KSP Stock Shuttles Thread - Post yours !

[AeroGav]

These things don't belong in SSTO threads because they aren't single stage,  nor do they even come close to it.   But they represent a significant challenge to construct, especially in the stock game.

Feel free to post your creations.   I'm not going to impose any restrictions because for one, I'm not sure what defines a "shuttle" type vehicle.   Partially, but not highly reusable,  wings, solid rocket boosters,  and a lack of airbreathing engines?

How easy is yours to fly ?  

How well does it perform ?  

How close to the real thing have you managed to get (if that was your aim?)

In terms of cost to launch and tech required, would it remotely make sense to use in a career game?

To get things started, this is my Kolumbia III.

Now that I finally figured out the Mk3 Engine Mount is supposed to have three 1.25m engines and one 2.5m to avoid open node drag ,  I built a shuttle around the part.

I wanted it to be stable and easy to fly,  so I compromised on visual similarity by going with a symmetrical arrangement of four boosters & internal fuel with no external tank.  

The Vector engines may look exactly like the RS-25 but are a bit too powerful for the job and much, much too heavy.    They give a CG that is far to the rear. The shuttle wing planform, which I kept, also has CoL far to the rear, but that means all the cargo and fuel is ahead of CG, making it excessively nose heavy when loaded and excessively unstable empty.    So, I went with the much lighter combo of 3 Terriers and a Poodle.

I still needed some way to shift the CG up a little more.   I also had this unused LF capacity in the wings that it pained me to just ignore.   So I ended up mounting a pair of NERVs to the wing strakes and panelling them in with wing segments so their presence isn't too obvious.

Looks good from this angle.  Hey Jeb, you seem to have put the boosters on the wrong side..

Like a good plumber,  I boxed in those unsightly NERVs.  You'll never realise they're there.

Hopefully everyone is too distracted by the majestic booster separation to notice we have twice as many exhaust plumes as there should be.  Maybe if I launch in the day it won't be so obvious, but then people are more likely to notice the extra SRBs. 

.

I would say successful payload delivery, but the lab module has no rcs, no power, and no probe core, so it's more a case of "fly tipping" in space.

https://kerbalx.com/AeroGav/Kolumbia-III

[Val]

Moved to Spacecraft Exchange as it doesn't qualify as a challenge: Guide Lines

[eagle92lightning]

On ‎10‎/‎30‎/‎2016 at 11:02 AM, AeroGav said:

I'm not sure what defines a "shuttle" type vehicle

a shuttle type vehicle is quite simple really its when you get to thrust to weight ratios that things get a bit complicated but here is the simple version. (thanks for the help with space planes) a shuttle normally has a cargo plane capable of withstanding reentry on one side of the main central fuel tank now the soviet's shuttle had an engine on that tank and this shuttle along with NASA's shuttle has been recreated by the developers NASA's shuttle is the dynawing and the soviet's is the ledstar I think. But anyway then you normally have two SRBs on the sides or four is you are going for a soviet style shuttle.

[AeroGav]

I tinkered more with my design.   I think the lesson is, if it ain't broke , don't fix it.    

I felt that the Nervs mounted ventrally in the wing roots were a cheat,  and wanted to see if i could make the ship work without them bringing our CoM forward.  I also tried getting rid of the extra wing panels that enclosed those engines, since they also brought our CoL forward.

With three nuke engines at the back, which are still lighter than Vectors, and no extra wings, this is how it flies..

In other words it doesn't.     Lift to drag ratio is less than 1.    The problems are

1. small wings for the weight of the vehicle.  Need high speeds, low altitude and high aoa to make lift , which cause excessive fuselage drag
2. CoM well behind the midpoint of the cargo bay, so amount of stuff in cargo bay will affect CG.
3. however, CoL is even further back, so a lot of force is needed to get the nose up to the high AoA needed to make enough lift.
4. number 3 is exacerbated by the short distance between CoM and position of the Elevons.  
5. the big S elevons can generate these forces as they are so powerful, but they create a lot of drag to do so and worse, all that "negative lift" is subtracting from the wings' efforts to keep the plane up

The only reason Vector shuttles fly is brute force - and the NERVs dont have that attribute.

So, I went down to one NERV in place of the Poodle.  Clipping it into the engine mount, you can hardly tell it is there.

The other three main engines will have to be Terriers, for lightness/vacuum ISP.

And a shuttle needs OMS pods doesn't it ?   Again, needing to keep weight down on the rear, i used Sparks. 

This brought CoM forward, but the problem of elevon downforce was still too much.  So,  I angled the stakes up a few degrees, to provide some permanent nose up trim.   The elevons won't need to work so hard.

Finally, and you could argue this is where i lost the plot a bit,  I decided I wanted a bluish tint to my engine plumes.   I got this by clipping ion engines into our sparks and terriers.

https://kerbalx.com/AeroGav/Columbia-IV