Civettone
Tech Sergeant
I disagree. Aren't most fighter vs fighter engagements fought at close range? Isn't it more important to have a high MV when engaging enemy bombers so you can hit the target while staying away from their defensive guns?
Kris
Best Fighter III
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Kris
The purpose of high velocity in the context of explosive rounds is to reduce time of flight.
There are two variables involved in time of flight. (1) distance (2) velocity
You lead your target based on where you estimate it will be when the anticipated distance is closed.
If the distance is such that the flight time is .75 seconds, that means your target has .75 seconds from the moment you pull the trigger to reorient his flight path or there will be a connection. If the velocity is lower, the time of flight might be an extra .25 second which can make a big difference when your target is attempting to evade.
Bombers don't engage in very effective evasive manuevering and thus time of flight is not as important. Destructive impact is, however, very important as you are talking about multi-engined aircraft that can take a lot more hits than a fighter. It just so happens that a heavy projectile like that of the Mk. 108 requires too much case capacity and has too much recoil to increase it's velocity to that of a higher velocity 20mm or .50 cal. and it's destructive ability is achieved without high velocity.
There are two variables involved in time of flight. (1) distance (2) velocity
You lead your target based on where you estimate it will be when the anticipated distance is closed.
If the distance is such that the flight time is .75 seconds, that means your target has .75 seconds from the moment you pull the trigger to reorient his flight path or there will be a connection. If the velocity is lower, the time of flight might be an extra .25 second which can make a big difference when your target is attempting to evade.
Bombers don't engage in very effective evasive manuevering and thus time of flight is not as important. Destructive impact is, however, very important as you are talking about multi-engined aircraft that can take a lot more hits than a fighter. It just so happens that a heavy projectile like that of the Mk. 108 requires too much case capacity and has too much recoil to increase it's velocity to that of a higher velocity 20mm or .50 cal. and it's destructive ability is achieved without high velocity.
Civettone
Tech Sergeant
What differences are we talking about here? If the MK 108 shell takes 0.5 second to cross 250 meters than the MG 151 shell takes 0.35 seconds. Yeah, that's gonna make the difference!
Kris
Kris
"What differences are we talking about here?"
Well, it cuts down on the distance you must lead your target and forces your opponent to react faster. To use your example of a .15 second difference, that can easily be the difference between your engine taking a hit or the round striking two feet further away for a clean miss. I can't give you time to distance figures as it depends on the shape of the cartridge, sectional density and starting velocity. That being said, I have read that the time of flight for the US M.50 is .62 seconds to 500 yards.
I can tell you that as for starting velocity, I have seen the following figures listed for the Mk. II Hispano and Mk. 108. (From Tony Williams' website)
ANTI-TANK AND HEAVY MACHINE GUN CARTRIDGES UP TO 19 MM CALIBRE
30 MM CALIBRE CARTRIDGES
Hispano Mk. II - 880 m/s
Mk. 108 - 505 m/s.
If we accept the above, we can see that right out of the gate, the 20mm is 74% faster than the 30mm.
Perhaps someone will have actual time to distance figures for us to chew on.
Well, it cuts down on the distance you must lead your target and forces your opponent to react faster. To use your example of a .15 second difference, that can easily be the difference between your engine taking a hit or the round striking two feet further away for a clean miss. I can't give you time to distance figures as it depends on the shape of the cartridge, sectional density and starting velocity. That being said, I have read that the time of flight for the US M.50 is .62 seconds to 500 yards.
I can tell you that as for starting velocity, I have seen the following figures listed for the Mk. II Hispano and Mk. 108. (From Tony Williams' website)
ANTI-TANK AND HEAVY MACHINE GUN CARTRIDGES UP TO 19 MM CALIBRE
30 MM CALIBRE CARTRIDGES
Hispano Mk. II - 880 m/s
Mk. 108 - 505 m/s.
If we accept the above, we can see that right out of the gate, the 20mm is 74% faster than the 30mm.
Perhaps someone will have actual time to distance figures for us to chew on.
A slight difference in time of flight doesn't mean much if its reaction time we're talking about, cause nomatter how quick you can't dodge a bullet which is already sent your way - however in fighter vs fighter combat a lower MV means you need higher deflections in order to obtain a hit, and this can prve a problem.
Ofcourse the MK-108 wasn't useless as a fighter vs fighter armament, all you needed was to land one hit, but it wasn't ideal either. And I think had Hitler allowed it to be used as a fighter frm the start as it was intended the armament would've changed from four Mk-108's to maybe four MG-151/20 or the high velocity 15mm MG-151 which was idea for the role.
Ofcourse the MK-108 wasn't useless as a fighter vs fighter armament, all you needed was to land one hit, but it wasn't ideal either. And I think had Hitler allowed it to be used as a fighter frm the start as it was intended the armament would've changed from four Mk-108's to maybe four MG-151/20 or the high velocity 15mm MG-151 which was idea for the role.
"A slight difference in time of flight doesn't mean much if its reaction time we're talking about"
Agreed. I don't think anyone was talking about reaction time though. Reaction time would be the lapse in time between first perceiving a threat and actually moving a flight control in evasive response thereto. Moreover, any lag in the aircraft's orientation after moving the flight control would need to be factored in as well.
For example, let's say a chase pilot fires based on where he anticipates the lead plane will be when the cannon round closes the distance. If the lead pilot tries to react only after perceiving the chase pilot's firing (reaction time), then as you said, it would be difficult to see how he would be able to escape.
If, however, a lead pilot is just doing his darndest to outmanuever a chase pilot, the lead pilot could apply force on his controls the tiniest moment after a cannon round is fired as a result of a decision to do so before the cannon round was fired and as a result, not be hit as a result of the movement of the aircraft during the 1/3 or 1/2 second time of flight for the projectile. Extending the time of flight even .15 seconds potentially could result in right angle movement of a few or even several feet and result in a miss where otherwise, there would be a hit. Obviously, if the extended flight time were 1/3 of a second ... (you get the point).
As a result, we have both errors of lead distance and unanticipated movement after firing that come into play as a result of a longer time of flight due to slow velocity along the flight path.
Agreed. I don't think anyone was talking about reaction time though. Reaction time would be the lapse in time between first perceiving a threat and actually moving a flight control in evasive response thereto. Moreover, any lag in the aircraft's orientation after moving the flight control would need to be factored in as well.
For example, let's say a chase pilot fires based on where he anticipates the lead plane will be when the cannon round closes the distance. If the lead pilot tries to react only after perceiving the chase pilot's firing (reaction time), then as you said, it would be difficult to see how he would be able to escape.
If, however, a lead pilot is just doing his darndest to outmanuever a chase pilot, the lead pilot could apply force on his controls the tiniest moment after a cannon round is fired as a result of a decision to do so before the cannon round was fired and as a result, not be hit as a result of the movement of the aircraft during the 1/3 or 1/2 second time of flight for the projectile. Extending the time of flight even .15 seconds potentially could result in right angle movement of a few or even several feet and result in a miss where otherwise, there would be a hit. Obviously, if the extended flight time were 1/3 of a second ... (you get the point).
As a result, we have both errors of lead distance and unanticipated movement after firing that come into play as a result of a longer time of flight due to slow velocity along the flight path.
SpitfireKing
Airman 1st Class
Sorry If I'm a bit lost.... So what's the topic now?
Wespe
Airman 1st Class
Hi guys, as you can see I am new on this forum
Well to change from four Mk-108's to maybe four MG-151/20 or the high velocity 15mm MG-151, wouldn't have been a problem, if the Lw would have decided so.
As for my believe the best piston engined fighter in WWII was the F4U-4
the best fighter overall Me-262
Well to change from four Mk-108's to maybe four MG-151/20 or the high velocity 15mm MG-151, wouldn't have been a problem, if the Lw would have decided so.
As for my believe the best piston engined fighter in WWII was the F4U-4
the best fighter overall Me-262
Welcome Wespe.
And about MV and its importance in fighter vs fighter combat, well as both me and Jank have explained a lower MV means higher deflections, which can prove a problem because the longer the distance the higher the deflection you will need. And depending on the MV of the round, if its too low you might not be able to see your target.
And about MV and its importance in fighter vs fighter combat, well as both me and Jank have explained a lower MV means higher deflections, which can prove a problem because the longer the distance the higher the deflection you will need. And depending on the MV of the round, if its too low you might not be able to see your target.
Wespe
Airman 1st Class
Hi Soren, thanks for the welcome
Just as I said, if the MG-151/20 or the high velocity 15mm MG-151, would have been better, no problem the Lw could have changed it any time.
But sitting in a plane and being straffed by 4x30mm from 150-300m, if in target the guy would be a goner anyway. Indeed the 262 was supposed to be fitted with MG-151/20 but I think it was Hitler who wanted the 30mm.
But besides this american comment, (They had to pick on something
I never came across any news of a Lw pilot referring to this as a problem in respect to the Me-262. Probably they were so delighted about this awesome plane, that they couldn't be bothered about high or low velocities.
"Long live the Me-262"
Just as I said, if the MG-151/20 or the high velocity 15mm MG-151, would have been better, no problem the Lw could have changed it any time.
But sitting in a plane and being straffed by 4x30mm from 150-300m, if in target the guy would be a goner anyway. Indeed the 262 was supposed to be fitted with MG-151/20 but I think it was Hitler who wanted the 30mm.
But besides this american comment, (They had to pick on something
I never came across any news of a Lw pilot referring to this as a problem in respect to the Me-262. Probably they were so delighted about this awesome plane, that they couldn't be bothered about high or low velocities."Long live the Me-262"
SpitfireKing
Airman 1st Class
Hello Wespe. I won't be contributing to this thread much, considering that's not a topic I know well. Enjoy.
Wespe
Airman 1st Class
Hi SpitfireKing
well, do you need to be an expert to forward your favorite plane in this thread?
Since you display a Spit as your avatar; please feel free to say: I would say the best plane was a S......... .
And I could say;
nooooo way, and there goes the discussion
well, do you need to be an expert to forward your favorite plane in this thread?
Since you display a Spit as your avatar; please feel free to say: I would say the best plane was a S......... .
And I could say;
nooooo way, and there goes the discussion
Civettone
Tech Sergeant
Again on the MK 108, I think it also depends on the way you fight your battles. If you get in close, the MK 108 is the best there is.
But let's use the example of a dogfight at where the enemy aircraft makes a violent evasive manoeuvre and the German aircraft is forced to use deflection. I don't know what it will mean but here goes...
If the aircraft flies at 150 m/s the MK 108 shell will leave at a speed of 650 m/s. A MG 151/20 at 875 m/s.
Let's say the target is 325m away it will take the shell half a second to get there. However, in that half second the target will be 75m further away, so that's another 0.1sec, and in that fraction the aircraft is yet again a bit further, but in any case, it will probably be less than 0.65 of a second. In comparison the MG 151/20 can do 325m in 0.37sec and will catch the enemy in 0.45 sec. So that's 2/3 of the time for the MK 108.
But with a banking aircraft the German aircraft will approach the enemy aircraft faster than in a straight-ahead-tailchase. So then the target will move away at a speed of for instance 100 m/s instead of a 150. Then the MK would reach the target in 0.55 seconds and the MG in 0.43 seconds.
If we half the distance (so 162 m) the difference between both scenarios becomes even less and will be around 0.3 seconds for the MK and 0.2 seconds for the MG.
I concur that even the smallest difference could result in defeat or victory. So then it comes down to the range you shoot down aircraft. German doctrine stressed short distance and the best German pilots preferred to get close to their target ... though there are exceptions.
And then there's also the matter of when the enemy aircraft will break away. If it breaks away at 325 meters, the German aircraft has sufficient time to react and get on its tail again while a fighter breaking at a closer distance has more chance of getting away though of course he would also have a longer exposure time. But in both cases, there is relatively little reason to shoot at the enemy fighter 325 meters away.
So overall, given the obvious advantage of the MK 108 in destructive power I don't see any reason why I would ever use the MG 151 when I can go for the MK. In any case, I will never agree that the MK 108 wasn't suited for fighter vs fighter combat.
Kris
But let's use the example of a dogfight at where the enemy aircraft makes a violent evasive manoeuvre and the German aircraft is forced to use deflection. I don't know what it will mean but here goes...
If the aircraft flies at 150 m/s the MK 108 shell will leave at a speed of 650 m/s. A MG 151/20 at 875 m/s.
Let's say the target is 325m away it will take the shell half a second to get there. However, in that half second the target will be 75m further away, so that's another 0.1sec, and in that fraction the aircraft is yet again a bit further, but in any case, it will probably be less than 0.65 of a second. In comparison the MG 151/20 can do 325m in 0.37sec and will catch the enemy in 0.45 sec. So that's 2/3 of the time for the MK 108.
But with a banking aircraft the German aircraft will approach the enemy aircraft faster than in a straight-ahead-tailchase. So then the target will move away at a speed of for instance 100 m/s instead of a 150. Then the MK would reach the target in 0.55 seconds and the MG in 0.43 seconds.
If we half the distance (so 162 m) the difference between both scenarios becomes even less and will be around 0.3 seconds for the MK and 0.2 seconds for the MG.
I concur that even the smallest difference could result in defeat or victory. So then it comes down to the range you shoot down aircraft. German doctrine stressed short distance and the best German pilots preferred to get close to their target ... though there are exceptions.
And then there's also the matter of when the enemy aircraft will break away. If it breaks away at 325 meters, the German aircraft has sufficient time to react and get on its tail again while a fighter breaking at a closer distance has more chance of getting away though of course he would also have a longer exposure time. But in both cases, there is relatively little reason to shoot at the enemy fighter 325 meters away.
So overall, given the obvious advantage of the MK 108 in destructive power I don't see any reason why I would ever use the MG 151 when I can go for the MK. In any case, I will never agree that the MK 108 wasn't suited for fighter vs fighter combat.
Kris
Wespe
Airman 1st Class
Great, so we both agree that the MK 108 wasn't a problem to the Lw pilots flying the 262. Just pure American envy on the worlds best plane
SpitfireKing
Airman 1st Class
Wel, I've already got shot a million time by everyone. So I kinda fell back. I'm just waiting for an oppotune moment to strike.
Wespe
Airman 1st Class
Thanks for the warning, I will keep my head down, when you start to unleash the qualities of the Spitfire
Wespe
Civettone
Tech Sergeant
Also rare to see an American praising the Spit.
Kris
Kris
Wespe
Airman 1st Class
Hi everybody! I just joined in today. The Mk-108 cannon has a low muzzle velocity, in my opinion that translates to short range and therefore the Luftwaffe pilots would have had to get closer to their target in order to land some hits. As far as I know, the Mk-108 is a 30-mm gun or cannon and it should have been very devastating against the fellow at the business end of its barrel. But like I stated the Lw pilots would have to get real close to hit their target. Maybe a 20-mm cannon through the propeller hub and two 15-mm MG-151 machine guns in the engine cowling of a Bf-109 would have been better. What do you think?
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