How does one build a shuttle?

[Chel]

How does one actually build a space shuttle using the Mk3 parts? Is it the Mk3 cockpit, cargo bay, fuel tanks, engine bit, and the delta wings and tail fin? Do you use the large landing gear? Where do you put the parachutes? What do you put on the nose of the cockpit? The aerodynamic nosecone, parachute, air intake? What engines do you use? I'm a bit confused about it, so how do you actually build a space shuttle using the Mk3 parts?

[Alshain]

 

10 minutes ago, KerbalManiac said:

How does one actually build a space shuttle using the Mk3 parts? Is it the Mk3 cockpit, cargo bay, fuel tanks, engine bit, and the delta wings and tail fin?

That's the list I guess.

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Do you use the large landing gear?

You may not need the really big ones, but you need at least the double wheel.

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Where do you put the parachutes?

Somewhere on the back, it's not super important as long as it isn't in the heat.  I usually put them near the base of the engines.

 

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What do you put on the nose of the cockpit?

Nose cone is all you really have in stock.  You don't need intakes for a standard shuttle, and a parachute would probably pull you around the wrong way there.

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What engines do you use?

The Vector is designed for it, but they are not the only option. (In fact they may be too powerful).

Space shuttles can be quite difficult.  The hardest parts are

1. Getting the engines balanced across the center of mass so it doesn't go tumbling on takeoff.
2. Getting the drag and mass balanced  so it doesn't go tumbling on re-entry.

 

Don't overbuild.  One of the biggest mistakes people seem to make when designing an STS lookalike is using the large cargo bay, but that isn't proportionally sized to match the STS and will mess with your balance.  Of course you don't have to build an STS lookalike either.

 

Edited May 9, 2017 by Alshain

[Spricigo]

There's several ways to build a shuttle 

notice KSP shuttles don't look like NASA shuttle. 

The reason is because something that looks like the real shuttle probably fly poorly if at all. 

[ARS]

3 hours ago, Spricigo said:

something that looks like the real shuttle probably fly poorly if at all. 

Nah, even a real shuttle flies poorly anyway, it cannot fly under it's own engine like an aircraft. It's basically performing "controlled gliding to runway" after the reentry. There's a reason it's called flying brickyard

[AeroGav]

As an experienced spaceplane builder i can tell you that building a shuttle lookalike is one of the hardest challenges you will face.     Asymmetrical thrust, engines that are much heavier (and more powerful) than they should be , and absence of body lift mean you are giving yourself huge handicaps.

I'd recommend you build  normal, symmetrical spaceplanes first,  if you have not already done so.  Jet engines & auxiliary fuel tanks on drop pods below the wing are a legit way to get a bit of extra payload fraction if you're not staying 100% re-usable.   These can be mounted in pairs  under your CG and in line with the axis of thrust, no major handling issues to deal with unlike a shuttle clone.

The next step is probably to build a "shuttle lite".   This can look quite a lot like a space shuttle, but I recommend the following changes to the orbiter (minimal loss of visual fidelity) -

• Use terriers or aerospikes on the back of the fuselage instead of Vectors.   Instead of engines weighing 4 tons, you'll be using 0.5-1 ton motors instead, giving you a much nicer CG.
• Angle the strakes up slightly with the fine rotation tool, so that it glides at a moderate nose up angle with no control input applied and SAS off.   This reduces how hard you'll have to shove the tail down with the elevons to keep the nose up, making it glide better and reducing landing speed.
• use the CRG-50 in the middle of the fuselage, and put short rocket fuel tanks ahead and behind.   You are carrying fuel internally, no horrible external tank to screw up the handling.

Because it will be woefully underpowered with 3 vacuum engines, you'll need 4 SRBs to get her in to space.  Actually, this is in line with the real shuttle , where 80% of the thrust was in the SRBs (and over 50% of the mass too, solid fuel is much denser than LH2!).     The advantage of 4 kickbacks is you can arrange them with 4 way symmetry around the fuselage and not have to deal with the off axis thrust of the real thing.

Even then, you still have a tricky gravity turn to make, because it goes from ludicrously overpowered (4 kickbacks) to rather underpowered when the SRBs burn out.   Once on liquid power,  you need to fly it like an aircraft as your TWR is likely less than 1, this means maintaining a decent AoA to get lift without too much drag.   If your SRB climb was too steep, you'll be too high to get any lift and will start plunging back into the atmosphere.

Note - the above example used configurable containers mod to  make the wings and strakes hold monoprop rather than LF.   Craft file is linked in the video, you can download the ship without that mod as it only needs to be present during the build to make the tanks hold mono fuel.

3 kickback boosters,  a poodle, 3 terriers and 3 puffs !

Note  - you could consider mounting a NERV also to make use of the LF capacity of the wings/strakes,  though that means clipping it inside the mk3 engine mount to not look silly and using terriers to keep the rear end from being too heavy.    

 

[Spricigo]

4 hours ago, ARS said:

It's basically performing "controlled gliding to runway "  after the reentry. 

Which is the designed flight profile to the RL STS. Much better than spinning uncontrolled like the KSP STS replicas usually do. 

AeroGav,  

surprisingly enough the Swivel is a viable option for Shuttle lite. But if you are dealing with asymmetric thrust, asymmetric drag and shifting CoM then Thuds,  with 8° gimbals,  are serious contenders. 

 

All in all,  shuttle (even the one in real world)  are very kerbal design. There's so many reasons to not work properly but yet it get the job done. 

[klesh]

On top of what everyone has said, the most difficult part of a shuttle replica is re-entry and aerodynamic stability.  Usually upon return your cargo has been deployed and your fuel burned leaving very heavy engines at the back making your shuttle unstable.  Its very important to understand how to make a stable plane in KSP, and then apply this to what your re-entry shuttle's weight and lift distribution. Lift behind the CoM, which is difficult when the heaviest thing is on the back of your ship.  

In addition to translating the wings and ailerons for best effect, I've also taken to using RCS fuel as ballast for re-entry, to keep the nose of the plane as heavy as I can make it to balance against the engines.  I carry an amount of RCS fuel that I dont intend to burn (except for when i am gliding in, burning it continually to reduce mass) specifically to reorient my CoM.  The amount of RCS will vary, but looking at your shuttle in the SPH will reveal how much is needed to shift your CoM around during the different stages of the mission.  

Its probably not the most elegant solution and certainly not efficient, but I like it and it works for me.

[AeroGav]

1 hour ago, klesh said:

On top of what everyone has said, the most difficult part of a shuttle replica is re-entry and aerodynamic stability.  Usually upon return your cargo has been deployed and your fuel burned leaving very heavy engines at the back making your shuttle unstable.  Its very important to understand how to make a stable plane in KSP, and then apply this to what your re-entry shuttle's weight and lift distribution. Lift behind the CoM, which is difficult when the heaviest thing is on the back of your ship.  

In addition to translating the wings and ailerons for best effect, I've also taken to using RCS fuel as ballast for re-entry, to keep the nose of the plane as heavy as I can make it to balance against the engines.  I carry an amount of RCS fuel that I dont intend to burn (except for when i am gliding in, burning it continually to reduce mass) specifically to reorient my CoM.  The amount of RCS will vary, but looking at your shuttle in the SPH will reveal how much is needed to shift your CoM around during the different stages of the mission.  

Its probably not the most elegant solution and certainly not efficient, but I like it and it works for me.

Yes, that's why i try to keep the total mass of the engine cluster below 4T, so the cockpit balances it even when all the fuel and cargo is gone.   Mine glides nice and stable when empty but it does mean a severe transition from ZOMG boosters to asthmatic flea after staging.

 

[Spricigo]

10 minutes ago, AeroGav said:

Yes, that's why i try to keep the total mass of the engine cluster below 4T, so the cockpit balances it even when all the fuel and cargo is gone.   Mine glides nice and stable when empty but it does mean a severe transition from ZOMG boosters to asthmatic flea after staging.

Instead of building a shuttle that ascend like a rocket and descent like a barnyard door you did one that fly like a plane all the way. ...So AeroGav.

I guess its hard to you endure a shuttle that have 'just enough' stability for controlled glide to runaway. But that is the idea behind the concept.  Since the wings (in a typical shuttle) are not used during the ascent the concern with mass and drag asks for minimal amount. Likewise the main engines are not vacuum engines but atmospheric engines, preferable with large gimbals to deal with asymmetrical thrust, asymmetrical drag and shifting CoM. And since we are rocketing our way into space we want all engines lit at once right at the launchpad (except, maybe, for a much weaker and efficient orbital engine)

Looking at your typical design I'll be much surprised when you show up with something like that.

[Hummingbird Aerospace]

On 5/8/2017 at 8:30 PM, The_Cat_In_Space said:

What do you put on the nose of the cockpit? The aerodynamic nosecone, parachute, air intake?

Usually I like to put a clamp-o-torn shielded docking port on the front. It looks cool, eliminates the need for separate docking ports, and has the same aerodynamic value as the nose cone.

 

[ArmoredLipid]

Notice that most Mark 3 parts are, as I am fond of saying, as heavy as armored vehicles. As such, don't bother trying to make your first attempt look like the Space Shuttle - it won't help efficiency a bit. Strap on anything with a TWR of over 1 and use Mark 3 parts for your reenterer. Parachutes should go on the ends, and work their way in. Do not put one on the nose. Calculate how much fuel you will need to reenter and fill your tanks to slightly above that - again, fully fueled, these parts are heavy for something that's supposed to be an aircraft. If you're trying to land on a runway, add the radial-mount main chutes on the back. Landing gear should be as heavy as you have, and if you have the Big-S delta wings (i.e. fuel storage wings) use them.