I’m not completely stupid when it comes to military and aviation technology, but here’s something I could never figure out…
Every description of stealth technology makes some reference to the radar signiture of a stealth equipped aircraft being “no larger than a bird” (or some similar comparison). But when the Iraqi radar operaters see a ‘bird’ fly across their screens doing nearly mach 1, wouldn’t they be a wee bit suspicious? Or is a bird sized radar signiature below the detection threshold of these radar systems making them effectively invisible? But someone’s got to be able to see these bird-sized radar signiatures or else they wouldn’t be describing them that way.
No site for this but I’ve always believed that radar signatures that small arent displayed to the radar operator. If they showed every bird on the radar screen it would end up as a mess so they filter them out.
the radar signature of stealth aircraft was smaller than a ball bearing (!), a point they explicitly demonstrated by gluing a ball bearing to the front of one craft to show how much it increased the signature. Rich describes the first demonstration, in which the stealth craft was literally undetected by the radar. I think they would have been appalled to have a radar signature as big as a bird.
Stealth technology can take many routes. Most common is to reflect back less radar signal than “normal”. This is accomplished by reflecting the signal in other directions and absorbing as much energy as possible with Radar Absorbing Material. The result is that the reflection sent back is smaller/less than what it should be. Radar identifies targets based on the radar signature. If the signature is small/diminished, it is difficult/impossible to determine what the target is.
Another issue is that it’s tougher to hit the target when it is so small. Radar guided missile systems follow the signature. Imagine the signature as a bright light bulb and a missile as being able to seek out light. If the light bulb is very dim and looks fuzzy, it’s a lot tougher for the missle to hit the target.
there are other means of stealth, but if I told you…
One of the bits of stealth technology that makes planes and ships look odd is eliminating curves, certain long straight edgeds and surfaces that meet at 90 degree angles. Look at the shape of a bicycle reflector sometime. The cube corner design is excellent at reflecting signals directly back to the source no matter what direction the signal comes from.
I seem to recall a story about some of the first tests of the Stealth Fighter’s radar signature involving a bird. They had the fighter parked some distance off and were pointing a radar at it and not seeing a thing till a bird landed on the plane at which point they could see the bird on the radar. (Or maybe they were mad at first at what seemed like a failure since they could see the plane on their radar till the bird on the plane [which they didn’t know was there] took off at which point the plane ‘disappeared’…I forget which way the story went).
Anyway, stealth planes are not 100% invisible to radar. What the planes do manage to do is seriously decrease the range at which a radar can detect them.
Put a row of dots on a paper (your radar sites) and draw overlapping circles with the dots at the center of the circle. You now have a continuous barrier of radar coverage through which no plane can pass without being noticed. Now decrease the diameter of these circles to (say) 20% of their original size. You will now probably have gaping holes in your radar coverage through which you can fly undetected.
I believe stealth fighters (and bombers) have an indicator in the cockpit that registers radar energy striking the aircraft. If the energy rises above a certain level the pilots know it is possible a ground radar has spotted them. Long before that happens however the pilots adjust course and weave their way between radars and hence they are never seen.
As for radars filtering out birds that isn’t really an issue. It may be true but it is also possible to tell those filters to not filter out birds travelling near Mach 1 (or whatever speed you choose…probably more like 100 MPH).
Also remember stealth technology goes beyond radar. The Stealth Fighter is also protected from thermal imaging by cooling and redirecting exhaust up from the aircraft.
The final bit of stealth technology is fooling the eye (camoflage) which the Stealth Fighter does NOT do. The original plane called for an ugly blue color which, tests had shown, was actually more invisible at night than black was. For some reason the Air Force decided that image was more important in this case and painted the planes black. I will grant that the planes definitely look cooler black than they did in that ugly light blue.
I’ve read that one of the largest radar returns you get from the stealth is from the pilot’s helmet.
Anyway, the stealth does not completely absorb the radar signal coming in, instead that funny shape of the body is specifically designed to point the reflected radar along specific lines, so that most of the time you almost get no energy at all reflected back towards the radar set. The angles are designed such that at most angles ground based radar won’t be able to pick up the plane. However, an airborne enemy with radar is going to see one of two things, either almost nothing (similar to the ground), or it’s going to happen along one of those reflection lines, in which case it’s going to get a huge return. Minor variations in the orientation of the plane are going to give either a very large or a very small return, making it almost impossible for radar devices to get a good lock on the plane.
Reducing the optical and thermal signatures are not really that important. They’re only of value in reducing detection from other aircraft, but given the range at which infrared search/track systems and the Mk1 Eyeball are effective, then the issue is pretty much decided. If an enemy interceptor gets that close, you’re most likely going to be detected regardless…which, of course, means you’re screwed, in your slow, unmaneuverable, unarmed aircraft.
We can start by clarifing the definition of radar signiture. This only has to do with the AMOUNT of radar energy returned. Different objects have no “shape” to conventional radar. They either reflect enough energy to detect or they don’t. Saying something has a radar signiture of a bird simply means that on average you would expect it to reflect as much radar energy as a bird. This can be reduced by controlling reflection angles (making the energy bound back some direction besides to the source antenna) or by absorbing it. A rather direct analogy would be this: You are shining a flash light around your dark back yard. If there is a mirror back there that would reflect your flash light back to you, it would be easy to spot… one that reflects the light up into the sky would be nearly invisible. Also, someone dressed in white would be much easier to see than someone dressed in black.
ANY object that reflects enough energy to detect is a target. Non moving targets are filtered out due to their lack of phase shift between successive radar pulses. No effort is made to filter out birds. Birds generally do not show up because meat is a poor radar reflector and they are not large anyway. Occasionally large groups of birds do show up. Also birds generally don’t fly high enough to be above the “radar horizon” (in the line of site of) except when they are very close to the radar, often closer than the minimum range the radar can process targets at.
And the U.S., at least, has radars quite capable of tracking stealth planes when they are not coming straight on to the radar. Of course, the aircraft is optimized for frontal radar contact.
And a typical way to use the stealth plane is approach the closest radar head on and then bomb the crap out of it. It won’t see you at a side angle if it is blown up. Then the rest of the planes can follow.
This is completely inaccurate. The windows over the cockpit of a stealth plane are completely opaque to radar. The is required, otherwise the interior of the cockpit would make a great radar reflector. That glass has a thin metalic coating (similar to window tinting) that makes it conductive. This makes it look like a mirror to radar waves.
