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Subject: 2009 displays of the F-22 and the Rafale
Bluewings12    6/24/2009 5:03:48 PM
Let 's watch them first :-) The F-22 h*tp://www.air-attack.com/videos/single/cAhL7lJCk4I The Rafale : h*tp://www.dailymotion.com/user/ministeredeladefense/video/x9ma8h_demonstration-du-rafale_news Both aircrafts are pulling nice stuff . Rafale only does it twice faster . Explaination and details to follow . Cheers .
 
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Herald12345    Incompetence   8/5/2009 2:48:07 AM

It goes directly to wrong choices which has been a continuous theme I have about most technological incompetence..
 

Until the end of the Cold War, French have tended to use their own standards which are close to NATO but not exactly the same. See the 68mm rockets, the weird twist of the 5.56 FAMAS rifle... This allowed them to make loads of money because their customers could not easily integrate NATO weapons and had to buy French ones.

 

That's not technical incompetence, it's commercial ingenuity at its best.

 

Of course, after the end of the Cold War, everyone started to buy US stuff and that strategy has backfired quite a bit (even at home, they can't find a commercial ammo supply that works ok in their assault rifle...).

 

 

In the case of the Rafale, radar is angled as well

It is the whole front part of the radar which is angled

You can see the reard attachment and angles , plus inclination of surface on the top

However angle is lower than in former US AESA display which means that optimisation is different.

After all Rafale is optimised for low altitude penetration.
 

Correst. ESA radar angle is a trade off between ground and air mode (e.g. the B-1 array is angled downard).

So that a SAM radar can look directly at it in passive mode and hunt for sidelobe noise.

Chuckles de Gaule, Laugh it ups, and the Squall. Three major projects, three failures..
And what do they all have in common? WRONG SOLUTIONS and incompetent execution at the system level.
 
Not even economic sense did they make after you run the numbers. Italy gets more bang for the Euro.
 
Herald

 
 
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gf0012-aust       8/5/2009 3:07:17 AM




fs > As a gift for our US readers

Some interesting confirmation in a public NATO document of what I have explained before:

etc......

gf > as you would know, that is an extremely dumbed down articulation of RCS management opportunity and principles.....  there are no longer 4 basic principles for RCS management. - and in real terms that hasn't been so for nearly a generation.  I can only suggest that the above is intended for a very very basic delivery of first order principles 

just noticed the dates on that doc, so I guess my comments are self evident....
 
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Phaid       8/5/2009 4:49:41 AM

The APG-77s array is angled? That's news to me! Thought the APG-79 was the first one with an angled array, followed by the -81.

Yes, it is angled.  Even without a shot of the array itself, it is obvious from the way the radome meets the fuselage:
 
http://www.defenseindustrydaily.com/images/AIR_F-22_Side_and_F-15_Underside_lg.jpg" />
 
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Phaid       8/5/2009 4:53:22 AM
How about "as a gift for our US readers" everyone just stop replying to that idiot?
 
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MK       8/5/2009 7:28:08 AM



The APG-77s array is angled? That's news to me! Thought the APG-79 was the first one with an angled array, followed by the -81.



Yes, it is angled.  Even without a shot of the array itself, it is obvious from the way the radome meets the fuselage:

 

http://www.defenseindustrydaily.com/images/AIR_F-22_Side_and_F-15_Underside_lg.jpg" />
Thanks. Just remembered the image Herald showed as well and the antenna didn't look angled on that image. The first image showing an AESA onboard the test bed aircraft didn't look like the F-22s array, the second one does if you just take into account the F-22s nose shape. But it might be an image perspective related issue.
 
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Herald12345    That was a test stand.   8/5/2009 8:12:57 AM







The APG-77s array is angled? That's news to me! Thought the APG-79 was the first one with an angled array, followed by the -81.







Yes, it is angled.  Even without a shot of the array itself, it is obvious from the way the radome meets the fuselage:



 



http://www.defenseindustrydaily.com/images/AIR_F-22_Side_and_F-15_Underside_lg.jpg" />


Thanks. Just remembered the image Herald showed as well and the antenna didn't look angled on that image. The first image showing an AESA onboard the test bed aircraft didn't look like the F-22s array, the second one does if you just take into account the F-22s nose shape. But it might be an image perspective related issue.

inside a test chamber.
 
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french stratege       8/5/2009 9:59:58 AM

s > As a gift for our US readers


Some interesting confirmation in a public NATO document of what I have explained before:

etc......



gf > as you would know, that is an extremely dumbed down articulation of RCS management opportunity and principles.....  there are no longer 4 basic principles for RCS management. - and in real terms that hasn't been so for nearly a generation.  I can only suggest that the above is intended for a very very basic delivery of first order principles 
 
And I agree with you.It is old document on basic principles.However it has become a public document published on NATO site and probably the first one where active cancellation is mentioned.
Nothing new for specialists of informed engineers but it bring an official confirmation to some SP amateurs who doubt it and though it was only a rumor.
If you check routinely internet you would notice that much more information is now publicly available on stealth and for a simple reason.
Chineses or Iranians (and others) have published openly some scientific documents on stealth management from various research institutes which show that hiding some old information is not any longer relevant.They know how to calculate and simulate numerically an RCS and have shown they can do basic things on signature management.Which does not means of course that they are at the same level of USA or France or UK.
An interesting document on Lampiridae stealth management
ftp://ftp.rta.nato.int/public//PubFullText/RTO/MP/RTO-MP-006///$MP-006-21.pdf">ht*p://ftp.rta.nato.int/public//PubFullText/RTO/MP/RTO-MP-006///$MP-006-21.pdf
 
PS: for Herald
If there is a nation which manage very well system level management outside USA, it is France.
Our M51 work, our Triomphant class work ,and Rafale has well.In initial budget minus few percent more or less, in time,  and with predicted performance.Russians could learn something! LOL.
To think that we would not have thought about radar antenna proper angle effect on Rafale RCS is absolutely of the highest stupidity from you .Especially from french engineers who know very well math and physic when they come from first rate school like Polytechnique or Centrale.
We maybe have smaller R&D budget than USA but we are not stupid and ignorant.
 
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FJV    Still a wierd topic though.   8/5/2009 3:48:05 PM
Strange how such obvious things are not an issue among an "indepth" stealth discussion until they get mentioned.
 
- If the Rafale doesn't fly that high then angling the radar up is indeed not as beneficial as it would be for the F22.
- As for active radar cancellation. I suspect that for some frequencies the electronics may not be fast enough to do
  that.
- And if you slice a cilinder at an angle you get a elliptical form, which is what Herald was hinting at,
 
What also suprises me that I've seen no-one considering whether having 2 engines on top of each other might have stealth benefits:
A unique way of minimising the drag of the twin engine installation was put forward by Petter. This involved stacking the engines vertically (staggered to avoid too much weight aft, with the lower engine forward of the upper), effectively tucking them behind the cockpit, fed from the nose and achieving minimum frontal area. This effectively gave twice the thrust of its contemporaries for an increase in frontal area of only 50%.
 
Using such an approach might make a stealth fighter with a smaller frontal area compared to a stealth fighter with the engines side by side. (given equal front area neede for inboard storage of weapons).
It's also good for supercruise.
Maybe it's even possible to reduce (near) vertical tail surfaces, if you use thrust vectoring for the lower engine, due to the an arm for a momentum to work on. (you vector the lower jet nozzle from left to right instead of up and down)

This is still the non-expert talking here.
 
 
 
 
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VelocityVector    FJV   8/5/2009 4:18:07 PM

With over and under you complicate ductwork, tail and side aspect stealth, and internal space arrangements.  If you reduce beam somehow, doesn't that likely reduce the volume of your main bays?  I am a Lightning fan, too.  0.02

v^2
 
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gf0012-aust       8/5/2009 5:24:52 PM


And I agree with you.It is old document on basic principles.However it has become a public document published on NATO site and probably the first one where active cancellation is mentioned.

not so sure I'd drill it down so finely to the issue of people not accepting active cancellation.  the issue has been the degree and capability of an active cancellation capability (and I'll use Rafale as the trigger for this as its the one that has been oft used as the example on both sides)

it requires sufficient on board power
it requires a basicly clean emissions sanitised  platform otherwise it creates a nightmare for numbr crunching (signature emission is all aspect. so the dirtier the platform the harder it will be to manage its emissions).  there is no such thing as a "front on RCS" as flight, no matter how unruffled the air space, no matter how clean the flight management systems etc... are, will always involve a shift away from perfect linear transit when going from A to B.

again, aerodynamics and fluid dynamics are kissing cousins, active cancellation issues are similar for both, granted there are differences in propogation, absolute distance, absolute speed of signature "transmission" etc...  but tyhe core principles are similar.

unless you're flying a perfectly conformed sphere (and not many  spheres are not perfectly formed) - you will get signal variances.  anything that is not symetrical (and that means dirtied up with weapons, refueling probes, external sensors, pitots, irregular control surface housings etc....  will be harder for any active process to manage and manipulate the degree of its presence.

you just can't "bolt on" active cancellation.  the platform has to have inherent signature sympathy in the first place.  dirty airframes are not sympathetic.  when they're not they then become a flying transducer.
it requires evidence of all aspect sensor distribution
 
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