Orbiter - Space flight simulation

[Irokesengranate]

Ok, so about a week ago I came across this: http://orbit.medphys.ucl.ac.uk/home.php

I know its more of a simulator, but it is a piece of interactive software that you run on your computer for entertainment, so IMO it qualifies as a game (hence me posting on the gaming board).

The program claims to offer a fairly realistic simulation of spaceflight based on real (newtonian) physics. While I,´m not an astrophysicist (yet), it certainly feels like the simulation of physics is accurate and powerful.

The first few times I ran the program I felt lucky when I was able to reach a stable orbit (with one of the fictional vessels), two days later I was able to ascend to and dock at the ISS, and now I am flying forth and back between Earth and Moon on a regular basis . I,´m definitely hooked and the more I play it (and learn how to do things) the more fun it is.

Anyone interested in spaceflight, I highly recommend you check it out (its free). After a while of helplessly clicking around and being confused by all the numbers the instruments throw at you, it really gets a lot of fun.

Also, is there anyone on the forums who knows enough about the subject to say anything on how realistic it actually is?

 

[RigelKentaurusA]

I'll add my voice of recommendatiom, too. Great programme to learn orbital mechanics and have fun doing it.

Try building a space station in orbit of the Moon by hauling various parts (though granted, there's not a lot to work with in the default version). That can be fun.

 

[Irokesengranate]

A space station orbiting orbiting the Moon? That does sound interesting.
Are there any add-ons you can recommend in particular? I already got the invaluable IMFD, but nothing else really.

 

[RigelKentaurusA]

All the addons for space station building didn't work for me. I suspect I didn't install them properly.

But Orbiter comes with a sort of edit mode where you can tell it to spawn various default items (Shuttle, ISS, Mir, a couple space station blocks, nothing spectacular). I couldn't tell you from memory what menu it is in. The major problem I had going to the moon with two vehicles docked together was the mass was distributed weirdly so firing the main engines would exert a torque on the stack. I figure there's probably some way to counter this but I didn't figure it out, and ended up just burning the RCS to counter for it.

The default Orbiter has a 2001 Space Odyssey type rotating station already around the Moon in a fairly high orbit. You can find it with your computer's navigation menu, selecting moon, selecting the orbiting bodies, or something like that.

 

[AdmiralPeacock]

Orbiter revealed to me that I should never ever ever ever be at the wheel of the space shuttle - those trained space chimps would be preferable.

 

[Duvelthehobbit666]

Seems cool. I'll download it when done with exams in 2 weeks.

 

[Irokesengranate]

Argh, why did you tell me about the rotating station? That thing is docking HELL!

 

[Balstrome]

Argh, why did you tell me about the rotating station? That thing is docking HELL!

member, they may not be able to hear you scream in space, but your neighbours can hear you from your room.

 

[RigelKentaurusA]

Argh, why did you tell me about the rotating station? That thing is docking HELL!

Yeah I never successfully docked to it, but I don't think you have to angle yourself properly. I've docked to Mir and ISS in all sorts of angles and it re-aligned me once I was "docked."

 

[Irokesengranate]

I know that, but I wanted to do it properly to add some challenge to it, and after all, it,´s a simulator, why play it when you plan on 'exploiting' missing realism-features .
I actually made it on my first attempt, but there was panic and swearing involved. And some frantic course corrections the last second before the dock, because the light made it near impossible to see some of the instruments...

Now excuse my while I plan a transfer to Saturn for a school project, preferably with a slingshot involved somewhere... somehow...

 

[australopithecus]

This thread made me download the game. Dammit, I'm confused. Never let me near any type of space vehicle.

 

[RigelKentaurusA]

Orbital mechanics isn't terribly intuitive.

Consider a circular orbit. Your velocity is the same at all points in the orbit. A prograde burn will push you in the direction of your velocity vector (like hitting the accelerator in a car). A retrograde burn will push you against the direction of your burn. If you aren't yet sure how to tell where your velocity vector or negative velocity vector is, you can get a reasonable guesstimate by just looking at the direction Earth appears to rotate below you. The "apoapsis" is the point of your orbit where you are farthest from the orbited body, and the "periapsis" is where you're closest to the orbited body. The ascending node is the point of your orbit where you cross the "equator" of the orbited body, heading north, and the descending node is where you cross the "equator" of the orbited body, heading south.

Prograde and retrograde burns raise and lower (respectively) the altitude of the opposite side of your orbit. If I'm in a polar orbit, and I do a prograde burn over the north pole, my orbit will deviate from circular and become more eccentric, raising my altitude over the south pole. Similarly, if I perform a retrograde burn over the north pole, by the time I get over the south pole, my altitude will be lower.

Altitude and orbital velocity are more or less inversely proportional, leading to a somewhat confusing fact: If you accelerate, you'll increase your orbital velocity, but as you gain altitude, your velocity will decline. So if you want to lengthen your orbital period, you need to accelerate.

Your computer has a menu that shows you your orbit, along with a circle denoting where the surface of Earth is. You can toy around with prograde or retrograde burns to see how it adjusts your orbit.

Consider a circular, polar orbit. A spacecraft over the north pole performs a prograde burn, raising its south polar altitude by several hundred km. The orbit is now eccentric. After arriving over the south pole, another prograde burn is performed to raise the north polar altitude up to the same height as the south polar altitude. The orbit has returned to circular, but with a higher altitude, slower orbital velocity, and longer orbital period. This is a "homann transfer."

You can get to the Moon by performing such a large prograde burn that your altitude on the other side of the orbit is out toward the orbit of the Moon. If you time the burn right, you'll reach that apoapsis right about the time where the Moon is nearby. The moon's gravity will become a dominant acting force on your spacecraft, so you'll have the opportunity to perform a burn to put you into Lunar orbit. Exactly what burn is required depends on your approach trajectory, but it's typically a retrograde burn to slow down so that the Moon can capture you.

When leaving Earth for the Moon, consider your orbital inclination. Prograde and retrograde burns do not affect your orbital inclination. If your inclination is equal or similar to the Moon's, you're in a perfect orbit to reach the Moon.

Otherwise, you'll have just two windows where you can reach the Moon without expending a billion fuel. If it's unavoidable, you may want to adjust your inclination while in Earth orbit to align it to the inclination of the Moon's orbit by firing normal to the plane of your orbit. e.g. if I'm in a prograde orbit inclined 50 degrees to the equator, and I want to get into an equatorial orbit, I will burn perpendicular to the orbital plane towards the north when at the ascending node and perpendicular to the orbital plane towards the south when at the descending node. It may take several orbits to do this, it's not a terribly efficient use of fuel, but it beats ending up several tens of thousands of km away from the Moon after you reach the apopsis of your trans-lunar burn.

 

[australopithecus]

My planned trip to the moon ended with me heading towards the sun

*Edit*

However the second time around was far more successful

 

[Irokesengranate]

Flying to the moon in Orbiter isn,´t really that hard using the 'align planes' and the 'transfer' MFD. First align your inclination with the moon, then in the transfer program press HTO and adjust Dv and Time of ejection until the transfer works for you. when you reach the moon, do a retrograde burn for insertion and tada, you,´re there. There will probably be course corrections required while travelling, though.
The hard part is actually landing on the moon, i.e. 'collapse' your orbit so you reach the desired landing pad and decelerating while descending so you don,´t smash into the ground with 1200 m/s. I have yet to succesful land at Brighton Beach...

 

[RigelKentaurusA]

Yeah, Landing is definitely the hard part. I made a few soft landings on the Moon but nowhere near any specific targets.

 

[Irokesengranate]

Yay! Succesful landing on Titan . Did come dangerously close to Saturn,´s rings, but luckily they have no collision model.

 

[RigelKentaurusA]

Yay! Succesful landing on Titan .

No achievement points for you. Landing on Titan is epic easy :lol: (same is true of Venus)

 

[Irokesengranate]

No achievement points for you. Landing on Titan is epic easy :lol: (same is true of Venus)

Awww... . Seriously, I only did it for a school project to show some of the most basic orbital maneuvers during the flight to somewhere interesting (at least more interesting than Luna). Still, it,´s the furthest I,´ve travelled from Earth yet (not that I,´ve tried going any further).

 

[australopithecus]

I cannot reach anything further than the moon, that is to say I can align with the other planets but I cannot target on them to transfer. What am I doing wrong?

 

[)O( Hytegia )O(]

I cannot reach anything further than the moon, that is to say I can align with the other planets but I cannot target on them to transfer. What am I doing wrong?

I've yet to play the game myself - I'm currently on watch.
However, it might have something to do with the inability to change course directions due to current heading, or that after the moon you have to be forced to make manual shots (for added difficulty).
Try plotting your course more ahead of time.