# The Kerbal Cup Challenge

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If you have enough fuel to deorbit, you should have enough to adjust yourself to stay close to the satellite.

I'm going to download the satellite tonight and see if I can modify my Kerbatta Quatro http://kerbalspaceprogram.com/forum/index.php?topic=1279.0 to carry it. That thing's got lots of extra power, so I should be able to do it IF I can get my orbits to stabilize.

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If you have enough fuel to deorbit, you should have enough to adjust yourself to stay close to the satellite.

I'm going to download the satellite tonight and see if I can modify my Kerbatta Quatro http://kerbalspaceprogram.com/forum/index.php?topic=1279.0 to carry it. That thing's got lots of extra power, so I should be able to do it IF I can get my orbits to stabilize.

You'd be surprised how heavy this sat is. I know I was.

*grumble* How circular is 'circular'?

The rules say +/= 250m of orbit, so I assume that means you can't fly above 15,250 or below 14,750

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The rules say +/= 250m of orbit, so I assume that means you can't fly above 15,250 or below 14,750

The frigging instruments aren't precise enough for that kind of control. =(

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*grumble* How circular is 'circular'?

150km + or - 250m

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I'm at this too... using this I got the following:

At 149750 m v_circ is 2169.97 m/s. If I set periapsis to 149750 m and apoapsis to 150250 m the speed for that orbit at 149750 m is 2170.33 m/s (the difference between the two is 0.36 m/s)

As the speed is displayed with only one decimal place and the decoupling will change the speed to some degree (depends how heavy the rest of the ship is at that point...) this might be harder than I initially thought...

You have to get to 149750 m with a speed close to but not (much) higher than 2169.97 m/s launch the sattelite and hope that gives it a speed not higher than 2170.33 m/s...

Plus... try not to crash into it after decoupling like I did :

I also found, the easiest way to carry the satellite is to place it atop the command capsule and land with engine power...

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Does the satellite have to be in that orbit by itself, or can it still have bits of spaceship attached to it? I was thinking of making it part of my third stage, then jettisoning the whole lump and use my 4th stage to take pictures and land.

If it has to be alone, I'll have to enter orbit with the 3rd stage, get it PERFECT, then eject that stage, eject the satellite, then maneuver around.

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Does the satellite have to be in that orbit by itself, or can it still have bits of spaceship attached to it? I was thinking of making it part of my third stage, then jettisoning the whole lump and use my 4th stage to take pictures and land.

If it has to be alone, I'll have to enter orbit with the 3rd stage, get it PERFECT, then eject that stage, eject the satellite, then maneuver around.

Yes, it needs to be free-floating in order to do its job.

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My first try, the orbit of my satellite is elliptical, +/-10km

A margin of error +/- 250m is allowed in the orbit.

No cheap plastic trophy for me

The satellite deployed in a circular 150km orbit

A second screenshot of the satellite 20 minutes later, showing it at same altitude

(Okay, itÂ´s 10km lower..)

A third screenshot of the satellite 40 minutes after the first (which will be a bit more than one orbit,) showing it at same altitude.

A screenshot of the capsule safely landed.

I hate the dark side of Kerbin...

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How do you get it to launch off of the pod? I attached the satellite to the top of the pod but it won't release it.

edit: good job

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How do you get it to launch off of the pod? I attached the satellite to the top of the pod but it won't release it.

edit: good job

Change the sequence?

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Okay, I know I am too late to get the trophy (DAMN!) but I thought I'd give it a go just for the sake of saying I did it.

I created a variation on the successful Delta IV design (I forget who I stole that off! ), which consisted of a core stage and six radial boosters.

Originally the core was 4 LFTs and a LFE, with a decoupler to my standard Command/Service Module (which is the pod, a decoupler, an SAS and a single LFT plus LFE). With the satellite, I had to delete two LFTs. The way I envisage it, the core is now no more than an orbital maneuvering system; the boosters are meant to get the thing up to orbital altitude. The Command/Service Module is itself cut down, with only one tank; given the orbital altitude involved I am assuming that one tank will be needed to bring the capsule home, so there's not going to be a whole lot of margin for error.

As for the boosters, originally they were an SRB (structural only, because the LFTs don't connect to a radial decoupler) and 3LFTs, with the engine below and an SAS above. In this modified version, they will be doing the lion's share of the pushing to orbital altitude; they need more propellant, so I have stretched them to 4 LFTs. They have also been fitted with parachutes, simply because it is aesthetically pleasing to me to return such a large piece of hardware for re-use.

Unfortunately, the combination of extra fuel and the fact that the core stage no longer fires on take off caused a problem - namely, it didn't get off the ground.

My first attempt to solve the problem was simply to strap on an SRB on each booster. That solved the thrust problem off the pad, but when they burned out I was left without enough thrust at relatively low altitude.

I eventually solved that problem by adding three fuel tanks (again, turning the SRB into a structural unit), an engine, a SAS module and a parachute, and turning these strap on units into full-scale boosters of their own.

Well, this takes off just fine. But we've encountered a new problem - the radial decoupler hasn't the structural rigidity to handle such an unwieldy booster. So you have a torsional force that starts off badly and gets worse as you reach altitude.

About the best thing I can say for this design is that when problems strike we're usually high enough to rescue the crew. One test even had the crew shoot uncontrollably off into space (thankfully we gave the Kerbonauts a can of coke each and a packet of twisties, so they'll be right). Unless someone has some inspiration, I guess this challenge will have to wait until .9.0 - maybe the bracing to be released then might get rid of some of this twisting.

If any engineers would like to have a look at my rocket and offer some suggestions, I'm open to them! (attached)

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150km + or - 250m

I hate you, you know that? The rest of this is pretty easy but hitting that burn just right is... aaarrgh.

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Change the sequence?

I did, and I don't know what I'm doing wrong. I set it up so that the engine would be my final stage, and my second to last stage would be releasing the satellite. But it doesn't work and gggggaaaaaahhhhhhhhh

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Looks like the de-coupling rings give quite an impulse, which will ruin the carefully calibrated orbit if the decoupling ring is engaged while facing either prograde or retrograde directions (or either end of lateral axis).

So, when you've calibrated your orbit, turn 90 degrees left or right relative to prograde direction, and then engage the decoupling rings. This should minimize the effect of impulse on your satellite's orbit altitude, but will slightly change the orbital plane - which was not specified to begin with, so no loss there.

I did get on a pretty good orbit with my Behemoth design modified to accommodate the commsat, but the firing of decoupling rings messed up the orbit good and proper...

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Johno, the deadline is August 3 8:01pm EDT (or, August 4, 00:01 UDT) You have plenty of time!

Yeah, the orbital paramenters seem to be a little tight. I think we will just declare the closest person the winner for this round, and have the second Kerbal Cup challenge after 0.9 comes out. With the new parts and staging methods, it should be a lot easier.

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my attempt within 3km of the challenge

releasing satellite

20 mins

40 mins

landed safely

and pretty close to the launch site

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I got one that was 149.5-150km, incidentally, but gave up on it 'cause it didn't have the required circularity and started mucking about playing flightsim in space.

It turns out this is not the best way to re-rendezvous with your satellite module, so killed without trying the landing. However, now I'm on vacation. Time to get this done... tomorrow.

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Update:

I have now developed a booster that will do the job fairly nicely.

Ladies and gentlemen, may I present . . .

The Satelliteer 3B!

It has the thrust and the stability to hoist that bad boy up to wherever it's needed, and it's fully vanilla. In the most recent test, we have found no difficulty in reaching a 300km elliptical orbit. Now only my piloting skill stands between me and a serious contention for the Cheap Plastic Trophy!

Update to update: Owing to dreadful piloting, the test orbit reached a perikee of about 530km. Still it's a good ship.

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Update:

Ladies and gentlemen, may I present . . .

The Satelliteer 3B!

Looks like my latest rebuild. I'm on rev.4, and this has been the best thus far.

Successfully orbiting w/ sat in tow at 150k, but need to work on dumping the sat. It goes way out of position on decoupling. :'(

UPDATE: Got the satellite to 150.7km orbit. +/- 400m one complete orbit. Then I blew my last stage by accident and went spewing off in to nowhere :/ Looks like I'll be replaying this launch tomorrow. Launch was completed with rev.5 Stork (spoiler below).

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Looks like you've deleted everything you can from the original stork to get that tin can into orbit. well done, mate.

I ended up going the opposite route - more power. Instead of the three booster stacks you have, I added six. Also, you deleted your orbital insertion stage, relying on the core stage to get you into orbit. I kept that ring of decouplers.

The advantage of your version is structural strength - mine flaps around like a bird with broken wings. On the other hand, once it's actually at orbital altitude, its a different story - I jettison all but the last stage, and we have a really effective OMS.

Dammit, you were one spacebar in the wrong place away from winning this challenge! All the best for your next attempt. Looks like I get a launch window before you do . . wish me luck!

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Looks like you've deleted everything you can from the original stork to get that tin can into orbit. well done, mate.

I ended up going the opposite route - more power. Instead of the three booster stacks you have, I added six. Also, you deleted your orbital insertion stage, relying on the core stage to get you into orbit. I kept that ring of decouplers.

The advantage of your version is structural strength - mine flaps around like a bird with broken wings. On the other hand, once it's actually at orbital altitude, its a different story - I jettison all but the last stage, and we have a really effective OMS.

Dammit, you were one spacebar in the wrong place away from winning this challenge! All the best for your next attempt. Looks like I get a launch window before you do . . wish me luck!

I was too far off orbit anyways. (only +/- 250m :-X). Good luck on your launch, I will try to best my previous tomorrow. zZZzz time...

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Currently at target orbit. Circularising.

EDIT:

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARGH!

I was well into the process of circularising my orbit - after about an hour of work - when I accidentally pressed the spacebar - the same mistake as you made, exaraxe!!!!!

Not even as close to orbit as you were. Damn.

Ah well, the good news is that we deployed the satellite anyway, and the crew are safely returning home to the Keverglades as I write.

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I have just discovered: Fraps doesn't seem to be able to make screenshots when windowed

Needless to say, I had it... Believe me or not, apokee was 150121, perikee 149780. Disconnected Sattelite with 90Â° angle to minimize speed change (at perikee to minimize plane change), followed it 40 minutes, landed at the KSC because I was afraid of random craft exploding... Powered Landing off course because sattelite had been on top of the capsule... Even the thruster stayed on. It was brillant. Complete Mission Time was about 3:30 h...

But... no pic, didn't happen! ah well...

It's as they say... after the mission is before the mission.

This is my craft if anyone is intrested... It launches almost anything everywhere... exept maybe that silly moon thing...

The second stage is a little overkill... I probably could do with 2 tanks and put the sattelite between that stage and the last stage, use that to deorbit and land with a parachute (in this config first stage brings me into orbit somewhere between 60 and 100k, from there I transfer, takes about two tanks of stage two, the third is for deorbit.)

Edit: I just found out F1 does screenshots native... I feel stupid now.

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I have just discovered: Fraps doesn't seem to be able to make screenshots when windowed

.....

Edit: I just found out F1 does screenshots native... I feel stupid now.

Johno and I know how you feel. I've ruined 2 really close attempts by hitting the wrong button for shutting the damn engine off.

I made another run this morning [rocket flight characteristics] -->

Unfortunately I waited too long before cutting engines. Ran out of fuel in maneuvering before being able to circularize orbit. (+/- 400m variance) Try again later today. :hailprobe:

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Gentlemen, your achievements have been astounding. I have no doubt that this contest will come down to the wire, with multiple qualifying entries by the deadline three days from now.

I'm going to start the permanent Kerbal Cup Challenge category today on KNN to document your efforts. All Youtube videos will link back to the original author's page. A proud Kerbal nation salutes you! :hailprobe:

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