Xenon Gas & Total Mass of Ship to Delta V

[blueduckraider50]

Does anyone know how to calculate the total Delta V I would get from my Ion engines with the spesific amount of Xenon Gas I got and the total mass the ship has.

I know MechJeb does this for me, but I forgot to attach it to my ship, so I wanna learn how to do it manually so I can save time.

(My ship has 21.43t Mass and 27200 Xenon Gas)

Thanks in advance.

[NASAHireMe]

Tsiolkovsky's Rocket Equation is the single most important equation you need to know for KSP.

According to the Wiki, xenon gas has a density of 0.1 kg/unit, so your gas weighs 2720 kg, or 2.72t.

dV= 4200*9.82*ln(21.43/18.71)

Edited January 14, 2015 by NASAHireMe

[Anquietas314]

According to the Wiki, xenon gas has a density of 0.1 kg/unit, so your gas weighs 2720 kg. That's a .... ton of Xenon. are you sure you didn't mean 2720 Xenon gas units?

Going by the 21.43 tonnes of ship, and the fact xenon only comes in 400 and 700 quantities (assuming you launch with full tanks - why wouldn't you), I'd say the number OP stated was correct. To save OP the effort (and messing up the calculation):

deltaV = 9.82 * 4200 (I_SP) * ln(21.43 / (21.43 - 2.720)) = 5598m/s give or take.

Note that the constant in KSP is 9.82, not 9.81 as in Tsiolkovsky's equation. It has nothing to do with gravity though.

[NASAHireMe]

Yeah, nvm. That's a huge ship to be powering with Xenon, btw. My probe weighed less than a ton, so my single Xe tank was more than enough dV.

Yeah, it comes out to 5598 dV.

[Anquietas314]

Yeah, nvm. That's a huge ship to be powering with Xenon, btw. My probe weighed less than a ton, so my single Xe tank was more than enough dV.

One would hope the ship has more than one ion thruster . If not, dear god add like 20+ of them! You'll be there for many hours if not days of real time with 4x physics warp otherwise. Still, for ships that size you should generally use nuclear engines for efficient travel. Using ion thrusters means huge part count and either absurdly long burns, or even higher part count.

[Pecan]

I look forward to the single-engine, real-time Moho transfer video.

(Well, it'll be more interesting and useful than most of them, if it works)