To Duna in less than 120 hours

[xendelaar]

I wanted to see if I could make a fast, yet safe trip to Duna.

A normal trip usually takes around 270 Kerbal days (which equals to 1620 human hours).
I aimed to decrease the transfer time under 120 hours.

For this mission, I waited ( using the extremely precise eyeball method ) until the distance between Kerbin and Duna was at a minimum and then flew in a straight line at my target.
Using a 750 tonnes ship, I burnt over 18km/s of fuel along the way. The entire burn took over 2 hours to complete. I used the better time warp mod to increase physics warp in order to keep what's left of my sanity, hehe. I eventually didn't use the last 2 km/s of remaining fuel because I didn't have enough ablator to keep Jeb cool during the harsh aerobraking on Duna.

The whole mission was far from perfectly planned, so I figure with some fine tuning and some extra delta v, it could be possible to reduce the transfer time even further.

 

I made a small clip of the mission for anybody who's interested [1:00]

 

 

 

 

[Blaarkies]

1 hour ago, xendelaar said:

A normal trip usually takes around 270 Kerbal days (which equals to 1620 human hours).
I aimed to decrease the transfer time under 120 hours.

You should post this as a challenge (if there isn't already one). It sounds fun, the least amount of MET time from launchpad until crashed into Duna surface (or something precise like that), and a few rules around what is banned and how scoring potentially works.

You'll be seeing 5-stage (or more) Nerv-only rockets doing this trip 

[xendelaar]

haha, I already googled my behind off trying to find a challenge like this on the forum! However, I  couldn't find anything similar! perhaps I didn't use the right words? 

Posting it as a challenge is a great idea! I'll try to post something later today.  

[Mikenike]

@xendelaar, with enough fuel and time, you can force a transfer that is faster than usual with any planet, the big question is do you have the guts to throw 10mil away in fuel costs. If the answer is yeah, then throw as much fuel as possible into HKO, and use it all to get there as fast as possible. Once out of an SOI, you can use the fuel to its maximum. Burn most of it, and use the rest to decelerate when around Duna. Optimimally, you packed enough shielding to aerobrake into the atmosphere in one pass, using the engines around to assist in slowing you down. After fuel ha been burned, ditch the engines, and land the pod with a set of small thrusters and parachutes. Only downside, you have no way of returning the intrepid crew home.

[xendelaar]

39 minutes ago, Mikenike said:

@xendelaar, with enough fuel and time, you can force a transfer that is faster than usual with any planet, the big question is do you have the guts to throw 10mil away in fuel costs. If the answer is yeah, then throw as much fuel as possible into HKO, and use it all to get there as fast as possible. Once out of an SOI, you can use the fuel to its maximum. Burn most of it, and use the rest to decelerate when around Duna. Optimimally, you packed enough shielding to aerobrake into the atmosphere in one pass, using the engines around to assist in slowing you down. After fuel ha been burned, ditch the engines, and land the pod with a set of small thrusters and parachutes. Only downside, you have no way of returning the intrepid crew home.

yeah, you're absolutely right!    

In my mission, I still had 2 km/s delta v left when I stopped the engines and coasted towards Duna. I could have spent 1 km/s on going faster, and 1 km/s for decelerating near Duna  to even decrease the transfer time even further. However, in this case, it wouldn't have given me any better significant transfer time..
For instance.. IF the transfer time would drop below 100 hours, I would have done the extra burn, because it's a nice number.. but in this case it wouldn't be something like 112 hours or so. so that's why I didn't do that.  To Duna in less that 112 hours doesn't sound that much better than To Duna in less than 120 hours.

I do believe there is a maximum velocity where heat shield brake down immediately on reentry. On kerbin, I think that's around 8 km/s? On Duna it's obviously much higher! In my experiment at 20km/s and an altitude of 5 km, the heat shield lasted a couple of seconds before braking down. So there is room for improvement if you use bigger or more heat shields! 

I did a similar thing in another video I posted where I did a "no time warp IVA only" mission to the Mun. It was 50% accelerating and 50% decelerating hehe.    (shamelessly reposting my video again...: )

 

1 hour ago, Blaarkies said:

You should post this as a challenge (if there isn't already one). It sounds fun, the least amount of MET time from launchpad until crashed into Duna surface (or something precise like that), and a few rules around what is banned and how scoring potentially works.

You'll be seeing 5-stage (or more) Nerv-only rockets doing this trip 

btw. you're currently keeping score with the latest Caveman challenge, am I right?! Kodus for keeping that epic challenge alive btw!  
Sorry... you're that crazy dude that finished the caveman challenge Diamond style (which is just insane!! haha).  

(If you like, you can still initiate the Duna express challenge yourself  (or whatever names comes to mind :) ) ? I'm not a very good at keeping up a leaderboard. (tried it twice and failed miserably) . If you don't feel like doing it.. I will try to post something tonight. Just let me know. )

Edited February 23, 2021 by xendelaar
Just realized that Blaarkies doesn't maintain the leaderboard of the caveman challenge but finished the challenge on diamond level :D