Stock Shuttle 1.2 - realism vs flyability?

[AeroGav]

Where do you guys strike the compromise between making stock shuttle-inspired craft look like the real thing vs be easy to fly?

This is my first successful shuttle (gets to orbit with payload, remains controllable).  Unfortunately by the time I was done fixing handling issues, it doesn't look so much like STS anymore 

https://kerbalx.com/AeroGav/Kolumbia

First Change - Vector engines too heavy and screw up the empty CG.      Replace with Terriers

Second change - External tank causing engine thrust to not be inline with CG.   Centre of mass moves up as tank empties.  Solution  - no tank.

Third Up  - With weaker main engines and no External tank,   we need three SRBs to get supersonic/over 10km.  Which also solves the problem of the SRBs not being inline with CG.   With three clustered with 120 degree spacing around the fuselage, everything is in line !

Fourth Prob - It would now fly to orbit, but only when empty.  Most of my LF/O was gone below mach 4, so I installed a pair of Turboramjets and finally it can actually get cargo to space.

Fifth Change - The classic shuttle wing layout has elevons too close to CG for any control authority.  Had to add canards.

Sixth Change - Had to change to a double delta to get enough lift.  TWR on Terriers is too low to just blast up there like a rocket.  Need to fly like an airplane to orbit.

 

Taking the "glass half full" approach

• It has an OMS system based on monoprop and three Puff engines.
• Uses tech appropriate to the shuttle era.    SRB,  LFO main engines,  OMS,  Pratt & Whitney J-58 jet engines.  No  nuclear materials on board.
• Flies like an honest airplane once the SRBs come off.
• CG does not move as the fuel burns off, boosters separate or cargo bay emptied

 

The bad

• You need to be proficient in flying rockets as well as aircraft.   The initial stages under SRB require competence in judging gravity turns (which i am not good at).   The latter stages require airplane skills of maintaining correct AoA and energy/performance management.   Just point the nose somewhere vaguely upward won't do it !
• real shuttle had bigger cargo bay!

 

How do stock shuttles fly then?   I think I made a lot of changes to try get neutral handling qualities,  do other guys just lock one of the autopilot modes and rely on scads of control authority to get it to hold the line?

[KingPhantom]

i try to build them realistic. i fixed the controll problem with enouth SAS parts and puttung the center of thrust through the center of mass. with a little training it's going well.

but i like your desing. i will take a look on that

 

i really love the vector engine for shuttles. but he is late in the tech tree, expensive and heavy... but all my versions with terriers or mainsails on the main tank failed in the classical design. so i had to put weights on the opposite of the shuttle to regain control. its very difficult but awesome if everything works.

[NoobTool]

5 hours ago, KingPhantom said:

i try to build them realistic. i fixed the controll problem with enouth SAS parts and puttung the center of thrust through the center of mass. with a little training it's going well.

but i like your desing. i will take a look on that

 

i really love the vector engine for shuttles. but he is late in the tech tree, expensive and heavy... but all my versions with terriers or mainsails on the main tank failed in the classical design. so i had to put weights on the opposite of the shuttle to regain control. its very difficult but awesome if everything works.

Try moving the tank higher relative to the shuttle and rotating the main engines slightly so that the center of thrust points closer to the center of mass. Having the tank higher means that the center of mass shifts less as fuel is drained from the tank. Also make sure you use mirror symmetry to attach solid boosters to allow you to move them closer to the center of mass. I used the swivel engines on my smallish shuttle design, and while it didn't necessarily look like the real thing, the methodology was pretty close to the real shuttle design.

Edited October 6, 2016 by NoobTool
Typo

[Scientia1423]

If they look like shuttle and can get to space (idk surround it with a cat-ton of boosters and mammoth engines), then it's alright.

Look on scott manley's video on this subject. It's quite old but it still works.