Author Topic: XCOR and the Lynx rocket  (Read 610742 times)

Offline Lar

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Re: XCOR and the Lynx rocket
« Reply #380 on: 03/28/2013 04:18 pm »
New Research Platform to Fly on XCOR Lynx Space Plane

Lynx Cub Payload Carrier Being Developed at Texas A&M
College Station, Texas (Mar. 28, 2013) – A new payload carrier promises to dramatically reduce the cost of access to space for small scientific and education payloads.

 (snip)

http://www.newspacewatch.com/articles/new-research-platform-developed-for-xcor-lynx-space-plane.html

For "getaway special" class experiments that aren't completely passive, is there some standard activation mechanism expected? Suppose, for example, that your experiment requires reagents to be added just before flight. Is it up to you to provide this via some electromechanical means?  Or can you rely on someone to do it for you? And if electrocmechanical, are there standard voltages or signals?

I bet this sort of thing is talked about in payload integration handbooks provided by the various launch providers but are there standards to allow for easy interchange?
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Offline baldusi

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Re: XCOR and the Lynx rocket
« Reply #381 on: 03/28/2013 04:26 pm »
Lurker: liquids do not change volume significantly when under pressure.

But Oxygen and Hydrogen must be pressurized in order to change from gas to liquid form, correct ? Maybe a low thrust engine isn't interested in pushing as much fuel and oxidizer into the combustion chamber as possible, and most of XCORs engines look to be in a small thrust class.
Nope. They cool them. That's why they are called cryogenic (meaning ultra cold). In fact, the whole issue of thermal protection for H2 tanks is because H2 is liquid at about 20K while LOX needs "just" 90K. Whatever excess heat you get the liquid goes liquid, and in the phase change takes away that extra heat. What you'll have is a slight "vapor pressure".
Normal cryogenic liquids are handled, in fact, on open vessels. That allow the gases to get out and thus avoid pressure build up.
In the LV tanks case, you need some pressure. If you have a pressure fed design, you'd need a fraction more than your chamber pressure. Which might be as much as 10bar. Very impractical for big tanks. In the case of pump fed, you just need enough pressure to avoid cavitation on your feedlines. I think less than 3bars are needed, but, for example, Falcon 9 uses a bit more, like 3.4Bar or so.
Please remember that in the XCOR case, the fuel is kerosene, and they only use cryo fro the oxidizer (LOX). But in both cases they need to pressurize them just enough to feed the pumps. After that, the piston pumps do their work to up the pressure to chamber level. Again, as we are talking liquids here, the volume is, practically, the same.
The only case where you use it in gaseous state, is when you use a gas generator to mode a turbine or, probably, after they burn a bit on the low pressure side of the pistons. Normally, designs like Gas Generator rockets, dump that gas after passing it through the turbines. But cycles like the RL10 or the Staged Combustion rockets (RD-25, RD-170/180, etc.) convert all the mass of either the fuel or the oxidizer to gas and actually feed it in gas state. Thus, the Russian nomenclature of calling the staged combustion rockets gas-liquid.

Offline deltaV

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Re: XCOR and the Lynx rocket
« Reply #382 on: 03/28/2013 05:18 pm »
Lurker: I suggest you read up on triple points, vapor pressure, and phase diagrams. Liquid oxygen and liquid hydrogen are not possible in a true vacuum, but the minimum pressure required is much less than an atmosphere (and also much less than typical tank pressures): http://en.wikipedia.org/wiki/Triple_point#Table_of_triple_points .
« Last Edit: 03/28/2013 05:26 pm by deltaV »

Offline krytek

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Re: XCOR and the Lynx rocket
« Reply #383 on: 03/31/2013 04:27 pm »
Just saw this awesome interview at
http://www.newspacewatch.com/articles/interview-with-xcor039s-andrew-nelson-on-spacevidcast.html

At appears We'll be seeing Lynx fly in 2013.
Claimed piston pumps work measured in thousands of hours vs minutes for turbo pumps.
Also claimed figure of piston pump cost up to couple hundred thousand dollars, versus up to a couple of million for turbo pumps.


Offline vulture4

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Re: XCOR and the Lynx rocket
« Reply #384 on: 03/31/2013 08:20 pm »
The piston pump is ingenious and allows high chamber pressure in a small engine, but I would guess it would be much too heavy if scaled up for a large engine like the Merlin.

Offline gin455res

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Re: XCOR and the Lynx rocket
« Reply #385 on: 03/31/2013 11:49 pm »
This press release, claims that these piston pumps are 'game-changing'.

Why is that?
Re-read the quote from Jeff Greason.  Takes away the need for (heavy) high-pressure tanks...     Also, IIRC, when they had the release related to the testing on the motorcycle, they couldn't figure out what a wear mechanism would be.


Looking forward to a vast future for XCOR!  Well done.

I don't understand taking away the need for "high-pressure" tanks. You want to carry as much fuel in as little volume as possible, right ? Doesn't that pretty much guarantee that your fuel will be condensed / pressurized as much as possible ? Sure, you may not need to maintain that pressure over the life of the stage, but I would think high-pressure  (and tanks able to handle that pressure is a given.
hi lurker steve

as i understand it, rocket engines need fairly high pressures to operate efficiently (particularly at atmospheric pressure). These pressures are much higher than those required to keep cryogenic propellants in a liquid state.  These pressures can be achieved either with a pump, or by pressurising the fuel and oxidiser tanks. Pressurising the tanks means they need to be much stronger and this equates to far heavier tanks. Heavy tanks means less payload. So pumps add the weight of the pump, but reduce the weight  of the tanks -  a lot!

Offline krytek

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Re: XCOR and the Lynx rocket
« Reply #386 on: 04/01/2013 01:14 pm »
Any idea what drives Xcor's piston pumps?
In a turbo pump it is the turbine that drives the pump. I was thinking that in a rocket engine piston pump you'd still need a turbine to drive the crankshaft. That is unless there is other mechanism I'm not familiar with.

Offline Robotbeat

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Re: XCOR and the Lynx rocket
« Reply #387 on: 04/01/2013 01:58 pm »
Any idea what drives Xcor's piston pumps?
In a turbo pump it is the turbine that drives the pump. I was thinking that in a rocket engine piston pump you'd still need a turbine to drive the crankshaft. That is unless there is other mechanism I'm not familiar with.
Pistons drive the piston pump (like a car engine). The gas to drive that I think comes from a gas generator, but they apparently have some secret sauce there.
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Offline baldusi

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Re: XCOR and the Lynx rocket
« Reply #388 on: 04/01/2013 06:23 pm »
Any idea what drives Xcor's piston pumps?
In a turbo pump it is the turbine that drives the pump. I was thinking that in a rocket engine piston pump you'd still need a turbine to drive the crankshaft. That is unless there is other mechanism I'm not familiar with.
Pistons drive the piston pump (like a car engine). The gas to drive that I think comes from a gas generator, but they apparently have some secret sauce there.
Couldn't it be that they actually have a spark there? With a little thermal exchange you can have plenty of gas and use standard pistons.

Offline Robotbeat

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Re: XCOR and the Lynx rocket
« Reply #389 on: 04/01/2013 07:46 pm »
Any idea what drives Xcor's piston pumps?
In a turbo pump it is the turbine that drives the pump. I was thinking that in a rocket engine piston pump you'd still need a turbine to drive the crankshaft. That is unless there is other mechanism I'm not familiar with.
Pistons drive the piston pump (like a car engine). The gas to drive that I think comes from a gas generator, but they apparently have some secret sauce there.
Couldn't it be that they actually have a spark there? With a little thermal exchange you can have plenty of gas and use standard pistons.
I'm confident it doesn't use a spark.
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Offline Lar

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Re: XCOR and the Lynx rocket
« Reply #390 on: 04/01/2013 07:54 pm »
I'm confident it doesn't use a spark.

Right, it's a piston PUMP not a piston ENGINE...
« Last Edit: 04/01/2013 07:54 pm by Lar »
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Offline Comga

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Re: XCOR and the Lynx rocket
« Reply #391 on: 04/01/2013 10:19 pm »
I'm confident it doesn't use a spark.

Right, it's a piston PUMP not a piston ENGINE...

You are correct but....

At the risk of extending speculation even farther away from what XCOR is doing and has stated, that other concept is really interesting.

Imagine a piston or Wankel version of the SpaceX/FastTrac turbo-pump, which has a turbine harvesting the power of fuel and oxidizer combustion to directly power a turbine pumping fuel and oxidizer.  In the speculative system two pistons would be run mechanically off the crank shaft that is driven by a combustion engine.  There would be no conversion of mechanical energy to electricity or some other intermediary to power the compressor pumps. It would get even neater if a Wankel form was used, where the other volumes as the triangular rotor wobbles around the chamber would be used to pump fuel and oxidizer, possibly one per rotor, maybe two.  The axel would just hold the rotor in place and move along the prescribed path, not transmit power.  that would occur through the solid body of the rotor.

What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline JohnFornaro

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Re: XCOR and the Lynx rocket
« Reply #392 on: 04/02/2013 01:44 am »
What could XCOR's patent pending thermodynamic cycle possibly be, and how would that enable their pumps to be as efficient as they claim?

Is that proprietary cycle somehow powering their pumps?

Imagine a piston or Wankel version of the SpaceX/FastTrac turbo-pump, which has a turbine harvesting the power of fuel and oxidizer combustion to directly power a turbine pumping fuel and oxidizer.

Along these lines, but the pictures on the website don't offer any clue that could be "Wankel".  Interesting speculation however.

Something has to provide the rotary power.
Sometimes I just flat out don't get it.

Offline relyon

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Re: XCOR and the Lynx rocket
« Reply #393 on: 04/02/2013 03:29 am »
What could XCOR's patent pending thermodynamic cycle possibly be, and how would that enable their pumps to be as efficient as they claim

See US Patent Application Publication number US8341933 B2.

Bob
Bob

Offline yg1968

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Re: XCOR and the Lynx rocket
« Reply #394 on: 04/13/2013 09:41 pm »
Looks like Stratolaunch-Orbital will have some competition. See text in bold below:

XCOR Aerospace - Jeff Greason

XCOR is as much a creation of Space Access as anything else
All started when he went to the the first one
EZ Rocket got down to $500 per flight
Need reliability before we can do the cool things
Reusability can work if and only if:
1. Capital cost is amortized over lifetime
2. Variable cost per flight is low
Suborbital is strategic
Lynx MECO ~100,000 ft
Glass top spacecraft
Three markets: people, payloads, and upper stages
Every year more and more nanosats
Lynx status: not done yet!
Propulsion wise in great shape
No fixed infrastructure (except ex-Marine Corp bunker)
Did Lynx engine test in partnership with Boeing
20 ms non-hypergol RCS
Avionics connected during engine test
Aerodynamics: done
Underside wing fences (right under fillets), allows for larger dihedral
Used the wind tunnel at Wright-Patterson
Cut away of the structure
Four pumps, four engines, each pair of pumps feeds a pair of engines
Started on airframe 2, which might fly first
Had some lessons learned from first airframe, wanted to try them immediately on second airframe
Buzz in the cockpit
Gear are mostly build, except retracts
Wing vendor change
Nose has been surprisingly difficult structurally
Need to close thermodynamic loop for pump/engine
Test LOX tank
In parallel LH2 pump program
Being paid to learn how to handle LH2 has been useful
Have to really reimagine how to handle LH2 with low infrastructure
Orbital vehicle: conception problems solved
Carrier aircraft plus two rocket stages, second is LH2
Goal is $1 million per person
Relocating to between Midland and Odessa
Low population density and big manufacturing base
Orbital vehicle: Carrier aircraft you can buy, both rocket stages reusable

Market is corporations paying to fly personnel to orbit (like offshore oil rigs)
There is a payload market (that he won't talk about) that is not comm sats
Move is because of California, just can't lease more space
Want the development and manufacturing in separate places
Florida will be serial production location
Looking for analog electronic engineers
« Last Edit: 04/14/2013 01:28 am by yg1968 »

Offline simonbp

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Re: XCOR and the Lynx rocket
« Reply #395 on: 04/14/2013 01:24 am »
To be clear, he meant that he intends XCOR to buy a carrier aircraft, not that they are selling carrier aircraft.

Also, the LH2 adds one shift (6-8 hours) to the turnaround, but helps a lot of other things.

Offline yg1968

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Re: XCOR and the Lynx rocket
« Reply #396 on: 04/14/2013 01:26 am »
To be clear, he meant that he intends XCOR to buy a carrier aircraft, not that they are selling carrier aircraft.

Also, the LH2 adds one shift (6-8 hours) to the turnaround, but helps a lot of other things.

They would buy the carrier aircraft from Sratolaunch, presumably?
« Last Edit: 04/14/2013 01:28 am by yg1968 »

Offline simonbp

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Re: XCOR and the Lynx rocket
« Reply #397 on: 04/14/2013 01:35 am »
Oh, there's no way he is going to be that specific. But if I had to speculate (and it is just that), he means an airliner.

Offline Robotbeat

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Re: XCOR and the Lynx rocket
« Reply #398 on: 04/14/2013 02:19 am »
The most serious RLV effort that no one is talking about.

SpaceX--very credible, testing recovery and reuse with their next flight and a prototype, have already achieved orbit and gone to the space station and back 3 times
Blue Origin--credible, have successful VTVL flights under their belt, consistent and significant funding, a hydrogen engine
XCOR--credible, have tested rocket plane operations successfully, are close to finishing vehicle that can send hundreds of people beyond Karman line for cheap, have innovative reuse and pump technology, laser-focused on high reusability and fast turnaround operations, unknown funding level and stability

And in Europe: Skylon

What a world we live in.
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Offline Robotbeat

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Re: XCOR and the Lynx rocket
« Reply #399 on: 04/14/2013 02:24 am »
"Market is corporations paying to fly personnel to orbit (like offshore oil rigs)"

Can someone paint a picture of this? Is this remotely pointing to a winged Linx-type reusable that can achieve orbit?
yes, and it isn't actually news (though some details may be). They've presented on it before. On their website: http://www.xcor.com/about_us/
« Last Edit: 04/14/2013 02:32 am by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

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