Author Topic: Next best propellant for abort engines after hydrazine et al  (Read 10662 times)

Offline Proponent

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I'm paying attention to nofbx, I think it's a promising propellant .I haven't got any information about it since 2013.

My guess would be that 2013 is when Firestar realized that NOFBX was not going to work.  In retrospect, it does seem too good to be true.

EDIT:  "wasn't not" -> "was not"
« Last Edit: 03/28/2017 11:06 PM by Proponent »

Offline brickmack

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A few people have mentioned AF-M315E, the GPIM propellant. This is a very promising option for satellite propulsion (high ISP, high density, more easily storable than most other fuels, cheap), but isn't close to relevant to OPs question. The most powerful thruster in serious development so far with that propellant produces a whopping 22 newtons of thrust, you can never achieve a TWR greater than 1 with engines of that size even if you used thousands of them. Maybe in a few decades someone will come up with something, but for now there is zero design history relevant to an abort motor, and not even any concepts I can find for how to make such a thing work
« Last Edit: 03/26/2017 10:04 PM by brickmack »

Offline savuporo

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Just go with LMP-103S. Space qualified, and has actual commercial wins
Orion - the first and only manned not-too-deep-space craft

Offline sevenperforce

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The water weight of HTP makes it very very thrusty when used to oxidize hydrocarbons (with which it is hypergolic), and its decomposition can be used to run a turbopump off a catalyst, so it seems like a pretty good solution all-around.

Offline Arch Admiral

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H2O2 has a safety record far worse that hydrazine or N2O4. It was strongly promoted by one Dr. Helmut Walter in Nazi Germany, and was widely copied around the world due to the unjustified reputation German engineering had in those days. The problem is that it blows up on contact with anything organic plus a lot of common metals. It has been dropped in torpedos, in submarine engines, and in military missiles. NASA dropped it after Mercury. The UK rocket program dropped in the 1950s. Probably the worst H2O2 disaster was RNS KURSK.

The only remaining user is Roscosmos, in the Soyuz & Progress thrusters and the R-7 booster turbopumps. They just don't have the money to replace it.

This whole "green propellant" movement is really a push for "nontoxic propellant" and is based on an exaggerated fear of the conventional fuels. In the space shuttle program there was one serious spill  that zorched a few tiles, and one leak that kept a crew shut up in the Orbiter for 90min after landing. Pretty good for 135 missions.

Offline brickmack

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This whole "green propellant" movement is really a push for "nontoxic propellant" and is based on an exaggerated fear of the conventional fuels. In the space shuttle program there was one serious spill  that zorched a few tiles, and one leak that kept a crew shut up in the Orbiter for 90min after landing. Pretty good for 135 missions.

Beyond the risk of an accident, working with such horrendously toxic propellants still just isn't cheap. The safety requirements significantly increase costs, I've seen cost figures in the low millions for fueling a typical spacecraft, almost all of which is related to safety accommodations rather than the material itself (though those WERE studies by companies involved in green propellants, so maybe a bit of exaggeration). If you can get rid of that, it would bring down the cost a lot

Its also more generally a push for new propellants, which just happen to be friendlier to work with. Theres been very little serious research into new spacecraft propellants in ages even though relevant fields have advanced so much in that time. Its not a coincidence that most of these "green" propellants also are denser, easier to store, and more efficient than the current norm

Offline savuporo

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..Beyond the risk of an accident, working with such horrendously toxic propellants still just isn't cheap.
And that's both operational cost which are more often quoted, but also development costs. Developing and qualifying hydrazine thusters isnt cheap.
Orion - the first and only manned not-too-deep-space craft

Offline sevenperforce

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H2O2 has a safety record far worse that hydrazine or N2O4. It was strongly promoted by one Dr. Helmut Walter in Nazi Germany, and was widely copied around the world due to the unjustified reputation German engineering had in those days. The problem is that it blows up on contact with anything organic plus a lot of common metals. It has been dropped in torpedos, in submarine engines, and in military missiles. NASA dropped it after Mercury. The UK rocket program dropped in the 1950s. Probably the worst H2O2 disaster was RNS KURSK.
Oh, yes, it's very nasty stuff if you make the mistake of treating it carelessly.

Offline speedevil

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The water weight of HTP makes it very very thrusty when used to oxidize hydrocarbons (with which it is hypergolic), and its decomposition can be used to run a turbopump off a catalyst, so it seems like a pretty good solution all-around.

I'm fairly sure that HTP isn't hypergolic - that is, self-igniting, with hydrocarbons in rocket use.

All of the research I found on this when looking at it about a decade ago all agreed that either an ignitor or catalyst pack was needed.
You can't just spray H2O2 and kerosene and have it ignite. (at least not other than as a possible accident)

Offline sevenperforce

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The water weight of HTP makes it very very thrusty when used to oxidize hydrocarbons (with which it is hypergolic), and its decomposition can be used to run a turbopump off a catalyst, so it seems like a pretty good solution all-around.

I'm fairly sure that HTP isn't hypergolic - that is, self-igniting, with hydrocarbons in rocket use.

All of the research I found on this when looking at it about a decade ago all agreed that either an ignitor or catalyst pack was needed.
You can't just spray H2O2 and kerosene and have it ignite. (at least not other than as a possible accident)
Well, yeah, cold HTP won't ignite on contact with RP-1, but a reusable catalyst will do the trick. It's a lot closer to hypergolic performance than to systems which require a separate ignitor.
« Last Edit: 04/05/2017 01:44 PM by sevenperforce »

Offline smfarmer11

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Well as far as simplicity goes, you can't really beat a solid fuel system. Solid rockets are extremely reliable , quick to start. Although I feel that's against the tide of this thread.

Offline brickmack

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Well as far as simplicity goes, you can't really beat a solid fuel system. Solid rockets are extremely reliable , quick to start. Although I feel that's against the tide of this thread.

Not reusable or testable, dead mass in a nominal flight, dangerous to work with on the ground, and tends to result in excessive acceleration.

Offline Jim

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Well as far as simplicity goes, you can't really beat a solid fuel system. Solid rockets are extremely reliable , quick to start. Although I feel that's against the tide of this thread.

Not reusable or testable, dead mass in a nominal flight, dangerous to work with on the ground, and tends to result in excessive acceleration.

Just like ejection seats.  So what is your point?

Offline Patchouli

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Well as far as simplicity goes, you can't really beat a solid fuel system. Solid rockets are extremely reliable , quick to start. Although I feel that's against the tide of this thread.

Not reusable or testable, dead mass in a nominal flight, dangerous to work with on the ground, and tends to result in excessive acceleration.

Solid abort motors do not necessarily have to be dead mass dead mass during a nominal flight
The Kliper space craft would,have fired it's abort motors in pairs to help with orbital insertion.
http://www.russianspaceweb.com/kliper_history.html
« Last Edit: 05/05/2017 03:29 AM by Patchouli »

Offline Katana

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For abort engines only, solids are good enough since Apollo.

For multi purpose engines, just roll back to WRFNA+Amines,standard hypergolics in 1950s before more toxic NTO+MMH.
Somewhat low performance, but yet higher performance than AF-M315E monopropellant.

NOFBX is a mixture of liquefied N2O and hydrocarbon gas, more horribly spontaneously explosive than H2O2.
N2O itself is a spontaneously explosive monopropellant (the SpaceShip2 explosion in 2007).

Offline Dante80

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A few people have mentioned AF-M315E, the GPIM propellant. This is a very promising option for satellite propulsion (high ISP, high density, more easily storable than most other fuels, cheap), but isn't close to relevant to OPs question. The most powerful thruster in serious development so far with that propellant produces a whopping 22 newtons of thrust, you can never achieve a TWR greater than 1 with engines of that size even if you used thousands of them. Maybe in a few decades someone will come up with something, but for now there is zero design history relevant to an abort motor, and not even any concepts I can find for how to make such a thing work

Coming back to this, if the concept is tested and works as advertised, what would be the problem with scaling this up? If it is under consideration for military missiles, can't it not work in something like a SuperDraco class setting?

What I am asking is whether the problem is simply TRL for scaling (someone needs to pay and work on this) or a hard blocker in scaling all-together (like electric propulsion requiring ridiculous amounts of electricity to do serious thrust).
« Last Edit: 06/10/2017 06:53 PM by Dante80 »

Offline brickmack

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Coming back to this, if the concept is tested and works as advertised, what would be the problem with scaling this up?

...

The big problem I was thinking of those is that this is a catalytic monopropellant, you've got to get the entire propellant stream to contact the catalyst bed. Thrust scales roughly with propellant volume, but the volume of propellant that can be usefully burned scales with surface area. Thats a problem. Hypergolic bipropellants are easy by comparison, just contact the 2 chemicals together. I don't know how quickly this will stop scalability, but given we're talking roughly a 4000x scaling factor between the current "high thrust" GR-22 and SuperDraco, I'd be surprised if it'll scale *that* far.

Do you have any information on it being used in missiles? I couldn't find anything on the subject. I'd take a guess (given that the US military has long preferred solid fueled missiles for a variety of reasons) this is just for roll control thrusters or a final targetting upper stage, neither of which needs thrust hugely greater than whats already demonstrated

Offline Katana

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Coming back to this, if the concept is tested and works as advertised, what would be the problem with scaling this up?

...

The big problem I was thinking of those is that this is a catalytic monopropellant, you've got to get the entire propellant stream to contact the catalyst bed. Thrust scales roughly with propellant volume, but the volume of propellant that can be usefully burned scales with surface area. Thats a problem. Hypergolic bipropellants are easy by comparison, just contact the 2 chemicals together. I don't know how quickly this will stop scalability, but given we're talking roughly a 4000x scaling factor between the current "high thrust" GR-22 and SuperDraco, I'd be surprised if it'll scale *that* far.

Do you have any information on it being used in missiles? I couldn't find anything on the subject. I'd take a guess (given that the US military has long preferred solid fueled missiles for a variety of reasons) this is just for roll control thrusters or a final targetting upper stage, neither of which needs thrust hugely greater than whats already demonstrated
https://www.rocket.com/files/aerojet/documents/Capabilities/PDFs/GPIM%20AF-M315E%20Propulsion%20System.pdf
AF-M315E offers higher performance than hydrazine, yields 12% higher Isp (257 vs. 235 sec)
=========
Isp only better than monoprop hydrazine (catalytic decompose), yet much inferior than biprops.

Offline Nilof

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The water weight of HTP makes it very very thrusty when used to oxidize hydrocarbons (with which it is hypergolic), and its decomposition can be used to run a turbopump off a catalyst, so it seems like a pretty good solution all-around.

I'm fairly sure that HTP isn't hypergolic - that is, self-igniting, with hydrocarbons in rocket use.

All of the research I found on this when looking at it about a decade ago all agreed that either an ignitor or catalyst pack was needed.
You can't just spray H2O2 and kerosene and have it ignite. (at least not other than as a possible accident)

Hot decomposed HTP is hypergolic with Kersosene though. Any fuel-oxidizer composition is hypergolic if you just make the temperature high enough.  ;)
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline John-H

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The water weight of HTP makes it very very thrusty when used to oxidize hydrocarbons (with which it is hypergolic), and its decomposition can be used to run a turbopump off a catalyst, so it seems like a pretty good solution all-around.

I'm fairly sure that HTP isn't hypergolic - that is, self-igniting, with hydrocarbons in rocket use.

All of the research I found on this when looking at it about a decade ago all agreed that either an ignitor or catalyst pack was needed.
You can't just spray H2O2 and kerosene and have it ignite. (at least not other than as a possible accident)

Hot decomposed HTP is hypergolic with Kersosene though. Any fuel-oxidizer composition is hypergolic if you just make the temperature high enough.  ;)

Once the engine is running, do you still need a catalyst. I can't picture HTP going into a fully burning hot engine and  putting the fire out.

John

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