Saturday, June 22, 2013

One small step ...

Yey !

Kerbals on the Mun. And back again.

I've watched a few more videos, learned a few more things, observed what was happening (often with horror for the poor Kerbals), trusted to luck and crossed a few fingers and toes.

This is the latest rocket in the assembly hall, before a few modifications. Like those yellow fuel pipes moving from the top of the tanks and down to the bottom where they actually do Stuff. Lots more struts too to keep the thing from flying apart.

One mistake I'm making is to build too much into the rocket. The best designs (watching the Scott Manley videos) are very simple. The rocket above has lots of boosters and engines down low which will :

Make the rocket topple over on the launching platform
Unbalance it so it doesn't fly straight
Collide with each other
Flex hugely (which doesn't help with the collision thing)
Overaccelerate (it's possible)
Squish the rocket in the middle

All of the above are bad and tend to have hilarious disastrous results.

Anyway - after one incredibly nervous launch, where bits of the rocket were threatening to harpoon other bits of the rocket, it's up in orbit around the planet and I'm next sending my rocket the way of the Mun.

I have to say here, I'm very lazy and have been making extensive use of autopilot features. I'm pretty confident that I could fly the rockets myself but the autopilots make things so much more efficient. They provide in game calculators to give you that precise time to make manoeuvres. That's possible to do by eye but fails the "you're making this way too hard for yourself" test.

Games are supposed to be fun, not hard work. If I need to use a few autopilot or calculator mods to increase fun and decrease tedium, I'll use the cheaty mods.

Soapbox over ! More screenies !

Kerbals on the Mun :
I was just on the day side of the Mun, which let me get that great shot of the Kerbin home planet and their sun in the same view. I was down to just the lander and return home stage at this point, with less fuel than I wanted because the ascent stage hadn't done all that I needed it to.

And home time - I've cut here to where I'm thinking about setting up how to get my guys home :
I've left the Mun behind, with my capsule being the little grey icon in the middle. I'm heading towards the planet at this point with lots of time to go until I can do the next manouevre. Orbital mechanics have 2 important points : Periapsis and Apoapsis. Periapsis is the closest point of approach, Apoapsis is the farthest point. To change one, the most efficient way is to make the manoeuvre at the other.

Plan - drop into the atmosphere to burn off speed. To do this, I have to change that 194.2km periapsis down to below 70km (the edge of the atmosphere). And I have to do that with only 93m/s delta V left. Delta V is the way fuel remaining is measured - it takes into account :
Acceleration (as a Thrust divided by Mass thing)
Actual fuel remaining (time the thrust is available)
And tells you the amount of change of velocity you can do.

93m/s works out to 209mph. It's the same as being able to accelerate a car up to 35mph and stop it again, 3 times. I bet you've done that in traffic, it's not that much. (3 stops for the bus). At the mid point in the orbit, the ship was doing 350m/s, at periapsis it's doing around 3000m/s.

Scary. But the braking is still possible ... The screenie above shows me manually setting up a manoeuvre at apoapsis, which led to :
That's a move that skips the ship off the atmosphere and scrubs some speed off. The periapsis is dropped from 194km to 61km by just using 19m/s of delta V. After a few more orbits and braking using the atmosphere (and a reentry that would have been extremely toasty) :
Kerbals on the ground, home and safe.

Yey ! Dunno how much more I'll do with this game. I traditionally don't stay long with open sandbox games as I run out of objectives quickly. I will keep following the Scott Manley videos though.

Can't close this post without showing this one though :
Next time - I'll ignore the "3 points of contact = best" theory and put a few more legs on the lander.

PS - I'm watching the Le Mans 24 hours today. There was a crash at the start which I thought was fairly ok. Motorsport safety has improved so that injuries are rare and fatal crashes, at this level at least, are now unheard of. But not today. Thoughts are with the family of Allan Simonsen. Shocked to hear that a crash I thought he'd walk away from has actually taken him from us.

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