7+ Rovers, Part 2

Part 1 is here.

Excited by the relative success of the X1, I continued to experiment, until I came up with Artichoke Rover X2. It’s a boxy little robotic rover, using a “Probodobodyne QBE” command module and modular girders for it body. But with its fixed solar panels, single headlight, and six S2 wheels, it reminded me too much of the X1. I shelved the design, but may use it on a future mission.

I liked what I came up with for Artichoke Rover X3. It uses a 2×2 plate as its base, with a battery and remote guidance unit on top. It sits on four medium-sized “RoveMax Model M1” wheels. It has two headlights up front and a pair of movable solar panels on its sides. Even though it was designed as a robotic rover, I placed command seat between the headlights – just because it looked nice. X3 has plenty of ground clearance, and yet has a wide, low look to it.

A lander similar to the one which took X1 to Mun took X3 to Minmus – except that it had two engines instead of four, and it had landing legs. After dropping X3, the lander remained on Minmus.

X3 handled well on Minmus, even though the low gravity made traction a problem. It was like driving on ice-covered pavement. X3 would slide a little on acceleration, and slide even more on turns. It wasn’t too bad, however, and X3 had excellent stability. It seemed like it couldn’t tumble, no matter what.

Minmus is actually a rather boring place to explore. It’s covered in flat, featureless planes, and steep rounded mountains. From the viewpoint of a slow-moving rover, it looks pretty much the same no matter which direction you go.

Then I had the idea to give X3 someplace to go. I began building Minmus Base One. The complete story of Minmus Base One is the subject for another post. To keep things simple, the base was planned as a series of unconnected modules, and a single occupant: Burzer Kerman. I started the base at what I thought was a reasonable distance from X3 and its lander: 2.4 kilometers.

I discovered that, with a top speed of 1.2 meters per second, it took X3 a very long time to travel 2.4 kilometers to the base. But it made it.

If Burzer Kerman was to do any long-range exploration, he would need a faster rover – I figured extra weight should make it faster. I came up with Artichoke Rover X4 – long, with many girders, and eight tiny S2 wheels. But it seemed neither heavy enough nor fast enough for the task. So I built Artichoke Rover X5.

Artichoke Rover X5 is massive. Eight large TR-2L wheels attach, via long girders, to a 2-occupant MK-2 lander-can. In addition to electrical power supplied by batteries, solar panels, and thermoelectric generators, it had two ion-powered thrusters on its tail. It took an enormous rocket to send it, with a single astronaut aboard, to Minmus.

Something strange happened during the landing of X5, however. The lander got within a few hundred meters of the surface and then would begin spinning wildly – and crash. It didn’t seem to be a problem of imbalance – the spinning seemed too intense for that. Several attempts at landing were made, and several astronauts lost their lives.

I came up with the theory that, even though they were on a separate stage, those ion thrusters were firing during the landing – causing thrust to one side of the lander. I couldn’t think of any reason why that would be, but I could think of no other possible cause. I hadn’t yet learned the trick of right-clicking to disable engines, so I removed the ion thrusters and tried another launch.

Apparently, it was the ion thrusters causing the spin. Without them, Lodlong Kerman, aboard Artichoke Rover X5, landed safely on Minmus, 2.3 kilometers from Minmus Base One.

X5, which had handled so well on Kerbin, proved to be unmanageable on Minmus. The slightest of turns, at speeds as low as 0.1 meters per second, would cause X5 to begin to flip. After trying various combinations of disabling brakes and/or power to its eight wheels, all unsuccessfully, X5 was declared a lemon. Artichoke Rover X3 was sent from Minmus Base One to rescue Lodlong Kerman.

(With every rover, I attached MechJeb to the lander, but never to the rover.)

According to the forums, kerbals have weight, but only when they’re outside of a ship. X3 traveled at 1.2 meters per second from Minmus Base One, but with Lodlong aboard, it cruised at 4.9 m/s on the return trip. The added weight of a passenger made a difference.

Minumus base One now had two occupants, but only a single-seat rover for exploration.

I built Artichoke Rover X3.2 and sent it to Minmus Base One. X3.2 was identical to X3 in every way but the seating. One headlight was removed, moved to the center, and two seats were added – one on each side. While I was at it, I added three seats to the back.

With two kerbals aboard, X3.2 reached a speed of 7.1 meters per second. I also discovered something interesting about Kerbal Space Program: When two astronauts are facing opposite directions on a rover, the game will assume that the one seated last is in the front.

Horary Kerman became the third resident of Minmus Base One when he arrived in the ship that would bring all three residents home. Before shutting down the base, Burzer, Lodlong, and Horary took a ride to the nearest mountains aboard X3.2, reaching speeds in excess of 12 meters per second. They tried to climb the nearest hill, but the climb became too steep before they reached the peak. They went speeding over the low hills, becoming airborne (or whatever the term is when there is no “air”) many times, but never losing control.

Artichoke Rover X3.2 was the best rover I had designed, up to that point.

I was disappointed that X5 had been such a failure. Until it landed on Minmus, it had been my favorite design.

Part 3 is here.

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