Space Shuttles are harder than SSTOs

[Mastikator]

So I decided to try and build a space shuttle, this is a lot harder than a spaceplane. The main difficulties with a SSTO is center of mass vs center of lift, drag and just having anything left after you circularize.
With a space shuttle it was a almost impossible to get it balanced, as you see I had to split the tanks up and put one on the back, the tanks were more than enough to get me into orbit, the main mission of this is just to collect one kerbal in LKO, but it easily has enough juice to put satellites into space and it has room for 5 kerbals + pilot.

This was my first attempt at a space shuttle. The vector are awesome for this. 1000kn thrust at 1.25m size AND good Isp at sea level.

[URL="http://images.akamai.steamusercontent.com/ugc/404558024709515411/FB17F50F4F02FE86227DF2693AEBA29E9892A8B5/"]In space[/URL] and [URL="http://images.akamai.steamusercontent.com/ugc/404558024709518307/C3B324A46B503A339D64FD8B6FE5BA13082056C6/"]in the VAB[/URL]
With a 59k/74k return value, not quite as economic as an SSTO spaceplane

This thing was an absolute mess to get into orbit, the fuel kept draining from the upper tanks first, which put it way off balance so I had to transfer while the flames were still on.

I also noticed that it matters where you place the fuel ducts. When I placed the fuel duct for the front tank on the crew compartment the fuel on the back drained first, when I put it on the tank they drained simultaneously.

It would probably be easier to fly if it had a cargo full of heavy stuff though, the TWR was very high all the way through.

[paul23]

Uh the "vectors" in a space shuttle hardly provide any lift at sea level - the main lift is from the main engine, the "vectors" in the space shuttle only act to stability the craft. Also to get the right center of gravity/mass in the early phase much more close to the main tank than a mainsail/orange tank will give you, think more like the large kerobdyne tank/engine.

[Mastikator]

[quote name='paul23']Uh the "vectors" in a space shuttle hardly provide any lift at sea level - the main lift is from the main engine, the "vectors" in the space shuttle only act to stability the craft. Also to get the right center of gravity/mass in the early phase much more close to the main tank than a mainsail/orange tank will give you, think more like the large kerobdyne tank/engine.[/QUOTE]

Vectors have Isp 295s at sea level 936kn thrust, Isp 315s in vacuum and 1000kn thrust. Even the aerospikes have only 290s Isp at sea level (and 340 in space)

The vectors also have 25 TWR, which (if I'm not mistaken) is the highest of all the thrusters.

Edit-
[IMG]http://images.akamai.steamusercontent.com/ugc/404558024709668241/203FDB3EDEDE43F24E96335C7C059BF3CFFB7C1D/[/IMG] Edited November 18, 2015 by Mastikator

[ZooNamedGames]

I don't know what paul is getting at, but your going at this all wrong.

Your using ONLY vectors as your ONLY thrust through the entire mission. A real shuttles uses a mix of SRBs and the main engines to get into orbit and even then it doesn't use them for the entire mission. Once in or near orbit the shuttle uses its OMS engines which in KSP standards are monopropellant engines.

I suggest removing that silly tank on your tail fin and add SRBs for early thrust. I also suggest maybe upgrading to mk3... Might work better for you since the vectors were made for the intention of use on the mk3. Yes I know that the 2.5m are small in comparison to the mk3 parts, but they still work.

The SRBs should provide initial thrust in the beginning, but after 100m/s you will have enough speed to stabilize. As the SRBs burn out your TWR of the vectors become that much more important. The gimbal comes into play when your SRBs are gone and you need to adjust for the moving CoM in your ET.

I can explain further but this should be enough for now. If you want me to explain more, let me know. I can provide a step by step walk through for you if you ever need it.

[Pecan]

Yes, that's what everyone has always said about shuttles in KSP.

[GoSlash27]

^ What he said. Shuttles are about the hardest thing you can make in KSP. Best, -Slashy

[ZooNamedGames]

I'm still offering help if you want it.

[Mastikator]

[quote name='ZooNamedGames']I'm still offering help if you want it.[/QUOTE]

I actually tried taking your advice but the VAB started bugging out, it clicking with the mouse stopped working, I couldn't do anything, not even leave the VAB so I just gave up. It was looking promising until KSP gave up on me though.

[Red Iron Crown]

Since you don't mind messing with the classic STS layout, you might try either of these approaches.

Put the tank on the nose and suddenly it gets much easier:

[IMG]https://dl.dropboxusercontent.com/u/61004449/KSP/1.0.4/screenshot838.png[/IMG]

Or sandwich the spaceplane part between two tanks:

[IMG]https://dl.dropboxusercontent.com/u/61004449/KSP/1.0.4/screenshot820.png[/IMG]
(This one has a lightweight rocket for the shuttle engine, you could replace with vectors and eliminate the fuel tank motors that get discarded.)

[ZooNamedGames]

[quote name='Mastikator']I actually tried taking your advice but the VAB started bugging out, it clicking with the mouse stopped working, I couldn't do anything, not even leave the VAB so I just gave up. It was looking promising until KSP gave up on me though.[/QUOTE]

Well try again.

Note to use radial x1 symmetry for the ET. Design the orbiter like an aircraft as it will be. Then add the ET, then use x2 radial placement to add your two SRBs and then continue.

Idk why KSP bugged out but it doesn't mean my logic is bugged.

[Mastikator]

[quote name='ZooNamedGames']Well try again.

Note to use radial x1 symmetry for the ET. Design the orbiter like an aircraft as it will be. Then add the ET, then use x2 radial placement to add your two SRBs and then continue.

Idk why KSP bugged out but it doesn't mean my logic is bugged.[/QUOTE]

I didn't mean to say your logic was wrong, I thought it was good advice. I was just annoyed that I didn't get to try it out because of KSP buggyness.

[Xyphos]

if you download FAR, (but installation isn't required) it includes a well-made and easy-to-fly shuttle in the zip file.
my jaw dropped to the floor when I saw this ship, whoever made it is clearly a professional-grade KSP ship builder :D

[ZooNamedGames]

[quote name='Mastikator']I didn't mean to say your logic was wrong, I thought it was good advice. I was just annoyed that I didn't get to try it out because of KSP buggyness.[/QUOTE]

Oh ok. Well have more advices :) I love giving it.

[COLOR="silver"][SIZE=1]- - - Updated - - -[/SIZE][/COLOR]

[quote name='Xyphos']if you download FAR, (but installation isn't required) it includes a well-made and easy-to-fly shuttle in the zip file.
my jaw dropped to the floor when I saw this ship, whoever made it is clearly a professional-grade KSP ship builder :D[/QUOTE]

How big is it? I haven't even seen it and I can guess who the owner might be.

[Red Iron Crown]

The stock Slim Shuttle that was added in 1.0.5 is pretty good, too.

[wumpus]

If the "problem" is that Shuttles are harder than spaceplanes (or at least jet-based SSTOs), then the "solution" is to download the real solar system mod[collection]/overhaul. You can find all sorts of reasons why the shuttle was a bad idea over in the science forums, but the reason that there aren't a lot of spaceplane SSTOs on Earth is that Kerbin has an orbital velocity close to the speed jet engines can produce. Earth's is waaaay more than that.

[ZooNamedGames]

[quote name='wumpus']If the "problem" is that Shuttles are harder than spaceplanes (or at least jet-based SSTOs), then the "solution" is to download the real solar system mod[collection]/overhaul. You can find all sorts of reasons why the shuttle was a bad idea over in the science forums, but the reason that there aren't a lot of spaceplane SSTOs on Earth is that Kerbin has an orbital velocity close to the speed jet engines can produce. Earth's is waaaay more than that.[/QUOTE]

He's referring to stock...

Moreover, I can explain to him why the space shuttle was an amazingly stupid, yet effective peice of space hardware, but I'm not since he doesn't want to know why, he wants to know how.

[wumpus]

[quote name='ZooNamedGames']He's referring to stock...
[/QUOTE]

Yes, but since the first page covered how to fix his shuttle (do what both the actual* shuttle did and get pulled into space by the SRBs). And I'm still impressed by how big an issue that scaling Kerbin down by a factor of 10 really is (and how Squad makes it seamless). I figured they left out an obvious fix for jets/turbofans (other than the issue of being ripped to shreds once they exceed maximum air velocity), because spaceplanes are cool and fun to make, but the problems appear deeper than that.

The answer why *stock* KSP makes it easier to fly spaceplanes than shuttles is that jet engines can reach nearly orbital velocity on Kerbin, but not Earth. The reason that jet engines are not scaled down is that they would need to be scaled down by a factor of 10 or so, and then wouldn't lift off at all (I'm assuming that the throttle is linear to thrust: swapping weasly for jumbo jets on the mallard *just* barely got the plane off the runway, but left me scrambling for every m/s for the next several kms, and never seemed to get above 100m/s *or* 50m of altitude). The scaling KSP uses to make orbiting easier and faster has some weird side effects, and one of them is that spaceplanes are easy. Shuttles, on the other hand don't make much more sense on Kerbin than they did on Earth (even though refurbishing the whole thing isn't required).

Why a factor of 10? My understanding is that air resistance at minimal speeds is linear. Once you hit turbulence (bicycle speeds) it goes quadratic. Over the speed of sound it goes to cubic powers. So to halve the speed you need to lower the power by a factor of eight (rounded to 10, and half probably isn't nearly enough). While this is suspiciously similar to horsepower vs. speed on wheels, it gets there by different means.

* For Soviet values of shuttle, I think it was hauled into space by liquid boosters. The shuttle's on-board engines (presumably had some if only for circularization), were even less important.

[GoSlash27]

The STS orbiter design is just about the most challenging thing you can make in KSP, but it *can* be done.
[spoiler=Flight of the Kolumbia]
[img]http://i52.photobucket.com/albums/g13/GoSlash27/KSP/Shuttle%20Kolumbia/Kolumbia3_zpsoqjhrbzn.jpg[/img]
[img]http://i52.photobucket.com/albums/g13/GoSlash27/KSP/Shuttle%20Kolumbia/Kolumbia4_zpsgi3jggmx.jpg[/img]
[img]http://i52.photobucket.com/albums/g13/GoSlash27/KSP/Shuttle%20Kolumbia/Kolumbia5_zpsfln9bmvl.jpg[/img]
[img]http://i52.photobucket.com/albums/g13/GoSlash27/KSP/Shuttle%20Kolumbia/Kolumbia6_zps3qoaqaq9.jpg[/img]
[img]http://i52.photobucket.com/albums/g13/GoSlash27/KSP/Shuttle%20Kolumbia/Kolumbia1_zps93bloi7l.jpg[/img]
[/spoiler]

I've been making stock shuttle replicas since KSP 1.0, and it's never gotten any easier. Even with the new "Vector". Keep at it, though. It's a good learning experience and you get a real sense of accomplishment when you make it work.

Best,
-Slashy

[Guest]

[quote name='Mastikator']So I decided to try and build a space shuttle, this is a lot harder than a spaceplane.[/QUOTE]What did you expect? Kerbin has half the atmosphere height of Earth, roughly 28% the orbital velocity, and the jet engines in KSP are ridiculously overpowered [i]even after their recent nerf[/i]. Space Shuttles are an engineering balancing act, spaceplanes are airplanes with rocket engines.

[Alshain]

Tip:

The shuttle blasts off, rolls over mid-flight and ascends upside down. Many people don't realize that, I guess because it is hard to see when it does it.
[url]https://youtu.be/OnoNITE-CLc?t=2m10s[/url]

The SSME needs to point at the planet for the best efficiency, if it points away from the planet you are actually thrusting the wrong way. Edited November 18, 2015 by Alshain

[Xyphos]

[quote name='regex']spaceplanes are airplanes with rocket engines.[/QUOTE]

once in space, everything is a rocket.

[Alshain]

[quote name='Xyphos']once in space, everything is a rocket.[/QUOTE]

Well, except everything that isn't :P