A comparison of design, then and now

[Dave Kerbin]

I recently did a flight/challenge on reddit where I dug out the oldest craft I had and flew it. I decided to revist another old flight, this time from an engineering standpoint.

Back in September of last year I started a thread where I asked if my attempt at a low mass Mun flight seemed reasonable and if the math was correct. This was the first ship I designed by making delta-v calculations ahead of time (my excel method), instead of just trial and error.

My best design back then was this 34.5 ton ship. As part of the flight plan for this ship I tested and learned how to dock without RCS.

Anyway I'm taking a fresh look at designing a low mass mission. The basic criteria are no exploits (infinite glider, intake spamming, etc) and I'd like it to look good. While I'll admit to doing it over in my probe thread I'm not a fan of 'pancake' shaped ships on the launchpad.

Ultimately I came up with this. It weighs 21.99 tons on the launchpad (I used tweakables to drain a little unneeded fuel from the center booster) and looks reasonably like a rocket with a big center booster and 6 smaller boosters. The 2 fuel tanks on the side of the capsule are bending things a bit, they rely on the cubic strut trick to let me mount them radially like that. I did that mostly for looks, if you use a radial decoupler with the T100 tank it just looks terrible. Another alternative configuration that would have a slight effect on flight would be to place a single T200 tank on top, moving the parachutes to the sides. The weight can be brought back to 21.99t by removing the science gear which is just there for show (though you can actually get a lot of science using just those instruments plus kerbal stuff)

After launch there is still 6L of fuel left in the booster but for this mission I'm just going to discard it before burning for the Mun. The side tanks provide just enough fuel for injection and capture. I push away from them as I slightly adjust the orbit and prepare for landing.

So we land, plant a flag and come back. There is some fuel in the tank so I aerobrake and then setup a return to try and reach KSP. I managed to come down pretty close.

So with half a year of experience I've managed to knock of 1/3 of the weight and make it look nicer. But that's not really enough to show for improvement, especially when there are pancake ships that do it for under 15 tons. I don't really want to make a pancake so is there something else I can do, somewhere else I can go.

That is not how you get to Minmus. Arriving at Duna I have 3.06L of liquid fuel left in the side tanks. I'll use some of that to slightly adjust for aerocapture. I didn't actually get into orbit, instead coming into a long descent that brought me around to the day side of Duna (just barely). In the thin atmosphere I was still going over 400 m/s but the partially deployed chute slowly reduced until it fully deployed which instantly eliminated most of my horizontal velocity.

There is still 1.18L left in the side tanks so they'll last all of 2 seconds for the ascent. I got a little lazy on the return and didn't correct my return PE until I entered Kerbin's SOI. I burned most of the remaining 9L of fuel (close to 200 m/s) to correct and put myself into return over the pole.

[Scotius]

Congrats. Very efficient and capable small ship

[Wijbrandus]

I'm confused. If you used the parachute for the landing on Duna, how did you repack it to land on Kerbal?

[Vanamonde]

Wijbrandus, if you send a Kerbal out on EVA, there are several things he can do to parts, if he is close enough: repair broken tires, extend solar panels, and yes, repack parachutes for re-use. Triggering the chutes again can be tricky, though, because it messes up staging. Try using an action group instead.

[Dave Kerbin]

I'm confused. If you used the parachute for the landing on Duna, how did you repack it to land on Kerbal?

Kerbals can repack parachutes by right clicking them (they can also repair wheels and lander legs as long as they've been broken but not torn off or exploded). If your ladder is close enough to the parachute you can do it on the ground. If you have parachutes far away from any ladder then you can wait until you are back in space and do a space walk with the jetpack to reach them.

Edit:

Wijbrandus, if you send a Kerbal out on EVA, there are several things he can do to parts, if he is close enough: repair broken tires, extend solar panels, and yes, repack parachutes for re-use. Triggering the chutes again can be tricky, though, because it messes up staging. Try using an action group instead.

In this case I took some help from my probe career and set the parachutes deployment pressure for Kerbin (0.3 will open the chute at around 6000m by which time you should have slowed down enough). That way I could activate the chute (right click and select deploy) while I was in space on approach to Kerbin's atmosphere and it would automatically be released.