Author Topic: "Diesel" type rocket engine?  (Read 22183 times)

Offline JasonAW3

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"Diesel" type rocket engine?
« on: 03/15/2010 03:02 PM »
Ok,

     I kind of doubt that this is even possible, but I thought I'd throw it out for discussion anyway.

     Is a sort of "Diesel" style rocket engine possible?  I'm not talking of a motor that uses compression to achieve ignition, (although that WOULD be a neat trick!) but more along the lines of being able to use multiple types of liquid fuels and oxidizers in a standardized motorto achieve thrust, while still making the engine reusable?  I know that there would be massive issues involved, differences in ISP, engine masses, etc. but I figured that instead of having to have a dozen different engine types for each different combination of non-cryogenic fuel / oxidizer mix, one might be willing to make sacrifices for cheaper reliable engines.
     Yes, I KNOW that this most likely wouldn't work for Cryogenic engines, but what I want to know, is if there would be any advantage to this approach, and if so, would the sacrifices in performance be worth the lowered expense of a standardized engine design?
     And, would it be possible, through realtively low cost "kits", be possible to reconfigure the engine to run these different fuels more effeciently?  (Similar in concept to kits used to convert diesel engines on fuels from heating oil to kerosene, to ethanhol, to cooking oil, instead of diesel).

      I'd understand if there's a materials technology issue involved, but overall, I'm just wondering if this is something that could be done.

Jason
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Offline Jim

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Re: "Diesel" type rocket engine?
« Reply #1 on: 03/15/2010 03:47 PM »
look up tripropellant engines.   But generically, not practical for pump fed since the pumps are optimized for the fluid being moved. 

Also injectors are optimized. 


Also what says they will be "cheaper reliable engines."?  You are increasing the complexity and at the same time reducing efficiency.

Also why?
« Last Edit: 03/15/2010 03:52 PM by Jim »

Offline 93143

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Re: "Diesel" type rocket engine?
« Reply #2 on: 03/15/2010 05:00 PM »
Doesn't RL-10 run fine on LOX/CH4?

Offline strangequark

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Re: "Diesel" type rocket engine?
« Reply #3 on: 03/15/2010 05:45 PM »
Doesn't RL-10 run fine on LOX/CH4?

If youíre talking about CECE, I believe that there are variants to run one or the other, but the same engine cannot run both (I donít know for sure though, Iíve been trying to find out myself). I would suspect such an engine would have to have separate, dedicated turbopumps for the LH2 and CH4, given the density differences. Also, as Jim indicated, injection would suffer too. Propane and CH4 might be doable with a single design, but again, why?
« Last Edit: 03/15/2010 05:50 PM by strangequark »

Offline Rhyshaelkan

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Re: "Diesel" type rocket engine?
« Reply #4 on: 03/16/2010 12:05 AM »
Soybean oil rocket? :P

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Offline mmeijeri

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Re: "Diesel" type rocket engine?
« Reply #5 on: 03/16/2010 12:22 AM »
I can think of one potential application, far in the future: a lander engine capable of running on both LOX/methane and LOX/silane.

For moon applications this could be useful in combination with ISRU for the silicon and oxygen. Importing the required hydrogen (only useful if the reported ice deposits turn out not to be practical) could be done in the denser form of methane. During descent the engine would run on methane. Once on the ground the cargo of methane and any remaining propellant could be processed into silane using lunar silicon. The resulting carbon could then be used on the surface for things like plastics.

It could also be useful to have an engine capable of using both silane (possible with moon ISRU) and methane (easier on Mars, though silane would still remain possible).

All very speculative, and far, far in the future.
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Offline Propforce

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Re: "Diesel" type rocket engine?
« Reply #6 on: 03/16/2010 03:04 AM »

     Is a sort of "Diesel" style rocket engine possible?  I'm not talking of a motor that uses compression to achieve ignition, (although that WOULD be a neat trick!) but more along the lines of being able to use multiple types of liquid fuels and oxidizers in a standardized motorto achieve thrust, while still making the engine reusable? 
Jason

I gather that when you use the word "diesel" you are not referring to "the" diesel fuel as used in today's diesel engine.

But if you were, I am happy to inform you that kerosene fuel used in rocket engine is another form of "diesel" (in fact, a very dense form of hydrocarbon fuel). 

The difficulty in running a different density fuel is the same reason why it is difficult for your car to run on methanol as oppose to the regular gasoline (Octane).  You can do it, but need to change a few things to regulate to correct flow rate for combustion fuel/air ratio.

Another big difference is that, liquid rocket engines use fuel to cool its combustion chamber walls.  So not only considering combustion characteristic of fuels, its cooling capability (thermal stability, coking/gumming characteristics, etc.) needs to be considered along with combustion as well.

So until the energy crisis hits the space launch industry, a "flex fuel" rocket may not be in the cards yet.

Offline Rabidpanda

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Re: "Diesel" type rocket engine?
« Reply #7 on: 03/16/2010 03:35 AM »
I don't understand, why would you need a rocket that could run off of more than one fuel?  What hypothetical situation are you thinking of that would require this?

Offline RanulfC

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Re: "Diesel" type rocket engine?
« Reply #8 on: 03/16/2010 02:13 PM »
There has been a lot said on the RL-10 test-bench engine having been run on alternative fuels but not a lot of solid information.
From references in NASA and P&W studies and reports it would seem that the RL-10 has been run on Propane (Cyrogenic), LH2, Methane, even RP-1.
Some source quotes:

Newsgroups: sci.space.history,sci.space.policy
From: Henry Spencer <[email protected]>
Subject: Re: Black Horse (was: Re: HST as justification for STS)
Date: Wed, 23 Apr 1997 12:15:34 GMT

In article <[email protected]>,
Jacob McGuire  <[email protected]> wrote:
>>I believe you're thinking of a Russian engine, rather than the RL-10.
>>Redesigning a LOX/hydrogen engine to use H2O2/kerosene would be a much
>>bigger deal than redesigning a LOX/kerosene engine.
>
>  "CH4/O2 offers the second highest Isp (385 s)...  A significant
>disadvantage of CH4/O2 is that no flight-rated engine is
>currently available; development of one based on Pratt and Whitney RL-10
>engine technology would probably take three years and cost
>on the order of $30 million."

One reason to be reasonably confident in this low number is that the RL10
has already been run on LOX/CH4, with only minor modifications.  That was
done only experimentally, and you'd need a bit more work to certify that
configuration for production use, but it shouldn't be hard.

The RL10 has actually been run on a very wide variety of things.  For
fuels, hydrogen, methane, and propane have all been used; for oxidizers,
they've fired it on LOX, liquid fluorine, and FLOX (LOX/fluorine mixture).
Mixture ratio has been varied extremely widely, including successful tests
running severely oxidizer-rich.  And it's been throttled down to 1%.  An
amazingly tolerant engine.
--
   Henry Spencer
   [email protected]

Newsgroups: sci.space.tech
From: [email protected] (Henry Spencer)
Subject: RL10 (was Re: Aerial Propellant Transfer Revisited)
Date: Wed, 5 Jul 2000 13:44:51 GMT

In article <[email protected]>,
Kirk Voelcker  <[email protected]> wrote:
>> I>The RL-10 has been run on methane, yes?
>> And propane.  Only minor modifications were required...
>
>Do you have a URL or an ISBN that lists all the fuel combinations used by the
>RL-10?

Unfortunately, no...  The closest thing is the RL10 paper in NASA CP-3112,
"Space Transportation Propulsion Technology Symposium", 1990, which talks
a bit about alternate propellants and growth versions.  (NASA publications
do not have ISBNs, sorry.)  And even it doesn't mention some of the odder
things you can find in obscure NASA reports, e.g. the brief tests with
FLOX/1-butylene or the experiments at oxidizer-rich mixture ratios.  Nor
is it current enough to discuss the short-nozzle RL10 variant built for
DC-X.  The definitive RL10 history paper has yet to be written.
--
Henry Spencer   [email protected]
[email protected]


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Offline TyMoore

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Re: "Diesel" type rocket engine?
« Reply #9 on: 03/16/2010 02:32 PM »
I can think of one potential application, far in the future: a lander engine capable of running on both LOX/methane and LOX/silane.

For moon applications this could be useful in combination with ISRU for the silicon and oxygen. Importing the required hydrogen (only useful if the reported ice deposits turn out not to be practical) could be done in the denser form of methane. During descent the engine would run on methane. Once on the ground the cargo of methane and any remaining propellant could be processed into silane using lunar silicon. The resulting carbon could then be used on the surface for things like plastics.

It could also be useful to have an engine capable of using both silane (possible with moon ISRU) and methane (easier on Mars, though silane would still remain possible).

All very speculative, and far, far in the future.

If you can synthesize something like silane, surely you could synthesize something simpler like ethane. Then go with a propellant that is a known hypergol with liquid oxygen and is itself a liquid: tri-ethyl aluminum.
I'm not sure how thermally stable TEA is, so engine cooling could be a problem. Also, turbine gasses will contain hot aluminum oxide which could slag the turbine--same goes for silane. Pressure feed engine perhaps, and use ablative, radiative cooling on engine. Change out combustion and thrust chambers as needed for erosion control.

I don't know, it sure starts to sound complicated for a lunar ISRU scenario.

Offline TyMoore

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Re: "Diesel" type rocket engine?
« Reply #10 on: 03/16/2010 02:37 PM »
I just wanted to add: I once looked at the possibility of using a liquid parafin wax/aluminum emulsion burning with liquid oxygen as a very high-impulse density propellant. Trouble with this is that again, you have to insulate both tanks very well, and tens of thousands of gallons of hot wax and aluminum are going to radiate a heck of a lot of heat and couple it to 60,000 gallons or so of liquid oxygen. Refrigeration and heating in very close proximity is really complicated!

Also pressure drop in pintel injector is ferocious, not to mention the pumping power needed for moving a thick, dense slurry. And the need for an auxiliary jet pump to keep the fuel emulsion stirred up so the aluminum doesn't settle out.

Way too complicated.

I even had the crazy idea for painting the resulting booster a garish color to look like a big crayon! (Inspiration for kids, and all...)  :)
« Last Edit: 03/16/2010 02:42 PM by TyMoore »

Offline strangequark

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Re: "Diesel" type rocket engine?
« Reply #11 on: 03/16/2010 02:55 PM »
I can think of one potential application, far in the future: a lander engine capable of running on both LOX/methane and LOX/silane.

Not to derail this, but I've seen you mention silane a few times. Isn't it a problem that half of the combustion product (by weight) is silicon dioxide or silicon monoxide? Wouldn't you have massive efficiency losses because you're trying to expand a flow where half of the mass flow is in entrained solid particles? Not to mention your nozzle being sandblasted.

Offline mmeijeri

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Re: "Diesel" type rocket engine?
« Reply #12 on: 03/16/2010 03:42 PM »
If you can synthesize something like silane, surely you could synthesize something simpler like ethane.

The potential advantage of silane would be that you could get the silicon from ISRU. The methane conversion is just for finding a denser way to import hydrogen. You could also use ammonia or hydrazine.

Quote
Then go with a propellant that is a known hypergol with liquid oxygen and is itself a liquid: tri-ethyl aluminum.

The aluminium is a nice twist since that can also be sourced from ISRU. You could also consider metal-loaded gelled propellants.
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Offline FinalFrontier

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Re: "Diesel" type rocket engine?
« Reply #13 on: 03/16/2010 03:48 PM »
If you can synthesize something like silane, surely you could synthesize something simpler like ethane.

The potential advantage of silane would be that you could get the silicon from ISRU. The methane conversion is just for finding a denser way to import hydrogen. You could also use ammonia or hydrazine.

Quote
Then go with a propellant that is a known hypergol with liquid oxygen and is itself a liquid: tri-ethyl aluminum.

The aluminium is a nice twist since that can also be sourced from ISRU. You could also consider metal-loaded gelled propellants.
But is it worth it? You must weigh the costs plus any potential gains or penalties of using diesel. I seem to recall that this concept was investigated many times and they moved toward methan and "lighter" "cleaner" fuels instead. And idea that could utilize diesel would be a TAN "quad propellant" booster. This would use a small rp1 tank and an even smallert diesel tank. The primary first stage propellants would be lox and lh2. At lift off, the engine or engines would inject rp1 and the "diesel based" propellant into the chamber and nozzle respectivly. First the diesel tank would empty, then rp1. By the time the first stage is nearing meco, it would only be burning on lox lh2. This could pontentially eliminate the need for srbs, if the weight to thrust ratio was sufficent. Cost as well. But if it worked, this could also be a good idea for LRBS with the same engines and propellants attached to the core. Or just for a new LRB design to compete with ATK and SRB. Perhaps ares 1 could work if the first stage diameter did not change but instead of an srb and lrb was used.....
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Offline mmeijeri

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Re: "Diesel" type rocket engine?
« Reply #14 on: 03/16/2010 03:49 PM »
Not to derail this, but I've seen you mention silane a few times.

Heheh, I do find it an intriguing idea, just like metal loaded gels, hybrid propulsion, pressure-fed stages with composite casings, peroxide propulsion and a number of other concepts. :)

Quote
Isn't it a problem that half of the combustion product (by weight) is silicon dioxide or silicon monoxide?

I hadn't heard that objection before, maybe you're right. I vaguely recall there have been experiments at least with silane as an additive to hydrocarbons to promote ignition. I think Hidding mentioned it in one of his papers on silane.
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Offline mmeijeri

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Re: "Diesel" type rocket engine?
« Reply #15 on: 03/16/2010 03:51 PM »
But is it worth it? You must weigh the costs plus any potential gains or penalties of using diesel.

Oh, I was just thinking about how engines that can run on more than one fuel might be useful one day, not about diesel as a fuel. I guess we're getting off topic.
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Offline FinalFrontier

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Re: "Diesel" type rocket engine?
« Reply #16 on: 03/16/2010 03:52 PM »
I just wanted to add: I once looked at the possibility of using a liquid parafin wax/aluminum emulsion burning with liquid oxygen as a very high-impulse density propellant. Trouble with this is that again, you have to insulate both tanks very well, and tens of thousands of gallons of hot wax and aluminum are going to radiate a heck of a lot of heat and couple it to 60,000 gallons or so of liquid oxygen. Refrigeration and heating in very close proximity is really complicated!

Also pressure drop in pintel injector is ferocious, not to mention the pumping power needed for moving a thick, dense slurry. And the need for an auxiliary jet pump to keep the fuel emulsion stirred up so the aluminum doesn't settle out.

Way too complicated.

I even had the crazy idea for painting the resulting booster a garish color to look like a big crayon! (Inspiration for kids, and all...)  :)

On the other hand....if your looking for a new propellant why not use solid salami? Mythbusters proved it was possible to use salami as solid rocket fuel.....although there are drawbacks.....such as burnt salami smoke. :(
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Offline FinalFrontier

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Re: "Diesel" type rocket engine?
« Reply #17 on: 03/16/2010 03:53 PM »
But is it worth it? You must weigh the costs plus any potential gains or penalties of using diesel.

Oh, I was just thinking about how engines that can run on more than one fuel might be useful one day, not about diesel as a fuel. I guess we're getting off topic.
not off topic at all.
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Offline Patchouli

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Re: "Diesel" type rocket engine?
« Reply #18 on: 03/16/2010 04:02 PM »
Your best best for a multi propellant rocket that can essentially be a goat and run off any volatile you can find might be a gas core nuclear thermo rocket.

Solid core NTRs also may have some level of flexibility as well you could in theory make one able to use CO2 or water for example. 

A VASIMR engine depending on it's design also could have some level of flexibility.
« Last Edit: 03/16/2010 04:04 PM by Patchouli »

Offline FinalFrontier

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Re: "Diesel" type rocket engine?
« Reply #19 on: 03/16/2010 04:10 PM »
Your best best for a multi propellant rocket that can essentially be a goat and run off any volatile you can find might be a gas core nuclear thermo rocket.

Solid core NTRs also may have some level of flexibility as well you could in theory make one able to use CO2 or water for example. 

A VASIMR engine depending on it's design also could have some level of flexibility.
I was talking about first stage stuff only. VASIMIR is not first stage capable.
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