Circumnavigating Stuff in the Kerbol System (with the KAN-KAN III)

[Nazalassa]

Well, it seems I'm never happy of my designs, and often want to change them to add and change things. Good thing I only went a sixth of Kerbin before now.

When travelling with the KAN-KAN II, I noticed quite a lot of problems with it.
First, it's absolutely not crash- and jump-resistant. Also not very speed-resistent.
Then, the wheels are not shielded from drag, thus hurting underwater performance quite a lot (speed divided by 6).
And then, it's quite heavy, with more than 6 tons.
And then... I'll stop there.

So, I started doing experiments again:

1. It looks like 2.5m service bays are big enough to shield rover wheels, but not 1.25m service bays.
          => I'll use that instead.

2. These service bays unfortunately have a low crash tolerance.
          => Put some armor on it.

3. The wheelbase has to be quite small.
          => There's nothing more reaction wheels can't handle.

4. Issues with steep slopes, especially brutal slope transitions.
          => @King of Nowhere's "Mantis claws" are an excellent solution. I guess there's no problem I use them.

5. The KAN-KAN II has a removable docking port (by EVA construction).
          => Add a dragless docking port attached to the engine plate.

6. Drag issues.
          => Make everything dragless.

I came up with the following rover (namely named the KAN-KAN III), which satisfies all the above points:

The armor is made of MH GPS-025 Grip Strips which have a crash tolerance of 80 m/s, much better than the service bay's 9m/s. The ones at the top are for falling upside-down, and there are four on the bottom as well, for falling upright. The protocol for dangerous situation is thus: quickly use the reaction wheels to get upside-down or, if that cannot be done, to get upright. There are four more for the sides but they are pretty much useless since they don't protect much.
It has been tested by dropping the rover from 50m, 100m on the runway. Guaranteed to work as advertised.

On the front you can see the "Mantis claws" which have a crash tolerance of 125 m/s. of course, they are dragless. Tested on the runway, 100% approved.

Inside the can are the two seats (at the front) and the batteries (at the back). There are two RTGs above the batteries. The two reaction wheels are hidden by the wheels.

Total part count is 38 in 1.944 tons.

---

Testing have been made and here are the results:

• Minmus: Excellent. The rover can reach speeds up to 60 m/s. Very maneuverable.
• Gilly: Excellent. Managed to reach 40 m/s before getting flung out on an escape trajectory at the top of a slope. Also very maneuverable.
• Tylo (other side of the spectrum): Excellent. Almost reached 100 m/s. Some parts exploded but they were just grip strips from the lower / frontal armor so nothing bad. "Mantis claws" survived. Handles jumps very well. Able to turn at 80 m/s at a decent angular speed.

Some notes on driving:

• At high speeds wheels absolutely don't want to turn. That has to be done through SAS and reaction wheels, and works very well.
• It is quite handy to set the SAS to Prograde () while the rover is roving. No SAS makes it very unstable. If it begins to shake too hard, deactivate SAS, then reactivate it.
  The main attitude issue with rovers is that the ground is not always with the same orientation. This means the usual SAS approach is not very useful.
  The two axes the SAS has to do with (from the rover's perspective, with a forwards-facing control point) are 1. roll (lateral inclination) which the SAS ignores, good for us; and 2. pitch (forwards inclination), which is a little trickier. But the rover's always going to go parallel to the ground. So setting the SAS to Prograde makes it follow the pitch of the ground. Problem solved.
• Prograde SAS still has to be switched off when turning with the reaction wheels, to avoid undesired shaking afterwards.
• Prograde SAS is very good at handling jumps. Either they are short enough the rover doesn't nosedive, and it survives (proof: 13m high on Tylo), or they are long enough there is time to change the rover's orientation to something more survivable.

Some modifications have also been made, like a wider and slightly longer wheelbase. The wheels stick out of the sides now.

Screenshots:

Spoiler

Minmus
 

Gilly
 

Tylo

 

Edited February 29 by Nazalassa
Tests

[damerell]

I remain a bit boggled by wheels inside the rover body, but there's no denying that little cylinder is quite adorable.

[Nazalassa]

Will add a drag flag. If set then there is some drag (ex. for not going too fast downwards underwater). If unset there won't be drag.

[Nazalassa]

Here is the drag flag! Well, it's more like a drag wheel, but whatever.

As per @Lt_Duckweed's advice, I have added a small cargo bay at the bottom of the craft, and put a wheel in it - the small, steerable, no-brakes one. Why? It has a crash tolerance of 325 m/s, and previous tests, made with less crash-resistant parts, always ended with said part 'splashing down hard and [being] destroyed'. I'm pretty confident that the wheel is resistant enough.

Also, it added more weight to the rover, even with the removal of the front and lower armor (there are already "Mantis claws" on the front, and to lower armor kept exploding when it would've been useful, and isn't really needed). Weight now: 2.012 tons. I have to shave some mass if I want to keep it within 2 tons.

Edit - Getting rid of one unneeded battery brought the mass back to 1.992 tons. Good.

 

Here seen in action:

Safely touched down

Edited March 9 by Nazalassa