Launch Efficiency Contest, craft provided !

[Dakitess]

Hi there,

I'd like to suggest a small and easy contest, which is all about launch efficiency, trajectories, gravity turn, etc. You'll find below a Full Stock Craft :

https://cdn.discordapp.com/attachments/706948521735225374/753224100033462372/KSC_-_SLG4_-_MunAr.craft

 

A quick VAB pic of this very basic rocket :

 

What you can do :

- tweak every contextual parts menu : engine's gimbal, booster's power, fuel capacity, fairing jettison option, Autostruts, Rigid connection, fuel consumption priority... Etc.

- modify the staging : fairing separation sooner, synchronize a decouple with the upper engine, etc.

- fly the way you want, provided that you're not using dirty alpacas, bug using, AltF12, etc.

- you can use any AutoPilot mod or script you want : be sure to avoid adding Parts, I know there is Partless version of MechJeb for instance. Otherwise that would add some mass / drag.

- mods are generally okay, they do not alter physic in any way and you're not adding any parts, etc, see previous rules :p

 

What you cannot do :

- obviously, you can't add or remove any parts. And you can't do anything to the Payload.

- do not unlock the upper tank of the last stage, it's here for a reason : you should be able to put that craft into orbit without touching the locked tank, with margin. If you don't, you're in the good place to ask for tips, do not hesitate

- do not use any mods / thing that is altering the Stock Physic.

 

Provide some screenshots you want, but one them must be the Orbit View, after reaching 100x100km circular orbit, minimum, just like the next image :

If you're using some AutoPilot mod, please provide a Screenshot of the settings panel as well, as it's one of the thing that i'm personally interested in : i've never find any one beating me at this challenge using autopilot :p

 

Your goal : preserve as much DeltaV you can ! We will only look at the Stock indicator, at the lower left corner !

 

You should provide : a screenshots of the orbital view showing the 100x100 circular orbit minimum and the Lower Left corner DeltaV Stock indicator, and any other screenshots or information regarding what you've tweaked / change, according to the rules, as well as AutoPilot Settings Panel, if you're using one.

 

Try to use a recent version of KSP, at least from 1.7.1 since this is the one that brought the Stock DeltaV indicator.

Any feedback appreciated if there is questions, suggestions, etc !

 

Edited September 10, 2020 by Dakitess

[EveMaster]

Nice challenge! Is it allowed to add autostruts and/or "rigid connection" or how it is called?

Is it allowed to change the staging? For example put the decoupling and ignition of the next engine into the same stage or deploy the fairing earlier.

Is it allowed to deploy the fairing while still in the atmosphere?

The upper fuel tank of the terrier stage is disabled. Can this fuel tank be enabled for the deltaV readout of the scoring?

 

The craft is a quite straight forward design with a very high TWR and plenty of delta-V, so less experienced players should also be able to put the craft into orbit.

I suggest another play mode with a seperate leader board in addition to the maximum remaining delta-V readout: Cheat the gravity to a higher factor and still put the payload into orbit. The gravity factor is the score.

Edited September 9, 2020 by EveMaster
Some more questions and a suggestion

[Dakitess]

Very nice questions indeed !

- Yep, you can tweak the Rigid Connection thing and / or AutoStruts.

- Yep, you can change the staging, good one, did not think about it !

- Yep, you can do whatever you want during your flight, except for bug-using, AltF12 and this kind of thing :p

- Right, I did not remember that I locked this upper tank : actually, it is a way to "dimension" a good ascent, you should not have to use it. If you do, well, you might want to work on your trajectory and ask for advises  I prefer that we let that untouched, as it's my fault and maybe some people already Download the craft with this aspect, or won't read the fact that they MUST unlock to get same DeltaV read-out : let's have it lock, if it's okay for you !

- Love your suggestion ! But it sounds a bit strange to me haha :p Are you looking for a more challenging rocket instead ? Indead the goal was that anyone should be able to put the craft in orbit, without unlocking the Tank, so that they won't be frustrated and still have a proper DeltaV result that they can then try to improve, launch after launch, tips after tips.

I'll add some of this information in the OP !

Looks forward to see your entry :p

[EveMaster]

3331 m/s left. The fuel tanks is still disabled.

Spoiler

I increased the thrust on the SRBs to 100%. Throttle during the entire ascent at 100%. Very shallow ascent.  A bit above prograde when above the thickest part of the atmosphere to profit from body lift. Back to prograde when there is no more lift higher up. Only a very small circularisation burn.

 

[dnbattley]

11 hours ago, EveMaster said:

3331 m/s left

Good lord that's efficient. Bravo. The best I could do after 3 attempts was 3119...

[Superfluous J]

I'll toss my 3014 first attempt in there just to give another data point. I won't launch it 100 times to tweak because my patience is low tonight.

However, I'd just like to say that I really like your launcher. Very efficient. I barely felt the need to throttle down at all and that was just near the end of the first LFO stage which is hard to avoid anyway.

The only changes I made were:

Move engine from stage 10 to stage 9, to go with the SRBs and clamps.
Move decoupler from stage 7 to stage 6 to be with its engine. I just prefer it this way.
Same with engine from stage 4 to stage 3, though I never got that far in the flight.

 

Edited September 11, 2020 by Superfluous J

[IronMaiden]

I suppose I should post it here too

 

Here's mine with 3446m/s remaining at 100km circular orbit.

Changes: I maxed thrust and gimbal range on everything and rotated the craft 5° to the east. Changed fuel flow priorities, drain from bottom up on both stages.

Flight: Max throttle and lock surface prograde after clearing the "tower." Circularize and push apo to 100km at around 30km. Stage fairing once in space. No mods.

There's room for improvement, I could've been more aggressive with the gravity turn.

Edited September 11, 2020 by IronMaiden
insert image

[IronMaiden]

46 minutes ago, Superfluous J said:

I barely felt the need to throttle down at all and that was just near the end of the first LFO stage which is hard to avoid anyway.

 

 

Throttling down is not a good idea, in fact you should maximize thrust on the SRBs too, more thrust means less Δv to orbit as less is lost to gravity. There's no changing your engine mass so take advantage of it. You should be max throttle until your apo reaches 100km, and at orbital velocity at that point as well. Gravity turn should be as aggressive as possible without needing a positive angle of attack to prevent falling back to the planet.

[Dakitess]

Throttling down is indeed very rarely a good idea, it only means you could have chosen a more suitable engine, lighter / with better ISP. Or you can take benefit from higher TWR which always is a plus to avoid Gravity Losses, by FAR higher than Atmospheric Drag.

This challenge is here to promote the Gravity Turn as it makes a HUGE difference and show how much the "don't go too fast in the atmosphere" is a very wrong way to ascent.

My initial entry :

I actually thought it would be better to loose slightly on the agressive curve to allow for less drag cumulated during minutes and minutes, even at 0.01-0.02 m/s/s and that would allow to perform a 70km Apo, from stage the fairing to take benefit from a push with less dry mass as possible, getting the Pe at 100km and then circularize again.

Don't know if it's still interesting to only aim for 70km, stage fairing, raise Pe, especially if you flatten the curve even more.

Anyway, i'll have to improve my ascent, but damn, 3446 m/s is one hell of a score.

Good job to the other players, already some very nice entries, 3331 m/s for EveMaster, I did not get that high in my attempts !

This launcher is part of my "Suivez l'Guide" tutorial which is, I humbly believe, one of the most complete and illustrated I've seen. I'm giving Crafts to download, saves with exercices, etc. This rocket is used to show the Gravity Turn as well as the Mun Round-Trip, with some margin but not that much for a new player. I give some referential values at each step to see if they're on the track or where they can specifically improve

Edited September 11, 2020 by Dakitess

[Superfluous J]

1 hour ago, IronMaiden said:

Throttling down is not a good idea, in fact you should maximize thrust on the SRBs too

Throttling down while sideways is not a problem; you're not fighting gravity anymore.

I missed that the SRBs were throttled down. Had I noticed I would have pegged them at max for sure.

[IronMaiden]

12 minutes ago, Superfluous J said:

Throttling down while sideways is not a problem; you're not fighting gravity anymore.

Sort of, as long as you're at orbital speed. However, remember the Oberth effect, it's more efficient to raise your apoapsis from 30km than it is from 70km even though you'll get a little more drag. As a general rule you shouldn't throttle down until you're raised your Apoapsis to the desired altitude and you should be as aggressive as possible with your gravity turn. In a craft that has been properly designed to reasonably limit drag and have a reasonable TWR, you often circularize at 30-40km. In more extreme examples with crazy high TWR you can circularize at 20km or even 10km but you'd need to abuse the aero and shock heating model a bit for that to be the most efficient ascent.

42 minutes ago, Dakitess said:

I actually thought it would be better to loose slightly on the agressive curve to allow for less drag cumulated during minutes and minutes, even at 0.01-0.02 m/s/s and that would allow to perform a 70km Apo, from stage the fairing to take benefit from a push with less dry mass as possible, getting the Pe at 100km and then circularize again.

Don't know if it's still interesting to only aim for 70km, stage fairing, raise Pe, especially if you flatten the curve even more.

That's an interesting idea, but I'm not sure at what fairing mass it'll start being worth it. As I mentioned above, there's also the Oberth effect. If your fairing is half your payload mass then yeah it might be worth it to do the last 100m/s or so at a lower speed with a significantly lower mass but with your setup here I don't think it's worth it. I'd love to be wrong though

[Dakitess]

I've tested, Oberth Effect seems to beat the benefit from limiting the Ap at 70km. In addition, the ascent is even flatter, leading to more atmospheric drag : better push the AP directly to 100km !

Here is my last attempt so far, 3444 m/s :

Is it still possible to embed Imgur Album here on the Forum ? Here are some screenshots taken at some specific steps : https://imgur.com/a/Gz0tVXo

Edited September 11, 2020 by Dakitess

[IronMaiden]

On 9/11/2020 at 1:02 AM, Dakitess said:

Here is my last attempt so far, 3444 m/s

Very nice! You went a bit higher than I did, maybe 2m/s worth?

[Dakitess]

Naaah did not try again after this 3444 m/s, you still have a record :p

What's up, the other players ? do you manage to improve your ascent ? Even if it's not the record, do not hesitate to post your entries with some informations and / or question if you want some help ! You can see that you can clearly improve by a large margin (+/- 300 m/s) over a standard not optimized ascent ! 

[EveMaster]

I now managed to reach 3447 m/s in orbit.

On my previous attempt, I did not know that you are allowed to rotate the craft. I rotated it by about 2-4 degrees to the east. SRBs and throttle on full all the time. Switching to prograde after reaching 15 m/s. Staying on surface prograde during the entire burn. Very shallow ascent profile.

Pictures of my ascent:

Spoiler

 

Edited September 25, 2020 by EveMaster
Corrected remaining delta-V

[Dakitess]

Yeah It was not clear wether you were allowed to rotate the craft, but I think it's totally okay. It just simplify a liiiiitle bit the pitch over, you would be able to do the exact same ascend with a vertical liftoff, just a bit more difficult to trigger.

3447 m/s ! Damn, you now have the record, good job  I'll have to try again then :p

@IronMaiden, you know have another competitor :p