Apollo 11 - orbits and stuff question

[dino1984]

Hi,

As I couldn't find this data (or couldn't understand it ) I would like to ask some questions concerning Apollo 11 mission's orbits.

1. How many orbits, from launch to trans lunar injection does it complete?
2. Was it launch into orbit coplanar with moon orbit?

And one more question about general launching - how to launch into equatorial orbit from non-equatorial launch site?

 

Thanks for answers

[Steel]

29 minutes ago, dino1984 said:

Hi,

As I couldn't find this data (or couldn't understand it ) I would like to ask some questions concerning Apollo 11 mission's orbits.

1. How many orbits, from launch to trans lunar injection does it complete?
2. Was it launch into orbit coplanar with moon orbit?

And one more question about general launching - how to launch into equatorial orbit from non-equatorial launch site?

 

Thanks for answers

I believe they did two "parking orbits" before the TLI.

I'm not sure if it was launched exactly co-planar, but they would have tried to make it as close as possible as plane change manoeuvres are expensive.

Finally, you can't launch into an equatorial orbit from an inclined launch site, the minimum orbital inclination without big plane change burns is given by the inclination of the launch site from the equator.

[Nibb31]

The point of a parking orbit is to give more flexibility on the TLI window. This gave them time to perform a checkout of the vehicle before committing to Go/No Go on the TLI burn. The Apollo missions had two TLI windows, which were after 1.5 and 3 orbits. If they had a No Go on the first window, they had about 2 hours to prepare for the second window. More detail here:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090016334.pdf

The launches were mostly co-planar with the Moon. There might have been a small adjustment depending on the latitude of the landing site, but maybe that was done during the TLI burn and the two midcourse correction burns.

10 hours ago, Steel said:

Finally, you can't launch into an equatorial orbit from an inclined launch site, the minimum orbital inclination without big plane change burns is given by the inclination of the launch site from the equator.

The Moon doesn't orbit the Earth on the equatorial plane. Its orbit has a 5.14° inclination, but the earth's axis is also tilted at 23.4°, so you can combine the two to get a launch window at 28° latitude, which is where Cape Canaveral is. 

Yeah, KSP makes things so much easier with Kerbin having no axial tilt, KSC on the equator, and everything orbiting in a 0° inclination. You can launch to the Mun at pretty much any time. This wasn't true for Apollo.

If they hadn't used a parking orbit, they would have needed to both a launch window that fits both the inclination AND phasing for the TLI burn, which would have been much more difficult to get right.

Edited March 28, 2016 by Nibb31

[dino1984]

Great! Thanks for answer Nibb!

[magnemoe]

7 hours ago, Nibb31 said:

The point of a parking orbit is to give more flexibility on the TLI window. This gave them time to perform a checkout of the vehicle before committing to Go/No Go on the TLI burn. The Apollo missions had two TLI windows, which were after 1.5 and 3 orbits. If they had a No Go on the first window, they had about 2 hours to prepare for the second window. More detail here:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090016334.pdf

This, going to LEO first is standard in KSP for me, simplify stuff a lot.