A pal says the Stealth Bomber is invisible to bats. Is it true or is he umm... batty?

[Fubaya]

@WarmNPrickly

I don’t think the paint will have any effect on the bats sonar. The only reason that could be any plausibility to this, is because they are both waveforms. They might reflect similarly. Sonar will not induce anything in magnetic materials.

I didn’t mean it that way. I was thinking more along the lines of bats seeing the metallic balls in the paint and thinking they’re a swarm of insects or something. Maybe a stealth is actually more visible to bats, they just think it’s something else. Pure speculation, of course, I’m just thinking that, if it actually happens, maybe it’s because something about the plane is screwing with their heads instead of it simply being too stealthy to detect.

[WarmNPrickly]

@astro

Stop all this insanity! The planes are NOT invisible to bats as a function of their stealth technology. The polygons, the paint etc are designed to deter detection by RF microwave frequencies not small mammals using ultrasound. Stealth composites and paints are not sound absorbing in the least.

The only possible scenario of bats not “seeing” them is if they are painted dark/black in a dark hanger and the bats literally run into them because they can’t see them visually. As bats can use echolocation to get around fine in near pitch black caves this scenario seems highly implausible.

I was under the impression that the most important part of stealth technology was not RF absorbing paint, but the shape of the wing that reflects the radiowaves away. In which case, there are many cases where two completely different types of waveforms react similarly to a physical object. You can do the double slit experiment with sound as well as with light. Given that the wavelengths of the two waves are similar, I don’t see any reason that this can’t be true, as long as the material reflects sound the same way.

On the other hand, it sounds an awful lot like an urban legend, so I can go either way.

[Don_t_Call_Me_Shirley]

Bats don’t use their sonar all the time. Studies have been done that show that bats are capable of keeping very good maps in their heads. When they are flying through their caves they often use no sonar at all. If you put an obstacle in a cave a lot of bats are likely to fly right into it because their sonar was off and they were depending on their internal map.

Maybe they parked the planes in a different place than what the bats were used to, and they were flying on “autopilot,” so to speak.

Also, isn’t there a fundamental difference between sound waves and electromagnetic waves? I thought radio waves only traveled in straight lines, which is why the funky angles on the 117 worked. But sound waves spread out in all directions, which ISTM should at least lessen the effectiveness of the stealth features when hit by sound waves.

[Fubaya]

For what it’s worth, I found this (google cache, original times out).

Interesting incidents were observed by F-117A maintenance crews during the Gulf War. Here is a short description from At the Controls: F-117A Stealth Fighter, by Jon Lake: “The effectiveness of F-117A’s RAM skin was demonstrated in an unusual manner during the Gulf War, when groundcrews started finding dead bats around the tails of hangared aircraft. The unfortunate creatures had clearly flown “full tilt” into the Black Jet’s tailfins, which their high frequency ‘sonar’ had been unable to detect.”

The story of “dead bats” in fact has nothing to do with the F-117A’s “stealthy” properties. Bats use ultrasonic signals for echolocation: these are mechanical compression waves not electromagnetic waves, as in case with radars, and have certainly nothing to do with the radar absorbent paint or any geometrical properties of the F-117A. The ultrasonic signals emitted by bats are narrow and highly directional and will reflect from most surfaces, RAM or no RAM. To explain the “dead bats” phenomenon we only need to remember that the F-117As use highly toxic paint and that the aircraft were stored in hot hangars with restricted ventilation. If the maintenance crews have spent as much time in these hangars as bats did, the bodies of bats would not have been the only dead bodies found around F-117As.

[Fubaya]

Also found a whole compilation of bat/stealth lore here with a couple different explanations that sound pretty likely.

[billfish678]

@Don_t_Call_Me_Shirley

Bats don’t use their sonar all the time. Studies have been done that show that bats are capable of keeping very good maps in their heads. When they are flying through their caves they often use no sonar at all. If you put an obstacle in a cave a lot of bats are likely to fly right into it because their sonar was off and they were depending on their internal map.

Maybe they parked the planes in a different place than what the bats were used to, and they were flying on “autopilot,” so to speak.

Also, isn’t there a fundamental difference between sound waves and electromagnetic waves? I thought radio waves only traveled in straight lines, which is why the funky angles on the 117 worked. But sound waves spread out in all directions, which ISTM should at least lessen the effectiveness of the stealth features when hit by sound waves.

As for the first part, I can attest to that firsthand. Bats do appear to be going by memory sometimes in a cave. I’ve been hit by them numerous times.

Waves are waves, yes and no.

Lets say you have a flat surface. You place it at an angle. You send out pulse. Those waves will propogate outwards, spreading out as they go.

The flat part WILL reflect most of that signal in a direction that is NOT back towards the source. The EDGES will diffract those waves in ALL directions, some of which is back towards the source.

How much energy gets reflected back towards the source from the flat part depends on how smooth and flat the flat part is. How much gets diffracted back from the edges depends on the ratio of the size of the waves to the geometric size and shape of the edges.

If the wavelength of the sound wave is about the same size as the radar waves, then you are going to get a similiar return or non return as it were, many other things being “equal”.

Imagine the F117 with really nice mirrors on the flat surfaces. In a night sky, shining a beam of light at it, you’d have a damn hard time IMO seeing it. And visible light is significantly different from radar waves in size, and both are different from sound waves.

The coatings and material properties that might react highly differently in how they reflect sound vs radar could make a difference.

But, the general idea of the F117 to use all those flat panels to reflect radar some other direction than where it came from should work in principle on sound waves as well.

I am not saying bats can’t see the 117 very well, but it certainly would not surprise me greatly if they couldnt.

[WF_Tomba]

@Fubaya

Also found a whole compilation of bat/stealth lore here with a couple different explanations that sound pretty likely.

So, to add to our growing pile of ideas: sightings of dead bats in an airbase in Saudi Arabia could simply have been the result of exterminators taking out a bat colony, or bats could have been killed by high-frequency noise and/or blast from the jets’ engines.

Plus, one pilot supposedly says he passed through the aircraft shelters at the airbase in Saudi Arabia several times a day for six months and never saw a single bat.

This whole thing really smells like an urban legend to me.

[billfish678]

If you really want to read something interesting. Read about the bat bomb project in WW2.

It was damn clever idea that could have done more damage to Japan than the atomic bombs did.