One Engine to Rule Them All!

[veio]

@metaphor, I assumed a voyager style planetary tour would be possible but I was too lazy to do it congrates that is most impressive

[jwenting]

yes, should be possible if you get very very lucky with the planetary alignment (sheesh, maybe those astrologers do have something going after all).

[Plur303]

Very impressive Metaphor! I will have to try that. I was just attempting to do a Duna landing.

Gallery of my submission:http://imgur.com/a/ivMM5

Kerbin orbit 1

Mun encounter 2

Kerbin escape 3

Duna encounter 6

Duna orbit 2

Total 14

Multipliers: 2X for Kerbal onboard and 2X for landing on Duna

14X4=56 points

Mun Encounter

Stable Kerbin Orbit after Mun encounter

Duna encounter and aerobrake

stable duna orbit after aerobrake and burn at apoapsis

Coming in for a landing on Duna

landed on Duna

Edited June 24, 2013 by Plur303

[adammada]

@metaphor - how, how did you managet to do it all? Did you use some external tool ? How you planned that? I want to do something similar, but dont know how, when, what order, etc.

[NeilC]

@metaphor - how, how did you managet to do it all? Did you use some external tool ? How you planned that? I want to do something similar, but dont know how, when, what order, etc.

Yeah, please share your method metaphor! I'm always impressed by your entries, and I don't know how I'd even get the maneuver node system to do the things you do with it.

I notice your mission took roughly 32 years. Does that represent a lot of travel time in transfer orbits, or a lot of waiting around for random encounter chances?

[zarakon]

metaphor is some kind of KSP wizard

[frash23]

metaphor is some kind of KSP wizard

No, he just knows his stuff.

[metaphor]

So gravity assists are not really that hard, just time-consuming.

First I went from low Kerbin orbit on a transfer orbit to Eve with a 1400 m/s burn. (Eve wasn't right at the minimum phase angle but that's OK because it gives your gravity assist more energy). So a day or so before I got to Eve I did a trajectory correction so that the Eve encounter would leave me in the right orbit. This correction doesn't take too much delta-v if you do it early enough.

Generally, you want to look at what direction your ship leaves a planet's SoI. (It is always going to leave at the same speed that it entered, so the direction is what matters.) If you leave in the same direction the planet goes around the Sun (planet's prograde), you will get a boost and be kicked into a higher Sun orbit. If you leave in the opposite direction (planet's retrograde), you will be slowed down and be kicked into a lower Sun orbit. If you leave north or south, you will be kicked into a higher inclination Sun orbit. If you use the blue and purple directions on a maneuver node early enough, you can change where your periapsis is with respect to the planet with very little fuel. And where your periapsis is determines in what direction you will leave the SoI.

After Eve I want to go to Duna. So I left Eve's SoI in the direction of Eve's prograde, getting an orbital boost. Now my Sun orbit had a periapsis at Eve's orbit and an apoapsis between Duna and Dres (something like this). I also changed my inclination so that either the ascending node or descending node of my new orbit was right at the intersection with Duna. This guarantees that the orbits will intersect, and also makes the game show the closest approach markers.

So now I have an intersection point with Duna's orbit, but Duna will be nowhere near it at the time that I pass there. So I had to wait a few orbits. I placed maneuver nodes one behind the other to show where the closest approach point would be after multiple orbits. When I found one that was close enough (in this case it happened after 4 orbits) I did a small burn at the first maneuver node so that I would intercept Duna after 4 orbits. Something like this. See this album for more on maneuver planning more than one orbit in advance.

At Duna I did the same thing. Duna is not as massive so it cannot bend your path like the bigger planets. So I used its gravity assist to put me on a path to Kerbin one orbit later (like this). Then I used Kerbin's more powerful gravity assist to get my apoapsis far enough out that I intercepted Jool (like this). Jool is so massive that it can bend your path in pretty much any direction you want. Jool put me on an intersection with Eeloo (like this). Eeloo can't bend your path that much so I had to burn some fuel there to get me back to an intersection with Jool. Then from Jool I went to Moho (like this) and Moho's small gravity assist was enough to get me to Dres after 4 orbits (like this). From there I was kinda stuck in a highly inclined orbit with almost no fuel, but my orbit intersected Jool's so I used a Jool assist, then a Moho assist, then another Jool assist to get back to Kerbin.

So yes in general you can save delta-v with gravity assists, but it usually takes some waiting time in transfer orbits unless the planets happen to line up. If you want to see a cool example of real-life gravity assists,

.

[NeilC]

See this album for more on maneuver planning more than one orbit in advance.

Thanks so much for explaining this technique! It was the missing link that made sense of your screenshots. Super useful, I had no idea you could plan multiple orbits out.

[frizzank]

Well that was fun!

One aerospike... 7 planets.

The adventures of the aerospike

This was my design, basic asparagus

In Kerbin orbit

At Eve

Duna

Eeloo

Jool

Moho

Dres

Back at Kerbin

Gravity assists are awesome for saving delta-v, but require a lot of time. The hardest part was fine-tuning burns with the overpowered engine.

As for points, I think it's like this:

1 - Kerbin orbit

3 - Kerbin escape

5 - Eve

6 - Moho

6 - Duna

7 - Jool

0 - Dres (?)

10 - Eeloo

x2 - kerbal inside

= 76

Returned to Kerbin alive, all the way to impact with the surface

I changed the points to include dres, +2. Same points as the other moons.

80 points, surprised you didn't get any of the moons in the jool system?

Edited June 24, 2013 by frizzank

[frash23]

-snip-

See this album for more on maneuver planning more than one orbit in advance.

-snip-

Thank you so much for sharing this tip! +rep

[metaphor]

No problem. This kind of orbital mechanics stuff is why I play KSP. I really like how it allows you to get a feel for difficult mathematical concepts.

I didn't bother with the moons since I just wanted to get to all the planets. But it's totally possible to fly past the moons too, if anyone else wants to try it. Could probably have landed safely on Kerbin too if I packed a parachute.

Edited June 25, 2013 by metaphor

[Munbeast]

I was lured by the multipliers.

Kerbin Orbit - 1

Mun - 2

Mimus - 4

Kerbin escape - 3

Kerbals in ship x 4

Safe return x 2

Total: 60 points

Javascript is disabled. View full album

[occar]

Am I correct in my assumption that the non-RCS upper limit for delta-v with a single aerospike seems to be somewhere around 7,000 m/s? I've been able to asparagus in to the mid-6900's with the first stage actually starting with a TWR of only .98.

[dahud]

Hmm... someone remind me to do this one when I'm not at work.

[tavert]

Am I correct in my assumption that the non-RCS upper limit for delta-v with a single aerospike seems to be somewhere around 7,000 m/s? I've been able to asparagus in to the mid-6900's with the first stage actually starting with a TWR of only .98.

With a pod, yeah just about. Metaphor had 7237, you can improve a tiny bit on that by using the small inline decouplers (a la Munbeast and others) instead of the radials. Using a seat (like Francesco's design, but adding more fuel for good measure) should get you a bit higher.

[occar]

With a pod, yeah just about. Metaphor had 7237, you can improve a tiny bit on that by using the small inline decouplers (a la Munbeast and others) instead of the radials. Using a seat (like Francesco's design, but adding more fuel for good measure) should get you a bit higher.

Sorry, yes, this was with the lightest 1 man pod. I should have specified.

[Francesco]

a Mun return unmanned probe should be possible, by pushing that design to its limit:

note the TWR of 1.26: you could add maybe another stage (or some smaller fuel tanks) to squeeze even more delta-v out of it.

with precise piloting, a Mun return trip should take 7-7.1 km/s, so it could be achievable.

crashing on Kerbin in the end, probably

[Munbeast]

One aerospike, unmanned - 8197 m/s deltaV - Initial TWR 0.96

Not really much further you can go than this. The side tanks get you out of the atmosphere and then the top two tanks have to be jettisoned with the ship backwards, not a big deal in space.

[Hooligan Labs]

Always good to see the Aerospike getting some love. I wish it was being used more in the real world.

[zarakon]

Looks like Munbeast had the same idea as me.. improve the staging by putting them 1-by-1 on top. I managed to get a manned Mun landing, but not quite a return trip yet. Of course that would still be worth diddly for points. I could probably beat metaphor's score with this design though, if I had the mad maneuver node skills

[Oxytropis]

http://youtu.be/K9sas_-9qRw

my 2nd attempt, the first actually went better, without the extra doughnut and ant tanks, but I wasn't recording.

1 for orbit
2 for mun
3 for escape
3 for kerbals chill-axing outside

I was hoping for minmus encounter and eve splat

[Nao]

Great work on the mission metaphor! I 'm surprised that you didn't go with Mun slingshot as it can give more than 400m/s Dv.

If it's one engine to rule them all, then it's definitely not the aerospike :P, personally i would nominate the LV-T30

Being a little tired with studying i did a small test and for the same design not only the LV-T30 carries more Dv than aerospike but takes less Dv to achieve orbit.

Using design with a lot of stages, similar to the ones present in the thread, aerospike had vacDv of 8142m/s and took 5020m/s to LKO and LV-T30 had vacDv of 8906m/s (at the same 0.96 launch TWR) and took 4975m/s to LKO (same MJ profile). Thats 615m/s Dv difference in orbit (16% more Dv than aerospike)

Oh and this is more like "PTW" post with a twist, as i don't want to argue or discredit anything. I'll try the challenge after my exams.

[numerobis]

Looks like Munbeast had the same idea as me.. improve the staging by putting them 1-by-1 on top. I managed to get a manned Mun landing, but not quite a return trip yet. Of course that would still be worth diddly for points. I could probably beat metaphor's score with this design though, if I had the mad maneuver node skills

I was trying to work out how to use a single decoupler for every stage. I could get the thing balanced for the first stage, just barely, but lost control just before starting the second stage. If it worked, you could reduce the dry mass on Munbeast's design by several decouplers this way.

Note that cube struts do not seem to be affected by exhaust gases. Cube strut doesn't care. Cube strut doesn't give a $@#.

[frizzank]

Great work on the mission metaphor! I 'm surprised that you didn't go with Mun slingshot as it can give more than 400m/s Dv.

If it's one engine to rule them all, then it's definitely not the aerospike :P, personally i would nominate the LV-T30

Being a little tired with studying i did a small test and for the same design not only the LV-T30 carries more Dv than aerospike but takes less Dv to achieve orbit.

Using design with a lot of stages, similar to the ones present in the thread, aerospike had vacDv of 8142m/s and took 5020m/s to LKO and LV-T30 had vacDv of 8906m/s (at the same 0.96 launch TWR) and took 4975m/s to LKO (same MJ profile). Thats 615m/s Dv difference in orbit (16% more Dv than aerospike)

Oh and this is more like "PTW" post with a twist, as i don't want to argue or discredit anything. I'll try the challenge after my exams.

It was sarcasm. One for the fact that I rarely use the aerospike, two that forced to use only a single engine, aerospike would not be the best choice. Also its suppose to be hard.