Duna and Eve gliders

[builder396]

Well all sort of have Eve and Duna as the first real planets we want to land on except for Kerbin.

There are plenty of ways to get it done, one of the predominant ways to set down would be parachutes. Even on Dunas thin atmosphere parachutes are the simplest and most reliable way to go, nevermind Eves legendary 5 atm at sea level. I dont think there are a lot of people who simply rely on complete rocket power to set down though, but I bet someone did it.

But has anybody though about strapping wings and ion thrusters to a probe core and landing with that instead?

It resulted in two different designs on my end, but they have similar capabilities, though the Eve design has a few advantages and can be adapted further. However, both designs are basically flying wing designs with twin ion thrusters and stuffed with all the science things except the lab, mystery goo and the junior.

Now the differences start.

Duna design front top and aft.

Eve design front and aft.

Duna design:

The Design uses a short fuselage with a tricycle landing gear pared with 2 very very long detachable wing sections that include the Ion thruster units and read landing gears. Mounted on the fuselage are 2 small rover wheels at the rear with the nose landing gear, the latter can be used for steering in this mode (rear steering proved even more unstable), and also most equipment such as solar panels, probe core etc.

The wings are slightly dihedral (angled upwards) so improve stability in flight and keep the wings away from the ground. Their large size enables reasonably low landing speeds even in an atmosphere as thin as Dunas, in flying configuration the glider weighs only 2.5 tons and can land at a speed of below 40 m/s (7 m/s on Kerbin). The Ion thrusters provide enough takeoff power to enable the craft to take off again and sustain itself in the air as long as the sun shines down on you. Vertical stabilisers are existent, but very minimalistic being just vertically placed elevons, that dont even move (setting them to the yaw axis caused the plane to drift opposite to the side you try to turn), but they do provide a limited stability that suffices unless you perform aerobatics.

The design can do its job reasonably well, its the second attempt, the first had crashed due to extremely high landing speeds thanks to its smaller wingspan. The Duna Glider can easily land on Dunas low level areas and is both easy and stable to fly. Take-off and low level flying can be done without large amounts of effort and stall behaviour is also quite satisfactory. However, the design is handicapped a lot by its landings. It tends to yaw to either side upon braking, which can only be countered by rolling the faster side of the glider back onto the ground and applying the brake again, but this requires a lot of precision, and this behaviour caused the gliders left wing to hit the ground and be partially destroyed. Even when used as a pure rover any thoughtless turn can mean that you tip over. However, the basic idea has proven itself as certain experiments can be performed a lot better, such as low atmosphere stuff, if you can take off several times, there is enough fuel to stay aloft for at least half an hour in total.

Eve design:

The second design built upon the experiences of the failed Duna Glider, but also adapted it to the different environment. The fuselage length was practically doubled, which enabled the same wing area as before while having only half the wing span. The wing design itself also changed slightly being a standard shoulder wing (looking a bit like a parasol wing from the top because they practically join in the middle) with the ion thrusters being below the wing. The vertical stabilisers are now definite vertical fins plus a control surface. The larger wings also enabled to use a lot more solar panels to be fitted, making extended use of full thrust possible during day (before it could only sustain 1/3 thrust). The landing gear is also redesigned to a normal tailwheel landing gear that is made out of both landing gear bays as well as radial air intakes acting as floats, making the glider fully amphibious. Rover wheels were completely omitted though, as well as the detachable wings. The weight increased to 3.61 tons, but that is acceptable as the wing area remained roughly the same and the atmosphere would be a lot thicker anyway

Flight behavior was considerably improved, stall behaviour was still very good for a flying wing aircraft. Landing speed was as low as 3.5 m/s, and sea level top speed measured slightly below 18 m/s. Take-off and flight are seamless, and landings are also unproblematic thanks to the shorter wingspan and redesigned landing gear. The Fuel load was also doubled giving it even more endurance and offsetting the lack of rover wheels as a xenon-free propulsion method.

So far the design has proven itself to be without major issues or malfunctions. Eve does rewrite a few books on avionics though, but even in those conditions the design performs flawlessly. The long endurance should enable me to explore larger parts of the planet in a shorter time than with a pure rover design, and dropping a rover with additional xenon to extend its service life even further would be of little difficulty. The same way additional science equipment could also be dropped, though the science lab would turn it into a manned mission negating a few of the advantages of unmanned missions, but the claw definitely makes this a possibility.

Generally, the glider idea does have a few good advantages for creating a long term presence on a planet. They only depend on xenon, but have a very large operational range and can get there very quickly in comparison to rovers. In addition, gliders can take off again and repeat experiments in the lower atmosphere, which is out of reach for a rover. The design can also be extended to have SSTO capability or personnel transport for return missions, the plane can glide to the surface with its full fuel load and take back off again once it has loaded everything it needs to load. Gliders also have the huge advantage of having a great liberty at their exact landing destination. While parachutes are almost entirely committed to one point of land, gliders can alter directions multiple times and choose any landing spot in a large area, making it possible to deliver cargo to a specified point, which is handy for setting up a compact base without having to drive the paradropped rover for half an hour towards the intended site because it went slightly off course.

Overall the glider idea has a lot of potential I'd say. Any other opinions?