5 ms·

A quick glance shows that gliders can manage a glide ratio of 15:1 meaning that a set of glide drones dropped at 60k feet could at least hypothetically reach 17

by lumost 5y ago

A quick glance shows that gliders can manage a glide ratio of 15:1 meaning that a set of glide drones dropped at 60k feet could at least hypothetically reach 170 miles. ( The practical calculation for this is much much more complex ). There is no reason the drones couldn't wait to start their engines until they are at the ~40 mile line after being dropped at the edge of the CAP patrol. EDIT: it looks like a good glide ratio is 60:1 meaning that the above scenario could play out outside the effective radar range of the carrier group, and hundreds of miles away from the CAP patrol.

robkop 5y ago
Unfortunately to maximise glide ratio you are going to want to maximise wing surface area which isn't really optimal for both having the ability to deploy mass drones and for radar cross section.
- Robotbeat 5y ago
  You maximize surface area if you want to minimize sink rate. Glide ratio is a different beast, where you want long and thin wings. Glide ratio is fairly independent of speed up to Mach 0.5 or so, so you’d want to maximize wing loading to go fast.
captainredbeard 5y ago
Carrier group will be operating with an AWACS or similar expanding radar range. A large plane or a swarm of smaller things would light up modern radars from a distance easily. Nuclear tipped missiles will be the response.
- NovemberWhiskey 5y ago
  >Carrier group will be operating with an AWACS or similar expanding radar range e.g. the E-2 Hawkeye, which is carrier-embarked, launches from the catapult, and (in modern variants) includes a surveillance radar that will detects threats out to 300 nautical miles and beyond.
cgearhart 5y ago
In order to weaponize it you’ll probably need to add a high explosive payload, and ships are pretty big targets so you probably want at least a couple hundred pounds of it. Probably need some smarts onboard to keep it gliding autonomously all that way, too. Of course, if you’re aiming at ships, then those will move while you glide there so maybe add some sensors so it can do terminal guidance when it reaches the target area. It would be expensive and take a lot of battery power for every glider to have sensors that can reach 100’s of miles to track the target, and they’d always be blown up at the end of the trip (which seems wasteful), so maybe we can network the weapons and broadcast course corrections to them along the way. We’d hate for the targets to see it coming too early and shoot back, so low observability would also be nice. Of course, all this is starting to sound expensive…and if we’re gonna buy something like that, then maybe it should have a long shelf-life and we should be able to periodically inspect and maintain it so that when we finally use it after 30 years on the shelf, it works exactly as intended. It doesn’t really sound much like a drone anymore though, more like some kind of “glide bomb”. Hey! Look at that: https://en.m.wikipedia.org/wiki/AGM-154_Joint_Standoff_Weapon https://en.m.wikipedia.org/wiki/AGM-154_Joint_Standoff_Weapo... (FWIW, I mean this in jest, not condescendingly.)
- lumost 5y ago
  Looks like the Naval variant costs around 720k, with more baseline variants running ~340k. Considering the weapon was designed in the 90s I'd be curious if a modern version could be done for less money with off the shelf components. Given that China's military costs roughly half the US's for the same gear this also puts this glide bomb in the cost range where anti-missile missiles start to look expensive.
  - cgearhart 5y ago
    That looks like all up round cost. The per-unit production cost of a weapon is typically much lower, and never really the dominant factor in overall program cost. (Overall costs are dominated by operations & maintenance, followed by R&D.) For example, the FYDP budget request for USN JSOW production shows a flyaway cost of past variants as $225k/unit, and the production cost for C-1 (and maybe -ER, which adds a rocket motor) variants decreasing from $613k to $466k by 2024. (Source: https://www.dacis.com/budget/budget_pdf/FY20/PROC/N/2230_6.pdf https://www.dacis.com/budget/budget_pdf/FY20/PROC/N/2230_6.p...) Most weapons use off the shelf components from the time they were designed, and moving to more modern components doesn’t save enough in production cost to justify the cost of redesign, testing and certification processes. If a 90’s chip was “good enough” to meet spec in the 90’s then it’s still good enough in 2021. (Assuming we’re even still building the 90’s variant and not just maintaining existing inventory.)
NovemberWhiskey 5y ago
First of all, I suggest you go take a look at the dimensions of a modern, high performance sailplane - this is what you're talking about when you describe an aircraft that's capable of a glide ratio of >50:1. They're not heavy, but they are large, and they are cumbersome. For example, a Jonker JS-1 Revelation is a fairly state-of-the-art design manufactured with high-tech materials (including carbon-fibre and Kevlay). It is over 7 meters long and has an 18 meter wingspan, in order to carry a total payload of ~300 kg, which is roughly about where you start for bombs expected to have serious effects on blue-water combat ships. How exactly are you delivering a swarm of these from 60,000 feet?

by lumost 5y ago

robkop 5y ago

Unfortunately to maximise glide ratio you are going to want to maximise wing surface area which isn't really optimal for both having the ability to deploy mass drones and for radar cross section.

Robotbeat 5y ago
You maximize surface area if you want to minimize sink rate. Glide ratio is a different beast, where you want long and thin wings. Glide ratio is fairly independent of speed up to Mach 0.5 or so, so you’d want to maximize wing loading to go fast.

captainredbeard 5y ago

Carrier group will be operating with an AWACS or similar expanding radar range. A large plane or a swarm of smaller things would light up modern radars from a distance easily. Nuclear tipped missiles will be the response.

NovemberWhiskey 5y ago
>Carrier group will be operating with an AWACS or similar expanding radar range e.g. the E-2 Hawkeye, which is carrier-embarked, launches from the catapult, and (in modern variants) includes a surveillance radar that will detects threats out to 300 nautical miles and beyond.

cgearhart 5y ago

In order to weaponize it you’ll probably need to add a high explosive payload, and ships are pretty big targets so you probably want at least a couple hundred pounds of it. Probably need some smarts onboard to keep it gliding autonomously all that way, too. Of course, if you’re aiming at ships, then those will move while you glide there so maybe add some sensors so it can do terminal guidance when it reaches the target area. It would be expensive and take a lot of battery power for every glider to have sensors that can reach 100’s of miles to track the target, and they’d always be blown up at the end of the trip (which seems wasteful), so maybe we can network the weapons and broadcast course corrections to them along the way. We’d hate for the targets to see it coming too early and shoot back, so low observability would also be nice. Of course, all this is starting to sound expensive…and if we’re gonna buy something like that, then maybe it should have a long shelf-life and we should be able to periodically inspect and maintain it so that when we finally use it after 30 years on the shelf, it works exactly as intended. It doesn’t really sound much like a drone anymore though, more like some kind of “glide bomb”. Hey! Look at that: https://en.m.wikipedia.org/wiki/AGM-154_Joint_Standoff_Weapon https://en.m.wikipedia.org/wiki/AGM-154_Joint_Standoff_Weapo... (FWIW, I mean this in jest, not condescendingly.)

lumost 5y ago
Looks like the Naval variant costs around 720k, with more baseline variants running ~340k. Considering the weapon was designed in the 90s I'd be curious if a modern version could be done for less money with off the shelf components. Given that China's military costs roughly half the US's for the same gear this also puts this glide bomb in the cost range where anti-missile missiles start to look expensive.
- cgearhart 5y ago
  That looks like all up round cost. The per-unit production cost of a weapon is typically much lower, and never really the dominant factor in overall program cost. (Overall costs are dominated by operations & maintenance, followed by R&D.) For example, the FYDP budget request for USN JSOW production shows a flyaway cost of past variants as $225k/unit, and the production cost for C-1 (and maybe -ER, which adds a rocket motor) variants decreasing from $613k to $466k by 2024. (Source: https://www.dacis.com/budget/budget_pdf/FY20/PROC/N/2230_6.pdf https://www.dacis.com/budget/budget_pdf/FY20/PROC/N/2230_6.p...) Most weapons use off the shelf components from the time they were designed, and moving to more modern components doesn’t save enough in production cost to justify the cost of redesign, testing and certification processes. If a 90’s chip was “good enough” to meet spec in the 90’s then it’s still good enough in 2021. (Assuming we’re even still building the 90’s variant and not just maintaining existing inventory.)

NovemberWhiskey 5y ago

First of all, I suggest you go take a look at the dimensions of a modern, high performance sailplane - this is what you're talking about when you describe an aircraft that's capable of a glide ratio of >50:1. They're not heavy, but they are large, and they are cumbersome. For example, a Jonker JS-1 Revelation is a fairly state-of-the-art design manufactured with high-tech materials (including carbon-fibre and Kevlay). It is over 7 meters long and has an 18 meter wingspan, in order to carry a total payload of ~300 kg, which is roughly about where you start for bombs expected to have serious effects on blue-water combat ships. How exactly are you delivering a swarm of these from 60,000 feet?