I'm doing a Duna landing and return with a spaceplane, any advice?

[Uberdude9001]

I'm going to start off by saying this is my first interplanetary mission that didn't involve landing a probe and leaving it on a planet. The method I am using might seem unnecessarily convoluted and complex but I am doing it because I feel more comfortable flying my SSTO spaceplane than I do flying a conventional lander.

My plan is to launch a spaceplane and an "interplanetary drive"(basically a nuclear engine and a big fuel tank with docking ports) up to a station in a 250km orbit of Kerbin. Once at the station the interplanetary drive and the spaceplane will both refuel. Once fueled up the spaceplane and drive will dock together and using the nuclear engine fly to Duna. Once they reach Duna I will use the interplanetary drive to get them both into a 60km orbit. The spaceplane will then reduce its periapsis to around 30km and let air friction take it down to the surface slowly for a landing.

My main concern is whether or not my spaceplane has enough delta V to return to a stable orbit. It can get into a 250km orbit of Kerbin with 2/3 of its fuel remaining;however, it can't use its jet engines on Duna because of the lack of air. Is 3000m/s Delta V enough to reach a stable orbit of Duna and what trajectory should I take to get to it efficiently?

Edited May 30, 2013 by Uberdude9001

[bsalis]

I think the delta-V is a bit under 1.5 km/s to low Duna orbit.

Are you going to land on the landing gear, or a tail landing (with legs)? If the former, how will you know if you have enough lift for a safe landing, then lift the nose off the ground for ascent again?

[Stelith61]

Wings on duna are basically completely useless for anything other than little ion gliders. A stable glide path is nearly 200m/s.

[Uberdude9001]

I attempted it in my spaceplane and the atmosphere was thinner than I expected, after repeated attempts my SSTO slammed into the ground and exploded. Despite this failure I will probably take a modified SSTO with landing legs to Duna in a few days. What landing legs would be optimal for an 18.3 ton craft?

[Caelib]

Wasn't able to determine this by reading your post, but have you landed on the Mun and returned? If not, I would start there.

As far as Duna ... use parachutes for your landing (use the big drag chute PLUS the normal ones) -- the atmosphere is thin, but the chutes should work just fine for you. As far as a spaceplane ... that is going to be very hard because the atmosphere is so thin -- you'll have to use rockets for 99.9% of the trip.

[Fox967]

No advice - just thought i'd come and wish you luck.

Good luck!

[Sabastian]

Wasn't able to determine this by reading your post, but have you landed on the Mun and returned? If not, I would start there.

As far as Duna ... use parachutes for your landing (use the big drag chute PLUS the normal ones) -- the atmosphere is thin, but the chutes should work just fine for you. As far as a spaceplane ... that is going to be very hard because the atmosphere is so thin -- you'll have to use rockets for 99.9% of the trip.

Good advice on the parachutes. I would also look into the drogue shoot and/or adding lots of struts to your design. I ran into issues on Duna with my lander coming apart at 500 ft AGL when the main chutes all deployed. Because the atmosphere is so much thinner, you're going much faster at 500 ft than you typically are on Kerbin. Thankfully I got all of the bugs ironed out of my lander before sending it down with a crew!

[Uberdude9001]

Wasn't able to determine this by reading your post, but have you landed on the Mun and returned? If not, I would start there.

As far as Duna ... use parachutes for your landing (use the big drag chute PLUS the normal ones) -- the atmosphere is thin, but the chutes should work just fine for you. As far as a spaceplane ... that is going to be very hard because the atmosphere is so thin -- you'll have to use rockets for 99.9% of the trip.

I have indeed landed on the mun both in a conventional lander and using my SSTO. In my previous attempt I could reach the ground and I retained enough control via RCS and thrust vectoring to reduce my velocity to as low as 50m/s and remain airborne. Sadly my landing gear require that I hit the ground at less than 5-10m/s. I am planning on fitting the plane with landing legs instead, but it is 18.3 tons and I don't know which legs to use.

[bsalis]

I always used the largest legs, and have landed 3 different types of SSTO Spaceplane on Duna.

You can see some pics here - http://forum.kerbalspaceprogram.com/showthread.php/29005-Boxkite-style-SSTO-Spaceplane

However they were all heavier than 18.3 tons. Perhaps try the smaller legs and test on Mun.

[Uberdude9001]

I always used the largest legs, and have landed 3 different types of SSTO Spaceplane on Duna.

You can see some pics here - http://forum.kerbalspaceprogram.com/showthread.php/29005-Boxkite-style-SSTO-Spaceplane

However they were all heavier than 18.3 tons. Perhaps try the smaller legs and test on Mun.

I've strengthened the hull of the SSTO significantly since my previous attempt without reducing its performance. It can now safely withstand landings with a downwards velocity of up to 25m/s without there being a high risk of important components falling off. I am going to attempt another Duna landing with this upgraded SSTO and if that fails I will attempt to use various types of legs. Thanks for the help everyone, I think this thread is finished.

[Jason Patterson]

You definitely can land a plane on Duna - it's just a matter of landing carefully in the right location. The large, dark maria near the equator are huge plains that make good landing strips. They are also at the datum altitude, so you'll get about as much lift as you can on Duna there. When I land on wheels on Duna I set my periapsis to ~5km so that I wind up coming down very gently. If you set yourself up for a more conventional landing with a carefully chosen site to touchdown upon, you're probably going to wind up having too much vertical velocity and will lithobrake.