Asparagus question from a nerd...

[paradoxh]

Hi all,

I'll keep this brief as I'm at work and being naughty on the internet

I'm sort of nerdy with my KSP as I rather anjoy sitting down with a pen, paper and calculator and actually calculating the delta v of each stage of my rockets BEFORE even placing the pod in the hanger. I like to know the design and what I can expect from it before I launch (no Mechjeb for me!).

My problem is that now I'm at the stage whereby I need to use asparagus staging to put a kerbonaut on the Mun I'm unsure of how to calculate dV for the actual asparagus staging pairs. I've read before that they are calculated the same way as standard 'stacked' stages but this doesn't seem true as in testing in sandbox the asparagus design out-performs what I calculate... Now I'm aware that it's probably my calcs that are off so could someone ever so kindly explain how to calculate the dV for asparagus staging? (I realis that I could use mechjeb but am really trying to avoid it)

Thanks in advance

Para

[Mr Shifty]

Are you doing proper thrust weighted Isp averaging for your engines? Do you have an example calc?

[Stankleberry]

Make sure your calculator isn't broken.

[capi3101]

If you're calculating it by hand, what you do is treat it like serial staging - all that asparagus does is add extra thrust from the other stages as you go. How many stages you treat it as depends on the number of boosters you want to include - if you use a six booster design, it's four stages to orbit; eight boosters, it's five stages to orbit.

Temstar talks about how to build a good asparagus design here; its the basis he uses for his Zenith booster series. Follow his guidelines to get a good engine mix for your payload.

What you then can do is set up each stage equation so you account for the total mass of the previous stage (including fuel). Your target aggregate delta-V for any booster design is 4550 m/s, so you divvy up how much delta-V you want with each stage. For a four stage booster, I usually go with 10% for the first stage, 20% for the second, 30% for the third and 40% for the fourth. For five stages, it's 6.7% for the first, 13.3% for the second, 20% for the third, 26.7% for the fourth, and 33.3% for the fifth). You have your payload, you add the mass of the decouplers and the engine for the stage, and calculate how much fuel you need to achieve your target delta-V by running Tsiokolvsky backwards (keeping in mind the wet-to-dry mass ratio of almost all fuel tanks in the game is 9:1, i.e. M = 9Md). Do this for each stage. Then for an asparagus design, add up all the fuel you need for all the stages, average for the total number of stacks you're employing (7 for a six booster stack, 9 for an eight booster stack), and then select a set of tanks that get you as close to the indicated amount of fuel as possible.

[Odo]

You dont have to use asparagus staging, I personally dont like to I've landed on Duna, Eve, Mun, Minmus, and Ike all without asparagus staging, try pancake staging. Its better looking and more realistic

[KvickFlygarn87]

Well, what's pancake staging? Never heard of it!

[Captain Sierra]

Well, what's pancake staging? Never heard of it!

build a serially staged rocket with a single engine core. Now copy each stage and mount it radially onto it's twin. Basically, it's onion staging without radial decouplers. Typically you have both upper and lower stages with extra radial mounted stuff.

[capi3101]

I.e. it's serial staging with MOAR BOOSTERS.

[SRV Ron]

You can always try the school of hard knocks. Build something and take notes on how well the design works. Find that balance between excessive acceleration and not enough that gives the best launch to orbit performances.

Here are two designs based upon Novapunch parts.

Simple small two stage probe that can orbit Mun or Minmus.

Built up with four place asparagus and eight SRBs. This should be able to go and land almost anywhere.

In orbit. Note fuel available in the remaining asparagus.