Flight Question Altitude as a function of longitude

[bande]

as you surely know, before any docking, taking note of your target's altitude as it crosses the desired rendez-vous point is required.
but I was wondering... if in OrbitMFD we have every orbital data we may need, shouldn't we know in advance target's altitude at a certain longitude?
this way we wouldn't have to wait the target to reach the rendez-vous point, and we could perform orbital corrections without wasting time in waiting!
so does anyone know what is the function f so that Alt = f(Trl)?

 

[RisingFury]

It sounds like you're talking about non spherical gravity source... unfortunatelly Orbit MFD doesn't take it into account. If you don't mind the slighly less realistic setting, you can turn that option off and the PeA and ApA won't dance around so much...

 

[jarmonik]

as you surely know, before any docking, taking note of your target's altitude as it crosses the desired rendez-vous point is required.
but I was wondering... if in OrbitMFD we have every orbital data we may need, shouldn't we know in advance target's altitude at a certain longitude?
this way we wouldn't have to wait the target to reach the rendez-vous point, and we could perform orbital corrections without wasting time in waiting!
so does anyone know what is the function f so that Alt = f(Trl)?

I am not sure what you are trying to find out but it sounds like you talking about Lambert's intercept problem. There is a great deal of information available from the internet about the subject. Also a good site to visit is [ame="http://en.wikipedia.org/wiki/Category:Celestial_mechanics"]Category:Celestial mechanics - Wikipedia, the free encyclopedia[/ame]

This will take you nowhere but the function you are asking is: Alt = SMa*(1-Ecc*Ecc) / (1+Ecc*Cos(TrL-LPe)) - Planet_Radius

 

[Rtyh-12]

What this guy means is that you have the data to calculate what the target's altitude is at a specific point in your orbit. He's just asking how to calculate it. I think jarmonik answered this correctly but I don't know, I'm no space mathematician!

---------- Post added at 18:24 ---------- Previous post was at 18:23 ----------

Instead of having to calculate it ourselves, we can get lazy and ask Martin to add this function into the Orbit MFD!

 

[Izack]

I think jarmonik answered this correctly but I don't know, I'm no space mathematician!

It's only algebra... :lol:

That function will work. All of the information required is available in Orbit MFD except for the longitude at intercept, which you would get from SyncOrbit MFD or whichever tool you will use.

For the ISS, though, the information from Orbit MFD isn't accurate enough to use (very low Ecc and only 4 significant digits.)

Ex.
6.735Mm(1-0.0009^2) / (1.0009 cos(231.96°-326.64°)) = 6.735Mm
(From the "DG Mk4 in orbit" scenario.)

 

[bande]

I am not sure what you are trying to find out but it sounds like you talking about Lambert's intercept problem. There is a great deal of information available from the internet about the subject. Also a good site to visit is Category:Celestial mechanics - Wikipedia, the free encyclopedia

This will take you nowhere but the function you are asking is: Alt = SMa*(1-Ecc*Ecc) / (1+Ecc*Cos(TrL-LPe)) - Planet_Radius

great, THIS is what I meant!
I don't know anything about add-on developing, but having a MFD doing this would be really cool!