Apollo style to Duna.

[Scarecrow88]

I recently did a complete redesign of my Apollo style Mun rocket, to take advantage of the Alcor landing capsule, which is way better looking than the stock 2-man lander can, and to try and improve the efficiency. The resulting ship was so good that I thought a few tweaks would allow me to get it to Duna and back, with no changes needed at all to the Excursion module apart from the addition of a drogue chute and normal chute.

The tweaks I made included a Duna insertion stage, added between the lifting stage and the Command module/Lander assembly, and some boosters added to the lifting stage.

The Mission

Lift off to orbit went smoothly. The second set of boosters were jettisoned just after completing the gravity turn, together with the escape tower. The 1st stage was jettisoned once out of fuel, and the second stage used to complete a parking orbit at around 85km.

A manoeuvre node was set up for the insertion burn, and the remaining fuel in the second stage was used at the start of the burn, before the second stage was finally jettisoned and the rest of the burn was completed with the Duna insertion stage. A small correction burn was made mid-insertion to make good the Duna encounter, and once the ship entered the Duna SOI, another short burn was made to bring the Pe down to take advantage of aerobraking to save more fuel. A few short burns were made to complete the capture at Duna and to establish an orbit at 45km.

With a good orbit established, the covers around the lander were shed, the CSM disengaged to turn around and extract the lander from the insertion stage, which was finally cast off despite still having a fair amount of fuel in the tanks.

After a couple of orbits to check out possible landing sites, Jebediah and Bill made the transfer to the lander module and, after making their final checks, disengaged from the CSM to start their journey to the planet surface. A short burn was enough to break orbit and set their resulting Pe to around 9km. Approaching Pe, the drogue chute was activated, and once it fully deployed, the main chute was also activated with deployment set to 500m agl. At 200m agl, and with the descent speed under the chutes at around 36m/s, it only took a few short bursts on the descent module engine to bring this down to a more acceptable level prior to touchdown.

At this point Jeb and Bill patted themselves on the back for a job well done, and descended to the surface to stretch their legs.

After a reasonable time on the surface, Jeb and Bill returned to the lander capsule to start making their preparations for a return to orbit, and a rendezvous with the CSM. At the appropriate time, with the CSM approaching above them from the west, Jeb fired up the descent module engine to commence what would initially be a vertical climb. With the atmosphere on Duna not extending as high as that on Kerbin, and being less dense, Jeb started a gravity turn at around 6000m, and with the climb fully established, jettisoned the descent stage when it ran out of fuel and simultaneously fired the ascent module engine for the final stage of their rendezvous manoeuvres. Rendezvous and docking all went according to plan, and the two vehicles were finally united with plenty of fuel in reserve in the ascent module.

Jeb and Bill shut everything down before transferring back to the CSM, where they were happy to tell Bob all about their excursion. They knew it would be a while before a transfer window to return to Kerbin would be available, so they left the ascent module attached, just for the extra room it provided. When the transfer window was finally upon them, they at last jettisoned the ascent module and made their preparations for the journey home. Their initial burn was a good one, setting up a good encounter with Kerbin, and they only required a correction burn once in Kerbin's SOI, again to make use of aerobraking in Kerbin's atmosphere, though they actually had enough fuel on board at this point that they could have achieved capture without aerobraking.

The final part of their journey involved a relatively simple orbit breaking burn to bring them back to Kerbin's surface, though Jeb was a little bit annoyed that he missed the runway at KSC, and had to console himself with the fact that at least they were close enough to make it back in time for tea.

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Edited October 25, 2014 by Scarecrow88

[Fox62]

Clever. *10 char damnation shall be inserted here*

[meve12]

Had you considered using the insertion stage as a crasher stage, to "boost" the LM into a descent trajectory?

[Scarecrow88]

I could have done that, by separating the Command Module and using the insertion stage to de-orbit the LM, but I wanted to mimic an Apollo style mission, which required the CM to detach, turn around, and 'extract' the LM from the insertion stage. Frankly I was surprised at how much surplus fuel this vehicle was carrying to achieve a Duna mission, and I'm starting to think I can probably use it for a mission to one of the Jool moons, probably Laythe or one with low gravity, without making any changes to it.