Rocket Science

[Regor]

WARNING! BIG IMAGES AND INSANE SCIENCE!

Hello forum,

So I decided to build a rocket that gets into orbit, WITH SCIENCE.

 

I started with looking at how much dV i needed:

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Once I knew how much dV i needed, I needed to think about the stages:

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Then I did the calculations to find out the Wm/Dm ratio:

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So I needed to know how much fuel I needed using SCIENCE and trial and error:

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Then we needed to start on the lifting stage:

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So I needed to know how much fuel I needed for this stage:

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However, It had way too much dV:

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So we needed to optimise:

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And I found the perfect combination:

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I hope you enjoyed taking a look at this thread,

mabdi36 

[Bill Phil]

Excel is your friend.

[sevenperforce]

I don't use MechJeb, so there's always some variation in dV budget for LKO ascent. So I typically just overengineer my first stage comfortably, and do the math for all the other stages.

QuantumG's dV calculator is hugely useful, unless you're just dying to do the calculations by hand. (QuantumG is one of the regular posters over at the NSF forums.) And even if you do it partly by hand, no one calculates logarithms manually. If I have a lot of dV calcs to do, I write the formulas out in Excel...this is particularly good for optimization problems where I have to iterate over a range.

[Regor]

Just now, sevenperforce said:

I don't use MechJeb, so there's always some variation in dV budget for LKO ascent. So I typically just overengineer my first stage comfortably, and do the math for all the other stages.

QuantumG's dV calculator is hugely useful, unless you're just dying to do the calculations by hand. (QuantumG is one of the regular posters over at the NSF forums.) And even if you do it partly by hand, no one calculates logarithms manually. If I have a lot of dV calcs to do, I write the formulas out in Excel...this is particularly good for optimization problems where I have to iterate over a range.

I really like doing math by hand

[YNM]

I can't yet see the images (stupid mobile operator !), but is this meant for in-game ? Thought this was yet another attempt at making RL rockets.

EDIT : My problems for KSP rockets are usually with the controls; most of the rockets have troubles going at max Q (I think) so one wrong movement and it's done, no space for you today...

Edited July 8, 2017 by YNM

[Regor]

26 minutes ago, YNM said:

I can't yet see the images (stupid mobile operator !), but is this meant for in-game ?

No, it's hard paper math

[YNM]

1 hour ago, mabdi36 said:

No, it's hard paper math

Well, what I was asking is whether this is for Kerbin (in-game) or Earth. 3.3 km/s is waay too low for LEO. Nothing stops you from using abacus in-game. 

Edited July 8, 2017 by YNM

[Regor]

4 minutes ago, YNM said:

Well, what I was asking is whether this is for Kerbin (in-game) or Earth. 3.3 km/s is waay too low for LEO. Nothing stops you from using abacus in-game. 

No its LKO not LEO

I believe it is 9.5km/s in real life

Edited July 8, 2017 by mabdi36

[YNM]

6 minutes ago, mabdi36 said:

No its LKO not LEO

I believe it is 9.5km/s in real life

I know, it is. It wasn't clear without the images as I can't see them back then (now on wi-fi, where imgur and such isn't blocked by stupid internet controls).

[NSEP]

4 hours ago, mabdi36 said:

I believe it is 9.5km/s in real life

You need 9,4km/s to get to orbit IRL, but from my experience in Realism Overhaul, sometimes you could do with 9,1km/s and other days you need 10km/s. So it changes. But 9,4/5 is the ideal amount.