Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Citabria on June 07, 2002, 03:39:04 AM
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were the 40mm synched to fire at the same time?
or did one fire and then the other?
in ah one fires then the other making the nose ya back and forth and making all 30 rounds miss.
is this right?
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lol
excellenty put! :)
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An interesting question! Wish I knew, maybe Tony will drop in with an answer.
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I did check book "Hawker Hurricane: An Illustrated History" by Francis Mason and there were no mention about synchronization.
btw book has a colour scheme of AH's IId "Z-Zebra" BP188 from No.6 Squadron and colour is more brown than it is in AH.
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Staga,
When ever I encounter the word 'synchronization' ( no I didn't check the spelling ) it makes me think of issues with the propeller. I don't think I've ever seen a mention with any plane book/manual if weapons fired simultaneously, pairs or singleton. Or could that be tuned for example and different planes of same type might have different configurations.
// fats
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I don't think any guns/cannons were synchronized on any WWII planes.
Synchronized to fire through the prop maybe, but they aren't synched to fire together.. but rather to fire when there isn't a blade in the way.
I'd think it would do some evil things to a plane if guns were synched to fire together.
-SW
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Good question... But firing guns that big, if they were sychronized it'd prolly rip the wings off :)
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Hi Citabria,
>were the 40mm synched to fire at the same time?
Excellent question! The Pilot's Notes state that the 40 mm guns were fired electro-pneumatically, opposed to the normal pneumatic system usually employed in British WW2 fighters, so it seems possible.
The benefits would be symmetric recoil without any yawing moment, which could be expected to improve accuracy.
Even for the usual small rapid-fire cannon, synchronized firing would have been beneficial by reducing the recoil-induced vibrations to a simpler oscillation mode (I'd guess :-) In the Fw 190A-8 for example it would have been possible to fire all MG151/20 cannon at once, but I don't know whether it was done, or even whether the synchronized wing root cannon were synchronized with each other, too. From pictures of a Me 109 calibrating the synchronization system, I'd say at least the cowl guns of German fighters fired each shot simultaneously.
Regards,
Henning (HoHun)
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aren't the cannons recoilless?
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Use Preparation H citabria... shuffling your buttcheeks while firing is not a good combination
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If there isn't any special system to force them to fire one after the other the most logical thing is that they fire simultaneously when the trigger is pressed. With both having the same ROF they should also continue firing synchronically.
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Originally posted by HoHun
Hi Citabria,
>were the 40mm synched to fire at the same time?
Excellent question! The Pilot's Notes state that the 40 mm guns were fired electro-pneumatically, opposed to the normal pneumatic system usually employed in British WW2 fighters, so it seems possible.
The benefits would be symmetric recoil without any yawing moment, which could be expected to improve accuracy.
Agreed - in fact the guns were generally fired semi-auto rather than full-auto, because firing pulled the aircraft nose down (not too clever when you were a zero feet...) so the pilot aimed and fired both guns simultaneously, one shot per gun at a time.
I have read that the firing mechanism for the underwing NS-37 cannon used by the Il-2 3M tankbuster was not that good so the guns didn't fire quite together, which caused the plane to sway from side to side.
Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/
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Originally posted by udet
aren't the cannons recoilless?
Definitely not - but they did have a very long recoil movement which kept the peak recoil impulse down to 20mm levels.
Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/
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Tony, would you agree that the current modelling of the cannons on the Hurricane IID is inaccurate then? By your description I would say it is; the amount of recoil is extremely severe and virtually unaimable.
regards
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Hi Tony,
>in fact the guns were generally fired semi-auto rather than full-auto
Do you know whether the mechanism was modified, whether the trigger system was modified, or whether it was up to the pilot to time the trigger pull?
>I have read that the firing mechanism for the underwing NS-37 cannon used by the Il-2 3M tankbuster was not that good so the guns didn't fire quite together, which caused the plane to sway from side to side.
I think free-firing guns generally have a strong variation in rate of fire. I've seen one clip with Stomoviks strafing a target where you can see that one moment both wings' cannon fire simultaneously, and the next moment they fire alternatingly. (I don't know the wing gun calibre, though.)
I know synchronization troubles from my latest hobby - stereo photography :-) With Bowden cable triggers, both cameras hardly ever "fire" simultaneously! I've got to think of an electrical system, like in the Focke-Wulf :-)
Oh, about the Focke-Wulf: If I understood it correctly, the electrical priming system requires a pulse generated by the magneto of the Schußgeber to trigger the gun at all. That means the electically primed wing cannon actually have to fire simultaneously with one of the synchronized guns since it doesn't look as if the Schußgeber in the A-8 is the same as in the previous models and doesn't have a special magneto for the wing cannon.
Regards,
Henning (HoHun)
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I don't mean to butt in, but I think there is more than one aircraft suffering from synchronized firing when it didn't have it.
Point in case: P-38. Didn't the P-38 fire all four 50's at the same time rather than the current synchronized version?
If this is the case, the Hurri needs to be fixed, and I suspect a bunch of other planes too.
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I brought that up a while ago fork and if you fired all 4 guns on a p-51B while having 500 rnds on each gun bank, it'd take (and ill use a fictitious time here, I dont remember the exact times) 5 seconds. At the same time, firing the 38's guns while having 500rnds also took 5 seconds. The odd thing is that in game it seems that if you fire the 51B's guns, each gun bank fires at once, resulting in 2 bullets going out at one time..while the 38 seems to shoot 1 bullet a time. But since its very hard to actually see what guns fire when you press the triggers there's no way to tell for sure. Confused me back then, confuses me now. Headaches.. not worth it ;)
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Originally posted by Replicant
Tony, would you agree that the current modelling of the cannons on the Hurricane IID is inaccurate then? By your description I would say it is; the amount of recoil is extremely severe and virtually unaimable.
I've no idea - I would have to have flown a real IID and then the sim to compare, and I've not done either!
It's important to distinguish between the peak recoil impulse and the total recoil. Obviously, the 40mm round produced several times the recoil of a 20mm, enough to push the plane's nose down with each shot, but the long recoil spread the force out to minimise the stress on the aircraft's structure, so it was a firm push rather than a hard kick.
Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/
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Originally posted by HoHun
Hi Tony,
>in fact the guns were generally fired semi-auto rather than full-auto
Do you know whether the mechanism was modified, whether the trigger system was modified, or whether it was up to the pilot to time the trigger pull?
It was left to the pilot. The RoF was low enough (90-100 rpm) that they presumably just stabbed the fire button for each pair of shots.
Incidentally, they also learned to pull back slightly on the stick just as they fired, to compensate for the nose-down push.
On a typical attack run a IID would fire four pairs of shots, starting at 900 yards and finishing - too close!
Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/