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Comment by tristanj | Hacker News Reader

Shahed drones have increased in altitude from ~500m at the beginning of the Ukraine war to 2000-3000m, which is a 4x reduction in noise on the ground. The higher the drones are, the less noise they make at ground level, and the less effective this ground-based microphone system will be. The drones have moved to elevations to make them more difficult to target with ground based weapons. Reductions in ground noise are a secondary effect.

The latest versions of Shahed can reach 5000m in altitude, which would largely be inaudible on the ground.

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At those higher altitudes they are trivial for radar to detect, and from farther away too. They are adapting cheap commodity used marine radars to get this done in some places

I suspect the Shaheds are going higher to mitigate AA ground fire. Higher up you have to send a missile or interceptor up.

It’s a trade off.

And interceptors are more expensive than Shaheds. A $100k interceptor (guessing here) to shoot a $10k Shahed can be an acceptable deal for the side launching the Shaheds.

Interceptor in this case refers to reusable aircraft. They are sending up cheap to operate prop planes to intercept Shaheds in Ukraine now.

Sending up a plane that costs $500/hour to operate to take down a few Shaheds an hour works out really well.

YouTube has plenty of videos of these guys going up and just shooting them out of the air.

Reusable interceptor has BOM of 3000$, 15000$ sales price. Wanted to start this project with an ex-colleague, but he bought old house and is stuck trying to make it livable.

Anyone interested in cooperation? I am hardware and math guy.

maybe this is a stupid question but how could you possibly re-use a thing that explodes in use

Multiple shotgun shells mounted inside of flying platform for final product. For prototyping it is regulatory nightmare in Germany though. That’s a trade-off reusability vs. hard hit. I took Rheinmetall’s calculation of 1000€ for single piece of their magic anti drone munition for business case.

In some cases they are literally flying small prop aircraft and shooting Shaheds down with a rifle from the cockpit, almost like WWI.

I've also seen videos of drones equipped with shotguns shooting down drones, but those seem to mostly be smaller drones, not long range Shahed drones.

In either case, both are examples of re-usable interceptors, manned and unmanned.

Interceptors can just be an aircraft that goes up and sends a munition at the target.

Think of fighters going up to intercept bombing missions in wwii.

A $100k interceptor to save a $10 million critical facility against a $10k Shahed is a bargain. You saved $9.9 million dollars.

Interceptor economics makes more sense when you reason about the bigger picture. The point is to buy you time to remove the supply chain and the stocks so that you're not trading 1:1 forever. It's a stop-gap, or at least it's supposed to be.

However that only works in a war where you have air and informational superiority. In a peer-like conflict with information asymmetries and air parity (no way to remove the opponent's industrial base), such as Ukraine-Russia, the intercept economics are less appealing.

With interceptors that cost the defender $100k/unit and shaheds that cost the attacker $10k/unit, over time the attacker can bankrupt the defender if the target is something the defender cannot afford to lose. Sometimes it takes several interceptors to eliminate the threat. Therefore part of the focus in the design of interceptors is to keep their unit cost low. The unit cost of the first versions of shaheds may have been $10k; more recent models that fly higher, are equipped with a jet engine, more sophisticated electronics, cameras etc. are significantly more expensive. To the point it's not clear to me, of Ukraine or Russia, who pays the higher price during a mass attack at the moment.

Yes, unit costs should be kept as low as possible. My point is that not all wars are wars of attrition with air parity, which is where interceptor economics make the least sense.

No worries, europe will print money to subsidise ukraine forever.

A $100k interceptor to save a $10 million critical facility against a $10k Shahed is a bargain. You saved $9.9 million dollars.

Your enemy probably isn't sending one drone.

> A $100k interceptor to save a $10 million critical facility against a $10k Shahed is a bargain. You saved $9.9 million dollars.

Sure until they send 200 Shaheds at a night. Another another 200 next night and so on.

Hence the second paragraph

Ukrainian P1-Sun interceptor FPVs were built specifically for this purpose. They are way cheaper than a Shaheed drone and have a practical ceiling of 5000+ meters according to wikipedia.

https://uk.wikipedia.org/wiki/P1-Sun

It's not about "can reach", it's fairly easy to get them to fly even higher. It's about danger of interceptors vs danger of detection. Today's Ukrainian detection network (based on radars) is so dense there is no way to hide from it anywhere, anyway, so high altitude wins.

> It's about danger of interceptors vs danger of detection.

What's with that "vs" trade-off?

You're saying avoiding detection requires high altitudes.

What do interceptors have to do with that?

Interceptors are battery powered and their energy budget and thus range suffers if they have to climb high.

Detection is facilitated by radar, low altitude means flying under the radar (due to curvature of the Earth) - except radar network is now so dense, it in practice can't work anymore. So they can fly low or high they will be detected anyway - but flying high reduces interceptor's reach and makes intercept geometry harder, giving them better chances to slip through.

https://en.wikipedia.org/wiki/Sting_(drone)

The distance to the horizon at sea level, is 5km, a high flying drone only increases that.

With a 25k range and a 10k ceiling, and a stupid low unit cost it is dead easy to deploy this en mass to protect vital infrastructure and deny lower visibility routes (valleys, places where detection range is short).

They (Ukraine) are heavy users of YOLO (image model) that runs on some very low end hardware (sub .35 watt for the most efficient models) - and have shown it to be effective for terminal guidance.

The US has a budget item for 2027, DAWG (defense autonomous war group) - that requested 54 billion dollars. This is larger than the USMC's entire budget. This is a quite admission (another one) that the US is far behind, and the things that are going on in the Ukraine are, terrifying.

> ~500m .. to 2000-3000m, which is a 4x reduction in noise on the ground.

Radiative power drops by the square of the distance? Does anyone with a real physics background start demanding authority on a soapbox like this?

Could you simply use small cheap balloons with microphones to listen in higher altitudes? Or even small drones that carry the microphones with their own engine noise masked out?

Edit: as others say, plain radar will suffice.

So film the sky during charging and run a llm on it?

Or an image detection model. Fraction of the compute and can run even on edge embedded. And easy to train with your own data

Or something like this https://www.youtube.com/watch?v=YZkLQsv3huo

Clouds and nighttime are a barrier to visual detection. Even with good effectiveness the conditions needed for that would mean that you have far less than 50% uptime, and your downtime is predictable to your adversary.

A cheap radar takes an order of magnitude less power to run on hardware that is cheaper than an LLM and can see way farther than a camera.

Radar can't effectively see the new low-altitude small fiber optic spool first-person drones that are redefining frontline war.

The solution is going to be multi-modal (optical + audio) and imperfect. The above poster is correct that an ordinary camera with computer vision (not an LLM, of course) is going to be part of the multimodal defense in depth.

Shahed-type one-way attack drones are important to defend against, but not as impactful in terms of frontline body count, given they just slam into a pre-programmed target.

My comment was about Shaheds like the article we are commenting on.

for what you are talking about, audio is a great option

The article and this thread are about shaheed style drones.

As far as I know, stopping fiber optic fpv drones leans more on physical barriers that catch the fiber (eg road nets) rather than trying to detect and destroy the drone. It’s usually too late by the time you can hear or see a drone that size.

> It’s usually too late by the time you can hear or see a drone that size.

What does the asymptote looks like as defender and aggressor keep iterating. Who has the advantage? Can optical technology get so good at detecting (at least when it isn't raining) that eventually the balance shifts in favor of the defender?

Language models are terrible at computer vision. I don't know why you think that a software to generate words would be able to see flying objects in a picture.

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