Even cruise missiles are horribly expensive for conventional munitions payloads. Cruise missiles were developed to deliver nukes.

An unguided 1000kg "dumb" bomb costs $2,000. A "smart bomb" costs $20,000 to $100,000. A cruise missile costs $1mil to $2mil.

In the scope of any protracted real war, sending out lots of cruise missiles is horribly inefficient. Much much cheaper to send out a few planes to drop 100's of tons of dumb or smart bombs. IOW, you can deliver 10x to 100x more boom if you just use planes and bombs. 1000x more if you use long range artillery. But then, the pilots or soldiers are at risk-- and that is a political calculation.

about cruise missiles, wasn't there one of those DARPA contests to see if a guy in the garage could produce a cruise missile? IIRC it got quite scary and was cancelled or something. Being in the drone and high power rocketry hobby i have absolutely no doubt there's enough knowledge and electronics availability for a guy in their garage to come up with something that delivers 50lbs to a precise gps coordinate a few hundred miles away for less than $10k. Once you do that, it's easy to scale up to 500lbs

I'm skeptical you could hit that sort of range for anywhere near $10K. Forget the electronics, you need an engine powerful enough to lift a few hundred pounds for that distance. Unless you want it detected immediately by early warning radar you need it to fly at a low altitude, like a hundred feet or less. Unless you want it to take forever and be susceptible to infantry with small arms it needs to be traveling fast, in the hundreds of miles an hour. That's simply not possible with an electric system with today's technology, and a rocket engine won't provide the endurance or efficiency you need. That leaves a jet engine or pistol engine. Plus, flying at that speed and altitude means you need an effective autopilot system that uses terrain-following radar. You'll also need some nice guidance packages that allow the shooter to set multiple waypoints, so the missile doesn't have to just fly a direct course. And a 50 lb payload of high explosive just isn't that helpful. There aren't a ton of targets where you only need 50lb of explosives to defeat them, that are also going to stay in the same exact GPS position long enough for your missile to travel a few hundred miles. So you'll want a different terminal guidance method, either some sort of radar sensor or infrared.

I don't think you could get an engine capable of getting you hundreds of miles at that speed and altitude, much less the sensors and guidance system.

A lot of the cost in defense contracts is paying for guaranteed domestic supply in the event of a war. If you buy COTS parts and outsource your machining I see $10k as very achievable, the majority of that being metal and explosives. The electronics are nearly trivial, but some of the IR tracking is embargoed and hard to get outside the US.

Find me an engine capable of going a couple hundred miles an hour for less than $10K though

Hydro-formed "Escopette"-style valveless pulsejet? They run as efficiently as a turbojet (w.r.t. specific fuel consumption), and Mach 0.7 is way beyond your "couple hundred miles an hour".

It will be burnt up by the time it runs out of fuel, though.

For a good one it has to be hydro-formed out of seamless pipe, which is likely hot-stretched (like wire drawing, but using an induction heating coil in place of the die, and independently controlling the feed-rate and the pull-rate) in advance to retain consistent wall thickness in the engine despite being cross-section after hydro-forming. Also probably incremental hydro-forming with grain-structure-fixing re-heating between stages.

The hard part is just that most of the work is in making the hydro-forming dies/tools, not then using them to cheaply produce more engines.

Fascinating, haven't heard of this. Some googling suggested there is some active research in this area, and at least some active use by hobbyists and by the military in target drones. Seems like a promising angle for a cheaper cruise missile, at least on the engine front.

They are loud, though, because they use ~100 Hz wave compression for their combustion, instead of continuous-flow as with a non-pulse jet.

A solid rocket engine. It's not hard. Did you mean missiles or drones?

You're going to have serious troubles implementing a cruise missile with a range in the hundreds of miles with a solid rocket engine. While most cruise missiles use a solid booster to launch the missile and get it up to the proper speed and altitude, you need an engine to sustain flight. You also need a propulsion mechanism that allows you to control thrust, which a solid engine wouldn't. To my knowledge there is no cruise missile in existence that uses just a solid rocket engine. In theory you could get into the hundreds of miles with just a booster if you use it to get up to a significant altitude and glide the rest of the way. But that largely defeats the purpose of a cruise missile: traveling at low altitude to avoid enemy radar.

Of course, you can definitely make a BALLISTIC missile with a couple hundred mile range using a solid rocket engine, and probably for fairly cheap (especially if you don't particularly care about accuracy)

> BALLISTIC missile

Also: Scud missiles are comparable, made outside western cost inflation, and still ~$1M each. So I'm guessing you can't get a ballistic missile anywhere near $10k (at least, not one that isn't more likely to kill its owner).

Yeah, I got confused. Those are harder to reduce cost on. I had this conversation previously about javelins, etc.

Well, unscrupulous sellers find a way even around embargoes...

https://disclose.ngo/en/article/war-in-ukraine-how-france-de...

(An order of magnitude larger helicarrier contract was cancelled eventually.)

V1 was 160 miles, 1800lb warhead? You saying a bunch of nerds in 2022 can't beat 1940's tech to bring the price down a bit?

I think they can bring the price down a bit, but not to $10K, even with a smaller size payload. Also I should mention the V1 was barely accurate enough to target a city the size of London. Not that adding modern GPS guidance would necessarily cost that much, of course.

Gliders though.

So you use a solid rocket booster or maybe make it air-launched and have it glide to the target? So that is definitely a thing, an example I can think of is the US small diameter bomb (https://en.wikipedia.org/wiki/GBU-53/B_StormBreaker ) or the JSOW (https://en.wikipedia.org/wiki/AGM-154_Joint_Standoff_Weapon ). Though those aren't in the "hundreds of miles" that OP originally proposed, they are in the 50-75 mile range. Those also technically aren't cruise missiles, and don't have the primary advantage of a cruise missile: the ability to travel at low altitudes to evade enemy radars and air defenses.

That said, you could probably make a glide bomb for pretty cheap. The two examples I gave above are in the hundreds of thousands, but I bet if you sacrificed some of the accuracy and payload, and you were really optimizing for cost, you could get that into the tens of thousands

There was a man in New Zealand trying to make a very low-cost DIY cruise missile as a hobby project [0]. iirc, he was using a pulsejet engine, but ended up getting shut down by some visits from stern-looking government agents.

0: https://www.theguardian.com/world/2003/jun/04/terrorism.davi...

> wasn't there one of those DARPA contests to see if a guy in the garage could produce a cruise missile? IIRC it got quite scary and was cancelled or something.

This sounds similar to the Nth Country Experiment, conducted by the US in the 1960s. The idea was to see if three freshly minted physics PhDs could design a working nuclear weapon using only publicly available information. In less than 3 years, the three succeeded in creating a credible design for an implosion-style bomb.

https://en.wikipedia.org/wiki/Nth_Country_Experiment

> ICBMs are expensive. Probably tens of millions of dollars each

For sub-launched ICBMs (like the UK's nuclear deterrent) you also need to factor in the through-life costs of the launcher platform, and the fact that once it starts launching, it has given itself away. We only have four subs, not all of which are on patrol, so it would be barking to compromise these to deliver a conventional payload.

Submarine launched ICBMs probably wouldn't be valuable without nuclear weapons though: they're valuable because they're a guaranteed second-strike capability to a nuclear first strike - you might plausibly get the land and air launchers, but there's no way to be sure you got all the subs and you only have to miss 1 (i.e. no country would survive losing 28 major cities).

Without nuclear weapons, they're kind of pointless - you don't inflict enough damage to warrant the expense. But the first strike is also so much more survivable.

Which country is "we"? The US has 14 Ohio class SSBNs in service until at least 2029

Probably the UK.

https://www.royalnavy.mod.uk/news-and-latest-activity/operat...

Yes, the UK (I should have made this more explicit).

The UK's current deterrent force is currently expected to be replaced by the successor Dreadnought class [0] in the 2030s. They are currently projected to cost £31 billion (likely an underestimate) for four subs, each of which can carry 8 missiles max. Again, these are a horribly expensive way to deliver conventional explosives when we have cruise missiles instead.

[0] https://en.wikipedia.org/wiki/Dreadnought-class_submarine

> ICBMs have longer range, but how often do you need to strike targets more than 1000km past the front line?

Don't you need to also consider the vast expense countries (okay, mostly just the United States) spend to essentially extend their "front line" well beyond their own borders?

Well the first year of the Iraq War cost the US $54 billion, according to congress's budget[0]. This doesn't include the total cost of the supporting infrastructure need to be able to deploy troops in Iraq quickly, but we can estimate that using the increase in defence budget from 2002-3, or $94 billion ($132B in 2020)[1].

According to Wikipedia, Minuteman III ICBMs have a 2020 unit cost of $20 million[2], so for the cost of an Iraq invasion, the US could have fired about 6600 missiles. Considering the invasion toppled the Iraqi government, it's pretty unlikely that firing 6600 missiles with conventional payloads would have been anywhere near as effective.

[0]: https://en.wikipedia.org/wiki/Financial_cost_of_the_Iraq_War...

[1]: https://en.wikipedia.org/wiki/Military_budget_of_the_United_...

[2]: https://en.wikipedia.org/wiki/LGM-30_Minuteman#Counterforce

The comparison we're making is whether precision attacks, presumably on roughly building-sized targets, would be cheaper to do from long range via ICBMs (with conventional warheads), or via much cheaper but shorter-range missiles. My guess is that neither ICBMs nor shorter-range missiles could have accomplished what the U.S. military accomplished in Iraq. Presumably missiles alone were responsible for a small portion of that $54 billion.

If I can trust https://en.wikipedia.org/wiki/LGM-30_Minuteman a Minuteman III (which is the current ICBM design used by the US) will land within 800ft (240m) of its intended target 50% of the time. And outside that circle the other 50%.

In other words, you can't really target a "building-size" target with these (with maybe exceptions like the Pentagon).

For nuclear payloads, a few hundred meters of error is much less of an issue, of course.

In the first Iraq war, "surgical strike" was euphemism for undiscriminate carpet bombing. Was the second Iraq war any different ?

In a world without nukes, we would've been all about precision targeted ICBM munitions. In a war they would've been used to hit government centers, military bases, staging and supply areas, oil refineries and wells etc.

It's an infinite range weapon which arrives in 20 minutes to kill a target your spy satellites see. They would be used all the time.