Kerbal Space Program

[Swagger897]

Dang, that looks awesome. Is that all stock?


There's a lot of the science missions I need to finish with planes but I just haven't ever liked building them.

 

[eran0004]

Dang, that looks awesome. Is that all stock?


There's a lot of the science missions I need to finish with planes but I just haven't ever liked building them.

I’m using the Airplane Plus mod, for the wings, horizontal stabilizers, landing gear, cockpit and passenger door/ramp. A big benefit is that it allows you to have fuel in the wings, so you don’t need an absurd amount of fuel modules in the fuselage. The mod also have a big selection of propeller engines, especially the turboprops are great for STOL aircraft since they are lightweight and have excellent thrust at low speeds.

Also, I’m using Atmosphere Autopilot to fly the missions. It’s not really necessary, but it makes it easier to fly efficiently without having to micromanage throttle and pitch all the time. You can set course, speed and altitude and then leave it to fly by itself.

And some advice for building:

1. keep the center of lift slightly behind the center of mass, that way the plane pitches down when stalling (which increases airspeed and helps you recovering)

2. place the main landing gear close to the center of mass, this makes it easier to rotate when taking off

3. place the tail as far back from the center of lift as you reasonably can, to increase the stabilizor effect and the torque of the elevators. If necessary, some fins at the front can help with elevation (but this reduces the effect of the stabilizers, so be careful).

4. pick a cockpit that lets you see what you’re doing (should have a good view of the instruments as well as the ground). It’s much more fun to fly from the cockpit, especially when landing.

5. If more lift at low speed is necessary, rotate the wings slightly to increase the angle of attack. Add flaps to occasionally increase it further.

Edit: Valentina took the new P11 aircraft out for a test flight. Bill the engineer came along to monitor some of the technical aspects, but quickly regretted his decision. Don't know what scared him the most - the actual flying or the expression on Valentina's face?

 

[eran0004]

New plane, the P12. Inspired by the BAe 146, it's powered by four small jet engines (which I have boosted by 50% to give it more realistic performance).

The BAe 146 can be seen in the wing design, the tail design, the 4-engine layout and the airbrakes at the rear. The tilted wingtips probably don't do anything good, they're just there because they look cool

Spoiler: [Insert Generic Clickbait Title Here]

As I was out testing it, I left it on autopilot for a while and when I came back it had got a lot further from the base than I had intended and with only about 1/3rd fuel remaining I was facing a big challenge: how to get the aircraft back to base before it ran out of fuel.

A quick calculation showed that at the current rate I would run out of fuel about 100 km from the runway, and although I had an altitude of 10,000 meters, it would probably not be able to glide that far (although I haven't actually tried gliding since the 1.4.x version, where I believe that they tweaked the drag calculations...).

By going to a lower altitude I could get more power from the engines and reach the runway faster, but it would also mean more fuel would be wasted on fighting the increased drag of the denser air as well as from the higher speed, so dropping in altitude would certainly reduce the range.

So if going to a lower altitude would reduce the range, my only hope would be to go to a higher altitude. By Kerbin standards, 10 km is pretty high up for a conventional aircraft and the risk was that the plane would have to pitch up so much that the increased drag would make it less efficient. At the same time, it operated nicely on 10 km with a full fuel tank, and at this point 2/3 of that mass had been burned so hopefully it would be able to climb another 1000 meters. Not that I had much of a choice - either take a chance of climbing or stay at the same altitude and eventually ditch in the ocean.

I started with a 5 m/s climb up to 10,500 meters, recalculated the range and came up 50 km short of the runway. Let it climb another 500 meters and recalculating once more the result was 10 km short of the runway. I was happy with that, since the fuel consumption would be reduced during the final descent. I picked a descent angle of 8 degrees, which gave a descent distance of 75 kilometers.

192.6 km from the runway, and less than 100 units of fuel remaining. It was nervous to see the fuel meter starting to measure in decimals.

Halfway through the descent. Runway in sight!

Final approach (landing from cockpit view is the best!). Since the tank was nearly empty I took the opportunity to test how slow the plane would fly. 40 m/s ias is pretty good.

Safely back on solid ground. <1% fuel remaining in the aircraft.

 

[eran0004]

What comes after P11 and P12? That's right, P13! This fighter-inspired jet performs so ridiculously well, which came as a surprise since I'm usually better at building slow planes. This beauty takes off at 45 m/s, toggles the afterburner and climbs to 11,000 meters where it accelerates to Mach 2, then climbs to 18,000 meters and reaches any point on Kerbin within an hour. It has some basic science instruments and can carry two drop tanks to extend its range. And aerodynamically I seem to have stumbled upon some golden sweet spot, where it has sufficient lift to land at 40 m/s and also minimal drag. I have to use the air brakes when approaching the runway, otherwise it picks up too much speed just from gliding.

Meanwhile in mission control, I had a bit of an Apollo 13 moment. Had two missions that involved going to the Mun. I didn't bother checking how much fuel I needed to bring, I just guesstimated some random fuel tank size when building the rocket and then launched without thinking twice. It was only when I landed on the Mun that I realised how little fuel I had left for the return back to Kerbin. Anyway, with some positive thinking ("the tank is 10% full, not 90% empty...") I decided to give it a go anyway, so I launched into the lowest orbit I dared to and then when I came to the side facing Kerbin I burned prograde just enough to leave the Mun's sphere of influence.

Then I found that my escape trajectory gave me an orbit around Kerbin with a fairly high apoapsis, so I waited until I reached that apoapsis so that I could use my delta V as efficiently as I possibly could. What I found was that with a relatively small burn I could rendezvous with the Mun again and use it to as a slingshot to get an absurdly high apoapsis (79.7 million meters above Kerbin). That seemed to be my only viable option, so that's what I did.

Screenshot from when I planned the burn to almost send me out into deep space. Only costed me a delta V of 34.3 m/s to almost triple the height of my apoapsis.

The gravity turn was a success! Here I'm heading out for a long journey towards the new apoapsis. Next burn is already planned, it will be a 79.4 m/s handbrake turn to stop the spacecraft almost entirely and then letting it fall back to Kerbin. Looking at the fuel tank however, there's not much left in there at all. What happens if Valentina runs out of fuel 80 million meters from home?

The fuel didn't run out! But with <1 unit remaining, you can talk about balancing on the knife's edge! The periapsis of <30 km should be enough to capture the spacecraft, had to burn with a thrust limiter of 1% to get the kind of precision needed to avoid slamming into the ground.

The re-entry was a piece of cake. After touching down, Valentina got picked up by the new P13 aircraft and taken back to base at supersonic speed for debriefing and a shower (it took 58 days to get her back from the Mun!)

 

[eran0004]

This compass just caused me a crash at the end of a long mission

See what the problem is?

 

[eran0004]

The success of the P13 led to the spaceplane version P13 X. This version has the jet engine replaced by a rocket engine and it has two pairs of boosters attached to the wings. It also has an increased crew capacity, carrying up to four kerbals.

T+3:35 - launching towards Minmus to retrieve some valuable scientific data and give the crew an experience boost.

^ 20 days later: returning to Kerbin in a polar orbit. Valentina and Bill are enjoying the view,
while Bob seems more nervous, hoping that atmospheric braking at 3 km/s
won't turn into atmospheric breaking...

^ Bob had cause for his concerns. But after reloading the quicksave half a dozen times and trying out some different braking
configurations the spacecraft actually survived the re-entry and here it can be seen gliding towards the runway.

Safely back on solid ground. Beautiful landing!​

 

[TenEightyOne]

This compass just caused me a crash at the end of a long mission

View attachment 737845

See what the problem is?

That's crazy, can you fix a texture for it?

 

[eran0004]

That's crazy, can you fix a texture for it?

I doubt it. But at least I know now not to trust the IVA compass.

Here's my latest contraption - the P14 - inspired (well, my kerbal engineers basically stole the blueprints) by the Saab JAS 39 Gripen. I'm always surprised when real world plane designs work well in KSP, I guess I underestimated the amount of realism that this game offers in atmospheric flight. The performance (range, speed, stall speed, turn rate) is even more or less the same as the real plane

^ Made it around the world in less than 2 hours.

^ Even stole the airbrake configuration from the JAS 39

 

[eran0004]

In this episode of "eran0004 replicates the Swedish Air Force in Kerbal Space Program" we go back to 1951 and the Saab J 29 "Flying Barrel"!

The real aircraft has a thrust of 27 kN, so for my KSP build I picked a modified J-20 "Juno" engine which outputs 30 kN. I tried to replicate the body and the shape of the wings to the best of my ability. My version is a bit more slim than the original though, and the air intake is enormous by comparison. Other than that I think it's pretty close.

The plane is extremely agile thanks to the center of lift being right on top of the center of mass. I could to aerobatics over the space center all day long (and so could Valentina, judging by her facial expression)! The performance is pretty much spot on with the J 29, although my version has a slightly higher top speed. The range is more or less identical.

^ Center of lift is pretty much at the center of mass. Most of the fuel is at the center of the plane, to prevent the center of mass from shifting too much as the fuel is consumed.



Edit: Fixed the nose! Replaced the huge air intake with an FL-A10 adapter and a small air intake. Looks much better!

 

[eran0004]

Saw a Scott Manley video where he did air combat with the BDArmory mod, so I decided to try that myself.

Here is my (surprisingly accurate) Saab JAS 39 Gripen replica equipped with a pair of Sidewinders, two S-8KOM Rocket Pods and two cruise missiles. It also got a targeting pod and an inline radar module.

Deploying first cruise missile against the marked target.

Second cruise missile ignites, following the trail of the first missile.

Approaching the target, Valentina adds a couple of rockets from the 8-SKOM pods. Can't hurt, can it? Bill just realised that he parked his car behind the very same hangar that Valentina is aiming at.

So far it looks like a pretty fun mod. Haven't figured out how everything works yet, but it was a good test run.

 

[eran0004]

Installed a "real solar system" mod.

Initial thoughts: It's much harder to reach orbit! For Kerbin you need about 2.3 km/s to reach orbit, while for Earth you need about 7.5 km/s. Took me half a dozen attempts to get the right amount of fuel and thrust.

In the end I made it though, and decided to fly from Florida to Australia - a journey that took just over an hour to complete.

^ View from the cockpit, while flying in orbit over Madagascar.

^ Having completed the re-entry burn, the spacecraft heads back towards the atmosphere. Australia just appeared at the horizon.

^ The crew had to endure a maximum of 10 G during re-entry. Bob and Bill both passed out after a few seconds.

 

[eran0004]

Decided to fly to the Moon and back. In a maneuver I call "jumping in front of the bus" the spacecraft flies past the Moon's orbit and then as it turns back towards the Earth, it crosses right in front of the Moon, travelling at approximately 1 km/s, at a distance of only 17 kilometers. The Moon then slingshots the spacecraft further out into space and then at the apoaps of it's new orbit around the Earth, it pulls a very fuel economic handbrake turn and returns to Earth.

Below: Setting up the "jumping on front of the bus"-maneuver.

Below: The spacecraft, about to make the jump. From left to right: The Moon, the Sun, the Spacecraft and the Earth.

Below: The periaps was a complete gamble. I don't know how big the mountains of the Moon are, and I wasn't sure how accurate the "Real Solar System" data would be. On the map, it looked like the trajectory would possibly intersect with the surface of the Moon...

Below: The trajectory was all good, though. And I got to do an Apollo 13 style slingshot around the Moon, which was awesome!

Below: Setting up the handbrake turn that will return the spacecraft to Earth. A periapsis of 45 km should be enough to bring the spacecraft to a halt.

Below: Heading back towards the Earth. Speed is gradually increasing...

Below: Antarctica and New Zealand welcoming the spacecraft home.

Below: Final stage separation before re-entry.

Below: "Flat Earth"? Yeah, right...

Below: Passing over what I think is Easter Island. Still some 200 km above the atmosphere, and speed is approaching 11 km/s.

Below: The heat shield doing its job. Perhaps the re-entry was a bit steep, 12 G worth of atmospheric braking is quite a lot to endure when you've been in space for 44 days...

Below: The monstrosity needed to launch a spacecraft towards the Moon at real solarsystem scale. The solid rocket boosters look tiny compared to the custom made liquid fuel boosters... The design is obviously inspired by the Delta IV Heavy launch vehicle. Quite funny to think that the payload is just the tiny can at the top.

Below: During launch. Nozzle count: 22 (4 for the main engine, 14 for the liquid fuel boosters, 4 for the solid rocket boosters).

 

[eran0004]

Found the cutest little jet fighter on Wikipedia and decided to try to build it in Kerbal Space Program.

Spoiler: McDonnell XF-85 Goblin

I was expecting it to be difficult to build since it doesn't really have a tail, but to my surprise the first attempt flew perfectly fine! The only aerodynamic issue was a slight yaw instability.

The biggest issue was the landing gear, because the nose kept bouncing violently on touch down and led to crashes in 9/10 attempts. At first I tried adjusting the spring and damper settings, but it didn't really solve the issue. In the end I found that the likely culprit was that I placed the nose gear at an angle (rather than pointing straight down) because after changing the angle the problem disappeared.

It's great fun to fly! The only mod needed to build it is Airplane Plus, since it has the wings which can carry fuel as well as the short landing gears.
I also recommend Atmosphere Autopilot, to enable fly-by-wire controls (so you won't have to constantly adjust pitch when you fly with keyboard controls).



Edit: Had a little excursion along the coast of Florida. With a half-empty fuel tank the Goblin makes it up to 14,600 meters, which greatly extends the range.

Some screenshots below. On the third image you can see Cuba across the sea. Didn't have enough fuel to go there, sadly...

 

[eran0004]

I quite like making these micro planes. It's a nice challenge to try to make them as compact as possible. This one turned out pretty good, it can climb vertically, do up to mach 2 in horizontal flight and pull many many G's in the turns. In fact, it kind of slides through the air, like drifting in the sky

The only minus is that the stall speed is relatively high (70 m/s), so the landings can be a big rough.



I also made a high altitude supersonic plane, which I have aptly named "firebird".

 

[eran0004]

I'm currently reading Jim Lovell's "Lost Moon", so I decided to build an Apollo-style spacecraft with a lunar module and a command module.

First stage: 6000 kN
Second stage: 1500 kN
Third stage: 60 kN
Lander Module: 8 kN (+4 kN RCS thrust)

First stage takes the spacecraft out of the atmosphere, while second stage is for orbit injection. Although, since I reverted to stock world scale, I found that the second stage had so much fuel that it could go all the way to the Mün and get into orbit. Once in orbit around the Mün, stage 3 decoupled, brought out the lander module and docked with it. Unlike Apollo my lander module only had room for one kerbal, so I had one pilot and one engineer staying in the command module, while the second pilot took control of the lander module and begun the descent to the surface.

I decided to power the lander module with four "ant" engines (total force of 8 kN) in order to save weight, and it turned out that it was just enough to land safely. With three engines I would have crashed, and with six engines I would probably have run out of fuel.

Upon ascending from the surface, I hugged the ground and burned almost horizontally to get the most out of the delta-V I had, and after expending the last bit of fuel (including the monopropellant) I got to an altitude where I could rendezvous with the command module.

Meanwhile at the command module it was a race against the clock to catch up with the lander module before it peaked in its trajectory and returned to the surface. Since the lander was out of fuel it meant that I had no choice but to take the command module out of orbit for a few minutes during rendezvous and docking, and then power up and away before crashing into the ground. Fortunately the command module was well balanced and easy to control, so docking was relatively fast. Transferred the pilot and the research data to the command module, then undocked the lander module and burned prograde to escape the Mün and return to Kerbin.

I had a ton of fuel left in the third stage at the end of the mission, so the spacecraft is probably able to go much further out in space. Preferably to some asteroid or that smaller moon (whatever it's called) given the tiny fuel tank and engines of the lander...

 

[eran0004]

Yet another jet fighter. This time an F/A-18 Hornet.

Using tweakscale I'm trying to get the engines just right, but I'm still missing 10 kN each. Landing gear needs to be scaled up slightly as well.

Edit: Created my own custom version of the engine and tweaked the stats to match the real aircraft.

Here's the Hornet in action.

 

[eran0004]

New land speed car.

 

[eran0004]

Today I downloaded the new 1.7 release, started building a space station in high Mün orbit and tested a mushroom escape pod.

 

[eran0004]

So I built this SSTO (single stage to orbit) spaceplane. It flies extremely well, very easy to control in the atmosphere and at 40 km it can "surf" on top of the atmosphere while bleeding very little energy. It reaches orbit with 900 m/s delta-V to spare, so with some small tweaks it might be able to reach the space station in orbit around the Mün. Probably not with a lot of payload though, it would be more like a sportscar for space...

 

[eran0004]

I played this game for a couple of years now, but I never made an expedition to Duna. Until now

I opted for an Apollo style spacecraft. A command module for three kerbals coupled to a lander module for two. I carefully studied online sources for how much delta V I needed to bring for the ride, but ended up eye-balling it anyway. In the picture above it's the spacecraft attached to the second stage of the launch vehicle. If you have an eye for details you might be able to spot one rather crucial design flaw... more on that later.

Successful rendezvous with Duna! Using gravity assist from it's moon Ike to get into position for an aerobrake maneuver. The second stage brought me all the way here, and as a reward I gave it a space viking funeral (basically I tossed it at Ike and watched it impact the surface at a speed of 2 km/s).

Aerobraking at Duna. The atmosphere is really thin, so those flames aren't as hot as they seem to be.

The aerobrake was followed by an orbit circulation burn and then the lander detached from the command module and begun its descent towards the surface.

Successful landing (after quickloading following a less successful attempt). The Duna landscape was impressive, I'm sure I will return again!

Rendezvous with the command module after launching from the surface. Judging by the fuel meters, I'm pretty good at eyeballing the amount of fuel I need to bring!

The lander has been ditched. The spacecraft swings around Ike once more for a gravity assist slingshot to take it back to Kerbin.

Upon returning to Kerbin I realised my design flaw. While I had remembered to bring parachutes for the lander module, I had forgotten to attach some on the command module. Oops. At first I contemplated putting the spacecraft in orbit around Kerbin and launch a rescue expedition to bring them safely back home. Unfortunately I did not have enough delta-V for a circular orbit and I figured a highly elliptical orbit would be rather awkward for a rendezvous, so I just opted to drop the command module into the atmosphere and have my three kerbals eject and use their personal parachutes.

Safely back on terra firma. Unfortunately nowhere near the space center.

The KSC sent a SAR plane to find and retrieve the three kerbonauts.

Although the kerbals were stranded on a rather steep and un-runway-like hillside, the aircraft - designed with STOL capabilities in mind - was able to land and collect them. Two hours later they arrived safely to the space center, and that's the end of the mission.

 

[eran0004]

For a while now I've been wanting to land a probe on Laythe, one of Jool's moons. The motivation has not been science or exploration, I just wanted to see what Jool looks like from such a close distance.

The problems I've faced in the past are three:

1. Jool is so far away that any mission there takes a long time to run (even with time warp). The probe and the spacecraft needs to be really well designed, because if something goes wrong near the end of the mission I just wouldn't feel motivated to start over.

2. A Jool encounter is a high velocity business. In my last attempt to land at Layhte I accidentally approached it head-on in its orbit around Jool and entered the atmosphere at around 8.5 km/s, instantly evaporating my probe. What makes it even more difficult is that a spacecraft with enough delta-V to get to Jool usually have a low thrust-to-weight ratio, meaning critical burns are counted in tens of minutes rather than tens of seconds.

3. Leythe is mostly covered by ocean. Finding solid ground for a landing zone is not easy.

The first problem can't really be solved. Just need to think carefully about the build and remember to add parachutes.
The second problem can be solved, with some clever maneuvering and gravity assist burns.
The third problem is solved most easily by landing at one of the poles. That way, you have a stationary target to aim at.

Below are some screenshots from today's attempt. Fortunately(!), I don't have any good pictures of the actual spacecraft, but I can tell you that it was... unfortunately shaped. It was powered by a nuclear engine using liquid fuel and had about 9000 m/s delta-V.

First: On final approach, coming in hot at around 2km/s and preparing to separate the final stage. Landing zone in sight. As you can see it's almost four years after the launch...

Second: Parachute deployed. Dropping gracefully towards the polar cap. In the background, the amazing view of a gas giant lurking at the horizon. One of its moons is also visiable.

Third: Successful landing. Antennas and solar panels extended. I landed slightly off-center relative to the pole, so technically it's "night" in this picture - at "day" it's a little brighter and the solar panels actually get some sunlight.

To summarize: Successful mission, I'm happy I was able to pull it off.

 

[BKGlover]

I was playing this again. I swear I'm not trying to be incompetent 🤬, but the only thing I've managed to replicate successfully is me screaming at the game because nothing I'm doing is changing anything except how fast everything dies. No matter what, by the end of the session (just before I take a chainsaw to my PC) I cannot get whatever I'm on off the ground before it dies. FFS, I had a single function rocket launch, spin over, and crash in 15 seconds.

Sorry, had to vent.

 

[Swagger897]

I was playing this again. I swear I'm not trying to be incompetent 🤬, but the only thing I've managed to replicate successfully is me screaming at the game because nothing I'm doing is changing anything except how fast everything dies. No matter what, by the end of the session (just before I take a chainsaw to my PC) I cannot get whatever I'm on off the ground before it dies. FFS, I had a single function rocket launch, spin over, and crash in 15 seconds.

Sorry, had to vent.

lol, make sure you're using SAS for maneuvers. It will dampen the controls a considerable amount and act as a hybrid auto-pilot for control augmentation.

 

[BKGlover]

lol, make sure you're using SAS for maneuvers. It will dampen the controls a considerable amount and act as a hybrid auto-pilot for control augmentation.

I did. SAS and RCS were active. Even after I'd go back to an older design that worked, the still kept failing.

 

[eran0004]

I did. SAS and RCS were active. Even after I'd go back to an older design that worked, the still kept failing.

How old are your older designs? I know that they changed the aero simulation some time ago, so maybe you have some bad aerodynamics, such as center of drag in front of center of mass.

 

[BKGlover]

In game, hours. And like I said, they will have worked as intended at least once already.

 

[eran0004]

In game, hours. And like I said, they will have worked as intended at least once already.

Strange. In what way do they fail? Do they break apart or flip around?

Edit: if you have many parts to your craft, you can try the autostrut feature (I think you can enable it in the options menu). This allows you to set automatic struts between the parts, which makes the craft more rigid and less floppy.

 

[BKGlover]

Strange. In what way do they fail? Do they break apart or flip around?

Rockets go up then start flipping over, even with all assist on. Planes either disintigrate on the runway or backflip into death spiral.

 

[eran0004]

Rockets go up then start flipping over, even with all assist on. Planes either disintigrate on the runway or backflip into death spiral.

First case sounds like center of drag is higher than center of mass, alternatively that the rocket is bending during ascent, pulling center of mass away from the thrust vector. If it’s the first, attaching fins to the tail of the rocket should help. For the second, add more struts (or autostrut), especially between the heavy parts.

The plane thingy sounds like an issue I had with the Airplane Plus mod, where the gear would cause a backflip. You can try loading the craft with the gear retracted and then extend the gear once it’s sitting on the runway.

If that doesn’t work it could be some weird physics glitch, you can try restarting the game and see if it helps.

 

[BKGlover]

I'd wager it's either a glitch, or the software overcompensates after I've been playing a while because the rockets aren't that big and do have fins.