How do I make a space shuttle?

[Raven.]

On 2/8/2017 at 11:01 AM, Alpha 360 said:

I am stumped at making a space-shuttle, all I know is vectors, orange fuel tank, kickbacks, and Mk3 parts, but it tried continually and failed continually. Any help?

Not easily. But there are several little dirty secrets to building shuttles. For one, the main engines on the shuttle itself needs to be a high gimbal engine so it can adjust the thrust vector as the main fuel tanks depletes. The second is that these main engines need to be at a 5 to 20 degree angle in order to account for the asymmetric thrust. 

But for me, the hardest part of a shuttle was not building nor was it getting it into orbit. It was landing the darn thing when there's no fuel left. And this part takes practice.

[AeroGav]

The problems with KSP shuttles

1. the  real SRBs comprised 55% of the total launch mass of the shuttle stack, and supplied over 80% of the thrust.  Their skinny appearance belies the much higher density of their propellant vs the liquid hydrogen in the external tank.

2. The external tank was a bit over 35% of the total launch mass.

3. The orbiter itself is less than 10% of the mass of the tank/booster stack it rides on, and only has 20% of the takeoff thrust.  By comparison a Kerbal shuttle with 2 kickbacks and 3 vectors will have 75% of the thrust  in the orbiter, well above the stack's CoM.

4. The real SSMEs weighed 3.5 tons .  That's a little lighter than the Vector,  but the main difference is that the real orbiter is more than twice the weight (70 tons) of a Kerbal one constructed with an identical appearance.    So, they are a lower portion of the vehicle's weight and having them at the back of the fuselage doesn't mess with the CoM so badly.

 

Anyway....  back to practicalities.

Someone linked how it was easier to put the external tank at the front of the shuttle and keep it in line with the CoM.

Fair enough, that keeps with the Shuttle concept of "keep the engines, throw away the tank".

Your vehicle cannot SSTO with a reasonable payload fraction, it cannot carry everything to orbit.  However, in KSP,  the recovery value, per KG of dead weight, is actually lower for many liquid engines than it is for their fuel tanks.

In other words, you should keep the tank, and throw away the engines.

So, design the orbiter with fuel tanks comprising part of the fuselage.

A single NERV (on the mk3 mount's center attach node) and three sparks (on the vector nodes) can be your upper stage / OMS propulsion.  This is an efficient but light powerpack that weights less than one vector and no more than the cockpit, it keeps your CoM nicely amidships.      A CRG50 can go in the middle of the fuselage with a short mk3 rocket fuel tank ahead of and behind it.  The wings can strakes can hold LF for the NERV.

The Middle stage - Reliant engines can cluster around the wings or fuselage in a way that keeps everything nicely balanced.   As you get light enough and high enough not to need their power stage them off.

Lower stage - Some SRBs to assist takeoff.   Again, rather than hanging two under the orbiter, cluster three or four around the orbiter radially, so they produce no torque.

 

[Alpha 360]

Thanks for everyone posting on this topic. Just so everyone knows,I managed to make a usable shuttle using stock parts and the basic, standard set up, it is possible to make a shuttle with only two kickbacks, three vectors, two orange tanks and Mk3 parts without too much difficulty. 

Edited February 11, 2017 by Alpha 360
"Kouston, we have several problems, but that doesn't matter so we want to continue on with the mission."

[AeroGav]

18 hours ago, AeroGav said:

The problems with KSP shuttles

1. the  real SRBs comprised 55% of the total launch mass of the shuttle stack, and supplied over 80% of the thrust.  Their skinny appearance belies the much higher density of their propellant vs the liquid hydrogen in the external tank.

2. The external tank was a bit over 35% of the total launch mass.

3. The orbiter itself is less than 10% of the mass of the tank/booster stack it rides on, and only has 20% of the takeoff thrust.  By comparison a Kerbal shuttle with 2 kickbacks and 3 vectors will have 75% of the thrust  in the orbiter, well above the stack's CoM.

4. The real SSMEs weighed 3.5 tons .  That's a little lighter than the Vector,  but the main difference is that the real orbiter is more than twice the weight (70 tons) of a Kerbal one constructed with an identical appearance.    So, they are a lower portion of the vehicle's weight and having them at the back of the fuselage doesn't mess with the CoM so badly.

 

Anyway....  back to practicalities.

Someone linked how it was easier to put the external tank at the front of the shuttle and keep it in line with the CoM.

Fair enough, that keeps with the Shuttle concept of "keep the engines, throw away the tank".

Your vehicle cannot SSTO with a reasonable payload fraction, it cannot carry everything to orbit.  However, in KSP,  the recovery value, per KG of dead weight, is actually lower for many liquid engines than it is for their fuel tanks.

In other words, you should keep the tank, and throw away the engines.

So, design the orbiter with fuel tanks comprising part of the fuselage.

A single NERV (on the mk3 mount's center attach node) and three sparks (on the vector nodes) can be your upper stage / OMS propulsion.  This is an efficient but light powerpack that weights less than one vector and no more than the cockpit, it keeps your CoM nicely amidships.      A CRG50 can go in the middle of the fuselage with a short mk3 rocket fuel tank ahead of and behind it.  The wings can strakes can hold LF for the NERV.

The Middle stage - Reliant engines can cluster around the wings or fuselage in a way that keeps everything nicely balanced.   As you get light enough and high enough not to need their power stage them off.

Lower stage - Some SRBs to assist takeoff.   Again, rather than hanging two under the orbiter, cluster three or four around the orbiter radially, so they produce no torque.

 

Something like this possibly?    Is it still a shuttle with horizontal takeoff?   

Two kickbacks

Two Reliants

5 sparks

1 NERV

2 ext tanks

2k delta v remaining with payload in orbit

 

[AeroGav]

I present, a more tweaked version of the "Full Kerbal" shuttle above.  Launch cost is 16,314 Funds in non-recovered hardware.

4 Hammers are the first stage of booster (recovered with chute) and they have aux LFO tanks on them to feed the main engines during t/o

2 Thumpers get us to 5km and mach 0.86 (not recovered)

2 external tanks on the wingtips, and 2 reliant booster engines.

Easy to fly, for a shuttle as everything is in line with CoM

https://kerbalx.com/AeroGav/Baby-Shuttle-Block-2