I am attempting to build an unrealistic demonstration of orbit alignment, sync and rendezvous. I have shrunk the earth while keeping the same mass. With videnie, I can get a nice animation showing complete orbits around the earth with an orbit time of about 60 seconds. Now, I'd like to show say the STS with an image large enough to see the operation of the RCS and OMS or at least the vessel's orientation (prograde, retrograde and NML +/-) and still see the complete orbit.
I don't think that blowing up the mesh is the solution here. As Loru already mentioned, there will be problems with thruster positions, animations and clipping distance.
You mentioned making a smaller Earth with the same mass. Also not a very good solution.
For an orbital period of 60 seconds, with the same mass you have an orbital radius of ~1524 km. ( I am assuming that your "small Earth" radius is smaller than that). That means that you have a velocity of ~16.17 km/s
At that velocity, a plane change of 1° costs 282.21 m/s. That burn would take the default Atlantis' OMS engines about 10 minutes to perform, which means 10 orbits.
The way I'd go about it is to super shrink the Earth, mass included.
First let's find a radius for the Earth that would have the effect you want compared to the Shuttle's size:
The Shuttle Atlantis in Orbiter has a length of ~38 meters, from the tip of the nose to the very edge of the vertical stabilizer.
Assuming a ratio 1/10 [math]\frac{ship \; length}{planet \; diameter}[/math] means that the radius of the Earth needs to be 190 meters.
(scale comparison)
Now let's assume that you are orbiting at an "altitude" of 10% the radius of the Earth = 209 meters distance from the center. For an (arbitrary) orbital velocity of 200 m/s*, the planet's mass must be:
[math]\sout{ M = \frac{V_{orb}\cdot r}{G}} = \frac{200 \cdot 209}{6.67259e_{-11}}= 6.2644340503463e_{+14} \; kg [/math] *error corrected, see below.
The orbital period will be:
[math] \sout{T = 2\pi \sqrt{\frac{r^3}{GM}}} = 90.28 \; seconds [/math] *error corrected, see below.
*The orbital velocity was chosen so that an 1° plane change would cost ~3.5 m/s - an 8 second burn for the Atlantis.
So to recap:
-Set the radius to 190 meters.
-Set the mass as 6.2644340503463e+14 kg
-Place the STS at a Semi Major axis of 1.1 planet radii, with eccentricity 0.0000
-Get rid of the atmosphere or use the 2006 legacy model to place it a couple of meters above the surface.
---EDIT:
:hmm: Something appears to be wrong with the mass calculation. It seems too small.
It's already too late over here to check it again right now. I will redo it tomorrow and post the correct values.
:tiphat:
---EDIT2:
Ok, I spotted the error. In the mass calculation the orbital velocity needs to be squared.
[math] M = \frac{V^2_{orb}\cdot R}{G}[/math]
Also, the 1/10 ratio is too big. I made a couple of tries and I think that a 1/40 [math]\frac{ship \; length}{planet \; diameter}[/math] ratio is better.
So let's calculate again with these parameters:
Planet R = (40*38)/2 = 760 meters
Orbit r = 760 + (0.1*760) = 836 meters
Orbital period T = 60 seconds
Rearranging the orbital period equation [math] T = 2\pi\sqrt{\frac{r^3}{GM}} [/math] to find the mass.
[math] M = \frac{4\pi^2 r^3}{T^2 G} = 9.602440570475e_{+16} \; kg [/math]
Here is how it looks in Orbiter with videnie:
The orbital velocity is [math] V_{orb} = \sqrt{\frac{GM}{r}} \simeq 87.55 \; m/s[/math], which means that a 1° plane change will cost ~1.53 m/s - a 3.59 seconds burn for the Atlantis.
So to recap:
-Set the planet's radius to 760 meters.
-Set the mass to 9.602440570475e+16 kg
-(The rest the same as before the first edit)
