Forum: General F-22A Raptor forum

If Stealth is primarily about shaping, what's to stop other countries from developing LO platforms by essentially copying the airframe shape from publicly available photos of the F-22/35

F-16.net Sponsor

The devil is in the details...

I watched a program once about stealth aircraft on t.v. In it they interviewed Dennis Overholser (who is a stealth community legend) He claimed, from my memory that it's all about "shape, shape, shape and then materials."

I'll try and find a transcript of the program to get the exact quote though it could be tricky as it was one of the very many programs on stealth that are floating about on the airwaves.

IamSpazzy wrote:

If Stealth is primarily about shaping, what's to stop other countries from developing LO platforms by essentially copying the airframe shape from publicly available photos of the F-22/35

Shape can certainly help lower the RCS, but....without knowledge of materials, and what's going on beneath the skin, you don't have the full story.

With regards to first gen stealth, like the F-117, it is all about shaping. The Russian paper that the LM engineer read and digested is all about how electromagnetic waves reflect back to the transmitter based upon geometry.

But its not as simple as just "copying" design. There's a little thing in engineering called GD&T, and with poor tolerancing in production, even a design that looks stealthy might be as big as a barn door on someones radar set.

Just because you can shape something similar to something else that is known to be LO, that does not make the copy LO. Take a piece of flat aluminum and start making measurements on its flatness and while it may look flat to your eyes, it can be full of deformations that cause it to behave differently to radar reflections than if it were truly "flat".

Airplanes are full of panels, rivets, moving things, and then alone, the stresses involved in flight can cause subtle variations than what it was when it rolled off the production line.

Stealth is part phyics, and just as importantly, it is part manufacturing abilities.

Then again, dirt, grease, and crud that get deposited on a stealthy airframe can also increase its reflectivity.

Anyone in the world can make a "stealth" airplane. But there's a difference between making something operational and stealthy, as opposed to it being some graduate students science experiement. Hell the Germans made a stealth airplane by accident in WWII.

So your original question was something about now that the world knows what stealth America's stealth airplanes look like, can't they just copy them? Our secret F-117 squadron wasn't secret because we were worried that if someone knew what it looked like, then they would copy it. No. It was secret to keep operational capabilities secret - not because the design was magical and if the bad guys knew what it looked like they'd copy it and have its magical capabilities.

That's impossible.
The RCS is very sensitive to even a variation of curvature. Other countries can't get the detail of the entire parameters by pictures.

Building the shape to the required tolerances could be quite difficult for countries which don't have the manufacturing expertise to do so. The distances between the gaps in the panels and control surfaces are important to consider as well.

Although Japan seems to have more-or-less copied the F-22 with their ATD-X. They claim an RCS "smaller than a bird, but larger than an insect" with a test model.

Remember what they said about the F-117. If even one of the rivets was protruding 1/16th in. up out of the skin the stealth was blown completely. Anyone not getting the shape or anything else associated with the stealth of the airframe 100% right doesn't get points for having it close, they get nothing.

"Stealth" is about a lot of things. Shaping just being a part of it with regard to defeating RF. Anyone who knows how to make Tx/Rx knows how to defeat it. The issue is more a matter of at what cost. That's what seperates theory from practice more often than not.

-DA

A former F-117 pilot told me that stealth is about 85% shape, 15% everything else.

Forum: General F-22A Raptor forum

Stealth and Shaping