Tutorial: Lagrange Point Graveyard Gold
May 26, 2017 5:59:33 GMT
qswitched, thorneel, and 4 more like this
Post by imallett on May 26, 2017 5:59:33 GMT
Hi,
Getting the gold on "Lagrange Point Graveyard" is hard—and I've gotten gold on 2/3 the missions (silver on the rest).
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Record Time
First, accomplishing the mission (even in record time to get the silver) is fairly straightforward. The easiest way I've found:
My not-very-optimized trajectory is 1M 17D and takes ~17.71 km/s Δv, which is adequate to demonstrate it's possible.
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Record Δv
This is more difficult. To my knowledge, I'm the first player to succeed (though one youtuber exploited a glitch, which doesn't count, obviously).
To handle this, we need to take advantage of the Oberth Effect. Basically, we want a big part of our burn to be as low in a gravity well as possible. Thus, we:
The trickiest part is adjusting the maneuvers. The timings must be pretty much exactly this, and you'll want to tweak e.g. the inclination to get the intercept as perfect as possible. I find the interface particularly tedious for this, mainly because editing the first maneuver node deletes the second, and because the prograde direction is for a circular orbit. IRL, we'd want the burn near Mercury to be prograde along the current direction, which will change over the course of the burn. The game does not seem to support this.
My solution approach might not be optimal (in particular, more waiting orbits might help), and I didn't tweak it lower than 11.63 km/s (I find random adjustment really tedious, as mentioned above—plus it's a job for a computer, honestly). The total says 12 km/s, but this is because 11.63 rounds up.
Without further ado, here's some diagrams of this trajectory.
From Mercury reference frame:
From gunship reference frame:
From Sun reference frame:
Mission accomplished!
---
Ian
Getting the gold on "Lagrange Point Graveyard" is hard—and I've gotten gold on 2/3 the missions (silver on the rest).
---
Record Time
First, accomplishing the mission (even in record time to get the silver) is fairly straightforward. The easiest way I've found:
- Set up a burn: radial out 5.08km/s
- You should now have a very good incercept.
- Set camera focus to the gunship and fix the inclination.
- Switch frame of reference to the gunship.
- Fiddle with the intercept to get it as precise as possible.
- Do the join. If the automatic join takes too long, set up another manuever and manually brake first.
My not-very-optimized trajectory is 1M 17D and takes ~17.71 km/s Δv, which is adequate to demonstrate it's possible.
---
Record Δv
This is more difficult. To my knowledge, I'm the first player to succeed (though one youtuber exploited a glitch, which doesn't count, obviously).
To handle this, we need to take advantage of the Oberth Effect. Basically, we want a big part of our burn to be as low in a gravity well as possible. Thus, we:
- Wait one orbit (turns out to be key for the timing).
- Waste 450 m/s slowing down. This puts us on a collision (yes; collision, not low-pass) with Mercury.
- Burn 4.30 km/s low over Mercury (not exactly at periapsis; a little before and after because burns are not impulsive; this fact prevents a collision from actually happening).
- Accomplish the rendezvous.
The trickiest part is adjusting the maneuvers. The timings must be pretty much exactly this, and you'll want to tweak e.g. the inclination to get the intercept as perfect as possible. I find the interface particularly tedious for this, mainly because editing the first maneuver node deletes the second, and because the prograde direction is for a circular orbit. IRL, we'd want the burn near Mercury to be prograde along the current direction, which will change over the course of the burn. The game does not seem to support this.
My solution approach might not be optimal (in particular, more waiting orbits might help), and I didn't tweak it lower than 11.63 km/s (I find random adjustment really tedious, as mentioned above—plus it's a job for a computer, honestly). The total says 12 km/s, but this is because 11.63 rounds up.
Without further ado, here's some diagrams of this trajectory.
From Mercury reference frame:
From gunship reference frame:
From Sun reference frame:
Mission accomplished!
---
Ian
