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luftluuver
05-11-2007, 11:11 AM
The 109 had a 50mm blast tube for its 30mm cannon.

Could it happen that a shell could touch the side of the blast tube since there was only a 10mm clearance.

Vike
05-11-2007, 11:14 AM
Originally posted by luftluuver:
The 109 had a 50mm blast tube for its 30mm cannon.

Could it happen that a shell could touch the side of the blast tube since there was only a 10mm clearance.

A better question would be:

Can this tube make a sort of barrel extension for the MK108 and thus permitts an increasing of its effective range? http://forums.ubi.com/groupee_common/emoticons/icon_confused.gif

@+

JG14_Josf
05-11-2007, 11:36 AM
Could it happen that a shell could touch the side of the blast tube since there was only a 10mm clearance.

No; if it did, then, the 'gun' could hardly be called a gun, cannon, rifle, etc.

Sling shot?

Platypus_1.JaVA
05-11-2007, 01:48 PM
10mm is pretty big of a clearance, considered that the shell (30mm) could fit in the barrel (also 30mm) http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

Blutarski2004
05-11-2007, 02:18 PM
I cannot imagine a situation where there would be any realistic risk of a projectile hitting the interior of the blast tube.

The blast tube would not increase the energy of the round.

WWSpinDry
05-11-2007, 02:27 PM
Maybe one of the hard-core physics geeks could calculate the G force that would be needed to cause the path of the aircraft (and hence the tube) and that of the shell to diverge by at least 10mm before the shell were to exit the tube--thus causing a collision. Bonus points if a chart or table is involved.

Blutarski2004
05-11-2007, 03:58 PM
Originally posted by WWSpinDry:
Maybe one of the hard-core physics geeks could calculate the G force that would be needed to cause the path of the aircraft (and hence the tube) and that of the shell to diverge by at least 10mm before the shell were to exit the tube--thus causing a collision. Bonus points if a chart or table is involved.

..... and accomplished in the 2.5 to 3 one thousandths of a second it would take the projectile to travel the length of the blast tube.

;-]

WWSpinDry
05-11-2007, 04:36 PM
Precisely my point. That'd take one big honkin' pull on the stick. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

tigertalon
05-11-2007, 04:52 PM
Originally posted by WWSpinDry:
Maybe one of the hard-core physics geeks could calculate the G force that would be needed to cause the path of the aircraft (and hence the tube) and that of the shell to diverge by at least 10mm before the shell were to exit the tube--thus causing a collision. Bonus points if a chart or table is involved.

That's trivial. t=l/v (t-time shell needs to travel through the blast tube, l-length of blast tube, v-muzzle velocity), I don't know what the length of blast tube is, assuming it's 2 meters, we get the time: t=3,7ms.

Now assuming shell travels perfectly straight after it leaves the barrel, it would take acceleration a=2s/t^2 (s=10mm) to touch the blast tube.

Surprisingly, a=146m/s^2=15g.

ake109
05-11-2007, 07:41 PM
Originally posted by Vike:

Can this tube make a sort of barrel extension for the MK108 and thus permitts an increasing of its effective range? http://forums.ubi.com/groupee_common/emoticons/icon_confused.gif

@+

A definite NO. If _any_ sort of barrel extension were to be screwed on to a Mk108, the result would be gas blowback into the chamber.

The Mk108 came with a very short barrel due to the need for the hot gas to clear the barrel before the bolt moves back. The Mk108 had no delayed blowback, so if the barrel was extended, the projectile would still be in the barrel when the bolt has travelled backwards and the hot gas would enter the chamber.

Xiolablu3
05-11-2007, 08:40 PM
I dont think a longer barrel increases the range, I think it increases accuracy.

And, to increase the accuracy of the weapon, the tube would have to be rifled and be a snug fit with the shell, not have clearance on each side.

tagTaken2
05-11-2007, 08:46 PM
Originally posted by WWSpinDry:
Maybe one of the hard-core physics geeks could calculate the G force that would be needed to cause the path of the aircraft (and hence the tube) and that of the shell to diverge by at least 10mm before the shell were to exit the tube--thus causing a collision. Bonus points if a chart or table is involved.

Raaid?

Little help?

zugfuhrer
05-12-2007, 05:13 AM
If there where any risk for the procectile to hit the sides of the blast tube, i.e differ 10mm in a trajectory of 1-1,5m what would the precision be after 100m? The procejtile would differ at least 25m from the centerline of the barrel.

The lenght of the barrel increase the distance a procectile can accelerate. In theory it increase the muzzle velocity.

But it is not that simple. The powder in the cartridge is adjusted to the lenght of the barrel and the weight of the projectile. The pressure that makes the projectile to accelerate should be so close to constant as possible. It shall burn very precise.

In theory a very very long barrel the procectile would halt inside it.

A long barrel should need a slow burning powder.

As an example, a revolver needs a very fast burning powder, a sniper rifle needs less fast powder.

The recoil is also dependent of the time it takes to accelerate the procectile to its top speed.
I think that the tube would in theory slightly decrease the effective range of the gun, because the projectile would build up a plug of thickerer atmosphere in front of it than it would if there where no tube.

WWSpinDry
05-12-2007, 08:18 AM
Originally posted by tigertalon:
Surprisingly, a=146m/s^2=15g.
Yes, that is surprising. I would have expected the required acceleration to be much greater. Fifteen G is still unattainable in a 109, but ...

I didn't get to see any charts or tables, though. http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif

http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

ake109
05-12-2007, 10:53 PM
Originally posted by WWSpinDry:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by tigertalon:
Surprisingly, a=146m/s^2=15g.
Yes, that is surprising. I would have expected the required acceleration to be much greater. Fifteen G is still unattainable in a 109, but ...

I didn't get to see any charts or tables, though. http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif

http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif </div></BLOCKQUOTE>

Remember its not just the Bf109 pulling 15G. Its 15G instantaneous _after_ the projectile leaves the muzzle of the Mk108.

Vike
05-13-2007, 01:50 AM
Originally posted by Xiolablu3:
I dont think a longer barrel increases the range, I think it increases accuracy.

And, to increase the accuracy of the weapon, the tube would have to be rifled and be a snug fit with the shell, not have clearance on each side.

Interesting http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

By the way,IIRC,there were the ability to disable the MK108-shell self-destruct mecanism,that increased the range a bit! http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

@+

IL2-chuter
05-13-2007, 04:33 AM
Originally posted by ake109:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by WWSpinDry:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by tigertalon:
Surprisingly, a=146m/s^2=15g.
Yes, that is surprising. I would have expected the required acceleration to be much greater. Fifteen G is still unattainable in a 109, but ...

I didn't get to see any charts or tables, though. http://forums.ubi.com/images/smilies/16x16_smiley-sad.gif

http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif </div></BLOCKQUOTE>

Remember its not just the Bf109 pulling 15G. Its 15G instantaneous _after_ the projectile leaves the muzzle of the Mk108. </div></BLOCKQUOTE>

Actually, the Gs may be applied anytime prior to the projectile leaving the muzzle (or before firing, for that matter) as the 15G acceleration on the projectile will cease once it leaves the barrel and continues on the airframe.

Also, though powder burn times can affect different barrel lengths, powder quantity (another "burn time" variable) is a much bigger variable. MK108s have a very small amount of propellent with a corrosponding low muzzle velocity.

Xiolablu3
05-13-2007, 12:29 PM
Originally posted by Vike:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Xiolablu3:
I dont think a longer barrel increases the range, I think it increases accuracy.

And, to increase the accuracy of the weapon, the tube would have to be rifled and be a snug fit with the shell, not have clearance on each side.

Interesting http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

By the way,IIRC,there were the ability to disable the MK108-shell self-destruct mecanism,that increased the range a bit! http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

@+ </div></BLOCKQUOTE>

VIke please dont take this as gospel, I am not 100% sure about it.

You will need to check it.

MEGILE
05-13-2007, 12:41 PM
Originally posted by Blutarski2004:

..... and accomplished in the 2.5 to 3 one thousandths of a second it would take the projectile to travel the length of the blast tube.

;-]

With trim on a slider.... I could do it.

CD_kp84yb
05-13-2007, 02:32 PM
quote
By the way,IIRC,there were the ability to disable the MK108-shell self-destruct mecanism,that increased the range a bit!

End

that is called shell type K (3 cm M-Gesch. o. Zerl.)
In english: type K 3 cm M-shell without selfdestruction.

No need to disable the selfdestruction.

cheers

cheers

Vike
05-14-2007, 01:31 AM
Originally posted by CD_kp84yb:

that is called shell type K (3 cm M-Gesch. o. Zerl.)
In english: type K 3 cm M-shell without selfdestruction.

No need to disable the selfdestruction.

Interesting too! http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

@+

ps:

Don't worry Xiola,lol http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif