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EVAMechJeb (2014-02-20)


jamis

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Have you ever wondered just how fast that kerbal was going? Or how high it was over the lunar landscape? Or tried--unsuccessfully--to judge when to fire your jetpack so as to slow your reckless ascent safely?

Maybe it's just me.

At any rate, I finally figured out how to scratch that itch, by adding (limited) MechJeb functionality to EVA'd kerbals.

Try it yourself, and let me know what you think. It's a pretty trivial module (it just adds MechJebCore to kerbalEVA), but perhaps there's more it could be doing? Also, as I said, it is LIMITED: most MechJeb features will not work, but the info windows (at least) work great!

Also, it should go without saying, but I'll say it anyway: this won't work at all unless you also have MechJeb installed.

Download it here: http://jamisbuck.org/files/EVAMechJeb-20140220-0.zip

And because pictures:

eva-mechjeb-1.png

eva-mechjeb-2.png

(Note: I finally could see exactly what an EVA'd kerbal weighs, too: 0.094t!)

(Source is included in the download. License is MIT: http://opensource.org/licenses/MIT)

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Have you ever wondered just how fast that kerbal was going? Or how high it was over the lunar landscape? Or tried--unsuccessfully--to judge when to fire your jetpack so as to slow your reckless ascent safely?

Holy Kilograms Batman! Kerbals weigh 413 Pounds!

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According to Google, 188lbs, or 85.275366kg. Also take into accordance the space suits.

I'm pretty sure 94kg = 94kg. Not sure where either 188 or 85.275366 is coming from here, but if Google thinks 94kg = 85.275366kg, something has gone terribly wrong with its conversion factors.

This on the Mun.... how much will they weigh on Kerbin then.

MechJeb is showing "Vessel mass", which is identical on any body. If their mass is 94kg on the Mun, their weight is 94kg on Kerbin. Not sure about weight on the Mun, though.

Edited by Gaius
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I think the confusion stems from the use of "ton". The "t" in KSP is actually a "tonne", or "metric ton", which equals 1,000 kg. Thus, 0.094t == 94kg, which Google handily translates to approximately 207lb.

NASA tells us (here) that a human space suit weighs about 280lbs "on the ground", with no one in it. If we round things a bit and say a Kerbal (at about 1m tall) is more or less half the height of a human (because, you know, most of us are fully 2m tall), and supposing that mass scales 2x faster than height, we can say that a Kerbal space suit weighs 1/4 of what a human space suit weighs, or about 70 lbs (23.5kg). Subtracting the kerbal suit weight from the total weight (94kg - 23.5kg) we get 70.5kg as the mass of a bare kerbal, or about 155lbs.

So, yeah. Whatever kerbals are, they're dense, but that would follow, given that the gravity of their tiny planet somehow manages to be 1g!

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MechJeb is showing "Vessel mass", which is identical on any body. If their mass is 94kg on the Mun, their weight is 94kg on Kerbin. Not sure about weight on the Mun, though.

Then MJ should have the mass displayed in Newton because weight is the object's mass multiplied by the acceleration that it is undergoing (Example: Earth is 9.58m/s² (at sealevel)).

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Then MJ should have the mass displayed in Newton because weight is the object's mass multiplied by the acceleration that it is undergoing (Example: Earth is 9.58m/s² (at sealevel)).

No, you've got that backwards. Since weight is mass times gravity, weight could be displayed in newtons, but not mass. The SI unit for mass is the kilogram. You cannot display mass in newtons -- if you're talking newtons, you're talking about something other than mass.

Edited by Gaius
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I think the confusion stems from the use of "ton". The "t" in KSP is actually a "tonne", or "metric ton", which equals 1,000 kg. Thus, 0.094t == 94kg, which Google handily translates to approximately 207lb.

NASA tells us (here) that a human space suit weighs about 280lbs "on the ground", with no one in it. If we round things a bit and say a Kerbal (at about 1m tall) is more or less half the height of a human (because, you know, most of us are fully 2m tall), and supposing that mass scales 2x faster than height, we can say that a Kerbal space suit weighs 1/4 of what a human space suit weighs, or about 70 lbs (23.5kg). Subtracting the kerbal suit weight from the total weight (94kg - 23.5kg) we get 70.5kg as the mass of a bare kerbal, or about 155lbs.

So, yeah. Whatever kerbals are, they're dense, but that would follow, given that the gravity of their tiny planet somehow manages to be 1g!

You are forgetting that that is the mass for the spacesuit only. The Kerbals also have jetpacks. The closest thing to a Kerbal jetpack is the MMU, which had a mass of 148 kg. If we apply the same metric, the Kerbal jetpack would weigh 37 kg. Subtracting that from your figure gives 33.5 kg as the mass of the Kerbal, or about 74 pounds. This seems like a slightly more reasonable mass.

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You are forgetting that that is the mass for the spacesuit only. The Kerbals also have jetpacks. The closest thing to a Kerbal jetpack is the MMU, which had a mass of 148 kg. If we apply the same metric, the Kerbal jetpack would weigh 37 kg. Subtracting that from your figure gives 33.5 kg as the mass of the Kerbal, or about 74 pounds. This seems like a slightly more reasonable mass.

Good catch! 33kg seems a much more reasonable mass for a naked kerbal. It makes more sense, now, that they would walk so slowly and clumsily, carrying double their own mass in gear around.

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  • 3 months later...
You are forgetting that that is the mass for the spacesuit only. The Kerbals also have jetpacks. The closest thing to a Kerbal jetpack is the MMU, which had a mass of 148 kg. If we apply the same metric, the Kerbal jetpack would weigh 37 kg. Subtracting that from your figure gives 33.5 kg as the mass of the Kerbal, or about 74 pounds. This seems like a slightly more reasonable mass.

Luckily their EVA fuel is massless...

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  • 11 months later...
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