Sleepy_Steve

Why in god's name do you need to take 107 tons on a Duna mission?

Yeah, the mono prop is there from docking requirements on the Jool mission I'm doing... It's basically a flotilla of 7 different vessels sent on a large single ship. The idea is that when the mission's landings are finished, that I'll consolidate all remaining fuel and RCS into the return ship and see how far it can make it home. Would it make more sense to burn off the extra RCS first and ditch those tanks before using the last of my fuel? Even though I'd be pushing a much larger mass with the RCS?

The full parts list is: Mk1-2 Pod, 2 radial parachutes, 1 smallest solar panel, 4 FL-R25 RCS Tank, and 3 docking ports. Engines are the 0-10's. So I'm seeing a full mass of 6.77 and a dry mass of 5.15 at an ISP of 290.... 777.3 m/s. This is basically my emergency stage. I won't know how much of it I need to use till I'm done with the visit all the moons portion of the jool mission. But I do fully expect to run out of traditional fuel before I make it back to Kerbin. How much of the ship I use to come back might be pretty minimal since there are a bunch of options with the way I designed the ship's different modules. My plan is to use whatever is the minimum possible to fit the remaining fuel into, but even that I expect to run out.

Lets say I have a ship with a 3 man capsule, it's got its own supply of RCS, and then 4 of those medium RCS tanks on it with 100 RCS each. And now lets put on two or three of those RCS engines.... How far could it go? Hypothetically, if this ship were to run out of fuel coming back from say... Jool; how screwed are the occupants?

Mission Update: ^ Ejection burn was not as smooth as I'd hoped. ~300m/s for plane change. Then I needed about 1500 m/s of burning negative radial to get an encounter with a 500km periaps at Jool. More burns are needed later to tweak into aerobreaking. So... burning radial on ejection + massive radial correction = I goofed the pre-burns and possibly missed the ideal point in my transfer window... I've noticed Alarm Clock and MechJeb have different estimations of transfer windows. MechJeb normally coming before alarm clock. Cross feed in the docking ports caused me to drain all my landers without realizing it. Now my center core is down to about a third of a jumbo-64 tank. I'm not sure how much deltaV the thing has left any more. I will not scrap any mission objectives.

Well, I think I made it... at least the main burn was done. I increased my apoapsis in the wrong angle, and had to do some odd radial stuff to get the ejection angle right. Hopefully a plane change at the AN and an encounter tweak can get me an encounter. This is a lot harder than my probes or the ship I sent to duna. Maybe it's the low TWR?

ok, so to update this... how do I estimate my burn time needed for my 1900m/s transfer burn? 190 tons, 240 thrust from the four nukes... My rough guesstimate is somewhere between a 20 and 30 minute burn. If I raise the apoapsis of the orbit to near the mun that reduces the required burn length by 42%... but that still means a 10-15 minute burn, and that still seems overly long. How accurate are my estimates? And what else can I do to make it work better? Raise my periapsis higher to give more time to do the burn? Give the ship a brief kick on the final transfer burn to Jool by turning on the Skipper and two Rockomax 48-7s for a little bit?

Related question... if using mechjeb, do existing modules on craft already in flight get feature updates when they are unlocked in the science tree, or do you have to launch fresh mech-jeb parts to gain that functionality (for example, docking autopilot)

Farmed out some contracts for science and cash. Saw some contracts expiring. I'm doing fairly routine round trips to Minmus and Mun on a single launch for $44k, and taking home normally a bit over $150k in revenue by the end of the mission.

Tylo is first, it's lander is by far the most massive... This is the untested design I came up with below. I didn't have the large docking ports yet for the big interplanetary stage (not outlined in a square) to be 100% reusable, and I don't have the large RCS tanks so I expect a pretty ugly addition to the nose of the large capsule before too long. Single launch because I'm lazy. 239 parts and 109 tons so far... Now I just have to get Bill and Jeb back from other missions, slap on a bit more RCS, and add.... 7300 liquid fuel and however much oxidizer that needs.

Now just to figure out total payload mass in the landers...

That's a good point about the non low circular orbit for the main craft. And if I split off landers relatively early, I don't have to move the WHOLE monstrosity around to each moon. That's also a very pretty delta-V map. The plan is to base the mothership around the ship on the left of this image: Initial changes are less RCS, and no science module to save payload. Additionally, two of the LV-N nacelles will be detachable tugs with probe bodies and RCS to help the landers get where they need to be without moving the whole thing around. Tylo lander would dock to the back of that ship, and the configuration would allow me to drop any number of the landers once I'm done with them and up to two of the four nukes. The two other landers would attach to docking ports at the end of the detachable nacells.

So I'm planning a joolean grand tour. Woo!! I'm going to be using 3 different partially reusable landers, and a central interplanetary tug for the mission. The goal is to hit all 5 moons. But when I look at the deltaV map I get something like 14km/sec deltaV needed on the tug to go there, visit all the moons, and come back. That strikes me as a bit excessive, is that even in the right ball park?

Finally got around to my first successful Duna landing, and topped it off with a visit to Ike first. Had about 4k dV after landing for the return journey to Kerbin. Jeb's now sitting in orbit waiting for the return transfer window. With any luck he'll be back in time for the first manned Joolean mission.

Mission update, added drogue chutes to the design and a couple of struts to the outer tanks of the lander. Made it to the Duna system, landed on Ike, scienced, then landed on Duna. After landing on Duna, doing more science, and re-adjusting staging for landing I had ~4km dV to get me home in the lander. Was able to get about 1100 science from completing contracts and transmitting eva/crew reports before heading home. It's currently in orbit around duna waiting on the transfer window home.