How does stealth work? Why can’t we just tune radars to look for very fast ‘bumblebees’?

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I was watching a youtube video about the b2 this morning. It mentions that while it’s not completely invisible to radar, it only has a cross section about the size of a bee. It says that radars have to fine tune their displays to only show larger objects or else it would be too cluttered.

I guess my question is, why can’t they tune their displays to only show objects moving faster than ~ 300 mph?

In: Physics

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Anonymous 0 Comments

The spectrum of your radar has a certain energy before you turn the beam on, this is called the noise floor. You can’t make that go away, it’s caused by the Sun and all the electronic technology in use.

To see the stealth airplane you need a return from the airplane that you can detect, it has to be about twice the noise floor. Modern stealth shapes reflect away so much energy (that’s why they have those fun-house mirror shapes) that you have to pump a dangerous amount energy out to get a return 2X the noise floor. Alas, when there is more than one radar, your super powerful radar raises the noise floor in all the air you shine your beam into. It’s a diminishing returns problem. Eventually you’ve got a beam that drops birds out of the sky wherever it points, and stealthy planes are still stealthy.

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