Minimum Delta-V to LKO

[PakledHostage]

This is a challenge that I enjoyed hosting years ago in the early days of KSP1 and I figured I'd dust it off now again because it's something we can do while we wait for the first round of bug fixes in KSP2:

Build the following rocket and launch it into a stable orbit around Krerbin (i.e. PE above 70 km) using the minimum delta-V possible.

The rocket contains:

MK1 Tin Can capsule
MK16 Chute
TD12 Decoupler between the tin can and fuel tanks
FL-T800 fuel tanks (qty 2)
LV-T45 Swivel engine

Launch the rocket into orbit and capture a screenshot showing the PE, AP and delta-V remaining. Don't forget to include the chute and decoupler in your build, because it makes a big difference to the delta-V remaining (and your kerbal's chances of getting home). Attempts must be hand-flown and cannot use MechJeb or other means of assistance and/or automation.

I will try and maintain a leader-board on here once a day.

Here's my entry  - 384 m/s remaining (it should be easy to beat because my AP is too high):

Note: You can get PE and AP to display at the same time by right clicking on them.

 

Leader-Board
===========

1. Bingmao (70.1 km x 70.2 km, 792 m/s remaining)

2. Lt_duckweed (70.3 km x 70.9 km, 781 m/s remaining)

3. AdamKSP (70.5 km x 71.9 km, 739 m/s remaining)

4. pakledhostage (71.2 km x 73.7 km, 710 m/s remaining)

5. speeding mullet (70.1 km x 81.4 km, 642 remaining)

6. draradech (70.2 km x 70.7 km, 527 m/s remaining)

7. Little 908 (70.0 km x 74.3 km, 431 m/s remaining)

8. klapaucius (79.0 km x 80.2 km, 402 m/s remaining)
 

Edited March 29, 2023 by PakledHostage
updated leader-board

[Draradech]

527 remaining, KSP2 0.1.0.0.20892 (for future reference)

Edited February 27, 2023 by Draradech

[PakledHostage]

Congratulations @Draradech! That's going to be pretty tough to beat! I will add you to the leader-board.

(Can you maybe film a video showing your technique? That's better than I've ever seen anyone do.)

Edit: I should add that there may yet be some room for improvement over Draradech's result. This challenge is a variation of the Goddard problem, so variation in thrust profile during the ascent may yield a few m/s improvement.

Edited February 27, 2023 by PakledHostage

[Draradech]

Sure. First, I'm not using the map screen for this, the indicators below the navball are sufficient.

Technique: Launch. Wait for 50 m/s. Start leaning over, keeping heading directly on the right border of the prograde marker until 45°. Stay at 45° until 10 km altitude. SAS to prograde, switch to orbit relative. Wait until AP is 2:00 in front, keep it there by throttling until AP is 70km, stop burn. At 0:15 to AP keep it close to 0:15 by throttling until orbit.

Got 496 in this video. I'm sure this can be improved, I didn't even try to optimize yet. (527 was my second try, this video is third)

 

[PakledHostage]

Awesome! Thank you. I will try that myself later. 

[Speeding Mullet]

642 remaining. First try and I wasn't being terribly efficient so I think it can be beaten pretty convincingly.  Technique was to launch full throttle, then start gravity turn, throttling down to about 66%, before throttling up to 100% at about 20 degrees.  Cut off engines about 71km, then circularise at full throttle SAS to prograde.

 

KSP 0.1.0.0.20892. Had fun, thanks!

SM

[PakledHostage]

Good job @Speeding Mullet! I will add you to the leader-board.

And to your point about more being possible, I tried about 10 times (revert to launch is one's friend on a challenge like this...) using a hybrid of your technique and @Draradech's technique and I was able to pull off orbit with 710 m/s remaining. I never would have thought it possible this time yesterday, but there's still room for improvement because my orbit was higher and more elliptical than it needed to be:

and

Edited February 28, 2023 by PakledHostage

[PakledHostage]

I suspect what's happening is that we're taking advantage of the LV-T45 "Swivel" engine's higher ISP at higher altitudes by lobbing it up, then coasting and then burning a second time to circularize.  And in light of how quickly the delta-V remaining numbers are going up, I expect that there's a bit of room yet for improvement...

[Klapaucius]

I only got 402, but I learned a lot doing this challenge. I love challenges like this. Does not take a lot of time, and I am a better player for having participated. I've played a lot of KSP1, but spent a lot more time with planes, so my rocketry skills are not what they should be. @Draradech: After a my first few pretty pathetic attempts, I decided to follow you advice, and I nearly doubled my Delta V!

[Lt_Duckweed]

771 m/s remaining in a 72.5km x 72.2km orbit.  Tilted over to 70 degrees above horizon by 110m/s then full throttle till apoapsis leaves the atmosphere, then circ at apo.

Next attempt, tilted over slightly faster, 70.9km x 70.3km orbit, 781m/s left

Edited February 28, 2023 by Lt_Duckweed

[PakledHostage]

Excellent. Thanks for submitting entries @Klapaucius and @Lt_Duckweed! I will update the leader-board.

Edit: I should add that I am really impressed by the precision of some of the flying that I am seeing in these entries. Especially @Draradech's  nailing 70.2 km x 70.7 km in a burn worthy of an IRL orbital insertion.

Edited February 28, 2023 by PakledHostage

[Speeding Mullet]

On 3/1/2023 at 7:14 AM, PakledHostage said:

Edit: I should add that I am really impressed by the precision of some of the flying that I am seeing in these entries.

Me too!  I can't even beat my first try any more, must have been beginner's luck!

SM

[AdamKSP]

Here's my attempt before I have to take a break.  I may try and get a bit better later on.  Thanks for the challenge!!

[PakledHostage]

On 3/22/2023 at 2:06 PM, AdamKSP said:

Here's my attempt before I have to take a break.  I may try and get a bit better later on.  Thanks for the challenge!!

Excellent. I will update the leader board.

[Little 908]

I kinda suck at this, but I at least managed to get 6th

 

https://imgur.com/a/YsjQf9E

do I get bonus points for landing back near the launch pad? lol

Edited March 25, 2023 by Little 908

[PakledHostage]

8 hours ago, Little 908 said:

do I get bonus points for landing back near the launch pad? lol

You win the internet. Congratulations.

[Bingmao]

I went straight up until I reached 50m/s
Then a sharp turn to 70°
As soon as the Prograde marker reached the Level Indicator, I set SAS to Prograde and keep on full throttle until AP was at 68km
20sec before reaching AP, I fired the engines Prograde and kept the AP ~20sec in front of me until the APwas >70km
circularize

Result
Orbit: 71.504 x 70.635 km, (room for improvement)
remaining deltaV: 785 m/s


EDIT:
Second try result:
Orbit: 70.209 x 70.135 km
remaining deltaV: 792 m/s

Edited March 28, 2023 by Bingmao

[PakledHostage]

And we have a new leader!