Hercules II Superlifter

[Analogy]

I went back to the drawing board a bit, I heavily revised the staging so that booster drops are about the same amount of time apart, the first stage is longer so you have 9 engines burning for more of the crucial stage while the vehicle is still in the atmosphere, and I redesigned the way things are attached so that it\'s easy to put your own payload on it.

This vehicle can put about 50 mass units (equivalent to 20 tanks of fuel) into a 200km orbit using 26 tanks of fuel, or a lighter load into a higher orbit or injection/escape trajectory... In practice your load is probably going to be a fully-functional spacecraft that can just boost itself the rest of the way. =D A payload around 50 mass is going to be the limit in practice because 9 T-30 engines can\'t lift more than about 135 mass, so if you go over that the vehicle will just sit on the pad burning fuel until it gets light enough to take off... At which point you won\'t have enough fuel to achieve orbit anymore. It\'s a bit of a strange limiting condition, for sure.

I tested it by hacking a part to have 40 mass and putting that in the 'payload positon.' You can see that in the first and second screenshots. I also built an amalgamation of fuel tanks that could fit around the boosters as a more 'real world' scenario, that\'s the third screenshot.

My intention here is to make a spacecraft that other people will put their own payload on. To do this, disconnect the fuel tank on the middlemost engine from the command module, build your payload onto the command module, then move the booster onto the payload. I made sure to put the shortest stacks on the left and right so that you can build a payload with wings that stick through those slots if you want.

My first attempt at this concept of making the boosters different lengths put the lengths of the boosters down below so that a payload up top could be any shape at all rather than having to fit around the boosters... This didn\'t work because with a very heavy payload on top (i.e. the kind of payload I was designing this rocket for), the center of gravity moved too far away from the engines and the vehicle became unstable. As it is I had to reinforce the hell out of it

I\'m reasonably sure that this is just about the most mass to orbit that is possible with 9 engines. Feel free to prove me wrong.

I believe that this general paradigm of ship design is the strongest in the game... Every engine that\'s not firing because it\'s tied up in a stage is dead weight that\'s eating up your delta-v, so arranging things so that every engine on your vehicle is contributing to putting it into space is really nice. The fact that you have lots of engines on individual couplers gives you lots of opportunities to fine tune your staging so that you can find the best tradeoff between ditching dead weight and losing thrust.

The downside is that setting up the crossfeeds and staging is really tedious, and center of gravity and instability issues crop up constantly.

[noneyabidnis]

I love the concept, but can\'t get it balanced to save my life. And can\'t figure out the staging.

[Analogy]

Drop a stage every time a pair of engines stops firing, or look for the number of empty fuel tanks over on the left - 10 tanks for first stage, 8 for second, 6 for third, 2 for fourth.

If you have a tall payload you will want to throw some bracing struts on it. The rocket is very stable for a short payload (like my 'dummy weight' I tested it with), but a higher center of gravity will need bracing. Remember you\'re throwing a *lot* of mass on top of this thing, and rockets don\'t like having a high center of gravity that wobbles around. You might also need to throw some SAS and/or fins. These additions will come out of your payload to orbit, unfortunately.

Fly it up without a payload and you\'ll see it\'s pretty stable. It\'s putting 45 mass of payload on it that makes things difficult.

[noneyabidnis]

yeah, I think the issue is that my payload was too tall. However, I\'m not sure how to add more than 20 tons (ballpark) without it getting tall. If that makes sense. Of course, I like to have an initial stage that gets me near orbit, then another stage that finishes orbit and transfer, and then a final stage to get me back down (and even back from Mun, etc.) Thus I treat the craft as a wedding cake design - with this, though, I guess I don\'t need a wedding cake rocket and need to change my thinking.

[noneyabidnis]

wow - I just tried with a shorter payload and it went amazingly well. This is beautiful.

[jolee1868]

Interesting im going to have to play around with this setup