General Question Transx: Earth to...Earth?

TMac3000

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This is just a little thought process I've been kicking around, and I'd like to get some input on it.


I am sure this is right under my nose, and I'm gonna feel really dumb when someone explains it to me:p


How to do you sling from one planet to the same planet? In other words, is it possible to get Encounter data for Earth in Transx, including hypothetical inclination, without ever leaving orbit?



The reason I want to do this is so that I can use Transx for planning basic LEO maneuvers, like alignment burns and such. I'd like to use "Transx for everything"...fully integrate Transx into my Orbiter experience, and maybe combine it with Burn Time Calculator so I can program all my maneuvers, more like a real spacecraft.


I do suppose that one could more readily use IMFD for something like this, but I want to use Transx for it because Orbiter already comes with with it, and I'd like to be able to write a "Transx for Everything" tutorial.
 

Mojave

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Excel spreadsheet, Pursuit MFD, BurnTimeCalc, DvTools, and IMFD is all you need to do any of this. TransX is entirely useless for your purposes. Why complicate things by using TransX? TransX is completely worthless in this day and age of Orbiting. What you want to do is reinvent the wheel.
 

Mojave

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There, fixed your problem. My calculators will do you just fine for LEO maneuver planning.
 

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BrianJ

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How to do you sling from one planet to the same planet? In other words, is it possible to get Encounter data for Earth in Transx, including hypothetical inclination, without ever leaving orbit?
Just like you would set up a sling around a different planet. From LEO set target to "Escape", next stage set target to Earth and start adjusting dV Prograde, Outward, Pl.Change for intercept.
 

Mipada

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It looks like you're trying to automate launching into orbit. There are better ways. You can watch this:
There is an autopilot MFD that you can use for takeoff, align planes, sync orbit and dock. I think it's here:
[ame="https://www.orbithangar.com/searchid.php?ID=1468"]Autopilot 1.72 with AIRAC and worldwide Airports[/ame]
Google autopilot MFD.
Or, maybe someone can send you in the right direction.
 

TMac3000

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Very nice, but actually that's not what I'm trying to do, and I'm well aware that TransX can't provide launch guidance from the surface--although I did actually try to do it once, and it would be really cool if it had that feature.

My problem is, although TransX can be used to plan pretty much any basic orbital maneuver after inserting into orbit around a particular body (although it's overkill for some smaller burns), you have to do a transfer orbit to that body first and go through the launch (1:2) and cruise (2:2) stages before you can get a hypothetical inclination or other data to show up in Maneuver Mode.

For example: let's say you go from Earth to the Moon using TransX. You set up your TLI plan, do your burn, do your course corrections over the three to four simulated days, and finally enter the Encounter stage.

You can now go into Maneuver mode and set up your insertion burn, fiddling the numbers to get the inclination and orbital altitude you want. You can even get an alignment distance (off-plane distance, as it's called in the MFD) and a figure for how far your periapsis point is from the base by targeting it in Map MFD.

What I want is to be able to use TransX to make maneuvers like that at Earth, without having to come in from another planet. For example, if I wanted to do ISS to Cape Canaveral, I could try to plan a de-orbit burn in TransX, and I'd get an accurate dv of about -100...but it won't draw the base location like it would if I were coming back from Mars or Jupiter, so I can't set my MJD accurately--I have to kind of eyeball it/bodge it, and it's not going to be very accurate. I'll come down in the wrong place.

In fact, our own Blixel illustrated this problem in his Moon-Earth TransX tutorial, wherein he shows that you aren't given periapsis data for your Earth encounter on those trips, because being on the Moon means you are already orbiting Earth. This makes the Moon-Earth trip a bit trickier.

That's the problem I want to solve. Is there a way to "trick" TransX into giving you hypothetical maneuver data other than just periapsis and the relevant date, for a body you are already orbiting, without having go to another planet first?

Now, I know I could just as easily use IMFD or Aerobrake to do something like that, but I'd like to a) be able to do everything in one place, rather that having to visit a dozen different screens for my data, and b) use something Orbiter already comes with, so I can show newbies how to do it without sending them to all kinds of websites...

PS: BrianJ, I tried your solution, and it looks like it sort of wants to work, but the numbers keep dancing around like a madman, and I can't get anything accurate from them. I suspect it has to do with a bunch of division errors stemming from already being at Earth.
 
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