Why aren't pulsejet cruise missiles a thing?

ram jets need supersonic speeds to produce any reasonalble power (Lorin types work sumbsonic, but are very unefficient) and produce zero thrust with no/low speeds. You can surly built cheap ram jets, but I doubt that you could built cheap supersonic drones for controled flight.

Puls jets could also be started from a runway, they produce significant thrust at zero speed.
 
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It's unclear that that's true. A cheap pulsejet drone would have longer range than an equivalent cheap solid rocket missile... but without a fairly complex control system, those drones are going to be all over the place at long range. One virtue of being relatively short ranged is that rocket missiles can saturate a target such as a city.
Of course, that cheap pulsejet drone would likely need a solid rocket booster to launch it, at least from the ground, a helicopter, a ship, or a boat.
 
Of course, that cheap pulsejet drone would likely need a solid rocket booster to launch it, at least from the ground, a helicopter, a ship, or a boat.
Yes. which means you already have to build a fairly substantial solid rocket. Why not make it a bit bigger and put a warhead on it?
 
I don't agree, a pulse jet drone could start from a runway just like the Saheed drones, it produces thrust at zero speed.

There are tactical reasons for not using runways but its not impossible.
 
I could see one as a drone carrier.

Drones don't have much legs.

Usually, the bigger aircraft releases smaller weapons....this may invert things. The drones have good avionics...and tell it's pulse-jet ride what to hit?
 
The reason you don't see pulsejet cruise missiles is that historically it didn't make economic sense to deal with the limitations of pulsejets given the cost of the guidance system required to achieve the CEP desired. Earlier in this thread there are suggestions that the guidance for a Shahed drone might be as much as half the £16k cost. The reality is that using commercial off the shelf components it should cost no more than £1k at the very outside, more like half that.

So let's compare the German V1 to a Storm Shadow. The later F1 variant of the V1 had a ~500kg warhead and a range of 250 miles which is comparable with the Storm Shadow. Noting the Shahed 136 has only a ~50kg warhead. There are improvements you could make to a modern V1 variant that could easily push the range out to 300+ miles. Mostly make it out of lighter materials and improve the aerodynamics, though even the Germans were developing an improved Argus As 014.

The attraction of a pulse jet is always the price. The V1 cost the equivalent of about £20k to make in today's money, whereas the cost of a Storm Shadow is more like £2 million. The guidance system so; laser ring gyroscope INS, jam resistant GNSS and terrain contour mapping with IR terminal guidance will be mid six figures alone. At that point, a cheap pulse jet power plant is not worth the compromises. That <10m CEP of the Storm Shadow is worth all the extra cost compared to the 11km CEP of the V1.

However it is now 2024 and well we could use a MEMS INS, several commercial off the shelf GNSS receivers and frankly a Raspberry Pi equivalent with a Sony global shutter and a digital visual positioning system, and similarly for terminal guidance. All for under £1k unit cost to achieve a similar CEP. Even 10 years ago these technologies were not viable. The idea you could have 500GB of high resolution satellite photography on a £50 micoSD card for the visual positioning system was fantasy land.

Now it starts to look a lot more attractive. For every Storm Shadow missile, you could have 100 modern V1 variants with a similar range and payload. These days it would be entirely feasible to use an electromagnetic launch system mounted on a 8x8 military vehicle instead of the static steam catapults the Germans used. Just park the launcher pointing roughly in the right direction and it can course correct after launch to get on target. It is now common place for rollercoasters to use electromagnetic systems to accelerate the rides to over 100mph which is in the ball park for launching a V1 variant.

Putting this into context imagine you had £4 billion. Spent £1 billion developing the system, £2 billion buying new V1 variant flying bombs, and the remaining £1 billion on launch and support vehicles at say £15 million per launcher. That gets you 100,000 missiles and 67 launchers. Imagine for a moment this is in Ukraine that would be 274 missiles a day every day being launched at anything within say 250 miles of the front line. You could have 100 bombs a day landing on Sevastopol harbour for a year, 100 bombs a day landing on the Kerch Bridge for a year and still have another 70 missiles a day for other targets every day for a year. If you are willing to drive closer to the border you could rain down bombs on Moscow as it is less than 300 miles from the Ukrainian border.

There are other things about this. If you are making 100,000 of these then modern high volume manufacturing methods could be employed that simply were not available to the Germans. So for example it would be entirely feasible to make the body and wings out of diecast aluminium that simply snaps together. Injection moulded plastic nose cones that snap on. Some of this feeds back into the improvements to the bomb. Elliptical wings have low induced drag great for increasing range but difficult to manufacture. Not a problem when the wing is a handful of clip together diecast aluminium segments. Before anyone says you can't do that I suggest checking out what Tesla is doing with manufacturing car bodies out of large diecast aluminium segments. These modern high volume manufacturing methods also help to keep the unit cost as low as possible.

How about an airburst version that sprays 10mm steel ball bearings everywhere? Ok not as good as tungsten but good enough to make a right mess of an airframe. Because we have so many it would be feasible to program them to cover the entire airfield by having them go off in a grid pattern. The possibilities are really quite extensive.

So again why has nobody taken this up? Well firstly this has only been a viable option in the last two or three years and it will take time for people to wake up to the changes that make this sort of weapons system possible. The other issue is that prior to the Russian invasion of Ukraine, the sort of high-intensity conflict where you would want 100,000 flying bombs a year didn't exist. When someone wakes up and develops one well that will be very scary. For context, the UK has pledged £7.1 billion in military aid so more than enough for 100 launchers and 200,000 flying bombs. The biggest problem would be sourcing 100,000 tonnes of high explosives for 200,000 flying bombs.
 
@jabuzzard : Well analysed, however, I find the idea of mass produced "V1.20" quite fearsome. This would again lead to mass destruction of civil buildings and infrastructure like in WW2. No doubt, it would fit into the Ukraine war very well but I hope anti drone technology will prevent this in future.

I do agree, that such pulse jet drones could be cheap, but not with the purchasing process of many Nato members, especially Germany...
 
So again why has nobody taken this up? Well firstly this has only been a viable option in the last two or three years and it will take time for people to wake up to the changes that make this sort of weapons system possible. The other issue is that prior to the Russian invasion of Ukraine, the sort of high-intensity conflict where you would want 100,000 flying bombs a year didn't exist. When someone wakes up and develops one well that will be very scary. For context, the UK has pledged £7.1 billion in military aid so more than enough for 100 launchers and 200,000 flying bombs. The biggest problem would be sourcing 100,000 tonnes of high explosives for 200,000 flying bombs.
Which means it'll be at least a decade away, maybe longer if someone in government is going to insist that the chipset be hardened etc.

Basic governmental contracting is 10 years from idea to IOC. Minimum.
 
As said, this way of thinking is typicall for the NATO, but the Ukraine prooves, that cheap and hardly tested weapon systems can do the job as well.
 
You need planes for glide bombs, so a mass attac with many glide bombs at the same time to overwhelm the defence systems is impossible. It is also a drawaback, that the planes must get close to the front.

A range of 100 km is much shorter than the 370 km max range of the V1, so it is not comparable at all.
 
You need planes for glide bombs, so a mass attac with many glide bombs at the same time to overwhelm the defence systems is impossible. It is also a drawaback, that the planes must get close to the front.
B2 with 90something SDBs in one bay says hi.
 
Basically the glide bombs took over the niche of pulsejet missiles. Modern glide bomb kits allow 75-100 km range - which is pretty comparable with the pulsejet missile effective range with the same warhead weight. And glide bombs are significantly cheaper.
IMO 75-100km range for a glide bomb doesn't make it a competitor to a V1.X which would do 400km for sure. As per jabuzzard's excellent analysis, this looks do-able and cost effective and very scary. As for timescales, the Ukrainians for sure would not be looking at a 10 year development plan and could go for a commercial built it-break it-fix it cycle.
 
B2 with 90something SDBs in one bay says hi.
Operating such a hughe bomber close to the front might be dangerous. To my knowledge the Russians aren't using their largest bombers for the glide bombs.

Despite that, we will see, it might become a future option to use large bombers for swarms of glide bombs (I hope not...)
 
That’s exactly the problem, the planes will be endangered when flying over enemy territory. Operating planes will also cost much more than operating trucks for the pulse jets, which can fulfil their role in the hinterland.
 
Operating such a hughe bomber close to the front might be dangerous. To my knowledge the Russians aren't using their largest bombers for the glide bombs.

Despite that, we will see, it might become a future option to use large bombers for swarms of glide bombs (I hope not...)
Not sure about "large bombers", but B21s will definitely get used for that. Which means at least 90something SDBs, and probably more since the B21 bay is longer than the B2 bays are. My personal suspicion is that the B21 has the same size bay as the B52, which technically can hold about 50% more than a B2 bay (8x SRAM plus 4x B61 nukes, for example).

I'm kinda expecting the USAF to push for an F111-to-B58-class fast VLO bomber to replace the F15Es, and for mental simplicity it's got a bomb bay 6ft wide and 28ft long, same size as a B52 (and I suspect same size as B21). Internal bombload of 24klbs, maybe 30k if you pull the rotary launcher out for a GBU-57 MOP.

The Strike Eagles are fairly rapidly running out of service life. Assuming 16k hours total after a major overhaul at 8k and service from 1990 at 330hrs/year flight time, the Strike Eagles would have had to go into their major overhauls at about 2014 and will be completely out of service life at 2038. Needs at least 10 years development time from concept to first flight, so the USAF is coming up on the latest they can make a decision. Okay, yes they could just order another 200x B21s to replace the Strike Eagles 1:1 ish, but that's got several times the range of a Strike Eagle and is just flat too much airplane for the mission. Assuming that the B21 has the same range as a B2 as a minimum, that's 6000nmi. The Strike Eagle Replacement is probably only going to have a ~2000nmi range at full load.
 
Lets not forgett, that many countries (or terrorists) could built simple pulse jet drones, but not something like the B21
 
Lets not forgett, that many countries (or terrorists) could built simple pulse jet drones, but not something like the B21
Yeah, I'm much more bothered by the fact that you can make a cheap and stupid-accurate guidance system these days... drops the floor for terrorists to raise hell.
 
We schouldn't end up with a design challange for the best terrorist attac drone....
 
Pulsjet are kinda freaky. While they have high potenial many don't see the worth as those countries often have a good enough way for turbojets which do the job just find, aren't as large as a aircraft carrier and can be more quieter which of course is important for civil aerospace. When they get small enough they are a good competition but i don't know how far they are with that.
 
Pulsjet are kinda freaky. While they have high potenial many don't see the worth as those countries often have a good enough way for turbojets which do the job just find, aren't as large as a aircraft carrier and can be more quieter which of course is important for civil aerospace. When they get small enough they are a good competition but i don't know how far they are with that.
A cheap turbojet to fly a ~500kg payload cruise missile would cost more than a modern updated V1 would cost in total and noise is irrelevant in a war zone. Of course, a modern V1 would fly like a Storm Shadow at ~30m height terrain following with popup attack. I am quite sure that a BROACH style warhead is doable cheaply. At the end of the day it's just a shaped charged primary to blast a hole in the target so the main payload can penetrate the target and explode later. Shaped charges are not exactly rocket science, just a cone of copper surrounded by explosives. You can diecast copper so mass production should not be a problem. Though I imagine the Storm Shadow missile has an array of them at the front to make a big enough hole.
 
I'm pretty sure the Shahed meets that.
Not really they are kind of junk, only a 50kg warhead and need rocket assistance to launch. All they have going for them is their range. You can get them from Iran to Israel which is I am 100% sure was their design criteria.
 
A cheap turbojet to fly a ~500kg payload cruise missile would cost more than a modern updated V1 would cost in total and noise is irrelevant in a war zone.
Don't think so given V1s size. Noise also isn't irrelevant as it can be used to detect it. Ukraine already does it and using an pulse Jet probaly makes it easier.
Of course, a modern V1 would fly like a Storm Shadow at ~30m height terrain following with popup attack. I am quite sure that a BROACH style warhead is doable cheaply.
Maybe.
At the end of the day it's just a shaped charged primary to blast a hole in the target so the main payload can penetrate the target and explode later. Shaped charges are not exactly rocket science, just a cone of copper surrounded by explosives. You can diecast copper so mass production should not be a problem. Though I imagine the Storm Shadow missile has an array of them at the front to make a big enough hole.
Again it doesn't change the fact that its big and bulky which isn't ideal for many applications who aren't in need for everything they can get.

Its not impossible but often there more requierments given for many things. Allways a question of requierments and atleast for now they wont replace turbojets and -fans but for they have very big possible applications.
 
The biggest issue with pulsejets is vibration. Vibration will kill electronics fast, and until that's solved you can't really strap an inexpensive guidance system into one.
 
Not really they are kind of junk, only a 50kg warhead and need rocket assistance to launch. All they have going for them is their range. You can get them from Iran to Israel which is I am 100% sure was their design criteria.
Point granted about the small warhead, but pulsejets need a catapult or rockets to launch, too.
 
And after i looked into some details for Pulsjet i found some specifics from Wave Engine Corp. with there J1-1 engine. Based on its data it is already outperformed in every aspect with a PBS TJ40-G1/G1 INS/G2.
SPFC: TJ40: 1.442 lb/lbf/hr J1: 2lb/lbf/hr
Trust: TJ40: 89-96Ibf J1: 55Ibf
Weight: 7.5 -8.3Ib J1: 18Ib
Size: TJ40: 5.79 in x 5.79 in x 11.97 in
J1:5.5 in x 12.5 in x 64 in

(Also TJ40 produces some +150W of energy atleast too.)

Now this comparison gives ous atleast a look at it which indicates that modern Microturbojets are just so mutch better except for the price.

Edit: Lets wait and see how there K1 will work better as that is a scaled up version.
Also using 2 J1 next to each other would make it large enough for a TJ100, TJ100P or TJ150 could be used which produce trust at 269 - 337 Ibf and have an SPFC of around ~1.1lb/lbf/hr.
 
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