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Subject: Modify the B-17 into night bomber/low altatude streak bomber?
45-Shooter    2/14/2013 3:55:59 PM
Given the multiple lines of debate; B-17 Vs Lancaster Vs Mossy, I post the following question; To convert the B-17 from a day bomber into a night/streak bomber, remove the top, bottom and chin turrets, remove the waist and cheek guns and gunners, relocate the flight deck to just behind the bombadier's space so that there is onlythree or four crew! Install large spinners on the props and install a single 20 mm auto-cannon on a flexible "X" bow mount in the plexi nose. Reduction in frontal area, weight and increases in streamlinning make flight both much faster and much more efficient! Since there is room for four 4,000 pound MC bombs in the bomb bay, the shakles should be modified to hold those four heavy bombs if the larger shakle does not fit now. Otherwise eight 2,000 pound bombs should be the standard load. Given the 210-220 knot cruising speed of the Mossy required to make the placard range, the new faster B-17N/S should offer more of everything that makes the Mossy so neat?
 
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oldbutnotwise       6/29/2013 6:03:35 PM
The triggers were solenoids, but as the Browning is a RECOIL operated percussion fired machine gun, then the British must have used THAT principle in the Browning .303 (as they did.)
the triggers on british brownings (303s and 50s) were pneumatic in both  
 
 
No different from the American 12.7mm
 
same end result but for the US preferring electrical over air
 
The Hispano, being gas-operated did require electric priming.
I think you don't understand the subject, the HS404 was percussion just like the browning and 99.9999% of all guns, gas operated was the method for auto cocking the block after a round had fired and nothing to do with the priming electrical priming required a cartridge case that had a electrical element inside it that trigger the round when electricity was applied, rather than a firing pin hitting the percussion cap 
 
 
 
 
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marat,jean       6/29/2013 6:51:01 PM
The Hispano, being gas-operated did require electric priming.
I think you don't understand the subject, the HS404 was percussion just like the browning and 99.9999% of all guns, gas operated was the method for auto cocking the block after a round had fired and nothing to do with the priming electrical priming required a cartridge case that had a electrical element inside it that trigger the round when electricity was applied, rather than a firing pin hitting the percussion cap
 
I understand too well.
 
As does Tony Williams.
 
 
You know what a light strike is? The M2 and M3 did not have enough MASS in the bolt to ensure a proper kinetic hit. Chamber dimensions were part of it, but the bolt did not travel fast enough to hit hard enough to seat and strike the round.
 
Head space error it is called================>
 
 
 
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marat,jean       6/29/2013 6:52:49 PM
There is a firm requirement on the part of the Navy Department for use of 20-mm automatic guns in practically all Navy combat aircraft currently in design and currently designated combat operational aircraft -

The 20-mm automatic guns M2 and M3 in their present stage of development have certain objections and defects which make continued development of this type weapon highly desirable. The following features are considered objectionable and are believed capable of improvement:

(a) The profile of the gun is too bulky for proper installation in VF type wings.

(b) The cyclic rate of the gun is too low.

(c) The belt pull is too low.

(d) It is believed that the over-all weight of the gun and its associated equipments can be materially reduced.

(e) The accumulated tolerances in the manufacture of the weapon are too great to give uniformly efficient operation in these guns.

Other objectionable features which are believed capable of rectification are listed below:

(a) The need to oil the ammunition prior to loading for use in this weapon is undesirable. Self-lubricated ammunition, or the elimination of the need for lubrication, is strongly desired.

(b) The ballistics of the projectile can stand much improvement. It is believed that ballistics similar to that of the Caliber .60 projectile can be closely approximated.

(c) It is believed that an electrically primed round can be developed for the gun which will give more efficient performance.========================>

 
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marat,jean       6/29/2013 6:53:38 PM

(d) The ammunition should be manufactured to fit the chamber of the gun in which it will be fired and not to fit two of these weapons - namely, the American and British 20-mm automatic guns.

From the above, it can be seen that the Navy's need for improvement in the gun and ammunition is immediate and will be continuing until the Army's long range development program of an optimum gun for aircraft materializes. It is understood that the optimum gun will require from 15 to 25 years for development to be completed. Continued improvement in the present cannon will certainly contribute materially in experience gained to the development work leading toward the optimum gun....

Inasmuch as the Chief of Ordnance is definitely interested in this development program, this Bureau wishes to indicate its active interest in and requests that the following program be undertaken:

(a) Improve the present 20-mm Automatic Gun M3 for immediate needs.

(b) Continue development projects of such guns as the 20-mm T32 and T33 to arrive at a reliable lightweight, high performance gun within the next four to six years.

(c) Improve the ammunition for these guns in order to achieve a family of matched projectiles of relatively high performance.

(d) Through the experience gained in this development program obtain information, data and experience which, combined with current gun research for an optimum gun, might materially aid in the development of an optimum gun for aircraft within the next ten to fifteen years.

To support such a program, this Bureau will initiate projects complementary to those undertaken by the Ordnance Department (ASF) to provide competent and experienced personnel and afford Navy Ordnance facilities to assist in the program. In addition, this Bureau will furnish funds to support a proportional part of this development program as established by the estimates of the Chief of Ordnance."

This letter resulted in the cooperation of the Army, with Navy engineering personnel, familiar with the conditions that needed remedying, in solving the various problems. Today, barely five years after the war, every point brought out by the Navy's Chief of the Bureau of Ordnance has been answered. Nothing was basically wrong with the weapon. Its wartime performance, good or bad, was the result of having been bought in desperation, put into mass production without first having been adequately proved, and then modified regularly to meet a future commitment before the previous model had been made to function reliably.

[Chinn goes on to describe the postwar development of the American Hispano, implying that all of the problems were solved within a few years in the much-modified M3 and M24 variants. However, a separate source mentions that when the French received a batch of F8F-1B Bearcat fighters for use in SE Asia in the early 1950s, they found that a high proportion (25 out of 64) of the installed 20 mm M3 cannon were defective, due to parts being outside the specified margins, and had to be replaced].

 
Note the highlighted above. The British got there first.
 
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oldbutnotwise       6/29/2013 7:10:53 PM
The Hispano, being gas-operated did require electric priming.
I  think you don't understand the subject, the HS404 was percussion just  like the browning and 99.9999% of all guns, gas operated was the method  for auto cocking the block after a round had fired and nothing to do  with the priming electrical priming required a cartridge case that had a  electrical element inside it that trigger the round when electricity  was applied, rather than a firing pin hitting the percussion cap   
  
 
I understand too well.
 
As does Tony Williams.
 
 
You know what a light strike is? The M2 and M3 did not have enough MASS in the bolt to ensure a proper kinetic hit. Chamber dimensions were part of it, but the bolt did not travel fast enough to hit hard enough to seat and strike the round.
 
Head space error it is called================>
 
 
which has NO bearing on the thread as we are talking about electrical priming, it is one of the causes of the US guns failing so badly but does not alter the fact that they are percussion ignition guns
 
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oldbutnotwise       6/29/2013 7:13:22 PM
(c) It is believed that an electrically primed round can be developed for the gun which will give more efficient performance.========================>
and pigs might fly, they could have developed an electrical primed round but they didn't and there is nothing to say that an electrical primed round would have worked - its a what if and they can work both ways
 
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marat,jean       6/30/2013 12:27:28 PM
They did and it did. 

 
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oldbutnotwise       6/30/2013 2:04:23 PM
no you are wrong, during WW2 no electrically primed hs404 was produced, the HS404 used by the navy used conventional explosive primers
 
the firing circuit was electrical but the gun itself was not
 
 
 
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marat,jean       7/1/2013 12:08:35 PM
You misunderstand. The cannon to which the American  Navy report ultimately referred was the M61 VULCAN, then in its beginnings.
 
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oldbutnotwise       7/1/2013 4:57:49 PM
Sorry but when did we move from cannons and Mgs fitted to WW2 aircraft to the M61 Vulcan a Gun that has no lineage to any WW2 gun it being a pure clean sheet design
 
my point stands that the HS404 was never electrical primed (the first US electrical primed gun was I believe the M61)
 
as for the Head space issue it was not a case of lack of mass but the gap between the breach block and the cartridge (the head space) was too great when used in a mount that allowed flex, reducing this gap vastly reduced the stoppages
 
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