Piggy-back a space plane on a rocket

[Pvt. Stash]

Does anyone know a good tutorial on how to do this? I'm trying to use a US Space Shuttle type launch. I keep having problems with control on liftoff no matter how large I make the base lifting mechanism.

https://upload.wikimedia.org/wikipedia/commons/2/2a/Space_Shuttle_Atlantis_launches_from_KSC_on_STS-132_side_view.jpg

Thanks!

[Pvt. Stash]

I always use mechjeb on launch. It still can't keep control of my ships when constructed like the screenshot. I can build massive lifters, asparagus-staging, and even get into orbit fine without mechjeb. I just can't seem to get this kind of lifter to work correctly.

[Rhedd]

Space shuttles are extremely difficult to launch. The real one wouldn't have been possible without computer-controlled, highly gimballed engines.

The problem is essentially that the line of thrust is so far off from the center of mass, and the center of mass is going to change through the whole flight.

Note the way in your picture the shuttle's three engines are pointing at a very sharp angle toward the tail. Keep in mind that although you can't really tell in that picture, the three engines ARE at full throttle and pushing along with the SRBs. That angle is the only thing keeping the shuttle from doing a backflip, which I suspect is what yours is doing.

In 1.1 Squad added a shuttle-type engine with a very wide gimbal ability, but I haven't used it so I can't recommend it. That's the sort of thing you're going to need, though, if you want to do this sort of launch.

Like I said, don't feel bad. It's stupid hard to engineer such a vessel so it works.

[Pvt. Stash]

Originally posted by Rhedd:

Space shuttles are extremely difficult to launch. The real one wouldn't have been possible without computer-controlled, highly gimballed engines.

The problem is essentially that the line of thrust is so far off from the center of mass, and the center of mass is going to change through the whole flight.

Note the way in your picture the shuttle's three engines are pointing at a very sharp angle toward the tail. Keep in mind that although you can't really tell in that picture, the three engines ARE at full throttle and pushing along with the SRBs. That angle is the only thing keeping the shuttle from doing a backflip, which I suspect is what yours is doing.

In 1.1 Squad added a shuttle-type engine with a very wide gimbal ability, but I haven't used it so I can't recommend it. That's the sort of thing you're going to need, though, if you want to do this sort of launch.

Like I said, don't feel bad. It's stupid hard to engineer such a vessel so it works.

That is exactly what's happening. The thing gets to a few hundred feet and then flips.

I'm probably using the wrong engines then. I've been trying with standard heavy lifters like you would use to launch large satellites. Any idea what the name of the engine is?

[Rhedd]

Originally posted by Pvt. Stash:

That is exactly what's happening. The thing gets to a few hundred feet and then flips.

I'm probably using the wrong engines then. I've been trying with standard heavy lifters like you would use to launch large satellites. Any idea what the name of the engine is?

I'm afraid not, and I have way too many mods to find it.

I do know that if you look at a real SS engine, you'll note that it's ribbed and has a number of pipes on the nozzle. Squad built theirs to look the same, so just look for the one that LOOKS like a SS engine, and check it's gimbal to be sure.

Or, you could do what I do and go all 1950's Verner von Braun, and launch them like this:
http://steamcommunity.com/sharedfiles/filedetails/?id=684142968
It's a lot of fun, and if you look you can find a LOT of old NASA concepts that considered doing it this way.

[Gamer]

I made one like that, basically i loaded the spaceplane in the VAB, rotated it so it would face the right way, placed a decoupler on the bottom and attached the major booster from that. But you NEED a counterweight that weighs similar to the spaceplane otherwise it will always tip. Something with a similar weight like a liquid fuel tank.

[Pvt. Stash]

Originally posted by ich bin heute:

idk ooooooooooh add me watch me bulid i cant land worth a ♥♥♥♥ doe

I'm really sorry i went AFK during the session. My kid had a bathroom accident and I had to give her a bath. Thank you so much for your willingness to help.

Sorry again.

[Pvt. Stash]

Originally posted by Rhedd:

Originally posted by Pvt. Stash:

That is exactly what's happening. The thing gets to a few hundred feet and then flips.

I'm probably using the wrong engines then. I've been trying with standard heavy lifters like you would use to launch large satellites. Any idea what the name of the engine is?

I'm afraid not, and I have way too many mods to find it. :KSmiley:

I do know that if you look at a real SS engine, you'll note that it's ribbed and has a number of pipes on the nozzle. Squad built theirs to look the same, so just look for the one that LOOKS like a SS engine, and check it's gimbal to be sure.

Or, you could do what I do and go all 1950's Verner von Braun, and launch them like this:
http://steamcommunity.com/sharedfiles/filedetails/?id=684142968
It's a lot of fun, and if you look you can find a LOT of old NASA concepts that considered doing it this way.

LOL YES! That's how I've been launching my small space planes, but I was going for the next level and trying to challenge myself.

Thank everyone for their tips and help!

[Rhedd]

Originally posted by Tonald Drump:

I made one like that, basically i loaded the spaceplane in the VAB, rotated it so it would face the right way, placed a decoupler on the bottom and attached the major booster from that. But you NEED a counterweight that weighs similar to the spaceplane otherwise it will always tip. Something with a similar weight like a liquid fuel tank.

It's not really the weight that's the problem. Rockets can be extremely top-heavy and still fly. It's those darned wings on the shuttle! I never put fins on anything, ever (they're totally unnecessary on a well-made vessel), but I instantly saw that von Braun was right in putting giant fins on the bottom of that thing! Those four huge delta wings on the bottom are absolutely necessary.

Or, I could just say your rocket flips because you'e Donald Trump, so everything you do turns out a$$-backwards. :P

[El Rushbo]

My space shuttle efforts involved having a large engine on the lifter tank (KR2L) and scaling the throttle limiter to maintain balance during ascent. Having a number of vernor engines on the tank can also help counter the shift and buy you a little time, also they'll serve as an indicator if you need to change the engine throttle. I always paid close attention to the PYR indicator in the lower left corner, as the pitch indicator shifted, I would adjust the thrust limiter to keep it centered.

[Azunai]

you should probably use the vector engines for a space shuttle replica. they have a HUGE gimbal range and decent thrust. i'm pretty sure they were added to the game specifically for spaceshuttle-like craft.

take a look at the stock space shuttle that comes with the game. it uses a pair of vectors and it's controllable enough to get to orbit. flies like a skyscraper, but you can brute force it into a gravity turn with some effort and the main reason why it works is the gimbal range of the vector engine.

[SievertChaser]

Vectors ARE the in-game copy of the SSMEs. Be sure to rotate them by 10 degrees so that the gimbal has maximum pitch authority.

[Panda]

I was testing this in sandbox the last time I played and it really wasnt as had as one would think it would be.

As long as you have both the booster and shuttle engines running at launch you wont start spinning wildly out of control like some of my earlier tests.

My shuttle lifters always had a tendency to start to lean a lot after several hundred feet in the direction the shuttle was mounted on, my solution was to face the whole thing so the shuttle would lean in the direction of the gravity turn. The shuttle's wings would keep it steady long enough to get out of atmosphere (although technically flying upside down, but I would turn it in upper atmosphere)

[SievertChaser]

Originally posted by Panda:

My shuttle lifters always had a tendency to start to lean a lot after several hundred feet in the direction the shuttle was mounted on, my solution was to face the whole thing so the shuttle would lean in the direction of the gravity turn. The shuttle's wings would keep it steady long enough to get out of atmosphere (although technically flying upside down, but I would turn it in upper atmosphere)

The real-life shuttle launches upside-down. AFAIK the Energiya-Polyus, with an inert payload strapped to the side of the booster, did the same.

[AlexMBrennan]

I'm trying to use a US Space Shuttle type launch

How much do you care about the aesthetics? Obviously it would be a lot easier if you used two smaller symmetric tanks attached to e.g. the wings instead of a single tank attached to the shuttle's belly.

[SievertChaser]

Originally posted by AlexMBrennan:

I'm trying to use a US Space Shuttle type launch

How much do you care about the aesthetics? Obviously it would be a lot easier if you used two smaller symmetric tanks attached to e.g. the wings instead of a single tank attached to the shuttle's belly.

Well, you can pass that a historic recreation too.
http://www.aerospaceprojectsreview.com/blog/wp-content/uploads/2013/05/Phase-B-system-study.jpg