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Bruno Berger | 1 Apr 2003 10:13
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XCOR's new Kerosene Engine

It was quite quiet lately about XCOR. Now they have tested a new 
kerosene engine with 2.5 x higher chamber pressure (still heat sink 
mode though):

http://www.xcor.com/XR4K5-firstfire.html

Do they use pump feed now? At least for the Xerus, pressure feeding 
 <at>  50-60 bar isn't very economical anymore. 

Bruno

--

-- 
Bruno Berger
Swiss Propulsion Laboratory
E-Mail: bruno.berger <at> spl.ch
WWW:    http://www.spl.ch
HAM:    HB9RSU
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Aleta Jackson | 1 Apr 2003 20:37
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Re: XCOR's new Kerosene Engine

Bruno Berger wrote:

>It was quite quiet lately about XCOR. Now they have tested a new 
>kerosene engine with 2.5 x higher chamber pressure (still heat sink 
>mode though):
>
>http://www.xcor.com/XR4K5-firstfire.html
>
>Do they use pump feed now? At least for the Xerus, pressure feeding 
> <at>  50-60 bar isn't very economical anymore. 
>
>Bruno
>
>  
>
Bruno,
We always run our engines in heat sink mode at first. And we continue to 
work on the pump. Build a little, test a lot.

Aleta
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David Weinshenker | 1 Apr 2003 20:55
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Re: XCOR's new Kerosene Engine

Aleta Jackson wrote:
> We always run our engines in heat sink mode at first. And we 
> continue to work on the pump. Build a little, test a lot.

I note that, after extolling the handling convenience of alcohol,
y'all are now going to kerosene? What variety are you using? Can
you get RP-1, or is there a "jet" grade of comparable quality
available these days?

-dave w
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Aleta Jackson | 1 Apr 2003 20:50
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Re: XCOR's new Kerosene Engine

David Weinshenker wrote:

>I note that, after extolling the handling convenience of alcohol,
>y'all are now going to kerosene? What variety are you using? Can
>you get RP-1, or is there a "jet" grade of comparable quality
>available these days?
>
A customer asked that we do this. Aleta
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Henry Spencer | 1 Apr 2003 21:18

Re: XCOR's new Kerosene Engine

On Tue, 1 Apr 2003, David Weinshenker wrote:
> I note that, after extolling the handling convenience of alcohol,
> y'all are now going to kerosene? What variety are you using? Can
> you get RP-1, or is there a "jet" grade of comparable quality
> available these days?

If you cool with the oxidizer instead of the fuel, and avoid using a
fuel-rich gas generator for pump drive, RP-1 has no particular advantages
to make up for its high price and limited availability.  If all you're
going to do is inject it into the chamber, ordinary jet fuel does just
fine as a rocket fuel. 

There are scary superstitions about oxidizer cooling, but in fact it works
just fine, and the ex-Rotary-Rocket folks on the XCOR team have previous
experience with it.  It does add some design constraints, e.g. with LOX
you almost certainly need pumps (because LOX's liquid range is fairly
narrow unless you're above its critical pressure, which is sizable). 

As for pump drive, one approach is to run the gas generator's burner at a
balanced mixture ratio, and use water injection to cool the gas down
enough to be compatible with the pump materials.  (Arianes 1-4 did this.)

There are commercial hydrocarbon mixes that might be as good as RP-1 at
resisting polymerization and coking, e.g. USP Mineral Oil, but I don't
know that anybody's really explored them. 

As to why they did it, the obvious reason is that somebody who was putting
up money for development work had a preference for it.  In business,
unless you're really doing well and have more work than you can handle,
when somebody wants to pay you to do something you're not keen on, the
(Continue reading)

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Henry Spencer | 1 Apr 2003 21:22

Re: XCOR's new Kerosene Engine

On Tue, 1 Apr 2003, Aleta Jackson wrote:
> We always run our engines in heat sink mode at first.

As do almost all pro rocket-engine builders.  That lets you check out the
injector and the combustion behavior before worrying about cooling. 

                                                          Henry Spencer
                                                       henry <at> spsystems.net
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Bruno Berger | 1 Apr 2003 21:58
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Re: XCOR's new Kerosene Engine

Aleta Jackson wrote:
 > Bruno Berger wrote:
 >
 >> It was quite quiet lately about XCOR. Now they have tested a new
 >> kerosene engine with 2.5 x higher chamber pressure (still heat sink
 >> mode though):
 >>
 >> http://www.xcor.com/XR4K5-firstfire.html
 >>
 >> Do they use pump feed now? At least for the Xerus, pressure feeding  <at> 
 >> 50-60 bar isn't very economical anymore.
 >> Bruno
 >>
 >>
 >>
 > Bruno,
 > We always run our engines in heat sink mode at first. And we continue to
 > work on the pump. Build a little, test a lot.
 >
 > Aleta

Sure, we are also doing this first. The "though" wasn't meant to belittle
your approach, far from it :-)
A heat sink engine gives you enough time (1 to several seconds) to test
everyting, specially the ingition sequence. Ours were also very heavy walled
to survive any hardstarts (would be a pitty to loose our nice liners with
the milled cooling channels).
About the pump... we have choosen to go the turbopump way. The project
starts with a radial inflow turbine derived from a automotive turbo charger.
The gas generator already works quite fine. Next step will be a test bench
(Continue reading)

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David Weinshenker | 2 Apr 2003 03:07
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Re: Minutes of ERPS #256

Randall Clague wrote:
> 
> On Wed, 26 Mar 2003 19:31:09 -0800, David Weinshenker
> <daze39 <at> earthlink.net> wrote:
> 
> > *Left Coast Rocketry is an independent association dedicated to
> > promoting the safe sport of amateur rocketry in all of its legal
> > manifestations. It is not associated with Tripoli Rocketry Association
> > or the National Association of Rocketry. *******************
> 
> I'll be interested in hearing about their launch facilities - if they
> satisfy CSFM rules for liquid fuel rockets, Petaluma is a lot closer than
> Mojave...

Sean and I went last weekend... the field (the old Liberty Airfield near Petaluma)
is more like the one the Sacramento club had than the setup at Mojave... experimental 
support is relatively limited at this point (no class I pyro op support for liquids) 
but there were some home-cast solids as well as commercial motors launched.

They're not really a substitute for PRS - more like an "unaffiliated" alternative
to Livermore, Sacramento, etc. Nice folks, fun launch. Next events are tentatively 
planned for July and October this year.

-dave w
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Thomas J. Williams | 2 Apr 2003 06:18

FYI - Aviation Week Aerospike article

FYI - The 3/31/03 edition of Aviation Week (pg 18) has a 1/2 page article
about "JP Rocket Engines" of Salt Lake City flying a ~200 lb (thrust)
Aerospike engine on March 15.  They flew a Dynamics Composites Inc.
"Scorpion" to 3413 ft. AGL  It was a 5 hole stainless steel nozzle made to
fit a commercial Aerotech rocket motor.

-Tom Williams
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David Weinshenker | 2 Apr 2003 09:57
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Re: XCOR's new Kerosene Engine

Henry Spencer wrote:
> As for pump drive, one approach is to run the gas generator's burner at a
> balanced mixture ratio, and use water injection to cool the gas down
> enough to be compatible with the pump materials.  (Arianes 1-4 did this.)

And then there's what the Russians did in the RD-170 etc.: run all the oxygen 
and a little bit of the fuel in a low-temperature oxygen-rich pre-burner, 
heating the oxygen enough to boil it and spin the pump turbine before combining 
it in the chamber with the rest of the fuel. (Just the opposite of the SSME, 
with its fuel-rich preburner... and since it's denser, pumping all the oxygen up 
to the preburner inlet pressure costs less in pump power than doing that to all 
the hydrogen fuel in the SSME...)

Air-breathing turbojets have always used "oxidizer cooling", 
so it's not like there wasn't a precedent...

-dave w
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