Sending a Lander to Duna. How should I land it?

[yarknark]

Ok, so I like playing in the order of Orbiter > Lander > Rover > Kerbal for most planet missions in KSP. I've already got my orbiter, Explorer I, in a low polar Duna orbit. The next step is putting a lander there. I wanted to design something like the Phoenix lander. But I'm not entirely sure how to do this. I need to make sure I have enough fuel to land safely, but also not make it so the engine touches the ground and the landing skids don't. I could use external fuel tanks, but the lander's mostly packed with science, solar panels and batteries. One of my ideas was to land with the help of Puff Monoprop. engines, but I don't know if it'll be enough to land.
This is what the lander looks like (ofc everything will be retracted on launch)
So I'm not certain where I'd put fuel tanks or monoprop. tanks and whatnot to make it all land. One idea was a skycrane but I haven't ever tried to do that yet.

So, anyone who's better at this game than me, what might I be able to do to get this thing landed and if there's anything I should add, let me know please. Thanks

Edited May 14, 2022 by yarknark

[king of nowhere]

I never landed something that small on duna, only bigger stuff, and the way to go is to use parachutes to slow down. terminal velocity is around 30 m/s with a parachute, probably will be less for your small, light probe. In fact, a couple of radial parachutes may be enough to slow it down to the point that the landing legs can take the impact. If not, the smaller engine that can give it TWR 2 on duna (0.6 on kerbin) should be enough. Perhaps 3 ant engines attached radially and your smaller fuel tank on top.

[swjr-swis]

Perhaps something like this:

Radial drogue chutes, 6 of them. They'll be plenty for Duna for a craft like this.

3x Ant and one Doughnut for fuel. All at the bottom to keep CoM low... not that it matters much in this case.

The drogues lower drop rate to about 20 m/s. You can afford to wait until the last 100 m or so to use the Ants and bring that further down.

Arrived at our Red Buddy. Time to transmit some sweet science (and with a TWR of 1.11+, you can hop to nearby biomes and get some more).

Edited May 15, 2022 by swjr-swis
forgot craft link

[jimmymcgoochie]

Duna is a bit of a nuisance for landings- the atmosphere is too thick to ignore but too thin to use for a fully parachute landing, plus normal parachutes might not even open at all if you land in higher terrain due to the very low pressure.

Drogue chutes are a good bet to slow down most of the way to landing, with small rockets to cushion the impact. Drogue chutes will open earlier than mains and will both slow the probe down and make sure it points the right way up. Duna’s thin atmosphere actually helps out for rockets as they have only a very small performance loss compared to vacuum, plus with relatively benign 0.3G gravity you don’t need a whole lot of thrust to land- Ants or Spiders, or even linear RCS ports set to “fore by throttle” in their actuation toggles, would be enough if you had parachutes to do most of the work. Ants have the best ISP but Spiders have better gimbal control and are better suited for skycranes or attaching to the sides of the probe rather than the bottom.

You could attach your engines and tanks underneath; put the tanks and/or the engines on the sides; or even put the whole lot (plus chutes) on a detachable skycrane that can be jettisoned after landing, Curiosity/Perseverance-style. Fuel at the bottom might help slightly for weight distribution, but that doesn’t matter much when you have parachutes and reaction wheels to sort that out, while a skycrane would make the lander neater by getting rid of all the landing gubbins after they’ve done their job.

Oh, and make sure you position the solar panels so they won’t collide with the ground on landing, or clip into a skycrane that you’ll jettison before opening the panels out.

[yarknark]

Hey everyone, I'm happy to say I did it. I ended up using a Skycrane setup, and it worked. Landed near the poles, and got some good data from the southern basin.
It's successfully on Duna, and I hope to send a rover there next. Although the rocket is turning weirdly because of the rover body, I assume, but I think I can just use control from here on different parts to remedy it.
Again, thanks for the help, everyone!