Eliminating contrails from flying could be cheap • Hacker News Board

Re: Eliminating contrails from flying could be cheap

#201

Post by Xss3 » Wed, Oct 08, 2025, 10:53 PM UTC

nine_k wrote: post #200

aeternum wrote: post #194

Earlier quoted context omitted.

I agree the attacks were successful, I just don't agree they were successful because of lack of detection. You generally can't continually launch a even $1mil missiles at $100-$10k drones and expect to win. The problem is that most air defenses were designed in an age where the enemy aircraft were quite expensive so it wasn't so critical to optimize ordinance cost. That IMO is the primary challenge for all militaries…

You don't need a missile. Any fighter jet is equipped with a cannon; a bunch of 30mm fragmentation-action ammo would dispatch the drone. You don't need a jet; any decent piston-engine trainer plane can fly 4x as fast as the drone, just mount a machine gun on it. Hell, take a civilian helicopter, shoot through the open door. You have ten hours to dispatch it, given that you have detected it. But, since this is not bei…

Ukraine solved this even cheaper than cameras. They have an enormous microphone network listening for drones and cruise missiles.

Re: Eliminating contrails from flying could be cheap

#202

Post by nradov » Wed, Oct 08, 2025, 11:55 PM UTC

nine_k wrote: post #200

aeternum wrote: post #194

Earlier quoted context omitted.

I agree the attacks were successful, I just don't agree they were successful because of lack of detection. You generally can't continually launch a even $1mil missiles at $100-$10k drones and expect to win. The problem is that most air defenses were designed in an age where the enemy aircraft were quite expensive so it wasn't so critical to optimize ordinance cost. That IMO is the primary challenge for all militaries…

You don't need a missile. Any fighter jet is equipped with a cannon; a bunch of 30mm fragmentation-action ammo would dispatch the drone. You don't need a jet; any decent piston-engine trainer plane can fly 4x as fast as the drone, just mount a machine gun on it. Hell, take a civilian helicopter, shoot through the open door. You have ten hours to dispatch it, given that you have detected it. But, since this is not bei…

Correct, and Ukraine has been doing exactly that with using simple trainer aircraft to shoot down drones.

https://www.twz.com/air/this-is-how-ukrainian-yak-52-crews-h...

The Russian air defense radar system has been badly degraded by recent Ukrainian strikes. They have been conducting a deliberate SEAD/DEAD campaign to clear the path for strikes on strategic targets. Of course the Russian air defenses everywhere far from Moscow were probably never very effective in the first place due to the usual mix of poverty, corruption, vodka, and incompetence.

Re: Eliminating contrails from flying could be cheap

#203

Post by klodolph » Thu, Oct 09, 2025, 4:25 AM UTC

topaz0 wrote: post #142

klodolph wrote: post #111

Earlier quoted context omitted.

Someone can break out their chemistry references, but I think N₂O is probably not workable as a fuel (or at best, not very good). It forms naturally in internal combustion engines, from air, at the temperature and pressures found in engines, given O₂ and N₂. If something has the habit of forming in an engine, I don’t think you could use it as fuel, but my thermodynamics is a bit too rusty to do any kind of ELI5 and I…

You're probably thinking of NO2, which is indeed a pollutant that results from overly hot combustion in air. N2O is in fact used in engines, but it is not the fuel -- rather it is a supplementary oxidizer, which allows you to burn more fuel and therefore produce more power than you could if you only had the oxygen from air. At any rate, that means using N2O won't be a solution to the aircraft fuel problem -- you'd st…

Damn, yes, I mixed those up.

Re: Eliminating contrails from flying could be cheap

#204

Post by Tor3 » Thu, Oct 09, 2025, 6:42 AM UTC

overfeed wrote: post #192

Tor3 wrote: post #146

Earlier quoted context omitted.

"Clouds also don't save you (unless you have two thick layers to fly through) because this technique is even easier with satellites." This is incorrect. A typical satellite will orbit once every 100 minutes or so (military spy satellites more often because they fly lower, but that only makes the next part even worse). To have any kind of resolution the swath it can scan is very narrow. It'll pass from horizon to hori…

> A typical satellite will orbit once every 100 minutes or so (military spy satellites more often because they fly lower, Constellations (like Star Shield or the Chinese equivalent) solve this problem; there is always a dozens of satellites overhead, and they don't need a lot of resolving power to detect contrails, I vet even cubesats with repurposed phone-camera sensors would suffice.

contrails can be detected, at least when they disperse a bit. And as they linger it's even easier. What's difficult anyway you look at it is to detect the actual airplane, at the point where it's at at the moment.

Note that the Starshield satellites aren't able to cover all of the earth all of the time, far from it.

Re: Eliminating contrails from flying could be cheap

#205

Post by steanne » Thu, Oct 09, 2025, 12:38 PM UTC

anon98356 wrote: post #173

stevage wrote: post #81

Earlier quoted context omitted.

The article addresses this in detail.

It covers the impact of fuel quite thoroughly but it brushes over the time element which I think is actually a bigger factor in why they don't really do it. Passing on the fuel cost to the customer they could probably get away with but given how tightly packed the flight schedules are (particularly short haul) the cumulative extra time across even a day could be enough that they have to drop a flight from the schedul…

adding a little extra time doesn't necessarily break the schedule. often when i've flown we've arrived early due to favorable winds.

Re: Eliminating contrails from flying could be cheap

#206

Post by overfeed » Fri, Oct 10, 2025, 6:51 PM UTC

Tor3 wrote: post #204

overfeed wrote: post #192

Earlier quoted context omitted.

> A typical satellite will orbit once every 100 minutes or so (military spy satellites more often because they fly lower, Constellations (like Star Shield or the Chinese equivalent) solve this problem; there is always a dozens of satellites overhead, and they don't need a lot of resolving power to detect contrails, I vet even cubesats with repurposed phone-camera sensors would suffice.

contrails can be detected, at least when they disperse a bit. And as they linger it's even easier. What's difficult anyway you look at it is to detect the actual airplane, at the point where it's at at the moment. Note that the Starshield satellites aren't able to cover all of the earth all of the time, far from it.

> What's difficult anyway you look at it is to detect the actual airplane,

Contrails tell you when and where to look with more paranoia than usual, and temporarily lower the noise floor and not to disregard the some signals that you'd normally classify as a small bird.