planetocentric distance and altitude above mean planet radius

[jimm]

I spent some time searching for a verifyable method of converting my desired Periapsis Radius into a quantifiable altitude above the earth and this has proven quite elusive.

I can toggle the radius, apoapsis and periapsis data display between
planetocentric distance and altitude above mean planet radius but the author provides no reference to making the calculation myself so I can insert at a specific periapsis altitude and make an orbital transfer in the exact plane of my hyperbolic ejection; Ref TransX.

Any ideas? Any information is helpful especially if there is an MFD that will perform orbital calculations.

 

[Tommy]

All you need is the planet's radius. All planets are treated as being perfectly round (as far as altitude and landing are concerned). The easy way to find a planet's radius is:

1. While landed in any ship, open Open OrbitMFD. Press <DST> to show altitude, not radius.

2. You will see that you have some altitude, this is because altitude is calculated using the ships origen, not it's landing points. Remember this value, I'll call it "ship hieght".

3. Press the <DST> button to show Radial, not altitude. Subtract the "ship hieght" and you have the planets mean radius.

Alternately, you can look at the planet's config file, I believe it's radius will be shown there.

After that, it's simple addition/subtraction. Planet Mean Radius + Altitude = Orbital Radius.