Physics of Elite Dangerous

[peteuplink]

Heavy sarcasm.

A lot of planetary bodies in E: D can be orbited "properly", you simply have to pick bodies where your "maximum velocity" is not a concern.

Sure, its not N-body physics, but there is representation.

Your maximum velocity has no bearing on the orbital physics in Elite Dangerous. I've just recorded a video of myself in "orbit" around Enceladus (which is currently uploading I'll add it to this post when it's done).

The guy in the video above said that his speed was 172m/s and this was enough to achieve and orbit of 8.94km... Well, I was "orbiting" at my Cobras maximum speed, with full pips to engines and boost, and could easily hold 8.94km, but at a higher speed I should have been oribiting at a higher altitide (as you can see in this video increasing speed raises your AP, or apoapsis, which increases altitude https://www.youtube.com/watch?v=D7hmHoXGpi and in this video of Orbiter https://www.youtube.com/watch?v=g7flhlRV_Zs.) Also, just to see what happened, I throttled down and came to a complete stop, and my altitude held steady. If you could come to a dead stop in a true orbit, you'd plummet to the ground. I dropped to below 2km and performed the same actions, even turning off my thrusters, and got the same results.

Therefore, you are not truly orbiting in Elite Dangerous, you're simply flying around the planet at high altitude as you would if you were flying at low altitude. You can turn off the FA or your thrusters, but you're still just flying around the planet at a set speed, changing your velocity has no effect on your trajectory. It's not a true orbit.

Again, sorry.

Edit: video added

[video=youtube;G21UkDR2xY8]https://www.youtube.com/watch?v=G21UkDR2xY8[/video]

 

[CmdrJacks]

Orbits are just the balancing of force vectors (gravity and velocity) and so you could say that Elite has orbital mechanics in so far as Elite has gravity and speed, but this is a matter more of mathematics than of physics. Objects of different mass fall at different rates in the same gravity field in this game so what we have is not a realistic system. The fact that Sidewinders and Cobras are affected differently by gravity means that they will have different orbital velocities. You can completely forget about trying to deploy a cargo cannister into orbit, or a minefield. I don't know what the "gameplay" reasons are for this, I suspect there are none and it just isn't viewed as important by the devs. Sadly, FDev's rollercoaster game probably has more realistic physics than its spaceship game.

 

[peteuplink]

The fact that Sidewinders and Cobras are affected differently by gravity means that they will have different orbital velocities.

It's not even as complicated as that CmdrJacks. Your speed in ED is your absolute velocity and has no bearing on what you do in orbit. You could "orbit" in a sidewider or cobra, or any ship for that matter, at 1m/s if you wanted, because you're not really orbiting. It makes no difference if you're 30m above the surface or 8km above the surface, because you're simply flying around the planet not orbiting.

 

[Wylie28]

Your maximum velocity has no bearing on the orbital physics in Elite Dangerous. I've just recorded a video of myself in "orbit" around Enceladus (which is currently uploading I'll add it to this post when it's done).

The guy in the video above said that his speed was 172m/s and this was enough to achieve and orbit of 8.94km... Well, I was "orbiting" at my Cobras maximum speed, with full pips to engines and boost, and could easily hold 8.94km, but at a higher speed I should have been oribiting at a higher altitide (as you can see in this video increasing speed raises your AP, or apoapsis, which increases altitude https://www.youtube.com/watch?v=D7hmHoXGpi and in this video of Orbiter https://www.youtube.com/watch?v=g7flhlRV_Zs.) Also, just to see what happened, I throttled down and came to a complete stop, and my altitude held steady. If you could come to a dead stop in a true orbit, you'd plummet to the ground. I dropped to below 2km and performed the same actions, even turning off my thrusters, and got the same results.

Therefore, you are not truly orbiting in Elite Dangerous, you're simply flying around the planet at high altitude as you would if you were flying at low altitude. You can turn off the FA or your thrusters, but you're still just flying around the planet at a set speed, changing your velocity has no effect on your trajectory. It's not a true orbit.

Again, sorry.

... You weren't in FA off. Are you really debating the physics of ED when you don't even know EDs physics? When you turn FA off you start to fall. The ship makes no corrections. The only way to orbit in FA OFF is to put yourself in a real orbit. You cannot stay at a constant altitude in FA Off unless you are traveling fast enough your velocity away from the planet is completely canceled by gravity's pull. Which is definition orbiting. ED has real orbits. Why is it so hard for you to admit?

 

[John Rhys]

Your maximum velocity has no bearing on the orbital physics in Elite Dangerous. I've just recorded a video of myself in "orbit" around Enceladus (which is currently uploading I'll add it to this post when it's done).

The guy in the video above said that his speed was 172m/s and this was enough to achieve and orbit of 8.94km... Well, I was "orbiting" at my Cobras maximum speed, with full pips to engines and boost, and could easily hold 8.94km, but at a higher speed I should have been oribiting at a higher altitide (as you can see in this video increasing speed raises your AP, or apoapsis, which increases altitude https://www.youtube.com/watch?v=D7hmHoXGpi and in this video of Orbiter https://www.youtube.com/watch?v=g7flhlRV_Zs.) Also, just to see what happened, I throttled down and came to a complete stop, and my altitude held steady. If you could come to a dead stop in a true orbit, you'd plummet to the ground. I dropped to below 2km and performed the same actions, even turning off my thrusters, and got the same results.

Therefore, you are not truly orbiting in Elite Dangerous, you're simply flying around the planet at high altitude as you would if you were flying at low altitude. You can turn off the FA or your thrusters, but you're still just flying around the planet at a set speed, changing your velocity has no effect on your trajectory. It's not a true orbit.

Again, sorry.

Turning off FA AND the Thrusters will send you crashing down to the planet. I have no idea why, but turning off just the thrusters OR the FA does not completely disable one or the other.

 

[CmdrJacks]

It's not even as complicated as that CmdrJacks. Your speed in ED is your absolute velocity and has no bearing on what you do in orbit. You could "orbit" in a sidewider or cobra, or any ship for that matter, at 1m/s if you wanted, because you're not really orbiting. It makes no difference if you're 30m above the surface or 8km above the surface, because you're simply flying around the planet not orbiting.

TBH I've not experimented with orbiting in ED as it seems futile given the wonky physics. I did see Scott Manley got an orbit going recently on a particularly small moon. He got forward velocity balanced with his ship's rate of falling so that he was continuously missing the ground (orbit 101). Even so, it seems futile because you could never rendevous with another craft as for a given height the two ships would have to be moving at different velocities and you're also limited by ship top speed as to what size planet you can orbit around. I think the salvage missions would be a lot more interesting if you had to line up an orbital rendevous with the canisters rather than trying to chase them down to the ground when they spawn in but I know that kind of gameplay isn't everyone's cup of tea considering how many complain of not even being able to orbit Kerbin in Kerbal Space Program.

Then again, KSP is a much more popular game than ED so maybe they are the ones who have it right after all.

 

[John Rhys]

Oh, that was such a good thread. I'd pretty much forgotten everything I wrote in there. Dcello was a good fella (if not a little abrasive, at times)...been gone a long time now

Just out of curiosity, as it seems you are a physicists: What do you think of this? http://aerorocket.com/WarpMetrics.html

 

[peteuplink]

... You weren't in FA off.

I was FA off twice in the video, it had no effect on orbit mechanics...

Turning off FA AND the Thrusters will send you crashing down to the planet. I have no idea why, but turning off just the thrusters OR the FA does not completely disable one or the other.

I'll give it a try...

Edit 1: Tried with both thrusters and FA off now... I did drop altitude a little with thrusters and FA off, but not due to a realistically decaying orbit. Video uploading.

Edit 2: I've added the video below. As you can see I tried it with FA off and with FA off I boosted to see if an increase in velocity would raise my apopasis and increase my altitude. The only times the altitude raised was when I wasn't holding the ship exactly at zero, but you will notice that when I boosted with the nose slightly down I lost height, with it slightly up I gained height, as an aeroplane would. But as for a ship in orbit, that's not realistic. Even with a slightly downwards angle on the nose, the very act of raising velocity would widen the arc of my orbit, raising the apoapsis and therefore raising my altitude. it's quite simple, you increase speed in orbit, you go faster and you increase altitude. This didn't happen, so therefore NOT accurate orbital physics... Sorry guys, but it's just not. You can argue as much as you like, but I do know a lot about this subject. I ran an astronomy blog that posted stories for NASA, ESA and ESO through the Portal To The Universe website for three years. The blog had 150,000 readers a week. Okay, it was only something I did on Tumblr, but it was popular and it got some interest from space agencies, who allowed me to share their news articles. That's how I met the guys from the BBC's Sky at Night program who are now friends of mine on Facebook. I'm not saying any of this to brag, simply to point out that, even though I may only be an amateur astronomer, I am knowledgeable about the subject of space, physics and cosmology and I know and have spoken to some very knowledgeable people, including scientists, about it. If you do a search for PeteUplinks Universe you may still be able to find some articles online. I quit it because I went back to working on videogames and didn't have time to write anymore.

Apologies if anyone feels offended by the fact that I'm calling on Elites orbital physics, but Elite Dangerous is not a realistic space flight simulation, it's just a game.

[video=youtube;-80uwbNcyug]https://www.youtube.com/watch?v=-80uwbNcyug[/video]

 

[IndigoWyrd]

Of course it's a real orbit! it's live, happening now, in orbit around our planet. The delta-v needed to achieve low Earth orbit starts around 9.4 km/s. Atmospheric and gravity drag associated with launch typically adds 1.3–1.8 km/s to the launch vehicle delta-v required to reach normal LEO orbital velocity of around 7.8 km/s (28,080 km/h).

Anyway let's have a look at this video of an "orbit" in Elite Dangerous.

https://www.youtube.com/watch?v=XE7WPstMzsM

If we look at the video at 0:20 you'll see that he zeros his pitch angle and cuts his thrusters at a height of 8.9km above the moon at a speed of 172m/s, And then we enter a time lapse of the orbit. All well and good.

However, at the 3:03 mark of the video, you can clearly see that that the main thrusters of the ship start firing with a nose down attitude. Firing you engines like this while in orbit would alter your speed and therefore the trajectory of your orbit. The engines fire for 33 seconds until the video fades. While the engines are firing the video reaches the 3:24 point where he says "Three hours later. Ship returns to original position at the same speed." but if this was a true orbit, the fact that the engines are firing and that he was nose down would mean that he would not be at the same speed and would likely have dropped to a much lower orbit, if not out of orbit entirely by that point. Enceladus is only small and a 33 second burn would have big consequences on an orbit.

What I say is happening here is not that the maker of the video is actually orbiting the moon using orbital physics, but rather that he is simply flying around the planet using the same game systems that would keep you from crashing if you were flying at 172m/s at 1km above the surface.

The true test to see if it's real orbital mechanics would be to change your velocity and seeing if that raises or lowers your orbit in accordance to Newtons laws of physics. If your orbit trajectory doesn;t change and you simply speed up, you're not in an orbit. You're just flying around by artificial means that are programmed into the game.

Sorry, but that's the truth.

Given that he shut his thrusters off, I can't see how they'd fire, so it makes me wonder if what we're seeing is just some glitchy animation and not actually thrusters.

 

[Morbad]

Given that he shut his thrusters off, I can't see how they'd fire, so it makes me wonder if what we're seeing is just some glitchy animation and not actually thrusters.

Thrusters will fire, irrespective of their status (disabled/destroyed whatever), to maintain the artificial limits/caps placed on vessel velocity.

 

[peteuplink]

Given that he shut his thrusters off, I can't see how they'd fire, so it makes me wonder if what we're seeing is just some glitchy animation and not actually thrusters.

Maybe so, but you can see from my own videos that firing your thrusters while in orbit has no real effect anyway as it doesn't raise or lower your apoapsis, which is what it would do in true orbital flight.

 

[Morbad]

Enceladus is only small and a 33 second burn would have big consequences on an orbit.

Only if you assume they are burning at significant power.

Apologies if anyone feels offended by the fact that I'm calling on Elites orbital physics, but Elite Dangerous is not a realistic space flight simulation, it's just a game.

Not offended, but there are enough incorrect assumptions and other holes in your argument to convince me that you're wrong.

If one can achieve orbit within the hard speed caps the game imposes, the physics are accurate enough and this has been repeatedly demonstrated.

 

[peteuplink]

Only if you assume they are burning at significant power.



Not offended, but there are enough incorrect assumptions and other holes in your argument to convince me that you're wrong.

If one can achieve orbit within the hard speed caps the game imposes, the physics are accurate enough and this has been repeatedly demonstrated.

Well I've said all I can say about it, and I've given you some of my credentials to show that I'm not making this stuff up... If you can't accept it, then I can't say anymore...

[video=youtube;C5hka9rxIWI]https://www.youtube.com/watch?v=C5hka9rxIWI[/video]

[video=youtube;IC1JQu9xGHQ]https://www.youtube.com/watch?v=IC1JQu9xGHQ[/video]

 

[John Rhys]

Maybe so, but you can see from my own videos that firing your thrusters while in orbit has no real effect anyway as it doesn't raise or lower your apoapsis, which is what it would do in true orbital flight.

It could very well be, that you can't really turn off anything - just because FDev doesn't want you to, the Pilots Federation does not want you to or for whatever reason. I see your argument, but just because we can't do it with our ships doesn't mean the physics are crap. Orbital Mechanics may also just not have been integrated by FDev, because it isn't necessary for the gameplay. There is no reason, why you HAVE to get into a stable orbit apart from Stations. So FDev could very well have implemented Newtonian Physics but "canned" the Orbit, just becauce it doesn't make any sense in gameplay.

What happens if you reboot your ship, while not in a stable orbit? E.g. to slow or way to fast?

 

[Solman]

Maybe so, but you can see from my own videos that firing your thrusters while in orbit has no real effect anyway as it doesn't raise or lower your apoapsis, which is what it would do in true orbital flight.

If you could just make a video of getting on orbit playing Rogue System. But of course, not comparable to ED since it is a far more accurate simulation of space flight. Might be a moot point.

 

[peteuplink]

If you could just make a video of getting on orbit playing Rogue System. But of course, not comparable to ED since it is a far more accurate simulation of space flight. Might be a moot point.

Well I have toyed with the idea of doing an Orbiter video and showing what happens if I try to do a dead stop like I did in Elite Dangerous, but because the game is different they'd still argue it wasn't accurate. You see, David Braben and Michael Brookes have spread so much about the supposed scientific "accuracy" of Elite Dangerous that it's become like holy scripture and anyone that tries to say otherwise, even if they know a lot about space and physics and provide proof, is wrong... it's a bit like trying to talk to Trump supporters.

 

[beta]

Not quite sure what your video (the second one) is attempting to prove?

If you are implying via your boost your apoapsis was not raised - how do you know? You definitely did not wait until you reached your new apoapsis - it was a matter of seconds. Where were you in your orbit? Did you actual complete an orbit to see what your apoapsis and periapsis were? How are you so sure you did not increase it? When you make a large burn tangetially to your stable orbit, your apoapsis doesn't just magically appear where you are currently at, it will be much further along your orbit, generally relative to the amount you burned.

I am not proficient enough in calculating orbital mechanics to give you a solution to attempt to prove or disprove it's existence in E: D. You would need to attempt to create a parabolic orbit from your stable orbit that intersects with the surface or a hyperbolic orbit that attains escape velocity. Then you need to apply the dV at the proper inclination and direction and wait. Probably a fair amount of time (10s of minutes or so). Boosting at a tangent along your orbit, waiting for 30 seconds, then claiming orbital mechanics doesn't exist seems a bit weak to me ...

 

[Substacer]

I think the salvage missions would be a lot more interesting if you had to line up an orbital rendevous with the canisters rather than trying to chase them down to the ground when they spawn in but I know that kind of gameplay isn't everyone's cup of tea considering how many complain of not even being able to orbit Kerbin in Kerbal Space Program.

This kind of gameplay would require a time acceleration mechanic, which you can't do in most of the multiplayer games. What we have in ED is a pretty reasonable compromise in my opinion.

 

[peteuplink]

Not quite sure what your video (the second one) is attempting to prove?

If you are implying via your boost your apoapsis was not raised - how do you know? You definitely did not wait until you reached your new apoapsis - it was a matter of seconds. Where were you in your orbit? Did you actual complete an orbit to see what your apoapsis and periapsis were? How are you so sure you did not increase it? When you make a large burn tangetially to your stable orbit, your apoapsis doesn't just magically appear where you are currently at, it will be much further along your orbit, generally relative to the amount you burned.

I am not proficient enough in calculating orbital mechanics to give you a solution to attempt to prove or disprove it's existence in E: D. You would need to attempt to create a parabolic orbit from your stable orbit that intersects with the surface or a hyperbolic orbit that attains escape velocity. Then you need to apply the dV at the proper inclination and direction and wait. Probably a fair amount of time (10s of minutes or so). Boosting at a tangent along your orbit, waiting for 30 seconds, then claiming orbital mechanics doesn't exist seems a bit weak to me ...

If you don't get it then I'm not explaining it to you, and even if I did you'd just ignore it anyway.

Actually no, I'll give it a go, but don't blame me if you don't get it. When I boosted, the ship accelerated. The ship accellerates so quick in ED that you would be able to tell if your apoapsis had risen because your altitude would raise. Also, if you slowed down (and I stayed stationary for quite a long time - more on this below) your apoapsis would drop. But my altitude stayed level at all times with only very minor fluctuations... So no orbital physics.

Now as for the stationary thing. it's not possible to come to a dead stop in orbit unless your in a geosyncronous or geostationary orbit. And even then you've not stopped, you're moving at almost the same speed as the planet is rotating. A Geosynchonous Orbit (GEO) takes a satellite around the Earth at a rate of once per day, keeping it roughly in the same area over the ground. A Geostationary Orbit (GSO) is a geosynchronous orbit with an inclination of zero, meaning, it lies on the equator. To achieve a geostationary orbit around Earth you need a perigee of about 180 kilometers, an apogee of about 36,000 kilometers and an inclination of 19.3 degrees.

At the height I was in the game I would have been unable to achieve a geostationary orbit, because I wasn't high enough. Now obviously it's not as high as Earths 36,000 km, when orbiting Enceldus, but it wouldn't be as low as 8.9km either. What would have happened if I'd slowed my orbital velocity is the apoapsis would have dropped, but because everything moves in an arc (even if you fire a bullet and drop a brick at the same time on Earth, the bullet and the brick would both hit the ground at the same time but at different locations) you would not drop straight down as I did in the game, you would follow a curve down to the ground... So that's another proof that there are no orbital physics in Elite Dangerous.

 

[Monk]

Just out of curiosity, as it seems you are a physicists: What do you think of this? http://aerorocket.com/WarpMetrics.html

Former nuclear physicist, anyway. I made a move from lab coat to a polo shirt in the software business years ago.

The math looks fine, though as a former practitioner of applied physics (making theoretical physics relevant to engineers) my first investigations would go to limitations and logistics of scale. Most limitations here will come in the form of "not small enough", "not powerful enough", or "not persistent enough".

Even just for a single seater ship, like a Sidey, we have quite a ways to wait for the applied physics and the engineering to get to the compact, powerful and long-lasting power source that would be needed.

As for the theory itself, it seems the most plausible for FTL in our dimension.