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MisterMark
09-04-2008, 11:57 PM
Not a physics wiz so would like to know if your plane is in a dive going 550kph and you fire your guns, are your bullets traveling with more velocity than if you fired your guns at 200kph in level flight?

Does the velocity of the bullets in Il2 have a direct relationship to damage done to a target plane? Reason I ask is because it seems when I park on a bandits six and we are going more or less the same speed, the bandit can absorb a lot of damage before going down even at close range. However, if I dive down in a BnZ attack, it seems only a short burst will do some major damage. Is this because of higher velocity bullets or because of a steeper angle of attack in a dive which usually yields more exposure of the vulnerable areas of the target plane?

Thoughts please.

MisterMark
09-04-2008, 11:57 PM
Not a physics wiz so would like to know if your plane is in a dive going 550kph and you fire your guns, are your bullets traveling with more velocity than if you fired your guns at 200kph in level flight?

Does the velocity of the bullets in Il2 have a direct relationship to damage done to a target plane? Reason I ask is because it seems when I park on a bandits six and we are going more or less the same speed, the bandit can absorb a lot of damage before going down even at close range. However, if I dive down in a BnZ attack, it seems only a short burst will do some major damage. Is this because of higher velocity bullets or because of a steeper angle of attack in a dive which usually yields more exposure of the vulnerable areas of the target plane?

Thoughts please.

M_Gunz
09-05-2008, 02:15 AM
Consider where is the armor and structure of the target?
I once asked about Tu engine pods from behind, answer was posted pictures of gear in the same
pods right behind the engine... doh!

Shoot from deflection and fewer hits chance much better results.

Why did Germans intercept B-17's from the front as tactic? Because it worked better.

And yes, as it's been stated the relative velocities of projectile and target as well as angle
of impact are used. Once hit though the shot continues straight only and modules hit are overall
strength so one big part can absorb damage that really would have pierced through, the old I-16
was one good example but has been changed.

Vinnie_Gumbat
09-05-2008, 03:08 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MisterMark:
Not a physics wiz so would like to know if your plane is in a dive going 550kph and you fire your guns, are your bullets traveling with more velocity than if you fired your guns at 200kph in level flight?

Does the velocity of the bullets in Il2 have a direct relationship to damage done to a target plane? Reason I ask is because it seems when I park on a bandits six and we are going more or less the same speed, the bandit can absorb a lot of damage before going down even at close range. However, if I dive down in a BnZ attack, it seems only a short burst will do some major damage. Is this because of higher velocity bullets or because of a steeper angle of attack in a dive which usually yields more exposure of the vulnerable areas of the target plane?

Thoughts please. </div></BLOCKQUOTE>

In real life it's simple addition.
400mph is 587 fps (feet per second).
So a P-47 diving at 400mph on a tank, firing it's ,50's with a muzzle velocity of 3060fps
will get a net velocity of 3647 fps effective muzzle velocity.

That should be enough to punch a hole in 2" of steel in a square on hit depending on distance to target.

Also in a head on pass, add the velocity of the oncoming aircraft.

Again, it's simple addition as long as velocity loss to air drag is not figured in.

Vinnie

general_kalle
09-05-2008, 05:59 AM
is that the reason why a 37mm cannon on a stuka can do alot of damage to a T43 while a 37mm cannon on the ground doesn't really harm the tank?

and also because it hit's the top which is less armoured i know...

Outlaw---
09-05-2008, 08:21 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by general_kalle:
is that the reason why a 37mm cannon on a stuka can do alot of damage to a T43 while a 37mm cannon on the ground doesn't really harm the tank?

and also because it hit's the top which is less armoured i know... </div></BLOCKQUOTE>

The lighter armor on the top probably has more to do with it but, kinetic energy increases with the SQUARE of the velocity so if you increase the velocity by 10% you increase the kinetic energy by 21%. With a low velocity cannon even a fairly slow 150mph could easily add 10%-15% more KE.

--Outlaw.

MisterMark
09-05-2008, 09:02 AM
So then I suppose the answer in real life is both higher bullet velocity and higher deflection angle (unless head on) yield more devastating damage? But I'm still unclear... does Il2 model the relationship between higher bullet velocity and higher impact damage?

GIAP.Shura
09-05-2008, 09:47 AM
Definitely, no matter how good a shot you are you will never down a 109 from 1 km out using 303s because the bullets are losing their kinetic energy.
However, there are a few things about your argument so far. Technically, higher deflection angle doesn't really affect the velocity of the bullet because the deflection angle is relative to your target, not the ground and deflection angles increase in all directions (vertically and horizontally) from the target's 6 if you understand what I mean. Although, I am guessing you were just meaning attacking a level target and comparing a level attack as opposed to a diving attack. Deflection shots can expose more vulnerable parts to fire but even a very limited deflection shot will provide this advantage.

However, I would say that the additional velocity advantages of firing while diving compared to firing while level or even climbing are pretty negligible when shooting down fighters. Getting the shots on target is the main difficulty, not getting them to do damage. Much more important for devastating damage is to be firing in a shorter range so shots are more likely to hit and be concentrated in a certain area.

M_Gunz
09-05-2008, 09:55 AM
Higher true air muzzle velocity means higher air drag at the same altitude on the bullet
slowing it down a bit quicker. Bullets lose a lot of speed in not a lot of time.

Depending on altitude they lose speed faster or slower too. Air gets thinner with altitude
and humidity/dust in air also affects drag.

That shot from high up at the tank down there 500-1000m away may not hit as hard as one from
a stationary gun 50-100m away from on top of a steep hill.

And forget about gravity assist speeding up the bullet, in one full second straight down it
only adds less than 10m/sec to the velocity while in the same second drag scrubs 100's of
m/s from the same.

M_Gunz
09-05-2008, 10:07 AM
Draw some lines on paper and see the higher your angle off the tail of your target is, the
higher your relative velocity to the same target is for the same speed for you and the target
unless the target is stationary.
Example: if I am at dead six with same speed then our relative speed is zero. If we are at
same speed and I approach from 90 degrees the relative speed is mostly my speed. If we are
coming in head to head the relative speed is our speeds combined.

The thing about shooting upwards or downwards is that it's going to throw off the range at
which the shots cross the sight line which is calibrated with gravity effect on horizontal
shots in mind, at least IRL. It's harder to snipe on steep angle shots.

Vinnie_Gumbat
09-05-2008, 10:40 AM
At effective ranges of small cannon and heavy machine guns gravity assist is negligible.

Air drag is thousands of times greater than any effect by gravity near muzzle velocities.

Where gravity has a great effect is on trajectory. Shooting up or down has a relative effect on
trajectory.

There is no bullet "drop" shooting straight up or straight down.

Vinnie

Blutarski2004
09-05-2008, 01:18 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Vinnie_Gumbat:
At effective ranges of small cannon and heavy machine guns gravity assist is negligible.

Air drag is thousands of times greater than any effect by gravity near muzzle velocities.

Where gravity has a great effect is on trajectory. Shooting up or down has a relative effect on
trajectory.

There is no bullet "drop" shooting straight up or straight down.

Vinnie </div></BLOCKQUOTE>


WW2 50cal M2 AP round
Muzzle Velocity__2835 f/s

Retained Velocity
@ 200 yds_2575 f/s
@ 400 yds_2350 f/s
@ 600 yds_2125 f/s
@ 800 yds_1900 f/s

MisterMark
09-05-2008, 03:26 PM
Well I guess one seemingly simple fact remains... A burst from a BnZ attack is usually more deadly than a near six attack for me as far as my flying and gunnery skills.

M_Gunz
09-05-2008, 06:01 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blutarski2004:
WW2 50cal M2 AP round
Muzzle Velocity__2835 f/s

Retained Velocity
@ 200 yds_2575 f/s
@ 400 yds_2350 f/s
@ 600 yds_2125 f/s
@ 800 yds_1900 f/s </div></BLOCKQUOTE>

What would make that complete is the time to each range or the drop from horizontal boresight.

Funny, in the 1st 200 yds it lost 260 f/s but the loss per 200 yds out to 800 yds is all 225 f/s.
Longer to cross each 200 yds, more drop yet if it's not parabolic then the data must be suspect
or Raaaid may be right about something! Scary http://forums.ubi.com/images/smilies/icon_twisted.gif huh?

Just going by unweighted averages --- so it could be better over the first 200-400 yards
Gravity used is 32.2 ft/s/s.

200 yds in .222 seconds for drop from boresight = 9.5 inches, should be off but not real far
400 yds in .222 + .239 = .461 seconds for drop from boresight = 3 ft 5.1 inches
600 yds in .461 + .274 = .735 seconds for drop from boresight = 8 ft 8.4 inches
800 yds in .735 + .306 = 1.041 seconds for drop from boresight = 17 ft 5.4 inches

edit - hit post button by mistake, finished now, better view of trajectory and timing, drop
relative to sight line depends on where you put the sight line and your convergence range.

M_Gunz
09-05-2008, 06:08 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by MisterMark:
Well I guess one seemingly simple fact remains... A burst from a BnZ attack is usually more deadly than a near six attack for me as far as my flying and gunnery skills. </div></BLOCKQUOTE>

That's because most of the real armor is right behind the pilot, instruments and engine.

Blutarski2004
09-05-2008, 08:08 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M_Gunz:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Blutarski2004:
WW2 50cal M2 AP round
Muzzle Velocity__2835 f/s

Retained Velocity
@ 200 yds_2575 f/s
@ 400 yds_2350 f/s
@ 600 yds_2125 f/s
@ 800 yds_1900 f/s </div></BLOCKQUOTE>

What would make that complete is the time to each range or the drop from horizontal boresight.

Funny, in the 1st 200 yds it lost 260 f/s but the loss per 200 yds out to 800 yds is all 225 f/s.
Longer to cross each 200 yds, more drop yet if it's not parabolic then the data must be suspect
or Raaaid may be right about something! Scary http://forums.ubi.com/images/smilies/icon_twisted.gif huh?

Just going by unweighted averages --- so it could be better over the first 200-400 yards
Gravity used is 32.2 ft/s/s.

200 yds in .222 seconds for drop from boresight = 9.5 inches, should be off but not real far
400 yds in .222 + .239 = .461 seconds for drop from boresight = 3 ft 5.1 inches
600 yds in .461 + .274 = .735 seconds for drop from boresight = 8 ft 8.4 inches
800 yds in .735 + .306 = 1.041 seconds for drop from boresight = 17 ft 5.4 inches

edit - hit post button by mistake, finished now, better view of trajectory and timing, drop
relative to sight line depends on where you put the sight line and your convergence range. </div></BLOCKQUOTE>


..... Hiya, Gunz. I read the data off of a somewhat difficult to read US Army graph. I might have made an error in counting grid sub-increments.

M_Gunz
09-06-2008, 12:02 AM
The shape of that curve....

add: I have such a graph from Butch 2K site, the speed by distance curves are nearly flat over
range 0 to over 800yds and very close to linear over 200yd segments for using linear average
speed.

I also have a plain copy that must have been scanned with high contrast and then shopped a bit
to make all the lines dark, it's very hard to tell the grid in places, just plain hard in others.
Printed blown up and ruler and pen and magnifier I get 2840-2590-2350-2120-1890 f/s at 0,2,4,6,8 x100 f/s.
Without even looking I bet it's very close to yours and from the same chart.

I look and for sure very close. I can't say absolute my grainy resized image is better than
what copy you have and those squares are not only small but slightly uneven in places like he
had to make his own graph paper. Even the cheap stuff we got in the 60's was more regular.

Not exact but then those curves are almost straight, delta v difference by segment is less than 5%.

The real change starts out after 1000 yds, it starts to hold onto speed better more and more once
below 1600 f/s and esp below 1100-1200 f/s, about mach 1.

yards - f/s
============
000 - 2840
diff...--- 250 - avg 2715, .221 sec to strike at 9.4 inches drop from boresight
it lost appx 8.8% of speed, yet the most speed lost
============
200 - 2590
diff...--- 240 - avg 2470, .243 + .221 = .464 sec to strike at 3 ft, 5.6 inches ...
it lost appx 9.3% of speed
============
400 - 2350
diff...--- 230 - avg 2235, .268 + .464 = .732 sec to strike at 8 ft, 7.5 inches ...
it lost appx 9.8% of speed
============
600 - 2120
diff...--- 230 - avg 2005, .299 + .732 = 1.031 sec to strike at 17 ft, 1.4 inches ...
it lost appx 10.5% of speed
============
800 - 1890

There's some idea of times across ranges but *warning*: only ground fire on stationary target.
Fire from a moving plane is subject to added drag due to added TAS and altitude lessening of drag,
and relative speed of shooter and target.
Closing on a target fast whether by higher speed or by path crossing angle acts to reduce time
to target effectively decreasing range. In BnZ I either shoot farther or aim low on target.
It's why you need to pull less lead when you come in with a load of smash. Add deflection and
the effect increases.

OMK_Hand
09-06-2008, 03:28 AM
Hi MisterMark.

Some examples of where to shoot, and why.

http://www.virtualpilots.fi/hist/WW2History-CaptainWind...tTacticsLecture.html

"When you have the faster plane, always go for the rear sector shot, and don't risk a head-on...

Initially climb about 500 meters higher than the enemy, because our planes are faster. During the approach stay right behind the enemy, because visibility to the rear sides is good from both planes.

The approach speed can be quite high. Just before reaching shooting distance, slip to one side, so you'll be able to shoot him slightly from the side. When shooting from dead 6 o'clock of these planes, the pilot armour has often absorbed even the 12.7 mm bullets. (For example W.O. Alho shot his guns empty at a Chaika's pilot armour over the Seiskari Island without any effect. The fuselage skin behind the armour was ripped apart, but the plane didn't go down.) You have to aim well from the start, because the I-16 and Chaika are so manoeuvrable that you can't hit them after they have seen you approach...

All the "pointy-nosed" enemy planes, LaGG-3, MiG-1, MiG-3, YaK-1, Spitfire, and La-5, require almost the same tactics. These all belong to a category of fast and not so manoeuvrable planes (compared to the Brewsters and I16s of the world)... The only way to fight and succeed against these types is to bounce from above. Start shooting only at a very close range... but always try to hit the enemy from his front sides (1-2 and 10-11 O'clock1 ) at low deflection. One hit on the engine from the front is often enough to do some damage and get the engine to malfunction.

When the Pe-2s and YaK-4s (?) started to appear on the front lines, they were too fast for our fighters. The Curtiss Hawk squadron then developed tactics to attack the bombers from the front. That is almost the only tactics against them unless you are able to bounce them from above.

The well-armoured Il-2 requires especially good shooting. The only vulnerable areas of the plane are the top of the canopy and the wing roots, where the armour is thinner. The shooting must be very accurate and thorough, because the effective target area is only about 2 m2. Be careful not to fly in front of this plane after shooting, because it is quite ready to pull up and use it's cannon on you.
For example Sgt. Lehtiö shot at an Il-2 near Koivisto, and made the error of pulling into a shallow climb in front of it. The Il-2 raised it's nose and shot the Brewster down."

Sound general principles?

M_Gunz
09-06-2008, 08:13 AM
If you have to stay behind then better to be 500 ft below and shoot the belly of the plane
up through the engine and cockpit, deflection from below and not affected by The Bar at all.
You can exit behind the target and be headed away before he begins to react if he survives.
Hardest part for me is not colliding with the target from staying on aim too long. I forget
to just sweep and exit, I guess.

OMK_Hand
09-06-2008, 10:08 AM
I was trying my hand at dog fighting, turn-and-burn, a FW190 A4 against an Ace Spitfire V a couple of nights ago, and slightly misjudged my intended 'killer' pass.
Got him now... Oh bugger... Took my own engine out on his tail, and quite possibly shot myself as well.

I recon it was a 'slight misjudgement' because I survived http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif
close-in slashing attacks definitely put those rounds where they do the most good, fighter on fighter.
Got track?

http://www.datafilehost.com/download-fc9b5b47.html

Aaron_GT
09-06-2008, 10:14 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">That should be enough to punch a hole in 2" of steel in a square on hit depending on distance to target. </div></BLOCKQUOTE>

I'd be amazed if it increased penetration by about 150% on an energy increase of 70%.

M_Gunz
09-06-2008, 11:29 AM
By the chart, 1.2" of rolled homogenous armor plate at point blank.
They didn't have the new AP rounds then or relaxed-twist barrels.
Same chart should be floating around, has velocity and penetration for Bullet, AP, Cal 50, M2
It has two speed at range curves, one for 45" barrel and one for 36" barrel.

Highest penetration is at muzzle velocity of the long barrel and shows 1.2".

That Chart's label says RA PD 109333

The one from Butch2K is RA PD 89155 -- pretty much the same, maximum thickness noted is 1.2".
That one is labeled as being from Ballistics Section, Technical Division, 17 Dec, 1943.
It shows penetration of faced hardened plate armor down to the alloy.