Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: bustr on July 17, 2013, 06:48:56 PM
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I cannot remember if tracer rounds in our game have a different trajectory than non tracer rounds.
I was testing tracers turned off with this update. I noticed I was using fewer rounds to kill the drones. I could be seeing things but, that would mean tracers are modeled with different ballistics. I was seeing closer patterned hit sprites when I connected without tracers.
Also found I had a higher hit rate with the Yak 9T against drones if I used the 12.7mm first, then tapped the NS-37 when I had sprites from the 12.7mm. Saved plinking around with the NS-37 looking for contact.
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Also found I had a higher hit rate with the Yak 9T against drones if I used the 12.7mm first, then tapped the NS-37 when I had sprites from the 12.7mm. Saved plinking around with the NS-37 looking for contact.
i do that all the time with any plane that has cannons and mg's...if only i could shoot better.
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Danny told me that tracers in real life have a flatter trajectory because they lose mass in flight.
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The 20mm cannon ball ammo and HE rounds weighed near the same but the tracer round was a little heavier.
If I were making the ammo as a manufacturer, I'm pretty sure I would have tested and modified the amount of "powder" in the tracer rounds to make up for it as much as possible.
After the war, they made all 3 ammo types weigh as close as possible and my dad reports the 20mm cannons in his ride fired all 3 with the exact same trajectory because he strafed ground targets often in places where the humidity allowed you to see the path of the bullets.
In fact, it was so humid that his engine idling on the deck of the carrier caused the tips to make corkscrew contrails.
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"I cannot remember if tracer rounds in our game have a different trajectory than non tracer rounds."
No. They are all the same.
The burning tracer material may also cause the projectile to tumble unexpectedly if the material does not burn evenly.
I recall that e.g. in MG151/20 the powder amount was not compensated so AP and MG had different trajectories and MG had greater MV because it was so light.
-C+
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The 20mm cannon ball ammo and HE rounds weighed near the same but the tracer round was a little heavier.
If I were making the ammo as a manufacturer, I'm pretty sure I would have tested and modified the amount of "powder" in the tracer rounds to make up for it as much as possible.
After the war, they made all 3 ammo types weigh as close as possible and my dad reports the 20mm cannons in his ride fired all 3 with the exact same trajectory because he strafed ground targets often in places where the humidity allowed you to see the path of the bullets.
In fact, it was so humid that his engine idling on the deck of the carrier caused the tips to make corkscrew contrails.
Tracers illuminate by burning material, therefore the mass changes in flight. Non tracers have a consistent mass. How can they fly the same?
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Because they were designed to by the manufacturers?
I'm just repeating what was related to me by a guy who's fired thousands of both in real life.
The atomic mass of lead is 207 while the mass for phosporus is 30 and the mass for magnesium is 24.
Very little change in weight as it burns.
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tracers do change weight as they burn and the ballistic trajectory can alter differently depending on the type, caliber, and burn rate of the round. modern ammunition isn't as erratic as world war 1 and 2 ammunition did. and world war 2 tracer ammunition behavior varied from country to country based on the materials and manufacturing process. we're not talking something like a lightning bug all over the place but, depending on the caliber and the range, you could see the behavior if you were looking for it. in the heat of battle, the only thing you want to see from a tracer is if it's hitting the target.
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How many bullets between tracers? Does having tracers off give you a few extra bullet strikes on the target?
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.50 cal ball ammo bullets weigh about 700 grains. That's about 1 3/4 ounces.
The phosphorus that burns for a split second (the tracer) weighs practically nothing.
If the two didn't fly the same path, what would be the point?
(rhetorical question, of course. Those clever fellas back in the science lads figured out a way to get those pesky tracer rounds to fly the same path as the ball, the ap, the api, etc. That's why you have different types of tracer. They weigh the same with whatever they're belted with.)
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The phosphorus that burns for a split second (the tracer) weighs practically nothing.
If the two didn't fly the same path, what would be the point?
(rhetorical question, of course. Those clever fellas back in the science lads figured out a way to get those pesky tracer rounds to fly the same path as the ball, the ap, the api, etc. That's why you have different types of tracer. They weigh the same with whatever they're belted with.)
uh ok...so how do you explain m2 ball projectile weight is 700gr, tracer is 630gr, api is 639gr, armor piercing incendiary tracer is 619gr?? the weights have nothing to do with tracer types. the types are based on the way the tracers burn.
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In WWII, the 20mm tracer used by the USA weigh more than the ball or HE rounds.
No clue what your angle is, gyrene but I doubt the people who designed the rounds know less than you do or that they sent guys to war with tracers that nowhere near where the rest of the bullets are going.
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well Icepac i think a couple years of range practice testing weapons out to 1000 yards can give a guy a fairly decent idea...we didn't just take them out of the box, mount them up and release them without testing.
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well Icepac i think a couple years of range practice testing weapons out to 1000 yards can give a guy a fairly decent idea...we didn't just take them out of the box, mount them up and release them without testing.
I think Gyrene is correct if you look at shot out to 1000 yds. I'm willing to bet that the first 300 yds or so there wouldnt be a huge difference in tragectories but once the round are down range at 700 to 1000 yds you would start to see a difference.
I also have no doubt Gyrene put more than his shhare down range!
:salute
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I'd have thought the solution is obvious - make every round a tracer. There might be a benefit to a mass-diminishing round as the velocity reduces :)
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Hmmm....
The part of my brain that stores my limited amount of physics knowledge is fuzzily suggesting that once a projectile leaves the muzzle at a certain velocity, only friction and gravity affect its trajectory.
I could be wrong, but it seems to me that the velocity is a result of its acceleration in the bore, and once it leaves the muzzle it's in free flight, so its decreasing mass would not be an issue affecting trajectory, only its energy state throughout the flight......or.....?????
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You might be right Stash, but then I'm wondering why they can't exactly match the flightpath of tracer and non tracer by increasing propellent in the heavier projectile? Perhaps there is an aerodynamic difference?
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I'd say that due to differences in weight (even if aerodynamics were the same) the amount of propellant would only match the arrival time or flight path crossing of projectiles to a certain point, not for the entire flight path. But that is not without problems either.
In case of, say, MG151/20 and different weight projectiles it would be more desirable to match the flight path horizontally to a certain point and not the time of arrival since the time difference is practically negligible, where as if the horizontal flight path difference is great the majority of shots would miss if the tracer would be used as the guideline to direct aim.
Effectively this means that the heavier projectile could leave the barrel with less velocity than the lighter one but still cross a certain point with the lighter one (but at different time), since despite faster speed the lighter round will also decelerate faster due to worse kinetic energy retention. To calculate this point would be pretty wild process but I guess that is why there are tables of flight time and drop to certain distances to aid in combining a sensible belting, and what is more important to calibrate the sight as the propellant loading is what it is and cannot be changed on the field. That would mean that the weapons officer would tell the pilots prior to mission that the tracers can be used to direct fire for, say, up to 300 - 400 meters and that the aiming point is a few degrees above the center of the sight but at 600 meters the majority of rounds will land exactly where the sight is set where as at that distance the tracers may already fall below target, or still fly over it.
In best case the tracers' flight path would cross that of the heavier ones exactly at the desired sight point but there would still be differences at other distances.
If we got to micro level the matter gets even more complicated as the reducing weight will affect the flight characteristics but not necessarily in a positive way, on the other hand the erupting hot gases from burning tracer decreases tail drag etc etc etc.... :D
-C+
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Hmmm....
The part of my brain that stores my limited amount of physics knowledge is fuzzily suggesting that once a projectile leaves the muzzle at a certain velocity, only friction and gravity affect its trajectory.
I could be wrong, but it seems to me that the velocity is a result of its acceleration in the bore, and once it leaves the muzzle it's in free flight, so its decreasing mass would not be an issue affecting trajectory, only its energy state throughout the flight......or.....?????
Reducing mass would have an effect on the bullet's ballistic coefficient, which in simple terms is how rapidly it slows down as it goes downrange. Two bullets having the same size, shape, and initial muzzle velocity with one of them being lighter and therefore slowing down faster means the one that's slower has more time to fall over the same distance, so it will have a lower impact point.
I don't know anything specific about the tracer/non tracer scenario discussed here, but it wouldn't surprise me if it were true. In terms of aerial gunnery on vehicle size targets, I'd question how much of an impact it would have on anything other than the briefest of snapshots.
...On a slight tangent, the belts were generally mixed in some fashion, right? Tracer/API/Incendiary/? I'd bet there were similar slight ballistic differences between rounds.
Wiley.
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Danny told me that tracers in real life have a flatter trajectory because they lose mass in flight.
1st Aces High treats tracers and non tracers the same.
2nd loosing mass in flight would not cause a flatter trajectory. It would cause the bullet to drop more because less mass would make the bullet slow down more quickly. Hence longer time of flight to target, hence greater drop.
I am not saying that tracers do or do not have a flatter trajectory in real life, only that the causation you stated can not happen.
HiTech
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1st Aces High treats tracers and non tracers the same.
2nd loosing mass in flight would not cause a flatter trajectory. It would cause the bullet to drop more because less mass would make the bullet slow down more quickly. Hence longer time of flight to target, hence greater drop.
I am not saying that tracers do or do not have a flatter trajectory in real life, only that the causation you stated can not happen.
HiTech
:airplane: Sir, greatest respect for you and what you have done with this game! <S>...I have a question which I think only you could lay some question in my mind concerning the .50 cal ammo in this game. #1- Have the .50 cal been "de-nuted" as some claim. #2- Is there a chart, or resource where we can see which of the ammo has the most drop and how much each ammo drops, say in 1,000 feet. #3- Salute to Skuzzy for all the help he has been to all of us! <S>
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Tracer rounds will always fly slightly higher than ball rounds simply because of their original mass being less than ball rounds, and this mass decreases in flight as the phosphorous burns away.
It is easily visible firing GPMG belts of 1 in 5 tracer, at 6-800yds there is a pronounced variation in the impact zone :old:
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:airplane: Sir, greatest respect for you and what you have done with this game! <S>...I have a question which I think only you could lay some question in my mind concerning the .50 cal ammo in this game. #1- Have the .50 cal been "de-nuted" as some claim.
Of course not.
#2- Is there a chart, or resource where we can see which of the ammo has the most drop and how much each ammo drops, say in 1,000 feet. #3- Salute to Skuzzy for all the help he has been to all of us! <S>
Not that I know of. But you can bring up a target with the .target command at any range you wish, and see the amount of drop at different ranges.
HiTech
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Have the .50 cal been "de-nuted" as some claim.
This is one of the most constant claims in AH almost since the beginning. Especially after each update, you will read a lot like "oh great, HT has now nerfed the 0.50 cal" (or any other favourite piece of equipment).
If only a fraction of that had been true, the .50 would shoot cotton balls by now :D
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This is one of the most constant claims in AH almost since the beginning. Especially after each update, you will read a lot like "oh great, HT has now nerfed the 0.50 cal" (or any other favourite piece of equipment).
If only a fraction of that had been true, the .50 would shoot cotton balls by now :D
Overwhelmingly those are about the .50 cal. The only other I've even seen claimed is the German 30mm.
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This is one of the most constant claims in AH almost since the beginning. Especially after each update, you will read a lot like "oh great, HT has now nerfed the 0.50 cal" (or any other favourite piece of equipment).
If only a fraction of that had been true, the .50 would shoot cotton balls by now :D
:rofl :rofl :rofl
Earl all ordanace in AH is based on LB's,IIRC the 50 cals generate 1.1 pounds of destruction per round. You can test these things offline or in custom arenas by adjusting the damage required to destroy an object,ya it's over my head to Earl. These days you need to be a computer expert just to play games,not like the old days where a stick,rock or can could make for a great game!!!
BTW the post that stated the 50 cals were nerfed was about 13 years old back when AH was almost new! the damage model and the way it works has been changed since then this lead some to think HTC nerfed the 50 cals.
hope that clears thinks up for you abit.
:salute
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Tested 50 cal offline with the target.
P51D
Conv - 300
Alt 1000ft
Level speed 301 ias
Target 300 yards
Tracers on - Concentrated dispersion 5ftx5ft with random dispersion 10ftx10ft at 300 yards.
Tracers off - Concentrated dispersion 5ftx5ft with random dispersion 10ftx10ft at 300 yards.
The IP point was exactly the same relative to the gunsight center and target in both cases with the same 5Mil nose down movement during firing. I suspect that 5Mil nose down depression might have some influence to player complaints. This can be seen with fighters that have wing guns outboard of the main gear with the offline target while shooting on full zoom. "For every action, an opposite and equal reaction".
A case could be made for testing convergence combinations at target 200, 300, 400 to present dispersion clouds as a player aid. The AAF 1945 armorers harmonization manual had graphic illustrations of this for the P51D set to 333yd conv. The assumption for the 50cal and 20mm was an ever expanding 4Mil dispersion cone along the ballistic arc at all ranges out to max effective. The famous "Shotgun Effect".
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I think Gyrene is correct if you look at shot out to 1000 yds. I'm willing to bet that the first 300 yds or so there wouldnt be a huge difference in tragectories but once the round are down range at 700 to 1000 yds you would start to see a difference.
I also have no doubt Gyrene put more than his shhare down range!
:salute
Although interesting, its prob. irrelevant in that almost all ww2 aerial combat shots were done close in. At least it seems that was what was what pilots were trained to do. Eric Hartman for example, would advise to get in as close as possible, sometimes getting hit by the debris of the planes he was shoot at. Even in AH, its rare to make shots from more than 400 out, and according to all of you, there wouldn't be much of a diff between 0-~300 or so yards...
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1st Aces High treats tracers and non tracers the same.
2nd loosing mass in flight would not cause a flatter trajectory. It would cause the bullet to drop more because less mass would make the bullet slow down more quickly. Hence longer time of flight to target, hence greater drop. Objects of greater mass are more resistant to changes in their state of motion.
I am not saying that tracers do or do not have a flatter trajectory in real life, only that the causation you stated can not happen.
HiTech
This, gravity is a constant force, a falling heavy item accelerates as fast as a falling light item in a vacuum, so the loss of mass causes the round to have less inertia and thus slow down faster.
Is the loss of mass great enough to make a noticeable difference within normal fighting/firing ranges (0-400)?
EDIT: Are the drag coefficients similar for tracer rounds compared to normal rounds?
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Hmmm....
The part of my brain that stores my limited amount of physics knowledge is fuzzily suggesting that once a projectile leaves the muzzle at a certain velocity, only friction and gravity affect its trajectory.
I could be wrong, but it seems to me that the velocity is a result of its acceleration in the bore, and once it leaves the muzzle it's in free flight, so its decreasing mass would not be an issue affecting trajectory, only its energy state throughout the flight......or.....?????
Baring every shot has perfectly identical mass & shape. Also both rounds would have to have had perfectly equal amounts of force generated by the charge... All of which is not the case in RL. I wonder if the heat generated from the first shot would ever so slightly alter the shape of the barrel and/or alter the combustible characteristics of the charge.
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Tested 50 cal offline with the target.
P51D
Conv - 300
Alt 1000ft
Level speed 301 ias
Target 300 yards
Tracers on - Concentrated dispersion 5ftx5ft with random dispersion 10ftx10ft at 300 yards.
Tracers off - Concentrated dispersion 5ftx5ft with random dispersion 10ftx10ft at 300 yards.
The IP point was exactly the same relative to the gunsight center and target in both cases with the same 5Mil nose down movement during firing. I suspect that 5Mil nose down depression might have some influence to player complaints. This can be seen with fighters that have wing guns outboard of the main gear with the offline target while shooting on full zoom. "For every action, an opposite and equal reaction".
A case could be made for testing convergence combinations at target 200, 300, 400 to present dispersion clouds as a player aid. The AAF 1945 armorers harmonization manual had graphic illustrations of this for the P51D set to 333yd conv. The assumption for the 50cal and 20mm was an ever expanding 4Mil dispersion cone along the ballistic arc at all ranges out to max effective. The famous "Shotgun Effect".
:airplane: Thanks for your report sir and I will not reduce my converg to 300 instead of the 400 I have been using with the .50 cal aircraft!
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Just for fun...
Random dispersion is often more important on long distance shots and snap shots. "Shotgun Effect". Or the 4Mil dispersion cone at range describing your random round position at any point in time.
P51D
301 ias
1000ft auto level
x = feet
(x) = High density impact pattern cloud blob.
(x)x(x) = Impact cloud blobs with space between pattern high density impact blobs or random dispersion blobs.
RandomDispr = low density impact ring of random flyers.
----------------------------Pattern at Target Range(yards)
Convergence-----200-------300---------400-----------------600 Target Range
250-275-300-----(10x5)-----(5x5)-----(5x5)3(5x5)-----(10x10)10(10x10)
RandomDisper---(12x9)----(15x10)------(20x10)-------------(40x20)
300-275-300-----(10x5)-----(5x5)-----(5x5)3(5x5)-----(10x5)10(10x5)
RandomDisper---(12x10)---(10x10)-----(20x15)-------------(45x20)
Convergence--------200---------300----------400-------------600 Target Range
300-300-300-----(5x5)3(5x5)-----(5x5)-----(5x5)3(5x5)-----(5x5)10(5x5)
RandomDisper------(15x10)------(10x10)-----(20x15)-----------(40x20)
350-375-400-----(5x3)5(5x3)------(8x3)-------(8x4)-----------6x5)5(6x5)
RandomDisper------(15x10)------(10x10)-----(15x15)-----------(25x35)
300-400-500-----(2x5)5(2x5)-----(10x4)-------(8x8)------------(10x10)
RandomDis----(10x10)5(10x10)--(12x10)-----(15x10)----------(20x10)
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If I were making the ammo as a manufacturer, I'm pretty sure I would have tested and modified the amount of "powder" in the tracer rounds to make up for it as much as possible...
"...until I found out that I couldn't make various types of rounds with different components, with different weights, the exact same size and ballistics because the laws of physics stubbornly refuse to bend to my will."
You're suggesting they changed the length of the tracer round with that theory. I've never seen an ammunition belt that looked like an EKG chart.
If the two didn't fly the same path, what would be the point?
Because they believed it was better for accuracy than nothing at all.
(Those clever fellas back in the science lads figured out a way to get those pesky tracer rounds to fly the same path as the ball, the ap, the api, etc. That's why you have different types of tracer. They weigh the same with whatever they're belted with.)
Not so clever of a theory.
I doubt the people who designed the rounds know less than you do or that they sent guys to war with tracers that nowhere near where the rest of the bullets are going.
"THEY" didn't send anyone to war, the US military did. You seriously overestimate Uncle Sam's record for "quality in the field."
No one said they were nowhere near, they said "not the same." Tracers were not as accurate or as effective as ball or AP.
quote author=nrshida link=topic=351311.msg4645336#msg4645336 date=1374216506]
I'd have thought the solution is obvious - make every round a tracer. There might be a benefit to a mass-diminishing round as the velocity reduces :)
[/quote]
Sarcasm I trust.
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"...until I found out that I couldn't make various types of rounds with different components, with different weights, the exact same size and ballistics because the laws of physics stubbornly refuse to bend to my will."
You're suggesting they changed the length of the tracer round with that theory. I've never seen an ammunition belt that looked like an EKG chart.
Because they believed it was better for accuracy than nothing at all.
Not so clever of a theory.
"THEY" didn't send anyone to war, the US military did. You seriously overestimate Uncle Sam's record for "quality in the field."
No one said they were nowhere near, they said "not the same." Tracers were not as accurate or as effective as ball or AP.
quote author=nrshida link=topic=351311.msg4645336#msg4645336 date=1374216506]
I'd have thought the solution is obvious - make every round a tracer. There might be a benefit to a mass-diminishing round as the velocity reduces :)
Sarcasm I trust.
The tracer rounds weighed more than the ball or HE rounds.
They were not shorter or longer but comprised of varying amounts of a few compounds to arrive at the different weights.
As far as how they fly, I am relaying my dad's experience in shooting thousands of rounds from a real plane in real combat conditions.
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"...until I found out that I couldn't make various types of rounds with different components, with different weights, the exact same size and ballistics because the laws of physics stubbornly refuse to bend to my will."
You're suggesting they changed the length of the tracer round with that theory. I've never seen an ammunition belt that looked like an EKG chart.
Because they believed it was better for accuracy than nothing at all.
Not so clever of a theory.
"THEY" didn't send anyone to war, the US military did. You seriously overestimate Uncle Sam's record for "quality in the field."
No one said they were nowhere near, they said "not the same." Tracers were not as accurate or as effective as ball or AP.
Muzik has the right of it here. We're not talking about sniper level accuracy, we're talking about mass produced military ammunition in the 1940s.
Just for grins I ran the ballistics through a calculator for .50 API, Ball, and M1 Tracer using values from a quick google. Unfortunately I couldn't find a ballistic coefficient or bullet weight for the Tracer, but the MV was around 300fps slower than the API or ball.
Ball- Ballistic Coefficient 0.67 weight 647 gr muzzle velocity 2930
API- Ballistic Coefficient 0.65 weight 622.5 gr muzzle velocity 3050
Tracer- Ballistic Coefficient 0.65 weight 643 gr muzzle velocity 2700
The tracer bullet weight is fudged a bit because the only weight I could find for it was an overall round weight. It was 21 grains heavier than the API on that chart, so that's what I went with. I just threw in the API ballistic coefficient because I'd expect it to be more similar to that than ball.
At 600 yards, bullet drop was as follows:
Ball- 70 inches
API- 64.3 inches
Tracer- 83.1 inches
Difference: 18.8 inches
At 300 yards, it was:
Ball- 10.9 inches
API- 9.8 inches
Tracer- 13.1 inches
Difference: 3.3 inches
On vehicle size targets and given all the other variables, the differences are well within normal dispersion. Tailgunning at long ranges, I could see knowing the tracers have a slightly different flight path being a benefit, but when it comes to forward firing MG's on aircraft at typical gunnery ranges, it's just not that huge of a factor.
Wiley.
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Muzik has the right of it here. We're not talking about sniper level accuracy, we're talking about mass produced military ammunition in the 1940s.
Just for grins I ran the ballistics through a calculator for .50 API, Ball, and M1 Tracer using values from a quick google. Unfortunately I couldn't find a ballistic coefficient or bullet weight for the Tracer, but the MV was around 300fps slower than the API or ball.
Ball- Ballistic Coefficient 0.67 weight 647 gr muzzle velocity 2930
API- Ballistic Coefficient 0.65 weight 622.5 gr muzzle velocity 3050
Tracer- Ballistic Coefficient 0.65 weight 643 gr muzzle velocity 2700
The tracer bullet weight is fudged a bit because the only weight I could find for it was an overall round weight. It was 21 grains heavier than the API on that chart, so that's what I went with. I just threw in the API ballistic coefficient because I'd expect it to be more similar to that than ball.
At 600 yards, bullet drop was as follows:
Ball- 70 inches
API- 64.3 inches
Tracer- 83.1 inches
Difference: 18.8 inches
At 300 yards, it was:
Ball- 10.9 inches
API- 9.8 inches
Tracer- 13.1 inches
Difference: 3.3 inches
On vehicle size targets and given all the other variables, the differences are well within normal dispersion. Tailgunning at long ranges, I could see knowing the tracers have a slightly different flight path being a benefit, but when it comes to forward firing MG's on aircraft at typical gunnery ranges, it's just not that huge of a factor.
Wiley.
So, why not run the numbers with the proper tracer rounds?
M20 is the API-T and M21 is the air combat load tracer round.
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The tracer I was using was the stats for the M1 tracer.
I don't seem to be able to find a bullet weight, muzzle velocity, or BC for the M21. The M20 drops the same as the M8 API.
Really, it's a mountain out of a molehill.
Wiley.
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From the 1945 manual of the Browning .50 cal fixed and aircraft.
Testing with 36in bbl.
M2 AP 2840fps 1.38sec to 1000yds. Elevation 35. round weight = .26lb
M8 API 2950fps 1.40sec to 1000yds. Elevation 30. Round weight = .26lb
M20 APIT 2950fps 1.40 to 1000yds. Elevation 30. Round weight = .26lb
Dim trace to 300 and bright trace to 1750.
M1 TR 2900fps 1.366sec to 1000yds. Elevation 35. Round weight = .25lb.
Traces to 1800yds.
(M1 Limited to use in ground machineguns in the continental U.S. and training. )
M10 TR 2900fps 1.366sec to 1000yds. Elevation 35. Round weight = .25lb.
Dim trace to 150, bright to 1900.
M17 TR 2900fps 1.366sec to 1000yds. Elevation 35. Round weight = .25lb.
Traces to 2450yds.
From the 1942 manual of the Browning .50 cal fixed and aircraft.
Testing with 36in bbl.
M2 AP 2900fps
M1 TR 2830fps
M1 I 2830fps
From AAF 1945 Gun Harmonizing Manual tables, all AAF fighters.
ANM2 Aircraft, Basic
M2 AP 2700fps
M8 API 2870fps
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The tracer rounds weighed more than the ball or HE rounds.
Probably because the tracer charge weighed more than the gun powder. Not sure what the differences in lead or shell size were.
They were not shorter or longer
Because???? ...You cannot put different size rounds in the same MG belt!!
comprised of varying amounts of a few compounds to arrive at the different weights.
Exactly. You cannot make two shells the same size and weight but with different materials unless the components in both shells JUST SO HAPPENED to have the same weights.
They did not have a tracer charge that also worked as a propellant to make up for the displaced gun powder. Less powder, less projectile range. To make that projectile go the same distance as other rounds you would have to add more powder. More powder means longer rounds, more brass. Now you have short ball rounds and long tracer rounds.
If they could have made the various rounds perform the same and be the same size they would have.
They couldn't and they knew it so they compromised. They traded a little accuracy and hitting power for what they assumed was better shooting ability for inexperienced or less talented shooters. And if that turned out to be the case most of the time, then it was a good trade off.
As far as how they fly, I am relaying my dad's experience in shooting thousands of rounds from a real plane in real combat conditions.
Sorry, I don't know your dads experience. But with all due respect to his service and experience, science has come a LONG way since the 40s. Many people go their whole lives believing everything they learned even after new research proves old beliefs wrong.
Not all of what people or servicemen were taught was accurate in retrospect. Plus, people forget or fail to consider other explanations for what they see.
For example, if your dad did mostly ground attack where the guns are pointed downward, the "flat trajectory" he experienced may be simply explained by the fact that a tracer traveling at a downward angle is not going to drop as dramatically as one fired straight out. Gravity assisted energy retention.
If he fired on aircraft in a downward manner, same principle.
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The projectile size can vary provided that while a longer projectile is further inside the casing there is still room for correct amount of powder. If there isn't, it will result even in drastically smaller MV or even feed failures if the gun is of blow-back type -as e.g. MG-FF. But that also depends on how much filling there is in the first place and what kind of powder is used (burn velocity). If the casing is already full with powder and a longer projectile needs to be inserted lower MV needs to be accepted or the powder changed to faster burning type, provided it is available and that the gun can stand it.
Compare e.g. MG151/20 AP and MG where the projectile size is vastly different. The MG is inserted just further inside the casing.
The ammunition in belt have to be near same length, of course, or else there is a possibility of feed error. Some gun configurations are more prone to jam if the ammo is even slightly longer that that allowed but that also depends on the feed system and how much recess there is in the barrel mouth to insert the projectile. I'm not sure if any gun system or feed system will not accept a round that has the projectile inserted slightly too deep inside the casing.
-C+
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The rounds in question from WW2.
M1 T
M2 AP
M8 API
M20 APIT
These .50 cal cartridge had to meet an OAL of 5.45in to be fired from all browning .50 cal used by US forces in WW2. What differed was the length and cross section of the bullet between types and the powder used in response.
Tracer only rounds were flat bottom Spitzer along with the M2 AP. M8 API and M20 APIT were boat tail. From the crimp band to the ogive tip, the length was the same. Not from the crimp band aft. Flat bottom spritzer did not have the same long distance stability as boat tail.
M1 T --- Bullet OAL = 2.40
M2 AP -- Bullet OAL = 2.40
M8 API ---- Bullet OAL = 2.31
M20 APIT - Bullet OAL = 2.31
Different powders were shaped differently allowing looser or tighter packing. Or their chemical composition allowed less to be used to achieve the required pressure for the InitV.
Inside of 2000ft(666yd) the ballistic differences between tracer and AP rounds is meaningless to the expected 4Mil dispersion circle or 8ft. AAF testing showed past 2000ft, fighter gunnery was not effective in air combat between moving aircraft to make shooting worthwhile. At 3000ft(1000yd) your 4Mil dispersion circle becomes 12ft or probably worse in reality. Even the crew gunners handbook for the AAF\Navy tells gunners to wait for 600 yards.