A reusable two stage grand tour mission - Update: recovering Bill's craft from Eve

[EveMaster]

After designing my previous craft, the Eve Infinity (https://kerbalx.com/EveMaster/Eve-Infinity). I thought that this craft could be altered to make a grand tour possible.

The main changes were a full mining equipment also in the upper stage and two landing legs so that the upper stage could land vertically.

The result is the Reusable Grand Tour Vessel (https://kerbalx.com/EveMaster/Reusable-Grand-Tour-Vessel)

The mission is performed on a new sandgame game with normal difficulty.

The surfaces of the bodies are visited in the order: Minmus, Mun, Minmus, Ike, Duna, Dres, Laythe, Pol, Tylo, Val, Bop, Eeloo, Gilly, Moho, Eve, Gilly, Kerbin.

 

Mission Report:

The kerbals on the mission a the pilot Jebediah and the Engineer Bill. Firstly the whole craft flies as a single stage to the surface of Minmus. There the upper stage decouples and flies to the Mun surface. This landing one the moon is the only one where no mining is done because the upper stage still has enough fuel for the way back to Minmus. Then the whole craft flies to and lands on Ike. After that the upper stage lands on Duna and docks back to the lower stage in Duna orbit. On the next destination, Dres, only the upper stage lands.

The craft reaches the Jool system with an intercept tangentially to Laythe orbit an can easily aerocapture and land. The ascent from Laythe takes quite some fuel so the next stop is the low gravity moon Pol to get full on fuel again. For the Tylo landing the lower stage is left in an elliptical orbit. The Tylo landing succeeded on the first try. The fuel runs out as the craft is hovering closely above the surface and it lands without damage. Back in orbit the lower stage is about 20m/s short of reaching the other stage. The other stage only has reduced control because it has neither long range antenna nor a kerbal on board. So Jebediah goes on EVA to fly to the other stage and bring it back. Flying from elliptical Tylo orbit to low Val orbit it does not take that much delta-V so there is enough fuel left to be transferred to the upper stage. After the upper stage has visited Val the whole ship flies to the last of the Joolean, Bop.

The next stop is Eeloo. Only the upper stage lands there. Now Jebediah and Bill would like to go to Moho. But the delta-V requirements for going directly are way too high and the ship isn't even full on fuel. So Bill has the idea to stop at Gilly to refuel. But Jeb responds: "We don't have enough fuel to reach Gilly either." "Then let's use gravity assists." Bills responds. So they leave Eeloo and head for Duna. After leaving the SOI of Eeloo they notice that the Duna encounter won't get them anything useful. So they change their plan and make a course correction to make a Kerbin gravity assist. That works and brings them on a course to Eve. At Eve the speed is more than 5km/s and too high for an aerocapture. So the capture is mostly done by retroburning at an height of 81km above Eve. The apoapsis is now on the height of Gilly. After putting the periapsis out of the atmosphere and correcting the inclination to match the one of Gilly they notice that they don't have enough fuel left to reach Gilly. But Bill has an idea: "Lets transfer fuel to the upper stage, so that it can reach to Gilly and shuttle fuel back to the other stage." That works and after redocking the craft has enough fuel to reach Gilly as a whole an finally get refueled up completely.

The craft leaves Gilly at a point in time where Eve's and Moho's orbit intersect. The ejection burn contains a normal component to match the inclination of Moho's orbit. When the craft reaches its Kerbol periapsis which is at the height of Moho's orbit, Moho is not there. Performing some retroburning in deep space however gives an encounter with Moho one orbit later. When reaching orbit around Moho, Bill and Jebediah notice that they don't have enough fuel for landing the whole ship. So they do the same trick as for reaching Gilly. After two shuttle missions there is enough fuel for the whole ship to land. After refueling, the ship ascends to low Moho orbit. Bill notices: "Going to orbit has cost us quite some fuel. We could shuttle more fuel up by using the lower stage. I don't want to get stranded in deep space." Jeb: "You can do that if you want. I stay in the orbital stage while you do that." After around seven refueling runs the ship is as full on fuel as possible. Jeb got routine in doing so and by using the board computer he found it easy to rendezvous back and dock back with the orbital stage even without maneuver nodes. Jeb even risked putting less than 1000 m/s of delta-v into the tank some times when leaving for Moho surface.

Nearly full on fuel it is easy to transfer to Eve. There is even enough fuel for lowering the Eve apoapsis with a retroburn instead of mulitple aerobrake passes to save time. They make a final retroburn of more than 1000 m/s to descent to the highest mountain of Eve. They decided not to land directly on top but at the side of the mountain because there is a better landing area. After mining a bit of fuel they roll up to the very top of the mountain. Now it is time to say goodby for Bill and Jeb. Bill would stay on Eve to operate the lower stage that can push an upper stage into a suborbital trajectory. Jeb promises to come and visit Bill soon. Bill takes a seat in the lower stage and Jeb in the upper stage. They disable the fuel crossfeed so that the upper stage is full on fuel when decoupled. The craft takes of horizontally and quickly climbs to an angle of around 70 degrees then switches to prograde for a gravity turn. The throttle is at 100% all the time. When the fuel runs out in the bottom stage the vehicle travels at around 1700m/s and has an apoapsis at around 105km. Jeb pushes the upper stage into orbit while Bill returns the lower stage to the surface of Eve. The high wing area of the lower stage is needed to survive the reentry. The speed vertical component exceeds 1km/s at times and the resulting g-forces reach 9g. Nevertheless Bill manages to land it safely.

Jeb flies the upper stage from low Eve orbit to Gilly. When approaching Gilly Jeb becomes a bit worried. The current speed relative to Gilly equals the remaining delta-V left. Jeb decides to continue anyways but without capturing into an orbit first. He waits with the burn until he is very near the ground. After burning all his fuel, the speed is down to 1m/s and he is 3m above ground, safe for Gilly. After landing horizontally he puts the lander up vertically using the reaction wheels. This is only possible to the low gravity of Gilly. The vertical position has the advantage that the craft does not mystically wise sink into the ground when time warping during mining. Full on fuel again Jeb heads back to Kerbin. He descends at a steep angle because the craft does not glide as well on Kerbin as on Eve. With the landing on the runway of the KSC he has completed the 'Grand Tour' in less than 60 years.

Screenshots of the mission: https://imgur.com/gallery/phYIcHw

[EveMaster]

Part 2:

Back at the KSC plans to rescue Bill from the surface of Eve are made. Bill said he does not want to leave his craft behind on Eve. But it has not enough delta-V to reach orbit as a single stage. So the plan is to catch Bills craft that has a dry mass off 88 tons on a suborbital catcher and circularize before falling back to Eve. To bring this orbital catcher to low eve orbit, a spaceplane with a Mammoth stage for takeoff and an nuclear stage for transfers in the vacuum is designed.

The pilot Jeb and the engineer Rorima are flying the mission. The first stop on their route is Minmus. On Mimus the low TWR of the nuclear engines poses some challenge, but they manage to land safely. From there after refueling their next stop is Gilly.

On Gilly they refuel too and go into a 90km x 150km orbit around Eve with 25° inclination. The highest point of the orbit is at the southmost point. This is the optimal orbit for catching Bills craft. Jeb separates the orbital catcher and prepares to catch Bills craft. With careful timing Bill climbs into a suborbital trajectory with an apoapsis of 150km. Jeb decelerates and docks with Bills craft. Quickly they circularize back into orbit using a prograde burn with some radial component.

They then dock back together with the rest of the rescue craft and head to Gilly. On the intersect with Gilly they notice that they don't have enough fuel left for circularization so they discuss their options. Jeb has the idea to lithobreak on Gilly. "Too dangerous" says Bill, "I have another idea. If you undock my craft you have enough fuel to land on Gilly. You can pick me up later in an Eve orbit. They follow this plan and it indeed works.

After rendezvous around Eve they plan their way back to Kerbin. They decide to fly the two craft separately. As Bill is not a pilot, Jeb performs an EVA over to Bills craft and programs a maneuver node for Jeb into the board computer. The return to Kerbin is uneventful. Bill manages to land directly on the runway, but the rescue craft comes down before the mountain range near the KSC. So Jeb and Rorima mine some ore and generate some fuel to fly back to the runway.

Finaly all Kerbals are back at the KSC. A craft has landed on each body of the Kerbal system with a solid surface and every single part has been recovered.

 

The rescue craft circularizing around Eve:

Jeb sitting on the suborbital catcher stage:

Album with all screenshots of mission: https://imgur.com/gallery/xB10TAy

Album with all screenshots of the grand tour maneuvers: https://imgur.com/gallery/vpXbkb1

Edited September 28, 2019 by EveMaster