I know that radar cross section (RCS) tests were performed on geometric models of both the YF-22 and the YF-23 prototypes submitted for the Advanced Tactical Fighter (ATF) competition, but were the same tests performed on the actual YF-22 and YF-23 prototypes when they were in flight?

Both designs had the correct shaping to their outer machine lines in order to minimize radar cross-section, but there is a noticeable difference between those prototypes and, say, the production F-22 in terms of very small details i.e. RAM inlays, putties, tapes around doors, etc. A similar phenomenon was observed with the X-35 JSF when compared with the F-35 Lightning II development aircraft. That makes me wonder if such an RCS test was part of the ATF competition.

  • $\begingroup$ I wonder how useful that would be, since the measurement would be further off from the final product than simulation and ground testing. $\endgroup$ Oct 26, 2017 at 19:30
  • $\begingroup$ Probably not, I would guess. A numerical model would probably more closely predict the F-22's RCS than the pre-production, pre-EMD YF-22/23. I'm fairly certain they tested scaled models on the pole before the YF-22 even flew in 1991(?). And they did later (1999) verify the F-22's RCS with a 'full-scale replica built to production tolerances'. If YF-22 pole testing did happen, Ben Rich might've mentioned it in Skunk Works, but I don't recall. $\endgroup$ Oct 26, 2017 at 22:35
  • $\begingroup$ Also, here's the YF-23 DEM/VAL presentation by Paul Metz and Jim Sandberg. It's been too long since I've watched it to recall whether they touched on pole testing. $\endgroup$ Oct 26, 2017 at 22:36

1 Answer 1


Low radar cross section (RCS) was a principal 1986 requirement for the Advanced Tactical Fighter (ATF) selection program that selected the YF-22 and YF-23 prototypes for a fly-off competition.

I am certain that both prototypes, or at least accurate models, were pole-tested during the evaluation period. Remember, this was in 1986, when computer modeling of RCS was in its very early stages of development. This testing was probably done at either the Area 51 RCS test range, or Lockheed's Helendale RCS test range.

For more first hand information about the YF-23, see this YouTube video.


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