sevenperforce

Challenge discussion: Orbital PSTO Shuttle

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I've posted a challenge over in the gameplay challenges forum but I thought it could use a discussion thread. Here's the link: 

This thread is for discussion of different launch configurations to achieve a fully-reusable orbital shuttle with parallel staging. Lots of pros and cons to different configurations and engine types and recovery options, so I'm interested to see where the discussion goes.

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I'm not sure why it can't be discussed in your original thread.

I think that for a fully reusable multiple-stage launcher, the ITS configuration makes the most sense. Although it could be smaller. You would need to combine the F9 upper stage and the Dragon into a single lifting body design

Edited by Nibb31

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41 minutes ago, Nibb31 said:

I'm not sure why it can't be discussed in your original thread.

I think that for a fully reusable multiple-stage launcher, the ITS configuration makes the most sense. Although it could be smaller. You would need to combine the F9 upper stage and the Dragon into a single lifting body design

Discussion of the spaceflight/science applications is discouraged in Challenge threads, I think.

The ITS configuration is cool, but I was specifying a parallel-staged configuration to make it more interesting.

Even if you go with the ITS configuration, however, there are still a couple of problematic hurdles. LAS is one; the ITS orbiter has barely over 1 gee of T/W fully-fueled. Tail-first vertical landing is also a high-risk maneuver and it makes egress difficult; without any alternate abort system it's really risky.

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I think that experience with the Shuttle has proven twice that parallel staging isn't a good idea.

I mentioned the ITS general configuration, not necessarily the exact vehicle. There are several possible abort options that you could fit into that design, including higher-thrust engines or a separable capsule with a pusher ring.

Edited by Nibb31

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36 minutes ago, Nibb31 said:

I'm not sure why it can't be discussed in your original thread.

I think that for a fully reusable multiple-stage launcher, the ITS configuration makes the most sense. Although it could be smaller. You would need to combine the F9 upper stage and the Dragon into a single lifting body design

First was in KSP, this is about an real life solution. 
I would probably go single stack, Simplest would be an larger rocket, think new glen size, you land upper stage and pod independently as its safer, it also let you use upper stage for satellite launches without changes. with an disposable upper stage you have an heavy lift rocket. 

An integrated upper stage would be something like an smaller and more practical version of mars colonial transporter, more complex but could give you something who could do independent missions like the space shuttle did. 

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1 hour ago, Nibb31 said:

I think that experience with the Shuttle has proven twice that parallel staging isn't a good idea.

I mentioned the ITS general configuration, not necessarily the exact vehicle. There are several possible abort options that you could fit into that design, including higher-thrust engines or a separable capsule with a pusher ring.

Parallel staging seems to be limited to solid boosters arranged around the main booster depending on initial thrust needed (some allow asymmetry).  I doubt that anyone wants to build another shuttle.

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1 hour ago, Nibb31 said:

I think that experience with the Shuttle has proven twice that parallel staging isn't a good idea.

That's why I specified 0/0 LAS -- a launch abort which is capable of functioning from zero altitude, zero velocity all the way up. The Shuttle had nothing remotely approaching LAS. Challenger survived the SRB RUD; it just broke up from off-axis aerodynamic forces at max-Q, something an orbiter with proper LAS would be designed to handle. Parallel staging wasn't really the problem there. Columbia was a victim of foam insulation shedding, which was a ridiculous problem with the External Tank, but wouldn't be an issue with anything other than hydrolox.

2 hours ago, Nibb31 said:

I mentioned the ITS general configuration, not necessarily the exact vehicle. There are several possible abort options that you could fit into that design, including higher-thrust engines or a separable capsule with a pusher ring.

I like the idea of a solid pusher ring that remains attached to the top of the booster on nominal launches so that its dry mass doesn't have to be carried into orbit unnecessarily.

2 hours ago, magnemoe said:

I would probably go single stack, Simplest would be an larger rocket, think new glen size, you land upper stage and pod independently as its safer, it also let you use upper stage for satellite launches without changes. with an disposable upper stage you have an heavy lift rocket. 

An integrated upper stage would be something like an smaller and more practical version of mars colonial transporter, more complex but could give you something who could do independent missions like the space shuttle did. 

I had specified parallel staging because I wanted to see what configurations people might be able to come up with. If you have an orbiter with its own launch engines, the booster functions less like a launch vehicle and more like a launch assist booster with integrated drop tank. The orbiter might actually be significantly larger than the booster (which eliminates several parallel staging problems).

If you do go serial with a scaled-down MCT, you can conceivably mount the engines perpendicular to the vehicle axis, since they would only fire once out of the atmosphere. Then they can be used for horizontally-oriented propulsive landing, Harrier-style.

1 hour ago, wumpus said:

Parallel staging seems to be limited to solid boosters arranged around the main booster depending on initial thrust needed (some allow asymmetry).  I doubt that anyone wants to build another shuttle.

What about a VTHL near-SSTO that uses a pair of strap-on boosters with integrated drop tanks?

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The main issue I see with full reusability is that in the standard SpaceX Pod renters, first stage lands, the second stage would have issues with reentry. I want to see an engine that can have those temperature variations (Firing-Vaccum-Compression Heating) and still be worth returning.  Maybe you could get some sort of extendable shroud, but that would really cut into payload weight.

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The 2nd stage reenters at 8 km/s speed, rather than 1.5 of the 1st stage.
It sustains 8-9 g and >1500 K. Itself it is a thin envelope made of aluminium, weak against sideways tensions.
So, unlikely it can survive axial atmospheric break, it's prograde side will deform, while its walls will become an accordeon.

So, to return 2nd stage from orbit, one should make it brake with its side and cover this side with a heat protection.
Also he should strengthen its weak body of a big canister. And add aerodynamic surfaces to fly.

As a result you get 3 options:

1) A Space Shuttle with the orange tank between its head and tail. Bulky and unviable way,

2) Energy-2 way. With telescopic or extending/retracting body and wings.

http://www.buran.ru/htm/41-3.htm

Spoiler

gk-175.gifgk175-14.jpg

 

3) Something like this, but with fuel tank instead of cargo;

Spoiler

parash3.gif


Anyway you get a bulky and heavy monster to save a 20-50 t aluminium can.

 

According to wiki, Space Shuttle's solid fuel booster contains 500 t of 16%-aluminium fuel. I.e. it depletes 160 t of aluminum powder per flight just as a fuel.

Shuttle's orange tank weights just < 30 t.

So, do you really need to save a 30 t aluminium can burning 160 t of aluminium powder?
Probably, you should just improve your way of making this can as easy as fuel.

Also you don't need that stupid way when the Shuttle contains both 12 t spacecraft (cabin) and 25 t of cargo per every flight.
Let it be smaller, carry 25 t of crago in total. For crewed flights that means 12 t cabin + 12 t of cargo.

No need to deliver rare single use heavy things like ISS module by a reusable craft. You can do this with a single-use 2nd stage.

Edited by kerbiloid

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6 hours ago, kerbiloid said:

The 2nd stage reenters at 8 km/s speed, rather than 1.5 of the 1st stage.
It sustains 8-9 g and >1500 K. Itself it is a thin envelope made of aluminium, weak against sideways tensions.
So, unlikely it can survive axial atmospheric break, it's prograde side will deform, while its walls will become an accordeon.

So, to return 2nd stage from orbit, one should make it brake with its side and cover this side with a heat protection.
Also he should strengthen its weak body of a big canister. And add aerodynamic surfaces to fly.

You get a bulky and heavy monster to save a 20-50 t aluminium can.

Also you don't need that stupid way when the Shuttle contains both 12 t spacecraft (cabin) and 25 t of cargo per every flight.
Let it be smaller, carry 25 t of crago in total. For crewed flights that means 12 t cabin + 12 t of cargo.

No need to deliver rare single use heavy things like ISS module by a reusable craft. You can do this with a single-use 2nd stage.

I agree. At a basic, conceptual level, there's no reason to insist on total reuse when you're launching comsats and cargo. It's much cheaper to throw away the engine and tank on the upper stage than to try and bring them back for refurbishment.

But if you're talking about shuttling crew/passengers into orbit, then it is assumed you'll be bringing people back down as well. And that's where a totally-reusable system starts to make a lot more sense. Granted, there's no current market for high-capacity, high-frequency passenger service to and from orbit, but that's beside the point; if there was a market for orbital passenger service, that's when we'd need a reusable man-rated shuttle, and I'm thinking that PSTO would outperform SSTO or TSTO in this function.

The Shuttle was designed with lots of crossrange capability to permit RTLS on military polar orbit launches, but a high-capacity high-frequency passenger service would be focused on equatorial launches. So wings aren't completely necessary. You do, however, want to be able to land on land, and you want to have safe, reliable landings with relatively rapid egress.

So those are the kinds of considerations at play here.

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