How can I get this 142.8 ton behemoth into orbit?

[ImperialistPigDog]

every rocket I strap this thing to keeps toppling over. What's a good way to build ascent stages for huge craft?

 

[swjr-swis]

Weight should not be the issue, I've put things 5 times that weight into space with stock 1.0.5, and I've seen heavier payloads than that too. So it's about handling the CoM and aerodynamics.

My first instinct would be to build a 'pull' frame around it, rather than the usual push lifters - point the bow up, and assemble a wide circle of heavy lifter boosters around it that ultimately decouple from the top/bow of your craft.

I see the back of either a BZ-52 radial attachment point or a Clamp-o-Tron docking port sticking out the bow about center-way between the two I-beams. If that is offset to be above the CoM when the craft is rotated bow-up, that can serve as the pull-point for the booster assembly (or if you are more comfortable doing it traditional push-style, point the bow down and build as a conventional payload).

It's not easy to tell from just the pictures, but I think the large fairing should about be wide enough on it's widest to envelop the craft and simplify the aerodynamics. It'll need strutting, but that's not hard to do. In the pull frame design, place the fairing upside down from top to bottom.

If the CoM is not aligned well and offsetting that BZ-52/docking port on the bow is not an option, you can add a bit of strategically placed disposable mass on a decoupler to bring the CoM where it needs to be.

I don't expect it to be very problematic at all. Is the craft file available somewhere, for us to have a try at assembling a lifter?

[ImperialistPigDog]

47 minutes ago, swjr-swis said:

Weight should not be the issue, I've put things 5 times that weight into space with stock 1.0.5, and I've seen heavier payloads than that too. So it's about handling the CoM and aerodynamics.

My first instinct would be to build a 'pull' frame around it, rather than the usual push lifters - point the bow up, and assemble a wide circle of heavy lifter boosters around it that ultimately decouple from the top/bow of your craft.

I see the back of either a BZ-52 radial attachment point or a Clamp-o-Tron docking port sticking out the bow about center-way between the two I-beams. If that is offset to be above the CoM when the craft is rotated bow-up, that can serve as the pull-point for the booster assembly (or if you are more comfortable doing it traditional push-style, point the bow down and build as a conventional payload).

It's not easy to tell from just the pictures, but I think the large fairing should about be wide enough on it's widest to envelop the craft and simplify the aerodynamics. It'll need strutting, but that's not hard to do. In the pull frame design, place the fairing upside down from top to bottom.

If the CoM is not aligned well and offsetting that BZ-52/docking port on the bow is not an option, you can add a bit of strategically placed disposable mass on a decoupler to bring the CoM where it needs to be.

I don't expect it to be very problematic at all. Is the craft file available somewhere, for us to have a try at assembling a lifter?

It is indeed a radial attachment point. Though there are actually two equally spaced on the bow, they are hidden by the angled bow section usually but you can see them at that angle.

 

It has a Jr docking port centered on the front, I could switch it out for a regular sized one to use as a pull point. It is well above the center of mass, the weight is mostly in the engines and fuel tanks loaded in the stern. I believe a pull frame could work so far I've only been using the push frames. Unfortunately I have tried using a fairing but its just not large enough to envelope the bridge.

I could send you the craft file if you want to give it a shot, do you know any good file sharing sites? or I could just email it.

[Foxster]

Gotta say that HyperEdit would probably be my first choice for that "craft". 

[swjr-swis]

5 hours ago, ImperialistPigDog said:

Unfortunately I have tried using a fairing but its just not large enough to envelope the bridge.

Hmm ok, yes, I measured with a quick mockup of the bow, I see the bridge is actually higher. Could still use the fairing with a bit of clipping, but the parts that clip may not detach cleanly. Ok, no fairing, will just mean more drag, so more fuel to lob it up there, but could still be done.

 

5 hours ago, ImperialistPigDog said:

I could send you the craft file if you want to give it a shot, do you know any good file sharing sites? or I could just email it.

I can recommend KerbalX as a good craft sharing site. Dropbox is pretty ok for sporadic file sharing.

Edited April 10, 2016 by swjr-swis

[FyunchClick]

Can I recommend installing RCS Build Aid to help visualize your offset torque and COM, as well as provide numbers. You can then offset whatever you connect to that portal until it's right over COM, and attach your fairing from there, and if you keep your boosters symmetric you can often end up with as little as a few tenths of a nm of torque with a bit of precision offsetting. 

In addition, it also shows your dry center of mass so you can figure out if stability issues later in the launch aren't caused by your center of mass moving to far down (CoM shout stay above your center of drag or your rocket will want to fly backwards).

I've gotten big and radially very asymmetric payloads into orbit with relative ease that way.

[Pecan]

Answer 1: "How can I get this 142.8 ton ..." = with a 143tonne+ launch vehicle. (As others have said, the mass is the important thing for a launch vehicle, but the critical thing is to get the aerodynamics right).

Answer 2:  "How can I get this 142.8 ton ..." = looks like a right pig.  If you don't like Foxster's answer please let us have the .craft file and I'll see what I can do.

[ImperialistPigDog]

 

 

proto type is up! the launcher is very fidgety. I'm going to rebuild it, I believe the last stage is misaligned. 

[nater662]

For that use Hyper edit.