Rocket efficiency

[W. Kerman]

My question is, how much of your weight on the launchpad gets into orbit. Even those mystic SSTO masters can't say 100% of their crafts' mass reaches LKO.

 

So, what is your best Start/End ratio?

 

My best for Launchpad to LKO is 20%

 

My best for LKO to DLO is 33%

[Leafbaron]

I usually design my ships so that the top stage or mission stage has full fuel. They are designed with delta v specific for the mission so I can't waste any on getting the mission stage in orbit. I would say, my crafts are usually 70% - 80% fuel. So basically the same as you. 20-30% of initial mass makes it to orbit. 

[Guest]

IIRC the best on these forums is around 50% to LKO in the latest versions. You should actually see more than 20% given the atmospheric changes reduced the delta-V to orbit from 4.5km/s to 3.2km/s or thereabouts, and at 4.5km/s the usually payload to LKO was about 18%. I haven't really measured it myself, I don't really give any thought to efficiency in stock/vanilla.

IRL you're looking at 1~5%, with 2.5% being pretty decent for kerolox systems like the Soyuz. Make of that what you will.

Edited October 7, 2016 by regex

[Xyphos]

We don't measure payloads in terms of imperial weight, but in terms of atomic mass.

your question might refer to the "payload fraction challenge" in the challenge forums, try looking there for contest claims.

most of my SSTO's carry enough fuel to land on Minmmus or rondevous with an asteroid outside of Kerbin's SOI for refueling;
I prefer to use asteroids honestly, as they can de/spawn as needed, and don't require additional dV to land, just use normal docking maneuvers.

as to answer your question, it varies from vessel to vessel, and that vessel's purpose; there's no set number.

Edited October 7, 2016 by Xyphos

[Aegolius13]

Your post is titled "Rocket Efficiency," but worth mentioning that rockets and planes (especially SSTOs) are going to be be vastly different.  I just returned an SSTO from Laythe and it still had almost 40% of its starting weight.  

That said, payload mass fraction is a whole lot more important than raw mass.  A SSTO spaceplane will hang onto a lot of wings, RAPIERs, empty fuel tanks and so forth, but that's not a good thing in terms of space range efficiency.  On the contrary, unless going SSTO deliberately, you generally want to lose unneeded mass as quickly as possible - hence the importance of staging. 

[Red Iron Crown]

"Payload fraction" is the term you're looking for, and properly speaking you should only include payload mass that reaches orbit for it. Here's the challenge I ran for it for a while (as mentioned by Xyphos above):

Tl;dr: Best SSTO: 58.0%, best disposable rocket: 26.8%. These are highly specialized designs though, more practical designs are generally a good bit lower.

Payload fraction isn't the end-all be-all of efficiency though, another good metric is cost per ton to orbit. Designs optimized for that look a bit different, lots of solid rocket boosters.

[Norcalplanner]

1 minute ago, Red Iron Crown said:

"Payload fraction" is the term you're looking for, and properly speaking you should only include payload mass that reaches orbit for it. Here's the challenge I ran for it for a while (as mentioned by Xyphos above):

Tl;dr: Best SSTO: 58.0%, best disposable rocket: 26.8%. These are highly specialized designs though, more practical designs are generally a good bit lower.

Payload fraction isn't the end-all be-all of efficiency though, another good metric is cost per ton to orbit. Designs optimized for that look a bit different, lots of solid rocket boosters.

And here's the challenge I ran back in 1.0.5 for lowest cost per ton to orbit, limited to rockets only.  Kickbacks are your friend. 

 

[Frozen_Heart]

I actually use 10% as a rule of thumb for my lifters when building, and then gradually push them further and often end up above 15%

[magnemoe]

4 hours ago, Red Iron Crown said:

"Payload fraction" is the term you're looking for, and properly speaking you should only include payload mass that reaches orbit for it. Here's the challenge I ran for it for a while (as mentioned by Xyphos above):

Tl;dr: Best SSTO: 58.0%, best disposable rocket: 26.8%. These are highly specialized designs though, more practical designs are generally a good bit lower.

Payload fraction isn't the end-all be-all of efficiency though, another good metric is cost per ton to orbit. Designs optimized for that look a bit different, lots of solid rocket boosters.

Yes, if you used an airbreathing first stage and rocket second you could go even higher as you would not have to drag the entire plane into orbit.
It would be uneconomical. 
SRB are cheap but heavy on the other hand