Message posted by Magoo on November 16, 2000 at 05:01:45 EST:

I'm not sure the actual size of the model is an issue, at least not in the early stages of testing. The shape of the model and it's vulnerability or invulnerability to varying radar frequencies at varying angles is the main issue.

Computer modelling is used for much of the early RCS work, and the models are used more to verify the computers' figures rather than establish new figures. Of course, the final stages of testing are done with a production representative model, or even an actual prototype, as things like panel gaps, canopy glass, and even rivet heads can affect the final RCS figures.

One of the functions of these 'anechoic' chambers is not just to measure a direct return at the transmitter, but to also measure the radar reflection off the model from various other points within the chamber, and how much the original transmission is dissipated or absorbed by the shape.

One of the theoretical ways to defeat stealth is for multiple receivers to be used in conjunction with one or more powerful transmitters. The radar waves from the transmitter may not necessarily be reflected back towards it, and those radar waves that are not absorbed by RAM or clever shaping (e.g. the chines on the SR-71) have to go somewhere. The more receivers, the more likely a return will be seen by at least one of them. If two or more receivers that are spread apart can see a return, and these receivers are part of an IADS, then the position of the aircraft can be pin-pointed fairly quickly, and perhaps 'countered'.

Magoo

In Reply to: Re: X-32A JSF RCS trials posted by gary on November 16, 2000 at 03:09:54 EST:

Replies: