Grand Tour Tips

[Jacob Kerman]

I'm going to make my first Grand Tour craft. Does anybody have any good tips or suggestions for it?

 

[fulgur]

It really depends on what your design requirements are. You can do it in anything from a 10,000 tonne monster to a 11.5 tonne spaceplane if you are clever enough.

Personally, I would recommend a fairly large interplanetary mothership - one which can insert itself into orbit around Moho or Eeloo directly from Kerbin with payload attached. I would also recommend that you have an ISRU lander so you can refuel at Moho or Eeloo, as well as separate ships for Eve, Tylo and Laythe (these can be combined if you are able). Of course, I didn't do any of that (see my signature).

[RevanX_LSR]

Use a medium sized (100 ton) spaceplane to bring a large tank of nuclear and conventional fuel into space, and assemble a separate lander for Eve and Tylo.  You can use the spaceplane to land on Laythe if you want. Make a basic lander for all other bodies that can make it in a single stage and send it off to interplanetary space with a nuclear rocket. make it re dock to the mothership (nuclear rocket) and return to the mega tank and repeat for all the bodies. You may end up using more than 100 tons. If you are afraid of fuel shortages, prepare an ISRU module for refueling.

 

Most of the other bodies are very easy to land and return, so you only need a simple design. to save fuel, use two 400 tanks and a nerv motor offsetted 2/3 the way into the tanks. This gives you space for landing legs. Use an mk1 command pod with parachutes (not necessarily, this only helps for duna). Ensure your TwR on kerbin exceeds 0.35 so you can take off easily on duna (which has the highest gravity), and you can even strap on a cr7 rapier engine and another small tank for laythe.

 

Laythe is the easiest of the three “large” bodies to land and ascent. Since laythe atmosphere thickens so rapidly, simply descent the following craft from low orbit just before hitting the landmass:

1x CR7 rapier engine with 400 fuel and four radial ramp intakes (the small kind), 2 wings attached in mirror symmetry to the craft, as well as landing legs

decoupler

1x NERV motor with 400 fuel or 800 if you used the previous design

parachutes. enough to slow you down.

once you land, hope you land on flat ground and ascent back up vertically until 5km, then turn sideways and accelerate until 500m/s, before climbing rapidly to 20km. At that point due to laythe’s scale height the atmosphere is still thick but not enough to impede your crafts acceleration. Slowly climb even more until you jets fail. Then decouple and use the nerv to circularise.

 

Tylo: Use two stages of rocket propulsion, like an 800+dart and 400+terrier to land and ascent. Land on high points to save delta-v (not worth it however) and maintain a constant altitude of 3 kilometres over the terrain to avoid crashing.

 

Eve:

Use 1x vector engine with 6400 rockomax tank and then the tylo lander-like on top.  Also put an ion stage, since you should go there separately and land before returning back to main craft, due to this crafts large size.

Land on a high peak like the crater rim mountains to save delta v. they are usually at a latitude so circularise in an inclined orbit and wait for it to fall overhead. This takes trial, error and quick saving.

Ascend vertically up until 20 kilometres, then slowly do a kerbin like gravity turn. You should have more than enough delta-v to circularise with the third stage, so use that stage to extend out your orbit and do the first part of kerbin transfer.

Edited July 16, 2023 by JNSQFan

[jimmymcgoochie]

You can land everywhere except Tylo, Laythe and Eve using a single, simple design: Mk1 lander can, FL-T400, Swivel with docking gubbins and power generation as needed. For Tylo that lander can serve as the ascent stage with a suitable descent stage, either a Poodle or Making History Cheetah will do, for Laythe an air-breathing SSTO spaceplane is an attractive option and for Eve you’ll need either some physics-exploiting plane shenanigans or just a lot of fuel and Vectors combined with a lot of patience and use of the F9 key.

Moving that stuff around isn’t too difficult if you can refuel using ISRU on the smaller bodies- Minmus, Gilly, Pol, Bop and Ike are all relatively easy to land on for this purpose. I’d suggest keeping the ISRUs on the main mothership rather than doing some kind of detachable refuelling rig as that would just add complexity. Your Eve lander will (probably) be one of the heaviest parts of the mission so best to get that done first, while Tylo and Laythe require the most specialised hardware due to the higher delta-V requirements and Laythe’s atmosphere so should also be high on the list.