Flieger, grüß' mir die Sonne, grüß' mir die Sterne und grüß' mir den Mond. Dein Leben, das ist ein Schweben, durch die Ferne, die keiner bewohnt! - Hans Albers, F.P.1 antwortet nicht (Adaptation in the 80s: Extrabreit)

Tuesday, 2 June 2015

How to plan interplanetary travels

By hindsight, I realize more and more that those flights with the Fuel Jumbo could have been much easier by doing three things: adjust the control surfaces so that they do not oversteer and thereby fix annoying SAS behaviour, add some struts, add RCS engines and use RCS instead of weak torque wheels (the bigger ones are still locked in a tech node). Looking at my screenshots, I also realize that this plane does not look so bad at all. And it did its job. Maybe I did a bit injustice to this plane type, so this should be remedied.

- henceforth to bear the honored name "Fuel Dragon"

So, Duna was on top of my to-do list, right? Having researched a bit more whether and what more there is to interplanetary travels, the following two link are really helpful:
- Best way to plan interplanetary travel!
- Best tool + links to plan interplanetary travel

Playing around with the calculator from the latter link, the shortest travel time to Duna could even be as short as 151 days, but a single trip would then cost 4463dV, which the Omniscient cannot muster. Then I realize surprised that the current launch window is not optimal at all (year 1 day 151) and it is going to be much better in year 1 day 272! Concerning the return trip, I also realize surprised that, apparently, it is not possible to use the same transfer window for a return trip. So, interplanetary transfer windows do not seem to be like "windows" or "tunnels" through which you can pass back and forth; they are one-way streets. According to the calculator, in order to get back from Duna, the Omniscient would have to wait about 1.5 years for the next suitable transfer window! Looking for other stuff to do instead, i.e. flyby´s to other planets is not an option: too much additional dV required. I guess this is where the new ore/fuel refinery equipment is going to come in. Which means, I will need much more tech, in order to be able to equip my spacecrafts with refuel capacity for a true roundtrip of the Kerbol system.

Taking some notes from the calculator:
Prograde-Outward trips:
Duna: y1d187-d295 eta 272d
Dres: y1d360-d410 eta 268d
Jool: y2 d216 eta 199d

Retrograde-Inward trips:
Eve: y2d153 eta 197d
Moho: y1d263 eta 136d

Uh, why am I doing this work? I sure do not need to reinvent the wheel, there must be players out there who did exactly what I am doing here. Look internet? Yes, look internet! Presto, a spreadsheet which lists all transfer windows, together with the required deltaV; only the travel durations are missing. Do I love the Internet? Yes, I do love the Internet!

Surprisingly, a transfer window to Jool is close at y1 d166, needing only 2000 deltaV, and again one at y1 d282. And Duna is not so close as I had thought; the last transfer window was at y1 d58 and one will be open again in only in y1 d290, for 1700 deltaV. Of course, I could also travel outside those transfer windows; the travel time might even be not much longer, however, the deltaV requirements would easily skyrocket. There is only so much you can achieve with primitive combustion enginges, I guess.

So, the result of my little internet research is, there is currently no really good transfer window to Duna, so I am actually not under time pressure to launch that Duna mission. Good that I actually looked it up. This means I can rearrange my plans. Four more contracts did pop up in the meanwhile and I collect them all, they are well doable within the Kerbin SOI. Also, I now have a stash of four tourist contracts. They want to go a bit of everywhere, Mun, Minmus and Solar orbit and flyby (which should be synonymous). Combine this with this idea of doing an educational flight for all of my remaining Kerbonauts in oder to boost their skill level, and a new idea about another opportunity for a very efficient mission profile comes into my mind.

10 Kerbonauts easily fit into the Omniscient. The overall 10 tourists can be crammed in there, on top, too. So, the Omniscient´s virgin flight will actually not as a long-year home for four Kerbonauts, but as a tightly crammed passenger flight for 20 passengers. Since the roundtrip to Mun, then Minmus, then into the sun´s SOI probably takes about two weeks at best, there should also role-playing wise not be a problem having a this full spacecraft.

Concerning this role-playing thing: In a later new career run I might want to install two more mods; life-support and colonizing. This would make the game much more realistic and thus more coherent for me. I would have to plan and construct spaceships which have large living spaces and probably also agronomical installations which produce oxygen and food for multiple-year expeditions. Indeed, spacecrafts would not a spacecraft in the classic sense, but resemble more to travelling space stations. And I then could also settle out there, wohooo, this would give this game an entire new dimension. Sim-City in space, with real physics and logistics behind it! I realize there is also a mod which makes radio transmissions more realistic; however, this would just add more tediousness to the game and I prefer to assume that my Kerbals can coordinate at least the timing of radio transmissions and launch relay satelites by themselves.

In order to bring all passengers aboard, the White Goose spaceplane needs an additional passenger module. Like this, all passengers are going to be up there with merely two flights. As a positive side effect, the center of mass is now much better situated. Just the launch now needs to use the runway more like a ramp, but, hey, a launch is a launch!

- one White Goose passenger flight coming up; note the "fog" which are clouds from my latest installed mod ("EVE")

On my first trip up, I also use the occasion to rescue another Kerbonaut. After he is on board, I realise that the White Goose does note have solar panels and thus cannot make it in time to the Omniscient. The White Goose was designed for very short trips to a single destination and not for multiple extended rendez vous missions. Then I also screw up the re-entry by coming down way too early, thus needing a long flight to the Space Center. No, thanks, reload.

For my second try, I upgrade the spaceplane with solar panels from my recently unlocked tech node, stabilize the wings with more struts and adapt the control surfaces. Much much better, so I finally go up and dock to the Omniscient. Which makes me realize once more the bad response from torque, so I better also add more RCS and monopropellant for the next time. My spaceplanes are finally getting the required fine-tuning.

- a return trip with a rescued Kerbonaut on board

In the meanwhile, real life time warped from late night into morning time, the hallmark of really good computer games. Logoff.

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