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Eliminating contrails from flying could be cheap

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101–110 of 206 posts

Re: Eliminating contrails from flying could be cheap

#101
N2O (laughing gas) is not combustible, but autodecomposes into a mixture composed of 1 part oxygen gas and 2 parts nitrogen gas, which happens to be the approximate composition of the atmosphere.

In theory we could design and use N2O engines and airplanes etc, and their exhaust could be a gas that is nearly equivalent to atmospheric composition.

One important issue is making sure all the N2O has decomposed because it is a very potent GHG.

Would N2 and O2 create contrails? in what sense is it distinct from atmosphere?

Re: Eliminating contrails from flying could be cheap

#102
post #93
post #85

Earlier quoted context omitted.

It was urgent 40 years ago.

No. Addressing CO2 production was urgent then but the actual impacts of heat were not. They are now.

But the warming started already back then. Contrails contributed. So less contrails, less warming in the last 40 years.

Re: Eliminating contrails from flying could be cheap

#104

It'd be worth it just to shut the chemtrail nuts up.

"The government conspired to reduce our cloud cover! Aaaaaa"

"Without those clouds the alien mind control rays from space will get you more often. You think it's deja vu don't you? Better get your tinfoil hat prepped."

Re: Eliminating contrails from flying could be cheap

#105

Earlier quoted context omitted.

This seems pretty useless in an age with super cheap 8k cameras and novice ability to do a delta-recorded image.

If it were all that simple would you not expect at least one of China, Taiwan, Iran, Israel, Ukraine, Russia to deploy such a technology? To me this recently popular idea that you can just point a load of cameras at the sky to beat stealth is disproved by the lack of such installations. These are fairly motivated actors.

> To me this recently popular idea that you can just point a load of cameras at the sky to beat stealth is disproved by the lack of such installations.

Russia has a 10x advantage over Ukraine in aviation, yet it only uses it to lob guided bombs from safely beyond the Russian border. The anti-air defense far outmatches the stealth of Russian airplanes.

They are not the stealthiest, sure. But there are reasons to think that NATO planes are not going to fare much better.

Re: Eliminating contrails from flying could be cheap

#106

This is something the military, e.g. fighter jets worry about. The altitudes (in a given airspace) that form contrails are briefed as part of "tactical weather". You try to avoid them if able, because no matter how stealthy you are, you are lit up for all to see if you fly at those altitudes.

This seems pretty useless in an age with super cheap 8k cameras and novice ability to do a delta-recorded image.

Numbers don't add up.

If you take a 8K camera with a standard 50 mm lens, its angular resolution is about 20" / pixel.

A 50 mm lens has a FOV of about 40°. It covers a cone of about 0.38 strad. A full hemisphere has 2·pi = 6.28 strad, so we need at least 16.5 such cones to cover the whole area; actually we need likely 20-25 because of imperfect geometry and some safety margins at intersections. We can, of course, mount fewer and scan.

If we take a plane like A320 (larger than a typical fighter jet), and remove it 25 km from us, its angular size would be about about 5', or 300". Our A320 would be 15 pixels wide, assuming very good optics, and very clear skies. This is not much to determine what craft is approaching us. At the cruise speed of 800 km/h, or 220 m/s, the plane will reach us in 122 s, or less than 2 minutes. Not a lot of warning. A fighter jet making 500 m/s would be there in 50 s.

This is, of course, without any clouds. Even very light clouds or haze would conceal the aircraft at 25 km. To say nothing of the night time.

We could of course take in IR camera, but I don't remember 8K IR cameras being cheap, or even available. A stealth aircraft like B-2 does a lot to make its thermal signature very faint, including the exhaust.

Re: Eliminating contrails from flying could be cheap

#107
post #76

Earlier quoted context omitted.

If you're ever in DC, you should check out the ads in the metro stops near the Pentagon. Seeing those kinds of ads in real life is even more shocking.

Walked into a weapons show a few decades ago that had a full scale Abrams tank + demo camera providing good 360 degree visibility. It was odd because I was like yea this is obviously a good idea, but also I’m not the person you need to convince here so WTF.

How'd you find a weapons show? Which one? are these semi-open to the public? Sounds fascinating

Re: Eliminating contrails from flying could be cheap

#109

N2O (laughing gas) is not combustible, but autodecomposes into a mixture composed of 1 part oxygen gas and 2 parts nitrogen gas, which happens to be the approximate composition of the atmosphere. In theory we could design and use N2O engines and airplanes etc, and their exhaust could be a gas that is nearly equivalent to atmospheric composition. One important issue is making sure all the N2O has decomposed because it…

N2O formation enthalpy is just 82kJ/mol. For comparison, water is 240kJ/mol.

It doesn't sound so bad, but when translated into grams, it's 1.86kJ/g for N2O and 13.3kJ/g for water.

In other words, when burning a gram of hydrogen, you get about 120kJ of energy. When decomposing a gram of N2O, you barely get 2kJ.

Re: Eliminating contrails from flying could be cheap

#110
post #99
post #96

Earlier quoted context omitted.

What do you mean by delta-recorded image?

The fixed resolution of an image sensor can be augmented by capturing multiple frames over time. https://www.ipol.im/pub/art/2023/460/

Super resolution is a thing but I think they mean to just take the differences and track based on the motions in that data directly. Any deltas which appear to move in a certain way are likely to be aircraft, especially if the same deltas show up on a 2nd camera, even if they aren't clear enough to directly identify. Basically the motion vector estimation step of video encode but tuned really tight and ignoring motions that don't look like aircraft motions.

I'm not sure this is really all that perfect/foolproof though, especially with 8k visible light cameras. For one, clouds can be quite the problem (even at non-visible wavelengths). Atmospheric turbulence can also be annoying and the air can be plain hazy depending on the day - both limit detection accuracy at a given range. When night comes the detection ability is greatly hampered even with additional wavelengths (and IR has lower resolution anyways).

It worked well enough in a weekend project many years back to use computer vision (the craze at the time) and compare to an ADS-B make by using a 4k 1 FPS image feed in a weekend project to mess with computer vision a decade back. I definitely see it as a valid addition to a detection system... but I would stop short of writing a "Military Dumbfounded at This One Simple Trick" article about it.

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