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Author Topic: Need help to moon  (Read 33060 times)

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Offline freespace2dotcom

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Reply #50 - 14 June 2004, 11:31:14
I'm not sleeping! I'm studying, dammit! maybe I'll hunt down a scanner and show you how scary this stuff is! I have
finals in 2 and a half hours and my notes are scattered and scarse. I'm DOOMED! *freespace jumps out a window*


Oh, and moderator is also higher than living legend.



Offline DocHoliday

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Reply #51 - 14 June 2004, 11:50:01
Oops, didn't realize that. Good luck, you'll obviously need it :)


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"Mood is a matter of choice. I choose to have fun!" -Vidmarism No 15

Offline freespace2dotcom

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Reply #52 - 14 June 2004, 11:52:36
Thanks... I guess that sounded meaner than I intended, but I'm a little tense right now..



Offline DocHoliday

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Reply #53 - 14 June 2004, 11:54:57
*goodintentionally* maybe you should get offline and do what you can in the period left?


~~~

"Mood is a matter of choice. I choose to have fun!" -Vidmarism No 15

Offline freespace2dotcom

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Reply #54 - 14 June 2004, 12:07:47
Nah, I can't go any further that I have. I just have to leave for school earlier than I normally do and ask the local
smart guy in our class before class actually starts. the rest is up to that... some stuff just doesn't make sense to me..

like how can a circuit (which is "supposed" to be in resonance (where XC=XL)) not follow this stupid formula for
finding the resonance frequancy.  if I plug that same frequency in another two formulas, I'm supposed to get the
same answer, but I don't.... I can't figure that out... so... it's up to the amount of time I have before class to ask
questions to this smart guy (who makes everyone else look really bad on the tests....) I'm stuck at this point. I just
hope  I have enough time at school before class. that's where the last of my struggling is. It's funny though. it's not
that hard as you learn it in school, but when it comes time to use it in a test, it dissapears like that.... *snaps*

anyway, I'm super lucky because It's even an open-book test. we're not expected to memorize the formulas 'cuz
there's so damn many of them, but they figure that If you don't know how to do the stuff, having the book won't help
you anyway... I'm at the point where that's not entirely true... but I have about an hours' ride on the bus to review
before I actually get there, so no rush...



Offline AphelionHellion

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Reply #55 - 14 June 2004, 12:51:00
~Sending Freespace some positive universal knowledge vibes~

< [yellow]C[/yellow]arpe [yellow]N[/yellow]octem! >

Offline DanSteph

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Reply #56 - 14 June 2004, 13:20:30
Quote
DocHoliday wrote:
What's above living legend is up to dan. :) Only Admin is higher at the moment.

I can add some ranks if you want, but I don't know really what can fit here

"immortal legend" ?
"???"
"god" (sound a bit pompous a***)

Dan


Offline Simonpro

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Reply #57 - 14 June 2004, 13:21:58
Mr Spock should obviously be the highest level :turning:


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Offline DocHoliday

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Reply #58 - 14 June 2004, 13:35:36
Hehe, how about Buck Rogers -> Flash Gordon -> Mr. Spock -> Luke Skywalker -> ROOT :) -> All your base are belong
to us :wor:


~~~

"Mood is a matter of choice. I choose to have fun!" -Vidmarism No 15

Offline Simonpro

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Reply #59 - 14 June 2004, 13:37:25
Darth vader is obviously betrter than luke :p


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Offline Shmi

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Reply #60 - 14 June 2004, 15:05:04
I hope Freespace did OK :top:

- I always found that anything I tried to revise <24 hours before the exam wasn't absorbed well enough to be of
much use.  It was much better to be well rested and calm(ish).  Mind you, I can't talk, I did dreadfully on the first
paper of my finals because I was so nervous.  (We had to take all our papers on 3 years work over 1 week you
couldn't get credits as you went along).



Offline Atom

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Reply #61 - 14 June 2004, 15:53:49
Atom should be the top rank, seeing as it is obvious that I beat Luke Skywalker, Darth Vader, Buck Rogers and all
those other amaturs. Hehe.



Intel Pentium 4 630 3Ghz|1024mb 400mhz DDR RAM|ASUS P5P800-VM|Nvidia GeForce 6200 256mb|Creative Sound Blaster Pro Value!|Windows XP SP2

Offline DocHoliday

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Reply #62 - 14 June 2004, 16:21:43
But there is always:

FLASHHHH! aaaaaaah! FLASHHHH! aaaaaaa! :wor:

*for those of you freaks who saw the movie - me included * :)


~~~

"Mood is a matter of choice. I choose to have fun!" -Vidmarism No 15

Offline freespace2dotcom

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Reply #63 - 14 June 2004, 17:07:33
Ah.. thanks, shmi! however. I get the feeling that I either did really good, or REALLY stinkin' bad. I wno't know until
my grade comes in. either way, come this thursday, I get a three week vacation before summer term starts, and even
then I'm gonna take it easy with maybe 5-6 credit hours compared to the 15 I took this term and the 19 I took last. I
don't wanna burn out, don't ya know! :) about the particular equation I mentioned, my smart friend showed me what
the problem was, and it turned out that the equation I was using was correct, but my stupid calculator didn't group
the equation right.. to put it simply I put in 1+2x3, yet it seemed to spit out 1x3+2. very bad. a helpful parenthesis
corrected that. so I'm sure I got that particular question right. but... we'll see. That particular teacher didn't like giving
homework, which was nice, but I'm thinking that if he did give out some, my final grade wouldn't be effected so much
by this last exam. oooh, and I've got another equally hard one coming up tomorrow... this time, it's on digital logic
chips and their functions, not electric circuits. I'm too young for this! why did I sign up for it? ah.. well.. the only
way to get smarter is to do this stuff. I already knew more about computers than the average person. but now I
know computers count. the very rules that computers abide by. The only reeason why a computer is complex is
because there are billions of chips doing things, but they are billions of not so many different parts... doing identical
things, but since they do it together with the speed of electricity, they can seem to do anything. :)

Very fascinating stuff..

in any case, I hunted down a sample page.. one that covers a small partion of what I've been learning thus far. Isn't
it mumbo-jumbo? (unless you really look at it, but my brain kinda turns off after seeing all those numbers... That's not
to say that I don't know kirchoff's law now.. this is pretty basic compared to measuring voltage charging from a
capacitor over certain time references. As well as measuring impedance through capacitors and the like...:) That's not
fun at all..)

http://www.hokaar.org/Physics_Examples/Kirchh/kirchh.htm

Oh wait! We wanna talk about going to the MOON! not electronics!



Offline Shmi

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Reply #64 - 14 June 2004, 19:04:28
Quote
freespace wrote:

in any case, I hunted down a sample page.. one that covers a small partion of what I've been learning thus far

http://www.hokaar.org/Physics_Examples/Kirchh/kirchh.htm


It made my brain hurt just to skim-read it.  :???: I'm afraid my brain has lost too many brain cells since I had to deal
with that many equations.  Good luck with the next exam! ;)



Offline Simonpro

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Reply #65 - 14 June 2004, 19:13:13
I hated kirchoffs laws when i did them last year, they bored the pants off me.


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Offline DanSteph

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Reply #66 - 14 June 2004, 20:29:47
Quote
DocHoliday wrote:
But there is always:
FLASHHHH! aaaaaaah! FLASHHHH! aaaaaaa! :wor:


At first I tought that you took to much cookies from the Asteroid  Belt LOL :)
but now I remember this song from the movies... if I recall well it was a song
from Queen  (and for the younger people here NO I don't speak about the
mother Queen)






Post Edited ( 06-14-04 20:30 )


Offline Krytom

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Reply #67 - 14 June 2004, 21:11:17
Help :help:!

My mum's started singing Flash Gordon!!!!!!!!

Quote
... if I recall well it was a song
from Queen (and for the younger people here NO I don't speak about the
mother Queen

Queen Rock!!!! :wor:



Offline DocHoliday

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Reply #68 - 15 June 2004, 09:00:32
hehehhehe.. Yup, that was the one. Forgot it was Queen...

Queen Rock! Freddy Mercury was a genious despite all his vices :)

Cheers,


~~~

"Mood is a matter of choice. I choose to have fun!" -Vidmarism No 15

Offline freespace2dotcom

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Reply #69 - 15 June 2004, 09:13:12
Queen, as in "We are the champions" queen?

That song is cool.



Offline DocHoliday

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Reply #70 - 16 June 2004, 21:42:13
The same Queen :) Anyway Freespace sez:
Quote
Let's get talking about the MOON again, people!

So here is another promise kept:

For the record: You can get to the Moon with 33,7 %difference of fuel!!! That's 54,3% at start MINUS 20,6% at Pad 2,
Brighton Beach! Eat your hearts out!!! (again) :)

Now to back up my claims, here is how I did it, plus the photographic material to prove it :)

Take a standard DG3, 1 months O2&N2 reserve, Default (ISS&Moon) fuel reserve and Mark IV (260'000N) Engines,
Phoenix Industries skin (of course) :)

Load the ToTheMoon scenario that comes with IMFD. I am posting it here, so you don't have to bother ( left out the
MFD part in case you don't have IMFD, put in whatever you like). Leave the SH-01 in the scenario, it will be helpful:

------------
BEGIN_DESC
DeltaGlider ready for trans lunar injection.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51982.9703756366
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL-01
END_FOCUS

BEGIN_CAMERA
  TARGET GL-01
  MODE Cockpit
  FOV 50.00
END_CAMERA

BEGIN_SHIPS
ISS
  STATUS Orbiting Earth
  RPOS -5710655.54 3590118.47 93270.28
  RVEL 3848.900 6169.551 -2487.072
  AROT 30.00 0.00 50.00
  IDS 0:588 10 1:578 10 2:568 10
  XPDR 466
END
Mir
  STATUS Orbiting Earth
  RPOS -5066788.89 265788.15 4345713.93
  RVEL -5033.717 -357.649 -5847.488
  AROT 0.00 -45.00 90.00
  IDS 0:540 10 1:542 10 2:544 10
  XPDR 482
END
Luna-OB1:Wheel
  STATUS Orbiting Moon
  RPOS 948076.85 2028314.04 728.81
  RVEL -1340.387 626.551 0.333
  AROT 0.00 0.00 -152.60
  IDS 0:560 10 1:564 10
  XPDR 494
END
GL-01:DeltaGliderIII
  STATUS Orbiting Earth
  RPOS 2895576.91 -124396.12 -6490459.16
  RVEL 6822.118 -647.359 3051.514
  AROT -12.22 -65.95 12.14
  VROT -0.00 0.06 0.00
  RCSMODE 2
  PRPLEVEL 0:0.543 1:0.987
  NAVFREQ 0 0 0 0
  XPDR 0
  NOSECONE 0 0.0000
  GEAR 0 0.0000
  AIRLOCK 0 0.0000
END
SH-01:ShuttleA
  STATUS Landed Moon
  BASE Brighton Beach:1
  POS -33.4375000 41.1184067
  HEADING 0.00
  PRPLEVEL 0:1.000 1:1.000
  NAVFREQ 0 0
  XPDR 0
  PODANGLE 0.0000 0.0000
  DOCKSTATE 0 0.0000
  AIRLOCK 0 0.0000
END
END_SHIPS
------------

Okay, so you can either follow the tutorials that come with IMFD (Lesson 1 and Lesson 3) or use your favourite
navigation tool to set up your flight to the moon.

Pick your time and burn for moon, standard Hohmann transfer more or less. Aftre the burn and various adjustments I
had 37% fuel left.



After about 3-4 days, you should be close to the Moon and ready for your retro burn. Now if you use the IMFD, you
can follow the Lesson 3 tutorial and try to get your orbit to pass over Brighton Beach. You can probably do it manually
to but I didn't try that.

Perform your retro and circularize your orbit at about 380km. With IMFD that's easy, otherwise you'll have to fiddle
with forward/backward and outward/inward burn at some distance from the moon (30000km), to set your perigee to
about the right altitude. Now in my case, I was following the tutorial which guided me to a reverse orbit (clockwise) it
is not necessary, but the tutorial had a different plan for Moon landing, which I then didn't follow anyway. You can
adjust whether your orbit will be clock or counterclock-wise, by applying pro/retro burn at a fair distance from the
moon. Just watch the orbit display and see how to hyperbola changes.

Assuming you're in a circular orbit, now comes the tricky part. You have to to a "Direct Landing" (TM) :wor: also
known as Powered Descent Initiation (as they called it on Apollo Missions) :) which you do by lowering your periapsis
to 10km (Apollo did 20km I think), and position the periapsis point a few degrees ahead of the Brighton Beach base.
This means, that you will reach your minimum 10km a few hundred km before the base and this gives you a nice
buffer area, where you can reduce your horizontal velocity to zero and keep your vertical velocity around 0, without
burning too much fuel on Hover engines.

Now, you move your periapsis by appying prograde and retrograde RCS burns, anywhere on your orbit, but it's best
when you are 90degrees away from periapsis/apoapsis. Set the OrbitMFD target to SH-01. This will give you a visual
clue of where Brighton Beach is with relation to your orbit. You will notice as you burn pro/retrograde that the
Argument of Perigee (AgP) changes. Now, move the periapsis to something like this (just the position, the value of
AgP will vary) on the picture and burn retrograde at apoapsis to lower the periapsis to 10.000m (display 2 - DG3
panel). It only takes a few seconds.



Now hit PAUSE, keeping the DG3 retrograde and take out your calculator. We need to calculate when to start
braking, so that we reach the Brighton Beach, having low or no horizontal velocity left. We will burn retro, as the Main
engines are stronger. At this point they provide about 15-16m/s^2 acceleration. We need to determine what our
velocity near the perigee will be. The formula for orbital velocity in a CIRCULAR orbit is as follows (BEAR WITH ME, it's
easy):
Velocity= SquareRoot(Grav.Constant*MassOfMoon/((RadiusOfMoon+Altitude)*1000)). The data I used are:
Grav.C = 6.6E-11
MassOfMoon = 7,34766E+22
RadiusOfMoon = 1738 km
Altitude = 390 km
Now this gives you about 1517 m/s. As we are NOT in a circular orbit, you need to measure your velocity at apoasis,
just after the retro burn is complete. I measure about 1441 m/s. The speed at periapsis will be greater than 1517
m/s, but I was lazy and I just used a dumb logic off adding the difference I measure at apoapsis (hehe). 1517-
1441=76m/s. I calculated what speed I would have in a circular 10km orbit and got 1674 m/s. I added this difference
to the calculated 1674+76=1755 m/s. Now this dumb adding probably has some math roots somewhere, but I just
figured, that if you go slower at apoapsis, you need to as much faster at periapsis to make up the difference and
keep the orbital energy the same. Turns out the actual speed at periapsis was just about 1755 add or take a few
m/s. :)

Anyway, we now know how fast we'll go. We also know how fast the DG3 can decelerate. about 15 m/s every
second. So you calculate at what distance you will come to a halt = 1755/15=117 km. So you need to start braking
117km from Brigton to come to a halt over it. Now being a living legend, I applied my experience and figured that the
Dg3 engines will actually increase thrust as fuel is burned and Dg3 gets lighter, so you can actually start even later
than that, say 115. So I start the burn, then after a little while, I turn the DG3 level and engage the PRO200SPEC7
autohover mode so the DG3 will keep it's drop rate at a manageable level. Set it to -10m/s or so and wait for the
Main engines to get the burn finished. Set your radio frequency to that of the SH-01  (108.00) and you can actually
use the DOCKING HUG to help you get the relative speed down to zero in the right time, plus help you yaw the ship,
so you don't fly passed the base. Also use the base VOR frequency to guide yourself in.

At the end you should look like this. I actually got the speed down too fast (main engine's thrust increased way over
16m/s), hence the engines are off:



and like this :)



And my final stats:



Quesitons, class?


~~~

"Mood is a matter of choice. I choose to have fun!" -Vidmarism No 15

Offline freespace2dotcom

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Reply #71 - 16 June 2004, 22:03:46
AHH!! You have WinXP!  EVIL lies within your machine doc, you need to purge it at once! I too had a copy of XP, and it
bit me in spirit, very badly. It will regret the day it locked me out of my own computer because I reversed my cd drive
cables to experiment with something.

Anyways, Yeah, I can get to the moon with about that much fuel too, but I had to do it without the payload.
that's all the difference right there. Of course. I have always sucked at landings, and as such, I use up too much
fuel there no matter what technique I use. rest assured the very first multiplayer orbiter scenario I want to play will
be racing (and beating) you to the moon. but alas, you show me that I need to hone my skills more before I attempt
that to ensure victory.

Although I will mention one thing. you use more math than I do. I myself play orbiter because I think it's a good way
to pass the time. learning new concepts along the way sometimes. But if I have to break out a calculator for anything
other than interplanetary travel, I'm gonna be mad. calculators are reserved for WORK! not for play! that's why
orbiter is more fun than homework for me! anyway. I'm definately more of a "seat of your pants" kinda guy. no
planning, just reacting to numbers. for instance. in order to get back to earth from the moon, I just align my plane
with earth once in a circular lunar orbit, and the instant I can see earth come over the horizon, I turn on the thrusters
until eccentricity is about 1.5.

you can't get less mathematical than that. And I really wouldn't prefer it any other way.  :)



Offline DocHoliday

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Reply #72 - 16 June 2004, 22:31:09
Heh, I hear you. But I have been playing with Orbiter longer than you, and I don't resent calculators like that. I think
of them as extension of my limited brain, not the slavemasters :)

hehe anyway, XP used to suck, but it's okay now. Beats Win98 in most things, especially crashes, not to mention
Win2000. THAT WAS SLOOOOW....

Anyway, wish you told me you can do the moon trip well enough, I wouldn't go to the trouble, but hey, someone else
may find it useful.. I will try it with the payload too. A question though. WHERE is it in the DG? Dan said in the manual
that you can see it in the cockpit, but all I see is the 4 dumb faces of the pax.. i'd expect to see the cargo instead of
them...

Turns out that IMFD is a lot easier to use than TransX.. .:) As for the race to the Moon. My method may be more
efficient, but I bet you'd get there faster. Seat of the pants pilots are ALWAYS faster, but may not get there at all. Or
make a crater the size of Phobos along the way :) You know, the rabbit, turtle story.. kind of :)

Hehe, your way of going back to Earth sounds just about right. I do think that Apollo actually used a similar move :) I
suck at retro interplanetary orbit burns though.. be it getting from the moon back, or from Earth to Venus. I just don't
dig the logic :) How can you reduce the speed, without falling to Earth as you do and instead fly off to venus.. :) just
doesn't feel right. I tried it a few time, it works, but goes against my principles :) go figure..


~~~

"Mood is a matter of choice. I choose to have fun!" -Vidmarism No 15

Offline Simonpro

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Reply #73 - 16 June 2004, 22:54:18
v^2=mu(2/r-1/a)


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Offline DocHoliday

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Reply #74 - 17 June 2004, 08:35:41
Ah, that's the direct formula. Heh, wish I studied physics too :)


~~~

"Mood is a matter of choice. I choose to have fun!" -Vidmarism No 15