Most Energetic Kerbin Impact

[SunJumper]

This challenge is to get the heaviest craft you can muster to impact Kerbin as fast as you can get it. You will be scored on final impact energy, being half the mass times the velocity squared. Ek=0.5mv^2. Ek=0.5m(v^2). Please use this equation, as I have. As you will be impacting after re-entry, you must also minimise drag on the way down.

To be considered, you need only a pic at launch, a pic at burn-out showing your final mass, and a pic as close to impact as possible (tip: spam F1). You may use any part (though try not to do this with infiniglide). You may use the solar-retrograde method. Just smack Kerbin as hard as you can. You must also have entered space at some point, so no dropping 400 jumbo tanks from a crane.

Tip: Getting into an 80km orbit, and burning for an apoapsis of 81600km at midnight, and burning 4km/s of delta-v, will get you close to the KSC. Make of this what you will.

With that, my entry:

Launch

Final Burnout

Just before impact.

Leaderboard:

Istas - 145 GJ

Metaphor - 31.1 GJ

Ninety-Three - 28.0 GJ

Sunjumper - 13 GJ

I know you can do better.

Edited April 27, 2013 by SunJumper

[foamyesque]

Pretty sure the winner is gonna be a dude who hoists four hundred -64 tanks ten feet.

[SunJumper]

Pretty sure the winner is gonna be a dude who hoists four hundred -64 tanks ten feet.

Thanks, I've done a minor change to the rules.

[hyperformer]

Leaderboard:

Sunjumper - 0.5*2120*238.3^2 = 60.2 MJ

I know you can do better.

[SunJumper]

on your math

So I found that in your description it said half the mass times the velocity,squared, but that isn't represented in your equation above.

What it might look like if the equation follows the description [(0.5*2120)*238.3]^2

Please click here to prove yourself wrong.

[Ninety-Three]

Clearly I think differently than you, because I hadn't even been planning to leave the atmosphere, let alone get far from Kerbin. In light of the updated rules, I changed my plans slightly, but found they still worked fine. You seem to be maximizing speed. I assumed that the atmosphere would bleed my speed down to terminal regardless of how fast I came in, so I set out to maximize mass.

Yeah, it's pretty silly. For the first minute and a half (before the first stage was jettisoned), time was dilated by a factor of four or five due to lag. But it was worth it.

I burned straight up, and here I am taking a jaunt out of the atmosphere to satisfy the rules. I forgot to get them in shot, but I've got some RCS tanks and a million side-mounted thrusters that I used to get myself pointing down while in space.

I waited until I was fairly close to ground to start burning, figuring it'd just waste fuel to start sooner.

And here I am about to crash. The screenshot is further from ground than I'd have liked, so I'll deduct a bit from my fuel to account for the fact that it should have gotten a little lower.

Calculating the mass:

19 engines * 6 t/engines = 114 t

4*18+5 dry fuel tanks * 2 t/tank = 154 t

80000 liquid fuel and corresponding oxidizer * (1/90) t/fuel&oxidizer = 888.9 t

128 RV-105 RCS units * 0.05 t/RCS = 6.4 t

2546 monopropellant * (1/250) t/monopropellant = 10.2 t

4 large dry RCS fuel tanks * 0.4 t/tank = 1.6 t

Command Pod Mk 1 + SAS = 0.9 t

Total: 1176 t

Ek = 0.5*1,176,000*(218.3^2) = 28.02 GJ

Boom.

Edited April 22, 2013 by Ninety-Three
Formatting

[Commander Zoom]

The demonstrated capability of Kerbin's atmosphere to act as a Magic Speed Brake does complicate matters somewhat. May I politely suggest that you shift the venue to the Mun?

[shand]

The demonstrated capability of Kerbin's atmosphere to act as a Magic Speed Brake does complicate matters somewhat.

Pssst: thats part of the challange.

"a pic at burn-out showing your final mass" its implied you have to have no fuel before reentry. implied but not stated. not that i think it would change things much

[Ninety-Three]

Pssst: thats part of the challange.

"a pic at burn-out showing your final mass" its implied you have to have no fuel before reentry. implied but not stated. not that i think it would change things much

Take a look at my submission. You can't have a kiloton of dead weight without either a lot of fuel, or a supercomputer to handle the lag. Having fuel left over lets you do some pretty extreme things.

[metaphor]

Here's mine:

On the launchpad

Making a burn around sun periapsis

Close to Kerbin

After impact

E = 0.5*3550*1193.7^2 = 2.5 GJ

It had way too much drag and slowed down too much in Kerbin's atmosphere

If it had kept its 40km/s speed, it would have E = 0.5*3550*40000^2 = 2.84 TJ

[Jason Patterson]

Something that will help maximize your final velocity is trying to impact a mountaintop rather than at sea level. There aren't any truly enormous mountains on Kerbin, but even an extra kilometer or two of altitude will decrease drag significantly.

[metaphor]

Another try, different strat

On pad

In space

Hitting ground

Mainsails with a big white fuel tank attached have a TWR of about 18 when they're almost empty, so good for getting high speeds in the atmosphere. Could have expanded the same design to make it bigger, but the lag gets too high.

E = 0.5*336000*430^2 = 31.1 GJ

[Commander Zoom]

Yeah, this pretty much confirms what I thought - despite what the OP seems to think, you can't minimize drag (under the current, very simple model), you can only overcome it, with brute force.

[SunJumper]

Yeah, this pretty much confirms what I thought - despite what the OP seems to think, you can't minimize drag (under the current, very simple model), you can only overcome it, with brute force.

I'll try to find the least drag part and use that at high speed...

Edit: Found the part, it's the non-linear RCS thruster.

Edit: Atmo entry velocity was 6.8km/s, impact velocity was 6.2km/s. the atmosphere scrubbed off only 17% of the energy.

Making for an impact energy of:

0.5*50*6200*6200 = 961 MJ

By sticking the mk2 cockpit on the rocket I used above, I get an atmo entry vel of 4.7km/s, and an impact vel of 800m/s, for an energy loss of 97%.

And an impact energy of 320 MJ.

Maximising velocity can't hurt.

And, now I'm making the RCS thruster impact Kerbin from a Solar Retrograde Orbit (Eccentric, not circular). It impacted at 22.6km/s, for an energy of 13 GJ. Sure, that's half the energy of Metaphor's entry, but that's impressive for a single RCS block!

Edited April 23, 2013 by SunJumper

[Azivegu]

I remember coming in torwards kerbin from an apo way out from eeloo. It was quite a big craft. Kinda funny because i was planning on aero braking (calculated that i needed to go down to around 7,5 km just so you know how fast I was going) but wasnt paying attention until the Mün popped up to say hi. It didnt end so well. It must have impacted with severel GJ. Should try it out again sometime, was fun. Sadly Bob didnt agree, poor basterd.

[Istas]

On pad:

http://s78.photobucket.com/user/IstasPuma/media/onPad_zps606ad7b3.jpg.html

Final mass:

http://s78.photobucket.com/user/IstasPuma/media/finalMass_zps9d123f70.jpg.html

Impact velocity:

http://s78.photobucket.com/user/IstasPuma/media/impactV_zps349d786c.jpg.html

0.5*7000*(6431.4^2) = 144.77 GJ