Apologies, it has been a busy week in real life for me.
Technical-wise, it is much improved, more efficient and useful.
Right now the biggest non-clipped payload that can fit is around 30-36t, so that means to reach 10% of the lift-off mass being payload, you need to increase the size of the cargo bay a bit more (
hint: increasing the width by small one block would greatly increasehow much you can fit).
Additionally, you can still make it lighter! That way it doesn't need to carry as much payload to LEO to be efficient. This is a viable alternative if making the payload bay bigger is too hard.
Here's how much fuel it had left after I reached orbit with it:
View attachment 97442
And here's how much was left after a very decent deorbit burn:
View attachment 97443
See that 23%? It's useless because the shuttle is already about to re-enter and land. If you reduce that to 5% by taking off fuel tanks
in the build screen, then the shuttle is lighter, and you don't need to carry as much payload to be efficient.
If you want to keep the extra fuel to go higher than 31km, then just increase the payload bay size so it can use up that extra fuel to carry more payload to 31km.
Additionally, you have 7 probes in your shuttle that are not part of the payload, only used for controlling the shuttle. That's
very heavy, it would be much better if you only had 2 probes, one for the shuttle and one for the door. It will turn more slowly, but that is ok. I understand if you want to keep them to pretend that they are a crew cabin, just pointing out something that you can do.
You have 10 RCS in your shuttle, you only need 4 at most.
If taking off the extra probes and RCS makes your shuttle hard to keep pointed in the right direction on re-entry so that it doesn't burn up, then that means you just need to balance your shuttle.
The easiest way to do that is this:
View attachment 97446
Do you see what I did there?
I separated the forward and back tanks, now they are independent. That's not the only way to do it, it's just an example.
Why is this useful?
Remember I said that you should have 5% of fuel left when you re-entry? With two equally sized tanks in your shuttle, that will say 10% if it is all in one tank.
You can transfer that fuel to the forward tank, or the back tank, so that the shuttle doesn't try to spin and burn up. It's a very cool trick when you practise it.
You can even have balance, some in the forward tank and some in the back tank.
"but wait, that means the engines can't access all the fuel when I'm flying to orbit!!"
Then that just means do this.
View attachment 97447
So to sum up, you need to make it carry 10% of its launch mass in unclipped payload, either by making the payload bay bigger, or the shuttle lighter, or a combination of both. The stuff I just talked about should give you ideas on how to do that, as well as how to deal with any negative effects that happen because of it.