PAK-FA and FGFA Thread

Cain Marko · Post by **Cain Marko** » 30 Apr 2010 10:42

b_patel wrote:
I got this image off of KeyPub, the highlighted regions are pretty much weapons bays for short range missiles. If you look at the non-zoomed bay on the right it looks like you can see the line for the weapons bay door. I definitely looks like it from this angle. Originally i thought it might be for additional EW equipment. But the additional weapons bay is a much better use for the space. What do you guys think?

Quite frankly, I don't see why they keep mention a SRAAM, the bay looks large enough to manage an R-77.

CM

Gaur · Post by **Gaur** » 01 May 2010 01:12

Some more pics of PAK-FA:

Indranil · Post by **Indranil** » 01 May 2010 01:18

What a meaty and broad fuselage! Should have enormous lift!

Looking at the plane from the side and the bottom, I don't feel that the inside lower quarter of the blades are going to be hidden. They would be using the radar blocker! Can anybody else see/know any other way of hiding the blades?

b_patel · Post by **b_patel** » 01 May 2010 04:33

Quite frankly, I don't see why they keep mention a SRAAM, the bay looks large enough to manage an R-77.

I don't know if its long enough to hold an R-77. I would assume they are trying to fit 2 R-73's in there. That way the PAK-FA would have a total of 10 internal missiles. But until we actually see an up close picture of it we will never know.

Looking at the plane from the side and the bottom, I don't feel that the inside lower quarter of the blades are going to be hidden. They would be using the radar blocker! Can anybody else see/know any other way of hiding the blades?

You cans see an S-duct or at least a partial S-duct from the bottom shot of the PAK-FA. Its all speculation but I would assume that they will either make an S-duct ala F-22 or have what is seen now and use a radar blocker. If they do use a radar blocker it would be the 3D coaxial labyrinth radar blocker, that is rumored to already be installed on one of the prototypes. There's a video of it on youtube i can't find it though.

shukla · Post by **shukla** » 01 May 2010 09:59

T-50 flies again

Thursday's test, from the Zhukovsky airfield in Moscow region, was piloted by experienced test pilot Sergei Bogdan. It marks the start of the main testing cycle, after preliminary flight tests were carried out in Komsomolsk-na-Amur in January, RIA Novosti reported.

shiv · Post by **shiv** » 01 May 2010 10:06

Just curious and this is with reference to the great advantages of stealth/internal weapons as well as TV maneuvering. It was stated that the MKI with its fancy maneuvers could snap up into an odd position and fire off a missile at a chasing aircraft. Butthat is fine for the MKI with weapons slung off its wings/fuselage. But how does an aircraft with internal weapons do that. Surely it will first have to open its internal bay doors and then maneuver, or maneuver and then open the doors and then fire the missile.

So is stealth and supercruise are developed for BVR fighting, then TV should be useless in the same fighter. NO?

Indranil · Post by **Indranil** » 01 May 2010 10:39

b_patel wrote:
indranilroy wrote: Looking at the plane from the side and the bottom, I don't feel that the inside lower quarter of the blades are going to be hidden. They would be using the radar blocker! Can anybody else see/know any other way of hiding the blades?
You cans see an S-duct or at least a partial S-duct from the bottom shot of the PAK-FA.

I observed that and hence said the inside lower quarters. 3D coaxial labyrinth radar blocker had been doing the rounds ever since the first flight, but I don't know how effective it is vis-a-vis the dual s-duct.

Indranil · Post by **Indranil** » 01 May 2010 11:06

shiv wrote:Just curious and this is with reference to the great advantages of stealth/internal weapons as well as TV maneuvering. It was stated that the MKI with its fancy maneuvers could snap up into an odd position and fire off a missile at a chasing aircraft. Butthat is fine for the MKI with weapons slung off its wings/fuselage. But how does an aircraft with internal weapons do that. Surely it will first have to open its internal bay doors and then maneuver, or maneuver and then open the doors and then fire the missile.

So is stealth and supercruise are developed for BVR fighting, then TV should be useless in the same fighter. NO?

A complete fighter excels in almost all arenas. What if a BVR fight ends with a no kill on both sides and one ends up in WVR! Or if we were outnumbered and you could take few of the planes out in WVR, but you are left with some planes do deal with in WVR. TV is a great thing to have in WVR! As you rightly noted, one can significantly decrease stall speeds in many maneuvers than with respect to a similar plane but without TV. This is very very handy when you are in front!

Weapon ejection through internal bays is a huge field of study and is very different from missile release from pylons. Its not just the ejection, other things like folded wings of the missiles have to be tackled. But care is taken to come out with ejections in almost all cases where a pylon release is possible. It consists large study of the ejection mechanism and the aerodynamic flow of air through the weapons bay once the doors are opened. I was discussing this with some friends here. Unfortunately, they wont divulge anything more. Their team works for a LM funded project and is bound by many legalities!

Viv S · Post by **Viv S** » 01 May 2010 17:15

shiv wrote:Just curious and this is with reference to the great advantages of stealth/internal weapons as well as TV maneuvering. It was stated that the MKI with its fancy maneuvers could snap up into an odd position and fire off a missile at a chasing aircraft. Butthat is fine for the MKI with weapons slung off its wings/fuselage. But how does an aircraft with internal weapons do that. Surely it will first have to open its internal bay doors and then maneuver, or maneuver and then open the doors and then fire the missile.

So is stealth and supercruise are developed for BVR fighting, then TV should be useless in the same fighter. NO?

I don't know about the PAK FA but a missile is ejected from the F-22's weapons bay in well under a second.

The AVEL employs a highly-reliable, non-pyrotechnic energy system controlled by aircraft electrical and hydraulic power. When commanded for in-flight missile launch, the AVEL system charges, and then safely ejects the missile through the air-flow boundary layer in less than 1/10 of a second. Safe ground loading operations are conducted with the AVEL in a ground-safe extended position.

http://es.is.itt.com/AMRAAMAVEL.htm

shiv · Post by **shiv** » 01 May 2010 18:14

The link says "through the air flow boundary" in less than 1/10 of a second. But the missile has to travel a short distance before getting to that boundary and an unknown (to me) distance after that.

In an era when aircraft are rotated 90 degrees or more in tenths of a second while maneuvering the ejection of a missile in "under a second" may well be a lifetime in close combat. Besides the door has to open too before the missile is ejected. Nothing is being said in public about this, Hence I ask.

A stealthy aircraft maneuvering with weapons bays closed might well be at a disadvantage in terms of release of weapons compared to a plane with ready to release weapons. The other thing is what is the radar signature when the doors open?

Viv S · Post by **Viv S** » 01 May 2010 18:37

shiv wrote:The link says "through the air flow boundary" in less than 1/10 of a second. But the missile has to travel a short distance before getting to that boundary and an unknown (to me) distance after that.

As I understand it the entire procedure till the missile clears the boundary layer takes place under a second. And since its ejection motion is transverse to the flight direction, it doesn't really need to go very far for ignition.

In an era when aircraft are rotated 90 degrees or more in tenths of a second while maneuvering the ejection of a missile in "under a second" may well be a lifetime in close combat. Besides the door has to open too before the missile is ejected. Nothing is being said in public about this, Hence I ask.

Relative to the missile's flight time, the time taken expended in ejection is negligible.

A stealthy aircraft maneuvering with weapons bays closed might well be at a disadvantage in terms of release of weapons compared to a plane with ready to release weapons. The other thing is what is the radar signature when the doors open?

Well, in close combat it doesn't really matter.

At BVR combat, it does compromise the aircraft's 'absolute' stealth but since the doors to the weapons bay are closed within seconds, its very unlikely that it would be detected let along tracked by a hostile radar.

Video of the F-22 firing a missile during a roll

Gaur · Post by **Gaur** » 01 May 2010 19:38

I had not seen the above video before. Thanks for that. This should end any discussions regarding any percieved delay in missile launch from weapon's bay.

Indranil · Post by **Indranil** » 02 May 2010 00:09

shiv wrote: In an era when aircraft are rotated 90 degrees or more in tenths of a second while maneuvering the ejection of a missile in "under a second" may well be a lifetime in close combat.

Nobody fires while one roles at maximum rate. Such maneuvers are used only shake off your tail. you would roll quickly to change your direction of turn or prepare for a dive, for scissors, your thach weave, split-S, Immelmann turn etc. But one doesnt fire while doing this maneuvers. Missiles are generally fired in a controlled turn or a dive in WVR. Please correct me if I am wrong.

shiv wrote: A stealthy aircraft maneuvering with weapons bays closed might well be at a disadvantage in terms of release of weapons compared to a plane with ready to release weapons. The other thing is what is the radar signature when the doors open?

Weapon-doors are opened just before the missile is fired and closed as soon as the missile has left the bay. During this short time in WVR the RCS is increased but not has much as a fighter with weapons on pylons! In WVR, RCS is no longer the most critical thing!

shukla · Post by **shukla** » 11 May 2010 20:26

STEALTH SUKHOI COMES BACK FROM SIBERIA

Sukhoi has moved its PAK FA/T-50 stealth fighter prototype from KnAAPO's Komsomolsk-on-Amur site in Siberia to Zhukovsky air base near Moscow for continued testing. The fifth-generation aircraft was transferred during the seventh sortie since making its flight debut in early February.

Austin · Post by **Austin** » 15 May 2010 10:08

Landing Gear up

Highres via Otaku PAK-FA

Pratik_S · Post by **Pratik_S** » 15 May 2010 18:39

Check out the latest images of PAK-FA
http://angle-of-attack.blogspot.com/201 ... ak-fa.html

Igorr · Post by **Igorr** » 19 May 2010 23:34

A new video with PAK FA was published in Internet

Indranil · Post by **Indranil** » 20 May 2010 01:22

Igorr wrote:A new video with PAK FA was published in Internet

I am so much not used to seeing movable LERXs

. They are awesome! I am like a little boy here, singing is is a LERX, is it a canard

.

Oh and by the way, I forgot to post about the elevators and wings being inline. I have to say that it is hearsay from people who are aircraft designers. Anyways this is what I learnt.

Owing to the lifting bodies of the modern fighter planes, the wings don't need to generate as much lift. For example, a F-22 is supposedly able to fly back with one severely damaged wing. Hence the wings of these planes are fairly thin. Somebody who had seen the F-22 said, it is no more than 4-5 inches. Even the Pak-FAs chamber looks fairly the same.

Hence the wake of such wings are fairly small. Also the role of elevators with TVR is greatly reduced except in the case of generating asymmetric lift. In that case, it is best to keep them along the longitudinal axis! This obviously leads to a lower RCS as well!

Hiten · Post by **Hiten** » 20 May 2010 06:51

two new videos of the PAK-FA

2010.02.12 T-50-1_4_25.mpg

20100129 T-50.mpg

shiv · Post by **shiv** » 20 May 2010 08:45

I am not the expert but have a general and approximate acquisition of knowledge from here and there and I have a query based on that.

I think the "lifting body" is related to low aspect-ratio wings which makes for easier wing-body blending and a thicker inner wing that can house fuel. But the concept of lifting body sparks off another question in my mind. Many missiles use lift provided by the body, but if you look at the video of the PAK-FA above - you can clearly see how it (like any other aircraft) loses lift and instantly loses altitude as its rolls 90 degrees.

I recall reading a description of some aircraft (Tornado??) which generated so much lift from its vertical tail surface (and from its body) that its loss of altitude was claimed to be low - and it could do what was described as a "razor sharp" fly by on its side with minimal loss of altitude. I have seen videos of aircraft doing a fly by in an attitude of 90 deg roll where the pilot deliberately rolls 90 degrees and actually points the nose slightly upwards (i.e away from the side of roll and towards the sky) so that the loss of altitude in with the plane on its side is somewhat compensated - albeit temporarily.

The question is whether a blended wing body design with short canted tailfins reduce body+tailfin lift in a 90 degree roll.

Pratik_S · Post by **Pratik_S** » 20 May 2010 17:39

I don't know if you guys observed it or no, take a look at the antenna like thing on the nose of the aircraft. If I am not wrong than its called a Kiel probe which provides things like air speed info to the computers. AFAIK such instruments are need for aircrafts which have very high angle of attack and for TVC. Its was the same thing seen of the X-31 and was also the reason for its crash. So If what I know/think is right than we can expect PAF-FA to be a super-maneuverable aircraft.

I am not entirely sure of what I just said so correct me if I am wrong.

NRao · Post by **NRao** » 20 May 2010 18:00

I think the "lifting body" is related to low aspect-ratio wings which makes for easier wing-body blending and a thicker inner wing that can house fuel. But the concept of lifting body sparks off another question in my mind.

The body itself is designed to generate lift. The most pronounced design was that of the YF-23. Both the Sukhois have this feature - perhaps not to the extent of the 23. I think it was deliberate in the 23 and now in the PAK-FA. In the 27 series pretty much everything was "accidental".

As you are aware the disks in AWACS are also designed to generate lift to compensate for their own weight.

two new videos of the PAK-FA

First one is the same as that posted by Igor.

The second is the very first vid that came out. Nothing new there.

Austin · Post by **Austin** » 21 May 2010 21:21

PAK-FA to get 5th generation ejection seat

Zvezda General Director and Designer Sergei Pozdnyakov told Interfax-AVN.

“The jet will have a fifth-generation ejection seat, which is better than ejection seats in existent warplanes by several parameters,” he said.

The ejection seat for the second fifth-generation plane has been supplied to Sukhoi, he added.

The ejection seat is being tested alongside the tests of the jet, Pozdnyakov said. The tests are taking place on land, because Russia has no flying laboratories. “The country used to have several aircraft with double cockpits, one of which tested ejection seats with dummies. For instance, we had Mikoyan MiG-31 and MiG-25 and Antonov An-12. There is not a single flying laboratory left, so the ejection seat is being tested at the Faustovo range in the Moscow region,” he said.

The flying laboratories were accompanied by another plane, which filmed the entire process of the ejection seat’s separation from the jet and landing. Now the tests are being filmed with video cameras placed along the test bench.

negi · Post by **negi** » 22 May 2010 01:18

shiv wrote: The question is whether a blended wing body design with short canted tailfins reduce body+tailfin lift in a 90 degree roll.

Boss imho a considerably high TWR and the fact that those tailfins are completely movable (unlike the smaller rudder on conventional designs) should address the issue.

Indranil · Post by **Indranil** » 22 May 2010 02:02

negi wrote:
shiv wrote: The question is whether a blended wing body design with short canted tailfins reduce body+tailfin lift in a 90 degree roll.
Boss imho a considerably high TWR and the fact that those tailfins are completely movable (unlike the smaller rudder on conventional designs) should address the issue.

I think Shiv has a very valid question. I don't think the plane can generate enough lift at 90 degrees. If you would use the fins for generating lift, wouldn't the torque produced, point the nose down?

How will the TWR generate lift?

Raman · Post by **Raman** » 22 May 2010 02:30

There seems to be a misconception on how an aircraft stays in the air in a knife edge. The fins are not producing the 'lift' to keep the aircraft up. Indeed, they cannot since they are well aft of the CoG and can only produce moments.

Instead the fins produce a yawing moment (with respect to the aircraft's frame of reference), which points the rear end of the aircraft down (with respect to the earth's frame of reference). This produces a vertical component of engine thrust that counteracts the gravitational force. Of course, this is a dynamic situation, so the rudders must be kept deflected to keep the aircraft "trimmed" for that attitude of flight.

BTW, this is no different than how any other aircraft flies a knife edge.

Indranil · Post by **Indranil** » 22 May 2010 02:57

yes, the aircraft will have its longitudinal axis stay horizontal (or whatever angle decided), but wouldn't the plane loose altitude unless the axis is an angle to the ground where the thrust's vertical component balances the weight of the craft (which has already been discussed by Shiv)?!

Shalav · Post by **Shalav** » 22 May 2010 03:00

In the 27 series pretty much everything was "accidental".

TsAGI would severely disagree with you there and point out both the MiG 29 and Su 27 series were based on their studies and specific design ideas on lifting bodies for Soviet 4g fighters. The design of the MiG 29 and the Su 27 were not accidentally lifting bodies.

Other lifting bodies include the Eurofighter and the F15.

----

indranilroy wrote:I think Shiv has a very valid question. I don't think the plane can generate enough lift at 90 degrees. If you would use the fins for generating lift, wouldn't the torque produced, point the nose down?

How will the TWR generate lift?

TWR does not generate lift. Hyperbole about what the Tornado's tailfin "could do wrt lift generation" does not mean tailplanes are actually designed to generate lift during turns.

Pratik_S · Post by **Pratik_S** » 22 May 2010 08:40

Can anyone help me on this:

I don't know if you guys observed it or no, take a look at the antenna like thing on the nose of the aircraft. If I am not wrong than its called a Kiel probe which provides things like air speed info to the computers. AFAIK such instruments are need for aircrafts which have very high angle of attack and for TVC. Its was the same thing seen of the X-31 and was also the reason for its crash. So If what I know/think is right than we can expect PAF-FA to be a super-maneuverable aircraft.

I am not entirely sure of what I just said so correct me if I am wrong.

NRao · Post by **NRao** » 22 May 2010 08:54

smpratik wrote:Can anyone help me on this:
I don't know if you guys observed it or no, take a look at the antenna like thing on the nose of the aircraft. If I am not wrong than its called a Kiel probe which provides things like air speed info to the computers. AFAIK such instruments are need for aircrafts which have very high angle of attack and for TVC. Its was the same thing seen of the X-31 and was also the reason for its crash. So If what I know/think is right than we can expect PAF-FA to be a super-maneuverable aircraft.

I am not entirely sure of what I just said so correct me if I am wrong.

pitot tube?

Pratik_S · Post by **Pratik_S** » 22 May 2010 09:08

NRao wrote:pitot tube?

Are you sure about it ? Take a look at X-31 video from 3mins 55sec and the PAK-FA video from 27 secs. They both look similar to me, i.e look like kiel probe.
X-31 Video:
http://www.youtube.com/watch?v=817w5ps7HwI
PAK-FA Video:
http://www.youtube.com/watch?v=qjpLejaErII

NRao · Post by **NRao** » 22 May 2010 09:16

No. I am not sure.

But, Kiel probe

A Kiel probe is a device for measuring pressure in fluid dynamics. It is a variation of a Pitot probe where the inlet is protected by a "shroud". Unlike the Pitot probe, it is not sensitive to changes in yaw angle, and is therefore useful when the probe's alignment with the flow direction is variable or imprecise.

Austin · Post by **Austin** » 22 May 2010 09:56

Better Quality Video of PAK-FA second flight link

What is mind boggling is the strong landing gear and the huge tyre looks to me they borrowed from a heavy duty truck

rahuls · Post by **rahuls** » 23 May 2010 10:01

I guess there was a lot of discussion about the S duct thing, and the compressor blades may or may not be visible. At 2.23 in this video clearly shows the compressor blades: http://www.youtube.com/watch?v=Mgb6NyxU ... re=related

Indranil · Post by **Indranil** » 23 May 2010 10:40

rahuls wrote:I guess there was a lot of discussion about the S duct thing, and the compressor blades may or may not be visible. At 2.23 in this video clearly shows the compressor blades: http://www.youtube.com/watch?v=Mgb6NyxU ... re=related

Please go back some pages and read ... this has been extensively discussed!

Pratik_S · Post by **Pratik_S** » 24 May 2010 16:33

NRao wrote:No. I am not sure.

But, Kiel probe

A Kiel probe is a device for measuring pressure in fluid dynamics. It is a variation of a Pitot probe where the inlet is protected by a "shroud". Unlike the Pitot probe, it is not sensitive to changes in yaw angle, and is therefore useful when the probe's alignment with the flow direction is variable or imprecise.

It surely is a Kiel probe. I think there are more applications of the Kiel probe than the ones quoted. AFAIK it should aid the pilot via computer in controlling the TVC nozzels. Something like that

.

NRao · Post by **NRao** » 24 May 2010 16:57

smpratik wrote: It surely is a Kiel probe. I think there are more applications of the Kiel probe than the ones quoted. AFAIK it should aid the pilot via computer in controlling the TVC nozzels. Something like that .

Kiel probe from X-31

And, at 27 sec pitot from http://www.youtube.com/watch?v=qjpLejaErII.

As far as I can read a Kiel probe has a "shroud" - which I cannot see in the PAK-FA!!! The PAK-FA also has vanes!!!

And, all such probes are used for speed, AoA, etc and I have never heard of them being used for controlling something. BTW, such "probes" do not exist in the final product. They are there during the testing phase and their purpose being served, typically removed in the final product.

Besides if you "think" there are more applications, then please google and find them for us.

Pratik_S · Post by **Pratik_S** » 24 May 2010 17:07

I will do my research and let you know.

Gaur · Post by **Gaur** » 25 May 2010 01:52

Very high res pictures of PAK-FA:
http://img7.imageshack.us/img7/453/pakfahirestop.jpg
http://img696.imageshack.us/img696/8749/pakfahires7.jpg
http://img163.imageshack.us/img163/2600/pakfahires1.jpg
http://img214.imageshack.us/img214/8320 ... ires14.jpg
http://img195.imageshack.us/img195/7217 ... ires10.jpg
http://img34.imageshack.us/img34/6697/pakfahires9.jpg
http://img94.imageshack.us/img94/863/pakfahires4.jpg

I know that 2 of them are reposts but they are in higher resolution.

NRao · Post by **NRao** » 25 May 2010 02:04

- self deleted -