Author Topic: Lunar-capable shuttle  (Read 5031 times)

Offline Caleb Cattuzzo

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Lunar-capable shuttle
« on: 10/23/2017 06:38 PM »
I've been trying to design a lunar capable shuttle for awhile now and I've hit a road block.does anyone know what the fuel usage per second is for the SSME's?And could a LO2/LH2 tank fuel it in a 15 by 20 ft space?
« Last Edit: 10/23/2017 06:39 PM by Caleb Cattuzzo »
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Offline SweetWater

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Re: Lunar-capable shuttle
« Reply #1 on: 10/23/2017 06:59 PM »
I've been trying to design a lunar capable shuttle for awhile now and I've hit a road block.does anyone know what the fuel usage per second is for the SSME's?And could a LO2/LH2 tank fuel it in a 15 by 20 ft space?

The SSME was throttleable from (I believe) 65% to 109% of rated power. The rate of consumption of fuel and oxidizer would depend on what level of thrust you were trying to achieve. My understanding of rocket engines is limited, but I believe that while percentage of thrust and fuel/oxidizer consumption are related, they do not scale precisely linearly (i.e. consumption at 75% of rated thrust is NOT 75% of consumption at 100% of rated thrust).

As for whether SSMEs could run using the LO2/LH2 in a 15 x 20 foot tank, my guess would be not for a very long time.

I'm curious as to why you want to use the shuttle as a basis for a lunar-capable vehicle. The wings, for example, are a lot of mass that is useless on/around the moon but needs to be propelled there (and, presumably, back) anyway. Shuttle TPS wasn't designed to re-enter at lunar velocities, the SSME required a lot of ground support equipment to start and couldn't be re-started in space.

Also, FWIW, if you are going down this rabbit hole, you might want to read up on Shuttle Centaur if you haven't already. It would probably help you ballpark how much LO2/LH2 could be fit into an insulated tank in the cargo bay, if you really wanted to try.

Online DaveS

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Re: Lunar-capable shuttle
« Reply #2 on: 10/23/2017 07:08 PM »
Here's an old Langley Research Center (LaRC) document on the subject that I found a while back:
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Offline redliox

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Re: Lunar-capable shuttle
« Reply #3 on: 10/23/2017 07:37 PM »
The STS (i.e. the space shuttle) is retired bear in mind.  The SSME's are modified to be disposable now, and the boosters and tankage are just short of being totally new elements because the needs of the SLS are greater than that of the previous STS.  I don't really recommend imagining a new winged space shuttle although you could conceive of a vehicle that rides atop either SLS, ITS, or New Glen.
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Offline Caleb Cattuzzo

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Re: Lunar-capable shuttle
« Reply #4 on: 10/24/2017 05:25 AM »
I am using the STS as a basis for my design since it is the only operational orbital spaceplane to date.As for getting a shuttle type vehicle lunar capable I was thinking of something along the lines of the shuttle-Saturn concept except with a SLS first stage and boosters for LEO and the external tank for TLI.For thermal protection the vehicle would use a full belly heat shield that can easily be replaced after each mission greatly reducing the turn around time but it would weight about 20,000lbs.That is just the few issues Iím working on right now Iím still early in the design process most of it is still in my head.I would love some help please.
« Last Edit: 10/24/2017 05:26 AM by Caleb Cattuzzo »
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Offline hkultala

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Re: Lunar-capable shuttle
« Reply #5 on: 10/24/2017 06:07 AM »
I am using the STS as a basis for my design since it is the only operational orbital spaceplane to date.

Wrong. X-37B is also operational, and Buran was operational.

But spaceplanes make no sense on Luna as Luna has no atmosphere.

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As for getting a shuttle type vehicle lunar capable I was thinking of something along the lines of the shuttle-Saturn concept except with a SLS first stage and boosters for LEO and the external tank for TLI.

SLS staging is very different from Saturn staging so a "shuttle-saturn" type vehicle cannot be made from SLS.


And RS-25 is designed to be started once, on ground, and to be an engine that works on atmosphere. Does not work as an upper stage/orbital engine, and even if it would work, would be less than optimal. (Ares I was originally planned to use RS-25 but after they found it's too hard to modify to start in the air, thy gave up and switched to J-2X)



ps. SpaceX has already revealed their concept for "lunar-capable shuttle".
« Last Edit: 10/24/2017 06:22 AM by hkultala »

Offline Caleb Cattuzzo

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Re: Lunar-capable shuttle
« Reply #6 on: 10/24/2017 06:16 AM »
Sorry ment to add manned into that statement about the shuttle.Also the point of it having wings is so it can fly to its landing site in earthís atmosphere making it much easier to recover plus the size and space of a shuttle like craft means it can act as sort of a temporary orbit laboratory while landers are deployed to the surface or orbital station construction is going on.It also makes the crew a lot more comfortable and the cargo bay allows bigger cargo to be transported to and from the moon giving it a advantage over capsules.

P.S Iím typing this at midnight so some of it wonít make sense 😂
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Offline ChrisWilson68

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Re: Lunar-capable shuttle
« Reply #7 on: 10/24/2017 06:19 AM »
I am using the STS as a basis for my design since it is the only operational orbital spaceplane to date.

Wrong. X-37B is also operational, and Buran was operational.

Also, Apollo was operational, and it's the only system that was ever operational that could send people to the surface of the moon and back.

If you care about operational, Apollo is the only game in town.  Trying to make changes to STS to make it capable of taking people to the moon and back would be such enormous changes that it wouldn't be STS at all any more, so the "operational" bit wouldn't apply.

Offline ChrisWilson68

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Re: Lunar-capable shuttle
« Reply #8 on: 10/24/2017 06:26 AM »
Sorry ment to add manned into that statement about the shuttle.Also the point of it having wings is so it can fly to its landing site in earthís atmosphere making it much easier to recover

I don't think you have any realistic sense of how staggeringly impractical it is to carry those wings to the surface of the moon and back just to use them for landing.

plus the size and space of a shuttle like craft means it can act as sort of a temporary orbit laboratory while landers are deployed to the surface or orbital station construction is going on.

Anything remotely like the shuttle wouldn't be able to land on the moon and then take off again, so what you could do with it if it could is moot.  You might as well imagine what you could do if thestrals pulled your carriage to the moon.

It also makes the crew a lot more comfortable and the cargo bay allows bigger cargo to be transported to and from the moon giving it a advantage over capsules.

Capsules can't land on and take off from the moon either.  That's why Apollo used a specially-built lunar lander, which left a part of itself on the surface.

It's not easy landing on the moon then getting back to orbit.  It takes a very special design to be able to even do it.

P.S Iím typing this at midnight so some of it wonít make sense 😂

If you want something that makes sense, go with hkultala suggestion and start with SpaceX's ITS.

Offline hkultala

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Re: Lunar-capable shuttle
« Reply #9 on: 10/24/2017 06:42 AM »
Sorry ment to add manned into that statement about the shuttle.Also the point of it having wings is so it can fly to its landing site in earthís atmosphere making it much easier to recover

The big wings of the SLS were made to allow ~3000 km crossrange for military missions that do single polar orbit and return to the launch site.

This kind of flights were NEVER done and all shuttle flights carried many tons of extra weight due this. Much smaller wings would have been enough for flying to the landing site for all the missions that DID took place.

For all civiliian  use, it makes much more sense to just wait for earth to rotate so that the landing site rotates under the craft and then land, without the need for big crossrange. And even the Apollo capsule could steer itself in the atmosphere, even though it did not have any aerodynamic surfaces.

And powered landing has been proven to work by spacex.

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plus the size and space of a shuttle like craft means it can act as sort of a temporary orbit laboratory while landers are deployed to the surface or orbital station construction is going on.It also makes the crew a lot more comfortable and the cargo bay allows bigger cargo to be transported to and from the moon giving it a advantage over capsules.

P.S Iím typing this at midnight so some of it wonít make sense 😂

Please, do even the most simplest weight and delta-v calculations first.

There are very good reasons STS never reached even 1000km orbit
« Last Edit: 10/24/2017 06:44 AM by hkultala »

Online Welsh Dragon

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Re: Lunar-capable shuttle
« Reply #10 on: 10/24/2017 07:52 AM »
Capsules can't land on and take off from the moon either.  That's why Apollo used a specially-built lunar lander, which left a part of itself on the surface.
Apollo baselined landing of the CSM for a good while. I believe the direct ascent requirement sized the CMS engine.

Offline Caleb Cattuzzo

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Re: Lunar-capable shuttle
« Reply #11 on: 10/24/2017 02:16 PM »
Again the shuttle will NOT land on the moon but I see a chance for it to take multiple landers or station modules to lunar orbit and make lunar access a lot more accessible the STS is my baseline that I am using as a basis for my own design it probably wonít even remotely look like the STS when Iím done.So if in theory the orbiter was mounted on the top end of the rocket like the Saturn-shuttle would it be stable on takeoff and accent?

P.S I really donít trust the ITS right now that many engines on one rocket is never a good idea like the Russian N1 moon rocket.
« Last Edit: 10/24/2017 02:18 PM by Caleb Cattuzzo »
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Offline hkultala

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Re: Lunar-capable shuttle
« Reply #12 on: 10/24/2017 02:31 PM »
Again the shuttle will NOT land on the moon but I see a chance for it to take multiple landers or station modules to lunar orbit and make lunar access a lot more accessible

Homework #1: How much delta-v is needed to go from LEO to LLO?

Homework #2: What does this mean in terms of ratios of mass on LEO,  mass on LLO, and return mass towards earth on return trip?
Assume some realistic engine isp.

You can use this delta-v calculator:

http://www.quantumg.net/rocketeq.html

homework #3: How does these numbers change when you assume easily storable propellants for your return trip, decreasing the isp.


Before these numbers are calculated, it makes no sense to start thinking anything else about the specifications of your craft.

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the STS is my baseline that I am using as a basis for my own design it probably wonít even remotely look like the STS when Iím done.

As it has been multiple times explained, STS is a very, very bad baseline for a lunar mission.

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So if in theory the orbiter was mounted on the top end of the rocket like the Saturn-shuttle would it be stable on takeoff and accent?

accent? What does that mean?

Quote
P.S I really donít trust the ITS right now that many engines on one rocket is never a good idea like the Russian N1 moon rocket.

Like too many cylinders are not good for a car?

There are no technical problems from multiple engines, when the system is properly designed for it.

N1 did not fail because of too many engines. it failed because of:
1) bad quality components
2) pogo oscillation
3) differential steering
4) buggy control computer
5) lacking engine shielding

Actually, many of the problems of the N1 could have been AVOIDED BECAUSE it had so many engines, and it could have reached BETTER reliability than corresponding rocket with less engines, if:
1) The engines would have been properly shielded in case of breakage of one engine (like spaceX engines are shielded)
2) The control computer would have had smarter control algorithms and less bugs.


By using enough engines, the system can become fault-tolerant, allowing mission to complete even when some engine fails. Both Falcon 9 and Saturn V have demonstrated this. And the more engines there are, the smaller is the performance loss from single engine failure, and the earlier the engine failure can happen without LOM.
« Last Edit: 10/24/2017 02:46 PM by hkultala »

Online nacnud

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Re: Lunar-capable shuttle
« Reply #13 on: 10/24/2017 02:37 PM »
I'm sorry to say but there is no way to get the shuttle to low luna orbit. You need about 10 km/s to get to low earth orbit, and another 5.5 km/s to get to LLO and back.


You can use this ∆v calculator to work out how much ∆v the shuttle could have had if you fill the payload bay with propellant.

Some (generous) numbers to start with.

Dry mass of orbiter, ~ 68500kg
Payload ~ 25000kg
ISP of RL10 upper stage engine ~ 470s
Mass of modifications 0kg (I did say generous)

Calculated ∆v =  1.4 km/s not enough to get even half way to geo.

« Last Edit: 10/24/2017 02:53 PM by nacnud »

Offline john smith 19

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Re: Lunar-capable shuttle
« Reply #14 on: 10/24/2017 02:41 PM »
Here's an old Langley Research Center (LaRC) document on the subject that I found a while back:
Excellent find.

That outlines pretty much everything this guy's asking about, as well as why it's a very challenging approach to the problem.  :)

I think the ten additional Shuttle C HLV flights to load up the ET with enough prop to fly the mission (and another 1 for the boiloff) give some idea of the scale of the task.  :o
« Last Edit: 10/24/2017 02:43 PM by john smith 19 »
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Offline Caleb Cattuzzo

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Re: Lunar-capable shuttle
« Reply #15 on: 10/24/2017 02:49 PM »
Thanks for the homework questions Iíll look into it.Is there any restart able engines you guys recommend for my crafts main engines?Some where in the 1,500-ish KN would be preferable.Also would a full belly heat shield be a good idea?I was thinking it would be a safer and easier design then the tps the shuttle used if it would be disposed and replaced after a reentry.
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Re: Lunar-capable shuttle
« Reply #16 on: 10/24/2017 02:55 PM »
Again the shuttle will NOT land on the moon but I see a chance for it to take multiple landers or station modules to lunar orbit and make lunar access a lot more accessible the STS is my baseline that I am using as a basis for my own design it probably wonít even remotely look like the STS when Iím done.So if in theory the orbiter was mounted on the top end of the rocket like the Saturn-shuttle would it be stable on takeoff and accent?

P.S I really donít trust the ITS right now that many engines on one rocket is never a good idea like the Russian N1 moon rocket.

Well, once you remove the wings (as they are useless dead weight) and the cargo bay (not necessary), you'll wind up with a capsule for the crew. I think you'd do better with reusable fairings as a starting point.

The N1 never failed because it had too many rocket engines. It had numerous other flaws which would have caused it to fail even with fewer engines. Importantly, those engines (and many other components of the rocket) were not properly ground-tested, the N1 in general did not have good quality control, it had POGO issues, and initially it had a terrible flight control computer system with an insufficient amount of sensors. For more information, see this thread: https://forum.nasaspaceflight.com/index.php?topic=41432.0
In short, it wasn't a well-designed rocket. The US Saturn series was successful in no small part because it was well-designed and extensively ground-tested.
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Offline john smith 19

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Re: Lunar-capable shuttle
« Reply #17 on: 10/24/2017 03:00 PM »

The big wings of the SLS were made to allow ~3000 km crossrange for military missions that do single polar orbit and return to the launch site.
Not quite. This document

https://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts_overview.html

Says it was 1100nm, about 2046Km.
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To provide the abort-once-around capability in polar orbit launches.
Because in fact the ground track is actually a spiral, not a circle.

This would have been flying out from Vandenberg and never in fact happened.

This item alone sank a shed load of wind tunnel time (virtually no CFD available) and money for effectively no benefit.  :(

It would be interesting to see how simple the wing layout could have been if the brief was just "Land it at any adequately long runway fairly near its ground track. We'll figure out recovery if we ever need to do it."
« Last Edit: 10/24/2017 03:01 PM by john smith 19 »
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Online nacnud

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Re: Lunar-capable shuttle
« Reply #18 on: 10/24/2017 03:10 PM »
It would have been something like this, MTKVA

Offline Archibald

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