Pds314

Duna and Back Speedrun

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Posted (edited)

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The goal of this challenge is to reach Duna, land, plant a flag, and return to Kerbin by the earliest possible ingame date.

Rules

1. No cheats outside the editor.

2. No mods that give an unfair advantage using parts or physics changes.

3. All Kerbals must return to Kerbin alive. Stranding them in space or killing them results in mission failure.

4. ISRU is fine, but obviously it takes time and mass. And can't produce Xenon.

5. Multiple launches is fine, but obviously it takes time to launch and assemble in orbit.

6. All dates are to be reported in Kerbin's internal date system. Not time since launch and not Earth days.

7. You are encouraged to use sandbox and start a new world.

8. No reactionless drives. If you wanna go to Duna using a Lander leg cannon-powered stock Orion drive or something I won't stop you, but no Kraken or fuel transfer or ladder drive Shenanigans.

9. Any Aesthetic, informational, autopilot, or fly-by-wire control mods are fine.

10. Abuse of Kerbal jetpacks is wholesome and good.

11. You must land with a Kerbal to plant the flag. Don't figure out some way to bombard Duna with a flag at low relativistic speeds or something.

12. No abusing negative numbers in the date by having it loop around. I WILL know.

13. Anything in Breaking Ground and Making History is allowed.

 

General advice:

As long as your rocket is capable of reaching Duna from a day 1 launch, waiting for a faster launch with equal Delta-V cost won't get you to Duna any sooner. However you do also need to consider how fast your Duna encounter is, how you'll slow down, and when you'll start returning to Kerbin, as an early burn will be costly. As will a late one. And of course how you'll slow down once you get there.

The Hohmann transfer window BACK to Kerbin as on day 155, but the efficient transfer windows for higher speeds are at later dates. You're still better off taking an inefficient transfer for your Delta-V ASAP if it'll work for the most part though.

I have no clue if diving at Kerbol and using the short physical distance and Oberth effect to your advantage is a good strategy. The same goes for gravity assists. My guess is not that helpful.

Records:

1. Year 1, day 278, Duna Racer 1 by Esmenard

2. Year 1, Day 288, 3:34:07 in the Duna Done Quick by Pds314

3. Year 1, day 340, 3:03, minimalist ion design (Duna Racer) by SuicidalInsanity

4. Year 3, day 350, DOMA by Dire (left on Y1, D249 so far from optimal)

X. Both ways Hohmann transfer (for reference only): Year 4, day 80, ~3:30.

5. Year 5, day 409 in an SSTO by Reinhardt Mk.1

 

Edited by Pds314

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Posted (edited)

My trial run of my equipment ended rather abruptly the moment I entered Duna's atmosphere.

It looks like aerobraking at Duna will require *severe* heat shielding. A single Mk3 heat shield apparently cannot come even close to withstanding a 8.5 km/s entry speed into Duna's atmosphere.
It also appears that the heat shields melt quite awhile before their ablator is out. Meaning that the ablator is mostly useless if the goal is to actually aerocapture.
TeDXazx.png
 

Edited by Pds314

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Posted (edited)

Using a LOT of heat shields turned sideways, I have managed to fly a test payload down to 23 km and back up. Problem is it doesn't generate enough drag at that level to slow down much. It exited the atmosphere at 8.1 km/s. A stable orbit is 1.35 or so. Going much further into the atmosphere is fatal BEFORE all the heat shields are burned because of heat from other sources.

I'm not gonna say it's totally impossible, but wow is it difficult to make something capable of surviving reentry on such a small body at this speed and angle. It's nothing like Jool aerocapture even for similar speeds because everything is compressed down to literally a few seconds. My guess is that an appropriate 8500 m/s large payload class Duna heat shield will be much larger than 3 or 4 km/s of nuclear rocket propellant needed to bring that entry speed down to something sane. Seeing as my current device requires 48 3.75m heat shields and still doesn't work for actual capture. In fact this big bulb of shielding doesn't even give it 1 km/s braking at altitudes I've tested. At the moment diving to a periapsis of 16.7 km or lower is definitely fatal.

WrvkP5Q.png

Edited by Pds314

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wellllllp might as well plug this video again, i could've shaved some time off if i didn't mess up the kerbin transfer window the first time but: Duna and back in 4 years and 408 days

 

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4 hours ago, Reinhart Mk.1 said:

wellllllp might as well plug this video again, i could've shaved some time off if i didn't mess up the kerbin transfer window the first time but: Duna and back in 4 years and 408 days

 

Whoa that's like worse than normal Hohmann transfer times. But hey at least you went to Duna, and in an SSTO no less.

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Just now, Pds314 said:

Whoa that's like worse than normal Hohmann transfer times

lol yeah i could've been fine if i would've transferred right after taking off but i thought for a kerbin return transfer kerbin had to be INFRONT of duna and yeahhhh that was not the case lol

4 minutes ago, Pds314 said:

Whoa that's like worse than normal Hohmann transfer times.

well it only took three minutes for that to irk me so by the end of the week i'll do a true speedrun :cool:

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Posted (edited)
11 minutes ago, Reinhart Mk.1 said:

lol yeah i could've been fine if i would've transferred right after taking off but i thought for a kerbin return transfer kerbin had to be INFRONT of duna and yeahhhh that was not the case lol

I might have to reduce the aggressiveness of my approach if I can't aerocapture at 8.5 km/s without an impractical amount of heat shielding, but currently my strategy involves pointing nearly straight at the sun from a day 1 launch, then doing a half hour nuclear burn, with a possible secondary boost burn at Kerbol periapsis (there is no Apoapsis, missing Duna = Goodbye Kerbol system), which is close to being a Moho intercept trajectory if not for the timing meaning Moho is slightly ahead of me.

 

The idea is to put me on Duna within the low-mid-100s Kerbal days.

Edited by Pds314

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2 minutes ago, Pds314 said:

I might have to reduce the aggressiveness of my approach if I can't aerocapture at 8.5 km/s without an impractical amount of heat shielding, but currently my strategy involves pointing nearly straight at the sun from a day 1 launch, then doing a half hour nuclear burn, with a possible secondary boost burn at Kerbol periapsis (there is no Apoapsis), which is close to being a Moho intercept trajectory if not for the timing meaning Moho is slightly ahead of me.

i am surprised i made it this far in the game being how dumb i am because i see stuff like this and am dumbfounded

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22 minutes ago, Pds314 said:

The idea is to put me on Duna within the low-mid-100s Kerbal days.

now you're talking my language

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Hey some of my debris from aerobraking at Duna slowed down enough to not be on a Kerbol escape trajectory....

And is instead on a Kerbol IMPACT trajectory.
e5CyMHa.png

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I wonder if maybe something of this sort of configuration might be sufficiently heat-resistant since it has no large exposed faces.

yMeBBzJ.png

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When you plot a burn in LKO and point radial in to save fuel... oh no we are too low...

0ht1tWV.png

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Posted (edited)

I have done a proof of concept run. I got back to Kerbin by day 301 despite flipping out on a much less toasty 3600 m/s reentry after thrust braking. However, I misjudged the final reentry altitude on Kerbin and went flying off into space at 4 kms.

Edited by Pds314

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Posted (edited)

Full run: Year 1, Day 288, 3:34:07
Warning: image-heavy spoiler

5 minutes into Year 1, Day 1, a rocket ignites on the pad.
odmuiBd.png
 

Spoiler

Nearly 1000 tonnes of rocket fly through the air, one passenger, Valentina, onboard.
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To prevent the boosters from colliding with the vehicle, I perform an aggressive roll:
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Our TWR is now less than 1, but we are coasting on the powerful boosters.
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Staging and immediately reducing gimbal authority so it doesn't rip the payload apart or destroy the fairing.
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Circularizing with a stage that initially has a TWR of 0.60.
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Plotting a 174-day course for Duna.
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Using the remaining 500 Delta-V in the second stage to begin our burn.
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Nuclear booster stage is activated mid-burn. It almost melts the fairing.
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Cutting across the atmosphere to get the most out of the burn.
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Already on Kerbin escape trajectory.
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First look at the payload for Duna.
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It's beautiful. In its own way.
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A million meters above Kerbin.
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We managed to follow our planned trajectory almost exactly.
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The nuclear transfer stage is still hot. As you can see we still have 3000 Delta-V in the tank.
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Adjusting our Ike encounter to give us a more reasonable Duna Periapsis within the atmosphere.
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We begin our deceleration burn just after passing by Ike.
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And witness a total Kerbolar eclipse by Ike.
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We are down to 3 km/s as we are about to enter the atmosphere.
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And proceed to flip out and tumble, desparately rolling to prevent any more damage than necessary from occuring and trying to get our shield facing prograde.
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Checking the logs for damage. All but one of our solar panels were incinerated and we only burned off about a kilometer per second from the chaotic aerobraking, not enough to capture.
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The one solar panel remaining is on the lander. I would normally drop the RCS and fins on the return module after an aerocapture but I'm gonna need them for now.
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The lander is massively overbuilt for Duna with around 3000 Delta-V. Some of that will need to be burned off to enter a stable orbit.
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Narrowly-dodging the heat shield we just dropped.
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I don't want to endanger the landing so I switch to the nuclear engine. This is slowing down our run but we have little choice.
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We go on a long elliptical orbit that costs us about 7 Kerbal days. I probably should have just circularized where I was but I was concerned over fuel.
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We circularize on Day 181.
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Splitting the lander off from the return stage. Val hops into the lander.
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1 km/s reentry on Duna isn't fast enough to cause any thermal or aero-structural problems.
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Opening chutes.
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About to land. Suicide burn in three...
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Our burn was not hard enough. The lander fell over after a small bounce.
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No matter, we can just retract our legs and we naturally roll upright.
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And deploy again and our lander is fine.
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Deploying the ladder and preparing to explore Duna.
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After a jetpack jump, Val is able to make an impressive flight on her parachute.
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She likes this world. She is way more mobile on her own here than any other world with an atmosphere, while retaining the safety and maneuverability of a parachute.
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Heading back to the lander.
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Almost there.
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Decided to overshoot. 95.5 m/s in the atmosphere? Yes please!
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Deploying parachute.
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ALMOST! Val was able to perform a 3.2 km glide off a parachute and a second jump using her remain 0.31 jetpack fuel.
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After a short walk back to the lander.
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About to leave. Val repacked both her own parachute and the lander parachutes. Just in case.
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Leaping to the air to rendezvous with the ride home.
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Ike is visible on the horizon.
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412 Delta-V will be needed to circularize and match planes with the return module. Since the return module is neither crewed nor automated, the lander will need to do all of the work for Rendezvous.
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Well, we didn't time our launch so we need to wait a couple orbits. Also it's now officially Day 182.
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After a few orbits, we are near enough to just point and burn. With 244 m/s to spare, we can be quite aggressive.
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After a quick 80 m/s charge at the return module, we are only 90 m away. Val jumps from the lander, as it's now useless to her and has no way to dock and transfer its remaining liquid fuel to the nuclear return module.
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Val lands on the return module, about to get back inside.
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And it's time to do our return burn. Charted out as a 3100 m/s burn. We have over 5 km/s of Delta-V though so it should be okay.
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The burn completes almost perfectly.
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With quite a bit of Delta-V left after some adjustments to our encounter, more actually than it claims in the UI. (For some reason it insists our starting mass is 11.3 tonnes and final is 9.5. In reality our current mass is about 7.45 tonnes and our final empty mass should be 5.65. Same difference in fuel, but the lighter actual empty weight means we actually have 2.17 km/s of Delta-V). In any case, we have around 2 km/s and we need to slow our reentry speed down as much as we can.
SK53De3.png

Aiming for a 25 km Perikee.
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Just finishing the deceleration burn.
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Staging off the nuclear return module.
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The reentry module gets hot as soon as it hits the atmosphere.
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Explosions from the liquid fuel tanks in the nuclear stage.
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The nuclear engine itself explodes less than 100 meters from the reentering capsule. Fortunately the 6000 m/s wind means Val is safe from the radioactive materials inside.
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Slowing down as the outer heat shield continues to ablate away.
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2150 m/s. Officially not in orbit anymore.
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Still moving supersonic but the reentry flames are gone. And it looks like the capsule was actually overbuilt, with the ablator not even 25% depleted.
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As we slow down below mach, semi-deploying the chutes.
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Chutes fully deploy with 7 G of force.
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The heat shields splash in the ocean below. It looks inviting.
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So inviting that Val climbs out of the slow-descending capsule.
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And dives for the water.
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Deploying her chute.
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And finally splashed down.
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Things that could be improved:

1. Heat shield on Duna needs to face correctly. Perhaps putting it on the side of the craft would work?
2. If the heatshield is faced correctly, then I don't need to slow to 3 km/s. Maybe 4-5 km/s would suffice.
3. That being the case, I can burn more aggressively and get to Duna up to maybe 20 days earlier.
4. I need to actually aerocapture at Duna. Not waste Delta-V trying to decelerate afterward.
5. And then immediately circularize. Not waste several days getting back to periapsis.
6. I can burn harder from Duna and get to Kerbin sooner, then reenter fast enough to actually need 2 heat shields.

All in all I think I can see at least 40 days of time improvement without making the rocket any bigger.

Edited by Pds314

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4 hours ago, Reinhart Mk.1 said:

;.;;.;;.;

I edited the leaderboard because I realized you got back on Year 5 since it starts counting at 1. It doesn't change your position though.

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11 hours ago, Pds314 said:

I edited the leaderboard because I realized you got back on Year 5 since it starts counting at 1. It doesn't change your position though.

oh it's all good! honestly just the fact that i built an SSTO that can make it to Duna and back is enough for me. this is really interesting though, this concept. honestly ive always thought about how nice it would be to conveniently go to mars but i always thought of how long the journey would be. a little over a year would DEFINITELY be doable if it was a civillian flight

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Initial attempt I got back on Year 1, day 340, 3:03 with a minimalist design using ions instead of nukes. Total rocket cost ~110k
jR2WIaO.png
Total mass of the Duna racer is just under 4 tons. The deliberately oversized lifter has ~1k dV spare after circularization, which is used to boost the racer out of Kerbin's immediate gravity well before firing the ions to the tune of ~3500dV for a ~174 day Duna intercept.
VRjCNRR.png
The Duna Racer has no heatshields as they are far too heavy, so another ~3k dV is spent decelerating prior to entering Duna orbit at Year 1, day 174, hour 3.
On an unrelated matter, Stock really needs a larger array style solar panel
wDe07ut.png

Val heads down to Duna on what is just about the most minimalist lander possible.
z4rs1gv.png

48 minutes later val sets foot on Duna and plants the flag.
ZGAZT8H.png
With extraneous weight ditched, the lander has about 2100-2200 dV left, just enough to get into orbit and intercept the Duna Racer. There isn't enough fuel to match orbits, so that is done via jetpack.
An hour 33 minutes after landing val makes it back the the Racer and begins the burn home. Propellant is beginning to get scarce, so a mere 2k dV is used for a 165 day Kerbin intercept.FH2snWw.png
The last ~1900 dV is spent decelerating as much as possible, so the Duna Racer slams into Kerbin's upper atmosphere at a mere ~3500m/s. Solar panels melt long before they have a change to be ripped apart by aero forces, followed by the engines soon after, but not before aerobraking slows the craft enough to be captured in an elliptical orbit around Kerbin. A day later the second aerobraking pass brings the craft suborbital.
DPVzHg7.png
This is fine.
obfXB3x.png
Original plan called for ejecting and using Val's parachute to land, but apparently Xenon tanks provide enough of a crumple zone for a survivable touchdown.
Round trip time: 340 days, 3 hours.
There's a lot of room for improvement with this design, but that mainly boils down to strapping on more Xenon tanks for extra dV, and commensurately longer ion burns - ion burns with the lightest ship I could make still took ~30-40min per burn, real time. Thank the Kraken for the BetterTimeWarp mod.

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I am currently beginning my speedrun, a 900 ton monstrosity with more than 14 km/s in Kerbin orbit. If everything goes well (spoiler : it won't), it should make Duna and back by Year 1 Day 267.

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I think I need to ask the obvious, but difficulty settings should be set to "normal", right? Because heat shielding on Duna is simple when you run in "easy" mode with 50% heating.

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Posted (edited)

Probably not going to win any records since I'm using Hohman transfers, but my DOMA challenge would probably qualify as an entry for this. Duna launch 1 left on Y1D249 and is expected back around Y3 D350 or so, for a total of 2 years 100 days or so. 

 

By "return to kerbin" do you mean "enter kerbin SOI" or "landed safely at KSC"? Because one of those is a lot more likely to result in a rapid unplanned disassembly.

Edited by dire

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Posted (edited)
On 7/22/2019 at 4:29 AM, Pds314 said:

Records:

1. Year 1, Day 288, 3:34:07 in the Duna Done Quick by Pds314

Is that the elapsed mission time? Or is it year 1, day 288 from the epoch? If so, I'm wondering how that would be possible. Returning from Duna after cheating it to orbit and landing on Kerbin took about 300 days alone. Is it actually possible to get to Duna and back in less than the time it took me to get back?

EDIT: Yup, somehow I missed the video slideshow of you showing how you did it. Ignore this whole thing.

Edited by doggonemess
Because I'm dumb. And because I type the wrong words sometimes.

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My entry on this challenge, Duna and back by Year 1, Day 278, using a monstrosity of 900 t on the pad, and 180 t in Kerbin orbit.

https://imgur.com/gallery/ZmI2R1q

Things that could be improved (if i ever want to do a second run) :

  • Knowing what is the most efficient trajectory with the delta-v I have (on this run I was mostly guessing the trajectories)
  • Knowing how to best perform long maneuvers in order to have as few losses as possible (again here I was mostly eyeballing, F5-ing and F9-ing)

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Posted (edited)
13 hours ago, esmenard said:

My entry on this challenge, Duna and back by Year 1, Day 278, using a monstrosity of 900 t on the pad, and 180 t in Kerbin orbit.

https://imgur.com/gallery/ZmI2R1q

Things that could be improved (if i ever want to do a second run) :

  • Knowing what is the most efficient trajectory with the delta-v I have (on this run I was mostly guessing the trajectories)
  • Knowing how to best perform long maneuvers in order to have as few losses as possible (again here I was mostly eyeballing, F5-ing and F9-ing)

Nice. That is uncannily similar to my design in staging and engine choice yet still very much its own thing. And beats my time despite being a few tonnes lighter too.

@SuicidalInsanity I love your lander design. And I'm impressed that anything as light as your launch vehicle reached Duna and back that quick.

Edited by Pds314

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On 8/3/2019 at 6:48 PM, dire said:

Probably not going to win any records since I'm using Hohman transfers, but my DOMA challenge would probably qualify as an entry for this. Duna launch 1 left on Y1D249 and is expected back around Y3 D350 or so, for a total of 2 years 100 days or so. 

 

By "return to kerbin" do you mean "enter kerbin SOI" or "landed safely at KSC"? Because one of those is a lot more likely to result in a rapid unplanned disassembly.

I mean land. If you return to SOI at say 15 km/s you'll just cook yourself or flyby and then have a nice long journey into the interstellar void to contemplate your life choices. Remember, no stranding or killing Kerbals.

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