Reusable Atmo Lander

[Mephisto81]

Hi,

a bit of a late reply, but nevertheless:

I like using the combination of an interplantery mothership and a multipurpose lander. Only for the really hard cases I need specialized Landers this way. Eve in Stock or Titanus in the New Horizons mod for example.

The Landers should be able to

- reach Low Kerbin Orbit from the Space center center with chemical rockets

- land and ascent from Tylo

- fit in a Mk 3 Cargo Bay

- collect science.

A multipurpose lander for two Kerbals can be built with around 20t take-off weight

These requirements are the basis for the following design principles:

2 Kerbonauts and an advanced drone core, Service bays and Command Seats

In order to be able to collect multiple science samples from the same trip, either multiple non-reusable experiments have to be carried or a scientist is on board.
A pilot is necessary if no remote control is available. An advanced drone core can be used to store experiments or the Science Container. The drone core can also provide Kerbnet access and supply SAS in case of inexperienced Kerbals. Biggest hindrance is weight. Therefore, seats in servicebays are much lighter than a cockpit and protect in most cases against reentry heat.

Good engine performance in vacuum and in atmosphere: Aerospike

The engine must provide more than 1 TWR on Kerbin in the atmosphere at sea level. 1.2 to.1.4 is more practical. ISP in vacuum and in atmo must both be rather good. The aerospike is a natural choice, as it has an ISP of 290 in atmo and 340 in vacuum.

Drag-optimized design

As you are flying through atmosphere, you want to minimize your dV loss due to gravity and drag. This means: no open nodes anywhere, streamlined design, maybe control surfaces.

Maneuvering and docking

In order to detach from the main craft and redock again, a set of four RCS thrusters is suffcient translation. Rotation can be done with the reaction wheel. 

Descent modes: Powered descent, unpowered descent, parachute-assisted descent.
Because wings do not fit well in cargo bays, they are not used. Descent in atmosphere depends on the density and gravity of the world. The more fuel you can save during descent, the better your range on ascent. If the atmosphere is dense enough, parachutes can slow you down for a unpowered landing. If no atmosphere is present, you'll have to burn your way to the ground with a powered descent. Tylo is the hard case for this in stock.
If some atmosphere is present, parachutes can be deployed for slowing down. The final deceleration is with rocket engines. The descent profile is highly dependent on your target body. Generally speaking, if atmosphere is present, you want to make the most use of it with a very shallow approach from low orbit.

Stability and center of mass and lift
If your lander flips during ascend or descent, a closer look into center of mass and lift is advisable. Does the center of mass change with fuel consumption, so that the center of lift is suddenly above? Do you have control surfaces, to help with stability?


Here is an example of a lander concept:


https://kerbalx.com/Mephisto/X-82-Selene

[NSEP]

Have something like a spaceplane, it does not require ablator and does not need parachutes, you can just glide wherever you want to go. This works well with Eve and Laythe, but im certain that it might not work as well as Duna, Duna has a low atmospheric pressure so you might need to do a powered landing.

Here is an example:

This is the spaceplane used in the documentary Darwin IV Its simple and small.