chrisl

Wavelength can be anything you can make a laser with, all the way out to microwave, where it becomes SAR. LiDAR is typically visible or near IR, so 400 nm to 1550 nm. There are a few wavelengths in that range that are popular because they’re mass produced lasers (532, 1064, 1550 nm)

Seems like a clever Ukrainian could write an app that people can leave running on their phone when they aren’t using it that uses the mic to pick up shahed engine sounds and transmits time & location data to a server that tracks them similar to MLAT mode for ADS-B. Phones wouldn’t have to be fixed location or dedicated, just a lot of them listening at any time.

I'm not sure it's a limitation intrinsic to drones, so much as the current implementations, and particularly the Russian implementations. I think it falls under @The_Capt's scalability and communication parts of precision. In a sense you can consider the conscripts on the ground as Russia's version of dumb drones with poor comms and integration - they can see what they can see, but they can't relay it anywhere and they aren't under any kind of consistent command and control for scouting particular areas and reporting back information to integrate. They sometimes have scale (a bunch of conscripts) but they're missing the rest. When things come together for Russia, they can use drones effectively for calling in and correcting arty to at least the precision and accuracy of their guns. The thing that's missing is their ability to do this at scale. It's possible to do at scale if you have a lot of drones with good comms and integration. It's even arguable that a a system like that would let you see below the tree canopy as well as or better than boots on the ground - a compact drone with multispectral imaging can see over that next rise, or quietly cruise through the upper levels (or on the ground for a UGV) of a forested area to scout things out and relay information back better than a person whose eyes are 6 or 10' off the ground and limited to walking speed. And you can make a lot of them cheap and not feel too bad when they're destroyed.

I thought that was just the military command that they moved onto the left bank when the bridges were taken out. They left the civilian "leadership" to face the Ukrainians and the surrounded conscripts. Watch for Ukraine to already have a couple brigades staged on the left bank who will com around behind Kherson while their forces on the right bank draw the right-bank Russians out to the perimeter with a feint.

Exactly. Precision has at least three key components: Knowledge, Control, and Time, and you need all three, and just about everything "precision" Russia is using is deficient in all three areas. Knowledge is the ability to know where your stuff is and where your target is. With functioning GPS you can know whre your stuff is to a meter or so without a lot of difficulty. There are other ways as well. You can use knowledge of your own stuff's locations to use it to figure out where your targets are. Russia has some ability to get precision knowledge with drones, but it's less reliable than the ISR web that Ukraine has available. Once you know where your target is, you have to have something that you can control with the same precision (and implied in that is accuracy, as well) to get your rockets and artillery shells there to hit it. Russia really suffers here. None of their "precision" stuff seems to have anything vaguely like modern precision control - the can sometimes hit power plants, which are not small targets and don't move around. The last element is time. You need to be able to respond with your precision control within some time frame where you still have precision knowledge of where the target is, rather than where it was. This is where all the RU cruise missiles/buzz bombs/drones really lack. They're slow, so they can only target things that can't move, even if they had 1 m precision and accuracy. You can make up for time by doing things like using precision to get you to the neighborhood and autonomous guidance to find the target's current precise location. Anti-ship missiles do this, as do some of the clustered AT bombs/missiles. With HIMARS, the crew can get a call, drive out to a new launch site, launch, and be drinking tea at a new location before the missile lands. If you don't have all three, you can't hit anything that can move around unless you just get lucky.

In the grand scheme of things, the V1s weren't a whole lot larger - the wingspan of the V1 was 5.7 m, and the Shahed is 2.5 m. So a little less than half the size. If they have a very distinct acoustic signature the balloons could trigger on the sound, rather than depending on contact with the tethers.

Anti-drone drones seems like the most reliable approach. A big piece of capital equipment, whether directed energy or kinetic, is just a big target, and once it's gone the opponent has free rein over the area. Anti-drone drones can be cheaper than attack drones - they don't even need to have any kind of weapon other than themselves, and have the option of being explody or not. A bunch of kevlar string can foul propellers - they can dangle strings or throw nets like gladiators, and one drone could carry multiple "fouling weapons". They can run entirely autonomously once launched - if they don't need comm then they can't be jammed. The tricky part is having an IFF system that works effectively (and isn't spoofable) in swarms where there might be a mix of friends and enemies.

Don't we all?

It sounds scarier. Like the "Phoenix Ghost" drone - it's got an ominous name and there's no information on what it is, so it's scarier than if someone said "we put hand grenades on RC airplanes with inertial guidance systems"

So do they show up on radar or is it just visual identification? I suppose it might be better to keep ambiguous for now how they're being spotted and stopped, but it sounds like there are fairly effective defenses around Kyiv if ~75% are being stopped before they get there. And they must move slow if police are able to hit them with rifles. Based on the photo of the one in the policeman's hand, they're smaller than I expected - I had the impression they were much larger from the launcher photos. Now that there are probably a bunch of pieces available for analysis, hopefully the shootdown rate will get closer to 100%.

Out a window?

Nothing in my post was intended to attack you, but I don't think the numbers that Musk kicks around are correct. Or likely even close to correct. And the only number I picked out was the $4500, not the 85%, because either Musk or the press like to keep saying "our most expensive service is $4500/mo" without detailing how many terminals in Ukraine are getting that service vs the $100/mo service. If you give someone something that you charge for that *they* otherwise would pay for, then you're reducing your income by that much. But what it costs you is only what it costs you, especially if it doesn't use enough of your capacity to limit your sales to other people. When the USG is buying something in bulk (like internet service from a satellite provider, for example), they often negotiate prices that are based on actual cost+reasonable profit rather than some published retail price. Retail prices are often structured in funny ways, like printers below cost and overpriced ink, cell phones sold below cost with high priced service, or Starlink terminals below cost+overpriced service, where the price structure is designed to make the barrier to entry low and then make up the loss on the high priced service. The government might reasonably choose to pay full cost for the terminals and then pay cost+agreed profit for the service. All I was trying to do in my post is point out that Musk is likely *way* overplaying how much the service to Ukraine is costing Starlink, that there are a lot of people and organizations paying for Starlink service in Ukraine, and that it's very possible that they'll be made whole in the end anyway.

$4500 is the most expensive service they offer. There's nothing that says there are 25K devices getting that service. And that's retail price, not cost. Actual cost of providing the service could be a small fraction of that. I was just reading an article in WaPo a few minutes ago that USAID paid $1500/ea for a bunch of "standard terminals and service". There are also bunches of Ukrainians posting their monthly invoices for the standard service they're paying for. Many people are paying for service on multiple terminals. When I was looking up the cost of a satellite, some of the articles showed SpaceX's own projections of revenue from Starlink. My guess would be that a substantial fraction of the service being provided in Ukraine is paid for by a variety of sources: US gov't, other gov'ts, individuals, and SpaceX. If SpaceX is demanding payment for service that wasn't contracted, they're also asking for DCMA to visit and see how much service they've actually been providing that isn't paid for by some other source, and it will probably turn out that it's not costing them all that much, and the bad press that Musk is trying to get will cost them more just providing the service, which is in some sense some of the lowest cost advertising they can get "hey, you think your application is demanding? Ukraine used our stuff in a war zone to defeat Russia" (and they don't even have to say it). Someone inside SpaceX knows the numbers and from some recent tweets it sounds like they got through to him and told him to shut up. And its entirely possible that in parallel there are contract negotiations going on that will fully cover the costs. But whoever gets that taken care of won't go advertising it on twitter, and the USG will probably keep it quiet as well, possibly even as part of the deal.

It's not a wasted attack with a one-off truck bomb. It still will slow down transport across the bridge by both rail and truck since they have to crank up inspections. And it's not like they're going to be efficient about inspections - they haven't shown any efficiency in logistics since Feb. And if they don't crank up inspections they'll get bombed again. The rail bridge may also have some pretty severe hidden damage. At least one discussion of it I saw claimed that it's ballast in a steel pan, rather than reinforced concrete. If it's true, it probably heated up the steel much faster than it would heat through concrete, and the segment that had the extended fire would be very weakened and susceptible to deformation and eventual failure if they run heavy trains across it. Unfortunately the bridge construction doc that was linked a few days ago only has detail on the road bridge, not the rail bridge, so I haven't seen if it's true about the ballast-in-a-pan thing.

There are almost certainly a bunch of program managers at SpaceX/Starlink who aren't absolute nutters who have been on the phone with their DOD contracting, launch-approving, and export reviewing counterparts doing whatever damage control needs to be done (probably not all that much). Musk can say whatever random stuff he wants to say on twitter, but the people in the background actually do all the contracting and government interaction and both sides know how things work.

Not just technically - also economically. The USG already could put whatever performance they wanted into space for vast amounts of money. Starlink is very commercially viable. The government basically already did what you suggested - Iridium cost about $5B to put into space and there wasn't enough market to pay to operate it and pay whatever debt service they had. It got picked up at a fire sale price of tens of millions, like a space version of the Pontiac Silverdome, by a company that was at least initially basically reselling service to the DOD. It was a bargain for DOD - the hardware was already in space, so all the cost and technical risks were gone, and they just had to put enough money in that the buyers could continue to operate it while they looked for other customers. Starlink really needs to stay private because there are a ton of non-DOD applications for it, and it looks like it works economically. The only real issue is that Musk is a nutcase.

The satellites themselves are actually *very* cheap. A few articles are suggesting costs in the $250K/unit cost, with launch costs of $30M or less per block of ~50 satellites. There's a bunch of ground costs on top of that, and I'd guess that the limiting factor on subscribers is bandwidth to the fat pipes on the ground. They could probably sell quite a lot more subscriptions if they let performance degrade somewhat, but it's probably better for them in the long run to maintain a high level of performance over a limited number of areas so that as they open regions they get big blasts of subscribers. I suspect a few things: 1) Elon has no clue about the details of the economics of them supplying Ukraine with bandwidth. He's a loud AW who says all sorts of random things that may or may not correlate to reality. It's common for engineers at his companies to found out about new "requirements" from his public tweets. That they can deliver on a lot of them is a testament to their engineering capability and willingness to work in the chaos. 2) Starlink is raking in money and even if they're taking a loss right now, they aren't going to go the way of Iridium. Iridium was a nice idea but was too early and had too limited capability - there wasn't enough demand for poor phone service over the vast amounts of unpopulated space on the surface of the earth. There *is* demand for high bandwidth data connections in the middle of nowhere. I've actually dealt with trying to debug hardware that was near the north pole while I was in California. The people with the hardware had an iridium phone and they could call, or they could email, but they couldn't do both - if we wanted a picture of something, they had to hang up, create a data connection, send (slowly) then call back. At probably a buck a minute or something. If they'd had 10 Mbps for $100/month it would have been a *lot* less painful. There's a lot of inexpensive environmental monitoring equipment that you can put out in the middle of nowhere that's cost effective at Starlink prices. Or even a few times Starlink prices. 3) People don't talk about it, but Starlink has the potential to offer to high school kids building cubesats a capability that was until recently really only available to the US government (SDS, TDRS). The data relay system was arguably a bigger secret (and easier to keep secret) than the KH-11 telescopes (although their digital imaging that took advantage of the SDS was also secret). Anybody who's ever read the first couple chapters of an optics text can figure out the resolution possible with a telescope of a given size at a particular distance, but the data rates and speed of return are a big deal. Starlink can potentially sell space nodes to anybody building a satellite and they can get realtime, high bandwidth data returned to the ground for a few hundred $K. That's going to be a very valuable market.

You want them to smell it. Where's the T-72 chassis with big fans mounted on top to waft the odor of hot cooking over to the Russian lines?

I don't think pigeons are really big enough for a proper HEAT round. A Canadian goose seems more likely.

Bombing a fuel tank car on a train would take less explosive but be harder to hide on the tank car. Ideally you'd want a two stage explosive inside the tank - one to blow open the car and create a mist, the second to ignite it, like a big FAE. Many liquid fuels by themselves don't blow up that well in bulk liquid and you have to create a mist. Maybe it would have been enough to blow open a car and have it start a fire with oil burning all over the bridge (as happened by luck, anyway). Hiding it in the truck is easy: You put it in a big crate, fill out a shipping form, and leave it on the loading dock. And it had the effect of shutting down the bridge, even without destroying it - they got Russia to shut it down and create a big mess for getting into/out of Crimea via Kerch. And as @billbindcpoints out - there's some pretty good messaging in there for Russia, too. Before the invasion I was n the "they'll roll over Ukraine in 3 days and it will be 10 years of Afghanistan before they leave" camp. Had that happened, basically all of Ukraine's attacks would be looking like this now. Instead they sent a message that's almost like the laws of thermodynamics: a) You can't win b) even if you think you can fight to a draw, you lose, c) You can't quit if we don't let you.

We need to take all the theories from here and elsewhere, work them into a movie script, and get it shot and released before the mundane true story gets out.

I thnk you'd want it to be something recoilless for most of them, but it would be cool to see what you can do.

Antonovsky Bridge is reinforced concrete. They still build structures like that around here, but it's taking about 3 years for the construction (not including surveys, design, engineering and prep) of a 2.35 mile elevated people mover at LAX. I think all the columns were poured in place and the deck is all pre-fab. And it's all tied to bedrock, and they've kept the airport open the whole time and managed to speed things up because of the reduced traffic during the apocalypse.

That road section makes it look like there's some rebar inside the pavement, but the picture of the face of the deck where the pavement has come off just like smooth sheet steel underneath. It also wouldn't make any sense to put rebar inside asphalt, which is what most of the road surface is. Are there some concrete segments?

I agree his analysis is pretty good. But so far it's clear that all the explody and structury people have never put a camera in a vacuum chamber with a strobe light and a water spray. Little droplets can be very bright. The structure of the bridge is why only that one edge is bent down on the adjacent deck. Each deck looks like it's basically a sheet of thick steel, like the steel plates your local road department uses over trenches, laid across a bunch (looks like 10) of longitudinal box-section beams that run parallel to the road. At the outer edge of each deck, outside the big rails that support the struts linked to the cross-beams, there are two smaller stiffening elements that look like they're just long strips of plate, probably the same thickness as the deck and not nearly as tall as the big boxes. Those will have very little lateral rigidity compared to the box beams. The picture from underneath shows this well. When the pressure wave hit the adjacent deck, the asphalt has very little strength in tension as it's getting blown up like a balloon. The shock front is moving fast enough that the air can't get out of the way fast enough to "roll" across the span and it stays a spherical shock front. The asphalt isn't very strong in tension, so it doesn't do much to keep the steel underneath from flexing, and the load is coming from an angle that the road wasn't designed for - the shock front hits it like a big ball bearing from up and to the side, so flexes the deck down and the smaller vertical "rails" more sideways, where they have no strength. The combination of a stiffer deck and further distance from the center of the explosion makes the bending less dramatic once you get in a little ways from the edge. And while I'm still in the truck camp, I won't totally rule out a missile (though there don't seem to be any missile parts around). The explosion seems to have come from the left side of the truck, possibly from something that wasn't sitting on the floor of the truck (about 2m off the deck). It could be that the explosive was stacked up, but it could also be that a missile hit the upper left side of the truck. Given the bridge construction, I suspect people are overestimating how much HE it would take to flex it in the middle enough to pull the ends in and let gravity do a lot of the work.