TransferMFD Problem with Moon Intersection

[Jason210]

Hi

I know there are better MFDs for this but I am using Transfer at the moment because it's an easy way to familiarise myself with what's going on.

I have followed the instructions for this MFD and the first time I used it, it got me to the moon. However, on every subsequent use for some reason I am missing the moon. The problem occurs towards the end of the burn when my orbit is extending out to match the HTO. When my orbit is about halfway, the predicted position of the moon suddenly starts to move away from the gray line, out of the HTO, such that by the time the burn is complete, the moon's final position is 60-70 degrees ahead of the gray intersection line, and obsviously there's nothing I can do.

I have tried this several times now and keep getting the same result. The consistency of the error suggests there is something I'm doing wrong but I can't think what it is.

Anyone else know?

 

[PhantomCruiser]

Umm, I've had this before, but it was 2 years (or so) ago. I don't remember what I was doing to cause it. Sometimes I've found that using time compression to get me to the TLI window will cause TransferMFD to act very strangely. I got into the habit of quicksaving about a minute before TLI, so I could always come back to that point when needed.
I usually start the TLI burn with the Prograde AP selected, about a minute later I'll use the [5] key on the numpad to cancel it and then kill the burn when Dv drops to near zero.

 

[Jason210]

Thanks.

I'm using Dan's Arrow freighter and with that the burn takes longer than 1 minute. I wonder if that's the problem?

I also thought time compression might be the problem so I've done this without time compression but the problem is identifical.

 

[Grover]

Hi

I know there are better MFDs for this but I am using Transfer at the moment because it's an easy way to familiarise myself with what's going on.

I have followed the instructions for this MFD and the first time I used it, it got me to the moon. However, on every subsequent use for some reason I am missing the moon. The problem occurs towards the end of the burn when my orbit is extending out to match the HTO. When my orbit is about halfway, the predicted position of the moon suddenly starts to move away from the gray line, out of the HTO, such that by the time the burn is complete, the moon's final position is 60-70 degrees ahead of the gray intersection line, and obsviously there's nothing I can do.

I have tried this several times now and keep getting the same result. The consistency of the error suggests there is something I'm doing wrong but I can't think what it is.

Anyone else know?

its been a while since i last used this MFD (i use LTMFD more because i got lazy ) but ill have a go

i dont think its a problem, just set up your HTO as per Martin's guidance in his tutorials, do the burn (and ignore that the moons predicted position moves), just concentrate on getting the dV to 0. once you're on that, hit HTO again to hide it, and you should come right close to the moon

its just a mathematical bug, due to the way the MFD works, it will feed back that "error", but it doesnt mean anything, just hold true to your initial trajectory calculation (assuming you were in a nice stable orbit at least) and wait 3 days until the moon starts to capture you

good luck man!

---------- Post added at 08:47 AM ---------- Previous post was at 08:45 AM ----------

Thanks.

I'm using Dan's Arrow freighter and with that the burn takes longer than 1 minute. I wonder if that's the problem?

I also thought time compression might be the problem so I've done this without time compression but the problem is identifical.

taking longer than one minute is perfectly normal, you have to speed up by more than 3000 m/s

and btw:
Welcome to the Forum

 

[Jason210]

Yes, you're right - the MFD graphics can be ignored after the brun has started.

Cheers!

 

[Grover]

aye, just have a little faith in the numbers, and Martin's coding

once youve got the hang of that, you'll find LTMFD or IMFD which makes it a million times easier when youve learned them, its literally a case of open mfd, press 3 buttons and it flies itself there... kinda ruins the fun a bit though

 

[flytandem]

here's a quick youtube I made for transfer

At about 2:35 thru 2:45 in the video is what you are asking about.

 

[blixel]

Having just completed an entire tutorial on this topic, I'm very familiar with TransferMFD. Have a look at this tutorial and see if it addresses your problem.

[ame="http://orbithangar.com/searchid.php?ID=5268"]Earth to Moon: An Orbiter Tutorial[/ame]

 

[Jason210]

Thanks for all the help!

It's a fun MFD I think, but I had to use TransX to get back to earth. I intend to learn all of them.

 

[redneck]

is there a lesson on how to use transX anywhere for xr5?

 

[garyw]

The one above will work as it doesn't matter what craft the technique is applied to.