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  On 5/16/2017 at 3:47 AM, Cpt Kerbalkrunch said:

Just out of curiosity, after having been gone for so many centuries, did your Kerbals return home to find it had become a Planet of the @ManEatingApe s?

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That made me laugh out loud - I got some strange looks from people nearby!

  On 5/16/2017 at 6:19 AM, Physics Student said:

Talking about scoring, the record-system works better than I thought, I'm gonna introduce some ani-records as well.

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I love the idea of anti-records to inspire creativity. There's so many different great approaches in this thread.

I'm also pretty sure we can improve on the normal records too - a low mass mission < 30 tons should be doable. Also by using only 5219 m/s @jonny showed that an SSTBAB (Single Stage to Burbarry and Back) is within the realms of possibility for anyone crazy enough to try.

  On 5/16/2017 at 12:40 PM, jonny said:

one small suggestion, how you could cut the Mission time in half, (or just double it): go from Jool back to Eve. the gravity assist is very easy to set up, because Eve has a very short orbital period. Eve is capable to kick out your Ap to infinity, but your Pe will always stay below Eve.

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Thanks for the tip! Just to check you mean go K-E-K-K-J-E -> To infinity and beyond?

(I'm also following your gravity assist conversation with interest)

Edited by ManEatingApe
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  On 5/16/2017 at 6:16 PM, ManEatingApe said:

Thanks for the tip! Just to check you mean go K-E-K-K-J -> To infinity and beyond?

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nope, K-E-K-K-J-E -> To infinity. Okay, you don't want to go to Infinity, but you have the possibility. Which means you can set up the last Eve assist, however you like, to get a Ap which suits your need. The big advantage is the low Pe. (below Eve) that means you don't need a very high Ap to flip the Orbit.

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  On 5/16/2017 at 7:18 PM, Bubbadevlin said:

Dang this looks hard.. but also really fun, might do this challenge :wink:

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The level of difficulty isn't actually all that high.  A big, dumb rocket can do it (as I've shown), and a little, smart one can do it too if you're more careful with how you spend your fuel.  What difficulty there is in the challenge comes from figuring out exactly what mission profile you're going to aim for, then constructing a ship capable of pulling it off.

Of course, I've had about a dozen failures for each of the two successes that I've posted, and am still having more as I work for a third (and faster) one.  Take the Dwarf Fortress mental approach to it: "Losing is fun!"

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  On 5/16/2017 at 6:16 PM, ManEatingApe said:

I'm also pretty sure we can improve on the normal records too - a low mass mission < 30 tons should be doable.

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Considering the current launch mass record was a brute force mission, yes.

  On 5/16/2017 at 6:16 PM, ManEatingApe said:

Also by using only 5219 m/s @jonny showed that an SSTBAB (Single Stage to Burbarry and Back) is within the realms of possibility for anyone crazy enough to try.

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Dang it! I wanted to create a challenge that cannot be done with an SSTO! That was my initial goal with this whole thing. I have a feeling, the delta v record will last a while, it's pretty solid.

  On 5/16/2017 at 7:18 PM, Bubbadevlin said:

Dang this looks hard.. but also really fun, might do this challenge :wink:

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It's hard, yes but it's less effort than a Jool 5 or an Eve return mission. I made it on my 2nd try and I was pretty surprised when I realized it's gonna work out. Just pack a crapload of delta v into a rocket and off you go!

Edited by Physics Student
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  • 4 weeks later...
  On 6/16/2017 at 8:02 PM, Laie said:

Ahem. Is there a solution to atmospheric entry @20km/s?

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Either use RO-rated heatshields (and even those might need buffing), expend 15-17 km/sec of delta-V to bring your reentry velocity down, or use similar techniques as you used to get to Burbarry to flip your orbit again (i.e: gravitational assists, bi-elliptic transfers, etc).

It's all just part of the challenge: not only do you need to make incredible velocity changes on the way to Burbarry, you also need to make incredible velocity changes on the way back.

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I was very busy the last weeks. Working hard to get my dV requirement down. But unfortunately I was not patient enough. I ended up using 203 m/s more dV than last time (including 600 m/s EVA propellant). But I made major changes to my rocket. I got the cost down to 15,780 Founds and the mass down to 39.846 t.

10WzOft.png

The short Story:

LKO -> Eve -> 2x Kerbin -> Jool -> 2x Eve -> Jool -> Rerosolar -> 4x Eve -> Separation between "Chair on Engine" and capsule -> 7x Kerbin -> Burberry going EVA -> rendezvous between "Chair on Engine" and Burberry -> 5x Kerbin -> rendezvous between Burberry and capsule -> 3x Eve -> Jool -> Kerbin Aerobraking and splashdown

dV from LKO: 1326 m/s -> Separation between "Chair on Engine" and capsule ->  1324 m/s + 600 m/s EVA -> rendezvous between "Chair on Engine" and Burberry -> 1435 m/s -> rendezvous between Burberry and capsule -> 737 m/s -> splashdown

The Long Story:

  Reveal hidden contents

 

 

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  On 6/16/2017 at 8:02 PM, Laie said:

 

Ahem. Is there a solution to atmospheric entry @20km/s?

 

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This is absolutely impossible. The maximum velocity seems to be at around 8 km/s.

But reading through all th entries is quite fun, they're all awesome. You should do it.

 

@jonny wow, 2 new records, yet again you amaze me. 

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I'm posting this here, because it's a really nice Video. I'm a huge fan of The Gamer Alchemist.

However, I don't agree with the reentry at over 60 km/s. Is that possible in RSS?

I'll put him in the Category 2

 

Edited by Physics Student
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  On 6/24/2017 at 3:03 PM, Physics Student said:

I'm posting this here, because it's a really nice Video. I'm a huge fan of The Gamer Alchemist.

However, I don't agree with the reentry at over 60 km/s. Is that possible in RSS?

 

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Really cool video. I especially like the close flyby of Jupiter. However, I'm with you on the reentry. I don't know enough about RSS to say it can't be done, so I can just compare it to what I do know. On my first attempt to rescue Burbarry, I tried a direct return at 18km/s. I set Pe at 60km, figuring I'd go for the "dip a toe" method. At that altitude, Kerbin's atmosphere is so thin, I figured I'd be safe and, even though it wouldn't slow me down a whole lot, it would at least slow me down a bit. I was dead wrong. I don't think I even hit 65km. About 2 seconds after entry, my ship just completely exploded. I know he basically had nothing but a heat-shield and a Kerbal, but I'm not sure that's survivable. Still looked cool, though.

Edited by Cpt Kerbalkrunch
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  On 6/18/2017 at 5:48 AM, Physics Student said:

This is absolutely impossible. The maximum velocity seems to be at around 8 km/s.

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I seem to burn in flame whenever I go above ~5.5km/s.

I'm pretty sure I am doing-it-wrong (tm), but still, 8km/s looks rather high.
Has that ever been mathemetically calculated? Or tested practically in a challenge of some sort?

I'm very curious what's the ultimate velocity limit to survivable kerbin re-entry... I wonder what kind of shenigan craft could survive at 8km/s (or above!).
...an idea for a challenge maybe..?

 

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60 km per sec is quite steep. The Galileo probe hit Jupiter at a mere 48 km/sec, and would have liquefied any human onboard. From what I've gathered, ordinary LEO rated shields would have just exploded on contact, and I'm not sure any RO part would've sufficed, nevermind liquidating the Kerbal cargo.

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  On 6/27/2017 at 4:57 PM, wibou7 said:

I seem to burn in flame whenever I go above ~5.5km/s.

I'm pretty sure I am doing-it-wrong (tm), but still, 8km/s looks rather high.
Has that ever been mathemetically calculated? Or tested practically in a challenge of some sort?

I'm very curious what's the ultimate velocity limit to survivable kerbin re-entry... I wonder what kind of shenigan craft could survive at 8km/s (or above!).
...an idea for a challenge maybe..?

 

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If you check my mission report on page 1, my reentry was at just under 8km/s. I got the distinct impression that I would not have survived if I'd been going much faster. In fact, I didn't think I'd make it at all. Had to try 3 times. I set Pe at 45km and then 40km the first 2 times. Skipped through the atmosphere and kept going. And that was after burning the last of my fuel at 300km to slow down enough to survive. The last time I set Pe at 35km (which I was afraid was too steep), burned retrograde at 300km, and (somehow) survived. I play strictly vanilla stock, so this was all legit. I even still have the quicksaves from the game, as well. I believe (before slowing down a bit) that I was coming in a little over 8km/s. I could reload it tonight and see if I survive without the retro-burn before reentry. I'm dubious if I'll make it, but I'll give it a shot and let ya know.

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  On 6/27/2017 at 4:57 PM, wibou7 said:

I'm very curious what's the ultimate velocity limit to survivable kerbin re-entry... I wonder what kind of shenigan craft could survive at 8km/s (or above!).
...an idea for a challenge maybe..?

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I'm sure having seen Scott Manley doing such a thing in a live stream. I'm searching for the video but can't find it.

Sounds like a great challenge! Go ahead and start one before I do so!

  On 6/27/2017 at 4:57 PM, wibou7 said:

I seem to burn in flame whenever I go above ~5.5km/s.

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What reentry vessel are you using? It's not only atmospheric shock heating that kills you, parts can also be destroyed by heat transmission from the heatshield. Make sure the part directly attached to the heatshield has a high heat tolerance itself.

Edit: Also, don't use the inflatable heat shield. It hasn't got ablator on it wich makes it explode at more than 5 km/s.

Edited by Physics Student
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  On 5/10/2017 at 10:20 PM, jonny said:

Okay, do it Kerbal style!!

P4M9c3S.png

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well, that was not a reentry, as i left Kerbin SOI again. but i think that is pretty much the limit. I will see if I can find the save somewhere.

Edit:

I found the save should work with stock KSP1.2.2:
https://www.dropbox.com/s/w2nahhz1mww7f1t/quicksave %232.sfs?dl=0

Pe of 37Km seems to be the limit with the engine and everything attached and 36Km if you decouple the engine section prior to reentry.
I experience a Bug where the RCS thrusters don't explode if reenter with the engine section attached, but the certainly explode if I decouple. That actually means I was able to do my first Entry to the challenge because of this bug :huh:.

 

Edited by jonny
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  On 6/27/2017 at 6:43 PM, Physics Student said:

Also, don't use the inflatable heat shield. It hasn't got ablator on it wich makes it explode at more than 5 km/s.

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I think another reason the inflatable is no good in a situation like this is because of the huge area it takes up. Not sure what to call it. Area of exposure? I think that that, mass, and angle of approach all make a huge difference in whether or not you survive such a high-speed reentry. An inflatable in that situation would be the equivalent of a high-speed belly flop into a lake of lava. Sounds painful.

I'll reload that Retro Rescue save tonight. Instead of slowing down, I'll use the fuel I had left to speed up and see if I can make it. Should be interesting.

 

One more thought: I wonder if even an Mk1-2 could survive? With it's larger width and higher mass, I'm not sure.

Edited by Cpt Kerbalkrunch
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  On 6/27/2017 at 8:18 PM, Cpt Kerbalkrunch said:

 An inflatable in that situation would be the equivalent of a high-speed belly flop into a lake of lava.

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Nice metaphor and sound reasoning. 

Drag depends, among other things in exposed area, with means stronger forces acting in a big parts like the inflated heatshield. I'm not saying that heat will necessarily build up faster(there are other factor to be considered) but mechanical stress for sure will be stronger.

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