Sukhoi Su-57 / T-50 / PAK FA - flight testing and development Part I [2010-2012]

[Wil]

Hello Boys!

Nothing new, just a size comparison between the Su-27, Mig-29, F-22 and the PAK FA. Copyright in the image.

 

[N22YF]

It was probably too difficult/expensive to redesign the existing Su-30 airframe when TVC was integrated.

Very difficult to reduce the size of the vertical tails indeed.

What I meant to say is, it was probably not worth the cost/effort to redesign the Su-30 tails (especially since LO wasn't a concern, although I doubt that any significant vertical stabilizer reduction would have been possible anyway, since the Su-30MKI doesn't have much yaw vectoring capability).
Also I think redesigning the Su-30 with smaller tails might have been pretty ambitious, since designing fighters with small tails compensated for with TVC was pretty cutting-edge then. (I believe the X-36 was the first fighter design to fly with this configuration, and that was about the same time as the Su-30MKI's first flight and after the Su-37's first flight.)

TVC is more of an enhancement, with aerodynamic controls alone still being sufficient. However, this does not mean you cannot reduce or eliminate tails if you're using TVC (again, look at the X-36).

I agree 100% but X-36 is an experimental aircraft, just like the X-29. It is a testbed, not an flying proof that using TVC to replace tails is a practical solution at the moment. Forward swept wings also looked good on paper but never made it mainstream. Suchoi, totally waisted their time and money with this technology. Now they should just rely on the US experience with its 2 trust vector programs and implement the technology in similar fashion.

Well McDonnell Douglas had enough faith in the merits of this configuration to use it on their JSF proposal (which says a lot, given the importance of the JSF to MD); I don't think FSW on fighters has ever been validated to this level.

 

[Sundog]

We have plenty of validation on FSW. They simply don't offer enough advantages over conventional wings to offset their drawbacks. If you are going to limit speed to less than M=1.7 they can do OK, but above that, they pay a weight penalty compared to conventional/rear swept wings. Plus, mounting weapons/drop tanks on them is more problematic as well. The main reason for FSW wings wrt conventional wings, was their performance advantage at high AOA. However, with the advanced FCS and aerodynamics we use today, the FSW doesn't actually confer any real useful advantages anymore.

Now, back OT: Have there been any more flights of the T-50 lately?

 

[Spring]

We have plenty of validation on FSW. They simply don't offer enough advantages over conventional wings to offset their drawbacks. If you are going to limit speed to less than M=1.7 they can do OK, but above that, they pay a weight penalty compared to conventional/rear swept wings. Plus, mounting weapons/drop tanks on them is more problematic as well. The main reason for FSW wings wrt conventional wings, was their performance advantage at high AOA. However, with the advanced FCS and aerodynamics we use today, the FSW doesn't actually confer any real useful advantages anymore.

Now, back OT: Have there been any more flights of the T-50 lately?

You are terribly wrong, i must say that at first i was thinking like you, until i got some online NASA studies.

The X-29 with less T/W, less wing area, being just a demonstrator, with out a full combat optimized aerodynamics, did perform better than a F-15,16 or 18, for acceleration height performance and sustained turn and combined profile/maneuvers.

Real performance is not shown in airshows, the profile for the FSW program was aimed to get a mix of the best of the F-104 and the best of the Su-27/Mig-29, something that it can't be achieved unless the T/W ratio would be increased...and even yet i doubt there is an aircraft with such combined features.

Not everything is fixed with computers, composites and smoother profiles, look at the naval variants for the ATF proposals, one had a variable geometry wing, the other had a horrible immense aspect wing ratio (even more than the F-18), computers or FBW don't generate lift

Look at the F-35C

The deal with the X-29 was to achieve the same with a weaker engine and less wing area, that should decrease the drag and weight, was meant to test the efficiency for such configuration...and given the data, it was very, very efficient., doing this with a high aspect wing, that would have low drag at supersonic speeds...and probably (or most likely) had solved the typical problems between high speed requirements, and low speed handling (that are not solved yet), what is more intelligent the VG wing or the FSW wing?

Now;

The wing load of the X29 was 450kg/m2
The wing load of the S-37 is 250kg/m2

Now you can imagine how good the Berkut was meant to be...

The russians did know how great concept was the FSW, but they went lazy, they threw in the towel , anyways..the Raptor was not a great and revolutionary aircraft, so why to bother with an advanced S-37? , why to bother to fix all the structural issues of the FSW concept?... fit on the new plane more powerful engines, or just don't do the same weight control mistakes the LM team did, and everything will be OK.

The FSW had future, is just that, the 5th generation is not that great, and the cold war is over.

The S-37 is not an airshow plane, is under testing developing and even modification, the plane is being used for experimenting, the russians know the FSW concept works, and need more development.

Probably they even considered it for the 5th gen program, since there is a model of a faceted s-37 out there...why to bother with a 'failed' configuration?

Somehow, i think Sukhoi considers the S-37, the 6th gen aircraft, they are keeping it alive, after 10 years..or more...is not for 'pride' or to show how nice looking is.

 

[Gavin]

The prevalent assumption is that the PAK-FA will incorporate 3D TVC, indicated by the reduced - albeit all-moving - stabs. A 2D nozzle perhaps doesn't fit too well with this notion.

B. Bolsøy/Oslo

Are the vertical tails really that short? Perhaps not as much as they first appear. In this size comparison, the T-50 verticals are indeed noticeably shorter than the others, but not dramatically so.

 

[BDF]

The scale looks off for the YF-23. Maybe I'm wrong but it appears to me that the YF-23 is just a tad small. Theres about a 1 foot difference between the F-22A's and the YF-23's wingspan and it appears to be more in this graphic.

 

[Sundog]

You are terribly wrong, i must say that at first i was thinking like you, until i got some online NASA studies.

The X-29 with less T/W, less wing area, being just a demonstrator, with out a full combat optimized aerodynamics, did perform better than a F-15,16 or 18, for acceleration height performance and sustained turn and combined profile/maneuvers.

Real performance is not shown in airshows, the profile for the FSW program was aimed to get a mix of the best of the F-104 and the best of the Su-27/Mig-29, something that it can't be achieved unless the T/W ratio would be increased...and even yet i doubt there is an aircraft with such combined features.

Not everything is fixed with computers, composites and smoother profiles, look at the naval variants for the ATF proposals, one had a variable geometry wing, the other had a horrible immense aspect wing ratio (even more than the F-18), computers or FBW don't generate lift

Look at the F-35C

The deal with the X-29 was to achieve the same with a weaker engine and less wing area, that should decrease the drag and weight, was meant to test the efficiency for such configuration...and given the data, it was very, very efficient., doing this with a high aspect wing, that would have low drag at supersonic speeds...and probably (or most likely) had solved the typical problems between high speed requirements, and low speed handling (that are not solved yet), what is more intelligent the VG wing or the FSW wing?

Now;

The wing load of the X29 was 450kg/m2
The wing load of the S-37 is 250kg/m2

Now you can imagine how good the Berkut was meant to be...

The russians did know how great concept was the FSW, but they went lazy, they threw in the towel , anyways..the Raptor was not a great and revolutionary aircraft, so why to bother with an advanced S-37? , why to bother to fix all the structural issues of the FSW concept?... fit on the new plane more powerful engines, or just don't do the same weight control mistakes the LM team did, and everything will be OK.

The FSW had future, is just that, the 5th generation is not that great, and the cold war is over.

The S-37 is not an airshow plane, is under testing developing and even modification, the plane is being used for experimenting, the russians know the FSW concept works, and need more development.

Probably they even considered it for the 5th gen program, since there is a model of a faceted s-37 out there...why to bother with a 'failed' configuration?

Somehow, i think Sukhoi considers the S-37, the 6th gen aircraft, they are keeping it alive, after 10 years..or more...is not for 'pride' or to show how nice looking is.

Having actually designed an aircraft with an FSW, I'm actually not wrong as I recall the problems we ran into with our design. If it was as good as you thought it was it would be on a production aircraft. It isn't. Sukhoi studied it and abandoned it because it didn't meet the requirements for the PAK-FA. Aerospace Engineers aren't lazy and dumber than the fanboys. The majority of them do their jobs well, which is why you don't see a FSW in production.

 

[Spring]

You should read the NASA reports on the 29's performance

Sukhoi studied it and abandoned it because it didn't meet the requirements for the PAK-FA. Aerospace Engineers aren't lazy

Probably i selected a wrong word.

But for the russians there was no reason to develop a radical design

Time and money, they had came too late in the market

If it was as good as you thought it was it would be on a production aircraft

But it had problems of course, the FSW shown that was more efficient than a conventional wing for the same wing area, this is very important, and that's why russians are sill researching the FSW concept..unless you think is a PAKFA 'demonstrator'...which is not.

 

[sferrin]

You are terribly wrong, i must say that at first i was thinking like you, until i got some online NASA studies.

The X-29 with less T/W, less wing area, being just a demonstrator, with out a full combat optimized aerodynamics, did perform better than a F-15,16 or 18, for acceleration height performance and sustained turn and combined profile/maneuvers.

Real performance is not shown in airshows, the profile for the FSW program was aimed to get a mix of the best of the F-104 and the best of the Su-27/Mig-29, something that it can't be achieved unless the T/W ratio would be increased...and even yet i doubt there is an aircraft with such combined features.

Not everything is fixed with computers, composites and smoother profiles, look at the naval variants for the ATF proposals, one had a variable geometry wing, the other had a horrible immense aspect wing ratio (even more than the F-18), computers or FBW don't generate lift

Look at the F-35C

The deal with the X-29 was to achieve the same with a weaker engine and less wing area, that should decrease the drag and weight, was meant to test the efficiency for such configuration...and given the data, it was very, very efficient., doing this with a high aspect wing, that would have low drag at supersonic speeds...and probably (or most likely) had solved the typical problems between high speed requirements, and low speed handling (that are not solved yet), what is more intelligent the VG wing or the FSW wing?

Now;

The wing load of the X29 was 450kg/m2
The wing load of the S-37 is 250kg/m2

Now you can imagine how good the Berkut was meant to be...

The russians did know how great concept was the FSW, but they went lazy, they threw in the towel , anyways..the Raptor was not a great and revolutionary aircraft, so why to bother with an advanced S-37? , why to bother to fix all the structural issues of the FSW concept?... fit on the new plane more powerful engines, or just don't do the same weight control mistakes the LM team did, and everything will be OK.

The FSW had future, is just that, the 5th generation is not that great, and the cold war is over.

The S-37 is not an airshow plane, is under testing developing and even modification, the plane is being used for experimenting, the russians know the FSW concept works, and need more development.

Probably they even considered it for the 5th gen program, since there is a model of a faceted s-37 out there...why to bother with a 'failed' configuration?

Somehow, i think Sukhoi considers the S-37, the 6th gen aircraft, they are keeping it alive, after 10 years..or more...is not for 'pride' or to show how nice looking is.

Having actually designed an aircraft with an FSW, I'm actually not wrong as I recall the problems we ran into with our design. If it was as good as you thought it was it would be on a production aircraft. It isn't. Sukhoi studied it and abandoned it because it didn't meet the requirements for the PAK-FA. Aerospace Engineers aren't lazy and dumber than the fanboys. The majority of them do their jobs well, which is why you don't see a FSW in production.

I remember reading about an interview with an "old salty" aero engineer in which he was saying FSWs weren't all they were cracked up to be. The interviewer pointed out the X-29 and the engineer chuckled and said "yeah, we have to drag it out (the FSW) every 40 years or so to remind us why it's such a bad idea".

 

[overscan (PaulMM)]

You should read the NASA reports on the 29's performance

Sundog is an engineer, who has worked on an FSW design. What are your credentials that make your opinion on FSW worth listening to over that? Reading some NASA reports from the 1980s does not give you some special insight into FSW pros and cons.

Berkut had structural issues and the FSW was not attractive for PAK FA, I think that says it all really.

 

[overscan (PaulMM)]

I would also note we are straying far from the topic.

 

[Spring]

You should read the NASA reports on the 29's performance

Sundog is an engineer, who has worked on an FSW design. What are your credentials that make your opinion on FSW worth listening to over that? Reading some NASA reports from the 1980s does not give you some special insight into FSW pros and cons.

Berkut had structural issues and the FSW was not attractive for PAK FA, I think that says it all really.

I'm not pushing this to a 'fight of credentials'...i'm suggesting him, he should read the NASA's documents where they compare the x-29's lift excess, turning rate, acceleration with data from F-16,15,18.

Berkut had structural issues and the FSW was not attractive for PAK FA, I think that says it all really.

You don't understand it, yes this was the problem, at least is the one that was reported, but is not a real no-no for the concept, it just shows that the technology was not advanced enough to make it work.

 

[Stargazer]

Courtesy of Jschmus on the What If forum, here's a brand new photo of the T-50 from airliners.net:

http://www.airliners.net/photo/Sukhoi/Sukhoi-T-50/1699085/L/

 

[saintkatanalegacy]

hmmm... flat nozzle on PAK-FA

just some speculative half baked render

 

[donnage99]

I think the case for FSW is the same as canard delta wing. These configurations undeniably bring advantages in term of aerodynamic over conventional design, but agility isn't everything to building a lethal fighter. What about RCS, for example? And even it solves the structure problems, will it be a maintainance nightmare due to high strain on the wings over its life? Will it compromise sensor loadout or weapon loadout?

 

[flateric]

Stop non-T-50 discussion here please. If you want (all over again) discuss FSW and C-37 in particular, we have appropriate topics.

 

[Jackonicko]

On April 08, 2010, 03:37:58 pm, on the first page, 'Flanker' asked:

"What is the flight dates so far? have i got this correct?

1 - 29'th January.
2 - 6'th February
3 - 12'th February
4 - 25'th March
5 - 26'th March
6 -"

Any answer?

 

[flateric]

Not so far. I remember of your request. Initially sixth flight was scheduled for March, 29, but seems date was re-scheduled as initial dates for fourth and fifth flights were moved somewhat forth. Prior actual event, flights schedule remains a classified info.

 

[flanker]

Not so far. I remember of your request. Initially sixth flight was scheduled for March, 29, but seems date was re-scheduled as initial dates for fourth and fifth flights were moved somewhat forth. Prior actual event, flights schedule remains a classified info.

Okei, thanks for the info, will note it down.

 

[Matej]

The scale looks off for the YF-23. Maybe I'm wrong but it appears to me that the YF-23 is just a tad small. Theres about a 1 foot difference between the F-22A's and the YF-23's wingspan and it appears to be more in this graphic.

YF-22A, YF-23A and F-22A are exactly to the scale. T-50 is the best available guess at that time. When comparing the size of the tail surfaces, it is not very good to compare only the front view - what counts is the whole shape. Remember that when you double the size of the square, the surface is four times bigger (and such).

 

[mz]

http://www.google.com/patents?id=1_obAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false This Northrop patent by Wainfan is interesting as it's, overly simplified, a lerx / strake foresurface drooping for more low speed lift.

 

[Wil]

Hello Boys!

A new determination of PAK FA length:



The value found is ~20.00 m, but this number is provisional!

 

[flateric]

'51' performed second flawless flight at LII today with TO at 14.40 am MSK

 

[mr.sukhoi]

can u give us the source of that?

 

[flateric]

whitness at place would sound OK for you?
T-50 use callsign '125'
landing at ~16.15 AM MSK

 

[flateric]

Photo by Sergey Lysenko/RussianPlanes.Net

 

[Sundog]

Beautiful pic, Flateric.

BTW, did they also move the second prototype there? Any idea when it's supposed to fly? Or are they currently putting more systems in it for testing? Granted, I'm sure they aren't being too open about what is going on there, but JIC anyone knows...

 

[lancer21]

whitness at place would sound OK for you?
T-50 use callsign '125'
landing at ~16.15 AM MSK

You 'be been THERE ? You lucky ... ;D I envie you , seriously...
1h35min flight , quite long isnt it ? Anyway , nice angle in that pic, thanks.

To Sundog : well as far as i can make out from following various places around , second prototype is suposed to fly at the end of 2010 or beggining 2011...maby the russian peoples know more about this tho...

 

[flateric]

I wasn't there
second prototype is at LII, too, but it's non-flightworthy KNS testbed
you must not thank me for the photos as I did not take it, that was clearly stated

 

[lancer21]

Err...i was just thanking you for posting the pic here ,obviously my gratitude goes to S.Lysenko aswell. ( he's the lucky ...then ! )

 

[Sundog]

I wasn't there
second prototype is at LII, too, but it's non-flightworthy KNS testbed
you must not thank me for the photos as I did not take it, that was clearly stated

No, you posted it here and brought it to my attention; That's what you're being thanked for. If the photographer wishes to show up here, I'll think him as well.

 

[lancer21]

Nice new pic from Paralay's site (c) ASH...

http://paralay.iboards.ru/download/file.php?style=12&id=10580&mode=view

 

[QuadroFX]

Photos by Alexey Miheev:
http://www.take-off.ru/index.php/news/94-may-2010/469-t-50-14-05-2010

 

[saintkatanalegacy]

absolutely amazing shots specially on the top portion and front

 

[lancer21]

Here's another one , best quality from this flight so far (C) Sergey Lysenko
http://russianplanes.net/ID20386

 

[lancer21]

hmmm... flat nozzle on PAK-FA

just some speculative half baked render

Is this made by you ,or you found it somehwere? Would be very interesting to see the end result ,with the levcons ,wings and fins attached and offcourse the flat nozzles...

 

[sferrin]

Photos by Alexey Miheev:
http://www.take-off.ru/index.php/news/94-may-2010/469-t-50-14-05-2010

Any chance of higher rez?

 

[flateric]

they are actually larger than it seems...
weather was not quite good this day, so high ISOs and murky shots even with Aleksey's Canon EF 500mm f/4.0 L IS USM
moreover, T-50 photos still remains hot-sellers, so don't forget of commercial side

but this is not last flight...

 

[lancer21]

http://spotters.net.ua/file/?id=29394

 

[flanker]

Photos by Alexey Miheev:
http://www.take-off.ru/index.php/news/94-may-2010/469-t-50-14-05-2010

Any chance of higher rez?

Right click the pictures, paste the link, and voila, higher res.