Jouni

I had some more time to play KSP, so I returned to my Tylo expedition. Starting from 5N, I soon crossed the equator. Which was conveniently drawn on the ground. My rover driving skills keep improving all the time. I also realized that if I remap rover controls, prograde SAS can keep the rover under control in seemingly impossible situations. At around 30S, the mountains started getting higher. I climbed to the highest nearby peak, which was 9911 m above the baseline. That was a mistake. Behind the mountain was an utterly ridiculous crater. There was no way I could descend into it, so I had to go around . Eventually the crater rim became too narrow to drive. I tried traversing the crater wall, but soon the rover was heading down. That was the quickest kilometre I have ever descended in a rover. SAS performed its miracles, and I only broke three wheels. The altitude is still almost 7.5 km, so I'm nowhere near the bottom. It will probably be the best to head southwest and cross the crater rim at a point where the slope is more gradual.

I continued my Tylo expedition and managed to drive another 250 km towards the equator. How wheels work in KSP is still beyond me. What I know that if you make small turns while accelerating, the rover reaches much higher speeds. When I reached a large flat area, I decided to try how fast the rover can go. I reached 160 m/s before making the small turns became too hazardous. After a minute or so the rover hit a small bump and crashed. I reloaded, increased wheel traction, and crossed the flats at a leisurely 100-110 m/s. The increased traction also made the rover more stable. I can now drive safely 60-70 m/s over rough terrain. Today's trip ended on another crater rim a few degrees north of the equator.

I continued the Tylo expedition. Moving fuel from the ascent stage to the descent stage lowered the CoM enough that the rover remained controllable at speeds up to 50-60 m/s. Sometimes I could even recover after losing control at 75 m/s. But not without breaking a wheel. Driving 200 km/h in heavy rover with underdamped suspension isn't exactly a smooth ride. Especially when the passenger compartment sways wildly every time the rover hits a bump. I drove around 100 km south from the cave and climbed to a crater rim rising 2 km above the surrounding plains. It's still over 300 km to the equator, but there doesn't seem to be anything interesting on the way there.

While I have landed on Tylo many times, I have never explored the planet. Today I decided to change that. The expedition required two launches. The first was my standard interplanetary ship. As the ship wasn't carrying any heavy payload, there was no need for the usual booster contraptions. Just two standard heavy boosters, with one additional Vector each to get the TWR above 1. As the thermal control systems were dangerously close to the boosters, I had to rotate the ship to get rid of the boosters safely. The second launch had a weird fairing protecting the payload. As the transfer stage was non-nuclear, I needed six heavy boosters to lift it. The payload was a huge rover. The rover took a fast route to Tylo, while the mothership arrived around 100 days later. Because I intended to land near the cave, I put the ships into an orbit with a 50-degree inclination. The crew boarded the expedition module... ...and took it to the rover. Meanwhile the mothership moved into a 1000 km orbit to relay communications between Kerbin and the rover. The Vector is a convenient engine for Tylo landers, though the gimbal range is way too high. I usually limit the range to 30% of the maximum to keep the ship controllable. Everyone on the surface. The ladder must be on the uphill side of the rover, or the kerbals have a hard time climbing on top of the fuel tank. The rover can go over 60 m/s downhill, but you can't brake or steer safely beyond 30-35 m/s. The kerbals are clearly enjoying the ride. First destination reached. You can see the rover in the middle.

A reentry in a command pod is quick, but it's hard to hit anything smaller than a continent reliably. Spaceplanes take forever to land, but you can choose your landing site precisely. Today I tried an intermediate reentry vehicle that can land reasonably quickly and reasonably accurately. T+ 13:57: The craft enters Kerbin's atmosphere at 1.95 km/s with descent rate 0.59 km/s. Soon it is enveloped in flames. T+ 15:06: I deploy the elevons momentarily at 25 km. The craft is currently moving at 2.11 km/s with descent rate 0.68 km/s. The result is a bit extreme. T+ 15:31: I regain control at 16.5 km, as the craft decelerates to subsonic speeds, and start diving towards the landing zone. T+ 16:39: I deploy the elevons at 2 km above the surface to kill the descent rate before landing. T+ 17:00: I deploy the parachutes at 400 m above the surface. They are set to deploy fully at 100 m. T+ 17:06: The craft lands in a safe and comfortable manner 3 minutes and 9 seconds after entering the atmosphere.

I completed a simple Apollo-style mission. This probably isn't the right way to land on the Mun. 189 days later... Finally managed to land somewhere. Taking off with RCS. A year and a half later.

I launched another copy of my Vall ship, with reduced oxidizer for the VTOL engines this time, and headed for Eeloo. Or, actually, because I hate waiting for launch windows, I took advantage of the Jool window opening in 14 days. A few years later... The drop tanks lasted almost all the way to the surface. Because I dropped them at a low altitude, large parts of them survived. There was another piece of debris a few kilometres away, so Jeb went to investigate. Meanwhile back at the ship... Wait, where did that other fuel tank go? Now it's also falling from the sky! It's raining death over here! Finally things had calmed down enough that the crew could come out and investigate. I still don't know what happened to the drop tanks. And then it was time to go home.

I use RCS, because docking is much more fun that way. Instead of just ramming the target ship, you maneuver the ship precisely into position, and then approach at ~5 cm/s.

It was time to clean up the space near Kerbin. I launched a few deorbiters to get rid of the debris that earlier launches had left in orbit. KSP physics go weird, if you release the pivot of the klaw for reentry. The Mammoth acted as a heat shield for most of the reentry, before ultimately exploding and releasing the deorbiter. The deorbiter survived the reentry... ...but not the landing. The craft bounced off the ground a few times, losing new parts every time, until only the klaw was left. It didn't look exactly right, though.

Duna is an annoying planet. It's easy enough that you can have other design goals than just functionality. There is an atmosphere that makes most landers unusable, but the atmosphere is too thin for reasonable planes. This time I launched a fairly simple mission: boosters, a lower stage, an upper/transfer stage, and a lander/return ship. The fairing looks a bit weird, as it's actually two separate fairings. The lander has a weird tower for no real reason. The inflatable heat shield is a useful airbrake for Duna landers. Jeb, Bob, and Val are posing, while Bill repacks the parachutes in the tower. Bob also went to see the giant face. Most of my recent missions have been visiting the easter eggs I haven't bothered to visit before. Back on Kerbin. The tower lander works quite well during reentry and has more than enough parachutes for a safe landing.

Another day, another moon. All my heavy launch vehicles tend to have two Mammoth sustainers and two Twin-Boar boosters these days. The ship itself was smaller than usual, as it was supposed to land on Vall on its own. I had never seen the Vallhenge before. It was much larger than what I expected. The same four kerbals as always. I had to use two Thuds as VTOL engines. The gravity on Vall is too strong for the uphill landings I use on smaller moons. Time to go home. In order to accommodate the VTOL engines, the ship had smaller than usual fuel tanks. While my typical Jool exploration ships have 10 km/s at LKO, the Vall ship only had 8 km/s. That meant an interplanetary launch directly from a Vall orbit with a 60-degree inclination, and aerobraking for over 1 km/s at Kerbin. The usual crew recovery with a spaceplane. I overshot the runway by 100 km and had to fly back, as I had no idea how to return from an orbit with a 24-degree inclination.

That 0.5g minimum acceleration is also something you rarely need outside landers and launch vehicles. One thing I noticed after my 1.5-year break is that I could do almost any maneuver reliably under 4x physics warp. I have a faster computer, KSP is better optimized, and SAS behaves better than before the break. There are no longer 15-minute burns, as any burn can be done in less than 4 minutes of real time with 0.2g acceleration. The temptation to add more engines because of my impatience is no longer there. Chemical rockets are good, if your destination is no further than Eve or Duna. Beyond them, even an one-way trip takes more than 3 km/s, and you start requiring an excessive number of stages for the mission. Ships get complicated and fragile, and you spend more and more time on tweaking the routine stuff.

The loss of efficiency is marginal. If you do a single burn from LKO to Jool with (Kerbin) TWR 0.2, you spend maybe 2200-2400 m/s of delta-v instead of the optimal 2000 m/s. On the other hand, a typical nuclear stage produces 6000-7000 m/s, while chemical rockets only produce around 3500 m/s for the same payload and mass. For landers, the sweet spot is usually around (local) TWR 1.5. Beyond that, you spend more fuel for carrying the additional engines than you save from the higher TWR. On Tylo, the optimal TWR might be as low as 1.0.

After Bob had confirmed that the Kraken was really dead, Val drove the ship closer. Then it was time for the return trip. My original plan was to make the ship VTOL capable on Bop, but that would have required too much fuel. The actual takeoff was a crazy run uphill, with SAS off for faster reaction times in keeping the ship from rolling over. As the hill became less steep, a short RCS burn was enough to lift the ship off the ground. The return trip was uneventful. After reaching LKO, I used my new crew shuttle to recover the crew. It still didn't fly as well as I wanted, but switching the inner elevons from pitch to trim made the landing much easier.

There are three issues here. First, the visual effects are intentionally exaggerated, because the orbital speeds are so low. If we want to see reentry flames when returning from LKO, we will also see flames during shallow ascents. Second, we have a 80% scale model of Earth's atmosphere on a planet 9.4% the size of the Earth. Our ascent paths are necessarily shallow, and our rockets go faster than real rockets at comparable altitudes. Third, our low orbits are really low. The ISS orbits at 400 km, which would be 320 km over Kerbin. Yet we routinely launch to 100 km, which makes our shallow ascents through the atmosphere even shallower.

Alien life was discovered in the system. Kerbals launched a quick mission to investigate. I basically took my Tylo mothership, moved the drop tanks further back, replaced the lander with a lab, and moved all fragile parts inside the cargo bay. After discovering the dead alien, Jeb landed on the other side of the ridge to be safe. And because the mothership can only land uphill reliably. Descending to the valley. The cargo bay was closed to protect the fragile parts. It was a bumpy ride. The ship accelerated to 12 m/s on the way down, bounced from the valley floor, and spun wildly around all axes before finally landing down. Jeb blamed the Kraken and parked the ship at a safe distance. Then everyone went out to investigate.

I went to the Mun because it's there, and because it's the closest place you can test new designs. The rocket didn't look too reasonable. Approaching the Mun. I've liked ion landers since the ion engines were made ridiculously powerful in 0.23.5. They make no sense, but they make everything more interesting. Even a Mun landing starts resembling a Tylo landing. The kerbals always just plant a flag and return home. I barely managed to charge the batteries before nightfall. There were a lot of explosions during the reentry.

I was testing small rockets, which I usually don't build. One of the tests involved a manned flight beyond the orbit of Minmus and a direct return to Kerbin. After the capsule barely survived aerobraking, I noticed that it was going to land within a few kilometres of KSC. I decided to steer the capsule to land at the space center. I didn't manage to hit the VAB or the launchpad, but at least Jeb landed home.

@KerbalNetwork I haven't really built 1.25 m rockets since 1.0.4 or so. My general impression is that the Reliant is a booster engine, the Swivel is a first stage engine, and the Terrier is an upper stage/vacuum engine. Using the Reliant in the first stage is a bad idea. The engine doesn't have thrust vectoring, so you need something else for steering the rocket during the ascent.

Most of my rockets are 2.5 m, 3.75 m, or Mk3, as I almost always play sandbox. I also prefer simple designs, so I tend to avoid complex engine clusters and interstage structures. For launch vehicles, I have three basic configurations: lower stage + upper stage, lower stage + boosters, and lower stage + payload engines. Boosters require a high TWR and a high sea level Isp, so the appropriate engines are the Vector, the Mainsail, the Twin-Boar, and the Mammoth. First stage engines have similar requirements, but if the boosters are large enough, the Skipper and the Rhino can also be useful. For example, my recent Dres mission was launched with two Twin-Boars and a Rhino: Upper stage engines and other vacuum engines require a decent TWR and a high vacuum Isp. The Poodle, the Skipper, and the Rhino are appropriate for my typical payloads. Finally, small engines such as the Spark and the Terrier are the best for landers. Large engines tend to make the lander tall and unstable, and you rarely need that high TWR anyway.

I built a serious crew shuttle. The old one was rather silly, after all. The plane is not too bad on the ascent. It also looks decent, though the RCS thrusters are too exposed for my taste. It can also dock with my typical interplanetary ships, fulfilling its purpose. The descent is worse, though. I can either pump some fuel from the rear tank to the forward tank to make the plane very stable during reentry, or I can keep the fuel where it is for an easy landing, but I can't achieve both. That's why I don't like planes.

I usually start Tylo landings from a 30 km orbit, and begin the final burn at around 20 km. The idea is to keep the descent rate at around 100 m/s. This gives you around three minutes to get rid of both horizontal speed and altitude, and then you can land without spending too much fuel for controlling the vertical descent. If you start too low, you may crash because you can't kill the horizontal speed in time. On the other hand, if you start too high, you may kill the horizontal speed too soon, and then you may run out of fuel during the vertical descent.

I went to see another old runway of mine. So far so good... Now it's pointing the wrong way. This is what the afterburner is for. And a takeoff!

I don't like planes. No matter what I do, they always fly a bit wrong. So when I build planes, I make sure they have enough engine power to overcome the lack of precision. I also miss the early patches of 1.0, when planes could easily land anywhere. I used to have an airfield on the summit of the steep mountain near KSC. Now it's much harder to get there without crashing or overshooting.

My Tylo crew was still in orbit, so I needed something to get them back home. I chose an improved version of my crew recovery ship from 1.2. It still doesn't look exactly right. At least the parachutes are now properly balanced.