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boacvc10
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what are typical capabilities of missile propulsion systems -

Fri May 29, 2020 2:39 pm

Wondering.

According to Wikipedia (hey, this is a.net) air-breathing propulsion systems are used for cruise missiles (makes sense, they have to travel a long time). Is loitering allowed before a strike is ordered? BTW, are there any civilian derivatives of those engines/civilian analogs in use in small aircraft?

For the solid propellant propulsion based missiles, are they always on for the whole trajectory, and what happens when it's all gone?
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flyingturtle
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Re: what are typical capabilities of missile propulsion systems -

Fri May 29, 2020 3:44 pm

boacvc10 wrote:
According to Wikipedia (hey, this is a.net) air-breathing propulsion systems are used for cruise missiles


Yes, it goes back to the Bloodhound missile, which entered service in 1958. It used an air-breathing ramjet. The much older German V1 was air-breathing too.

boacvc10 wrote:
Is loitering allowed before a strike is ordered?


One thing to keep in mind is: Loitering gives the enemy more time to detect the missile. Bombers loiter too. Why shouldn't cruise missiles?

boacvc10 wrote:
are there any civilian derivatives of those engines/civilian analogs in use in small aircraft?


A cruise missile engine has to work only once... so, there are different requirements regarding reliability and maintenance. Also, the cruise missile engine probably works in a much tighter envelope, it flies at a constant speed at a constant altitude, while your Cessna has to have very different power-settings (taxiing, climbout, approach...).
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mxaxai
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Re: what are typical capabilities of missile propulsion systems -

Fri May 29, 2020 3:51 pm

Deviations from the direct route, yes (usually pre-planned to circumvent enemy air defence), loitering, no. This may change with future 'expendable UAV'.

Cruise missile engines are usually pretty small, too small for any but the lightest civilian aircraft. Remember that cruise missiles usually weigh only 1000 - 2000 kg, while the lightest jets start at ~2500 kg. I'm not aware of any direct technology transfer to the civilian market. (There were some pretty heavy designs in the first generation of cruise missiles whose engines were shared with contemporary light military jets).

Missiles with solid propellant in general have a short burn phase (several seconds) and an extended glide phase (several minutes). However, cruise missiles with solid rocket boosters often have a second engine with liguid propellant; the booster accelerates the missile to its operating speed & altitude and the liquid engine (turbojet, ramjet) is used for sustained flight.
 
SuperiorPilotMe
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Re: what are typical capabilities of missile propulsion systems -

Fri May 29, 2020 5:21 pm

boacvc10 wrote:

(hey, this is a.net)


You certainly got that right.


Is loitering allowed before a strike is ordered?


The technology to allow that to happen is still relatively extremely new and on top of that based very much on operational context. It's not a limitation of propulsion but a limitation of software and computing power, and while it's certainly theoretical to have nuclear cruise missiles be capable of loitering (indeed, I very vaguely recall rumors of AGM-86 and SRAM having this capability) it's at best not politically desirable to admit you have this capability and at worst an outright treaty violation. It's tantamount to saying you're ready to nuke your enemy at a given notice - granted this was exactly how the Cold War was fought anyway but there's a significant difference between missiles in silos and bombers on alert or even in orbits as opposed to having cruise missiles specifically designed not to be recovered doing those same orbits. The same concerns exist even for conventionally-armed cruise missiles like JSOW.

However there are specific anti-radar missiles designed to have this capability specifically to aid in hunting radars. That's about the extent international treaty and really good taste will allow (although if Putin, Trump and Xi politically survive COVID-19 good taste may very well not).

BTW, are there any civilian derivatives of those engines/civilian analogs in use in small aircraft?


Yes. The J85 used on the F-5/T-38 and first generation bizjets was originally designed for large cruise missiles. Some shared technology from microfans for modern cruise missiles has been applied to some VLJs.

For the solid propellant propulsion based missiles, are they always on for the whole trajectory, and what happens when it's all gone?


I don't know what you mean by "whole trajectory." Some missiles are designed to have powered-down diving portions (Russian Klub). Any unexpended propellant would typically spray and catch afire when hitting the target which, considering that target destruction is the whole point, is considered highly desirable but not necessarily a specific design goal.
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rfields5421
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Re: what are typical capabilities of missile propulsion systems -

Fri May 29, 2020 10:53 pm

boacvc10 wrote:
Is loitering allowed before a strike is ordered?


You are thinking UAVs, not missiles. While in some respects they might seem similar, they are completely different in design and concept.

UAVs are planned, hopefully, to return to base and be used again. They carry a weapon/ munition that is to be dropped/ launched at a target. They are actively piloted, though do have autopilot capabilities in some models. Even FMC type routing for the autopilot.

Missiles, to date, are launch and forget items. They carry a warhead and are planned to be destroyed when the warhead detonates. Some, but not all, do have an inflight abort option.

The possibilities to mix some of the technologies offers interesting possibilities. As noted above - speed and minimal time enroute and on final approach to target are important for missiles in most mission plans.

Flexibility is the priority of the UAV mission plan.
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SuperiorPilotMe
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Re: what are typical capabilities of missile propulsion systems -

Fri May 29, 2020 11:30 pm

rfields5421 wrote:

UAVs are planned, hopefully, to return to base and be used again. They carry a weapon/ munition that is to be dropped/ launched at a target. They are actively piloted, though do have autopilot capabilities in some models. Even FMC type routing for the autopilot.

Missiles, to date, are launch and forget items. They carry a warhead and are planned to be destroyed when the warhead detonates. Some, but not all, do have an inflight abort option.

The possibilities to mix some of the technologies offers interesting possibilities. As noted above - speed and minimal time enroute and on final approach to target are important for missiles in most mission plans.


There are loitering munitions in service, although the lines between loitering munition/missile/cruise missile and "kamikazie" UAV are very much blurred and often arbitrary. It's no longer a technological limitation as it is a political one.

There are major political ramifications to a munition that can loiter to wait to attack targets, especially when it comes to strategic munitions (both nuclear and conventional - and yes there's such a thing as conventional strategic munitions, XGM-109 Tomahawk and AGM-154 JSOW are strong examples). Therefore the most "acceptable" kinds of loitering munitions are the type of munitions designed specifically to attack "popup" tactical targets - namely hostile radars, armor, or even those of a vaguely defined terrorist nature (the lattermost tends to be what separates loitering kamikazie UAVs from loitering missiles and munitions - the ability to positively identify a target as a terrorist asset, usually with a "man in the loop", as opposed to recognizing and homing on on a broad radar emissions or armor signature).
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DigitalSea
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Re: what are typical capabilities of missile propulsion systems -

Sat May 30, 2020 7:50 pm

SuperiorPilotMe wrote:
[There are loitering munitions in service, although the lines between loitering munition/missile/cruise missile and "kamikazie" UAV are very much blurred and often arbitrary. It's no longer a technological limitation as it is a political one.

There are major political ramifications to a munition that can loiter to wait to attack targets, especially when it comes to strategic munitions (both nuclear and conventional - and yes there's such a thing as conventional strategic munitions, XGM-109 Tomahawk and AGM-154 JSOW are strong examples). Therefore the most "acceptable" kinds of loitering munitions are the type of munitions designed specifically to attack "popup" tactical targets - namely hostile radars, armor, or even those of a vaguely defined terrorist nature (the lattermost tends to be what separates loitering kamikazie UAVs from loitering missiles and munitions - the ability to positively identify a target as a terrorist asset, usually with a "man in the loop", as opposed to recognizing and homing on on a broad radar emissions or armor signature).


The Israeli Harpy & Delilah are good examples of that.
 
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Tugger
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Re: what are typical capabilities of missile propulsion systems -

Sat May 30, 2020 10:01 pm

....loitering.... as a matter of fact the Russian 9M730 Burevestnik being developed is intended specifically to be a "loitering" cruise missile. One option for a nuclear powered cruise missile is that it can fly for an indefinite amount of time (all the while spewing radioactive exhaust). And so when hostilities break out a missile could be launched and fly a loitering pattern over the oceans, for years even in theory (all the while spewing radioactive exhaust), and then be brought back to task once a "final solution" is needed.

Tugg
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SuperiorPilotMe
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Re: what are typical capabilities of missile propulsion systems -

Sun May 31, 2020 12:33 am

DigialSea wrote:
blah blah blah


I can't see what you actually wrote because I have you blocked, but I'm sure whatever it was, it was profoundly stupid, the reason why I have you blocked in the first place.

Tugger wrote:
....loitering.... as a matter of fact the Russian 9M730 Burevestnik being developed is intended specifically to be a "loitering" cruise missile. One option for a nuclear powered cruise missile is that it can fly for an indefinite amount of time (all the while spewing radioactive exhaust). And so when hostilities break out a missile could be launched and fly a loitering pattern over the oceans, for years even in theory (all the while spewing radioactive exhaust), and then be brought back to task once a "final solution" is needed.


Yes. And 9M730 Burevestnik is very much a treaty-busting weapon. If anything it almost seems as if literally every single design aspect and goal of this weapon is to see how many international treaties it can bust in the first place.
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