CTV Questions

[Nemoricus]

After the Orbiter Forum Space Station project introduced me to the CTV/ATV vessels, they have rapidly become two of my favorite ships to fly. Don't ask me why. I just know that I like them.

Nice job by Well and NoMatter.

However, I do have some questions, some relating directly to the vessel, others to missions using them.

1. The manual mentions jettisoning the fairing on the capsule before deploying the parachutes. I've looked through the documentation and I can't find the key for it. The French reentry tutorial suggests that it's 'J', but that doesn't work. Is there in fact a key to do this?

2. I've seen several mentions of a CTV MFD, but I can't find it. Does someone have a link to it? It doesn't seem to be included with the spacecraft.

3. The documentation mentions the possibility of using the ATV2 and CTV in conjunction for a long duration lunar orbit mission. The procedure is to launch the ATV2, place it in lunar orbit, launch the CTV, and then rendezvous in lunar orbit. Is there a good way to plan the launch times of the two vessels and the orbit of the ATV2 to simplify the rendezvous?

Just for clarification. I'm thinking that of using a 100 km, circular, retrograde orbit for the lunar mission. Inclination is an open question. Also, I'd like a method that works reasonably well with non-spherical gravity sources.

 

[Shadow Addict]

I don't have any answers, but I wanted to say that I've also starting using the CTV and ATV a lot because of the OFSS missions. They are definitely among my favorite few addons now.

 

[astrosammy]

To jettison the Service Module, I think you need to press CTRL 5 and J. The keys should be in the manuals.

Yeah, the CTV is a great ship. Only the aerodynamics are not that great, someone really needs to translate the tutorial.

 

[Nemoricus]

To jettison the Service Module, I think you need to press CTRL 5 and J. The keys should be in the manuals.

This is true, but it doesn't answer my question. There is a fairing on the capsule itself which should be deployed before you deploy the parachutes. It's the top part of the cone.

 

[astrosammy]

I just took a look again, it seperates when pressing CTRL + 0 to open the Drogue chute.

 

[Nemoricus]

I noticed that. However, the documentation makes it sound as if you can separate the fairing before deploying the drogue, but it does not list any way to do so.

 

[tblaxland]

3. The documentation mentions the possibility of using the ATV2 and CTV in conjunction for a long duration lunar orbit mission. The procedure is to launch the ATV2, place it in lunar orbit, launch the CTV, and then rendezvous in lunar orbit. Is there a good way to plan the launch times of the two vessels and the orbit of the ATV2 to simplify the rendezvous?

Just for clarification. I'm thinking that of using a 100 km, circular, retrograde orbit for the lunar mission. Inclination is an open question. Also, I'd like a method that works reasonably well with non-spherical gravity sources.

Assuming you are launching from Kourou, you will be able to launch directly into the Moon's orbital plane. A straight forward in-plane transfer will put you into a 6.7° inc lunar orbit (relative to the lunar equator). Put an ATV2 in that orbit and see how fast its LAN precesses. You will want to launch the CTV one lunar orbit later (27.32 days) less some amount to take account of the precession. The attached graph is based on a precession rate of 1°/day westward. Simply adjust the slope of the LAN line according to whatever precession rate you measure.

EDIT: I can't seem to upload pictures at the moment, I'll again shortly.
EDIT2: Here it is:

 

[Nemoricus]

Okay. Let's see if I've got you right.

1. Launch ATV2 into lunar plane.
2. Lunar transfer, aiming for an orbit with an inclination of 6.7 degrees relative to the equator of the Moon. I suppose that a 173.3 degree orbit works just as well, right?
3. Note the longitude of the ascending node.
4. Advance one day. Note new longitude of the ascending node. Find the difference between the two. This gives the precession of the ascending node per day.
5. Advance time until the ATV2 orbit will be back to its starting LAN in the time it takes for the CTV to transfer.
6. Launch CTV into lunar plane.
7. Lunar transfer. Correct during the transfer to ensure that the CTV arrives in the plane of the ATV2.
8. Rendezvous with the ATV2 normally.

The rest should be relatively simple. However, figuring out return trajectories is a bit of a pain. IMFD is not the easiest thing for this.

 

[tblaxland]

5. Advance time until the ATV2 orbit will be back to its starting LAN in the time it takes for the CTV to transfer.

What you are calculating is the time when the LAN of the transfer plane will be aligned with the LAN of the ATV2 plane. That is what the graph above shows. The launch date should be approx 4 - 4.5 days before that time.

 

[Nemoricus]

I think I got that. Essentially you want to launch so that in the time it takes to reach the Moon, the plane of the transfer orbit and the plane of the ATV2 will coincide.

I noticed that no one said anything about the CTV MFD.

Also, is there a way to jettison the fairing on the capsule separately from parachute deployment?

 

[astrosammy]

I just found the MFD in an old version, and propably you can seperate the fairing in that:

http://orbiter.mustard-fr.com/addons/CrewTransfervehicle-Pegasev1.0.zip