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Old 02-01-2011, 02:44 AM   #16
Mister Mxyzptlk
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Are you saying you still didn't get to Mars? I think you are making way to many assumptions based on an incomplete comprehension of orbital mechanics.
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Old 02-01-2011, 03:38 AM   #17
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I have no problem getting to Mars, Jupiter, or even Neptune. I never have and did it with my first try weeks ago with TransferMFD. Only when I read that Transx was capable of doing off-plane transfers did I become interested in it, and I've flown to Mars, Jupiter, the moon, the ISS, and various other sundry locations with it, from launch and sun orbit. I haven't tried slingshots yet, but I'm certain I'll be tackling that eventually.

My problem was trying to figure out how to plan an off-plane transfer from Transx while sitting in an off-plane orbit, without doing a plane change while in orbit or waiting until leaving the Earth's SOI to perform the off-plane transfer. However, it doesn't seem possible with Transx for the reasons Flytandem explained, and not necessary based on my experiments with Orbiter.

My observations and results were actual flight parameters that I keyed into Transx with a complete plan on the scenarios to Mars. The orbit ejects I performed were actual burns, and the numbers I provided were directly from the OrbitMFD. I don't know that I made any assumptions, and any lack of comprehension of mechanics would then be on the Transx creator. I tried to keep all parameters equal, with the exception of the one for which I wanted the results. For example: In order to compare the final values I provided in the orbit eject scenarios, I wanted to make certain that the only thing different was the time of day I performed the ejection. Everything else remained the same and I posted the results.

In 2 of the scenarios, I actually performed the burn and posted the results from OrbitMFD. In the other two scenarios, I created plans in Tranx and posted the estimated values from Transx.

It was a fun learning experience to say the least, and a nice reminder that the theory of relativity applies even in Orbiter.

I think the most fun thing I did this weekend, though, was fly to Mars, orbit Mars, transfer to Phobos, and land on Phobos. I was successful except for the landing, whereby my spacecraft descended into Phobos and came to rest at the very center, where I got stuck and couldn't get out. Kind of funny, actually, and it ruined my plans for a return to the earth. You should try it and let me know your results. I have replaced the original meshes for Phobos and Deimos, so I'm not certain if the issue is with those meshes, or if it is an issue with Phobos in general.

Try it and let me know what you find.
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Old 02-01-2011, 05:19 AM   #18
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I don't think Flytandem said it couldn't be done. Maybe I am not clear on the concept. But I did it. I have done it numerous times, in fact when I first learned orbiter it was the only way I got to Mars cause I didn't understand plane changes. I mean at my first mid course I had to add a bit of plane change and outward so Mars and the DG would be at the same place at the same time as it were, but I was still way out of plane. As I said, you increase deltav til the green line coincides with the yellow doted line after tweaking prograde vel. to as close as you can get it. Then at about halfway there you do a mid course correction, but you never come close to aligning planes, and then a few more on the way. I came in completely off plane at about 50+ degrees inclination. I did it three times before I gave you the rough plan. I never went into a "solar" orbit. I made it to Mars totally off plane and then burned to capture.

Last edited by Mister Mxyzptlk; 02-01-2011 at 08:48 AM. Reason: spelling
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Old 02-01-2011, 06:23 PM   #19
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Here is a screen shot using the excellent Videnie utility, of an offplane transfer to Mars from the stock DG in orbit scenario. As you can see it is way out of plane, about 6.5 degrees relative inclination, and I have marked the orbit intersection points. Is this what you are trying to do?
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Old 02-01-2011, 06:28 PM   #20
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Originally Posted by Mister Mxyzptlk View Post
 I don't think Flytandem said it couldn't be done. Maybe I am not clear on the concept. But I did it. I have done it numerous times, in fact when I first learned orbiter it was the only way I got to Mars cause I didn't understand plane changes. I mean at my first mid course I had to add a bit of plane change and outward so Mars and the DG would be at the same place at the same time as it were, but I was still way out of plane. As I said, you increase deltav til the green line coincides with the yellow doted line after tweaking prograde vel. to as close as you can get it. Then at about halfway there you do a mid course correction, but you never come close to aligning planes, and then a few more on the way. I came in completely off plane at about 50+ degrees inclination. I did it three times before I gave you the rough plan. I never went into a "solar" orbit. I made it to Mars totally off plane and then burned to capture.
And your method does work, but it does arrive at Mars somewhat well off-plane. I think I intercepted at about 57 degrees when I tried it.

The problem I was having was not that I couldn't get to Mars, it was that in Transx I couldn't plan the off-plane portion of it using the orbit eject function that Flytandem explained in one of his videos. As he explained, he couldn't get the planned orbit and the planned escape to match up on that screen, which were the same exact results I was getting. Therefore, he concluded that it's best to do the plane-alignment during ascent, which I've also successfully achieved on numerous occasions with Transx, MapMFD, and my favorite, LaunchMFD.

And, often, when I plan the off-plane trajectory from Transx using a combination of all 4 parameters, the maneuver mode will orient me retrograde to earth for the burn, and in some cases, orient me directly toward earth. As you can imagine, the results are disastrous for me, and a nice fireworks show for observers on the ground. If, however, when I plan I don't add outward velocity or plane change velocity, then transx maneuver mode will orient me prograde and all is well.....except I have to replan once I exit earth's SOI, thereby planning a new route from that point that includes adjustments for plane change and outward velocity in order to arrive at Mars at a reasonable inclination.
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Old 02-01-2011, 06:30 PM   #21
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Whew! I am so relieved you made it off plane. A two plane transfer is the best, I usually plan to have the node halfway there.

Last edited by Mister Mxyzptlk; 02-01-2011 at 06:32 PM.
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Old 02-01-2011, 06:37 PM   #22
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Originally Posted by Mister Mxyzptlk View Post
 Here is a screen shot using the excellent Videnie utility, of an offplane transfer to Mars from the stock DG in orbit scenario. As you can see it is way out of plane, about 6.5 degrees relative inclination, and I have marked the orbit intersection points. Is this what you are trying to do?
Cool. I use Videnie as well. Neat little utility.

And yes, that's what I'm wanting to do, and can do as long as I don't use outward or plane change velocity in Transx while in parking orbit around earth. When I do, Transx will often orient the little x in maneuver mode in a retrograde direction. As long as I leave plane change velocity and outward at 0 during that stage of planning, I'm ok. But, I have to replan later, usually when I leave earth's SOI, since the trajectory it is on is usually way off, at least from the standpoint of the "Encounter stage".

What I've decided best to do is escape, then plan, that way I don't have to do it twice.
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Old 02-01-2011, 06:44 PM   #23
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At the risk of offending you I have to say that you don't know what you are doing then because the plan I used ONLY used prograde vel. and outward vel. to set up the trajectory you saw in the screenshot. I didn't use manuver mode, I used escape mode, so just what are you doing? Used properly transx should never indicate retrograde direction. You don't even use the bullseye view for the ejection. You just set it prograde in the standard DG auto pilot. Manuver mode is just confusing you, don't use it til you are more familiar with transx.
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Old 02-01-2011, 07:36 PM   #24
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Precisely... As long as you leave "plane change" alone during orbit, it works fine and dandy. But, add plane change and watch what happens. Sometimes it does and sometimes it doesn't go retrograde. But it never goes purely retrograde - Just enough to lower the orbit significantly enough to cause a crash. Additionally, it happens sometimes with an ISS intercept out of plane. Same thing happens often when you add "plane change" velocity. What it amounts to is transx is best used outside orbit, or like default Orbiter MFD functions, best used in-plane while in orbit. In that sense, transx is no more useful than TransferMFD as both will get you there easily. The only real benefit for transx over TransferMFD is the ability to do off-plane transfers well away from interfering gravitational forces, and to plan slingshots.

I'm not confused with maneuver mode. I was simply experimenting with it in order to achieve my goal, just as I experiment with other functions in Orbiter. Some work, some don't. Bullseye doesn't, but I was hoping I was doing something wrong rather than it being a limitation.

Outside my experiments, I am handling maneuver mode exactly as all the tutorials, the manual, and Flytandem's videos explain. I never, ever have a problem with it in sun orbit, or from the ground for that matter. The only time I ever have a problem with it is in orbit and it almost always comes from planning a plane change, and using the bullseye, of course. My hopes, when I started using transx, was that it could do the plane changes during ejection. But, as you stated, just set it in prograde with the autopilot - that, in itself, eliminates the need for transx until escape. I can do prograde ap without transx.

And, that's what I had deduced, that bullseye view is a waste of time in orbit, and therefore transx is NOT capable of off-plane transfers directly from orbit, at least not easily. I had hoped by this post that someone would tell me what I was doing wrong rather than confirming what I had already deduced: It's a waste of time. The off-plane transfer has to happen either at liftoff or after escape. Otherwise, the plane change will have to occur while in orbit before ejection, not during. Both you and Flytandem have confirmed this.

However, I had watched several tutorials centered around the "eject orientation" in transx, and thought that I might be able to use it to eject if already in parking orbit out of plane - another one of my experiments. However, this doesn't seem to be the case, as confirmed by Flytandem and yourself, and it is just best to initiate the plane change and use ejection orientation during launch, which is easy enough to do. And that was my primary issue. So, my suspicions are confirmed via this thread: A) tranx can't do off-plane transfers in every situation. B) Certain functions of transx can't or shouldn't be used in orbit.

Now one might ask why not just do this from launch? Simple. I'm using a spacecraft that is a deep space craft and not suitable for landing on the surface of planets. Therefore, the ability to do an off-plane transfer from orbit was enticing to me. However, through this thread and experimentation, I've learned that Transx is not the solution, and it may be impracticable to do any way.

So, I'm back to square one. Eject from orbit, then plan. Otherwise, I'm wasting time.
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Old 02-01-2011, 08:38 PM   #25
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I'm so confused.

---------- Post added at 12:38 PM ---------- Previous post was at 12:29 PM ----------

don't confuse inefficiency with impossibility. transx can be used to plan any direction and strength of speed change at any time, including doing plane changes. if you wish to combine a plane change into an eject burn as a single burn that's fine, you are best to do it by means of a maneuver, not as a plan because the plan only tells you that you are out of plane and requires you to fix that first. not sure what you mean by target not working. it is always used in maneuver and never used outside of maneuver.
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Old 02-01-2011, 09:18 PM   #26
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Originally Posted by flytandem View Post
 I'm so confused.

---------- Post added at 12:38 PM ---------- Previous post was at 12:29 PM ----------

don't confuse inefficiency with impossibility. transx can be used to plan any direction and strength of speed change at any time, including doing plane changes. if you wish to combine a plane change into an eject burn as a single burn that's fine, you are best to do it by means of a maneuver, not as a plan because the plan only tells you that you are out of plane and requires you to fix that first. not sure what you mean by target not working. it is always used in maneuver and never used outside of maneuver.

Right. Which is what I found. A plane change in orbit is best done first, before planning. I can plan the plane changes no problem. But, in orbit, if I try to plan via transx while in orbit, then the maneuver mode many times will put point the bullseye down into the surface or into a retrograde direction. That usually happens when I try to add plane change velocity as part of the plan. I'm hoping I'm just doing something wrong, but I am experimenting here.

I tend to agree with Mr Mxyzptlk that the maneuver mode bullseye view shouldn't be used during ejection. It was a fun experiment, to say the least, as was trying to use the ejection orientation out of plane while in orbit. Not necessarily impossible, but as you said, inefficient, and in my opinion, a royal pain in the rear.

The bullseye, however, does work like a charm as long as I don't do it in orbit. Maybe I'm just adding too much plane change velocity, whereby Tranx wants to do the plane change by a retrograde burn, flipping the orbit. I played with this some around the sun, retrograding until the orbit flipped. (unlimited fuel on, of course) :D Retrograde then becomes prograde and your new orbit is 180 degrees opposite your old orbit, reversing your direction.

I love experimenting with Orbiter, trying new things, and using utilities to perform tasks they weren't necessarily intended to do. It's part of what makes it fun.
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Old 02-01-2011, 09:56 PM   #27
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@cessnapilot and @Mister Mxyzptlk;

When you want to make interplanetary voyages, try not to just "picture" your orbit in relation to the Earth... try to picture it, in relation to the Sun.

As far as the Earth is concerned, you're going around it in a nice circular/elliptical orbit.

But, from the Sun's perspective, you're look like you're making S-turns! As you orbit the Earth; Earth moves in the prograde direction, relative to the Sun. So you're constantly moving "ahead" and your orientation-relative to the Sun- is constantly changing.
(hope this crude illustration helps)






I understand that picturing it in 4D (3D+time) is difficult... but if you manage to do it, the whole solar system and the orbital mechanics that govern it, will "open-up" like a flower for you.

I'm currently working on an illustrated pamplet, that shows these things in 3D+time.
I know, that different minds think in different ways, (this next vid shows an excellent example):




But i hope to be able- at least - to share with you, what goes on on my mind, when i'm thinking of orbits, and what can be done with them.

Have fun, happy orbiting!
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Old 02-01-2011, 10:17 PM   #28
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Originally Posted by cessnapilot View Post
 Right. Which is what I found. A plane change in orbit is best done first, before planning. I can plan the plane changes no problem. But, in orbit, if I try to plan via transx while in orbit, then the maneuver mode many times will put point the bullseye down into the surface or into a retrograde direction.
I wonder if you are doing the maneuver at the correct time (date). Please do something like what you describe and make a save and post the scenario.
Quote:


That usually happens when I try to add plane change velocity as part of the plan. I'm hoping I'm just doing something wrong, but I am experimenting here.
see above
Quote:

I tend to agree with Mr Mxyzptlk that the maneuver mode bullseye view shouldn't be used during ejection. It was a fun experiment, to say the least, as was trying to use the ejection orientation out of plane while in orbit. Not necessarily impossible, but as you said, inefficient, and in my opinion, a royal pain in the rear.
when leaving Earth I almost always use the plan just to get a proper parking orbit and date of ejection burn plus estimated burn amount. Then I set up a maneuver using the information from then Plan and then kill the plan with eject done via the maneuver and target.
Quote:


The bullseye, however, does work like a charm as long as I don't do it in orbit.
has worked like a charm in something like 5000 out of the last 5000 times I've used it
Quote:
Maybe I'm just adding too much plane change velocity, whereby Tranx wants to do the plane change by a retrograde burn, flipping the orbit.
another case of me wanting to see a scenario
Quote:
I played with this some around the sun, retrograding until the orbit flipped. (unlimited fuel on, of course) :D Retrograde then becomes prograde and your new orbit is 180 degrees opposite your old orbit, reversing your direction.

I love experimenting with Orbiter, trying new things, and using utilities to perform tasks they weren't necessarily intended to do. It's part of what makes it fun.
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Old 02-01-2011, 10:38 PM   #29
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Hmmm... Funny, I had always pictured figure 8's when thinking about an orbital path along the sun. Again, thinking of things in different ways. Great video.

I love mind challenges... Ever tried to figure out a tesseract in your head? That'll keep you awake for hours.

---------- Post added at 10:38 PM ---------- Previous post was at 10:23 PM ----------

Quote:
Originally Posted by flytandem View Post
 I wonder if you are doing the maneuver at the correct time (date). Please do something like what you describe and make a save and post the scenario.
see abovewhen leaving Earth I almost always use the plan just to get a proper parking orbit and date of ejection burn plus estimated burn amount. Then I set up a maneuver using the information from then Plan and then kill the plan with eject done via the maneuver and target.has worked like a charm in something like 5000 out of the last 5000 times I've used itanother case of me wanting to see a scenario

Hmmmm.... The right time. Now that is a very good possibility. I never really think about what "time" to eject other than the timer countdown based on the date I enter in transx. I will set one up tonight and post a screenshot plus the parameters I use for planning.

I'm thinking that maybe I'm doing something wrong with plane change, or the wrong time or a combination of both. I mean, if you've done it numerous times, then it is possible. And, even though transx shows me encountering the planet within say a few hundred thousand kilometers, I may be over adjusting something during planning that sets me into a retrograde direction. Oh, and it's not ever exactly retrograde. For example, it may want me to rotate 120 degrees left of prograde.

And, when I launch, I will use the plan, or at least MapMFD or LaunchMFD to get a proper parking orbit as well. It's just starting from orbit that has me baffled, when the ejection orientation won't line up, or when Transx wants to send me into the side of the planet.
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Old 02-01-2011, 10:50 PM   #30
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Quote:
Ever tried to figure out a tesseract in your head? That'll keep you awake for hours.

You mean something like this?
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