Author Topic: A quesiton on tracers..one for the grad students (Read 797 times)

WhiteHawk · « **on:** December 24, 2003, 07:06:32 PM »

Ok. when I am firing the bullet goes straight therefore the tracer trail goes straight. (distregard wind, gravity, and drag). When I am banking and fire, the bullet goes straight obviously, therefore the tracer trail goes straight. But should it apper to be curving??
the projectile appears to curve since my perspective is changeing against the axis of the projectile, should the tracer trail appear to curve also? They go straight on il-2 also, but something always kinda rubbed my senses the wrong way about them. As well as Ah2 tracers? when Firing straight on they look fine, but when I am banking they should look curved to me??
Hmmm,, I will break out my yellowing Calculus book and see what newton has to say about this.
Anybody care to venture a guess? How about a some equations and possibly a proof?

mold · « **Reply #1 on:** December 25, 2003, 08:48:42 AM »

Yes, when you are turning you are in an accelerating frame of reference. So things that are going straght in an inertial frame of reference (the stationary world) look like they're accelerating (curving) to you. Merry Xmas!

WhiteHawk · « **Reply #2 on:** December 30, 2003, 09:36:06 AM »

yes..I believe since the smoke of the tracer is just a smaller particle than the projectile. it should APPEAR to bend just as the projectile appears to curve, disregarding the wind effect.

mold · « **Reply #3 on:** December 30, 2003, 01:01:59 PM »

Sorry, I guess I didn't quite follow the question the first time. The answer is that the smoke trails should not curve. However, they should move with the tracer as it curves away from you.

To put it another way, every point along the smoke trail accelerates from your perspective, and everything has the same acceleration from your perspective.

Also keep in mind that at any instant in time, a line in an inertial frame looks like a line in an accelerating frame (we are ignoring relativity here). Things don't change their shape in an accelerating frame. All points in space have the same relative acceleration applied to them.

hitech · « **Reply #4 on:** December 30, 2003, 01:34:03 PM »

Had a strang experiance trying to shoot down an RC plane with a paint ball gun. When you were tracking the plane with your gun and shooting fast. You could have sworn the paint balls were curving to the plane.

HiTech

Wadke · « **Reply #5 on:** December 30, 2003, 01:44:13 PM »

did ya shoot him down Hitech?

WhiteHawk · « **Reply #6 on:** December 30, 2003, 03:19:12 PM »

Right, the smoke trails should NOT curve, but shoyuld they appear to curve from the perspective of the banking planes pilot?
I say that if the projectile appears to curve, then the tracer trail should appear to curve also. Or bend would be a better word.
That would be nearly impossible to model, but theoretically, it waould have to hold. let me go experiment a bit.

mold · « **Reply #7 on:** December 30, 2003, 03:54:02 PM »

The projectile curves, but the smoke trail does not. The entire trail accelerates, so it remains a straight line.

Waffle · « **Reply #8 on:** December 31, 2003, 10:09:18 AM »

Quote

Originally posted by hitech
Had a strang experiance trying to shoot down an RC plane with a paint ball gun. When you were tracking the plane with your gun and shooting fast. You could have sworn the paint balls were curving to the plane.

HiTech

LOL - been trying to devise a way to use larger bottle rockets in a pipe (simulated SAM) or roman candles.....get a .60 trainer.....fly it in nice patterns above the feild.....boom!

Happy New Year

Cobra412 · « **Reply #9 on:** December 31, 2003, 09:26:38 PM »

With the projectiles and ranges we are dealing with here it would seem you shouldn't be able to see the drop affect. Assuming the rate of drop of the given munition and the attitude and direction of the aircraft relative to the munition, no curve would ever be seen. It would appear that it's curving but overall it's not as drastic as it my appear. That again depends on many factors here. I guess what your getting at is what it should look like opposed to what it's actually doing. In that case it should seem to fall away drastically not necessarily curve.

redphoenix · « **Reply #10 on:** January 01, 2004, 12:41:10 PM »

Actually Hitech... it is a reference point curve (and to everyone reading this, 'Relativity' has come into play here and is actually a fine 'textbook' example for demonstrating 'Relativity' to students) and actually explains what happens to that particule of light as we accelerate away from it.... I need a PPT to show it here so words will probably fail....

1. You fire.... your firing imparts speed on Axis 'A' relative to you as 'point of origin' and the speed of the paintball moving away from you (no gravity or wind effects)
2. You follow the target RC\AC with your paintball gun which, when you fire, imparts speed on Axis 'B' and that speed and axis is relative to the target

We have 2 axis' with different direction and speed... now we need the observers... and the actual application of 'relativity', so to speak...

1. This is the RC\AC perspective... the 'pb' hitech fired is coming straight at it.
2. Hitech looking down his barrel's 'line of sight' at the RC/AC sees the 'pb' he just fired curve away from him through his peripheral vision
3. Third-person observer watching the 'pb' not on axis A or B sees the ball following a curved path to the RC/AC as the RC/AC comes into his peripheral vision. Here is the trick though... and that is the reference point... this person will see the 'pb' as moving in a straight line UNTIL his reference point changes from the point of origin (with no speed or direction of travel) to the point of destination (with speed and direction of travel) and suddenly the 'pb' picks up a 'curve' in its perceived direction of travel, even though nothing has changed in the paintball's speed or direction... just the reference point.

Relativity at its simplest...

Now...we can go into many, many extrapolations from this point and each has a different meaning in cause and effect and what it means to the physics in our game... and none of this even considering the wind, gravity and kenetic energies involved... then there is the (2 client/server) references and the time to loop/(communicate/calculate)/complete for each firing of each bullet.

So the next time you see a 'strange visual effect' in the game... apply this model and see if it is so strange after all...

Sway · « **Reply #11 on:** January 01, 2004, 03:35:00 PM »

lol.. I do less constructive things with paintball guns..