Windows of Opportunity!?

[DocHoliday]

Yup, those 5 little proggies in IMFD are quite usefull. Plane change and Circularize and Match Velocity in particular.
Also you can enable an auto burn function in the IMFD config file and the computer will do everything on its own
regarding burn if you want it too. LAZEEEEE piloting, I say just a series of menuvers without tedious calculation or
seat of the pants flying

[AphelionHellion]

Freespace: I am too. I haven't figured out the iMFD transfer function yet  Doesn't seem to let me enter the target
and reference. Either that or I need to enter them on different lines. I'm not sure how that works.

Right now I'm on my way to Mars using good ol Transfer MFD and the DGIII. My little scheme is working perfectly
I'm using the minimum fuel reserve setting (ISS only) but I'm docked to a fuel orb. It's way too farking big and heavy -
very tough to maneuver using the thing. It's like driving the Vespucci with an asteroid on the front. And I need to
gimbal the engines and use RCS to keep straight when I burn.
But hey, it's got 35000 kilograms of fuel (I edited it from the original 6000, which is WAY too small considering how big
the tanks are)  
I COULD just cheat and use the DGIII fuel loading, which would let you suck unlimited fuel from the thing, but I'm using
fueltransfer for realism.

[freespace2dotcom]

Eh, I'd probably just use a default fuel setting if I needed more fuel. You know I never tried it, but I seem to
remember that tthe fuel needed to get to mars and the moon from earth are pretty similar.

Although the burn to get to mars is longer, you can aerobrake. so it's nearly identical. I remember reading that on
that redcolony.com once. So that would really be something to achive. going to mars on realistic fuel? hehe. how
much more realistic can you get?

[AphelionHellion]

Freespace: Sounds risky. I mean sure you can aerobrake, but most space missions have a safety margin (such as the
Apollo's free return trajectory and docked LEM. Apollo 13 showed the value of that sort of planning). So sure you could
use most of your fuel to make the transfer burn and then aerobrake when you get to Mars, but if you miss, then you'r
boned :titanic: And it's a tiny target to hit with the normal transfer MFD
A mission to Mars with a large enough craft to hold people would need a fair amount of fuel, probably more than a
realistically represented DG sized ship could hold. That's why I like the ISS fuel mode with fuel module idea.

Oh, I shoulda realized this before, but the Shuttle A works WAYYYYY better docked to a fuel module than the DGIII
(duh)  The docking port is precisely aligned with the center of gravity and engines, so there's no pitching when
you burn. And the Shuttle A is long enough that you can pitch and yaw fairly quickly (you get good leverage with the
rear RCS nozzles).
Now I'm on my way to Mars in one of those babies, with a smaller and more realistic fuel load in the fuelOrb and some
cargo on the Shuttle (instead of just fuel tanks).

[DocHoliday]

Freespace: You usually can't aerobrake with the DGIII. you get way to high levels of temp Unless you are happy
with low G forces and low deltaV

AH: You can actually USE DG3 with the fuelmodule??? It always CTDs for me, when I try to start pumping. The sounds
of both addons mess eachother up. Same with Shuttle-A2. How did you get it to work??

[AphelionHellion]

Doc: Which addon fuel module are you referring to? I'm using the StationBuilder addon's FuelOrb.

[freespace2dotcom]

Bah, technicalities I say!

Sure, I wouldn't try such a thing in real life, but I'm gonna try for it. Only problem is I'm at my parent's house right
now, so I can't test out orbiter without the thing going super slow... my super-'puter is not available, I was
tempted to lug the thing over just because I'm addicted to it..

It's not like I do a free-return when I go to the moon or anything anyway.

I really don't think that aerobraking would give you too much heat on an earth-to-mars trajectory IF your apoapsis is
almost right on mar's orbit, and you arrive there just as it does. Of course I realize that I probably lack the skills for
something so precise, but what the hell, I can try, can't I?

Stop being so pessimistic! If I think it's possible, surely it is, for it's not often I think something can be done.



Post Edited ( 06-28-04 03:06 )

[AphelionHellion]

Free: You're probably right Sometimes it's possible to take the "realism" thing a little too far. I doubt NASA would
bother with all the safety procedures if they were in our situation (ie no money or lives to lose).
Also if you don't have a fallback plan it motivates you to be more careful


Plus in this case you have plenty of time to adjust your trajectory on the way in. This might even be the perfect
situation in which to test out iMFD's aerobraking program...

How slow is the computer in question? You can always try it at lower resolution. I'm sure a lot of other Orbinauts (like
me ) are using less than state-of-the-art PCs.

*envious*  

[MattNW]

I really think TransX was easier to learn in it's earlier versions. Making the jump from the old TransX to the new one
isn't as hard as trying to figure out the present version from scratch. On top of that the older version had a great
step by step manual for a trip from Earth to Mars which would also work for any other planet or a planetary system
like Jupiter. The procedure hasn't changed but the interface has altered radically so many people find TransX hard to
learn when they haven't gotten used to the earlier version.

You are probably going to hate me for saying this but not long ago I taught an 11 year old how to use TransX but
that was with the use of visual aids (basketball, two baseballs and a couple loops of garden hose). There are actually
only a few variables to take into account when doing an interplanetary transfer. This is where I think the current
version of TransX makes it more difficult for the novice. In the past you manually selected the Major, Minor and Target
and adjustment of the variables was a totally different step in the planning process. It was real simple, Major was
the Sun or whatever planet your present location and target location was orbiting. Minor was the planet you were
starting from and Target was where you wanted to go. Next step was to adjust the variables. You added or
subtracted (in the case of going insystem) some prograde and then tweaked the Ejection Date until you got as close
as possible. Switch back and forth as much as needed between prograde velocity and Ejection Date to refine
everything and keep adjusting the sensitivity down. Once you were as close as possible or as needed you aimed the
ship forward and gave it the gas.

It's still the same way with the new TransX but the interface is a little different, some of the functions have been
integrated and the selection of Major, Minor are automated. What's needed is another clear concise tutorial like the
older versions enjoyed that lays out the process step by step with illustrations. Duncan has tried with the manual
that comes with the latest version of Orbiter but I don't think it goes into enough depth to get a beginner from the
know nothing state to Interplanetary Voyager like the old tutorial did. What he's done is fine if you were intimately
familiar with the older version but it's not geared to the total N00B to this instrument.

[AphelionHellion]

MattNW: You're exactly right
I think I have the opposite problem that some new Orbiteers have. I already have a pretty good grasp of terminology
and procedures and I already know the basic elements (inc,ecc,apd,ped,sma,an/dn etc). I just have major problems
with the MFD interface and in what order to enter what information. I single step-by-step procedure for, say, a
transfer to Mars with the current version of transX would be infinitely helpful. I betcha I could master transX in 5
minutes if I had such a thing.
Really this is the problem I have with a lot of otherwise very useful MFDs (such as iMFD). The user manual gives you a
nice list of which key combinations do what, but it doesn't give you an example scenario of how someone would enter
all the data and in what order and where and when. In that case a few paragraphs would be worth more than pages
and pages of highly precise background information

[DocHoliday]

Yup, I can also say, that the terminology shouldn't be a problem, but what is missing is the procedure. Which thing to
set first and what to adjust next. Because most of these variables are inter-dependant and you have a hard time
getting it right. I also have the problem of not understanding how the system works. In the case of IMFD the manual
actually gives you some background information (how data is exchanged between the different subprograms), with
transX for example I didn't know that whatever you set in the Cruise planner, you can execute with the help of the
Burn Monitor subprogram in the other MFD. Also I don't understand the difference between stage and maneuver. For
example the normal way to go about it is to set stages and then just follow them. BUT if you do, the crosshairs are
not available as a view in the transx. However you can program the same thing as a manuver and than you have the
crosshairs available. Unless there is also something else I misunderstodo about this.

Little stuff life that gets you pretty confused...

[freespace2dotcom]

MattNW wrote:
You are probably going to hate me for saying this but not long ago I taught an 11 year old how to use TransX...

You're right, I am going to hate you. Oh wait. I already do.

Seriously, I have been making some slow progress with transx. But since youmentioned that the earlier ones were
easier, I may just try to find them..

the computer in question from earlier was a 500 Mhz Celeron. P-O-S.
(piece of sh**)

Hell, I found out that the thing didn't even have a graphics card, it was an old office surplus with grappy built-in
graphics only for 2D. orbiter wouldn't even run. but thankfully, I'm back at my beloved war machine.

AphelionHellion wrote:
I already have a pretty good grasp of terminology
and procedures and I already know the basic elements (inc,ecc,apd,ped,sma,an/dn etc). I just have major problems
with the MFD interface and in what order to enter what information. I single step-by-step procedure for, say, a
transfer to Mars with the current version of transX would be infinitely helpful. I betcha I could master transX in 5
minutes if I had such a thing.

On that note, I've gotten around with the thing, but It's just downright unfriendly. I thought I had finally got it set up
for a transfer to the moon, but I was wrong.... I couldn't figure out how to adjust when I should burn.. I adjusted the
date, but I'm pretty sure it only gave me readings for where I'd be at that date if I was to burn at the current time
under the current settings I had put up. somebody help me! a tutorial like going to mars would be super-duper cool

But, eh, well, maybe not five minutes, but I'm pretty sure it'd be a super-huge help to me, too. ten minutes, tops.

[AphelionHellion]

Freespace: Well if you've got any of it down at all, Keep at it!
*envious*

Hey, you wouldn't want me to figure it out before you, wouldja? That'd just kill you wouldn't it?  
Heeheehee

[freespace2dotcom]

Well, no, but for your sake, if that happens, you'd better have long legs to run away very fast, 'cuz I'll chase you for a
very long time. (screaming profanities along the way)

[MattNW]

freespace2dotcom wrote:

Seriously, I have been making some slow progress with transx. But since you mentioned that the earlier ones were
easier, I may just try to find them..

Not really easier to use. The current version is much easier to use but the older versions were easier to learn.
What really helps also is the fantastic tutorial Duncan did for the older version of TransX. It gives a perfect button by
button description on how to go from Earth to Mars with pictures showing the displays. I got it printed out and bound
in a notebook with all my Orbiter documents and tabbed so I can find the section I need to reference in seconds.
Currently however the present version has only a TransX manual with a couple paragraphs that can work as an
actual tutorial. What TransX needs is another tutorial only just like the old one or maybe just the old tutorial updated
to show the new interface so people don't get confused by the difference in buttons and stages. The current TransX
manual tries to do this but the info is sandwiched in between all the descriptions of the buttons and advanced
functions and it's difficult for someone new to TransX and Orbiter to find the relevant information for a simple
interplanetary transfer.

[DocHoliday]

I agree totally. Mars trip with the old TransX was easy. In the current one, I can't even fix up a launch window..

Um... about that tutorial. Khm.. emm.. umm.. could you do that for us, MattNW?

[AphelionHellion]

Freespace: Well I'm good in a sprint, but after that I'll just hafta hide, katana in hand, waiting...  
>=)


As for the tutorial - Heck I'd make one for y'all (and put it on my website) if I actually knew how to use the durn thing. I
just like to have a very good grasp of something before I go making tutorials about it

[AphelionHellion]

Just for the record, the Jupiter launch window named above works great - I used it to make the trip to Jupiter (where
I'm currently flying the 4 different Vespucci rider ships to Jupiter's 4 different moons (in the 2101 universe, so there's a
single base on each one).
Nice thing about the Vespucci is that you don't need to get the launch window perfect - you can afford to
accelerate past a transfer orbit to fudge the intercept a bit. One thing I noticed (well, I knew it before, but this really
illustrated it) is that transfers to an outward target (say, from Earth to Jupiter or Io to Callisto) are easier to adjust for
toward the end than transfers to an inward target (ie mars to venus). This is obviously because you're moving slower
at apoapsis/aphelion and you don't need to burn as long to inject into your target orbit. The planet's gravity helps
when you're moving that slow, too.
Going from a high orbit down to Jupiter's moons, that's proving a little more challenging. You rendevous at periapsis
right when you're at the fast part of your orbit and it's easy to burn too late and end up in a very eliptical orbit with
Jupiter trying to pull you away from your target.  On Io, even when you're on the surface, your orbit MFD says that
Io has only a 70 percent gravitational influence on you (I have no idea how to phrase that, but you understand).
Anyway, I've already landed one ship, on Io (figured I'd leave a bit early on that one to make the longest trip first).
I was actually landing ship number 3 but then Orbiter crashed and I forgot to save

I wish orbiter had an autosave feature - like where it quicksaves every x minutes.

Anyone else here have any practice juggling ships? Challenging but fun! The MFD thing kinda chafes me, though, the
MFD staying the same no matter which ship you focus on, so you have to keep setting up transfer MFDs and such
again and again and again when you have 3 or 4 ships en route. I guess that's why I haven't seen many
simultaneous multiship missions on orbithangar


Ok now I'm just rambling. Sleep time!

[DocHoliday]

Yup, that does suck. Sometimes even that can make Orbiter crash I think. The advanced MFDs may take offense if you
change ships on them as the targets and reference planets may change and they end up doing some kind of division
by 0 or something trying to be useful

Still Jovian system scares the piss out of me. Everything so close, moons moving so fast, you can actually notice it,
gravitational forces so weak, you can overshoot very easily. The only serious attempt at that particual badlands I did
was trying to play out Dan's DG3 scenarios, with that stranded dg3. *shivers*

What are you using as rider ships?

[AphelionHellion]

Hehehe, funny, I like the Jovian system for those same reasons. For one thing the longest you ever have to wait in
order to line up to transfer between moons is a couple days or so, and it's usually just a few hours, Orbiter time. And you aren't in transit between bodies for weeks at a time either. It's kinda like a condensed mini solar system

True about those fast moons, though! In high time acceleration you can see them whizzing around Jupiter like race
cars. IIRC, Io has a period of only something like 15 hours(!) One cool thing about the 2101 addon (at least I think it's the 2101 addon that adds this) some of the moons have a thin atmosphere (Io and Ganymede I think). It's not enough to need to worry about burning up on reentry or anything, but it looks nice

The ships I'm using are: ShuttleA2 (on Io - longest trip, so it's in the tanker configuration)
ShuttleA (en route to Europa - one external tank)
pbSpaceBus (en route to Ganymede - its further out and has an atmosphere)
and the Pegasus (very) light transport to land on Callisto.
I actually really lucked out When I entered Jovian orbit, it turns out the next orbit I'll make (the Vespucci) is almost a
perfect rendevous with Callisto. The Pegasus having such little fuel capacity, this was a great coincidence



Post Edited ( 07-01-04 13:01 )

[DocHoliday]

Neat And you didn't have any problems with the thurst vectors of the Vespucci with your wide array of landers? I
mean, I even refuelled all of the dg3's to make them the same weight, to be on the safe side

Okay, I'll give Jupiter a try. I'm heading there anyway, following your footsteps. I guess I'll just have to wait till
weekend. Too busy ... And use Freespace's launch window you say?

Pegasus..? Is that the one Simonpro's sigi mentions? Where does one get it?

[AphelionHellion]

Doc: Well granted I had the ShuttleA and ShuttleA2 across from each other, and they're probably approximately the
same weight even with different cargo configurations - and the pbspacebus and pegasus are both smaller than the
shuttles so I docked them across from each other on the other 2 ports.

Still I doubt it's that big a deal - sorta like worrying that a 747 is going to fly in circles because a couple more
people are sitting on the left side than on the right  The Vespucci seems to be even heavier (!) than it looks.

One thing I'd reccomend - don't try for a perfect, efficient transfer orbit like you might for a trip to Mars - set it up with
a fair amount of extra deltaV so that when you intercept Jupiter you're still headed outbound. It uses a bit more fuel
but it's worth it - you'll get there faster I think I shaved at least a couple months off my trip that way

Also I started from an orbit about halfway to the moon, about 195million meters altitude. Had to burn some fuel to get
there from LEO, so I kinda cheated: I edited the scenario and refilled the tanks. I'll just imagine that that's where the
assembly yard was all along
Good luck on your trip! Hopefully the scoop works for you. It wouldn't work for me so I only have about 18 percent fuel
remaining on the Vespucci I think the reason for the bug may lie with my using the fuel management MFD to transfer
fuel between the mothership and the fuel modules that the shuttles are docked to. More Orbiter abuse on my part
If your scoop works you should get there with a full tank. With the extra speed (ie a more direct orbit as opposed to a
Hohmann transfer) you should have more than the necessary speed for most of the trip, if mine was any indication.

PS: Duh!!
I figured out why I lost some speed en route to Jupiter - I didn't mention it before because fortunately I was traveling
faster than I needed to and I was able to make adjustments to compensate... But there was a definate alteration in
my orbit. It's because I left the ramscoop on, and it must simulate the braking effect of accelerating the hydrogen you
collect. Even though I wasn't gaining any fuel, I had the thing on just in case
You know, using a magnetic ionizing scoop like that on a gassy planet (say, Jupiter) I bet you could slow down in a
hurry and without the hull heating of aerobraking. Of course it'd screw up the target planet's atmosphere
something awful, but there's no one living on Jupiter that I'm aware of
I'd think using that technique to arrive at earth though could cause something along the lines of the movie "The Day
After Tomorrow" at least on a continental scale.
Muhahahahahahahaha!!! *evil mad scientist*
Seriously though, I should've anticipated the braking effect. That's the primary criticism I've heard of the magnetic
ramscoop concept, that in reality it'd make an effective brake but not much else

[freespace2dotcom]

Hehe. I know that vespucci is massive. you can't do a normal reentry like with the DG because the friction generated
by the atmosphere does nothing. I'll try using that scoop on jupiter. very interesting... of course, the G's you receieve
while breaking would likely kill the crew if not tear the ship appart. I would say that I wish that the scoop and the
gravity emulation thingys weren't controlled by the same switch. I told you guys that my launch windows worked.
please tell me if you do find one that's a little too off and I'll fix it. I haven't too much experience with jupiter system
myself, but I did complete that mission scenario that came with the DG3.

I'll also get around to giving launch windows to get to earth from all the other planets when I get around to it. It'd be
nice to finally return to earth, wouldn't you say?

[MattNW]

DocHoliday wrote:
I agree totally. Mars trip with the old TransX was easy. In the current one, I can't even fix up a launch window..

Um... about that tutorial. Khm.. emm.. umm.. could you do that for us, MattNW?

I've thought about doing that but someone else would have to put the screenshots and text together to post it as a
webpage or a .pdf file. I don't have much more than the standard Wordpad on this machine. I use TransX a lot but
it's been ages since I've done a flight from the ground to another planet. Been using Vespucci and other large
transports more than anything and they require you to start from orbit. Got a big family reunion coming up later this
month but I'll see what I can work up right after that.

[AphelionHellion]

Freespace: I don't think Orbiter actually simulates the interaction between the scoop and a planet, I was just thinking
that in reality it'd probably be pretty darn impressive a transfer of energy


MattNW: I have all manner of web publishing and graphics tools sitting around on my hard drive gathering dust. If
you'll provide the text and a couple reference images, I bet I can handle everything else