Average travel time to Eeloo?

[NeverEnoughFuel!!]

Well as the title says, what is the average travel time to Eeloo? No slingshots, no enormous amounts of fuel i.e. fast travel things... I have a ship on route there, and so far without parking orbit, and with help of KER, TWP and KAC it costed me about 2400ish delta V, but the travel time is almost 4 years... did I mess it up? I don't mind the waiting, I have enough (I think) delta V, for capture, chemically powered lander for landing and grabbing science, and hopefully return... 

[GoSlash27]

NEF,

 According to my spreadsheet, the average hohmann transfer to Eeloo is 3 years 308 days. Average DV is 2,100 m/sec, neglecting inclination change (which is substantial). Eeloo's orbit is highly elliptical, so there's a lot of spread.

 Doesn't look to me like you screwed anything up.

Best,
-Slashy

 

Edited November 29, 2016 by GoSlash27

[The Aziz]

Everything depends on everything. You use more d-v, you get there sooner. You use less, you get there later - because fly-by velocity is much lower, when you're eg. at your sun apoapsis and Eeloo is just passing by.

[Starman4308]

That sounds about right.

An extreme-case idealization of transfer duration is to consider a Hohmann transfer from 0 to a circular orbit of radius 1.

Spoiler

 

Parent standard gravitational parameter u = 1 (to make math simple; it divides out anyways)

Destination SMA = (apo + peri / 2) = (1 + 1 / 2) = 1

Destination period: T = sqrt(SMA^3 / u) = sqrt(1^3/1) = 1 ^ (3/2) = 1

Transfer SMA = (apo + peri / 2) = (1 + 0 / 2) = 0.5

Transfer period: T = sqrt(0.5^3 / 1) = 0.5 ^ (3/2) = 0.354

Half a transfer period (periapsis to apoapsis) = 0.177

 

Thus, in the extreme that you start from very close to the parent body relative to the destination, transfer period will be 18% of the destination's orbital period (and it works in the other way too). 18% of Eeloo's period is about 3 years; give or take a fudge factor for starting from Kerbin instead of the center of the sun, plus Eeloo possibly being near its apohelion, plus or minus a bit for transfer not being a perfect idealized Hohmann transfer, and 4 years is very reasonable for a Kerbin-Eeloo transfer.

[NeverEnoughFuel!!]

Thanks guys, my travel time is 3 years 389 days, I guess it could be a bit sooner/faster but the Jool got in the way, so I had to try a bit harder to "miss" it... about 2100 ejection velocity is right on, and inclination change was about 360ish... It's nice to know I didn't screw it up... ... my pilot is sleeping and soaking in radiation ... let's hope he will not be cooked until he gets there...