"Burevestnik" Nuclear-powered cruise missile

Burevestnik is likely a nuclear thermal ramjet engine. Its a nuclear reactor where the core has conduits through it so that gases can be driven through to be heated up and expelled from the rear. The reactor doesn't produce any appreciable radiation until the control rods are withdrawn, so shielding isn't needed when the weapon is in storage or being handled, though they may use a lead-lined "apron" for ground handling to protect personnel from cumulative radiation, a bit like an X-ray technician.

Its likely to be a ramjet design for simplicity, so relies on rocket booster to achieve sufficient speed to "ignite" the engine, ie where it generates sufficient thrust to maintain forward flight. There is no water (or liquid metal) coolant - the air being rammed through the engine removes heat and limits temperature increase in the core. It would need some impressively fast control loops to modulate the control rod position with airflow and core temperature. If the airflow stops and the rods aren't inserted sufficiently or rapidly enough, a core meltdown is entirely possible.

While the missile in flight will emit radiation, its unlikely to leave a "radiation trail", that's mostly Hollywood hype. Radiation to environment would have two sources (1) fuel particles escaping, which we can rule out as the reactor will be sealed, and (2) nucleo-genesis where fission products (such as fast neutrons) strike the nuclei of atmospheric gas and transmute it into an unstable radioactive element which subsequently decays in the environment. Unlike solid materials like steel and concrete which contain heavy elements prone to feeding the nucleo-genesis process, air is composed of light stable molecules and doesn't get radioactive by prolonged exposure to stray radiation.

wow interesting stuff, thx

@Big_Gazza:

Thanks! What would be in your opinion the main technological problem for developing such reactor? It does not seem overly complicated and the benefits are obvious so one would expect to see its use widespread.

LMFS wrote:@Big_Gazza:

Thanks! What would be in your opinion the main technological problem for developing such reactor? It does not seem overly complicated and the benefits are obvious so one would expect to see its use widespread.

Widespread usage for what?

What usage can you imagine a thermal nuclear ramjet reactor ,apparat to deliver doomsday weapons?

And even for that the ICBM more cost effective, with MIRV.

Singular_Transform wrote:

What usage can you imagine a thermal nuclear ramjet reactor ,apparat to deliver doomsday weapons?

Burevestnik, isnt this  thread about it?

And even for that the ICBM more cost effective, with MIRV.

of course not, otherwise it would have not been introduced at first place. But it was

LMFS wrote:@Big_Gazza:

Thanks! What would be in your opinion the main technological problem for developing such reactor? It does not seem overly complicated and the benefits are obvious so one would expect to see its use widespread.

One difficulty is in designing a reactor power control system that is sufficiently fast and reliable under all operating conditions to allow it to run at a very high core temperature, yet safeguard it against an inadvertent over-temperatures caused by any disturbances in the cooling air flow.  The system must be bullet-proof so that you do not get (a) missiles flaming out because of inadequate power, or (b) inflight meltdowns with could result in crashes (best case) or loss of reactor containment (fancy way of saying explosion...) and airborne spreading of high-level fuel materials (worse case).

You'd also need to design a resilient and reliable control system to run the engine, and operating (motorised) mechanisms needed to run reliably for both air flow control (via a variable orifice or venturi of some kind) and core control rod insertion control.  Mechanism need to be fast acting, reliable, resilient to wear, and potentially comprised of materials that are resistant to neutron damage.  Weight is a premium, so you can't have massive shielding or robust environmental containment like you do with a normal reactor, and the engine is compact so you can't locate the essential moving parts away from the hot zone. Electronics need to be rad-hardened and employ high levels of redundancy to ensure they can continue to operate during the duration of the flight, and you need some fancy software to control trajectory and decide when to make the final attack run (as the bird needs to be fire-and-forget).  You'd need to rely on inertial guidance as a baseline, but with position updated when possible using Glonass/Beidou or HATOstani GPS systems (though no GPS-type guidance can be relied on in an all-out strategic exchange scenario), or possibly star-trackers - not a new problem in this age of near-intercontinental range CMs, but the duration of flights is very long, and without the occasional precise position update, navigational errors in inertial systems will accumulate and accuracy on target becomes impossible.  Finally, I imagine you would want to have some kind of recall-capability or "kill switch" that would allow you to shutdown a bird in event of a false launch, but to include adequate safeguards against "hacking" attacks by enemy counter-measures.

It sounds conceptually simple (build a modern nuke version of the old Nazi buzz-bomb) but as always the devil is in the details...

GunshipDemocracy wrote:

Singular_Transform wrote:

What usage can you imagine a thermal nuclear ramjet reactor ,apparat to deliver doomsday weapons?

Burevestnik, isnt this  thread about it?

I just can repeat my question, what else usage can you imagine for this reactor ,apart from being the delivery vehicle of a doomsday bomb?

GunshipDemocracy wrote:

And even for that the ICBM more cost effective, with MIRV.

of course not, otherwise it would have not been introduced at first place. But it was

The START and the cancelled ABM treaty together decreased the freedom of movement for Russia.

If there is no START then they just increase the number of missiles, but in this environment they need new delivery mechanisms.

Singular_Transform wrote:

GunshipDemocracy wrote:

Singular_Transform wrote:

What usage can you imagine a thermal nuclear ramjet reactor ,apparat to deliver doomsday weapons?

Burevestnik, isnt this  thread about it?

I just can repeat my question, what else usage can you imagine for this reactor ,apart from being the delivery vehicle of a doomsday bomb?

this exact type or something alike? this exact type only here,similar can be used in space tugs for exmaple

GunshipDemocracy wrote:

And even for that the ICBM more cost effective, with MIRV.

of course not, otherwise it would have not been introduced at first place. But it was

The START  and the cancelled ABM treaty together decreased the freedom of movement for Russia.

If there is no START then they just increase the number of missiles, but in this environment they need new delivery mechanisms. [/quote]

It is other way around. START is expiring soon. It's enough not extend it. This is more expensive option though, both procurement and maintenance. Much better cost/effect has Burevestnik. It isnot only cost of creation. This is also cost of US funds invested in building/maintenance of AAD against such threats.

Big_Gazza wrote:

One difficulty is in designing a reactor power control system that is sufficiently fast and reliable under all operating conditions to allow it to run at a very high core temperature, yet safeguard it against an inadvertent over-temperatures caused by any disturbances in the cooling air flow.  The system must be bullet-proof so that you do not get (a) missiles flaming out because of inadequate power, or (b) inflight meltdowns with could result in crashes (best case) or loss of reactor containment (fancy way of saying explosion...) and airborne spreading of high-level fuel materials (worse case).

You'd also need to design a resilient and reliable control system to run the engine, and operating (motorised) mechanisms needed to run reliably for both air flow control (via a variable orifice or venturi of some kind) and core control rod insertion control.  Mechanism need to be fast acting, reliable, resilient to wear, and potentially comprised of materials that are resistant to neutron damage.  Weight is a premium, so you can't have massive shielding or robust environmental containment like you do with a normal reactor, and the engine is compact so you can't locate the essential moving parts away from the hot zone. Electronics need to be rad-hardened and employ high levels of redundancy to ensure they can continue to operate during the duration of the flight, and you need some fancy software to control trajectory and decide when to make the final attack run (as the bird needs to be fire-and-forget).  You'd need to rely on inertial guidance as a baseline, but with position updated when possible using Glonass/Beidou or HATOstani GPS systems (though no GPS-type guidance can be relied on in an all-out strategic exchange scenario), or possibly star-trackers - not a new problem in this age of near-intercontinental range CMs, but the duration of flights is very long, and without the occasional precise position update, navigational errors in inertial systems will accumulate and accuracy on target becomes impossible.  Finally, I imagine you would want to have some kind of recall-capability or "kill switch" that would allow you to shutdown a bird in event of a false launch, but to include adequate safeguards against "hacking" attacks by enemy counter-measures.

It sounds conceptually simple (build a modern nuke version of the old Nazi buzz-bomb) but as always the devil is in the details...

Very interesting Big_Gazza

Being a weapon I guess they can relax some safety features but it is clear than getting it working reliably in all the relevant failure scenarios for a completely new technology surely needs many years of testing and refinement. Apparently the breakthrough in this and the Poseidon reactors was one key feature you mention, that is the capacity to control and throttle the reactor stably and very fast (few seconds from what was mentioned). I wonder what is the limit of the reactor in terms of power. It would be indeed very beneficial if it could accelerate the missile to supersonic flight in the last approach to the target, the nose design doesn't look incompatible with this

what water temp would you need then? 2500k?! earth crust pressure? meh risky - damage of installation. this small reactor used helium for a reason I guess. Anyway with 2000-3000kelvin you would see definitely see flames in nozzle.

That is what makes these reactors so dangerous... the water temperature is hundreds of degrees C but is under enormous pressure, so it is designed to turn into steam while still under high pressure... if there is a leak the temperature can actually mean the steam separates from hydrogen and oxygen... which explodes obviously...

For a ramjet engine you need the "coolant" to get very very hot... so ceramic pipes with liquid metal coolant heated to several thousand degrees by the reactor... air flows through the ceramic pipes, which superheats the air which forces it out the back of the engine moving faster than it came in.... = thrust... the slightly cooled liquid metal coolant goes back through the reactor to get reheated in a constant flow, to maintain heat in the engine...

the question is can it be detected in real time by sensors? radiation.

IR should be visible...

Thanks! What would be in your opinion the main technological problem for developing such reactor? It does not seem overly complicated and the benefits are obvious so one would expect to see its use widespread.

They were working on such engines in the 1950s as huge cruise missile alternatives to ICBMs....

Russia is working on spacecraft using nuclear propulsion now...

[quote]I just can repeat my question, what else usage can you imagine for this reactor ,apart from being the delivery vehicle of a doomsday bomb?[/qutoe]

Delivery system for 1,000 doomsday bombs...

Being a weapon I guess they can relax some safety features but it is clear than getting it working reliably in all the relevant failure scenarios for a completely new technology surely needs many years of testing and refinement.

You should look up the operational history of the Kh-22M... issues with its liquid propellant that had to be loaded just before the aircraft got airborne are interesting....

GarryB wrote:
That is what makes these reactors so dangerous... the water temperature is hundreds of degrees C but is under enormous pressure, so it is designed to turn into steam while still under high pressure... if there is a leak the temperature can actually mean the steam separates from hydrogen and oxygen... which explodes obviously...

thet's wny it unlikely be used this way

For a ramjet engine you need the "coolant" to get very very hot... so ceramic pipes with liquid metal coolant heated to several thousand degrees by the reactor... air flows through the ceramic pipes, which superheats the air which forces it out the back of the engine moving faster than it came in.... = thrust... the slightly cooled liquid metal coolant goes back through the reactor to get reheated in a constant flow, to maintain heat in the engine...

again unlikely liquid metal too.

Very-high-temperature reactor

https://en.wikipedia.org/wiki/Very-high-temperature_reactor

The design takes advantage of the inherent safety characteristics of a helium-cooled, graphite-moderated core with specific design optimizations. The graphite has large thermal inertia and the helium coolant is single phase, inert, and has no reactivity effects. The core is composed of graphite, has a high heat capacity and structural stability even at high temperatures. The fuel is coated uranium-oxycarbide which permits high burn-up (approaching 200 GWd/t) and retains fission products. The high average core-exit temperature of the VHTR (1,000 °C) permits emissions-free production of process heat. Reactor is designed for 60 years of service.[10]

Being a weapon I guess they can relax some safety features but it is clear than getting it working reliably in all the relevant failure scenarios for a completely new technology surely needs many years of testing and refinement.

it is

GunshipDemocracy wrote:

this exact type or something alike? this exact type only here,similar can be used in space tugs for exmaple

Space thug need ion propulsion, that is completely unrelated technology.


It can be last stage of a space rocket, but that needs hydrogen as reaction mass, again, unrelated technology.

GunshipDemocracy wrote:

And even for that the ICBM more cost effective, with MIRV.

of course not, otherwise it would have not been introduced at first place. But it was

The START  and the cancelled ABM treaty together decreased the freedom of movement for Russia.

If there is no START then they just increase the number of missiles, but in this environment they need new delivery mechanisms. [/quote]

It is other way around. START is expiring soon. It's enough not extend it. This is more expensive option though, both procurement and maintenance. Much better cost/effect has Burevestnik. It isnot only cost of creation. This is also cost of US funds invested in building/maintenance of AAD against such threats.


[/quote]

I think the existence of this missile means Russia wants to keep the start.

Singular_Transform wrote:
Space thug need ion propulsion, that is completely unrelated technology.


It can be last stage of a space rocket, but that needs hydrogen as reaction mass, again, unrelated technology.

https://ru.wikipedia.org/wiki/Ядерная_энергодвигательная_установка_мегаваттного_класса

ok unrelated so precisely how reactor in Burevestnik passes energy to missile in different wayif not gas cooling?

I think the existence of this missile means Russia wants to keep the start.

IMHO regardless if Russia wants to keep it (unlikely as US dont want any reductions + never reject ABMs) or not Russia surely wants to keep strategic balance. Since there is more resources on Us side Russia must go innovative, asymmetric way.

GarryB wrote:That is what makes these reactors so dangerous... the water temperature is hundreds of degrees C but is under enormous pressure, so it is designed to turn into steam while still under high pressure... if there is a leak the temperature can actually mean the steam separates from hydrogen and oxygen... which explodes obviously...

Water H2O is thermally stable and will not dissociate into hydrogen and oxygen (and various combinations of the two) in any significant way until temperatures are over 2000 deg C.

GunshipDemocracy wrote:


https://ru.wikipedia.org/wiki/Ядерная_энергодвигательная_установка_мегаваттного_класса

ok unrelated so precisely how reactor in Burevestnik passes energy to missile in different wayif not gas cooling?

Most probably by passing through the reactor core the air.

Singular_Transform wrote:
Most probably by passing through the reactor core the air.

That is my guess too. I cannot see any other way to do it whilst still keeping the missile both 'light', and granting it the mechanical endurance for extended duration cruising.

Singular_Transform wrote:
Most probably by passing through the reactor core the air.

do you mean like air to be directly flowing around core? then what about radioactivity and radiation?

GunshipDemocracy wrote:do you mean  like air to be directly flowing around core? then what about radioactivity and radiation?

Alpha and Beta radiation should be contained by the walls of the core. Gamma irradiation of passing air particles will have little lasting effect since these are light elements with no particularly dangerous isotopes. Trace radionuclides would be formed from dust particles passing through, but the radioactivity level of these will be so widely dispersed in the exhaust and in such minimal quantities (assuming a decent altitude cruising level) that it should be negligible.

The true radiation threat is what occurs when the missile strikes home since containment will ruptured. But as it seems to be intended as a retaliatory strike weapon armed with a fusion warhead, that is something of a mute point.

Teshub wrote:

GunshipDemocracy wrote:do you mean  like air to be directly flowing around core? then what about radioactivity and radiation?

Alpha and Beta radiation should be contained by the walls of the core. Gamma irradiation of passing air particles will have little lasting effect since these are light elements with no particularly dangerous isotopes. Trace radionuclides would be formed from dust particles passing through, but the radioactivity level of these will be so widely dispersed in the exhaust and in such minimal quantities (assuming a decent altitude cruising level) that it should be negligible.

The true radiation threat is what occurs when the missile strikes home since containment will ruptured. But as it seems to be intended as a retaliatory strike weapon armed with a fusion warhead, that is something of a mute point.

There is a failure mode when one or more channels blocked, and the reactor core meltdown and ejected with the gas trail.

There can be many failure mode that releasing reacotr core material to the enviroment.

But at the first few minutes of work there is not enought radioactive material, so it is possible to test the reactor.

The only challange of those reactors is to proove the operational capability of them.

I think there will be a final, few days long flight of a few missile, and afterwards they will launch them only if the launch place is radioactive contaiminated anyway.

thet's wny it unlikely be used this way

PWRs were and are widely used... that is what the explosions they talk about in nuclear reactors are.

Otherwise the nuclear fuel rods would just keep getting hotter and eventually melt and flow downwards in a puddle of self heating liquid... getting hotter and hotter...

they have experimented with liquid metal coolants, but the problem is that if you turn them off and the coolant hardens there is no flow to keep the reactor elements cool, so when you turn it on it overheats and melts down...

again unlikely liquid metal too.

Liquid metal would problematic because you would either need to keep it running all the time to keep the coolant metal in liquid form or it would need to be loaded into the missile in liquid form before use... and would need to continue running all the time to prevent the coolant going hard...

Having said that you could operate a nuclear reactor at the base you store these missiles at and pump the heated coolant into the missiles just before launch... some sort of catapult launch, or more likely solid rocket fuel booster to get it airborne while its reactor heats up to full temperature with the liquid propellent pumped from the rear of the jet engine through to the front in a lattice where the airflow comes through... meaning the heating system is hottest in the rear of the engine and slightly cooler at the front where it would be tapped off to go back through the reactor... which means assuming perhaps a 1.600 degree C heat as it leaves the reactor in the rear of the jet engine to perhaps 1,000-1,200 degrees at the front of the jet engine as it leaves the engine and reenters the reactor.

This base could be located in the middle of nowhere in Russia surrounded by all sorts of air defence systems etc hidden inside an entire mountain range in the Urals... when the missiles are launched they could fly in circles and climb and accelerate to enormous altitudes and then practically head off in any direction... they could take days to reach their targets... even weeks... In fact as long as the facility is hardened and kept secret it could continue to launch missiles repeatedly... monitoring communications and any surviving satellites to find targets worth hitting... a fast neutron breeder reactor could continue to create weapons grade fuel and production should be relatively simple... being a rocket launched ramjet... you don't need turbine blades or any fancy stuff...

Space thug need ion propulsion, that is completely unrelated technology.

High energy gas made energetic by super heating, though in the case of an Ion engine the manipulation with a magnetic field would also boost performance, but I suspect a lot of overlap in technologies...

It can be last stage of a space rocket, but that needs hydrogen as reaction mass, again, unrelated technology.

No reason why a nuclear powered jet engine operating in the atmosphere would need to operate with hydrogen... previously Xenon has been used for Ion engines but it is expensive... I have seen programmes in Russia using Nitrogen... which is super cheap.... 70% of the earths atmosphere is nitrogen and it is inert so there are no storage problems... well liquid nitrogen would be a useful way to store large amounts so there is an issue with very low temperatures.

Ironically a nuclear powered ramjet would be using 70% nitrogen anyway and at higher altitudes the concentration of oxygen is reduced... not that that matters for a nuclear ramjet.

I think the existence of this missile means Russia wants to keep the start.

There is no way of Russia knowing what the US will or will not sign, or will abide by or will rip up and ignore... most of these new systems started development when the ABM treaty was torn up by the Americans.

IMHO regardless if Russia wants to keep it (unlikely as US dont want any reductions + never reject ABMs) or not Russia surely wants to keep strategic balance. Since there is more resources on Us side Russia must go innovative, asymmetric way.

The Americans might want to reduce further, but not include UK and French nukes and also keep their ABM systems (and build a new one with South Korea and Japan), so it might be in Russias interests to let it expire and then use their new breeder reactors to massively increase their stock of nuclear weapons to force the US to the negotiating table with less of a chip on its shoulder and a bit more respect for Russia.

With breeder or fast neutron reactors making fissile material (for fuel and for weapons) becomes much easier and cheaper, so spent fuel rods that would other wise be nuclear waste can be enriched into fuel or weapons grade material...

Water H2O is thermally stable and will not dissociate into hydrogen and oxygen (and various combinations of the two) in any significant way until temperatures are over 2000 deg C.

Perfectly correct, but when under pressure a PWR pressurised water reactor does not operate at 100 degrees C at normal atmospheric pressure... they normally operate at much higher pressures and also much higher temperatures to increase the energy in the steam component... but even then you wont have problems unless there is an issue and you have a meltdown where temperatures get hot enough to melt the uranium fuel rods... at which temperatures any water in the system is a real explosion risk.

Don't try this at home... look up mythbusters and fat fire... where cooking oil is heated to several hundred degrees C... throw water on that and the water instantly converts to steam, spreading the super hot burning oil in a matter state conversion from liquid water to gas steam instantly... very much a form of explosion... which spreads the burning oil in a huge fireball as it spreads the oil into the air where it gets more oxygen and burns more fiercely.

In common sense terms you would expect the water to put out the fire but when transformed into steam its effect is to spread the fuel into the air and add more available oxygen near the fire to the burning oil fuel. The hydrogen and oxygen in the steam don't come in to it, the temperature is not high enough to release them, but a reactor meltdown literally adds fuel in the form of hydrogen gas and oxygen gas and enormous heat... really big boom... with water vapour as the product of the combustion ironically...

There is a failure mode when one or more channels blocked, and the reactor core meltdown and ejected with the gas trail.

There can be many failure mode that releasing reacotr core material to the enviroment.

To be able to turn the engine on and off it would need control rods... rather than dumping cores it would make more sense to deploy control rods to reduce the reaction.

I think there will be a final, few days long flight of a few missile, and afterwards they will launch them only if the launch place is radioactive contaiminated anyway.

Why?

I would say testing it under a wing of the Il-76PP would be enough... they could wrap it in all sorts of containment shields and have probes to measure radiation signatures and other parameters too.

If they can minimise or eliminate the radiation they could develop UAVs for long range patrols around Russia... never leaving Russian airspace... they could test it for years...

Of course no amount of testing can prove something to be infallible....

GarryB wrote:

High energy gas made energetic by super heating, though in the case of an Ion engine the manipulation with a magnetic field would also boost performance, but I suspect a lot of overlap in technologies...

It is connected to the maximum temperature of the core, and the speed of molecules/atoms at that temperature in different gases.
At the possible temperatures of the core (i.e. at highest possible before core meltdown) the hydrogen has 8 km/sec speed.
The xenon based ion propulsion has a speed of 30 km/sec.

GarryB wrote:

No reason why a nuclear powered jet engine operating in the atmosphere would need to operate with hydrogen... previously Xenon has been used for Ion engines but it is expensive... I have seen programmes in Russia using Nitrogen... which is super cheap.... 70% of the earths atmosphere is nitrogen and it is inert so there are no storage problems... well liquid nitrogen would be a useful way to store large amounts so there is an issue with very low temperatures.

Ironically a nuclear powered ramjet would be using 70% nitrogen anyway and at higher altitudes the concentration of oxygen is reduced... not that that matters for a nuclear ramjet.

Nuclear thermal rocket has to use hydrogen, if it using helium ( second best candidate in the periodic table ) then the performance of it will be inferior compared to the chemical rockets.

GarryB wrote:

To be able to turn the engine on and off it would need control rods... rather than dumping cores it would make more sense to deploy control rods to reduce the reaction.

I don't think that the reactor has that much margin to locally shut it down and still operating.

This kind of operation require an oversized ( overweight ) reactor .

GarryB wrote:
Why?

I would say testing it under a wing of the Il-76PP would be enough... they could wrap it in all sorts of containment shields and have probes to measure radiation signatures and other parameters too.

If they can minimise or eliminate the radiation they could develop UAVs for long range patrols around Russia... never leaving Russian airspace... they could test it for years...

Of course no amount of testing can prove something to be infallible....

I don't know.
Maybe they will found a way to test it by other ways to run it in big circle.
Maybe the underwing can work, that better than see a reactor flying rounds above Siberia for days.

It is connected to the maximum temperature of the core, and the speed of molecules/atoms at that temperature in different gases.
At the possible temperatures of the core (i.e. at highest possible before core meltdown) the hydrogen has 8 km/sec speed.
The xenon based ion propulsion has a speed of 30 km/sec.

You are comparing apples with oranges... hydrogen fuel is used (with oxygen) because it is light and accelerates fast in the combustion reaction.

With ion propulsion it is different as it uses magnetism for acceleration... any material can be used... just strip off an electronic and it has an electric charge and can be manipulated easily by magnetic field.

Xenon was chosen because of its very high performance, but nitrogen is orders of magnitude cheaper and much more abundant... it is a bit like airships... hydrogen is cheaper and offers better performance but Helium was safer but expensive.

Old airships used Helium for safety but new airships can use hydrogen fuel cells, and lots of fire retardant technologies to minimise the risk of fire allowing much cheaper operations.

Nuclear thermal rocket has to use hydrogen, if it using helium ( second best candidate in the periodic table ) then the performance of it will be inferior compared to the chemical rockets.

A nuclear ramjet will use the gases the aircraft or missile the ramjet propels is flying through...

I don't think that the reactor has that much margin to locally shut it down and still operating.

I have never heard of any nuclear reactor that "drops cores" except in the Movies like Star Trek.

You need to have the reactor in an inactive state otherwise its engine will always be running... how would you store them?

I would expect in operation when the solid rocket booster engine fires and launches the missile control rods will be raised to expose the fuel rods and the nuclear reaction will rapidly generate heat, which is used to propel the missile... if the reactor overheats the control rods can be dropped down to stop the reaction... the engine wont go cold but will stop heating up and with the airflow drawing heat from the reactor it should stop overheating and start to cool down to a safer temperature...

In fact you could modify the reactor so that control rods remain in place and when the target is reached the missile climbs to 5,000m altitude and drops its warhead or 4-5 warheads over the targets and then the extra control rods can be raised to super heat the engine and melt it down so the missile crashes with a melted down reactor deep inside enemy territory somewhere as a bonus little present...

Operating at higher altitude might require more heat from the reactor so that extra heat potential could make it able to fly faster at higher altitudes too.

I don't know.
Maybe they will found a way to test it by other ways to run it in big circle.
Maybe the underwing can work, that better than see a reactor flying rounds above Siberia for days.

Well the D-30 engines on the Il-76 generate 14 tons of thrust for takeoff, but during cruise they only generate 2 tons of thrust each... perhaps replace two engines with these ramjet designs, and put PS-90 engines on the other two positions and use a really long runway... once airborne see if you can stay airborne with the ramjets... because they will not be using any fuel.... imagine a scaled up nuclear ramjet that can put out 2-3 tons thrust...

the rumors about failed tests from the Pankovo site might have some substance.
The latest images (August) of the Pankovo facilities show that all equipment is removed from all sites - including the protective tent at the launch site itself!
Only the large hangar at the former airfield remains.
The removal of the equipment probably indicates that no further test are expected from there - at least for the foreseeable future.
But what does that mean? Where would they test the nuclear engine if not at Novaja Semlja? Is that already an indication of the end of the program?

IMHO there is still a long way to go to get that nuclear engine work and to have a reliable weapon easy to handle for the crew.

GarryB wrote:

You are comparing apples with oranges... hydrogen fuel is used (with oxygen) because it is light and accelerates fast in the combustion reaction.

With ion propulsion it is different as it uses magnetism for acceleration... any material can be used... just strip off an electronic and it has an electric charge and can be manipulated easily by magnetic field.

Xenon was chosen because of its very high performance, but nitrogen is orders of magnitude cheaper and much more abundant... it is a bit like airships... hydrogen is cheaper and offers better performance but Helium was safer but expensive.

Old airships used Helium for safety but new airships can use hydrogen fuel cells, and lots of fire retardant technologies to minimise the risk of fire allowing much cheaper operations.

Nuclear thermal rocket has to use hydrogen, if it using helium ( second best candidate in the periodic table ) then the performance of it will be inferior compared to the chemical rockets.

A nuclear ramjet will use the gases the aircraft or missile the ramjet propels is flying through...

I don't think that the reactor has that much margin to locally shut it down and still operating.

I have never heard of any nuclear reactor that "drops cores" except in the Movies like Star Trek.

You need to have the reactor in an inactive state otherwise its engine will always be running... how would you store them?

I would expect in operation when the solid rocket booster engine fires and launches the missile control rods will be raised to expose the fuel rods and the nuclear reaction will rapidly generate heat, which is used to propel the missile... if the reactor overheats the control rods can be dropped down to stop the reaction... the engine wont go cold but will stop heating up and with the airflow drawing heat from the reactor it should stop overheating and start to cool down to a safer temperature...

In fact you could modify the reactor so that control rods remain in place and when the target is reached the missile climbs to 5,000m altitude and drops its warhead or 4-5 warheads over the targets and then the extra control rods can be raised to super heat the engine and melt it down so the missile crashes with a melted down reactor deep inside enemy territory somewhere as a bonus little present...

Operating at higher altitude might require more heat from the reactor so that extra heat potential could make it able to fly faster at higher altitudes too.

Ok, so same theory, .

Ion engine : it requiring only electrical source to operate, it can be reactor, solar cell, battery, RTG, steam turbine.
The reaction mass theoretically can be anything, but in practice it has many design considerations, including but not limited to be easy to storage, don't damage the cathode/anode, be preferably gas / liquid during the operations condition of the spacecraft without complex heating equipment.

Based on those requirements it needs to be noble gas, with high mass .So , they using the xenon.

Nuclear thermal ROCKET engine:
It can work only with hydrogen. Everything else will be worst than a simple chemical rocket.
However this engines can use the hydrogen as moderator in the reactor, so the nuclear reaction would be proportional to the density of hydrogen flowing through the core.
Means it is a self regulating engine.
If the engine fail, then it just impact the ground in one piece ( depending on the design).

Nuclear ramjet engine:
So, the air has no moderating capability. It means that if the flow in the engine decreasing ( even locally) then the reactor core ( the air flow thought of it) will overheat, melt and the derbies/vapour of the reactor core will go out from the engine with the air flow.
Means this engine has higher chance to fail than the hydrogen thermal rocket one, and if fail then it will not just simply impact the ground in one piece, but it will disperse the reactor core over a huge area prior of impact.
So, it is not so easy to test.


Remark: all low earth orbit nuclear reactor system had core evacuation/ejection mechanism, to eject the reactor core to a safe parking orbit.
It is a basic feature : )