A thorough report of my findings

Daedalao · Post by **Daedalao** » Thu Feb 12, 2009 1:21 am

Okay, so Wasp and I spent well over an hour testing a few things around Sapphire. He's the math guy, I'm just the test dummy. And I'm probably missing a few things...

Anyways, we were trying to establish Geosynchronous orbit at around 200000 altitude. I do know that with minor adjustments to his inertial thrust, Wasp managed to keep an altitude of 200002-200015. This was with his inertial velocity set to 130. This produced an odd result though. A positive velocity while falling. So at 200k alt I couldn't set my inertial thrust to 130 exactly, so I had to set it to 128, which caused me to drop altitude at a rate of about 1 altitude unit per every 2 seconds.

So we continued these experiments and noticed that gravity was affecting us ever so slightly. The only gravity recordings I have are for 161361 alt (28grv) with a velocity of 140. And for around 2000 alt (848grv) velocity of 120.

I have more to say, but I've never been very good with numbers and so my brain hurts. Anyways, just some data from Wasp and I. Also, screenshot.

[Edited on 2-12-2009 by Daedalao]

Wasp89 · Post by **Wasp89** » Thu Feb 12, 2009 4:05 am

Haha, we had so much fun! I thought it was absolutely brilliant that we could fly our craft such that we would remain almost completely stationary, even in a gravity field. I'm still trying to wrap my head around the data we gathered tonight, as a lot of it isn't very intuitive.

There are still a few things which are confusing me. We first managed to make ourselves stationary in orbit under "powered" flight with IDS on, but when IDS is turned off the ship stays stationary despite the pull of gravity. This should not be possible given the downward acceleration of gravity on our ship. With IDS turned off, there is no power to the engines unless we are using the afterburners or the inertial thrusters, so there should technically be nothing holding us up that is fighting the pull of gravity. I can, for a great amount of time, hold my ship almost completely stationary in space, inside a gravity field, on inertial. This should not be possible.

I think I may have a slight understanding, now, of how the physics system is constructed. The game engine does not take into account the force output by our engines on our craft, but instead looks to the number displayed on our velocity indicator to decide if we should be able to escape the gravity well or instead will fall towards it. That is why we get a positive velocity reading, even if we are stationary (when we are facing away) or a negative velocity reading if we are facing in the direction of the acceleration of gravity, or down.

Another thing that is confusing me is the gravity indicator. I did a few tests and discovered that at an altitude of 200000 with a "velocity" reading of 0 (meaning, there was not momentum/force in the direction opposite of the pull of gravity) The gravity indicator read "75." When we were stationary at that same altitude, meaning we had, again, a "force equal but opposite to the pull of gravity" holding us at that altitude, the gravity indicator read "25." The numbers dropped off very quickly after that, as soon as we had a net upward true velocity, though I do not have any further measurements at this time.

The good news is this: I do not think that these inconsistencies with real physics will have an effect on our ability to achieve an actual, true orbit in a gravity field. Daedalao had some success for holding a relatively steady altitude for (if I remember correctly) about 20 seconds, which is very impressive. Already, I find it remarkable that we were able to stay stationary in a gravity field, and am looking forward to performing more experiments.

I will keep experimenting and try to figure out how to apply the data we have taken so far. I'm hoping that the calculations won't be too difficult, and if I can learn to correctly interpret the data we have from our attempts at holding our craft stationary, I should be able to come up the acceleration of gravity at the altitudes we tested, and from that be able calculate an almost exact velocity at a given altitude that will allow us to maintain a decent orbit with a low decay value. At worst, we shouldn't have to make more than a few minor adjustments along the way.

I have also been thinking about ways of entering this orbit, and I'm pretty sure I have a solid system devised that will allow us accomplish this tricky bit of flying. With the right amount of finess, the right values and a little help from the nav computer, I think it can be done and can be repeatable.

Furthermore, once we have the data for performing a stable orbit at a few different altitudes, I should be able to come up with a formula that will give the escape velocity parallel to the ground at any altitude.

I'm definitely open to any suggestions, comments, and observations any of you may have. I'm going to have a tough time as it is, so if you have an idea on how to interpret the values above, just post it here!

[Edited on 2-12-2009 by Wasp89]

Skiiwa · Post by **Skiiwa** » Thu Feb 12, 2009 4:24 am

LOL!! Ouch Guys. Your Velocity vector has escaped my angular momentum

Daedalao · Post by **Daedalao** » Thu Feb 12, 2009 4:44 am

The main problem with the data gathered, is that I have no idea what unit of measure is being used for any of the numbers gathered.

I think I know what happened with my orbit... instead of being a circular orbit it was most likely elliptical. The problem ended up being that the gravity well wasn't large enough to maintain an elliptical orbit. I'll be testing this theory if I can figure out what units of measure are in use. Or I may have to convert them to something I understand.

I am guessing that the gravity measurement is in thousandths. (ie one earth unit of gravity = 1000) The only reason I can figure this is based on sapphire's ecology and it's size. Any comments would be useful.

[Edited on 2-12-2009 by Daedalao]

verbosity · Post by **verbosity** » Thu Feb 12, 2009 8:30 am

LoL,
Good first attempts guys!
possibly a star might be easier for you inital attempts, you can get a higher gravity from it.
Also I'd probably suggest that you'd need to end up on inertial for it to be a 'true' orbit.
one of the issues you'll find is that gravity does not seem to appear on your motion readouts.

But seriously good work!

Daedalao · Post by **Daedalao** » Thu Feb 12, 2009 9:13 am

that's just it, we were operating on inertial.

Daedalao · Post by **Daedalao** » Thu Feb 12, 2009 12:50 pm

Some more information, I don't have the exact numbers but I noticed that while accelerating, anything over 200kph (I'm going to pretend that's the speed) would cause me to rocket out of the atmosphere... until I reached around 1200kph. Then I would start to lose altitude... Some strange forces at work. I did pretty well at maintaining an orbit at 300022 around Talison. minor corrections kept me within my set limits of 300001-300099... I didn't have the time to make a full orbit, but it's my belief that with this, I might be able to maintain that altitude for prolonged periods of time.

Wasp89 · Post by **Wasp89** » Thu Feb 12, 2009 9:06 pm

I did a little more experimentation today, and I must admit that I'm feeling a little pessimistic about the theoretical possibility of obtaining a true orbit in EL. I set a nav point along the equator of Sapphire and at an altitude of 200000, with the point resting on the imaginary positive x-axis that runs through the center of the planet. I did repeated jumps at a heading of 0 degrees and with my target reticle centered on the 0 bar on the pitch ladder, so that I could be sure that when I passed through the nav point I was almost perfectly tangent to the ground "below me" (actually, directly to my left). I would jump in, use reverse afterburner to slow myself down and then let IDS take over until I was at my desired velocity. I did several tests, passing through the nav point at various speeds and turning IDS off the instant I passed through it. At higher speeds, as one would expect, my altitude steadily began increasing as my ship overcame the effects of gravity. The finding that is making me pessimistic, at this point, is this: At lower speeds my altitude would start to decrease, but would then start to increase again after a few minutes of steady decline, until I ultimately achieved an altitude of 200000 again and continued to rise. Needless to say, more tests are required before I can confirm anything, and it would help if I could gain a better understanding of how the game engine treats ship velocity and momentum. There may be a very, very small sweet spot that allows you to achieve orbit, but I agree with Daedalao and suspect that this orbit will be rather elliptical. The challenge with this, of course, is to ensure that this ellipse does not A: take you out of the gravity field and B: bring you through the atmosphere.

More to come, stay tuned...

[Edited on 2-12-2009 by Wasp89]

tha_rami · Post by **tha_rami** » Thu Feb 12, 2009 9:10 pm

This is amazing, fun playing with the physics

Wasp89 · Post by **Wasp89** » Thu Feb 12, 2009 9:21 pm

Also, I agree with Verb in that a star may become our best bet for achieving this elliptical orbit, as the gravity is stronger and the depth of the gravity field is greater, allowing for a narrower ellipse. Again, to be successful, the ellipse must not take us below a certain altitude (the "crush point") or out of the gravity field, but with a star we will have more play between these two values.

I may start experiments with stars to see if it is even possible to achieve orbit, and then graduate to attempting elliptical orbits around planets if I am successful at orbiting stars and as I begin to perfect my methods.

[Edited on 2-12-2009 by Wasp89]

Wasp89 · Post by **Wasp89** » Thu Feb 12, 2009 9:47 pm

Early Verdict:

I now believe, because of the physics system in EL, that it will be impossible to achieve an orbit of much more than 1/4 the distance around an object. My preliminary findings support this theory, and I will attempt to explain it further in the future. For now, it will suffice to say that I believe that the net direction of travel is calculated by determining what velocity your ship would be going if it wasn't in a gravity field, and then adjusting that velocity based on the pull of gravity. Since the velocity that your ship WOULD be going outside of a gravity field does not change without pilot input, the ship should travel in a straight line. Thus, once the ship has gone exactly one-quarter of the way around a gravity field, the direction of travel (that the ship WOULD be going in) will be directly opposing to the pull of gravity, and so one of two things will happen: A) The ship has enough "velocity" (that is the, velocity it WOULD have) to defeat the pull of gravity and will travel out into space, or B), the ship does not have enough "velocity" and will instead fall back down to the planet. Since the forces are exactly opposing (though one really isn't a force), there will be nothing to pull the ship from side to side, and so the orbit will not continue. The game does not read gravity-induced velocity alterations as the true heading of the craft: this can be noted by the icon that indicates direction of travel that will stay centered in a reticle even when the direction of travel is being affected by the gravity field. Therefore, all lateral velocity (assuming the ship is still pointed along a bearing of "0" degrees) will not be taken into account, the game engine will reset the true velocity of the ship and there will be nothing to pull the ship around to the other side of the planet. Diagrams, I think, will help to further explain what I am trying to say, and I shall try to post some in the future.

Of course, tests will still need to be conducted to confirm my theory, but I fear that indeed those tests will confirm that a true orbit in EL is not possible.

[Edited on 2-12-2009 by Wasp89]

Wasp89 · Post by **Wasp89** » Thu Feb 12, 2009 11:38 pm

Okay, here is a diagram I made which might help you picture what I think is going on.

Example 1

Keep in mind, the term "velocity" implies a vector with both direction and magnitude...i.e., Velocity is different then speed, which is simply a measure of magnitude.

Explanation:

The ship has an initial velocity, Vo, of an arbitrary value. The game engine recognizes this initial velocity, which is equal to the velocity the craft would experience in open space outside of a gravity field. The game engine then uses a formula to calculate the effect of gravity which the craft should experience, based on the direction of craft's Vo relative to the acceleration of gravity. The craft's actual velocity is then adjusted to match this calculation, but the velocity that the hud reads (and the one that is used for further calculations) does not change direction or magnitude. Thus, as the ship continues along it's new path, the game engine continues to use this original Vo to recalculate the actual velocity of the craft, but does not refresh the Vo, using the same and original value in each subsequent calculation. Therefore, once the angle between Vo and the acceleration of gravity begins to increase, the gravitational force on the craft will not be able to compensate for the Vo and the craft will therefore cruise right on out of the gravity field.

If this Vo is too small, as the angle between Vo and the force of gravity increases towards 180, the force of gravity overcomes the velocity for the craft and the craft is pulled down to the planet's surface.

As I said, this is all still a theory, but it makes sense and would explain all of our data.

[Edited on 2-12-2009 by Wasp89]

[Edited on 2-12-2009 by Wasp89]

Daedalao · Post by **Daedalao** » Thu Feb 12, 2009 11:42 pm

I told you we should have started with stars.

Anyways, yes I'm not sure it's possible to achieve a circular orbit around an object. But I'd like to spend the time to figure out if maybe we're just approaching it incorrectly. Keep in mind that even if we don't achieve an orbit that doesn't have a decay, at least we're trying! Nothing wrong with the old college try!

Wasp89 · Post by **Wasp89** » Fri Feb 13, 2009 12:03 am

One more way to look at it:

Gravity in this game acts like a second velocity vector on the craft, NOT like an acceleration. The game takes what our velocity indicator reads, in any direction, and calculates the pull of gravity based off of this. It "assumes" that IDS is on and our engines will compensate such that we fly in a straight line path, or as close to a straight line path as possible. This is very practical and makes a lot of sense for ease-of-play, as if gravity had an actual affect by changing that velocity indicator and then recomputing based off of that new velocity (thereby acting as an acceleration), we would have to ride the reverse afterburners every time we wanted to go down to a planet's surface as we would be constantly accelerating until we broke atmo, when air resistance begins to slow us down and brings us to terminal velocity. The alternative would be breaking atmo at a shallow angle. Unfortunately, with the game engine designed this way (IF it is indeed designed this way...) it also means that an orbit is not possible.

That all-said-and-done, we CAN still successfully do a quasi-orbit. With IDS on, if we simply adjust the nose of the craft (and thereby the "Vo") every so often, we can achieve a relatively stable orbit. I would even go so far as to guess that we only have to make this adjustment every 1/6th of an orbit, which in-and-of itself is pretty remarkable.

Questions, class?

[Edited on 2-13-2009 by Wasp89]

49rTbird · Post by **49rTbird** » Fri Feb 13, 2009 12:15 am

Makes my head hurt! (lol)

:P:P

Post by **Vice** » Fri Feb 13, 2009 1:06 am

Deep stuff

Manually trimming adjustments are probably the most feasible option. Although I wonder about setting the orbital pathway. I see the X and Z values taken into account, what about Y? If your initial approach vector is not perfectly lined up with the needed orbital path (maintaining a perfect distance around the center of the planet relative to all 3 coordinate/direction variables) as you set the required speed and orientation, it might result in an off-center pathway, eventually causing a drift into space or descent into the atmosphere (plus you would have to constantly make small adjustments in an attempt to maintain the orbit... a very difficult thing to do). I might be off on this, but one technique that occured to me to make an attempt a bit easier would be to perfectly align yourself with the Y position of the planet, keeping pitch precisely at 0, then working to establish an orbit just using left and right to adjust X/Z and trimming velocity as you travel around the planet to find the needed configuration. It would remove one of the variables from the equation that might be the most challenging to get right (I can imagine trying to manage an orbital pathway manually with diagonal pitch and yaw would be quite a difficult challenge).

[Edited on 2-13-2009 by Vice]

Daedalao · Post by **Daedalao** » Fri Feb 13, 2009 3:48 am

I'm going to go ahead and look into this. Because if newtonian physics are in play, it should be plausible to do this... mind you as I have said before, I'm no good at math, but I'm using this to help... http://www.braeunig.us/space/orbmech.htm

Keeping things perfectly aligned will be a challenge, but I'm sure I can overcome it. Something I was thinking about was to upgrade my ships frame to a leviathan and downgrading my engine so that I can achieve more finite adjustments to thrust. Wasp, if you want you can spot for me and I'll feed my telemetry to you as quick as possible. The only reason I say this, is that I have no idea what the heck you're doing with the numbers. I've always flown by feel

(this includes simulators and actual aircraft)

Eventually, if we get a standard equatorial orbit going, I'd like to try setting up a simulated Hohmann transfer orbit. This would involve going from planet Sapphire to it's moon, mainly because any other distance would be too tremendous to do feasibly in a few hours.

[Edited on 2-13-2009 by Daedalao]

Daedalao · Post by **Daedalao** » Fri Feb 13, 2009 5:31 am

Apparently, Slammers24/7 doesn't like me all that much, because I just lagged out. However, I'm fairly confident that if I can do what vice said and keep my ship aligned on the Y axis, I'll be able to pull this rabbit out of my hat. It's a lot easier said than done, due to the minute adjustments that need to be made. I was thinking that I'll try launching into orbit from the surface of Sapphire later tonight, as a ballistic trajectory maybe just what the doctor ordered. The problem is I don't know if this is feasible at the moment. I will try later however.

Wasp89 · Post by **Wasp89** » Sat Feb 14, 2009 9:55 pm

See the new thread for a thorough report of my findings for the potentiality of obtaining an orbit in a gravity field in EL.

[Edited on 2-14-2009 by Wasp89]