Author Topic: Two stage, Vertical takeoff, Chemical rocket (fully) RLV  (Read 18320 times)

Offline KelvinZero

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This strikes me as about the most conservative approach to reusable lift vehicles.

I would like to see a RLV discussion dedicated just to this. It is ok to generalize two stage to 1.5 stage, and I havent specified whether landing is parachutes, rockets, wings or something else.

What actually are the difficulties that prevent us having one right now? Is anyone close to being able to make this work?
« Last Edit: 03/11/2010 08:29 am by KelvinZero »

Offline ChrisSpaceCH

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #1 on: 03/11/2010 08:27 am »
Musk is aiming for this in a future iteration of the Falcon 9. I don't have any specifics, though. Any further info would be appreciated.

Offline KelvinZero

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« Last Edit: 03/12/2010 08:40 am by KelvinZero »

Offline William Barton

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #3 on: 03/11/2010 11:17 am »
This strikes me as about the most conservative approach to reusable lift vehicles.

I would like to see a RLV discussion dedicated just to this. It is ok to generalize two stage to 1.5 stage, and I havent specified whether landing is parachutes, rockets, wings or something else.

What actually are the difficulties that prevent us having one right now? Is anyone close to being able to make this work?

The Kistler K-1 was a good example of a way it could work. TSTO, first stage RTLS recovery with parachutes and airbags, second stage thermal protected reentry to launch site recovery with parachutes and airbags. What prevengted it from working (unresolved technical questions aside) was lack of money.

Offline kkattula

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #4 on: 03/11/2010 11:46 am »
It's one of my favorite approaches.

I'd add Vertical Landing for the first stage. This could be down-range, since most launches are to only one or two distinct orbital inclinations from a given launch site.

This approach also lends itself to starting with an ELV second stage, and progressing to an RLV in due course.

Offline mboeller

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #5 on: 03/11/2010 12:11 pm »
a few ideas and concepts:

http://mikesnead.net/resources-spacefaring.htm

One of these concepts is a two stage RLV but at the moment I'm unable to give you the correct link to the specific PDF.


Offline Propforce

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #6 on: 03/11/2010 03:05 pm »
Why not a 3 stage RLV?

Offline neilh

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #7 on: 03/11/2010 04:49 pm »
Why not a 3 stage RLV?

Out of curiosity, where is that image from?
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Offline Propforce

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #8 on: 03/12/2010 05:29 am »
Why not a 3 stage RLV?

Out of curiosity, where is that image from?

Look at the logo on the vehicles.

Offline KelvinZero

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #9 on: 03/12/2010 08:46 am »
The Kistler K-1 was a good example of a way it could work. TSTO, first stage RTLS recovery with parachutes and airbags, second stage thermal protected reentry to launch site recovery with parachutes and airbags. What prevengted it from working (unresolved technical questions aside) was lack of money.
Thanks! I edited in a link higher up.

Offline KelvinZero

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #10 on: 03/12/2010 09:11 am »
It's one of my favorite approaches.

I'd add Vertical Landing for the first stage. This could be down-range, since most launches are to only one or two distinct orbital inclinations from a given launch site.

This approach also lends itself to starting with an ELV second stage, and progressing to an RLV in due course.

I remember someone here claiming quite a small additional weight in fuel for a vertical landing.. Anyone able to support that?

Evolving from an expendable tsto to a reusable tsto also seems an interesting topic. What design choices in the expendable would let you consider either evolving the 1st stage to reusable and/or evolving/replacing the second stage?

Offline KelvinZero

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #11 on: 03/12/2010 09:25 am »
Why not a 3 stage RLV?

Because it's funny lookin' ?  :)

Actually I dont know if that is an important limitation but I was assuming something more conventional looking.. probably because I have also been wondering about evolving an RLV from a conventional TSTO, as I guess is implied by spaceX

Offline kkattula

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #12 on: 03/12/2010 11:15 am »
I remember someone here claiming quite a small additional weight in fuel for a vertical landing.. Anyone able to support that?

Probably me.  It's fairly easy to work out from the rocket equation. Assuming:

a) The stage has slowed to around 100 m/s by the time it nears sea level, which it should, it's fluffy enough when empty.

b) That one or more of the launch engines can re-lit, so no extra engine mass

Then it just needs sufficient fuel to decel (say 10 seconds @ 2 g = 196 m/s ) plus say 5 seconds of 1 g hover/final descent (49 m/s). Less than 250 m/s total.  If you think that's not enough, check out Armadillo's boosted hops.

For Isp 250, that's 10.7% of dry mass. Plus you need legs and some TPS. So 15% to 20% mass penalty seems plenty. That's only for the first stage. The effect on second stage payload is likely only 2% to 3%. Just make the whole design slightly larger to negate that.

« Last Edit: 03/12/2010 11:18 am by kkattula »

Offline kkattula

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #13 on: 03/12/2010 11:28 am »
.

Evolving from an expendable tsto to a reusable tsto also seems an interesting topic. What design choices in the expendable would let you consider either evolving the 1st stage to reusable and/or evolving/replacing the second stage?

I wouldn't evolve the first stage. Starting as a VTVL RLV allows incremental testing, gradual expansion of the envelope, with ONE test LV. Plus possible early revenue for sub-orbital payloads.

I might consider starting with an expendable second stage and a reusable payload carrier/spacecraft, that performs orbital insertion and possibly acts as a small third stage.  This could allow the second stage to be very simple and inexpensive. Just a tank and a low pressure engine. That might be cheaper to expend than flying an RLV.

Offline William Barton

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #14 on: 03/12/2010 11:36 am »
Why not a 3 stage RLV?

At one point, a "trimaran" concept was proposed for the space shuttle, consiting of three "orbiters" sandwiched together, with the two outer ones acting as boosters for the inner one, which would proceed to orbit. I googled for an image, but nothing bubbled close to the surface. Too many seagoing trimarans in the world. The only picture I have is in one of Phil Bono's old books (still in storage).
« Last Edit: 03/12/2010 11:36 am by William Barton »

Offline sewand

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #15 on: 03/12/2010 11:41 am »
Why not a 3 stage RLV?

At one point, a "trimaran" concept was proposed for the space shuttle, consiting of three "orbiters" sandwiched together, with the two outer ones acting as boosters for the inner one, which would proceed to orbit. I googled for an image, but nothing bubbled close to the surface. Too many seagoing trimarans in the world. The only picture I have is in one of Phil Bono's old books (still in storage).

Sounds like a British concept called Mustard. (I have the same Bono book)

http://www.astronautix.com/lvs/mustard.htm

Offline JPK

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #16 on: 03/12/2010 11:44 am »
Try MUSTARD - Multi-Unit Space Transport And Recovery Device:-

www.astronautix.com/lvs/mustard.htm
and
en.wikipedia.org/wiki/MUSTARD

Offline William Barton

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #17 on: 03/12/2010 12:03 pm »
Why not a 3 stage RLV?

At one point, a "trimaran" concept was proposed for the space shuttle, consiting of three "orbiters" sandwiched together, with the two outer ones acting as boosters for the inner one, which would proceed to orbit. I googled for an image, but nothing bubbled close to the surface. Too many seagoing trimarans in the world. The only picture I have is in one of Phil Bono's old books (still in storage).

Sounds like a British concept called Mustard. (I have the same Bono book)

http://www.astronautix.com/lvs/mustard.htm

That's the one, I just couldn't remember the name (my books will be in storage for about another 4 months; I'll be very happy to have them back!). Apparently, there's an Australian boat company with the initials BAE that makes trimarans...

Offline sewand

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #18 on: 03/12/2010 12:21 pm »

That's the one, I just couldn't remember the name (my books will be in storage for about another 4 months; I'll be very happy to have them back!). Apparently, there's an Australian boat company with the initials BAE that makes trimarans...

I've had his Frontiers of Space book since I was a kid.  I still think a Pegasus/Icarus intercontinental suborbital transport is where the money is at!    :-)

Offline Propforce

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #19 on: 03/12/2010 05:47 pm »
Why not a 3 stage RLV?

At one point, a "trimaran" concept was proposed for the space shuttle, consiting of three "orbiters" sandwiched together, with the two outer ones acting as boosters for the inner one, which would proceed to orbit. I googled for an image, but nothing bubbled close to the surface. Too many seagoing trimarans in the world. The only picture I have is in one of Phil Bono's old books (still in storage).

Here's a picture of Space Shuttle design "evolution".  The left one is the first stage flyback booster, the middle one appears to be a 3 stage but only the orbital is a reusable, and the right one is what we have now.


Offline Robotbeat

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #20 on: 03/12/2010 06:58 pm »
I wonder if that first one is doable.
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Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #21 on: 03/12/2010 07:11 pm »
Why not a 3 stage RLV?

At one point, a "trimaran" concept was proposed for the space shuttle, consiting of three "orbiters" sandwiched together, with the two outer ones acting as boosters for the inner one, which would proceed to orbit. I googled for an image, but nothing bubbled close to the surface. Too many seagoing trimarans in the world. The only picture I have is in one of Phil Bono's old books (still in storage).

Ah dont use the trimaran term, as I recall it was one of the Shuttle design options way back.

http://www.astronautix.com/graphics/s/shutbmm1.jpg
This was a Martin Marietta design. Also known as "Spacemaster"
http://www.astronautix.com/lvs/spaaster.htm

There was also the Shuttle LRB 1989 design for liquid reusable boosters:
http://www.astronautix.com/graphics/y/yshl4b98.jpg

Here's some MUSTARD images:
http://nmg.livejournal.com/123811.html
« Last Edit: 03/12/2010 07:14 pm by mlorrey »
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Offline edkyle99

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #22 on: 03/12/2010 08:00 pm »

Here's a picture of Space Shuttle design "evolution".   ....  the middle one appears to be a 3 stage but only the orbital is a reusable ...

I think the middle concept consisted of an S-IC based first stage topped by an air-start orbiter attached to an external tank.

 - Ed Kyle

Offline indaco

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #23 on: 03/13/2010 01:27 am »
This strikes me as about the most conservative approach to reusable lift vehicles.

I would like to see a RLV discussion dedicated just to this. It is ok to generalize two stage to 1.5 stage, and I havent specified whether landing is parachutes, rockets, wings or something else.

What actually are the difficulties that prevent us having one right now? Is anyone close to being able to make this work?

The Kistler K-1 was a good example of a way it could work. TSTO, first stage RTLS recovery with parachutes and airbags, second stage thermal protected reentry to launch site recovery with parachutes and airbags. What prevengted it from working (unresolved technical questions aside) was lack of money.

Trying to guess the concept (correct me if I'm wrong).

The first stage phase is relatively short and pretty vertical.

This way the first stage reentry is not too harsh, and very close to the launch base, allowing relativeliy wide design margins (in term of isp and total mass) and termal shielding. It has just to kick the second stage out of the atmosphere giving it a little of speed. The first stage doesn't require so much cross-range capability and returning home immediatly in principle can have a very short turnaround time.

This way, apparently, most of the delta V is provided by the second stage.

But still the second stage is much more workable than a SSTO.   

First of all it can use engines optimized for void.

Second, even a low vertical speed provided by the assist of the first stage reduce dramatically gravity losses allowing a lower thrust/weight ratio compared to a SSTO.

Lower thrust allows a smaller engine for the same tank, or a bigger tank for the same engine.... in other words a better mass ratio.

If this doesn't suffice to achieve orbit with a decent payload (but it's seems it does for Kistler), maybe it's possible to jettison fairing after separation from the first stage (or the fairing could be part of the first stage and so reusable... in other words the 2nd stage comes out from a cargo bay......interesting but it could be complicated).

Even better, if we could renunce a little of reusability using an expendable external tank for the second stage (I suppose a tank for RP1-LOX could be relatively simple, cheap and mass produced....after all an expendable packaging could even improve some economics, my trash is full of expendable pressurized allumium tanks used to store, deliver and handle various spray products and this is pretty efficient for the industry).

As the second stage complete at least an orbit, it also could return exactly to home in a relative short time allowing a short turnaround time, like for the first stage.

So, maybe this mission profile with a short and vertical 1° stage phase allows reusability and high usage factor for both the stages, at expense (probably) of a suboptimal payload compared to a more traditional TSTO with a better optimized trajectory.

Of course all the above is guessed. :)
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Offline KelvinZero

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #24 on: 03/13/2010 01:33 am »

I wouldn't evolve the first stage. Starting as a VTVL RLV allows incremental testing, gradual expansion of the envelope, with ONE test LV. Plus possible early revenue for sub-orbital payloads.

I might consider starting with an expendable second stage and a reusable payload carrier/spacecraft, that performs orbital insertion and possibly acts as a small third stage.  This could allow the second stage to be very simple and inexpensive. Just a tank and a low pressure engine. That might be cheaper to expend than flying an RLV.


I can see how a reusable first stage could find many different uses immediately. Im also guessing reusable vertical landing first stage is less technically difficult than a reusable stage that has to survive reentry. On the other hand the non reusable stages already exist or are on the way, For example SpaceX seems to be taking this approach.

Two reasons I can see for starting from the top down are that being smaller, you might be able to go through iterations faster, and if it is manned you already have the requirement of bringing at least something down intact from orbital velocity.

However these are just my uninformed guesses. Perhaps what would be more promising is that either and both options could be open to you: reusable 1st stage, reusable 2nd stage or both according to future requirements.

Offline Propforce

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #25 on: 03/13/2010 02:38 am »

Here's a picture of Space Shuttle design "evolution".   ....  the middle one appears to be a 3 stage but only the orbital is a reusable ...

I think the middle concept consisted of an S-IC based first stage topped by an air-start orbiter attached to an external tank.

 - Ed Kyle

It sure looks like a S-IC doens't it?  I just can't see from this angle if that's a 2nd stage or a strap-on tank.

Thanks.


Offline edkyle99

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #26 on: 03/13/2010 03:21 am »

Here's a picture of Space Shuttle design "evolution".   ....  the middle one appears to be a 3 stage but only the orbital is a reusable ...

I think the middle concept consisted of an S-IC based first stage topped by an air-start orbiter attached to an external tank.

 - Ed Kyle

It sure looks like a S-IC doens't it?  I just can't see from this angle if that's a 2nd stage or a strap-on tank.

Thanks.

There was an S-IC based design, but, after looking at this photo a bit more, I now think this one is showing a Grumman/Boeing design that called for a new pump-fed booster with seven F-1 class engines.  There were other designs too.  Some used monster 260 inch diameter solid motors.  Some called for a big pressure fed booster.  One used a Titan III core with six Titan III strap on boosters!

 - Ed Kyle 
« Last Edit: 03/13/2010 03:22 am by edkyle99 »

Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #27 on: 03/13/2010 05:28 pm »
The big question is how is a launch vehicle reused? Personally I never saw the point in reusing a fuel tank. They're relatively cheap to make (shuttle ET, according to studies I've seen costs less than a million bucks when you discount all the administrative overhead) and make for good useful pressurized space in orbit. I'd like to bring up my old ET derived 1.5STO family of HLVs.
« Last Edit: 03/13/2010 05:39 pm by mlorrey »
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Offline Cog_in_the_machine

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #28 on: 03/13/2010 05:37 pm »
Holy ....

I like the last one :)
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Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #29 on: 03/13/2010 05:40 pm »
Holy ....

I like the last one :)

Yes, that last one is to make the girls gird their loins...
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Offline Cog_in_the_machine

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #30 on: 03/13/2010 05:44 pm »
Yes, that last one is to make the girls gird their loins...

Would probably have a big base heating problem though.
« Last Edit: 03/13/2010 05:45 pm by Cog_in_the_machine »
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Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #31 on: 03/13/2010 05:46 pm »

Yes, that last one is to make the girls gird their loins...

Would probably have a big base heating problem though.

Significantly less than the ET already deals with from the SRBs. Or did you mean the girls?
« Last Edit: 03/13/2010 05:46 pm by mlorrey »
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Offline Cog_in_the_machine

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #32 on: 03/13/2010 05:49 pm »
The launcher. And idk, I think one of the concerns with the Direct launchers was base heating, and they have just one ET core. That thing has 7 (I think).
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Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #33 on: 03/13/2010 05:57 pm »
The launcher. And idk, I think one of the concerns with the Direct launchers was base heating, and they have just one ET core. That thing has 7 (I think).

Yeah it does. The main difference between this and Direct is that Direct hangs on to all the engines all the way to orbit, this one drops all but one sustainer for each core when its 3/4 there. This should mitigate the peak base heating that should happen at altitude. Thus, 1.5 stages, and greater payload capacity per core.
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Offline kkattula

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #34 on: 03/14/2010 05:50 am »
Slight problem, more than a 3 core version couldn't be launched at KSC. Obviously even a 3 core would need a massive pad upgrade, but there is a limit to the total amount of lift-off thrust before acoustic damage to the surrounding areas is too great.  That limit is about 12 million lbf.


Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #35 on: 03/14/2010 06:16 pm »
Slight problem, more than a 3 core version couldn't be launched at KSC. Obviously even a 3 core would need a massive pad upgrade, but there is a limit to the total amount of lift-off thrust before acoustic damage to the surrounding areas is too great.  That limit is about 12 million lbf.

How do you equate thrust to noise and isn't that at all dependent upon the engines? Are there existing maps with acoustic footprints available online?

The base size correlates with plans for the Nova pads as well as for the SPS launchers that Boeing designed in the late 70's.
« Last Edit: 03/14/2010 06:19 pm by mlorrey »
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Offline gospacex

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #36 on: 03/14/2010 07:27 pm »
The big question is how is a launch vehicle reused? Personally I never saw the point in reusing a fuel tank. They're relatively cheap to make (shuttle ET, according to studies I've seen costs less than a million bucks when you discount all the administrative overhead) and make for good useful pressurized space in orbit. I'd like to bring up my old ET derived 1.5STO family of HLVs.

Too big (in geometric sense). LH in 1st stage is not the best idea.

Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #37 on: 03/14/2010 08:00 pm »
The big question is how is a launch vehicle reused? Personally I never saw the point in reusing a fuel tank. They're relatively cheap to make (shuttle ET, according to studies I've seen costs less than a million bucks when you discount all the administrative overhead) and make for good useful pressurized space in orbit. I'd like to bring up my old ET derived 1.5STO family of HLVs.

Too big (in geometric sense). LH in 1st stage is not the best idea.

Well, 1.5STO is going to use the same fuel on the .5 boost and the 1st stage sustainer motor, unless you want to get hopelessly complex with multiple fuels. I am normally a critic of hydrogen fuelled launch vehicles, though, particularly due to tank size/mass and cryogenic requirements. This launch vehicle family I envisioned is IMHO really the only way to use LH advantageously in as few stages as possible.

Another idea I had was to treat the LOX tank of the Shuttle ET as a crew compartment/cargo bay, and divide the hydrogen tank into a lox tank and a hydrocarbon tank. Use the same 1.5 stage boost pod/sustainer but using kerolox engines.

Third idea was to reduce the size of the LOX tank to half its current size, have the 0.5 boost pod with five SSME engines in a ring around a central nuclear sustainer engine that would not light until it reached 100k ft. Once in orbit, the LOX tank would be convertible into living space and suddenly you've got a great interplanetary spaceship.... launch with a 1000 sec nuclear sustainer motor would leave 1/4 of the hydrogen fuel for use in space.

A tanker model should be able to fully refuel the interplanetary model in one launch.
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Offline indaco

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #38 on: 03/15/2010 12:02 pm »
Well, 1.5STO is going to use the same fuel on the .5 boost and the 1st stage sustainer motor, unless you want to get hopelessly complex with multiple fuels. I am normally a critic of hydrogen fuelled launch vehicles, though, particularly due to tank size/mass and cryogenic requirements. This launch vehicle family I envisioned is IMHO really the only way to use LH advantageously in as few stages as possible
.....

What about the MAKS approach?

A tri-propellant engine seems very attractive.

I think this is the thing that has arrived more close to a mostly reusable 1.5 stages.  Stage 0 exists, the An-225 Mriya carrier aircraft has been developed for this scope.

If a tri-propellant engine like RD-701 will work as stated (ie. thust/mass good as a pure RP1, isp good as a pure LH2) it could really change things.

During the boost phase you use a dense fuel, so you have the required thrust/mass.

For the sustain phase you switch to cryogenic fuel, reusing most of the  same engine parts (bell, combustion chamber, some turbines, gimbaling etc.)... this saves a lot of mass compared to having specialized engines for different phases.

The performances declared for MAKS are very good, it seems relatively close to be flown, developing apparently stopped just for funding reasons and reausability is almost complete, except for external tank.

But I repeat that tank is just "packaging" and on the other hand it simply seems unworkable to reentry and reuse a tank having the volume required so we must expende it, at least with chemical engines.

By the way, remembering about MAKS I changed my mind about variable isp engine for a launcher.   I cross quote from the 3d about RLV:

I repeat I can't see a reason for variable isp.

Even for SSTO, varying the Isp (and being able to airbreathe for a good chunk of the ascent) can be very helpful to optimize the vehicle's efficiency.

RD-701 is exactly a variable isp chemical engine....I don't know if it exists, but the Russians must be taken seriously for space veichles.
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Offline Robotbeat

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #39 on: 03/15/2010 03:27 pm »
Wow, just reading about the RD-701. The more I read about the Russian/Soviet space program, the more respect I have for them.
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Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #40 on: 03/15/2010 06:43 pm »
Wow, just reading about the RD-701. The more I read about the Russian/Soviet space program, the more respect I have for them.

Russians always had great mechanical, chemical and aerospace engineers. It was the industrial and IT engineering, as well as dumb marxist management that always held them back.

I like the MAKS system, though it is payload limited and doesn't scale to HLV. It definitely deserves more capital invested in it.

That said, while I like the variable Isp capability, the plumbing complexity tells me that maintenance between flights would be high, because you essentially have double the amount of plumbing and turbomachinery to take care of.

Beyond easy TPS maintenance, low maintenance engines are the second ingredient to  an economical RLV.
« Last Edit: 03/15/2010 06:46 pm by mlorrey »
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Offline indaco

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #41 on: 03/15/2010 07:45 pm »
... It definitely deserves more capital invested in it.
...

Maybe the tri-propellant concept deserves a little of study and investment in the west, also.
 
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Offline indaco

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #42 on: 03/15/2010 08:06 pm »
...
Beyond easy TPS maintenance, low maintenance engines are the second ingredient to  an economical RLV.

About this, on the Pratt&Whitney Rocketdyne site they declare that the RL10 derived CECE will have a service life of 10000 seconds and 50 restarts.

I'm not certain I've understand, but if it was 10000 secs without servicing, this could be enough for about 15-20 launchs.

Expander cycle turbines work at low temperature, and this helps a lot.

Of course a 100% LH2 require a very big tank, and it's difficult to make cheap and to carry on a jet carrier....  So the problem of stage 0 is still open.... a fly back booster of some other mean is required.
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Offline RanulfC

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #43 on: 03/16/2010 04:59 pm »
mlorry:
The problem with using the ETs on-orbit is they are flimsy, especially the latest "light-weight" tanks. Other than the hard-backs for mounting the SRBs and Orbiter they are chemically etched iso-grids so thin in places a good kick or punch will rip right through the metal. (Especially on-orbit if they were pressurized)

It's one of the main reasons that doing an "in-line" booster is going to take some major redesign work. Actually what we NEED to do is go back to the "heavy-weight" tank design with the lighter alloys since most of the "usable" ET work was done with that design.

Tri-Propellant engines:
Check out Robert Salkeld, mixed-mode rocket engines, and Tripropellant in google :)
The west HAS done a great deal of work on the concept including test firings. (Using a modified RL-10 IIRC but I could be mistaken)
http://www.pmview.com/spaceodysseytwo/spacelvs/sld039.htm

On the RL-10 yes that number means 1000 seconds (a little over 16 minutes) of fireing without maintenance. (Though it should be noted that COULD be reused it is however not DESIGNED to be reused so while there have been multiple re-firings of the engine in operation as well as bench testing luck-of-the-draw says you could STILL end up with the one engine that works for 10 seconds and then quits ;) )

Air Launch:
AirLaunch LLC has continued to work on refining the Transformational Space Air Launch concept and has come up with a way for a "Standard" 747-200 to be a carrier vehicle for an orbital launcher:
http://airlaunchllc.com/AIAA-2008-7835-176.pdf

Basically with some $2-million dollars worth of mods to a standard Air-Freighter frame, (mostly tankage and pumping equipment for weight-and-balance during launch but also happens to "double" as arial fire fighting equipment) to carry under-slung a launch vehicle up to 8 feet in diameter. The T-Space orginal TSTO single-barrel 13 foot diameter launch vehicle has been redesigned as a 3STO three-barrel vehicle with the exact same payload to orbit as the original vehicle.

Finally the LH2/RL-10 observation notes the large tank size for LH2, but you don't HAVE to use LH2! The RL-10 has been run using Liquid (Cryogenic or "pre-chilled" as it is sometimes called) Propane with no issues and CLP (Cryogenic Liquid Propane) ends up having the majority of properties equal to LH2 at around 8 times the density! (Around 80% of the ISP for Hydrogen at RP-1 density and tanks sizes!)
As a note the T-Space/AirLaunch booster also uses Liquid Propane but the engines and tankage are all designed to use the VAPaC self-pressurization technology. Trade for increased tank weight and lower engine complexity.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline mlorrey

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #44 on: 03/16/2010 09:50 pm »
mlorry:
The problem with using the ETs on-orbit is they are flimsy, especially the latest "light-weight" tanks. Other than the hard-backs for mounting the SRBs and Orbiter they are chemically etched iso-grids so thin in places a good kick or punch will rip right through the metal. (Especially on-orbit if they were pressurized)

It's one of the main reasons that doing an "in-line" booster is going to take some major redesign work. Actually what we NEED to do is go back to the "heavy-weight" tank design with the lighter alloys since most of the "usable" ET work was done with that design.


Actually I was thinking of utilizing large Polyvinylidene Fluoride bags/tubes to fit around each tank in orbit, with a 0.5 mm wall thickness, this material is a heat shrink polymer that tolerates high temperatures, high ionization levels, and abrasions as well. Density of this material is only 1.48, so its pretty low mass, and would create a good outer structural containment of the foam but also would provide support to the isogrid tank itself.

Also, the tank is built for pressure levels more than twice that of normal sea level pressure (at the top) and significantly more than that at the bottom, so I can't see it as being seriously stressed by being used as habitat space.

PVDF normal operating temps are up to 175 C, which is less than the 145 C peak daytime temps one would see in orbit.
« Last Edit: 03/17/2010 12:51 am by mlorrey »
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Offline RanulfC

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #45 on: 03/18/2010 07:20 pm »
mlorry:
The problem with using the ETs on-orbit is they are flimsy, especially the latest "light-weight" tanks. Other than the hard-backs for mounting the SRBs and Orbiter they are chemically etched iso-grids so thin in places a good kick or punch will rip right through the metal. (Especially on-orbit if they were pressurized)

It's one of the main reasons that doing an "in-line" booster is going to take some major redesign work. Actually what we NEED to do is go back to the "heavy-weight" tank design with the lighter alloys since most of the "usable" ET work was done with that design.


Actually I was thinking of utilizing large Polyvinylidene Fluoride bags/tubes to fit around each tank in orbit, with a 0.5 mm wall thickness, this material is a heat shrink polymer that tolerates high temperatures, high ionization levels, and abrasions as well. Density of this material is only 1.48, so its pretty low mass, and would create a good outer structural containment of the foam but also would provide support to the isogrid tank itself.

Also, the tank is built for pressure levels more than twice that of normal sea level pressure (at the top) and significantly more than that at the bottom, so I can't see it as being seriously stressed by being used as habitat space.

PVDF normal operating temps are up to 175 C, which is less than the 145 C peak daytime temps one would see in orbit.
Hmmm, good one with the cover idea, I hadn't seen that before. As for the tanks themselves "yes" they are 'tough' in the places they need to be but as one engineer put it, "In a Vacuum you could BUMP the right spot and put your hand through it" with internal pressure.

I've wondered about the idea of using Bigelow/TransHab material sucked-down to near vacuum as insulation material for a launch and then inflated in orbit for protection.
On the OTHER hand I've been looking over materials reports on using bamboo fibers in place of carbon fibers (in a composite matrix the values are EXTREMEMLY close) with a binder matrix that breaks down quickly in a VERY high UV flux (like  on-orbit) for expendable propellant tanks.
No mess, no fuss... atoms in the solar wind :o)

My mind tends to wander...

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline indaco1

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #46 on: 03/18/2010 09:41 pm »
If the tank is made of organics it could burn in the upper atmosphere with a relatively low pollution (except if it contains chlorine or other pollutants).

But, as volatiles could be precious in space, I'm going to say something extremely stupid.

What about the possibility of using expended tanks as raw material or even fuel?

Eg. I've not idea of mechanical properties of polyethylene at cryogenic temperatures but, as it's made just of (-C2H4-)n, maybe it could be melted and used as rocket propellant itself. Maybe other polimeres can be used in this way or dissolved with another solvent propellant. Most of solvents are good as fuel.

This way you eat the plate, also..  and nothing is wasted.

I told you it was stupid, I know it's not realistic in the short term :)
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Offline KelvinZero

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #47 on: 03/19/2010 05:18 am »
hehe.. makes me think of a glue gun.. Entire stage melting and being fed into the engine.. but probably a bit speculative for this thread :)

Offline RanulfC

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Re: Two stage, Vertical takeoff, Chemical rocket (fully) RLV
« Reply #48 on: 03/22/2010 11:55 am »
indaco1:
Not "stupid" at all acutally :) Where do you think the "original" idea of an "aluminum" fuel rocket came from? Someone fairly early on wondered if you could use the Shuttle-ET as "fuel" for orbital operations :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

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