Kerbal Space Program: Let's Light This Candle

To be more accurate, my 3 Kerbals are space junk! I hope they appreciate how much their sacrifice has done to advance the state of Kerbal science.

Oh neat! Subbed for future space endeavors.

Also, if you want a handy orbital mechanics reference book, a solid paperweight and a good sleep-aid, I recommend Wertz's Spacecraft Attitude Determination and Control:

http://www.amazon.com/Spacecraft-Att...

Mixolyde wrote:

Also, if you want a handy orbital mechanics reference book, a solid paperweight and a good sleep-aid, I recommend Wertz's Spacecraft Attitude Determination and Control:

http://www.amazon.com/Spacecraft-Att...

Well... it's not brain surgery.

[size=1]couldn't resist[/size]

The capsule needs an oxygen meter. So guys stuck in a stable orbit die eventually. Also, I wish it'd have some situations that automatically end the flight, such as the guys all dying.

Rapidly approaching my second apogee. Doesn't seem to be a way to tell where the launch pad is as you pass over it, so I'll have to use apogee & perigee to count my number of orbits.

Edit: 2nd apogee at 1685km, min speed 826m/s.

My rocket design:
IMAGE(http://dl.dropbox.com/u/5977984/screenshot24.png)

First apogee:
IMAGE(http://dl.dropbox.com/u/5977984/screenshot18.png)

Somewhere near the perigee:
IMAGE(http://dl.dropbox.com/u/5977984/screenshot19.png)

Second apogee:
IMAGE(http://dl.dropbox.com/u/5977984/screenshot20.png)

That's when I called it.
IMAGE(http://dl.dropbox.com/u/5977984/screenshot23.png)

Seems that I lost just a bit of elevation on that second time around. Possibly indicates a slowly decaying orbit?

Heh, at least your guys look like they are having fun.

Mixolyde wrote:

Also, if you want a handy orbital mechanics reference book, a solid paperweight and a good sleep-aid, I recommend Wertz's Spacecraft Attitude Determination and Control:

http://www.amazon.com/Spacecraft-Att...

I recommend Introduction to Modern Astrophysics by Carroll and Ostlie. It's slightly cheaper. Also, since it's 1400 pages long, it makes a much better paperweight. Or monitor riser.

Got a really solid orbit set up tonight. It's a little elliptical, but not too bad. Ranges from right at 40,000 m at perigee, and about 42,500 m at apogee.

this game is addicting. and now that I've discovered usermade content: i can't stop. Haven't bothered with orbits just altitude so far. I thought 350,000 meters was good but now that I see you guys getting up even further I gotta keep pushing!

Since it's somewhat topical to the subject at hand, I'm going to through a link out for a friend's gravity simulator: Gravitation3D.

One good lesson from this game: getting into AN orbit, any orbit, isn't that difficult. Getting into a specific orbit, on the other hand, is hard.

You start to understand the old cliche about things that aren't difficult not being rocket science.

Oh, and Mixolyde, you've got an extra /quote tag at the end of your post. It's swallowed everything up and made it invisible.

Seems that I lost just a bit of elevation on that second time around. Possibly indicates a slowly decaying orbit?

Well if they're modeling the sun's gravity, it will be nearly impossible to get into a perfect stable orbit. Every satellite we have up there that's used for anything important has what they call "station-keeping" maneuvers, which are, generally, small thrusts to stabilize. The moon, the sun, the irregularities of the surface of the earth, EM radiation from the sun (real satellites have to compensate for the torque that photons from the sun place on their solar panels), and EM from the planet will perturb orbits slightly. Also, highly elliptical orbits if they're not at the right speed can shift around because of slingshot effects, atmospheric drag, surface of the planet, etc. Keeping a spacecraft locked into an orbit is not easy.

And, no, I'm not a rocket scientist, but I am designing software for a satellite ground system, so I've been teaching myself the basics of this stuff for the past year or so. I hope one day the Khan Academy starts doing astrophysics.

And, as a point of comparison, the current generation of NOAA weather satellites are expected to remain operational for close to 15 years on very little fuel. Those guys are pretty smart.

Malor wrote:

Oh, and Mixolyde, you've got an extra /quote tag at the end of your post. It's swallowed everything up and made it invisible.

Thanks, was wondering what was happening there.

Malor wrote:

One good lesson from this game: getting into AN orbit, any orbit, isn't that difficult. Getting into a specific orbit, on the other hand, is hard.

You start to understand the old cliche about things that aren't difficult not being rocket science.

And getting it there isn't nearly as hard as keeping it there.

I'm loving this Yesterday I got my guys in to a nice, circular 38km orbit, with under 200m between apogee and perigee, and with about a sixth of a liquid tank of fuel left, I had plenty of fuel to do a little retro burn, dip in to the atmostphere, and come down for a nice water landing.

Today I got a larger (mostly liquid-fuelled) rocket in to orbit, and once in orbit I still had nearly a full tank left, but I realised too late that I'd forgotten to add a parachute. For a laugh, I tried a powered descent, using fuel to slow my horizontal movement and then to slow to a hover just above the ground. It didn't go exactly to plan -- when the rocket touched the ground it exploded -- but my guys survived!

IMAGE(http://wootangent.net/~lsd/blah/ksp-soft-landing.jpg)

I'm not sure how it calculates survival sometimes. I've had a couple where I've landed on parachute and the capsule still exploded when it hit the ground.

I also had one where the capsule landed on a hill and rolled all the way down it. That one was actually pretty funny.

Lol this game is fun, made it to 1,087,581 before i started making another monstrosity.

Has anyone tried a slingshot orbit to see if that gets them further away from the planet faster than just straight up?

Well the first tricky part is getting into orbit with enough fuel to be able to fire at the right time. Should theoretically be possible. It's just fun to try and get gigantic rockets going as far as possible.

So my current objective has been to put a ship into a stable orbit, then return it to earth safely. This means a booster or liquid rocket remaining attached to the capsule while it's in orbit and it's been tough getting that. Anyway, here's my success (sort of) story.

This is SUPER ROCKET
IMAGE(http://farm7.static.flickr.com/6130/5982836099_539ed5f18f_z.jpg)

I got a very nice orbit ranging between 242km perigee and 121km apogee. It develops some wicked oscillations at the start, because all of those boosters fire immediately, including the liquid fuel jets at the bottom.
IMAGE(http://farm7.static.flickr.com/6006/5982835763_23eb9d96a2_z.jpg)

After hitting my second perigee, I pointed the rocket straight down and used up my remaining fuel, ejected the empty tank, and popped my chute.
IMAGE(http://farm7.static.flickr.com/6023/5983399470_15199b1035_z.jpg)

So, yeah. I can't explain why the happened. The chute was open, the pod was fine.

Quintin_Stone wrote:

So, yeah. I can't explain why the happened. The chute was open, the pod was fine.

From what I heard, there is a bug where you explode on contact with the dark side of the planet.

Tannhauser wrote:
Quintin_Stone wrote:

So, yeah. I can't explain why the happened. The chute was open, the pod was fine.

From what I heard, there is a bug where you explode on contact with the dark side of the planet.

Best. Bug. Ever.

Tannhauser wrote:
Quintin_Stone wrote:

So, yeah. I can't explain why the happened. The chute was open, the pod was fine.

From what I heard, there is a bug where you explode on contact with the dark side of the planet.

Okay, that explains some previous explosions too.

Also....
IMAGE(http://dl.dropbox.com/u/5977984/screenshot44.png)

Does that last one even fly, Quintin?

Quintin_Stone wrote:

After hitting my second perigee, I pointed the rocket straight down and used up my remaining fuel, ejected the empty tank, and popped my chute.

Actually, your most efficient use of fuel in this case is to point yourself opposite the direction you are traveling and fire that way. You'll cancel most of your angular velocity and drop a lot closer to straight down toward the planet. That way you'll still have some fuel when you get lower down in case you need it.

Think of orbiting like spinning a ball on the end of a spring, instead of a string. If you speed up your spin, the spring stretches and you move outward to compensate. If you slow down the spin, the spring will contract and pull you in. If you maintain the spin speed, eventually they stretch of the spring will balance out and you'll sort of naturally find the orbit for that speed. If you stop that speed completely, the spring will just pull you straight in.

The major difference being that gravity gets stronger the closer you are, and an elastic force gets weaker the closer you are, but aside from that they're similar forces.

And if that piqued your interest, try the Khan Academy videos on Physics. They're awesome!

Malor wrote:

Does that last one even fly, Quintin?

Yes, but gets nowhere near orbit. Not enough long-term thrust for its weight. I'd like to do it with liquid fuel, however I've found that putting a decoupler at the end of a liquid fuel nozzle results in a very weak connection that is likely to bend, damage the nozzle, or even snap right off. Very frustrating.

Mixolyde wrote:

Actually, your most efficient use of fuel in this case is to point yourself opposite the direction you are traveling and fire that way. You'll cancel most of your angular velocity and drop a lot closer to straight down toward the planet. That way you'll still have some fuel when you get lower down in case you need it.

Fair enough, but it got me down.

I've been having fun playing with the parts that someone linked upthread. They're carefully designed and seem very much in the same spirit as the originals.

My last rocket was a parachute/module/separator on top of one long liquid tank and a 'fission thruster' (which is silly, but it's basically low thrust, high fuel efficiency), stacked on top of a double BIG tank, a quad motor, and four of the new long solid rocket boosters on the side.

One warning: you can't spool those big quads up to full power when you first liftoff; when you first hit spacebar, if that engine is at full throttle, combined with the boost from the four solids, the link to the upper rocket will fail and the whole thing will explode. Start out at about 1/3 throttle, and spool it up after you've cleared the launch tower.

You absolutely for sure can hit escape velocity in that beast. The hardest part is holding it stable during initial boost. It gets pretty squirrely.

An interesting observation about orbital mechanics: your orbital speed (and needed velocity) increases the lower you are. So if you want to orbit faster, you need to get into a lower orbit, meaning you need to slow down. You slow down to speed up; you speed up to slow down.

(well, more accurately, you slow down at apogee to lower your perigee; at perigee you slow down even more to lower your apogee to the same height. Voila, you are orbiting faster than you were, after spending a bunch of energy to slow down. )

This looks like it could be fun if you get bored orbiting.