Seven!

Today marks the end of the seventh year of the blog. I say this every year, but it’s crazy to me that the blog is still around after so long. Of course just like last year, my posting has been sparse outside of Blaugust, so the blog is really barely around. I’m at the point now where it’s nice to have an outlet when I need one, but I don’t feel guilty when I look at the site and see it’s been four months since I wrote anything.

I’m not saying that I expect to fall silent until next year though. I’ve got a weekday reminder to write something set on my phone and that has worked more often than it hasn’t in September. My hope and my goal is to keep that up with two or more posts a week depending on what I’m doing and how much I have to say. If nothing else I expect to have regular KSP mission reports.

Thanks to everyone who’s stopped by to read or comment, I’m looking forward to seeing what the next year brings.

Model Rockets

Estes Rocket KitThings 1 and 2 watch me play Kerbal Space Program occasionally and I’ve been trying to get them interested in space by showing them YouTube videos of real rocket launches and interviews with the astronauts on the space station. Somehow last week the topic of model rockets came up and it got me thinking about trying that out, because of course I need yet another hobby.

I stopped by the local hobby store on my way home last Friday and picked up an Estes rocket kit, engines, and recovery wadding. Model rocket kits come in various skill levels. The one I picked up was an E2X, which means easy to assemble, and basically just required gluing parts together. There’s two levels below that RTF for ready to fly and ARF for almost ready to fly which require no or very little assembly, and then there’s Skill Levels 1 up to 5. The E2X was about perfect for the level of effort I wanted to put into things. It required some basic assembly skills and model glue. I was able to put both rockets and the launcher together in about an hour.

Rocket Assembly

Lost Sky DartOn Saturday my dad and I took the boys to a nearby nature preserve (basically a field/trail left to grow wild) that was usually not busy and picked a corner to set up the launcher in that would put us upwind of an open field. We started with the smaller of the two rockets, the Sky Dart, and had three great launches. Unfortunately the orange streamer come off on the first flight. We were able to track it and recover it on the second launch and should have stopped there until I could get some orange tape or ribbon to replace the lost streamer. The third launch neither my dad nor I could track after it went up and we never were able to locate where the rocket came down. The weather started to sour on us about than anyway, so we packed up and headed home for a few hours.

Farside RocketWhen things cleared up in the afternoon, I came back with just Things 1 and 2 to try out the remaining rocket from the kit, the Farside. It was quite a bit larger and had a parachute on it, so I figured it would be easier to track and recover.

The first launch I forgot to take the little orange cap of the top of the launch rod. The rocket took care of that for me, but it only went up about 20 feet and it veer sharply to the right. So it turns out our position with respect to the wind was good for more than just keeping the rocket from landing in nearby trees, as it kept the misfire headed away from us rather than towards us. The boys of course thought it was hilarious.

The second and third launches went great. The Farside didn’t get the same altitude as the Sky Dart and was far easier to track even without the parachute. I had some issues getting the parachute rolled up right. It deployed fine on the second launch but seemed too tangled on the third and final launch. There’s definitely some skill with that and getting the recovery wadding packed right inside the rocket. The wadding is important as it’s a non-flammable kind of tissue paper that is supposed to protect the chute and nose cone from the second charge that fires after the rocket launches. This charge is supposed to pop the nose cone off and push the parachute out so it deploys near the apogee of the flight path. The problem is if you put too much in, then the chute might not fully deploy. Put in too little and you can end up with a brown singe spot on your parachute. So there’s definitely some skill there that I need to practice.

It was a lot of fun and unlike some of my hobbies, doesn’t require a lot of time at least at the level I’m currently at. I’ve already ordered a small rocket to replace the lost Sky Dart and a bunch of new rocket engines. I’m looking forward to flying them again soon.

Bop Transfer

JE1 Tylo to BopOver the weekend I returned to my Jool exploration mission and got the Explorer transferred from Tylo to Bop.

It took about two hours of real time and required three burns. A 10 minute burn to leave Tylo, a 6 minute burn to match inclination with Bop’s orbit and get an intercept, and a final 6 minute burn to get into orbit around Bop. Docking turned out to be easier than I expected but was quite slow.

Overall I’m pretty disappointed with the VASIMR engine on the ship. I tried an alternate design in the VAB with two reactors and engines which did help with the TWR of the craft but not enough to offset the hit to the available deltaV. Instead, I’ve started looking at a new version of the Explorer that uses nuclear engines. The current design looks very promising. It has better TWR and roughly the same deltaV. The ship is smaller because nuclear engines run on liquid fuel not hydrogen which takes more volume, and there’s no nuclear reactor required which saves a lot of mass as well.

Speaking of mass, I drastically overestimated the amount of supplies I would need for the crew. Or really I under estimated how well the hydroponics modules would do at recycling waste. Three years into the mission, and the crew still has a full set of supplies. The next mission should easily be able to get away with half the number of supply containers or more.

So now that the Explorer is docked at the refinery I have to make a decision about whether to cut the mission short and return to Kerbin or continue on to Pol, Laythe, and Vall. I’m leaning to cutting things short and coming back to Jool with a redesigned Explorer with better TWR. Either way, I can send Jeb down to the surface as planned and then leave the lander at the refinery.

Bop Refinery Approach Bop Refinery

Iconian War Finale

Midnightsto_midnight, released yesterday, is the eighth and final episode of the Iconian War story arc in Star Trek Online. I got a chance to play it last night, and I think it’s my favorite episode in the entire game. It felt like a good TNG episode. I don’t want to spoil the mission for anyone but let me say that this entire arc has been great for resolving plot lines that were left hanging in TNG and Voyage.

Congratulations to Cryptic not just for a great episode but for finding a good release cadence for story missions. This year had seen a lot of quality new content released. Having a combination of monthly new episodes with rewards becoming available on a weekly basis to promote replays strikes a nice balance of giving players new content without overloading the developers. I can’t wait to see what’s coming with the next Season.

If you miss having Star Trek on TV, you really should give the game a try. The only downside is that the Iconian War arc is for level-capped players, but it’s possible to get to 60 pretty quickly between XP boosts and the Duty Officer system.

Tylo Landing

Continuing my extended weekend in KSP, I left off yesterday with the crew of the Jool Explorer 1 starting their two year journey to the outer edges of the Kerbol system. I time warped the game through most of that journey, slowing down to complete a few research missions and check in on a science lab in orbit around Kerbin’s second moon, Minmus. I use a mod called Kerbal Alarm Clock which is invaluable when running multiple missions at once. It does just what it sounds like it does. I can set alarms for various events like a ship is coming up on a sphere of influence change or a maneuver node. In this case I had an alarm set to remind me when the JE1 was getting close to Jool’s gravity well.

Tylo gravity breaking

Getting to your destination is only half of the challenge for interplanetary travel. You also have to slow down somehow to get into orbit. In the above picture the solid blue line shows the trajectory of the JE1 coming into the Jool system and then escaping. Not only that, but the ship would have picked up a little velocity because of how it was passing Jool. In previous versions of KSP, the easiest way to get into orbit of Jool was called aerobraking, and involved dipping into the upper layer of Jool’s atmosphere and using that to slow down. In the current version that just causes you ship to overheat and explode. Instead of using atmosphere, it’s possible to use gravity. Jool has three decent sized moons with nearly Kerbin levels of gravity, which makes them excellent candidates for this.

In the map screenshot above there’s a maneuver node at the top left of the blue orbit which creates the new dotted orange orbit. That orbit intersects with Jool’s third moon Tylo (which is highlighted in a peach color). Because the JE1 comes in on the backside of Tylo’s orbit, instead of picking up speed the craft instead sheds it, and after exiting Tylo’s gravity well the JE1 will be in the third green dotted orbit. This let’s me get the JE1 into an elliptical Jool orbit for only 73 m/s, compared to spending 250 or more burning on the periapsis marker of the blue orbit.

This kinds of stuff is very cool to me and one of the reasons why I enjoy KSP so much. Of course it’s fun to launch rockets, fly planes, and blow stuff up, but I have really enjoyed learning about orbital mechanics and getting a deeper appreciation for the science and work involved in space navigation.

Finally at Jool

Tylo Rendezvous ManeuversFinally in orbit of the Jool system, it was time to transfer to the moon Tylo and the initial moon landing. The Tylo rendezvous wasn’t difficult, but it was pretty tedious. First I had to push JE1’s periapsis out to intersect with Tylo’s orbit for 418 meters per second delta V which was about an 8 minutes and 30 second burn. Second, I needed to match inclination with Tylo, so we were orbiting at the same angle, which was another 192 m/s and 4 minutes. It’s not strictly necessary to match inclination but it makes rendezvous far easier to do and I’ve never had any luck without doing it. Lastly I needed to wait two orbits and then burn to bring down my apoapsis (point an orbit furthest from the center) to match Tylo’s orbit, which required 183 m/s and a 3 minutes 47 seconds burn. Again, time warp can’t be used while the ship is under acceleration, so I had about 16 minutes of real time waiting to sit through.

While it was really nice to have a design that included so much delta V, it hasn’t really been offset by a much lower TWR, which is why all of these maneuvers were taking so long. I’ll probably not be using this same design on my next big ship. Despite the slight frustration over waiting, I was finally in orbit around Tylo. The first really exciting part of the mission was about to begin.

KSP 2015-09-07 21-20-47-14

Jeb transferred over to the lander and undocked from the Jool Explorer. After making a save point, because nothing ever goes right the first time, Jeb made a small burn to bring his orbit down close to the planet above a landing site that  I selected semi-randomly. My only criteria was to get a different biome than an earlier probe mission so that I could run a full set of science experiments. After passing around the far side of the moon and making a second burn, I create a maneuver for the deorbit burn and waited as the Jool 5 Lander came back around to the daytime side of Tylo.

Tylo Deorbit

The deorbit burn was 1,495 meters per second, which was 67% of what I had in the descent stage. My plan had been to use that stage for most of the descent and jettison it just before landing. I had a minor moment of panic though because I wasn’t sure how much I would need before actually touching down. In the end I had almost a perfect amount. The remaining 33% was enough to keep my speed down for most of the descent after the deorbit burn finished. I ended up jettisoning the main descent stage and using about 460 m/s of my ascent stage touching down on the surface. But I had budgeted a few hundred extra meters per second on my ascent stage just for that reason. I thought it might be close, but I was pretty confident Jeb wouldn’t be stuck on the surface.

This Tylo landing was one of the more intense things I’ve done in KSP recently. It reminded me quite a bit of when I was first learning to do Mun landings and orbital docking. Trying to keep track of remaining fuel, heading, and descent velocity all while the surface is rushing up to meet you. These are some of the most exhilarating and rewarding activities I’ve ever done in gaming.

Jeb on Tylo

After planting a flag and running some experiments, I was a little anxious to get Jeb back into space and see if I could get him docked up with the JE1. Taking off from a moon with no atmosphere is pretty straight forward. You throttle up and point the craft to the east at a 45° pitch. East because then you get to add the rotational velocity of the body you’re on to your orbital velocity, and 45° is a good rule of thumb although you can always go lower or higher depending on the terrain.

It turned out that my fuel situation was a lot tighter than I realized. The Jool 5 Lander ended up in a 53.5 km by 17.5 km orbit with only 34 m/s fuel remaining. That’s not much, but this was after I had already gotten an intersect of 2.9 km with the Jool Explorer, so all I really needed was for my relative velocity to not be too much over 34 m/s when I got to my rendezvous point. I still have a bunch of monopropellant for RCS thrusters, but those aren’t create for slowing down more than 10 m/s or so.

Tylo with Jool, Vall, and Laythe

Tylo with Jool and it’s moons Vall (left) and Laythe (right)

After a last orbit of Tylo, Jeb’s Lander intercepted the Explorer and had a relative velocity of 45 m/s. Ideally it would have been 34 or less, but the remaining 11 m/s after I exhausted the lander’s fuel was easy to take care of with RCS. Docking went smoothly and then Jeb transferred back to the Explorer’s crew module bringing along all of the science he’d collected on the surface.

The next stage of the mission was to head to Laythe and land, but I ended up using more hydrogen than I expected getting from Kerbin to Tylo. So instead the crew of the JE1 will make for Bop which is where the orbital refinery that I had previously sent out is located. Bop is inclined and the fourth moon in the system, but it has very little gravity which made more sense for mining operations.