Why did RP-1/H2O2 engines never took off?

[fredinno]

https://en.m.wikipedia.org/wiki/New_Shepard#Propulsion_module

https://en.m.wikipedia.org/wiki/Bristol_Siddeley_Gamma

 

In the late 1950s to 1960s, British companies experimented with RP-1/H2O2 engines. Burning an 86 Percent mixture of Hydrogen Peroxide and water onto RP-1, (the peroxide which was passed through a catalyst to first decompose it) the rocket engines managed to pull a 265s ISP, and lead to the Gamma Family of rocket engines, which powered the Black Knight and Black Arrow Launch Vehicles. Since RP-1/H2O2 is hypergolic, no ignition source was required, and the engines were very simple and reliable- there were no engine failures through the history of the Gamma family of engines. Additionally, H2O2 is non-toxic- thus the Gamma engines had most of the advantages of a Hypergolic engine without the toxic propellants and exhaust.

 

This kind of make you wonder why this propellant combination was abandoned for the most part. Though there were revivals by companies like Beal Aerospace and now Blue Origin for use on the BE-2 engine, H2O2/RP-1 has remained largely unused. Yes, rocket engine development is expensive, and it is less efficient than cryogenic, or even the Titan IV's hypergolic propellants (302 s ISP for Titan IV, and 266s ISP for a Gamma 8 RP-1/Peroxide engine) but it would still make for a good throttlable cheap SRB alternative. Also, the good reliability records and experience with the Gamma engines made me wonder why they decided against a similar engine's use on say, the Ariane 1- or why Blue Origin decided against using it for New Shepard, and instead using H2LOX.

[Laie]

Lack of energy I'd say. H2O2 weighs slightly more than pure oxygen, and is only half as effective as an oxidizer. You'd need a very special application for the side effects to outweigh this basic deficiency.

I don't think you could make a cheap SRB alternative with any liquid fuel. SRBs are quite cheap already, and liquid rockets are necessarily more complicated.

[fredinno]

10 minutes ago, Laie said:

Lack of energy I'd say. H2O2 weighs slightly more than pure oxygen, and is only half as effective as an oxidizer. You'd need a very special application for the side effects to outweigh this basic deficiency.

I don't think you could make a cheap SRB alternative with any liquid fuel. SRBs are quite cheap already, and liquid rockets are necessarily more complicated.

Well, it could compete in the sense of greater performance than SRBs, as peroxide engines are likely about as simple as you can get for liquid rockets, and Rp-1/Peroxide has less dry mass and higher ISP.

[Ten Key]

Excerpt from John Clark's Ignition!

Quote

Hydrogen peroxide decomposes according to the equation H₂O₂ --> H₂O + 1/2 O₂, with the evolution of heat. Of course, WFNA (White Fuming Nitric Acid) also decomposed, but not exothermically. The difference is crucial: It meant that peroxide decomposition is self-accelerating. Say that you have a tank of peroxide, with no efficient means of sucking heat out of it. Your peroxide starts to decompose for some reason or other. This decomposition produces heat, which warms up the rest of the peroxide, which naturally then starts to decompose faster-- producing more heat. And so the faster it goes the faster it goes until the whole thing goes up in a magnificent whoosh or bang as the case may be, spreading superheated steam and hot oxygen all over the landscape. 

It goes on from there with a discussion of all the many things that can start the decomposition process. There is also a discussion of hydrogen peroxide's less than desirable freezing point. 

[Steel]

42 minutes ago, fredinno said:

Well, it could compete in the sense of greater performance than SRBs, as peroxide engines are likely about as simple as you can get for liquid rockets, and Rp-1/Peroxide has less dry mass and higher ISP.

The ignition is not anywhere near the most complex thing in a liquid engine, yes you can make simple, pressure-fed hypergolic engines (see the Apollo LEM ascent engine) but for any lifter engine you will want a bit more performance, meaning a more complex engine. Then you have to consider, once you've gobe through the bother of designing an engine, why not use better propellants?

I have to say, however, that as a brit I would love to see the technology developed and used in a new generation of British orbital rockets. The reliability is hard to argue with, its just the lack of performance that really lets it down

Edited January 13, 2016 by Steel

[Kryten]

Peroxide/Kerosene is used on the upper stage of CZ-6; presumably as they didn't want to deal with LOX on a relatively small orbital adjustment stage, and for synergy with CZ-6's peroxide roll thrusters and SAST's work on peroxide/kerosene upper stages.

[RuBisCO]

H2O2/RP1 is safer then N2O4/MMH and has higher density, 1.31 g/ml verse 1.20 g/ml, but has lower ISP of 319 s verse 336 s. No matter what the H2O2 is not going to be stable over periods of years, unlike MMH and N2O4. N2O4/MMH require no ignition system as they are hypergolic, while H2O2 needs a precatalyst to decompose the H2O2 which should then hopefully be hot enough to ignite the fuel in a consistent manner.    

I could see H2O2/RP1 making sense for attitude control of a reusable spacecraft that is in orbit a few months as most, refueling would not require hazmat suits and intensive protections.

[Laie]

3 hours ago, fredinno said:

Well, it could compete in the sense of greater performance than SRBs,

Define "performance". In terms of raw thrust SRBs are hard to beat. High mass and low ISP notwithstanding, they have become the go-to solution for getting stuff off the ground. Maybe I'm naive, but I assume this is so for a reason.

 

[cantab]

Storable hypergolic propellants were pioneered by the military to fuel ballistic missiles. I'm guessing neither the US Army nor the Red Army was overly concerned about using toxic fuels, not when designing and building the missiles was what both sides thought would avoid them losing a nuclear war.

(Edit, and yes, I remember now it was probably the Air Force not the Army doing the missiles, but the point stands)

Edited January 14, 2016 by cantab

[fredinno]

6 hours ago, RuBisCO said:

H2O2/RP1 is safer then N2O4/MMH and has higher density, 1.31 g/ml verse 1.20 g/ml, but has lower ISP of 319 s verse 336 s. No matter what the H2O2 is not going to be stable over periods of years, unlike MMH and N2O4. N2O4/MMH require no ignition system as they are hypergolic, while H2O2 needs a precatalyst to decompose the H2O2 which should then hopefully be hot enough to ignite the fuel in a consistent manner.    

I could see H2O2/RP1 making sense for attitude control of a reusable spacecraft that is in orbit a few months as most, refueling would not require hazmat suits and intensive protections.

Well, technically H2O2 is hypergolic (not a STORABLE hypergolic though) as it does not need an active igniter to ignite- just pass  the peroxide though the catayst and then the fuel (in theory, at least)

Also, peroxide monopropellant is probably better for attitiude control. I was more wondering about low cost SLVs.

3 hours ago, cantab said:

Storable hypergolic propellants were pioneered by the military to fuel ballistic missiles. I'm guessing neither the US Army nor the Red Army was overly concerned about using toxic fuels, not when designing and building the missiles was what both sides thought would avoid them losing a nuclear war.

(Edit, and yes, I remember now it was probably the Air Force not the Army doing the missiles, but the point stands)

Civilian launch providers probably do care about toxicity though.

Edited January 14, 2016 by fredinno

[RuBisCO]

57 minutes ago, fredinno said:

Well, technically H2O2 is hypergolic (not a STORABLE hypergolic though) as it does not need an active igniter to ignite- just pass  the peroxide though the catayst and then the fuel (in theory, at least)

Also, peroxide monopropellant is probably better for attitiude control. I was more wondering about low cost SLVs.

Civilian launch providers probably do care about toxicity though.

You can double the delta-v by injecting RP-1 in the exhaust of a H2O2 mono-propellant thruster. The catalyst are still far more complicated then simply mixing the fuel and oxidizer together as in N2O4/MMH. 

The cost of dealing with fueling and unfueling the Space Shuttles orbital thrusters was a major problem.

Edited January 14, 2016 by RuBisCO

[Temstar]

4 hours ago, cantab said:

I'm guessing neither the US Army nor the Red Army was overly concerned about using toxic fuels, not when designing and building the missiles was what both sides thought would avoid them losing a nuclear war.

Haha, yeah ICBMs by their nature have some pretty unusual manufacturing requirement. Back in the early days of ICBM when they were still fueled by RP-1 the original specification for this fuel had looser requirement than it does now, as a result rocket engine people were complaining that if the RP-1 fuel could be refined to a higher standard (to avoid polymerization when used in regenerative cooling) the rockets will work better. The military didn't want this though because they argued that in a war situation where refinery could be targets making the fuel standard too strict will affect their ability to fuel more missiles.

But then it was pointed out to them that if there ever was a situation that called for "FIRE ALL THE ICBMS", there will soon be no "refinery capacity problem" to worry about anyway.

[fredinno]

3 hours ago, RuBisCO said:

You can double the delta-v by injecting RP-1 in the exhaust of a H2O2 mono-propellant thruster. The catalyst are still far more complicated then simply mixing the fuel and oxidizer together as in N2O4/MMH. 

The cost of dealing with fueling and unfueling the Space Shuttles orbital thrusters was a major problem.

I was thinking peroxide would make a good OMS pod, but it decomposes, so... What's the decomposition rate for H2O2?

[Workable Goblin]

11 hours ago, Laie said:

Define "performance". In terms of raw thrust SRBs are hard to beat. High mass and low ISP notwithstanding, they have become the go-to solution for getting stuff off the ground. Maybe I'm naive, but I assume this is so for a reason.

 

It's because solid rockets are useful military technology. In the countries that use solids extensively, in particular the United States, India, and France (which has been behind most ESA launcher development until recently), large solid rockets were developed in parallel with early liquid-fueled orbital rockets for ballistic missiles. This meant that the technology was already developed and paid for when the question of how to improve early orbital rockets came up, and it was therefore cheaper to just tack some on to existing designs (like the Titan II or Delta) or incorporate them in new designs (like the Shuttle) than to develop new liquid engines. Once they started to be used extensively, those respective agencies gained experience with using solids and an industrial base geared towards building solids, so it became even easier and cheaper to use solids instead of liquids, and so on and so forth. Therefore, they use solids extensively.

Japan, which also uses solids extensively, got there through a slightly different route; their space program started off with oversized sounding rockets, which were usually solid rockets instead of liquid rockets due to ease of handling, and their early "heavy" rockets were license-built copies of the Delta, which relied on solid boosters for the reasons given above. Therefore, they already had an experience base in solids by the time they were designing their own rockets (the H-II), which combined with the fact that a solid rocket industry would give them a credible ability to build a ballistic missile led them to continue using SRBs.

Contrast this with the Soviet Union/Russia and China, which only developed solid-fueled ballistic missiles long after the question of how to build more advanced orbital rockets came up. In those countries, the use of solid boosters on space launch vehicles is very rare, instead they tend to use all-liquid solutions, for more or less the same reason that Western countries and India use solids so often; they already had rockets developed for the missile program which they could leverage for new vehicles, and once they started doing that it was always easier to keep using liquid engines than to switch course midstream. This was modified somewhat by the fact that solids do have genuine advantages over liquids for military uses, so they did tend to introduce solid rockets eventually, but in a much more limited way than the countries which had switched horses earlier, as it were.

[wumpus]

"Old hands" of missile/rocket design tend to complain about solid rockets' tendency to explode.  It might not be high enough to prevent even the most expensive satellites (about 1% per launch), but did at least contribute to one lost shuttle.  From what I understand, controls and inspection to get SRBs up to this level of safety tends to pump the price up to liquid rocket levels.

Orbital/ATF uses them, but only military surplus (obviously a cheap way to get a booster).  As far as I know, the KSP SRB prices are lowered to improve the game, but don't really reflect reality (there's also the issue that while you [almost always] can't throttle liquid rockets like you can in KSP, you preset the thrust of an SRB to change over the launch.  The shuttle did this to keep either the G forces down and/or limit the aerodynamic pressure on the orbiter (it couldn't throttle the SSMEs).

This annoys me as I am one of the bigger SRB fans in KSP.

[cantab]

True, civilian launch companies will be more concerned about toxicity, but the technology of the toxic-hypergolic engines is ready while the kerosene-peroxide engines are much less ready. It's the same situation as Workable discussed with respect to solids.

The Shuttle engines could actually throttle down to 2/3rds of their normal thrust. However the thrust of the boosters was vastly greater than that of the liquid engines, hence to make any significant difference to total thrust requires designing it into the boosters. The Shuttle boosters, and many others, could also vector thrust - a big omission from KSP's solids.

[Ten Key]

8 hours ago, fredinno said:

I was thinking peroxide would make a good OMS pod, but it decomposes, so... What's the decomposition rate for H2O2?

That's the rub. H₂O₂ is very sensitive to any impurities, and this has a significant effect on the rate of decomposition. Another excerpt from Ignition!

Quote

The only thing to do was to keep the peroxide in a tank made of something that didn't catalyze its decomposition (very pure aluminum was best) and to keep it clean. The cleanliness required was not merely surgical-- it was levitical. Merely preparing an aluminum tank to hold peroxide was a project, a diverting ceremonial that could take days. Scrubbing, alkaline washes, acid washes, flushing, passivation with dilute peroxide-- it went on and on. And even when it was successfully completed, the peroxide would still decompose slowly; not enough to start a runaway chain reaction, but enough to build up an oxygen pressure in a sealed tank, and make packaging impossible. And it is a nerve-wracking experience to put your ear against a propellant tank and hear it go "glub" -- long pause -- "glub" and so on. After such an experience many people, myself (particularly) included, tended to look dubiously at peroxide and to pass it by on the other side.

And on top of all of that, H₂O₂ has the same freezing point as water. There's a reason the US Navy stopped using peroxide torpedoes. 

As an aside, if you're the slightest bit interested in rocket propellants, I highly recommend Ignition! It's informative and funny, and if you can manage to lay your hands on a copy it's well worth reading.  

Edited January 14, 2016 by Ten Key

[RuBisCO]

10 hours ago, fredinno said:

I was thinking peroxide would make a good OMS pod, but it decomposes, so... What's the decomposition rate for H2O2?

Well that depends on what is used as inhibitors, but using Soyuz as a standard, it is claimed that its 6 months stand-by endurance is limited by decomposition of its H2O2 thruster for attitude control of the re-entry capsule. So as a OMS, H2O2 works fine as long as your not planning on staying up there for more than 6 months.

[Kryten]

 

5 minutes ago, RuBisCO said:

Well that depends on what is used as inhibitors, but using Soyuz as a standard, it is claimed that its 6 months stand-by endurance is limited by decomposition of its H2O2 thruster for attitude control of the re-entry capsule. So as a OMS, H2O2 works fine as long as your not planning on staying up there for more than 6 months.

Which is a tiny, tiny niche. It's not really worth developing a whole propulsion technology for.

[Steel]

3 hours ago, Ten Key said:

As an aside, if you're the slightest bit interested in rocket propellants, I highly recommend Ignition! It's informative and funny, and if you can manage to lay your hands on a copy it's well worth reading.  

I wish I could get a copy, I've tried for God knows how long! From my experience it's near impossible to get hold of a copy in the UK unless you're extremely fortunate with your timing.

[RuBisCO]

1 hour ago, Kryten said:

 

Which is a tiny, tiny niche. It's not really worth developing a whole propulsion technology for.

Considering the expensive of N2O4/MMH there is in fact a lot of research into safer "cleaner" mono-propellants for attitude control and orbital maneuvers. I could see H2O2/RP-1 having taken-off as a AC and OM fuel in an alternate history, but in our reality, shaped by the funding and political climate for space that we have had, yeah I agree it is never going to happen. 

 

[RuBisCO]

From the book Ignition! by John Drury Clark, a book I advice anyone that loves rockets read, A whole chapter on H2O2

https://books.google.com/books?id=WpMfCwAAQBAJ&pg=PA66&source=gbs_toc_r&cad=4#v=onepage&q&f=false

[fredinno]

16 hours ago, wumpus said:

"Old hands" of missile/rocket design tend to complain about solid rockets' tendency to explode.  It might not be high enough to prevent even the most expensive satellites (about 1% per launch), but did at least contribute to one lost shuttle.  From what I understand, controls and inspection to get SRBs up to this level of safety tends to pump the price up to liquid rocket levels.

Orbital/ATF uses them, but only military surplus (obviously a cheap way to get a booster).  As far as I know, the KSP SRB prices are lowered to improve the game, but don't really reflect reality (there's also the issue that while you [almost always] can't throttle liquid rockets like you can in KSP, you preset the thrust of an SRB to change over the launch.  The shuttle did this to keep either the G forces down and/or limit the aerodynamic pressure on the orbiter (it couldn't throttle the SSMEs).

This annoys me as I am one of the bigger SRB fans in KSP.

Actually, OrbitalATK makes their own CASTOR rocket stages (based off the retired Peacekeeper stages) for SLV use. https://en.wikipedia.org/wiki/Castor_%28rocket_stage%29 not to mention the Pegasus rocket stages.

13 hours ago, Ten Key said:

That's the rub. H₂O₂ is very sensitive to any impurities, and this has a significant effect on the rate of decomposition. Another excerpt from Ignition!

And on top of all of that, H₂O₂ has the same freezing point as water. There's a reason the US Navy stopped using peroxide torpedoes. 

As an aside, if you're the slightest bit interested in rocket propellants, I highly recommend Ignition! It's informative and funny, and if you can manage to lay your hands on a copy it's well worth reading.  

The freezing point should not really be an issue if you add small heaters, something that was done in the Apollo H2+O2 tanks.

11 hours ago, Kryten said:

 

Which is a tiny, tiny niche. It's not really worth developing a whole propulsion technology for.

Well, it should be fine for most LEO applications- just makes it impossible to use as a CRV or emergency return vehicle of some sort. The Shuttle did fine with a much more limited lifespan.

Edited January 15, 2016 by fredinno

[wumpus]

7 hours ago, fredinno said:

Actually, OrbitalATK makes their own CASTOR rocket stages (based off the retired Peacekeeper stages) for SLV use. https://en.wikipedia.org/wiki/Castor_%28rocket_stage%29 not to mention the Pegasus rocket stages.

The linked article quotes a CASTOR 120 as being sold for  $17.5 million bucks for one (of four stages) and a ~1 ton payload.  Also both  rockets the linked article mentions (Orbiting carbon observatory and Glory) failed.  The H-IIA (based on the CASTOR) seems to be doing well, but I can't tell if it is manufactured by ATK(/Orbital) or Mitsubishi (the booster specific wiki is in Japanese).  (Vacuum) ISP is 280, but success is limited (note that one of the launches, the Glory IRC, failed due to rocket assembly issues and wasn't motor specific).

These really don't resemble KSP (cheap and inefficient) SRBs at all.

[shynung]

14 hours ago, fredinno said:

The freezing point should not really be an issue if you add small heaters, something that was done in the Apollo H2+O2 tanks.

On 1/14/2016 at 3:36 AM, Kryten said:

That's one more part that may fail miserably. Remember Apollo 13?

There's a reason why folks like J.D. Clark was paid handsomely to find propellants with a reasonable range of temperatures in which it is in liquid form. Otherwise, we would have never had MMH, UDMH, or IRFNA (inhibited red fuming nitric acid, HNO₃ with some N₂O₄ and HF mixed in).

On 1/14/2016 at 4:55 AM, Steel said:

I wish I could get a copy, I've tried for God knows how long! From my experience it's near impossible to get hold of a copy in the UK unless you're extremely fortunate with your timing.

It's out of print. You can read it here.