The fact is that shaping affects RCS returns. Radio waves reflect off objects when they strike them. If they did not you would not get any radar return. VLO shaping is all about controlling how the waves are reflected.

Granted, different frequencies are not affected by the same shape in the same manner, but the fact remains that a properly shaped VLO aircraft will have a greatly reduced RCS no matter what the radar frequency. This is not to say that the RCS will be the same, just not as bad as the “340km vs a F-117” suggests.

To support this assertion, I have a pic from a 2002 Cal-Poly VLO Bomber design study.

Things to notice:

1. They have no agenda to falsify data and they will fail the class if their data is not accurate.

2. All RCS measurements were done assuming bare metal.

3. RCS, across all bands, is affected by shaping. This affect is roughly the same (within an average of about 10db).

I should point out that the RCS software they used was based on the Physical Optics method, and therefore neglects edge diffraction, thus likely making their RCS analysis quite inaccurate- wildly inaccurate in fact for relatively electrically large objects (for example anything smaller than an aircraft carrier in the VHF). It seems to be otherwise a very interesting paper on combat aircraft design that I will read through though.

As for “failing their class if their data is inaccurate,” I think you vastly overestimate the stringency of undergraduate level AE design courses (coming from somebody who has been there). 😀 They are primarily intended as learning experiences and much less so actual design/research programs, and the students are undergraduates meaning they have little to no experience or higher education in some of the intricacies of aircraft design (such as nonlinear control theory or RCS shaping, which are graduate level). There is nothing wrong with this- it tests the students’ abilities to work in teams in a multidisciplinary project designing a comprehensive system.

You probably don’t want to use it as actual research source though- especially when talking about VHF band RCS (especially since they only tested down to 1 GHz, which is not VHF, and neglected edge diffraction, which is the dominant return source in the VHF for an aircraft sized target).

PS. Thanks for the link.