Orbiter
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| Going Prograde | |
Auteur: Seriphyn Status: Non-membre du forum | Date 10-02-2005 21:03 |
Long-time veteran, but I've been in and out of the game so much, I forgot everything. Previously, I learnt how to get into orbit then deorbit and ditch in the ocean. I'm having a problem with this manual. I quote.... "-Cut thrusters when your apoapsis distance reaches 6.731 -To enter a circular orbit, you need to perform a further burn at apoapsis. The apoapsis point should be on the opposite point of your orbit and should take 45 mins to reach. At apoapsis, press the 'Prograde' button..............." Is it asking me to go prograde as soon as I reach 6.731 and cut thrusters? Or is it asking me to hit apoapsis, cut thrusters, wait until ApT reaches 0 by waiting (because it always climbs) and THEN go prograde? The main problem is how the instruction is divided into 2 bulletpoints and not one, so I'm getting the impression they're done at seperate times. Thanks in advance. |
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| Re: Going Prograde | |
Auteur: Strogoff 728 Messages Status: Légende vivante  | Date 10-02-2005 22:24 |
Well. The first thing is to go up.. When you and the apoapsis is out of the earth's atmosphere, then you can cut all thrusters and power ... let's Newton do the job... When you reach apoapsis, to circularize your orbit so your periapsis is out of the atmosphere too, you need to burn PROGRADE, so First you put your spaceship prograde and then you put the power on. Between the time you switch off and the time you'll switch on the engine again... you can put your spaceship Prograde, retrograde, .... just have a look but don't switch on the engine ! Good travel.  |
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| Re: Going Prograde | |
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Auteur: Seriphyn Status: Non-membre du forum | Date 11-02-2005 19:17 |
Right, so when the the right point of that oval goes out of the grey ring (earth), I cut thrusters. THEN, when ApT reaches 0, I go prograde? |
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| Re: Going Prograde | |
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Auteur: Seriphyn Status: Non-membre du forum | Date 11-02-2005 19:23 |
<slaps head....hard> "When YOUR apoapsis distance reaches 6.731" D'oh! Its saying when the apoapsis reaches a DISTANCE and NOT when you reach it. Sorry, about double-post, can't edit my previous one. |
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| Re: Going Prograde | |
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Auteur: DocHoliday Www 2451 Messages Status: Légende vivante | Date 11-02-2005 21:28 |
Hi Seriphyn, did you get it done? The idea is this: - ideally, you would cutoff your engines once you reach your apoapsis (highest point in your orbit) and AT THE SAME time reach your desired orbital velocity (7.6 km/s or so depending on altitude of orbit). Since you need a lot of experience to time everything right, including the pitch angle at ascent, you will probably have to do it in two steps: 1. reach a comfortable altitude of something like 200km. You will probably have too little horizontal velocity and your periapsis will be below the Earth surface (6.378 km). So you need to raise your periapsis otherwise you will reenter something like 1/3 of orbit later.. 2. since your pitch was probably too high for too long, your apoapsis will be ahead of you. Which means, even after the engines are off, you are still climbing. So you need to circularize your orbit, by burning prograde at your apoapsis - (ApT=0, preferable some seconds before your reach it) because the burn is MOST efficient there - which will raise your periapsis to a similar altitude than apoapsis and you will have achieved orbit. That's it... If you're really skilled, use an autopilot or in some other way manage to achieve your orbital velocity at the same time as you reach your apoapsis (see ApT, when it is 0), this phase is not required. Try the DGIII autopilot and see how it does it's thing and you should get a very clear picture if my explanation seems unclear.. Cheers, Janez ~~~  Founder of GSI Creator of the Direct Ascent to ISS Maneuver & Scenario "Mood is a matter of choice. I choose to have fun!"[/i] -Vidmarism No 15 |
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| Re: Going Prograde | |
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Auteur: freespace2dotcom 2223 Messages Status: Légende vivante | Date 11-02-2005 22:10 |
hehe. Generally, it's not too hard to orbit.  just get high enough, and then start going sideways, with your nose pointing upward enough to cancel out gravity. eventually, your speed rises high enough that you no longer need to bother with it. (REAL orbiteers don't need fancy autopilot modes  ) |
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| Re: Going Prograde | |
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Auteur: DocHoliday Www 2451 Messages Status: Légende vivante | Date 11-02-2005 22:31 |
Agreed. BUT, if you fly manually, you need to know how it works At least that's what helped me.. simple trial and error isn't enough. Oh and it's Orbinauts ~~~ Founder of GSI Creator of the Direct Ascent to ISS Maneuver & Scenario "Mood is a matter of choice. I choose to have fun!"[/i] -Vidmarism No 15 |
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