4 m diameter, of which only two units can be carried per bay. Judging by the pylons on the pictures, they are simply bolted to the plane, so, why not to make provisions for this alternative layout and allow the extended missile load? I currently see nothing that prevents his proposal from being at least a possibility.

Body lift.

The missile may have like half of its weight dedicated to rocket motor, since the dimension is quite evident (2 m class and 20 cm diameter) One can resonably guess launch weight to be at something like 88.6 Kg. Assuming 40 Kg of it dedicated to propellant, L/D of 2 (reasonable for axisymmetric missile) and boost-glide profile it can reach like 60 Km.

As you see in image is my estimate on potential trajectory, assuming Mach 0.9 launch speed and 12000 m altitude
Thanks for the analysis. Two questions:
- Wouldn't the lattice fins affect that L/D you estimate?
- Are you sure regarding that flight profile? Normal lofted trajectories I have seen look different, with a less marked climb at the beginning. For this one of yours I am left wondering what the resulting flight speeds would be.

It could be that they are meant for the WVR underwing bays (the ones that carry R-74 currently)...
Maybe, but then, why to make them shorter than the R-73, and what would be the advantage of the new missile?
However, I agree that it is tempting to imagine such weapons in the main bay... especially given the attempts to expand the magazine depth of the F-35/F-22 with double stacked launchers and the existing ability to carry two bombs in a similar layout within each half-bay...

However, if there isn't enough room for the weapons to be mounted side-by-side we'd still be talking about a doubling of the missiles carried in the main bays (i.e. from 4 to 8)...
Just entertaining theories:

Are these shorter ranged missiles the way 5G fighters are expected to fight each other in the end, or rather countermeasures? Inside an IADS longer detection ranges are to be expected, but still engagements usually do not take place at extreme distances, and even then pk of missiles against modern fighters seems quite low on far shots. A missile of this kind would allow a plane to continue its mission despite being under attack by actively destroying incoming AAMs (those that pose a risk, since high, fast flying Su-57 would by itself be difficult to shoot down). This may seriously reinforce the Su-57's air superiority capabilities, supported by very big WBs, long range, remarkable maneuverability and high/fast cruising. So to say, would allow the plane to close in on any predetermined target, relying on high speed, long legs, defensive resources and ultimately manouvering combat prowess.

For the interceptor role, a big number of missiles would also be interesting and allow to multiply the effectiveness of the existing aircraft, specially against swarm / saturation attacks.

Those clearances look questionable and overly optimistic. I highly doubt that each bay can fit 4 missiles abreast of each other.
Would you care elaborating? Maybe there is no direct comparison due to different release speeds or other reasons, but the SDBs in the bays of F-22/F-35 are really tightly packed, more even than the missiles in the proposal above, without that being apparently a problem. On top of that, we still don't know the exact measures of the bays in the Su-57.
 

stealthflanker

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Thanks for the analysis. Two questions:
- Wouldn't the lattice fins affect that L/D you estimate?
- Are you sure regarding that flight profile? Normal lofted trajectories I have seen look different, with a less marked climb at the beginning. For this one of yours I am left wondering what the resulting flight speeds would be.
I would say the effect wont be too much as the fin might only move little bit and locked during the apogee. It will start make matters at endgame when it determine maneuverability. In fact it is very conservative as for axisymmetric you can actually have L/D max of 3. But i use 2 to take account for possibility that L/D might change along the flight and cannot be compensated by the guidance.

and i am very sure about that flight profile. It does not really like the "smooth" curve of the Ballistic profile of the 5V55 missile but that's just what happen when you only have few points of data yielded from the equations. You can google up trajectory estimates methodology by E.Fleeman in his missile design course and you will find similar trajectory plot.

The speed profile of the missile are as follows :
At the end of boost phase : M 5.6 and altitude of 15562 m
The missile continue to climb unpowered until its apogee at 27800 m, at this stage the missile velocity is M 3.7
The missile proceed to glide down to target altitude of 12000 m at the end of the glide/endgame the missile's velocity is M 1.2
 

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icyplanetnhc

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Those clearances look questionable and overly optimistic. I highly doubt that each bay can fit 4 missiles abreast of each other.
Would you care elaborating? Maybe there is no direct comparison due to different release speeds or other reasons, but the SDBs in the bays of F-22/F-35 are really tightly packed, more even than the missiles in the proposal above, without that being apparently a problem. On top of that, we still don't know the exact measures of the bays in the Su-57.
The packing of the AMRAAMs in the F-22's bays is not nearly as tight as with the SDBs. Furthermore, the width of the Su-57 bay is not much greater than each of the F-22's main bay, so I'm skeptical of mounting an additional (larger diameter) missile abreast. One needs to also consider bulkhead "ribs" that may protrude into the bay and also door clearances. Weapons carriage isn't as simple as seeing what you can get away using the cardinal dimensions and using some arbitrary margins.
 
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stealthflanker

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Well according to Raymer, regarding weapon mountings, clearence for weapons should be at least 3 inches (7.62 cm). Furthermore for fall down type weapon there has to be 10 degrees "cone of clearance" between the weapon and any part of the aircrafts as well as its launch path.

I wonder however if Paralay take those into account or there is another regulations/rules regarding weapon clearance for VVS. If he does take account of that then 16 weapons in Su-57 weapon bay can be real.
 

LMFS

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I would say the effect wont be too much as the fin might only move little bit and locked during the apogee. It will start make matters at endgame when it determine maneuverability. In fact it is very conservative as for axisymmetric you can actually have L/D max of 3. But i use 2 to take account for possibility that L/D might change along the flight and cannot be compensated by the guidance.
I hoped to find some CFD analysis by user "litzj" (http://jaesan-aero.blogspot.com/), but he didn't do R-77. In any case the shockwaves at the lattices may cause interference if the speed range is very wide (like in your case from 5.6 to 1.2 M), a detailed analysis would be needed. From what I see it is normally assumed that the reduced range of the R-77 vs. the AMRAAM is mainly due to drag and flight profile issues.

and i am very sure about that flight profile. It does not really like the "smooth" curve of the Ballistic profile of the 5V55 missile but that's just what happen when you only have few points of data yielded from the equations. You can google up trajectory estimates methodology by E.Fleeman in his missile design course and you will find similar trajectory plot.

The speed profile of the missile are as follows :
At the end of boost phase : M 5.6 and altitude of 15562 m
The missile continue to climb unpowered until its apogee at 27800 m, at this stage the missile velocity is M 3.7
The missile proceed to glide down to target altitude of 12000 m at the end of the glide/endgame the missile's velocity is M 1.2
Thanks for explaining and for the sources, I think you are right. I saw analysis from Spurts at F-16.net with the profile you see below, but in the end I guess it makes sense to spend the propellant to get potential energy and get faster to the less dense atmosphere layers rather than consuming it fighting drag at increased speeds and in thicker air.

Well according to Raymer, regarding weapon mountings, clearence for weapons should be at least 3 inches (7.62 cm). Furthermore for fall down type weapon there has to be 10 degrees "cone of clearance" between the weapon and any part of the aircrafts as well as its launch path.

I wonder however if Paralay take those into account or there is another regulations/rules regarding weapon clearance for VVS. If he does take account of that then 16 weapons in Su-57 weapon bay can be real.
See the SDBs, they are placed a bit more than 1 inch apart. As a general rule I understand all those comments, but in the end you need a detailed quantitative work and testing to establish release envelope, so we cannot know with certainty.

The packing of the AMRAAMs in the F-22's bays is not nearly as tight as with the SDBs. Furthermore, the width of the Su-57 bay is not much greater than each of the F-22's main bay, so I'm skeptical of mounting an additional (larger diameter) missile abreast. One needs to also consider bulkhead "ribs" that may protrude into the bay and also door clearances.
Well, the AIM-120 have fins, so they cannot be placed much tighter than they are already.
Weapons carriage isn't as simple as seeing what you can get away using the cardinal dimensions and using some arbitrary margins.
Sure! But the incentive to increase the missile load is clear I think, so manufacturers will work in great detail to extract the most from their bays. We will see how future improvements in this area look like, but SDBs, CUDAs, optimization in the F-35 for 6x AMRAAM, Kh-59MK2 among others are already showing the way towards reduced clearances and weapons specifically designed for internal carriage.
 

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Trident

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The lattice fins choking with shock waves is only a problem in the transonic range IIRC. At high (and also subsonic - see Klub/Kalibr booster or MOAB/MOP) Mach their drag characteristics should be good. You could perhaps argue that in this regard the assumed Mach 1.2 terminal speed is a tad optimistic and should be increased somewhat (= shorter effective range) for adequate end-game agility.
 

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We know that there are single munition launchers and launchers for two munitions (stacked one behind the other). So it'd seem safest to assume one long range missile (up to 700kg) or two of these short missiles per door.
 

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It looks like a cut down R77. Shortened rocket motor and added TVC. Foreend is copy & paste, until red section (rocket motor) starts. It looks as well a booster could be added. The housing and the wire tray end like there could be added something. So maybe a WVR 1-stage and BVR 2-stage system?

Further interesting are the windows in the strake of the R-77 version. For aerodynamic reasons?
 
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panzerfeist1

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Wow ... but isn't this a bit low and how many are planned to be certified?
This sounds like 1 test per month since the engines introduction. All I got to say is art cant be rushed. I am guessing that after each flight test duration they analyze the engines, see if changes have to made in, what results the modifications would bring, etc. I also have no idea how much would be certified with the newer engines.
 

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Hmmmm... According to Gerasimov (head of General Staff of Russia) T-50 at some point was deployed it Syria second time. Interesting when...
 

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Hmmmm... According to Gerasimov (head of General Staff of Russia) T-50 at some point was deployed it Syria second time. Interesting when...
No doubt we will find out when and how many Su-57's were in Syria in due course.
 

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I hope the pilot ejected and is okay. It is not good news for the Su-57.
 

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Do we have any confirmation that it was the first serial airframe?
 

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Months imho. And I hope they won't rush it, cuz second one should work perfectly
 

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Do we have any confirmation that it was the first serial airframe?
Yes. There was nothing else Su-57/T-50 related to crash out of KnAAZ anyway.

How long you think it will hold the delivery of the 2nd serial ?
It is still very early in build process. Looks like end of next year, by some miracle might be summer, but a long way off either way.
 

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If they changed the FCS software at some point and didn't validate the new version properly, I suppose a software failure is possible. That was one aspect where the programme seemed to be doing really well though, with remarkably quick envelope expansion after first flight and some rather challenging test scenarios (didn't they fly it with only one tail fin to verify damage tolerance at one point?).

Actuator hard-over?
 

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It would be hard to speculate without much elements but the fact that they identify the FCS as failing and the plane going down 100km from its base would seem to be ambivalent. A mechanical failure could be more damaging in term of sales potential (remember how India pulled out earlier after an engine fire). There could be some incentive to hide such behind something like an FCS failure that won't need any component change but only a bit of programming.
 

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What "not again"? India expressed publicly their doubts for the program after this incident.
 

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They expressed "doubts" since day 1 because wanted discount on tech transfer. When they were finally redused yet anothet time - plane became " very-very bad"
 

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If they changed the FCS software at some point and didn't validate the new version properly, I suppose a software failure is possible. That was one aspect where the programme seemed to be doing really well though, with remarkably quick envelope expansion after first flight and some rather challenging test scenarios (didn't they fly it with only one tail fin to verify damage tolerance at one point?).

Actuator hard-over?
Yes, I was impressed by that too. It is easy to imagine such ambition having some costs. However, it could also just be that someone screwed up with wiring or testing some component...

They expressed "doubts" since day 1 because wanted discount on tech transfer. When they were finally redused yet anothet time - plane became " very-very bad"
Yes, it is more complex.
 

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However, it could also just be that someone screwed up with wiring or testing some component..
This is orders of magnitude more probable. Noone is gonna test new software parts on LRIP airframe during it first flights. There are more than enough prototypes for that.
 
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