New Release IMFD Full Manual

[Tommy]

I've never tried it, but I believe Target Intercept can be used for a KSC to ISS flight, even an offplane Direct Ascent. However, if the RInc is to high you'll never be able to rendevous due to excessive RVel.

 

[markl316]

I've never tried it, but I believe Target Intercept can be used for a KSC to ISS flight, even an offplane Direct Ascent. However, if the RInc is to high you'll never be able to rendevous due to excessive RVel.

Correct, as I stated in the manual, IMFD will get you to intercept the target at a point that's in its plane, so you can have an EIn of zero and an RIn of 45. I'll experiment.

 

[Arthur Dent]

Thanks for the great manual! And many thanks for the even greater Moon to Earth tutorial. That's a thing I eagerly anticipated over the last years.

I went through the tutorial and failed only twice because I didn't read careful enough (I entered "127.8" instead of "127.8k" and once I didn't do the reentry upside down).

It was great fun, though! I ended up being closer to White Sands than Cape Canaveral, but that's because I was aerobraking a bit too much.

Thanks a lot!

 

[markl316]

Thanks for the great manual! And many thanks for the even greater Moon to Earth tutorial. That's a thing I eagerly anticipated over the last years.

I went through the tutorial and failed only twice because I didn't read careful enough (I entered "127.8" instead of "127.8k" and once I didn't do the reentry upside down).

It was great fun, though! I ended up being closer to White Sands than Cape Canaveral, but that's because I was aerobraking a bit too much.

Thanks a lot!

The aerobraking is not as much as you think--don't exceed 1g. If you stay at around 68km until you hit 7500 m/s that should be good.

 

[Arthur Dent]

It was quite difficult to take a look at all these numbers at the same time. Thats why I ended up aerobraking at around 65km where the atmosphere is a bit denser so I decelerated too fast. I think if I tried once more, I might be able to nail it to the runway (well, at least I will end up closer to the cape )

 

[Tommy]

If you are using AerobrakeMFD you can extend the glide quite a ways after rolling upright. It may lead to skipping, but that's fine if it gets you where you're going.

 

[Arthur Dent]

Yippie! 'Gear touchdown at 4.232 m/s'!!! What a beautiful night at the cape! My first successful night landing (and my first successfull reentry and landing at a target base with the XR2) ever! Man, that's a rewarding feeling!

And my first successful return from moon!

Thanks for your help and your excellent tutorial!

 

[pattersoncr]

Does anyone have suggestions for making orbit eject burns with large/low-thrust craft (I'm using Descartes to go to Mars it produces 2-3m/s2).
What I ended up doing was burning into an elliptical orbit at the point indicated by the Orbit Eject program then doing the actual eject burn on the following orbit.

 

[Tommy]

That's the way I would do it, just be sure you start soon enough - once you raise the Ap that much you'll have a fairly long period. If you don't start soon enough, you'll have missed your window by the time you get back to the Pe. Ideally, you would arrange it so that you hit your Pe right about when TEj hits zero, so I'd say when raising your Ap, stop when your period = the TEj, minus a few minutes.

 

[Oceanic]

i thank you so much for your time and effort you put into this manual!!

i found a weird problem with the #7--Earth to Jupiter to Saturn playback, the radiator didn't deploy and the crew and the ship died. it could be a problem on my part since my laptop is not that young anymore. the strangest thing is that it worked the first time but not the second and third time i ran the playback.

for the time being i changed the CoolantHeatingRate to 2 (off) in the XR2 config

to those that have problems with the earth to mars or moon to earth playbacks, here is a "fix" that works for me.

open the record dialog, uncheck play at recorded speed, slow down time to x1, open the capera dialog and set the camera once to earth (or mars) so orbiter can load the textures in advance, go back to your ship and to the recorded speed and enjoy the playbacks on your vintage hardware

 

[Tommy]

Nice tip, that's going to come in handy on my old piece of outdated technology!

 

[Greybeard]

Great manual! Thanks to all involved. Now I sort of know what I'm doing (almost!).

 

[jedidia]

say, maybe someone can tell me this: I flew from saturn Orbit to titan yesterday, and everything went perfectly fine. Just the orbit insertion programm would not give me any solution. I couldn't even switch from eccentricity to apoapsis, nor could I change the target from ecliptic to equator. Reference was titan, and I was in its SOI. I used the standard Orbit MFD and got into orbit without much hassel, but IMFD orbit insert just didn't work (neither 5.3 nor 4.2).

 

[Kveldulf]

say, maybe someone can tell me this: I flew from saturn Orbit to titan yesterday, and everything went perfectly fine. Just the orbit insertion programm would not give me any solution. I couldn't even switch from eccentricity to apoapsis, nor could I change the target from ecliptic to equator. Reference was titan, and I was in its SOI. I used the standard Orbit MFD and got into orbit without much hassel, but IMFD orbit insert just didn't work (neither 5.3 nor 4.2).

What about Orbit Insert didn't work? Did auto-burn not work, or was the program not giving you a consistant solution (I've had my Orbit Insert "flash" between several solutions, rendering auto-burn useless). In times like that, Orbit MFD is probably your best bet.

Dumb question, but your Orbit Insert was configured correctly, right? It should be REF Titan

 

[markl316]

Yes, the flashing between several solutions is a problem sometimes. As stated in the do's and dont's, IMFD will not work perfectly 100% of the time. Sometimes that happens to me, it happens to everybody. As you get closer to the planet, it may or may not get better. This will happen maybe 1 in every 20 flights.

jedidia, you said "neither 5.3 or 4.2" worked. I think you probably meant 4.2.1 on that last one, just wanted to be sure.

I don't know about that radiator thing (I tested it on newer hardware so it may be a problem). I like both those solutions that oceanic suggested--very nice, and they should work both for the radiator and the freezing. Also, for the freezing, another way is to turn down the max patch resolution in the orbiter launchpad (under visual effects I believe). It doesn't matter how it looks during a playback, but you'll want it to look nice when you're flying there on your own

 

[thammond]

First off thanks for this manual/tutorial. I have learned a lot already.

Running palyback #2, Mars to Phobos, on my own got me to thinking about a few things I'm confused about.

In the playback, you advanced time until EIN = 0 before liftoff which makes sense to me. What confused me is the TIME which should be the optimal launch time continues to increase, why? Is TIME value not relavent to Lunar Off-Plane mode? Also what is TIn and TEP on the Surface Launch Program? I could not find any reference to them in any of the manuals.

After I had launched and established a parking orbit, I set up a target intercept plan but used the steps you have listed in the Target Intercept Program section of the manual to determine TIn and TEj instead of the values suggested in the playback. When I hit AB, it fired me back into Mars. So I'm not sure if I did something wrong or ran into a glitch.

 

[markl316]

thammond,
I'm sorry for taking so long to reply. I just started college at Georgia Tech, and I've been swamped with homework. I'll have time to look at your issues tonight.

Mark

EDIT: Here's the answer to your first question. The TIME item tries to display the optimal time to launch, I believe for relative inclination and NOT EIn, but I'm not sure. Anyways, with an Earth to Moon flight, since the Moon's orbit is inclined 23 degrees to the equator, you have two "optimum" launch times per day. With Phobos, however, it's inclination is zero (or so close to zero that it can be treated as zero). So there really is no "optimum launch time" because no matter what, relative inclination will be your latitude. But EIn will hit zero twice a day, which is when you launch. As a general rule, EIn being zero is more important than TIME being zero. If they're both zero at the same time, great, but if not, always go with EIn.

As for TIn and TEP in the Surface Launch Program, those may be typos, and I'll have more time tonight to look into those.

Question 2: That may be a bug. Did you try using Burn Vector View to complete the burn? If that still crashes you into Mars, use the steps from the playback instead of the steps from the Target Intercept page, and tell me if that works.

Mark

 

[Tommy]

After I had launched and established a parking orbit, I set up a target intercept plan but used the steps you have listed in the Target Intercept Program section of the manual to determine TIn and TEj instead of the values suggested in the playback. When I hit AB, it fired me back into Mars. So I'm not sure if I did something wrong or ran into a glitch.

There's kind of a flaw in the method used in that tutorial. It will work sometimes, but it all depends on where you are in your orbit when TEj hits zero. Target Intercept will have it's source set to Mars, so Target Intercept is ploting a course from the center of Mars to the center of Phobos. Target Intercept will have no idea where you actually are. Even if you set the source to self (actually, I don't think you can get a burn vector with self as target while within a body's SOI) it doesn't understand that you are in orbit. It will attempt to place your ship on a course from where it is RIGHT NOW to the target, even if that course will take you through the planet.

Transfer burns should not be made with Target Intercept, only correction burns after you leave a planet's SOI. Transfer burns should be made with Orbit Eject (or Slingshot, in some cases) set to course. Set the TEj in Orbit Eject to it's minimum dV, as close to the TEj in Target Intercept as possible - within an orbit or two is fine. This ensures an efficient burn (ie - close to prograde) and ensures that you miss your starting planet.

 

[thammond]

There's kind of a flaw in the method used in that tutorial. It will work sometimes, but it all depends on where you are in your orbit when TEj hits zero. Target Intercept will have it's source set to Mars, so Target Intercept is ploting a course from the center of Mars to the center of Phobos. Target Intercept will have no idea where you actually are. Even if you set the source to self (actually, I don't think you can get a burn vector with self as target while within a body's SOI) it doesn't understand that you are in orbit. It will attempt to place your ship on a course from where it is RIGHT NOW to the target, even if that course will take you through the planet.

Transfer burns should not be made with Target Intercept, only correction burns after you leave a planet's SOI. Transfer burns should be made with Orbit Eject (or Slingshot, in some cases) set to course. Set the TEj in Orbit Eject to it's minimum dV, as close to the TEj in Target Intercept as possible - within an orbit or two is fine. This ensures an efficient burn (ie - close to prograde) and ensures that you miss your starting planet.

Thanks for the info. I was wondering if it was a possibility that a solution could be found that wouls result with a burn vector through a planet.

---------- Post added at 06:28 AM ---------- Previous post was at 06:26 AM ----------

thammond,
I'm sorry for taking so long to reply. I just started college at Georgia Tech, and I've been swamped with homework. I'll have time to look at your issues tonight.

Mark

EDIT: Here's the answer to your first question. The TIME item tries to display the optimal time to launch, I believe for relative inclination and NOT EIn, but I'm not sure. Anyways, with an Earth to Moon flight, since the Moon's orbit is inclined 23 degrees to the equator, you have two "optimum" launch times per day. With Phobos, however, it's inclination is zero (or so close to zero that it can be treated as zero). So there really is no "optimum launch time" because no matter what, relative inclination will be your latitude. But EIn will hit zero twice a day, which is when you launch. As a general rule, EIn being zero is more important than TIME being zero. If they're both zero at the same time, great, but if not, always go with EIn.

As for TIn and TEP in the Surface Launch Program, those may be typos, and I'll have more time tonight to look into those.

Question 2: That may be a bug. Did you try using Burn Vector View to complete the burn? If that still crashes you into Mars, use the steps from the playback instead of the steps from the Target Intercept page, and tell me if that works.

Mark

Yes I checked the burn vector during the autoburn and the crosshairs were grey and centered. I tried it again and everything worked well.

---------- Post added at 06:45 AM ---------- Previous post was at 06:28 AM ----------

OK I moved onto playback number 3 and have a question. I understand the theory and mechanics of setting up the target intercept to Callisto, so that progress! I'm struggeling a bit with the theory and mechanics of the surface launch.

The playback did not launch at the optimal time calculated in the surface launch program. I do not understand the reasoning stated in the playback as to why the launch was performed when it was and not at the optimal time. I tried to run it on my own but the optimal time for the surface launch did not make sense to me. The first time I tried, I time warped close to the TEj time in the target intercept plan before opening the surface launch program. However the surface launch optimal time was greater than the TEj in the target intercept plan. So I reran it again. This time I opened the surfaace launch program right away after setting up my target intercept plan. I lauched successfully at the optimal lauch time, but I still had a long time to go to TEj which did not seem right either.

So I'm struggeling with the whole concept of when to launch after setting up a target intercept.

 

[Tommy]

The reason he didn't wait is because Europa, like most moons, is tidally locked with it's parent planet. The same side of Europa always faces Jupiter.

Remember, the launch plane indicated by Surface Launch is not referenced to the body you are launching from, but referenced to the body selected as reference in Course. This means there really is no "best launch time". "Best launch time" is when you can launch at 90 degrees (and get the boost from rotational velocity) and be in plane with the intended transfer. On a tidally locked body, that doesn't happen.

When on a tidally locked body, just give yourself some time to TEj so you can get to the ejection point. 6400k was a good guess. As long as it's before TEj, pretty much any time is as good as another unless you want to try to figure out exactly how long it will take you to get from the ground to the ejection point, and that's not worth it. As long as you are on orbit when TEj hits zero you'll be close enough. Remember, the TEj in Orbit eject will likely be different than the one in Target Intercept, so it doesn't hurt to give youself at least one full parking orbit.

If you are on a planet or moon that isn't tide locked, assuming a suitable launch latitude, you should have one opportunity per local "day" (relative to it's parent body) that allows a 90 degree launch into the target plane. Your launch "window" ends when TEj in Orbit Eject reaches the time it takes to get into orbit + 1/2 of the ejection burn (just give yourself a good half hour to 40 minutes) and begins one rotational period (relative to the parent body) before that, so be real careful with time accel during this period and launch when the 90 degree heading becomes available.