Can the F-35 match the PAK-FA

The F-35 compared with other modern jets.
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by XanderCrews » 24 Mar 2014, 02:14

loke wrote:
XanderCrews wrote:How will the stage 2 engine help its RCS? because they are going to find a better way to hide the obvious fan?

People with eyes who can see the engine fans. and doubt the claims that it can be fixed in anything other than band aid form.

Although I of course agree that the PAK FA will have a much higher RCS than F-22 and F-35, I wonder; what "obvious fan" are you referring to?

Can you really see the engine fans on the PAK FA?

I find that hard to believe; even the Gripen C (and probably also Gripen A?) had radars blockers. I find it very hard to believe that the PAK FA does not have either S fans or radar blockers.

Any sources to support you claim would be appreciated.


http://img703.imageshack.us/img703/1116/18062010a.jpg

http://i1094.photobucket.com/albums/i44 ... isible.jpg

download/file.php?id=14663&mode=view
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by spazsinbad » 24 Mar 2014, 02:26

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by sferrin » 24 Mar 2014, 03:26

loke wrote:
sferrin wrote:
loke wrote:I find that hard to believe; even the Gripen C (and probably also Gripen A?) had radars blockers. .


What makes you think any Gripen has radar blockers?

There was a video of the Gripen C inlets, clearly showing the radar blockers.

However it seems it has been pulled off youtube -- I was not able to locate it right now.

In any case; this was about the PAK FA not Gripen. What supports the notion that is has neither radar blockers nor s ducts?

Edit: although I did not find the video on Gripen I found this: http://forum.keypublishing.com/showthre ... ost1703927


Problem with that picture is there's nothing to indicate we're not just looking at the 1st fan stage.
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by spazsinbad » 24 Mar 2014, 04:02

Just for fun I'll hot link or upload the other two pics No.1 & then No. 3 in that order from above links:

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by rkap » 24 Mar 2014, 04:56

XanderCrews wrote:
I notice it is often assumed in recent times on this forum by many the RCS of both the F22 and F35 will be far superior to that of the Pak Fa. [A finished production Pak Fa.]


We havn't seen one yet, and there are problems that need to be fixed. so until we see fixes from the prototype the "production" versions which russia is promising very quickly, and doesn't point to big redesigns.

Since when has the F35 RCS become so good? Where does this assumption come from. Is there a reliable source for this? The USA is very secretive about the RCS of both the F22 and F35 giving in reality only hints.


asked an answered.

In other words you don't have an answer apart from the vague release made years ago that the F22 has an RCS of a marble and the F35 will have an RCS of a golf ball or whatever it was. If I remember correctly when that statement was made it said "If the RCS of the F22 is the size of a marble the F35 will have an RCS of about a golf ball."
The report by one well known Indian Reporter quoted by all "F35 fan boys" carries no real weight. That reporter has a reputation of doing articles along those lines. "A sh*t/stirrer" like many Indian reporters.
It is obvious we will simply have to wait to find out. I don't come to this forum often. Especially since all semblance of balance has disappeared in recent times. Where have all the more balanced contributors gone? After reading some recent posts I though I must have missed some key piece of information released by Lock-mart or the Designers of the F35 regarding the F35 RCS. Obviously not! Just a lot of biased speculation. I am not saying what you say "can't" be correct but I had hoped you had a credible source. Something like a statement made by a Head Designer.


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by popcorn » 24 Mar 2014, 05:22

rkap wrote:
asked an answered. I386

In other words you don't have an answer apart from the vague release made years ago that the F22 has an RCS of a marble and the F35 will have an RCS of a golf ball or whatever it was. If I remember correctly when that statement was made it said "If the RCS of the F22 is the size of a marble the F35 will have an RCS of about a golf ball."
The report by one well known Indian Reporter quoted by all "F35 fan boys" carries no real weight. That reporter has a reputation of doing articles along those lines. "A sh*t/stirrer" like many Indian reporters.
It is obvious we will simply have to wait to find out. I don't come to this forum often. Especially since all semblance of balance has disappeared in recent times. Where have all the more balanced contributors gone? After reading some recent posts I though I must have missed some key piece of information released by Lock-mart or the Designers of the F35 regarding the F35 RCS. Obviously not! Just a lot of biased speculation. I am not saying what you say "can't" be correct but I had hoped you had a credible source. Something like a statement made by a Head Designer.

If memory serves, the RCS approximations for the F-22 ( metal marble) and F-35 (golf ball) were provided by the USAF. That's as close you'll get as actual,figures are necessarily classified and likely even better. I guess it boils down to whom you believe has greater credibility and has demonstrated a track,record in actually building LO,aircraft
Last edited by popcorn on 24 Mar 2014, 06:31, edited 2 times in total.
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by spazsinbad » 24 Mar 2014, 05:45

The quote was from around Nov 2005 - I'll keep looking however this is one such quote:
"...According to November 2005 reports, the US Air Force states that the F-22 has the lowest RCS of any manned aircraft in the USAF inventory, with a frontal RCS of 0.0001~0.0002 m2, marble sized in frontal aspect. According to these reports, the F-35 is said to have an RCS equal to a metal golf ball, about 0.0015m2, which is about 5 to 10 times greater than the minimal frontal RCS of F/A-22. The F-35 has a lower RCS than the F-117 and is comparable to the B-2, which was half that of the older F-117. Other reports claim that the F-35 is said to have an smaller RCS headon than the F-22, but from all other angles the F-35 RCS is greater. By comparison, the RCS of the Mig-29 is about 5m2...."

SOURCE: http://www.globalsecurity.org/military/ ... design.htm

The PDF attached has same quote/source: http://faculty.nps.edu/jenn/EC4630/RCSredux.pdf (2.4Mb)

RCS Reduction (Chapter 7) EC4630 Radar and Laser Cross Section Fall 2011 Prof. D. Jenn
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RF STEALTH (OR LOW OBSERVABLE) AND COUNTERRF STEALTH TECHNOLOGIES: IMPLICATIONS OF COUNTER-RF STEALTH SOLUTIONS FOR TURKISH AIR FORCE by Serdar Cadirci March 2009

www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA496936 (2Mb) attached
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by Corsair1963 » 24 Mar 2014, 08:08

popcorn wrote:
rkap wrote:
asked an answered. I386

In other words you don't have an answer apart from the vague release made years ago that the F22 has an RCS of a marble and the F35 will have an RCS of a golf ball or whatever it was. If I remember correctly when that statement was made it said "If the RCS of the F22 is the size of a marble the F35 will have an RCS of about a golf ball."
The report by one well known Indian Reporter quoted by all "F35 fan boys" carries no real weight. That reporter has a reputation of doing articles along those lines. "A sh*t/stirrer" like many Indian reporters.
It is obvious we will simply have to wait to find out. I don't come to this forum often. Especially since all semblance of balance has disappeared in recent times. Where have all the more balanced contributors gone? After reading some recent posts I though I must have missed some key piece of information released by Lock-mart or the Designers of the F35 regarding the F35 RCS. Obviously not! Just a lot of biased speculation. I am not saying what you say "can't" be correct but I had hoped you had a credible source. Something like a statement made by a Head Designer.

If memory serves, the RCS approximations for the F-22 ( metal marble) and F-35 (golf ball) were provided by the USAF. That's as close you'll get as actual,figures are necessarily classified and likely even better. I guess it boils down to whom you believe has greater credibility and has demonstrated a track,record in actually building LO,aircraft



Well said.... 8)


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by disconnectedradical » 24 Mar 2014, 08:42

rkap wrote:I notice it is often assumed in recent times on this forum by many the RCS of both the F22 and F35 will be far superior to that of the Pak Fa. [A finished production Pak Fa.] Since when has the F35 RCS become so good? Where does this assumption come from. Is there a reliable source for this?
The USA is very secretive about the RCS of both the F22 and F35 giving in reality only hints.
The Russians from day one have stated they were designing the Pak Fa to have as good a RCS as the F22 in the long term. [With the Stage2 engine that should be available by 2018/2020]
Alexander Davidenko chief designer of the Pak Fa who will have had the best minds and data available determining the F22 RCS says in there mind the effective RCS of the F22 is between .3 and .4 sq. meters. [overall]. He also claims an RCS for the Pak Fa with Stage1 engines between .1sq.meter and 1sq.meter. The .1sq.meter is obviously the front on RCS and the 1sq.meter the sides etc. with the exposed Stage1 engines. Despite some still carrying on about the partly exposed compressor the Russians have said the intake ducts will be lined to scatter any reflections within the ducts. The solution put up by one of the more technical people on this forum years ago. From the front everything else being equal the Pak Fa has to have a good RCS. The Russians claim it will be better than the F22. Its entire front area is only a bit over 13sq.meters. The one remaining problem they have is there OLS. Again they have said recently it is designed to drop down flush when not in use. Odds are in the next 5 years this protusion will also be eliminated just like on the F35.


I think the USAF would be thrilled if the Russians believe that the F-22's overall RCS is 0.3-0.4 square meters. Also, I hope you're not buying into the whole "stealthy compressor face" crap for the Izd. 30 engines, are you?

My question is. Is there some reliable source to support this notion that the F35 in particular will have a far better RCS than the Pak Fa. Every scenario on here seems to assume that conveniently. This is at the core of the continuing assumptions the F35's will still be able to enter contested airspace protected with Pak Fa's backed up by say SU30's, late SAMS and good ground radar at will to me is wish-full thinking. If dealing with a near peer adversary I just can't see it.


And the F-35's will be operating without support?

Anybody who says its ceiling of 20,000m [already taken to about 73.000 feet in testing - over 22,000m] and ability to supercruise and good range will be of no advantage in that role has to be kidding themselves. Also if they have been able to keep to its original design weight of only 15,500kg empty it will certainly be able to climb with the wing design it has. A stealthy Mig25 with endurance, ground attack, anti-ship ability and extreme agility in many ways.


I'd really like to know how you obtained these figures.

Is all this talk about superior F35 RCS just speculation or wish-full thinking or has some real data been released by real experts. I mean something Official. Real Scientists and Engineers of most Nations don't lie. That is why I accept within reason what Russian Head Designers say. It is a pity to me that Head Designers in the West are restricted from talking most of the time.
Can anybody tell me where this assumption the Pak Fa's RCS will be so poor comes from?


They may not lie, but they may tell half-truths that are so out of context that the information is basically worthless. Applies to both Russian and US designers, and it's frankly double standard to treat Russian claims as gospel truths and summarily dismiss USAF or LM sources.


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by popcorn » 24 Mar 2014, 11:03

If the logic is that the country of manufacture would be in the best position to know the RCS of it's aircraft, who are intimately familiar with their proprietary LO design features e.g.,shaping, materials,,etc. then there's no roblem really.
Let's all agree that:

PAK-FA has RCS of .1 to 1 square meter (source =Sukhoi)
F-22's frontal RCS of 0.0001~0.0002 m2, marble sized in frontal aspect. (source = USAF)
F-35 is said to have an RCS equal to a metal golf ball, about 0.0015m2 (source = USAF)
Undoubtedly, these are the most credible figures available up to this time from sources that ought to know. Speculation on the other country's aircraft is best left to APA. :mrgreen:
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by munny » 24 Mar 2014, 11:07

rkap wrote:I am not saying what you say "can't" be correct but I had hoped you had a credible source. Something like a statement made by a Head Designer.


You will not get a straight answer for actual RCS or details on the approaches used for the publicly mentioned figures. But you can learn the theory and work out why the PAK FA is a heavily flawed stealth design...

A modestly qualified engineer explains the fundamental theory behind shape VLO from 20 - 60secs into this clip.

https://www.youtube.com/watch?v=2mADxVXMoN0

Effectively, angle of incidence is what its all about. The higher the angle, the smaller the return.

In the T-50 there's no magical, minor reconfiguration or upgrade that is going to change this picture. Properly shaped stealth aircraft are always going to have a massive LO advantage where the enemy has cooperative engagement capability (21st century adversaries)

Image

If they wanted to make a design with under-slung nacelles stealth from the beam aspect, they'd need to separate the engines much further or halve the size of the bays.

Image

Comparing equal sized surface for various stealth aircraft, you can see the difference between the angles flat surfaces of the 4 ) X-47B at 25 degrees, 3) f-22 at 55 degrees and 2) f-35 at 65 degrees compared to the cylindrical engine cowling of the 1) T-50 which is exposed at 85 degrees from the beam aspect.

Image

Image


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by zero-one » 24 Mar 2014, 11:25

smsgtmac wrote:I believe that Osley may also be mistaken about that turn spec at 30K feet though. A Blk15 F-16A at 25K ft, weighing just under 25K lbs carrying two AIM-9P3 missiles and a noseload of 20mm but otherwise 'clean' would 'only' pull about 4.5-.6 sustained Gs at .8M. I would be amazed if anyone expected the F-35 to do that much better at that altitude.


I understand that Sustained G is heavily dependent on multiple factors such as weight, speed, altitude,etc.
Adjust them and the sustained G will also change.

However, the thing that always bothered me is, for that particular weight, speed, altitude etc. the F-35s goal was to sustain 6Gs and at the very least 5.3Gs.

I'm not sure how close or how far off they were, Configuration 240-3 reportedly sustained 4.95Gs at 15,000ft at Mach 0.8,
http://www.military.com/features/0,15240,186349,00.html

So if the current configuration did 5Gs, they are not far off, but why did they have to reduce the requirement so far down.

The C model requirement was reduced from 5.1 to 5.0, if the A model acheived 5.0 as well, why not simply reduce it from 5.3 to 5.0 also just like the C?

this makes me think that the A model didn't make it past 4.95Gs,

Ofcourse all of this is for a particular set of conditions, but it doesn't change the fact that there was a time when 6Gs were conceiveable at that particular condition.

Not trying to rant, just saying that this is the lone asspect of the F-35 that I am not a fan of.


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by smsgtmac » 24 Mar 2014, 13:34

Zero-
First, if you're going to lift that quote, you should have also lifted the retraction...

smsgtmac wrote:
basher54321 wrote:
smsgtmac wrote:I believe that Osley may also be mistaken about that turn spec at 30K feet though.


The way it reads to me suggests he's only referring to acceleration with that figure.


Yeah, re-looking at the passage, I'm sure you're right. All the better. I was reading too much into his talking about both of the metrics at the start of the statement.
Air Vice Marshal Osley : The points that the Director of Operational Test and Evaluation made there about the manoeuvrability, as you point out it was the sustained turn and the transonic acceleration. He pointed out that the targets that have been set for those parameters were not going to be met by the F35. The figure of I think it was 55 seconds for transonic acceleration, the F35 was going to take 63.9 seconds to do that. That is obviously at a certain altitude, I think it was 30,000 feet, and a range of mach 0.8 up to mach 1.2.


As to
...but why did they have to reduce the requirement so far down.


'So far down'? This is what 'so far down' looks like:
Spec-Change-Bank-Angles.jpg
~1.6 degree bank angle difference
Spec-Change-Bank-Angles.jpg (36.18 KiB) Viewed 55570 times


As to why the difference is acceptable, see Vice Marshall Osley's comment about TOTAL capabilities.
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by zero-one » 24 Mar 2014, 14:46

smsgtmac wrote:'So far down'? This is what 'so far down' looks like:
Spec-Change-Bank-Angles.jpg



That is true, I've read your Blog multiple times and have tremendous respect for it and it's writer.

But as you also said in that article, the difference in bank angle will translate to a difference in turn rate.

Now depending on other factors such as speed and altitude, the difference may be a little or it may be a lot.

I'm puzzled by this, if 0.7Gs isn't much of a difference anyway, then why reduce the C models sustained turn rate requirement by 0.1G?

the difference in bank angle for 5Gs and 5.1Gs may be even smaller but significant enough for them to consider a revision.

Furthermore, the B model's 5Gs was reduced to 4.5Gs, why not 4.6Gs as well

I'm puzzled by all these 0.1G differences,

It makes me think that perhaps the test was done at a condition where 0.1Gs would make a significant difference in turn performance?

Does that make sense?


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by XanderCrews » 24 Mar 2014, 15:03

I don't come to this forum often. Especially since all semblance of balance has disappeared in recent times. Where have all the more balanced contributors gone?


Thats a great question. you might be the last of the group that still preaches an incredible stealthy Russian Foxbat that has all the virtues of the best russian aircraft and none of their vices.

Whats your opinion? Where do you think they all went?

and quoting APA doesn't make one "balanced" BTW

After reading some recent posts I though I must have missed some key piece of information released by Lock-mart or the Designers of the F35 regarding the F35 RCS. Obviously not!


Obviously so if you bothered to check the sources. :doh: blaming Indian reporters works too though.

Just a lot of biased speculation. I am not saying what you say "can't" be correct but I had hoped you had a credible source. Something like a statement made by a Head Designer.


Sukhoi and the USAF official statements aren't good enough? it was very kind of people to do the homework for you. Why that would have taken me at least 5 whole minutes of googling.

Like was already said rkap, i guess its who you want to give more credibility to, you have to reach a lot more and ignore a lot of stuff if you favor the pak-fa though. I am surprised that of all the things i wrote you singled that one out. :|
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