Launch Efficiency Exercise [Updated for 0.21.1]

[Guest doughbred]

Trying a couple new things today. At least one was successful. My first challenge! I hope I did it correctly. 6.75 units left.

Click for embiggening.

Well, I can tell you're better than me.

[PakledHostage]

Had another go at it this evening. Here are the screenshots:

[Quintic]

I did it once with around 5 fuel left, but I've been testing different ascents. I fail to get into orbit more often than not. Any basic tips for a new player?

Edited July 7, 2013 by Quintic

[honolululu]

Thanks Tarmenius and doughbred. So my first attempt and current entry was my best by far, and I even lost track of trajectory for moment and headed way off to like 85 degrees. I was real easy on the throttle. Can't remember where I read this, but it's like I want the thousands of m of altitude to be in the tens place of my velocity. So 1000m = 110 m/s

2000m = 120 m/s

3000m = 130 m/s.

At about 7000 m, I usually just go 100% to try and match 10000 m = 300 m/s. By about 35,000 m you should be heading for the horizon, looking at your Ap in map view, and shut off the engines just above desired Ap. It's a general plan that has its faults I'm sure. Works well for me usually.

I've tried two more manual ascents and scored 2.8 and then a 3.8. I scored around just 1 with MechJeb.

In other words, I just got lucky.

Edited July 7, 2013 by honolululu

[Quintic]

Here is my best attempt.

[tavert]

Also, metaphor, from my experience lurking these challenges it's usually either you or tavert who defines what's possible around here. If you think double digits is possible, put your money where your mouth is.

w00t, internet famous! 2 hours of tuning MechJeb gives me first in double digits:

The acceleration limit was enabled for everything except the circularization burn. Throttling down is key, but I'm not sure if constant acceleration is absolutely optimal.

[honolululu]

Nice tavert!

Tried some quick turns and didn't even make it to orbit a couple of times. Then I went back to a more traditional curve.

8.62 Map and fuel.

Craft view

Was going to say about how I really throttled down at around 44 km and tried to ride it out to 74 km. Like people are always hating on the Mainsails because they are too powerful and you have to throttle down. Well as you burn through that fuel, the TWR must get pretty high. Seems like the boss agrees.

The dang throttle wouldn't shut off though!

EDIT. Heh, I took what b]tavert posted and said let's apply that acceleration max, and use mechjeb, swith a few numbers to try and match my last "shoot mostly straight up, then have a quick smooth curve finish at 50 km attempt. And got 8.63. EDIT 2 Saw that's what he did better so tweaked/copied a couple more numbers for another MechJeb run. 8.90 We can keep these off the leaderboard.

Edited July 7, 2013 by honolululu

[tavert]

Little further optimized, ran at 22.5 m/s^2 acceleration limit up to 40 km altitude, then 12.5 m/s^2 limit until exiting the atmosphere.

[AndreyATGB]

MechJeb for info, tried a few times without it but going to map every 5 seconds kept screwing me up. I'll keep trying.

EDIT: Another circularization later, now I've got 1.91 liquid fuel and 2.33 oxidizer.

EDIT2: Here's my best manual attempt.

Edited July 7, 2013 by AndreyATGB

[NeilC]

Thanks for weighing in, tavert! I knew we could count on you.

I don't know if your scores should count, though... your apo is below 75km on both of them. As I read the rules, qualifying entries must have apo >= 75, peri >= 74. What do you think, Tarmenius?

I think we're on the right track with a long, low-accel coast above 40km. I duplicated your profile but with an apo of 75 and improved a bit on my previous score: 7.71 fuel remaining!

I didn't think your 74.5 apo would matter until I compared our delta-V expended: you used 2 less and that's the difference between 10.3 fuel remaining and 7.7. TWO M/S DELTA V! That's the level we're optimizing at, here. if Jeb sneezes during ascent, our score is buggered.

Edit: I just realized your flight was piloted by Jeb and mine by Al. That probably explains the 2 m/s difference right there.

Edited July 7, 2013 by NeilC

[PakledHostage]

I don't know if your scores should count, though... your apo is below 75km on both of them. As I read the rules, qualifying entries must have apo >= 75, peri >= 74.

That's not how I interpret it. Maybe it does need clarification? Tarmenius' post reads:

Here we will take an incredibly simple design and aim to put it in a nice 75km x 75km orbit, with a Periapsis no lower than 74km. Note that having an Apoapsis greater than 75km is perfectly acceptable, but will obviously result in more fuel being spent and therefore a lower score.

To me that says you only need a Pe above 74 km. It says nothing about minimum Ap. All it says is that you may have an Ap greater than 75 km. Obviously Ap must be greater than Pe which, as previously stated, must be greater than 74 km. It doesn't say it is mandatory to have an Ap greater than 75 km, however.

[Tarmenius]

Wow, quite the bit of activity while I slept!

On the subject of tavert's entries: The rules did not state that Ap needed to be greater that 75km, so his scores are valid.

Since we're dealing with such minute differences in fuel spent, and to allow everyone the opportunity to increase their score, I will change the target orbit to a 74km x 74km minimum. Originally, the 74km minimum Pe was in place to allow for some margin of error in piloting, but I must say I'm impressed at the precision of everyone's entries (even the manually piloted ones!). Does this sound fair to everyone?

And Congratulations to the new participants for completing this challenge!

[NeilC]

<...>I will change the target orbit to a 74km x 74km minimum. <...>

Cool, that was the line that threw me off. My mistake in interpretation, apologies tavert.

[Tarmenius]

I wouldn't consider it a mistake in interpretation. Since I didn't define the parameters with enough specificity, both ways of looking at it fell within the rules.

[Giggleplex777]

Here's my very bad first try:

I wasn't used to the high TWR of the rocket while doing my gravity turn and ended up getting a very crappy launch trajectory.

^Look at how bad that is.

Anyways, 3.58 Units of fuel left.

Vanilla KSP.

[Tarmenius]

That trajectory isn't too bad. After all, you did get the rocket into orbit. Congrats!

Actually, that pretty much looks like the ones I end up with. Hmm...

[Giggleplex777]

That trajectory isn't too bad. After all, you did get the rocket into orbit. Congrats!

Actually, that pretty much looks like the ones I end up with. Hmm...

I shall try again! And this time I'll remember to throttle down during the gravity turn.

[Giggleplex777]

Now that's more, like it!

7.78 units. Meh, could have done better.

This is when I do a proper gravity turn. I also misspelled the named at first.

I think there should be a mod-less leaderboard.

Edited July 8, 2013 by Giggleplex777

[Tarmenius]

Nice improvement! That moved you up a few places into 5th!

I understand the urge to separate auto-pilot users from manual pilots. I will admit that at times, I feel it can provide an unfair advantage. However, in this case, I don't think it does. To take tavert's entry as an example, he spent 2 hours getting MechJeb's settings to be just right. That requires him to know just as much about the ideal ascent profile as anyone else. This challenge, at it's core, is less about the act of piloting, and more about knowing what an efficient launch profile looks like.

metaphor's entry is close on tavert's heels, and he flew the rocket manually. I think this demonstrates that a skilled pilot can be just as good as MechJeb.

[mcirish3]

I thought I would offer an update on my progress since I do not have a video to post as of yet. I realized that I could find mech jeb's optimal trajectory for this particular rocket if I ran a few hundred test flight and recorded the data and plotted using Excel and Maple. That said I also realized that in actuality even with hundreds of test flight I was only going to get close the the Ideal trajectories. since I am still keeping the number of variable to 3, more on those in a bit. In reality there of many variable not the least of which many are derivatives including da/dt and dm/dt respectively. Where a=acceleration, and m=mass thus dT/dt=change in acceleration with respect to time and dm/dt=change in mass with respect to time. There are also many other variable, including d(u)/dh=change in resistive force with respect to height, and once you throw in a more complex rocket with multiple stages,you really start feeling overwhelmed. I am absolutely certain that their is a overarching function that could be made that would calculate the exact ideal path no matter the rocket, I also know for a staged rocket it would have to involve the step function. More on that here. But frankly I am at a loss as to how to proceed further in finding an idea function. (if it could be found mechjeb could be made to launch along a path Ideal for any rocket instead of some meen best path.)

All that said, the three variable I am allowing to change are curve % Curve end altitude and curve start altitude.( it should be noted that da/dt and dm/dt also change but at the same rate i.e. max rate this rocket allows) I will hopefully find an optimal curve by the end of the week (no sooner I fear) and it will only be good for this rocket. But since I find this fun I hope I won't tire of it before I am done with my tests.

Edited July 8, 2013 by mcirish3

[Giggleplex777]

Nice improvement! That moved you up a few places into 5th!

I understand the urge to separate auto-pilot users from manual pilots. I will admit that at times, I feel it can provide an unfair advantage. However, in this case, I don't think it does. To take tavert's entry as an example, he spent 2 hours getting MechJeb's settings to be just right. That requires him to know just as much about the ideal ascent profile as anyone else. This challenge, at it's core, is less about the act of piloting, and more about knowing what an efficient launch profile looks like.

metaphor's entry is close on tavert's heels, and he flew the rocket manually. I think this demonstrates that a skilled pilot can be just as good as MechJeb.

metaphor did his with info from MechJeb. In my opinion (and it's only my opinion) I think zarakon's entry was probably the best.

[Nurph]

My best so far:

[Danger Will Kerbinson!]

Taking my first crack at a challenge.

Manual control, using Kerbal Engineer Redux to watch the orbit but no Jeb. Pretty sure I can crack 10 on manual since my AP ended up wasting fuel being higher than needed.

[metaphor]

Got one up in double digits without using MechJeb at all. Even made a video! It's pretty boring.

I guess I raised my orbit a little too far. Would have gotten 10.36 if I had stopped at 74 km instead of 75,751m.

Edited July 8, 2013 by metaphor

[Tarmenius]

Congratulations on breaking 10, metaphor! And thanks for the video, it's quite helpful.

Danger Will Kerbinson!, that's quite the respectable entry on your first ever Challenge! And welcome to the Forums!

Nurph, your entry has also been added to the Scoreboard. Congratulations on completing the challenge!

mcirish3, I'm looking forward to seeing what your SCIENCE! will show to be the optimal profile for this rocket. You've got more patience than I for the math.