Flight Question Landing on Mars

[bloodtoes]

Hello,

I am interested in what sorts of Mars approaches/landings are possible? I usually use a method similar to landing on the moon but have trouble maintaining attitude in the atmosphere so I do the burn up between 80-120km alt resulting in an enormously long vertical descent, spending a lot of fuel on the hover engine.

[ame="http://vimeo.com/6059689"]'Earth to Mars' - An Orbiter Film on Vimeo[/ame]

In this video, Tex seems to use the atmosphere to reduce his speed. What do I need to know to at least practice coming in like that? For example, for unpowered landing on Earth I know that at an orbit of about 350km I can burn retro-grade on the other side of the planet to bring my PeA down to about 50km then come in with my nose up with an AoA of about 42.5 degrees and that's a good baseline to tweak from.

I usually fly the XR2.

 

[Andy44]

Mars is tough with winged vehicles, because the atmosphere is too thin to support your wing at low landing speeds, but thick enough to keep you from flying nose-high so you can use your hoverjets. With the DG I just do a lunar-style powered landing.

Most of my Mars flights have been with semi-realistic vehicles like the Ford Aeroneutronic Lander, which enters the atmosphere as a lifting body, but uses a parachute to slow down and go tail-first near the landing site, and finally uses rocket thrust for the final approach.

 

[flytandem]

I just fly the stock DG for simplicity and I've found it can actually dead stick and roll a landing to the hangars and fuel pads. I use RCS in ROT for the last couple of minutes of control as it allows better response and let's me get the nose higher than just with aero control. With most or all fuel gone it is light enough to slow to under 280 m/s groundspeed at point of contact with the ground. Still fast but it does make for a fun and meaningless challenge to occupy myself. The 80 KM long runway I placed at Olympus (base at mid field) helps but is still not excessively long for such a fast landing speed.

 

[Andy44]

280 m/s is about mach 0.8 at Earth sea level, I'd say that's a bit hard on the tires!

 

[flytandem]

280 m/s is about mach 0.8 at Earth sea level, I'd say that's a bit hard on the tires!

Ya. It's just an exercise in exploring the flight dynamics of a simulator to the extent the sim allows it. Sure the tires won't blow up, but the contact needs to be with slow vertical speed and wings level, and the steering very light to allow the landing to work. There's something fun and rewarding about not having added any fuel use to an entire EDL except for a tiny bit of RCS in the final seconds of the flight to control attitude, and then rolling to a stop on a fuel pad.

I've wondered if there is a way to have a ship change its shape from a low aspect ratio air plow for initial braking in an atmosphere to a very high aspect low wing loading glider (sailplane?) so that landings on Mars can be more like the current DG on Earth.