China China to unveil J-35A stealth fighter jet

[Strong AI]

Flush air data sensors generally have more to do with hypersonic regimes (given induced drag forces, heating and so on):

https://ntrs.nasa.gov/api/citations/19990105883/downloads/19990105883.pdf

Pitot tube RCS is not significant design driver in say <Mach 2 regimes I believe (especially reading this paper and the calibration and sensoring trade-offs, especially in lower speed less-laminar flow regime)... compared to conventional probe past boundary layer.

Compared to signature of the canopy, flight control surfaces (in operation) and curved surfaces etc. These tradeoffs (for the aerodynamics) bake in lot more RCS return than the pitot tubes I would assume.

I don't know if this author is an expert but it looks like that air data sensors/tubes do affect RCS.

Obviously, the B-2 carries no external/protruting pitot tubes (that would affect the aircraft’s Radar Cross Section – RCS – making it less stealthy); to check airspeed, the aircraft uses static ports set flush into the skin.

This Close Up Photograph of the B-2 Spirit Provides A Fantastic View On The Stealth Bomber's Air Data Ports

This shot exposes a few interesting details about some of the B-2's sensors. The U.S. Air Force has just released some interesting photographs of one of

theaviationist.com

 

[Nilgiri]

I don't know if this author is an expert but it looks like that air data sensors/tubes do affect RCS.

Obviously, the B-2 carries no external/protruting pitot tubes (that would affect the aircraft’s Radar Cross Section – RCS – making it less stealthy); to check airspeed, the aircraft uses static ports set flush into the skin.

View attachment 76307

This Close Up Photograph of the B-2 Spirit Provides A Fantastic View On The Stealth Bomber's Air Data Ports

This shot exposes a few interesting details about some of the B-2's sensors. The U.S. Air Force has just released some interesting photographs of one of

theaviationist.com

Nice find. Yeah I guess the trade-off was worth it here, the B-2 does have a lot more capacity in avionics.

i.e The avionics cost being left more open ended (since only a squadron of B-2 planned or ended up being made I forget which) for B-2 compared to F-22 probably a factor here. To get that final few % increments in RCS improvement at greater cost etc, especially factoring in what is the size of the bird on hand at the nose area to host it too etc.

Per unit costs roughly:

B-2 : 2 billion USD
F-22: 350 million USD

(would have been somewhat lower if they produced a lot more of both, but the B-2 is especially capital cost loaded by low number etc)

From what I remember the F-22 avionics package started cutting down requirements early (to essentially focus on handling the radar primarily), so side mounted radars (what would eventually develop into DAS downroad for the F-35 etc along with EOTs) and even IRST were all given the chop. I'm unsure what's required onboard (that the B-2 clearly has with the price impact being less of a bar) for flush sensors here, though I would imagine its part of reason why it didnt make it to F-22 given what else was cut.

They are now looking to patch in IRST into the F-22 or example, a complicated effort:

F-22 Raptor To Get Distributed Infrared Search And Track System

Plans to add some form of increasingly critical infrared search and track system to the Raptors have been in the works for years now.

www.twz.com

The F-117 (the high stealth design driver approach with really low compromise to aerodynamics) had its own compromises again (no radar at all and constrained avionics capacity optimized to FLIR instead), so again the trade off for flush sensors, IRST etc deemed not worth it.

 

[Strong AI]

Nice find. Yeah I guess the trade-off was worth it here, the B-2 does have a lot more capacity in avionics.

i.e The avionics cost being left more open ended (since only a squadron of B-2 planned or ended up being made I forget which) for B-2 compared to F-22 probably a factor here. To get that final few % increments in RCS improvement at greater cost etc, especially factoring in what is the size of the bird on hand at the nose area to host it too etc.

Per unit costs roughly:

B-2 : 2 billion USD
F-22: 350 million USD

(would have been somewhat lower if they produced a lot more of both, but the B-2 is especially capital cost loaded by low number etc)

From what I remember the F-22 avionics package started cutting down requirements early (to essentially focus on handling the radar primarily), so side mounted radars (what would eventually develop into DAS downroad for the F-35 etc along with EOTs) and even IRST were all given the chop. I'm unsure what's required onboard (that the B-2 clearly has with the price impact being less of a bar) for flush sensors here, though I would imagine its part of reason why it didnt make it to F-22 given what else was cut.

They are now looking to patch in IRST into the F-22 or example, a complicated effort:

F-22 Raptor To Get Distributed Infrared Search And Track System

Plans to add some form of increasingly critical infrared search and track system to the Raptors have been in the works for years now.

www.twz.com

The F-117 (the high stealth design driver approach with really low compromise to aerodynamics) had its own compromises again (no radar at all and constrained avionics capacity optimized to FLIR instead), so again the trade off for flush sensors, IRST etc deemed not worth it.

View attachment 76308

Thanks for the answer.
This is my speculation now but afaik Jets like F-22 are optimized for front aspect RCS, whereas flying wings are optimized for all aspect RCS.
So maybe those sensors do have only a very low impact for frontal RCS.