Why aren't pulsejet cruise missiles a thing?

Only thing with a worse SFC would be a subsonic ramjet which is like an afterburner without the "before".

Oh. And, what part of the pulsejet do you hook up the the generator/alternator driveshaft to?
 
Pulsejet missiles arent necessarily dumb. Maybe if NATO resurrected them around the 1980s as a cheaper standoff system they'd be widely employed. But not in the age of advanced energy storage techniques and electric propulsion.

However cheap a pulsejet can be, I'd always bet on a 3D-printed, electrically powered propeller to beat it in any price comparision.
 
3d printing isn't cheap and electric propulsion offers not more range than a pulse jet. As said, pulse jets produce thrust at zero speed, so they could take off from a runway, but a truck with an electric linear motor catapult might be the better alternative.
 
Nicknick said:
3d printing isn't cheap
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Yeah, and programs like Replicator and chinese sorceries are looking at dramatically improving additive manufacturing tech to greater efficiency, scalability and cost reduction practices.

And this is the first time I've ever heard anybody saying 3D printing isn't cheap.
Nicknick said:
and electric propulsion offers not more range than a pulse jet.
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The prime benefit is cost. Electricity is alot more accessible than fossil fuel. Batteries can directly power electronics so the smart bits aboard a drone dont need their own power storages, which free up alot of space.
 
If you know where to print metal for cheap, please tell me!

The price of the fuel in a suisidal drone really doesn't matter at all... A simple small batterie is sufficient for the electronics and actuators, we are talking about one hour flight time!
 
Nicknick said:
If you know where to print metal for cheap, please tell me!
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No idea but lord Google told me this:
3D printing materials can vary widely, with options that include plastic, powders, resins, metal and carbon fiber. These materials make 3D printing a promising option for many parts, from highly accurate aerospace and industrial machinery components to customized consumer goods
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Plastic should be cheap, no? We are looking at sub-10k missiles here, any semblance of durability should go out of the window.
And another message from lord Google
Material for drone airframe and other components can be different depending on the cost, payload, and performance. Predominantly plastics are used to construct the frame of regular consumer drones and carbon fiber composites for high-performance drones. Carbon fiber makes the drone more agile, lightweight, and durable.
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If hobbyists can print drones for cheap from plastic, I couldn't see how our junkyard cruise missile here should be any different. And with electrical parts that dont move much ( only the propeller shaft and blade are main sources of vibration, as opposed to the whole pulsejet assembly. And I've seen magnets-based power generator that is static throughout!).
Nicknick said:
we are talking about one hour flight time
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A battery pack to power a drone the size of a V-1 should easily hit that level of endurance imo.
 
asVAL said:
And this is the first time I've ever heard anybody saying 3D printing isn't cheap.
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Allways a question of what you print. But yeah for most Things its relativ cheap but getting good machines isn't cheap either.
 
asVAL said:
No idea but lord Google told me this:
Plastic should be cheap, no? We are looking at sub-10k missiles here, any semblance of durability should go out of the window.
And another message from lord Google
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Allways a question of requierments. Tought for something like a V1 there could be Problems without modifications as it was never designed with sutch materials (which can go in both ways good or bad).
 
Printing metal is very expensive because you need a lot of laser energy and expensives powders. It also works best with non oxidizing metals, which tend to be more expensive than ordinary steel or Aluminum.

It is only cheap for small batch production, but not for mass production. You can't find any 3d printed parts in mass produced automobiles.

Battery powerd planes can hardly fly 300 km and even if so, not with the speed of a V1. The hole electric drive train isn't cheap (see the price of electric cars) and will require a lot of expensive materials. So for a disposable mass produced drone, this is only feasable for very small sizes, were material costs are low in absolute numbers and mass produced parts are allready available.
 
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Desertfox said:
GLSBD probably makes a pulsejet cruise missile obsolete.
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As long as the goal is to carry more warhead for a longer range then no. Also the need of an M270 or Himars is limiting just like the whole GPS problem we see in ukraine but this also applies to the pulsjet weapon.
 
kqcke for you said:
the need of an M270 or Himars is limiting
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Not that limiting.

The US has ... many of those (on the order of 1000!), and Poland is working on equaling the numbers of the US Army.

The US also has 25 Battalions of HIMARS, with ~18 trucks per battalion, for roughly 450.

Our Pulse-jet cruise missile requires a dedicated launcher setup at least the same size as HIMARS, if not bigger, and has a much lower rate of fire. HIMARs can drop 6x GLSDB in a few seconds, it'll probably take a couple of minutes to launch each PJCM.



kqcke for you said:
just like the whole GPS problem we see in ukraine but this also applies to the pulsjet weapon.
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Funny, the USAF just dropped a $24mil contract to install Home-on-GPS-Jamming chips into JDAM tailkits and SDBs.
 
Scott Kenny said:
Not that limiting.

The US has ... many of those (on the order of 1000!), and Poland is working on equaling the numbers of the US Army.

The US also has 25 Battalions of HIMARS, with ~18 trucks per battalion, for roughly 450.
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But the rest don't have that many
Scott Kenny said:
Our Pulse-jet cruise missile requires a dedicated launcher setup at least the same size as HIMARS, if not bigger, and has a much lower rate of fire. HIMARs can drop 6x GLSDB in a few seconds, it'll probably take a couple of minutes to launch each PJCM.
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I mean you don't really need mutch except a Launch rail, a rocket motor and your pulsjet if we do it as simple as possible (and effectiv). But yeah it ain't cheap, nor small nor light

Scott Kenny said:
Funny, the USAF just dropped a $24mil contract to install Home-on-GPS-Jamming chips into JDAM tailkits and SDBs.
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I know. Im still hopping for it to go onto GLSDB
 
Aluminium 3D printing can now be done using a cheap extruded filament printer. The filament id metal loaded and then post processed to remove the plastic binder. The strength of the final part is around 99% of billet, so you don't need expensive and energy intensive laser sintering.
Per unit 3D printing will always be more expensive than almost any alternative production method if you 3D print a conventional design. The cost saving only comes when you design for the process and consolidate many parts to slash the assembly or similar fabrication costs.
 
@OliverSedlacek This kind of metal printing is much cheaper than direct laser sintering, but the tolerances are very sluguish and you need a lot of support structure. Once, I wanted to use it for making hollow pistons but I gave up...

Despite beeing cheaper than laser sintering of metal, it is still much more expensive than any mass production technology.

@kqcke for you : As writen by @jabuzzard , an electric linear motor launch rail monted on a truck would be an appropiate launch solution, easy to handle and without much operational effort. Despite that, I don't see a reason why pulse jets would't start from a runway (could be an ordinary street).
 
Nicknick said:
@kqcke for you : As writen by @jabuzzard , an electric linear motor launch rail monted on a truck would be an appropiate launch solution, easy to handle and without much operational effort. Despite that, I don't see a reason why pulse jets would't start from a runway (could be an ordinary street).
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Because a Pulsjet need compressed air which it doesn’t suck in without starting it. So either you got some compressed air on the vehicle or you get it from an outside source like a catapult or rocket motor
 
Nicknick said:
No, the compressed air in the V1 was only used to pump the fuel into the combustion chamber (instead of using a pump) and to drive the control mechanism. The Pulse jet was started by spark ignition and it ran before it was beeing catapulted:

View: https://www.youtube.com/watch?v=WyidSlJzfmo&ab_channel=radiorolli
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Well your right after looking into it again but it wont work allways as you need to be able to create the compressed air onboard because of the valves but that only works for the valved ones. The efficiency is also Bad compared to just shooting some compressed air into it.
 
Well, it did work for the entire duration of the flight, but I believe no one would use compressed air for flight control anymore. We've gone a long way in automatic controling, navigating and steering since than...

It might habe been, that some small amount of compressed air was also used to create a fuel/air mixture for the first bang (not mentioned in the video), however, any truck in the world allready has a compressor and a compressed air system and could provide that with ease.
 
Or a small cartridge should do the trick for some just to get enough speed for self-sufficiency.
 
kqcke for you said:
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.

Maybe.

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.
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You have fallen into the classic trap. Ukraine is using noise to get a general tracking of the incoming missiles. But it can already detect Shahed and Kalibar missiles so unless you have some whisper quiet engine system worrying about the noise is pointless. Have you seen the videos of Storm Shadow missiles on YouTube? it is not quiet either. So noise is not important because nothing is quiet enough not to be detected, sound is too slow to be used for targeting and nobody is going to complain about your pulse jet-powered cruise missile making too much noise in a war zone. I am pretty sure that you could one reduce the noise by cutting the tail of the pulse jet with chevrons like the Boeing 787 engine cowlings. Two have it fly a none direct route, zig-zag etc. to throw off any tracking.

As for size yes it's big, but a Storm Shadow missile is big, it's 5.1m long which is not exactly small. Yes the V1 was bigger, but a modern replacement could be smaller because the V1 used wire-wrapped tanks with compressed air to power the thing. The energy density of which really sucks compared to an alkaline battery. Ordering 100k electric fuel pumps from the likes of Bosch is just noise in the system and a few extra million D cells are also noise in the system. That would allow you to make it significantly smaller.
 
Pretty sure the compressed gas in the V1 was to pressurise the fuel and get it to flow into the jet. Bulkier than a battery and a pump but super simple and reliable. The other thing about the V1 is that the size of the jet is pretty small compared to the size of the charge, so all in all it was a pretty efficient design.
 
Desertfox said:
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.
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It only needs to last ~30 minutes maximum. You just pot the entire thing and mount it on vibration mounts. It's cheap you are not going to do repairs on it, it won't be a problem. There is no point in making something more expensive to achieve a 99% success rate if you can achieve a 90% success rate for a tenth of the price. You need to think Starlink satellites and not GPS satellites.
 
jabuzzard said:
You have fallen into the classic trap. Ukraine is using noise to get a general tracking of the incoming missiles. But it can already detect Shahed and Kalibar missiles so unless you have some whisper quiet engine system worrying about the noise is pointless. Have you seen the videos of Storm Shadow missiles on YouTube? it is not quiet either. So noise is not important because nothing is quiet enough not to be detected, sound is too slow to be used for targeting and nobody is going to complain about your pulse jet-powered cruise missile making too much noise in a war zone. I am pretty sure that you could one reduce the noise by cutting the tail of the pulse jet with chevrons like the Boeing 787 engine cowlings. Two have it fly a none direct route, zig-zag etc. to throw off any tracking.
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The thing is most pulsjets and propeller are just slow which makes this effectiv to shoot down(even if its only used for the more slower drones with handguns). Compared to Kalibr or storm shadow which just go mutch mutch faster ~2-4 the speed of the smaller drones. Pulsjets may sit inbetween given the design of it.
jabuzzard said:
As for size yes it's big, but a Storm Shadow missile is big, it's 5.1m long which is not exactly small.
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Still mutch shorter than the 8.32m of V1
jabuzzard said:
Yes the V1 was bigger, but a modern replacement could be smaller because the V1 used wire-wrapped tanks with compressed air to power the thing.
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At that point one could build a mutch more optimised design given the needed capabilitys.

For that matter the X-Jet (and cruise missile) design from Bruce Simpsons is the closest thing we may see to this. But the data he published showed a quite good engine with a amazing SPFC of around 1.2ish.

Edit: Link to his Website: https://www.aardvark.co.nz/pjet/xjet.shtml
 
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