TransX TransX accuracy

[Mister Mxyzptlk]

Laukejas, I just checked your scenario and ran it. The only thing I did was change prograde Vel. to a more accurate figure. I ended up impacting the moon with just my initial burn.

A couple of things:
although it isn't that critical in a moonshot I noticed that your ecc. was small but not zero before you left Earth. Also your Rel. Inc. was not zero. Along with the sloppy estimation of Prograde Vel. It seems to me that you are the inaccurate variable here. GIGO means garbage in garbage out, and if you set up transx sloppy like that what do you expect it to do? You must be inerringly precise with transx or you will never get anywhere with it. Especially to go on planetary missions you must be precise to the Nth degree,(that is til you truly understand how transx operates) because in planetary missions if you are sloppy you will be Gigameters off course.

Course corrections are best done when halfway through your Hohmann, then half of that and so on til your course is stable.
But I must emphasize that your initial burn has got to be right on the mark or you aren't just going to have problems, you also won't be learning how to use transx properly and you will get discouraged.

 

[laukejas]

Thank you very much for your advice

I just completed my first Earth-Mars trip using DGIV with default settings (engine and fuel enough for moon) without refuelling :hotcool: just carried some O2 cargo. At landing at Olympus, I had 3% fuel left for main engine and 5.6% left for RCS. Martian atmosphere is quite annoying for landing! Can't find a proper way to decelerate...

 

[Mister Mxyzptlk]

I assume you used transx? By the way you need to get Aerobrake MFD at the Orbiter hangar for reentry into Mars atmosphere.

[ame="http://orbithangar.com/searchid.php?ID=2139"]AeroBrakeMFD[/ame]

That is the link.

Reenter inverted and you shouldn't have any problems.

 

[laukejas]

Yeah, I used transx Normal takeoff from Earth, trip - according to tutorial found on Youtube, and then 2 aerobraking manuevres on Mars, since there wasn't enough fuel for normal orbit insert. And I'm already using AeroBrake MFD, but thank you! Could you please describe that "reverted reentry"? I heard about it, but don't know what it would accomplish, and how to do it with DGIV.

 

[tblaxland]

Of TransX and IMFD, I believe one uses a patched conics approximation, while the other uses another method (direct integration of the equations of motion?) to determine flight plans.

IIRC IMFD uses both methods, patched conics for flight planning and integration for the map mode. If I'm trying for a sling shot I normally use both TransX and IMFD - TransX to get me in the ball park with respect to flight planning and IMFD to fine tune and execute the burns.