Tips to improve this craft?

[John F. Kerman]

I'm trying to land on Jool's moons with this - the "best" design I've made so far (i.e. probably still terrible), but it's a real handful to fly. (I don't use mechjeb)

It's possible to get a decent orbit with practice, but the spin in the upper atmosphere is pretty annoying. Explosions aren't uncommon either.

I'm trying to improve the launch handling, and I'm not sure the nuclear / landing stage is all that efficient.

I think this only needs the DEMV addon, but I may have stuck some probodobodyne / remote tech / fixed camera / aviation light stuff on there as well. MkIV is the original version for reference.

Thanks for reading / trying it out

Edited October 9, 2012 by John F. Kerman

[ravenhawk82]

I'm on break at work and unable to try it out, but from looking at it, I can make a couple suggestions. First, I would suggest putting some standard SAS modules on all stages to assist in countering the rotation. Second, I would put a small RCS tank and some RCS thrusters on the lower portions of each stage to keep things stable on the way up and as parts begin to separate. Compliment these with some more RCS thrusters on your landing module to keep things nice and strait. This is almost standard on all of my larger rockets, just because they get topheavy and start to tip over as the huge lower fuel tanks run dry. I'm sure a more seasoned Kerbonaut can lend you some better tips, but these are just things I noticed right off the bat. Hope it helps a little!

[0jam3290]

May I suggest rcs to eliminate the spin?

EDIT: Dangit, I got ninjad'

Edited October 10, 2012 by 0jam3290

[antbin]

Can you post better screenshots? I'm not going to install DEMV.

From what I can see, you're using the non-gimbaling motors on the 2nd stage. That might be part of your spinning problem. You can add some canards/fins to the 2nd stage to help between 16-30,000m, but after that you'll need at least two thrust vectoring engines to control roll.

Edited October 10, 2012 by antbin

[sephirotic]

Despite what raven has already said: The bigger, the more unstable. Simple rule. You don´t need all that fuel and boosters to send that cart to laythe. The smaller spaceplane i got too laythe and back was less than 60 parts and, apart from the small drop fuel tanks on wings, single stage only.

[John F. Kerman]

Thanks for the replies so far, I will try these out. I thought one ASAS module on the upper stage was enough for the whole craft though?

From what I can see, you're using the non-gimbaling motors on the 2nd stage. That might be part of your spinning problem. You can add some canards/fins to the 2nd stage to help between 16-30,000m, but after that you'll need at least two thrust vectoring engines to control roll.

Yes, I'm using 4 non-gimbaling LFEs (plus the upper boosters) from about 10,000m until I'm nearly in orbit. I have a single gimbaling LFE in the centre which is fired a bit later on. I'm not entirely sure where to fit a second to be honest as the others are using symmetry.

The fuel tank between the DEMV & the lander used to be a structural fuselage but then I saw that LF tanks are a bit lighter when empty.

Despite what raven has already said: The bigger' date=' the more unstable. Simple rule. You don´t need all that fuel and boosters to send that cart to laythe. The smaller spaceplane i got too laythe and back was less than 60 parts and, apart from the small drop fuel tanks on wings, single stage only.

[/quote']

Yeah, I don't usually go for a design as large as this but I fancied a challenge, and I think it still has potential. Unfortunately, I'm rubbish at making spaceplanes.

Edited October 10, 2012 by John F. Kerman

[antbin]

I'm using 4 non-gimbaling LFEs (plus the upper boosters) from about 10,000m until I'm nearly in orbit. I have a single gimbaling LFE in the centre which is fired a bit later on.

What if you replaced the 4 non-gimbaling LFE's with two aerospikes and two gimbaling LFEs? You can just place the parts at 2x symmetry instead of 4x. Also an opportunity to use asparagus staging.

Without fins, you won't have much roll control without at least a pair of gimbaling engines.

Oh, and you are correct - one ASAS will serve your entire rocket.

[John F. Kerman]

Interesting.. would I need to rip stuff off and start again for that or would I be able to use 2x symmetry on the existing parts?

[antbin]

Well, you could remove the existing parts (grab them by the decoupler), then set the symmetry to 2x, then replace them. You can then Alt-click to duplicate the parts and place another pair at 2x symmetry.

Maybe you can relocate the boosters attached below? I would recommend replacing SRBs with drop fuel tanks and firing the liquid fuel engines as early as possible, as long as possible.