Build a better Shuttle

[sevenperforce]

Discussion of Russian vs US launch vehicles and Buran vs Shuttle vs Soyuz got me thinking. I'm sure all of us here are well aware that the Shuttle program was based on some ill-conceived notions, both with respect to the demand for flights as well as the capability of NASA to execute rapid Shuttle turnaround. The Shuttle had some neat capabilities (launching payload along with service crew, e.g. Hubble) and promised abilities (sat recovery), but it was never really used like it could have been. And the flight rate was so low that reuse cost more than it saved. 

But what if they had been right about the demand for the Shuttle's abilities? What if the market demanded a launch vehicle that could sent up large payloads along with crew, as well as occasionally retrieving sensitive cargo from orbit? What if the market was so saturated with demand that economies of scale were in full swing?

It's clear that even under those circumstances, the Shuttle's high refurbishment cost and lengthy turnaround time wouldn't have been the best fit (even ignoring its safety record). But what might have been better? If you were designing a launch vehicle with these sorts of target capabilities, how would you go about it?

[tater]

 

 

It would need a return aeroshell for bringing stuff down, I suppose.

 

Edited April 24, 2017 by tater

[sevenperforce]

11 minutes ago, tater said:

 

It would need a return aeroshell for bringing stuff down, I suppose.

 

Rhombus was always a nice concept -- beats out SERV handedly by using recoverable drop tanks and not worrying about the landing turbojets. Did it have any crew+cargo option? And what about LES?

[tater]

Upper left in lower illustration shows a gemini capsule inside the mini version.

You could just as well design something similar with a capsule as an optional top component (with BO/SpaceX style LES). These short, squat vehicles have nice diameter for payloads that are more volume than mass limited (inflatables, etc).

[sevenperforce]

5 minutes ago, tater said:

Upper left in lower illustration shows a gemini capsule inside the mini version.

You could just as well design something similar with a capsule as an optional top component (with BO/SpaceX style LES). These short, squat vehicles have nice diameter for payloads that are more volume than mass limited (inflatables, etc).

A capsule with pusher-style LES has the advantage of being able to act as a lifeboat if the orbiter is damaged on launch or in LEO. It can also abort on landing if there's a problem. Sitting around for the gantry tower to pick you up would be a bit unpleasant, though.

[tater]

Yeah, that's why you'd need it on top, not under the fairing.

[sevenperforce]

13 hours ago, tater said:

Yeah, that's why you'd need it on top, not under the fairing.

What about something with the payload capabilities of the Shuttle? In other words, you have very good economies of scale w/r/t launch frequency, but still no need for 400-tonne payloads.

[tater]

The payload capacity of the Shuttle is Falcon Heavy or so. 20 tons to LEO. 

[sevenperforce]

25 minutes ago, tater said:

The payload capacity of the Shuttle is Falcon Heavy or so. 20 tons to LEO. 

But it can't deliver cargo and crew at the same time, and it has no downmass capabilities.

So let's say you need to be able to launch:

• A half-dozen crew to LEO
• 20-tonne payloads to LEO
• 20-tonne payloads with a half-dozen crew
• A payload recovery vehicle

And you need to be doing all four regularly enough that a reusable multipurpose LV makes good economic sense.

How do you go about doing it?

[tater]

Why make one, bad vehicle, instead of having vehicles for different purposes? A dual launch of FH with cargo, and a D2 with the crew, and perhaps some sort of SM package (and robot arm?) in the trunk would do.

The problem with Shuttle was that it tried to do too much. The extant commercial crew vehicles can do taxi service to LEO. Heavy payloads should be lifted with heavy lifters. 450 tons means that you build what you need, and you don't need to mess around with 200 launches of 20 tons, you send it all up in one go, or maybe 2 if volume is an issue. Send the crew up on the little brother.

[sevenperforce]

38 minutes ago, tater said:

Why make one, bad vehicle, instead of having vehicles for different purposes? A dual launch of FH with cargo, and a D2 with the crew, and perhaps some sort of SM package (and robot arm?) in the trunk would do.

The problem with Shuttle was that it tried to do too much. The extant commercial crew vehicles can do taxi service to LEO. Heavy payloads should be lifted with heavy lifters. 450 tons means that you build what you need, and you don't need to mess around with 200 launches of 20 tons, you send it all up in one go, or maybe 2 if volume is an issue. Send the crew up on the little brother.

In other words, your answer is, "Forget designing a multipurpose craft; focus on getting launch cadence high enough that parallel crew and cargo launches is no problem." Doesn't solve the problem of downmass, but other than that, it's solid.

A possible solution is parallel staging with a cargo bay that can accept a drop-in fuel tank. That way you can launch crew and cargo together if necessary, but if you only need to send crew up, you fill the cargo bay with additional fuel. 

[tater]

Something like the Bono craft is multipurpose, really. It can get payloads to LEO. The ;payload could be cargo, people, or a combination, but they would not be glued tot he same vehicle.  Hundreds of tons to LEO is rather a lot. 6 crew is a capsule, basically. You can stickball that in there, or design something more like the Apollo petal as a fairing. Capsule on top, cargo below. You'd lose some payload because the fairing would need to support the capsule.

But yeah, it's not as small a payload carrier as shuttle was.

Honestly, if you think about possible asteroid mining, etc, perhaps a purpose built downmass  carrier would be useful to generically carry "stuff" to a precision landing (steerable chutes?).

[Bill Phil]

The trouble with the shuttle wasn't so much in design (albeit there were issues there) but in something a bit more mundane. Infrastructure. One VAB. Only a few runways long enough. Few launchpads. One facility that could build EXTs. What they needed was a whole lot more infrastructure to support high flight rates. That and a much larger fleet. They developed the shuttle too inexpensively. 

Shuttle-C would've helped a lot as well.

[sevenperforce]

10 hours ago, Bill Phil said:

The trouble with the shuttle wasn't so much in design (albeit there were issues there) but in something a bit more mundane. Infrastructure. One VAB. Only a few runways long enough. Few launchpads. One facility that could build EXTs. What they needed was a whole lot more infrastructure to support high flight rates. That and a much larger fleet. They developed the shuttle too inexpensively. 

Shuttle-C would've helped a lot as well.

Do you think they could have improved turnaround with a higher flight rate? Seems like a lot of the design choices ended up making refurbishment just ridiculously lengthy.

[Bill Phil]

5 minutes ago, sevenperforce said:

Do you think they could have improved turnaround with a higher flight rate? Seems like a lot of the design choices ended up making refurbishment just ridiculously lengthy.

The largest limitation to turnaround time was actually how long it took to build the EXTs. Those are huge, and they have to rebuild them each launch. Increasing production capacity of EXTs will still leave a fairly long turnaround time. This is why we'd need a larger fleet of orbiters to get more launches per year.

[sevenperforce]

13 minutes ago, Bill Phil said:

The largest limitation to turnaround time was actually how long it took to build the EXTs. Those are huge, and they have to rebuild them each launch. Increasing production capacity of EXTs will still leave a fairly long turnaround time. This is why we'd need a larger fleet of orbiters to get more launches per year.

If you do the same engines-on-orbiter design, but use a series of boosters that take the same fuel as your orbiter's main engines, then you can crossfeed from your boosters to your orbiter and recover the boosters by chute/flyback/hoverslam. In cases where you don't need to loft unpressurized cargo, you can drop an auxiliary tank into your payload bay and dispense with a couple of the boosters.

Tripropellant engines might be particularly useful for this.

[magnemoe]

On 24.4.2017 at 9:41 PM, sevenperforce said:

In other words, your answer is, "Forget designing a multipurpose craft; focus on getting launch cadence high enough that parallel crew and cargo launches is no problem." Doesn't solve the problem of downmass, but other than that, it's solid.

A possible solution is parallel staging with a cargo bay that can accept a drop-in fuel tank. That way you can launch crew and cargo together if necessary, but if you only need to send crew up, you fill the cargo bay with additional fuel. 

Shuttle had too large cargo capacity for manned missions. I would reduce that to unpressurized cargo, optional arm and air lock. Then have an unmanned mission. 
The mini ITS some presented here would be pretty much perfect. Might even do an unmanned version with an larger cargo hold for satellite launches. 

[Kerbal01]

Do it the way Max Faget wanted to do it, 2 planes, one plane on top of the first. Carry the plane to high altitude and some Mach, release it to power to orbit. Booster plane goes and lands. Orbiter has jet engines 

[YNM]

"Shuttle" : moving things around between few places, preferably short and/or frequent.

You move people with bus shuttles and you move lots of goods with either box truck (piece goods) or some flatbed lorry (containers). (*insert other goods here with appropriate container*)

 

The only problem they had was to merge both. If only they didn't try that far and took responsibility of the mess instead of leaving it to a research body not really meant for it...

 

EDIT : Alright, you can always shift the astronauts as "drivers". But shuttles are meant for lots of usage. So I'd say that was the next bigger problem, other than it was quite an astoundingly large objectives they wanted to finish there. Sending a 737 up into orbit and back down, is a clean no-brainer of complexity.

Edited April 28, 2017 by YNM

[sevenperforce]

22 minutes ago, magnemoe said:

Shuttle had too large cargo capacity for manned missions. I would reduce that to unpressurized cargo, optional arm and air lock. Then have an unmanned mission. 
The mini ITS some presented here would be pretty much perfect. Might even do an unmanned version with an larger cargo hold for satellite launches. 

Why thank you, I agree that it is pretty much perfect.

I was already planning on three variants: one with a crew cabin and no unpressurized cargo bay, one unmanned with a cargo bay/fold-away fairing, and one that is just a tanker. The math works really ridiculously well.

Spoiler

Just because I'm a little thrilled with the design right now, here are the payloads I've got at present:

	LEO	GTO	ISS
Falcon 9FT (RTLS)	20.6	4.0	5.5
Falcon 9FT (OCISLY)	22.4	5.0	7.2
Falcon 9FT (expended)	25.7	6.7	10.1
Falcon Heavy (recovered)	41.0	13.1	23.0
Falcon Heavy (core expended)	49.1	16.2	30.3
Falcon Heavy (expended)	61.4	23.2	41.0

"LEO" and "GTO" are the unmanned cargo variety, with full recovery for the upper stage. Conveniently, the payload penalty for upper-stage recovery is the same for LEO missions as for GTO missions, since a lifting-body re-entry bleeds off all your velocity either way. "ISS" represents the pressurized cargo capacity to the ISS orbit and inclination from a KSC launch, with the crew cabin installed and a notional dry mass of 20.5 tonnes. The tanker (not included or referenced in the table) can get to LEO on a fully-recoverable Falcon Heavy with 40 tonnes of propellant, plus its own landing reserves.

For getting BLEO, on-orbit refueling gives us some fantastic capabilities. From this thread:

Quote

Notionally, consider the following plan for a Mars Sample Return mission:

Two-tonne rover capable of acquiring samples is launched to LEO in the cargo-variant upper stage. A tanker-variant upper stage is also launched to LEO. Both are fully refueled in orbit and exit together on TMI. After the TMI burn, the mission spacecraft has 35 tonnes of propellant remaining; the tanker has 55 tonnes of propellant remaining.

Immediately after the TMI burn, the two upper stages rendezvous and the tanker transfers 53 tonnes of propellant to the mission spacecraft, then adjusts its trajectory to perform a Martian free-return. It will have enough residuals for high-energy Earth EDL after its loop around Mars. The mission spacecraft is now 62% fueled, with 88 tonnes of propellant.

The mission spacecraft performs a high-energy entry and landing on Mars, reaching the surface on its auxiliary thrusters with 69 tonnes of propellant. The rover exits and picks up a series of samples, then returns to the mission spacecraft.

The mission spacecraft lifts off on its thrusters, fires its main engines, and rockets toward the solset on a direct ascent to Earth Injection. It performs a high-energy entry and lands on Earth with 5 tonnes of propellant to spare.

Fully-reusable Mars Sample Return with no ISRU required, at the cost of only two reusable Falcon-family launches plus refueling runs.

Adapting the same mission plan as before, but for a crewed lunar mission:

Fully-fueled manned vehicle (dry mass 20.5 tonnes, payload 4 tonnes including crew) and tanker head for TLI out of LEO together as before, with the tanker transferring its propellant reserves to the manned vehicle immediately after the TLI burn and coming back on a free-return trajectory to land. Manned vehicle reaches cislunar space with 112.8 tonnes of propellant, executes orbital entry, deorbit, and landing to reach New Tranquility Base with 48.8 tonnes of propellant remaining.

After the lunar sortie (which can last quite a while, given that total delivered payload is the same as the entire gross mass of the Apollo Lunar Ascent Module), the manned vehicle lifts off on its thrusters, ignites its main engines, and heads on a direct ascent to Earth. EDL is completed with a whopping 10.2 tonnes of propellant to spare.

 

Speaking of which, do you have a procedural parts mod, by any chance? I only have the demo, obviously without mods, so as much as I'd like to build a mockup of the mini-ITS, I cannot. I suppose I could do it in Google Sketchup, but then I couldn't do any simulated EDS goodness.

[wumpus]

On 4/24/2017 at 2:55 PM, tater said:

Why make one, bad vehicle, instead of having vehicles for different purposes? A dual launch of FH with cargo, and a D2 with the crew, and perhaps some sort of SM package (and robot arm?) in the trunk would do.

The problem with Shuttle was that it tried to do too much. The extant commercial crew vehicles can do taxi service to LEO. Heavy payloads should be lifted with heavy lifters. 450 tons means that you build what you need, and you don't need to mess around with 200 launches of 20 tons, you send it all up in one go, or maybe 2 if volume is an issue. Send the crew up on the little brother.

Because if you tell congress you are making four separate launch vehicles, you will be only be making the cheapest (depending on which districts it is made in, natch) in a week.  NASA made the shuttle with what Congress would let them build, they didn't have the option to make something effective.  Remember there were 4 parts to the "Shuttle" program (the shuttle, a space station and probably a trip to Mars, not sure about the other thing), and all but the Shuttle was cut.  We had a ferry to nowhere.

Near as I can tell, SLS *is* the "better shuttle" (or at least shuttle 2.0).  I can't say I'm a big fan, but there it is.  Amy Shira Teitel over at her Vintage Space youtube channel [as of April 28, 2017] has a current video on "followup Apollo rockets".  From the looks of it, it would have been "ALS" or "Apollo Launch System" and have most of the benefits and issues of SLS.  While it does look like a better program than the shuttle (except for other pesky political issues like being tied to a previous president), don't underestimate the "paper rocket problem".  Those "recoverable" F-1 engines would hit the water at >200km/hr and while they can take a quick dunk at shallow depths I'm not counting on them surviving what the Shuttle SRB cases did (which were much more boyant).  Remember everything spacex went through with parachutes (and plenty on this board took much convincing that parachutes wouldn't work) and also remember that 1970s computers simply weren't up to a proper sci-fi landing.

[tater]

I know the Shuttle history (vs the STS system NASA originally proposed (shuttle, tug, nuclear ferry was the "STS")). 

I think if the choice is design a huge vehicle that is supposed to do more than one thing, that's a bad solution, so yeah, SLS is better in that regard---throw a fairing around cargo, send a capsule if you need crew.

Sending a 100 ton vehicle 5 times to deliver 100 tons of cargo is absurd.

[wumpus]

On 4/28/2017 at 10:13 AM, tater said:

I know the Shuttle history (vs the STS system NASA originally proposed (shuttle, tug, nuclear ferry was the "STS")). 

I think if the choice is design a huge vehicle that is supposed to do more than one thing, that's a bad solution, so yeah, SLS is better in that regard---throw a fairing around cargo, send a capsule if you need crew.

Sending a 100 ton vehicle 5 times to deliver 100 tons of cargo is absurd.

While the saying "the customer is always right" takes plenty of abuse, customer infallibility is at its peak when they say "shut up and take my money".  Congress absolutely insisted on sending a 100 ton vehicle 5 times.  And yes, "congress" appears to be the antonym of "progress".

"Nuclear ferry"?  Was it there as a sacrificial program (they wanted just one cut, not 3) or did it have a much better chance before Three Mile Island?  I'm a bit too young to remember nuclear attitudes before that event.

[tater]

Forgetting that Three Mile Island was a disaster that never happened, nuclear is still a great idea, and will always be. It's just an engineering issue.

 

There were other concepts. The Ferry was a high Isp vehicle to move payloads to cislunar space, meant to be refueled. STS was a transportation system. Some of the concepts didn't have the cargo in the shuttle, either.

[NSEP]

Isnt the ITS bassicly a sort of shuttle or not?