how to make space shuttle?

[Cannon]

seriously, how do you guys design space shuttles, it's never going vertically, there is always more thrust or more mass on one side and of course the whole thing starts turning on that side.

[Slam_Jones]

You may want to install a mod that would display some extra numbers regarding your vessels. I recommend Kerbal Engineer.

I haven't done many shuttles myself, but I know one of the most important values is the Thrust Torque. Basically, if your vessel has 0 thrust torque, it will fly perfectly vertical. The higher the thrust torque, the more the engines want to spin the ship, rather than push it straight ahead.

You can try angling the engine on the shuttle itself, as I've seen many successful shuttles do that. Off-setting and rotating the engines are two ways to change the thrust torque. Play around with it, and try to get it as low as possible.

Good luck

[Cannon]

You may want to install a mod that would display some extra numbers regarding your vessels. I recommend Kerbal Engineer.

I haven't done many shuttles myself, but I know one of the most important values is the Thrust Torque. Basically, if your vessel has 0 thrust torque, it will fly perfectly vertical. The higher the thrust torque, the more the engines want to spin the ship, rather than push it straight ahead.

You can try angling the engine on the shuttle itself, as I've seen many successful shuttles do that.

Good luck

i tried angling it but as soon as the fuel barrles are separated, shutle itself is spinning because of that

[SAI Peregrinus]

None of the engines in stock KSP have the gimball range that real Shuttle main engines have. That makes things a LOT harder.

[cantab]

Something to keep in mind is that with the real Space Shuttle the Orbiter weighed about a hundred tonnes, while the entire stack was two thousand. So it was a small payload on the side of a big rocket. In KSP you often end up the other way round, making life hard.

[GoSlash27]

Cannon,

Shuttles are hard. *Seriously* hard.

There are a lot of weird design tricks to making them, but you will figure them out on your own.

The #1 most important thing to burn into your brain is this: Your engines must not thrust "forward". They must thrust through the center of mass.

As you have already noticed, failure to do this will make shuttles that tumble and crash.

Find your center of mass. Find where it will be when you're full on the pad and where it is when you're empty just short of orbit. Track where it moves throughout the flight. Design accordingly so that your center of thrust is always pointing through it in every stage of the flight. Not only do you have to design so that your engines thrust through the center of mass, but you also have to design so that your center of mass moves in a straight line towards the engines as the fuel drains.

If you sort this out, the rest is easy.... sorta. Shuttles are difficult to fly even when they're perfectly balanced.

Study the first pic: The engines are all splayed out instead of pointed the same way. They converge at the center of mass. They must *always* converge at the center of mass.

Everything pushing through center of mass

The SRBs were offset a hair inboard, so even without them the SSMEs are still pushing through center of mass.

The center of mass travelled inboard and aft throughout the flight, so even with the empty tank the engines kept alignment. But...

Without the tank, the center of mass shifts way inboard. Accordingly, the OMS engines must be aligned through the new center of mass.

Success!

The center of mass is everything in shuttles.

Good luck!

-Slashy

/ have I mentioned the center of mass?

Edited August 22, 2015 by GoSlash27

[Alshain]

First, You are not going to be able to do it with a single engine on the shuttle. You need to be able to aim the bottom row and the top row of engines seperately. One engine makes it hard to balance

Second, take the engine off the main fuel tank, that's just silly looking and it is going to end up too much thrust.

Third, the shuttle doesn't need that much fuel, it feeds from the tank it's mounted on. The real shuttle uses OMS once in space it doesn't fire the main engines again so it needs no LOX at all, if you want you can use the O-10's for that role and carry only monoprop. However, carrying LOX works too, but that is a lot, you only need enough to change orbits and rendezvous.

Fourth, the orange tank is a poor choice for a Mk3 Shuttle. I know, the orange seems like it would be perfect, but it isn't. You want the bigger 3.75m parts. Look at the real thing, compare the size of the bird to it's tank and boosters. You just need more fuel there.

Finally, put the boosters angled in just a little so they are centered on the CoM. Make sure you have sepatrons to clear them from the wings though.

Edited August 22, 2015 by Alshain

[Reactordrone]

You can also avoid thrust asymmetry by going dyna-soar style.

[Alshain]

You can also avoid thrust asymmetry by going dyna-soar style.

http://img.photobucket.com/albums/v499/swampmonster/Kerbal%20space%20program/screenshot355_zpssfj69hdm.jpg

That can be pretty hard too because the wings bring the center of lift forward. Another option I've seen done is mounting the fuel to the nose, but still a vertical rocket. That keeps the wings at the back.

[nuclearping]

It's about the most difficult thing that you can build and launch in KSP. It can be done, but it's very tricky.

[...]

Expect a LOT of throttle feathering/balancing work.

This. But it is alot of fun too. After you passed the learning curve tho.

Interestingly I'm also messing around with Shuttles at the moment and found that thread searching for inspirations.

My key to success is "Infernal Robotics" to counter the COM / COL issues.

And yes, it involves ALOT of fiddling around and adjusting the servo for the main engine. Especially after the Boosters are burned out. You have to stop throttle and turn the main engine hinge like 45° up.

I already thought about using kOS to automatically adjust the main engine hinge according to the changing COM / COL due to fuel loss.

Here are some screenshots of my current Minmus Polar Satellite Contract Mission:

[Xavven]

That can be pretty hard too because the wings bring the center of lift forward. Another option I've seen done is mounting the fuel to the nose, but still a vertical rocket. That keeps the wings at the back.

Yeah, I tried that once and got immediate flipping, and that was in .90!

So I looked up "dyna-soar" and found this artist's conception of the dyna-soar on a Titan booster on Wikipedia. To counter the high Center of Lift, the artist added giant fins to the back.

https://en.wikipedia.org/wiki/Boeing_X-20_Dyna-Soar#/media/File:Dyna-Soar_on_Titan_booster.jpg

[ajburges]

OTOH unaligned thrust throws perfectly good ISP away via cosine losses.

Ideally, we would have the parts to do the following:

> An engine (array) large enough for good TWR after SRB sepperation.

> SRBs large enough for both 1.2-1.4 craft TWR at launch and enough burn time to realize greater than unity TWR after sepperation.

> A single tank large enough for about 2 km/s dV for the main engine.

> Better aerodynamic parts for angled main engines.

Both the SRBs and tanks are a little small for a Mk3 shuttle. Mk2 parts are better for SSTOs.

[Cannon]

Damn, no wonder it's retired

[GoSlash27]

OTOH unaligned thrust throws perfectly good ISP away via cosine losses.

True, but it is necessary. You can't build a crooked rocket without having crooked thrust.

You've got all the fuel on one side and all the engines on the other. You ain't goin' to space if you don't account for that fact.

Best,

-Slashy

[Red Iron Crown]

I sidestepped the thrust asymmetry issue when building a craft with shuttle-style staging:

It's so much easier (and more efficient, too!). Not really suitable for a replica of the real STS, but if you just want the equivalent capabilities it works really well.

[Tex_NL]

I sidestepped the thrust asymmetry issue when building a craft with shuttle-style staging:

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

https://dl.dropboxusercontent.com/u/61004449/KSP/1.0.4/screenshot840.png

https://dl.dropboxusercontent.com/u/61004449/KSP/1.0.4/screenshot843.png

It's so much easier (and more efficient, too!). Not really suitable for a replica of the real STS, but if you just want the equivalent capabilities it works really well.

I launch all my shuttles like that and have been doing so for over a year.

Tip: Place an escape tower on the tip of your nose tank. It will pull away the tank when empty.

[Red Iron Crown]

Why didn't I think of that? Rep for you for that good tip.

[moogoob]

I take a similar approach to Red Iron Crown, just with the boosters dorsal and ventral and without the nose fuel - the shuttle itself is light enough that the onboard tanks and fuel in the boosters are enough.

Javascript is disabled. View full album

[The_Rocketeer]

Need a little help stabelizing stock Space Shuttle

I've now made several NASA STS replicas, with varying success and performance. The short answer is, it's a total ball-ache and it's much easier to get other types of craft with similar or superior capabilities into orbit by other means. On the other hand, if a STS replica is what you really want to do, eventual success is massively rewarding. My last/best refined version is excellent, carries payloads up to a full Jumbo tank, but still has a totally unique flight profile and staging sequence compared to a rocket.

Lastly, fuel mass trimming during flight is a red hot tip.

Edit: I just realised the thread I linked dates from before the Mk3 overhaul. My newer shuttles use the updated Mk3 parts, with 3x Mainsail, 2x S1 SRBs, and 3x S3 14400 tanks for the ET. It also has 2x Swivels for OMS with their own FL-T400 tanks which are not used during take-off.

Edited August 22, 2015 by The_Rocketeer

[Red Iron Crown]

I've done the over/under booster thing, too:

I like the inline version better because I get to recover the expensive lifter engine, but the orbiter in this design is longer range. It's a tradeoff, I suppose.

[Snikersnee]

In real life the shuttle had three liquid fuel engines pointing slightly inward to counteract its weight. During retro burn, this would cause the spacecraft to flip, so there were two liquid fuel engines "on top" to counteract the rotated main engines. Have a look-see:

https://www.awesomestories.com/images/user/c80006be2e.gif

https://en.m.wikipedia.org/wiki/Space_Shuttle_Orbital_Maneuvering_System

[Red Iron Crown]

The main engines were never used for retro burns on the real Space Shuttle, it carried no fuel for them. Once the external tank was jettisoned it was the smaller, hypergolic-fueled OMS engines only.

[GoSlash27]

^ What RIC said. The SSMEs were pointed down because the center of mass was ahead of and below the orbiter during launch. Once the tank was jettisoned, the SSMEs were just along for the ride. The OMS engines weren't there to "balance" the SSMEs, they were the sole source of thrust for all orbital maneuvers, including retro burn. Accordingly, they were aimed through the orbiter's center of mass.

Best,

-Slashy

[GoSlash27]

Some additional pics to show the alignment:

SRBs and full tank. Red lines are the direction of thrust. Black & yellow sphere is center of mass.

Full tank, SRB jettison

Empty tank

Tank jettison, OMS engines

Reentry & landing, no payload

Best,

-Slashy

Edited August 22, 2015 by GoSlash27

[Kelderek]

Second, take the engine off the main fuel tank, that's just silly looking and it is going to end up too much thrust.

It's funny, it took me a couple decades and dozens of shuttle launches before I realized that there was no engine on the "big orange thing" and that it was just a big fuel tank. I guess I just assumed it had one, I never scrutinized the space shuttle design close enough. I love the space shuttle design, I find it very fascinating what they came up with and how well it worked for so many flights.