What makes for stealth!

[ghoti]

What factors come to play in minimizing radar signature of a model plane? First, I think, would be to replace metal, where possible, with a non conductor. Example might be, for starters using a slow stick, replace the aluminum fuselage with the newer glass fuselage. Then replace push rods with glass composite rods/tube (stiff enough?) or with plastic rod inside of plastic sheath type control rods. Or go to pull-pull for actuating control surfaces using fishing line or something. Then maximize length of these to minimize copper wire length from servo to Rx, etc, etc. This leaves motor, ESC, Rx, LiPO, and servos as radar reflectors. How effective is this effort? Can these parts be shielded some way?

The camera is of metal body. Are there any made of plastic? I am just curious about how these thing work. Any experts out there?

[dfalcon]

The first thing that comes to mind is: Why in the first place does your rc plane need to evade radar?

[Mel Duval]

Radar signature is a function of material and shaping. The distance a given radar signature can be seen is a function of the radar which is being used for detection and tracking. With only the battery, radio and the battery, the radar signature would be minimal. With a 2.4GHz radio (short antenna!) and if you limit the spread of the servos, that is about the best you can do. If you wanted to get better than that, it would take adding some Radar Absorbent Material (RAM) and doing shaping on a composite airframe. RAM is heavy, typically frequency selective and VERY expensive. The airframe would be very expensive also.

The bottom line is as dfalcon says, WHY?

[ghoti]

I just got a new SS kit with their new glass fuselage and got to wondering about the difference in weight, strength snd what else? I haven't flown it yet.

. . . like I said, I'm just curious; I have no need nor desire for this. Thanks for the thoughts.

. Bill

[JetPlaneFlyer]

Geometry is a big factor. You will notice that stealth aircraft have no vertical surfaces to reflect (horizontally travelling) radar waves. Eliminating vertical surfaces is the reason stealth aircraft have either no vertical fins or twin fins canted over at an angle, also the reason they usually have sharp edged fuselage shape rather than cylindrical, it's all about minimising vertical surfaces that will reflect radar back to its source.

Stealth aircraft are however only 'stealthy' from the side. If they bank over or if the radar hits them from below then they will present a radar signal pretty much like any other aircraft.

Steve

[MarkusN]

As JPF says: Geometry is key. Things to be avoided are metal corners meeting at 90°, as they are sure to reflect waves back into the direction they have come from. Same with cylindrical surfaces, as one part of these is bound to stand perpendicular to the incoming waves.

About signature of RC and battery being minimal: Not so sure about that. I have read an anecdote about testing of early stealth aircraft. At one time a bird was sitting on the mock up being tested (set up on a big wooden scaffold). The bird doubled the radar signature of the plane...

[AUAeroEng]

Model airplanes are typically so small that a radar wouldn't pick it up as anything significant anyways.

[soar-ne]

A long time ago in a country far far away on sunday mornings (no air traffic) we flew RC at one end of the runway at a Air Force base, both power planes and sailplanes off hi-starts. I was a Ground Control Approach radar tech. The GCA radar would not show any target at all. Of course at that time all the models were wood. But that was then and maybe systems are better now...........
My .02s
Bob

[ghoti]

A long time ago in a country far far away on sunday mornings (no air traffic) we flew RC at one end of the runway at a Air Force base, both power planes and sailplanes off hi-starts. I was a Ground Control Approach radar tech. The GCA radar would not show any target at all. Of course at that time all the models were wood. But that was then and maybe systems are better now...........
My .02s
Bob

Thet had antennas so not much difference from a contemporary foam magpie, no?

[ghoti]

Model airplanes are typically so small that a radar wouldn't pick it up as anything significant anyways.

Maybe so, maybe not. CHAD dropped in WWII and later to confuse RADAR was smller than my slowstick I would guess?

[HELModels]

heah, Ghoti, what do I know but maybe Chaff effect on radar is a multipath, formation effect on radar - lots of it. Plus, the chaff probably had lots of wrinkles to act like corner reflectors. Just a guess.

[MarkusN]

Chaff is adapted to the wavelength of the radard it's supposed to blind. The metal strips are optimal resonators.

And there's lots and lots of them.

[soar-ne]

The chaff use that I have seen on older (40plus years) search radar overloads the receiver portion on the set with a huge target of thousands of reflecting objects over a large area which effectivly blinds the radar. I remember seeing just a strobe on the CRT but the aircraft blip was hidden in the strobe so you couldnt tell where it was or the range from the radar set. I know they have counter measures to it now but havent kept up with the technoligy so dont know how it works. Probably frequency shifting of some sort my guess.

Bob