So far all my Fidos have been unmanned probes, but I thought it would be fun to try out a Fido that carried kerbals. This meant rebuilding another Fido from scratch because I wanted a two-kerbal lander cabin as the main control pod, but there is no way to 'demote' the existing probe body to not be the main pod (this is important because if the two-kerbal cabin is not the main pod on launch, the ship is not assigned any kerbals). So, as I said, this entailed a rebuild with the two-kerbal cabin as the main pod, but I also used an octagonal probe body at the center of the structure as before, and I made sure to flip this probe body upside-down relative to the main cabin during assembly so that I could use it to control the rocket during launch when the Fido is upside-down and therefore the cabin would be giving reversed direction readings. Below is the Fido K (for Fido with Kerbals) on its rocket.
The astronauts for this mission were Gergan Kerman and Cammon Kerman, undoubtedly chosen for their skills at joyriding. The Fido K is shown below in orbit around Kerbin before departure for Minmus. Because the two-kerbal cabin comes in the large Rockomax diameter, a large central tank was used, and two LV-T45 engines mounted on side-pod tanks. The transfer stage for the initial boost to Minmus uses a Rockomax Poodle engine.
The Fido K with its two friends aboard was sent to the growing Fido Base on Minmus. My landing was rather sloppy this time, and it took a lot of hovering around to get the lander moved into position for landing by the other vehicles... but I had plenty of fuel, so this was not a problem. Below we see the Fido K coming in under its Carrier.
I brought the Carrier in for a full landing (rather than any sky crane maneuver) so that I could transfer RCS fuel from its tanks to those of the Fido K after landing. I should really turn off the fuel flow from the Fido's tanks during the flight from Kerbin and landing on Minmus to keep them from being used, but this method worked fine too.
After topping off the Fido's RCS tanks, I did a little jump maneuver to separate the Carrier. A short burst from the Carrier's engines lifted the Carrier and Fido up, and then I cutoff the thrust and separated the Fido, moving it away from under the Carrier with a burst of the Fido's RCS jets. This was a bit hairier than usual because the Fido K is much more top heavy than other Fidos, so it was more tipsy...but it settled in safely. And I was surprised that the Carrier landed upright on its engine nozzles (since it is uncontrolled at this point...there is no probe body on this Carrier).
Below, the Fido K (in the foreground) has had its rear side-firing RCS nozzles manually deactivated so that it is ready to run with steering enabled. The bottom structure of the Fido K is essentially the same as that of the Fido Pup (the smaller Fido in the background).
The Fido K has four lights mounted on the sides of the cabin for good illumination.
Note that the two-kerbal lander cabin has large windows that extend out from the side to give the pilot a good view of the surface. Here's the previous nighttime view as seen through the pilot windows.
And below is the pilot view out the windows the next day before an expedition up Near Cheek to test out the Fido K's handling.
Because of the crew cabin, the Fido K is much more top heavy than my other Fidos. As a result, it is not safe to drive it at high speeds...I'd keep it below 20 m/s. And you must be especially careful about not making sudden turns or even using the brakes at speed, or the Fido K can wipe out. This means that slowing down the Fido K takes longer than other Fidos since the brakes can only be applied in short bursts...or it means using RCS fuel to slow the Fido K down (the RCS thrusters are higher up than the wheels, so they don't have the same tendency to flip the Fido. Oddly, probably also because of the different center of gravity, I can flip a toppled Fido K back upright much more easily using coordinated thruster bursts that I can with other Fidos (this assumes that you toppled the Fido K at a slow speed and it is undamaged... wiping out at high speeds can destroy the Fido K). Below, the Fido K is seen going up the slope of Near Cheek.
The crew cabin has a rear hatch, and I installed a ladder so that the crew can do EVAs to investigate anything interesting they find. Below we see Gergan having fun on top of the Fido K (to a kerbal with a rocket pack, anything with a bit of flat surface on top is something to be landed on for a photo op). Note that if you move the Fido K with the kerbal on top, the Fido just slides out from under him and he falls to the ground (a very mild affair in the weak gravity of Minmus). Also below are pictures of Gergan on top of the Fido K's Carrier, and on top of the original Fido.
Now you may have noticed: The Fido K has no way to return our brave kerbals back home to Kerbin. So is this a one-way mission? No! We have another dog to help us get the crew back home when they are done joyriding on another celestial body: The Retriever. Here it is on its rocket.
Below is a test version of Retriever in Kerbin orbit (same as the final version except that I later added an RTG to the top to keep the probe body happy). The Retriever has five half-size Rockmax tanks: Two for the transfer out to the moon of interest; two for landing operations to give plenty of fuel to land near the retrievees; and one to get back to Kerbin, with fuel to spare. The side tanks can be dropped in sets of two as needed. The Retriever is controlled by the OKTO probe body on the top of the three-kerbal capsule so that it can potentially retrieve three astronauts.
Below, the Retriever settles in to Fido Base on Minmus. Its side tanks were still half full after landing.
The view of the Retriever out of the pilot's window of the Fido K... undoubtedly a very happy sight for the two kerbals.
Cammon Kerman did the EVA to the Retriever to check out its systems...and stand on top for a photo op. The ship has plenty of fuel left for even the sloppiest pilot to get it back to Kerbin. And, if the two kerbals ever get stranded away from base camp with a broken down Fido K, the Retriever has more than enough fuel to jump anywhere on Minmus to pick them up for return to Kerbin. Before the trip home, the probe body and its RTG can be decoupled from the docking port and left in orbit as a simple satellite.
So we leave the Minmus Fido Base with three Fidos, three defunct Carriers, and one Retriever ready to continue exploration operations.
The last thing I did was some experiments back at KSC to see if I could dock a Fido to a lander on the ground so that it could have its RCS tanks refueled from the lander. This involved mounting some docking ports on the vehicles in various places and then lobbing a lander (a Retriever powered by three Poodles so it could lift itself in Kerbin gravity) out into the field, and then 'launching' a Fido from the pad to roll over and dock with the lander. I DID get it to work, and transferred fuel from the lander to the Fido, but I could not get it to work reliably. If I hopped the lander, it would come down with slightly different amounts of flex or spread in its landing gear, so its docking port was not always at exactly the same height. In space, the program will nudge the ships around as needed to finalize the docking, but it can't do that with the ships on the ground. It would be nice if there was some sort of flexible connector with a little give in it that could make this kind of thing more reliable... or just a hose that a kerbal could run between the two ships to transfer fuel, as long as you get them some minimum distance apart. Below is a close-up view of the joined docking ports.
Here is the Fido docked to the other side of the Retriever docking test vehicle.