WWII Fighter Wing Gun Installations
Charles K. Scott
From Charles...@dartmouth.edu (Charles K. Scott)
In article <1991Sep24.2...@cbnews.cb.att.com>
wma...@STL-06SIMA.ARMY.MIL (Will Martin) writes:
> Were these openings covered with
> fabric that the guns fired through?
Yes
Was this fabric renewed each flight?
Yes
> Why? Did it help the aerodynamics of takeoff?
That wasn't the original intent of the patches. My understanding was
that during the early part of WWII, pilots found that their guns were
freezing at high altitude leaving them vulnerable. The patches were
supposed to keep water out of the breeches of the magazine action
before the guns opened fire. Once a target was in sight and firing
began, the action of the firing was enough to keep the gun from
freezing.
> Was such fabric-covering
> dispensed with as the fighting grew more intense (that is, was it an
> item of maintenance that could be dispensed with when time was pressing)?
I don't think this was dispensed with until a method for heating the
guns was developed. As I mentioned above, the patches kept water out
of the works until the guns opened fire.
> Didn't this fabric ever catch fire, and present a hazard to the plane?
Not to my knowledge.
> 3) Some varieties of fighters have recessed guns, as mentioned above.
> Others have the gun muzzles extending out from the wings quite a bit (a
> foot or more, it appears). Why do one versus the other? Was one style
> characteristically German while the other was characteristically Allied
> (or British, or American)? Or was it something that was a
> designer/manufacturer trait, rather than associated with a country?
> What are the advantages/disadvantages of each approach?
This, I believe, was more a function of attempting to adapt a weapon to
an existing wing then any other factor. For instance, the BF 109
originally was designed to fly with three machine guns. The wing
designed for the fighter had no provision for armament what-so-ever and
when Messerschmidt was asked to install cannon later on, he was hard
pressed to do so. The feed for the cannons went from the breech out to
the wing tip and back again and still wasn't enough to provide for much
firing time. When aircraft were designed with a particular armament in
mind such as the P-47 with it's eight 50 caliber machine guns, the wing
was built around them and they were staggered to allow proper belt
feeding.
> 4) What are the advantages/disadvantages of fuselage-mounted versus
> wing-mounted guns? It would seem that wing mounts would make disposing
> of fired-cartridge cases easier, and less likely to interfere with or
> damage the aircraft, but that fuselage-mounting would allow greater
> ammunition-carrying capacity. Is this correct? Any other points?
The biggest problem with fuselage mounted weaponry was the need to
synchronise them to fire through the propellor disc. This has the
effect of limiting the firing rate a little. You might be correct in
your assumption about the ammo carrying capacity although the pilots
and the engineers differed in their oppinions as to what constituted
enough for a mission. Some wing mounted machine guns carried as much
as was ever packed into the fuselage mounted versions. Again, in the
case of the Messerschmidt, it wasn't the amount of ammo to be carried
that placed the machine guns in the fuselage, but the desire of Herr
Messerschmidt to design the thinnest most aerodynamically clean wing he
could. Most experts I've read say that the marriage of cannon to wing
in the BF 109 was never successfull resulting in unsightly bulges and a
reduction in performance. The cleanest example of the breed is
considered to be the BF 109F which had no wing guns.
Corky Scott
George Patterson
From George.P...@att.att.com (George Patterson)
I can't answer all of these, but I'll tackle the others.
1. Recessed guns were typically covered with fabric patches which were
renewed on landing. The patches kept "dirt-daubers" and other trash
out of the barrels. Firing through a dirt-dauber nest could ruin your
whole day. Covers or plugs were usually used on protruding barrels.
2. Guns were recessed into the wing whenever possible to reduce drag. The
wing has at least one large structural member inside, however, and
sometimes the guns could not be located far enough back. In addition,
with rare exceptions, the shells are fed through a passage in the side
of each gun, and each gun will usually have to be mounted more forward
than its neighbor to allow room for this chute. This usually results
in the guns to the inside of the wing protuding more than thos to the
outside.
3. In a single engined prop-driven aircraft, fuselage mounted guns have
to be synchronized to fire through the prop, resulting in a slower
rate of fire. In any other case, wing mounted guns are generally less
accurate. With wing mounts, there is a range at which all the guns are
targeted together (the "point of concentration"). Closer than this
(or further away) and you get a sort of "shotgun" effect. Depending
on the pilot, this is either a feature or a bug.
In any single engined aircraft, there's usually not a lot of room in
the fuselage for ammo; this is not so much of a problem with a multi.
Let me add a question to the list. We've all seen the "gun camera" films
of a plane being hit and going down in flames - all the way down. Does
this mean that the victorious pilot kept the trigger down until the other
plane crashed, did the camera keep going for a while, or was the camera
controlled by a separate switch?
-----------------------------------------------------------------------
| If you take a dog which is starving and feed him
George Patterson - | and make him prosperous, that dog will not bite
| you. This is the primary difference between a dog
| and a man. Samuel Clemens
-----------------------------------------------------------------------
Jon C. R. Bennett
From "Jon C. R. Bennett" <jb...@andrew.cmu.edu>
wma...@STL-06SIMA.ARMY.MIL (Will Martin) writes:
> From Will Martin <wma...@STL-06SIMA.ARMY.MIL>
> 2) Some fighters have the gun muzzles recessed into the wing, behind the
> leading edge. When these close-up firing pictures are shown, one can see
> bits of fabric around the gun-muzzle-openings in the wings dancing about
> as the gasses from firing rush by. Were these openings covered with
> fabric that the guns fired through?
yes
>Was this fabric renewed each flight?
yes
> Why?
It kept ice from forming in the barrel at high altitude.
> 3) Some varieties of fighters have recessed guns, as mentioned above.
> Others have the gun muzzles extending out from the wings quite a bit (a
> foot or more, it appears). Why do one versus the other?
Guns extending from the wing are usualy the result of one of two things
a) the gun has a very long barrel for balistic reasons (length relates to
accuracy), and because of the type of gun/ammo, cannons often had very
long barrels (different lengths for different muzzel velocities)
b) many guns were placed very close to the same point in the wing for some
reason, so inorder to allow the ammunition to be laid out in the wing
each had to be farther foward then the one next to it.
I
I I <- barrels
I I I
-----------------------------------\
# # # \
=======# # # <- guns \ <- wing
=======# # /
ammo -> =======# /
-------------------------------------/
> 4) What are the advantages/disadvantages of fuselage-mounted versus
> wing-mounted guns? It would seem that wing mounts would make disposing
> of fired-cartridge cases easier, and less likely to interfere with or
> damage the aircraft, but that fuselage-mounting would allow greater
> ammunition-carrying capacity. Is this correct? Any other points?
Wing mounts have the advantage of a clear field of fire, whereas fuselage
mounts must fire through the prop (assuming single engine aircraft). Wing
mounts however make the wing thicker (increases drag) require that the
wing be structural (more weight-> more drag). It is a tradeoff between
aerodynamics and rate of fire, altho in WWI rate of fire usual won (the
dogfight).
jon
imj...@csc1.anu.edu.au
From imj...@csc1.anu.edu.au
In article <1991Sep24.2...@cbnews.cb.att.com>, wma...@STL-06SIMA.ARMY.MIL (Will Martin) writes:
[Questions about gun installations and coverings on WWII aircraft.]
> 1) Am I right in assuming that all these shots of wing-guns firing had
> been taken on the ground?
This is my personal opinion only, but I cannot imagine any pilot going into a
combat situation with the bulky apparatus required to take 'live' shots of the
guns firing. I also think that these shots would have been taken on the
ground. Another reason to believe this is that the amount of vibration induced
by the airstream and also the guns firing would have resulted in shots of
significantly inferior quality to those seen in the films.
> 2) Some fighters have the gun muzzles recessed into the wing, behind the
> leading edge. When these close-up firing pictures are shown, one can see
> bits of fabric around the gun-muzzle-openings in the wings dancing about
> as the gasses from firing rush by. Were these openings covered with
> fabric that the guns fired through? Was this fabric renewed each flight?
> Why? Did it help the aerodynamics of takeoff? Was such fabric-covering
> dispensed with as the fighting grew more intense (that is, was it an
> item of maintenance that could be dispensed with when time was pressing)?
> Didn't this fabric ever catch fire, and present a hazard to the plane?
The gun-port patches where canvas pieces placed over the ports before each
take-off. Their main function was to prevent debris entering the gun-barrel
during take-off. Aerodymnamics may have been improved, but I suspect that this
was only marginal. I don't believe the covers were dispensed with, they just
became less obvious. The weapons that projected forward of the wing (see
below) had small caps that fitted over the end of the barrels and so are much
harder to see in photographs. The patches and caps were replaced by the ground
crew as part of the rearming procedure, which included cleaning of the weapons.
The time required to put the covers on was minimal. From memory, I don't
believe flammability was ever a problem.
> 3) Some varieties of fighters have recessed guns, as mentioned above.
> Others have the gun muzzles extending out from the wings quite a bit (a
> foot or more, it appears). Why do one versus the other? Was one style
> characteristically German while the other was characteristically Allied
> (or British, or American)? Or was it something that was a
> designer/manufacturer trait, rather than associated with a country?
> What are the advantages/disadvantages of each approach?
This is not going to be a comprehensive reply. A rule of thumb is that as the
war progressed the armament became larger (i.e. fired heavier rounds) and so it
became impossible to mount them within the wing. It is essentially the
difference between machine-guns (.303 inch, .5 inch, 7.9 mm) which were typical
in the early part of the war versus cannons (20 mm, 30 mm, 40 mm and bigger)
which became more or less standard armament later. The German Air Force had
many large calibre weapon pods that were mounted externally to the whole wing
(essentially bolted on to the plane) to give their fighters heavier weapons for
use against the Allied bombers.
> 4) What are the advantages/disadvantages of fuselage-mounted versus
> wing-mounted guns? It would seem that wing mounts would make disposing
> of fired-cartridge cases easier, and less likely to interfere with or
> damage the aircraft, but that fuselage-mounting would allow greater
> ammunition-carrying capacity. Is this correct? Any other points?
Again, from memory, so not a authoritative answer, fuselage mounting
allowed heavier weapons to be carried or more rounds for equivalent weapons.
Hitting power was increased because there was no need to harmonize the weapons'
aim to concentrate at some defined point. However, space limitations meant
that fewer weapons could be carried in that position, reducing the weight of
fire. Also reducing the weight of fire was the need to synchronize the firing
of the weapons with the propellor revolution, unless the weapon was fired down
the engine shaft, as done with the bf109-E, for example. This worked, but the
engineering was of course more involved. By the end of the war, the engines in
the fighters were, in general, so large that there was no room for fuselage
mounted weapons. The 109 persisted with them, but the bulges in the cowling
required to carry the machine guns must have affect the performance of the
aricraft.
I hope that this has answer, at least partially, your questions. As this
reply was done from memory, I am sure to have left a lot out.
--------------------------------------------------------------------------------
Ian Jamie Department of Physics
imj...@csc.anu.edu.au Australian Defence Force Academy
i...@phadfa.ph.adfa.oz.au Campbell, Australian Capital Territory, 2600
ja...@rsc.anu.edu.au Australia
DENVER CHUAN-HIN TAM
From dc...@eos.ncsu.edu (DENVER CHUAN-HIN TAM)
> Will Martin <wma...@STL-06SIMA.ARMY.MIL>
>2) Some fighters have the gun muzzles recessed into the wing, behind the
>leading edge. When these close-up firing pictures are shown, one can see
>bits of fabric around the gun-muzzle-openings in the wings dancing about
>as the gasses from firing rush by. Were these openings covered with
>fabric that the guns fired through? Was this fabric renewed each flight?
>why? Did it help the aerodynamics of takeoff? Was such fabric-covering
>dispensed with as the fighting grew more intense (that is, was it an
>item of maintenance that could be dispensed with when time was pressing)?
>Didn't this fabric ever catch fire, and present a hazard to the plane?
>From what I recall, these little pieces of fabric were place there to
cover the gun muzzles so that moisture wouldn't enter the gun and
freeze at high altitude, thereby jammng the gun solid. And yes, I
suppose that it had to be replaced every time the guns were fired.
>3) Some varieties of fighters have recessed guns, as mentioned above.
>Others have the gun muzzles extending out from the wings quite a bit (a
>foot or more, it appears). Why do one versus the other? Was one style
>characteristically German while the other was characteristically Allied
>(or British, or American)? Or was it something that was a
>designer/manufacturer trait, rather than associated with a country?
>What are the advantages/disadvantages of each approach?
I think that it had very little to do with 'style'. If you look at
cut away diagrams of WWII fighters with wing guns, I think almost all
of the guns had ammo boxes laid to the side of the gun. Thus if the
guns were to be closely spaced to ensure a good pattern (or for what-
ever reason was found) There had to be some way of staggering the ammo
feeds to allow the guns to be placed alongside (I guess the best example
of this would be the P-47.) I suggest that you look up such a cut-
away drawing, it would show the layout better than I can describe.
Sometimes also I guess that the guns were too big to fit completely
inside the wing and had to protrude (Like the 20mm cannon in the
British fighters).
>4) What are the advantages/disadvantages of fuselage-mounted versus
>wing-mounted guns?
No comment here.
Will Martin
From Will Martin <wma...@STL-06SIMA.ARMY.MIL>
I've been viewing various WWII film clips lately, due to the 50-year
anniversary and the appearance of programs on the subject on TV, and I've
been struck by an odd little aspect of air-combat footage.
It seems inevitable that film editors will splice together shots of
aircraft taken from gun cameras, interspersed with close-up film of
the muzzles of guns in fighter-plane wings firing. This what I am
curious about.
1) Am I right in assuming that all these shots of wing-guns firing had
been taken on the ground? That is, no one ever rigged up a camera in a
pod or mounted on a boom, aimed back at the wing leading edge, to
actually film the guns firing while in flight? I suppose doing this would
have been possible in flight testing phases, but it sure seems awkward.
Therefore, I am guessing that all such shots were filmed on the ground,
and then just spliced into air-combat footage for dramatic effect. Any
comments on this?
2) Some fighters have the gun muzzles recessed into the wing, behind the
leading edge. When these close-up firing pictures are shown, one can see
bits of fabric around the gun-muzzle-openings in the wings dancing about
as the gasses from firing rush by. Were these openings covered with
fabric that the guns fired through? Was this fabric renewed each flight?
Why? Did it help the aerodynamics of takeoff? Was such fabric-covering
dispensed with as the fighting grew more intense (that is, was it an
item of maintenance that could be dispensed with when time was pressing)?
Didn't this fabric ever catch fire, and present a hazard to the plane?
3) Some varieties of fighters have recessed guns, as mentioned above.
Others have the gun muzzles extending out from the wings quite a bit (a
foot or more, it appears). Why do one versus the other? Was one style
characteristically German while the other was characteristically Allied
(or British, or American)? Or was it something that was a
designer/manufacturer trait, rather than associated with a country?
What are the advantages/disadvantages of each approach?
4) What are the advantages/disadvantages of fuselage-mounted versus
wing-mounted guns? It would seem that wing mounts would make disposing
of fired-cartridge cases easier, and less likely to interfere with or
damage the aircraft, but that fuselage-mounting would allow greater
ammunition-carrying capacity. Is this correct? Any other points?
Regards, Will
wma...@stl-06sima.army.mil OR wma...@st-louis-emh2.army.mil
Gregory A. Hooten
From gaho...@orion.arc.nasa.gov (Gregory A. Hooten)
(2) Fabric over the gun port.
Many ground crews (I have read) would put "tape" over the gun
opennings of the flush mounted machine guns. Flush as in the
barrel was equel to or recessed in the wing entirely. This
allowed the ground crews to know if the fighters had been in a
scrap before the pilots got out of the planes, indeed, before
many landed, they could tell with binoculars that they had
seen action. I have heard no other explanation for this.
Wing mounted vs. fusalage mounting.
The wings on most American fighters were quite large and deep.
The P-51 and P-47 both carried large amounts of amunition and
a large number of guns in the wing. P-51 6 X 50 Cal. and P-47
8(!) X 50 Cal. I have read only a few stories about running
out of ammunition before the range of the fighter was met.
Mostly the defender ran out of ammo before their range was
exceeded. Many German fighters were downed by 1 - 2 second
bursts from the P-47, as the concentration of fire was
intense.
One disadvantage of wing mounted guns is that they had to be
set to meet at a certain range. As they were angled slightly
inward rather than parallel to each other. In the centerline
mounting as in the P-38 with 4 X 50 Cals, and 1 X 20MM cannon,
they were mounted parallel as the need to have them cross at
some fixed range was obviated by the placement.
Greg Hooten
gaho...@george.arc.nasa.gov
Paul Stacy
From jfr...@ada.stat.uga.edu (Paul Stacy)
In article <1991Sep24.2...@cbnews.cb.att.com> wma...@STL-06SIMA.ARMY.MIL (Will Martin) writes:
>2) Some fighters have the gun muzzles recessed into the wing, behind the
>leading edge. When these close-up firing pictures are shown, one can see
>bits of fabric around the gun-muzzle-openings in the wings dancing about
>
It was common to put tape over the openings of the gun opening to
improve air flow over the wing. Without it air can get "packed" into
the opening of the gun and reduce performance (though it doesn't seem
like
it would be enough to make much difference.
>3) Some varieties of fighters have recessed guns, as mentioned above.
>Others have the gun muzzles extending out from the wings quite a bit (a
>From my understanding from reading and seeing a lot, the ones that stick
out are cannons and the ones that are recessed are machine guns.
In the case of the P-38 with four machine guns and a cannon in the nose,
the cannon was the only one that didn't stick out though.
Paul "Joe Friday" Stacy (not net.police) Buffalo State College, New York
STA...@SNYBUFVA.BITNET (Buffalo State College VAX) JUST THE
jfr...@ada.stat.uga.edu (Univ. of Georgia, Athens UNIX) "VAX", MA'AM!
Disclaimer: This isn't the opinion of the school, police, Chief of Detective
Staff Brown, Planet Spaceball, Starfleet Command, or the Pentagon.
Gym Z. Quirk
From tkogoma%triton....@lynx.unm.edu (Gym Z. Quirk)
In article <1991Sep24.2...@cbnews.cb.att.com> wma...@STL-06SIMA.ARMY.MIL (Will Martin) writes:
>I've been viewing various WWII film clips lately, due to the 50-year
>anniversary and the appearance of programs on the subject on TV, and I've
>been struck by an odd little aspect of air-combat footage.
>[...]
>2) Some fighters have the gun muzzles recessed into the wing, behind the
>leading edge. When these close-up firing pictures are shown, one can see
>bits of fabric around the gun-muzzle-openings in the wings dancing about
>as the gasses from firing rush by. Were these openings covered with
>fabric that the guns fired through? Was this fabric renewed each flight?
>Why? Did it help the aerodynamics of takeoff? Was such fabric-covering
>dispensed with as the fighting grew more intense (that is, was it an
>item of maintenance that could be dispensed with when time was pressing)?
>Didn't this fabric ever catch fire, and present a hazard to the plane?
According to _Fighter_ and _The Battle of Britain_ by Len Deighton,
the fabric coverings on the Spitfires and Hurricanes were to prevent
ice from stopping the gun muzzles at high altitude. I would assume
that the coverings would be re-applied during aircraft turnaround.
Of course, I also recall some refrences to incindiary-tipped .30 cal
ammunition in use at the time. (As I understand, it made comfirming
hits much easier). I suppose the fabric wasn't hard enough to ignite
them, but it doesn't strike me as particularly safe.
>3) Some varieties of fighters have recessed guns, as mentioned above.
>Others have the gun muzzles extending out from the wings quite a bit (a
>foot or more, it appears). [...]
>What are the advantages/disadvantages of each approach?
The primary advantage to exposed muzzles that I can think of would be
the air-cooling the airstream allows the guns. I'm not sure if the
enclosed wing guns suffered from overheating problems, tho.
>4) What are the advantages/disadvantages of fuselage-mounted versus
>wing-mounted guns? It would seem that wing mounts would make disposing
>of fired-cartridge cases easier, and less likely to interfere with or
>damage the aircraft, but that fuselage-mounting would allow greater
>ammunition-carrying capacity. Is this correct? Any other points?
Wing stress. The fusalage could support a heavier recoil weapon.
(i.e. early war 20mm cannon). The wing mounts were usually restricted
to Machine guns.
(Of course, later in the war, the structural strength of the wings was
imporved to the point that multiple canon could be mounted.)
>Regards, Will
>wma...@stl-06sima.army.mil OR wma...@st-louis-emh2.army.mil
--
Capt. Gym Z. Quirk (Known to some as Taki Kogoma) tko...@triton.unm.edu
Veteran of the "Grand sf-lovers fiasco" of July '91-???.
Secret Master of rec.arts.startrek
-= Insert witty quote here =-
Ami A. Silberman
From sil...@m.cs.uiuc.edu (Ami A. Silberman)
wma...@STL-06SIMA.ARMY.MIL (Will Martin) writes:
I really don't know enough to answer the other questions, but this I
can.
>4) What are the advantages/disadvantages of fuselage-mounted versus
>wing-mounted guns? It would seem that wing mounts would make disposing
>of fired-cartridge cases easier, and less likely to interfere with or
>damage the aircraft, but that fuselage-mounting would allow greater
>ammunition-carrying capacity. Is this correct? Any other points?
The advantage of the wing-mounted guns was two-fold, a) you could put
more of them on (The Huricane and Spitfire, for instance, had 8 .303
machine guns), and you also didn't need interuptor gear to avoid hitting
the prop. Some designs actually had both wing and fuselage mounted
guns (especially German designs). Autocannons were primarily mounted
in the wing roots, they still had to use interupter gear, but were
placed there because of the recoil.
The advantage of fuselage-mounted guns is primarily in aiming. Since
the guns are all in the same place, they all fire as a stream. Note
that two-engine planes tended to mount some quite heavy armament there,
the P-38, Me-110, Me-262 and Mosquito are the main examples. When dealing
with wing mounted guns, the guns are slightly angled so as to concentrate the
fire at a certain distance. This was usually adjustable, but I think only
on the ground.
Now for my question: I've read that the Me-109C (Bf-109C) had an auto-cannon
in the prop-hub (in addition to the two in the wing roots, and the two MGs
above the engine). I've also read that it didn't, that the first ones did
and the latter ones (still in the E model) didn't, that the prototypes
did, and the production ones didn't, that they all did, but were removed due
to difficulties etc. (I'm pretty sure it was the C model, the one that
was used in 1940.) Anyone know anything for sure?
--
ami silberman - janitor of lunacy
sil...@cs.uiuc.edu
usenet!ames!newserv...@att.att.com
From usenet!ames!newserve.cc.b...@att.att.com
Wings v. Fuselage:
Besides syching the guns through the prop, or putting on two engines, there
was a third solution used in the Air Cobra and the King Cobra. Those airplanes
had their cannons fire through the hub.
|
|
|
|
\
------------------\__
Cannon--> |
__________________ __|
/
/
|
|
|
|
It had some teehing problems as I recall, but the Russians especailly liked
the weapon as a tank buster.
=================================================================
= =
= David Kane con...@bingsuns.cc.binghamton.edu =
= =
= "I'm here." =
= =
=================================================================
imj...@csc1.anu.edu.au
From imj...@csc1.anu.edu.au
In article <1991Sep26....@cbnews.cb.att.com>, sil...@m.cs.uiuc.edu (Ami A. Silberman) writes:
>
> Now for my question: I've read that the Me-109C (Bf-109C) had an auto-cannon
> in the prop-hub (in addition to the two in the wing roots, and the two MGs
> above the engine). I've also read that it didn't, that the first ones did
> and the latter ones (still in the E model) didn't, that the prototypes
> did, and the production ones didn't, that they all did, but were removed due
> to difficulties etc. (I'm pretty sure it was the C model, the one that
> was used in 1940.) Anyone know anything for sure?
The main variant of the bf 109 used in 1940 was the E-3 or E-4, having entered
service in late 1938. The F series entered service in spring 1941. Some Cs
were still on strength at the outbreak of war in 1939, and participated in the
Polish campaign. They were used for home defence until spring 1940, after
which they were used as trainers.
In "Combat Aircraft of World War Two" by Weal et. al., the following variants
are listed:
Bf 109B-1 2 x 7.9mm MG 17 in upper cowling
C-1 as above + 2 x 7.9mm MG 17 in wings
C-2 as C-1 + 1 x 7.9mm MG 17 engine mounted
C-4 as C-2 but with engine mounted MG replaced with 20mm MG FF
cannon (project only)
D-1 2 x 7.9mm MG 17 in upper cowling + 20mm MG FF in engine
V14 2 x 7.9mm MG 17 + 2 x 20mm MG FF cannon (prototype)
E-0 4 x 7.9mm MG 17 (preproduction model, 10 only)
E-1 2 x 7.9mm MG 17 in upper cowling + 2 x 20mm MG FF in wings
E-3 as E-1 + 1 x 20mm MG FF engine mounted BUT usually deleted in
service
E-4 as E-1, modified armament (?), nose cannon deleted
F-1 2 x 7.9mm MG 17 in cowling + 1 x 20mm MG FF/M in engine
F-2 as F-1 but 20mm MG FF/M replaced with 15mm MG 151 cannon
F-4 as F-1/F-2 but 15 mm MG 151 replaced with 20mm MG 151 cannon
G-1 as F-4
G-5 as F-4 but 13mm MG 131 machinge guns replaced the 7.9mm MG 17s
G-10 1 x 30mm MK 108 (or 20mm MG 151) engine mounted + 2 x 13mm
MG 131 in upper cowling
K-0 three cannon armament
K-2,4 late models with 30mm MK 103 cannon
K-6 20mm MG 151 cannon in upper cowling replaced with 2 x 13mm
MG 131 machine-guns
K-14 2 x 13mm MG 131 in upper cowling + 1 x 30mm MK 108 in engine
716-253-7825
From Rick Lafford (716-253-7825) <laf...@serum.Kodak.COM>
The crankshaft mounted cannon used in some of the Bf109E's did
not work well due to a very slow firing rate and it's tendency to jam.
The Germans tended towards cannon due to the mission requirements of
shooting down large slow moving bombers. The problems with cannon are
the greater weight of the cannon and ammunition and their comparitively
slow rate of fire. This is not a problem if you are attacking a slow
unmaneuverable target but is a significant problem if you must deal
with fighters. Note that the Germans usually tried to have fighters
fly cover for the fighters attaching our bombers. This was partially
due to the latters lower maneuverability with the 30mm cannon pods or
rockets carried underwing.
The US has always gone for throw-weight in fighter aircraft armament.
It is very hard for a fighter to fly through the fire of 6-8 50cal.
Brownings. Since the time a fighter is likely to be within your firing
envelope is short, placing the maximum number of projectiles in his
path seems to be a good idea.
-Rick
Rick Lafford
Clinical Products Division
Eastman Kodak Co.
Rochester, NY. 14619
Al Crawford
From Al Crawford <aw...@dcs.ed.ac.uk>
In article <1991Sep26....@cbnews.cb.att.com> sil...@m.cs.uiuc.edu (Ami A. Silberman) writes:
>
>The advantage of fuselage-mounted guns is primarily in aiming. Since
>the guns are all in the same place, they all fire as a stream. Note
>that two-engine planes tended to mount some quite heavy armament there,
>the P-38, Me-110, Me-262 and Mosquito are the main examples. When dealing
>with wing mounted guns, the guns are slightly angled so as to concentrate the
>fire at a certain distance.
A couple of related points - were fuselage-mounted guns ever angled to
concentrate their fire? I'd imagine that just firing straight ahead would
be enough to do the job (streams of fire roughly a couple of feet to a
metre apart) but would there be any advantage in setting fuselage-mounted
weapons to converge at a particular range also (thereby *really*
concentrating fire at the right range)?
Following on from this, given the advantages of fuselage-mounted weapons,
it strikes me as rather surprising that fewer pusher planes appeared during
WWII - fuselage-mounted weapons seem to require either two engines (giving
a clear field of fire but with a size and weight penalty) or interruptor
mechanisms whereas a pusher configuration gives the same excellent field of
fire as two engines but without the weight problem. It also *seems* to give
a rather clean airframe. The only WWII pusher design to see service that I
can think of was the Saab J-21 (was it the J-21? It was reborn post-war
with a jet engine as the J-21R, yes?) which mounted all its weaponry (4
MGs?) in the nose. Oh, and there was some German beastie (Dornier 335 I
think) but that cheated by having a push-pull arrangement and a Japanese
pusher with a 6-bladed prop but I don't think that ever saw service. What
were the problems with the pusher configuration that made it unpopular?
--
Al Crawford - aw...@dcs.ed.ac.uk
"Such a digital lifetime, it's been by numbers all the while"
Dave Pierson
From pie...@cimcad.enet.dec.com (Dave Pierson)
In article <1991Sep26.0...@cbnews.cb.att.com>,
George.P...@att.att.com (George Patterson) writes, in part:
>Let me add a question to the list. We've all seen the "gun camera" films
>of a plane being hit and going down in flames - all the way down.
Somewhere reasonably authoritative i saw it written that, in US
practice the trigger, (switch, actually) had two positions. Pull all
the way, guns and camera. Release to intermediate, camera only.
Interesting "spur of the moment" recce could be done by a partial pull.
(yeah, the itty bitty frames from the 16mm gun cameras didnt give
Super quality, but better than nothing.)
thanks
dave pierson |the facts, as accurately as i can manage,
Digital Equipment Corporation |the opinions, my own.
pie...@cimnet.enet.dec.com
Christopher Biow
From bi...@cs.umd.edu (Christopher Biow)
In article <1991Sep27....@cbnews.cb.att.com> laf...@serum.Kodak.COM (716-253-7825) writes:
>The crankshaft mounted cannon used in some of the Bf109E's did
>not work well due to a very slow firing rate and it's tendency to jam.
It's no wonder it jammed, having to fire through all those 90 degree
bends in the crankshaft! :-)
Maybe you mean _driveshaft_?
DENVER CHUAN-HIN TAM
From dc...@eos.ncsu.edu (DENVER CHUAN-HIN TAM)
>A couple of related points - were fuselage-mounted guns ever angled to
>oncentrate their fire? I'd imagine that just firing straight ahead would
>be enough to do the job (streams of fire roughly a couple of feet to a
>metre apart) but would there be any advantage in setting fuselage-mounted
>weapons to converge at a particular range also (thereby *really*
>concentrating fire at the right range)?
Sure. I've read many instances where the guns were harmonised to
converge at about 150 yds or so. Imagine 8 x .303 brownings all
at one point. I think that it was a common practice among the better
British pilots. The general method (or so I've read) was not to fully
converge the guns at some point, because most (not all) pilot were
not really good shots who could take adventage of full convergence.
So, they arrange a fairly large spread pattern thereby maximizing the
chance of a hit while taking away the full punch. This is totally
from what I've read and may be wrong. Check out Douglas Bader's
Biography 'Reach for the sky' and I think it explains this pretty
well there.
Jesse William Leo Stuart
From jwst...@ecst.csuchico.edu (Jesse William Leo Stuart)
In article <1991Sep24.2...@cbnews.cb.att.com> wma...@STL-06SIMA.ARMY.MIL (Will Martin) writes:
>
>
>From Will Martin <wma...@STL-06SIMA.ARMY.MIL>
>I've been viewing various WWII film clips lately, due to the 50-year
>anniversary and the appearance of programs on the subject on TV, and I've
>been struck by an odd little aspect of air-combat footage.
>
>It seems inevitable that film editors will splice together shots of
>aircraft taken from gun cameras, interspersed with close-up film of
>the muzzles of guns in fighter-plane wings firing. This what I am
>curious about.
>
>1) Am I right in assuming that all these shots of wing-guns firing had
>been taken on the ground? That is, no one ever rigged up a camera in a
Any camera mounting that would allow the angle to shoot the guns
would have seriously unballanced the airplane in flight, so all those pictures
were taken on the ground. I don't know how many were shot during gun
calibration exercises (ie, the guns are fired with the airplane in a fixed
possition parellel to the ground, the guns were aimed at a pre-specified point).
These exercises allowed a perfect time to film guns firing.
>2) Some fighters have the gun muzzles recessed into the wing, behind the
>leading edge. When these close-up firing pictures are shown, one can see
>bits of fabric around the gun-muzzle-openings in the wings dancing about
>as the gasses from firing rush by. Were these openings covered with
Many pilots covered their guns with duct tape to make an
more aerodynamic airflow over the gun ports. This could add to the fuel radius
of the plane.
>3) Some varieties of fighters have recessed guns, as mentioned above.
>Others have the gun muzzles extending out from the wings quite a bit (a
>foot or more, it appears). Why do one versus the other? Was one style
The most important aspect of aircraft design is space allocation,
ie how to situate the various internal airplane components to most efficiently
use the space provided by the airframe. If a plane needed greater fuel storage,
moving the guns forward might provide a few more cubic feet of feul space.
A good example of this is a reconisance version of the Spitfire which had no
guns at all, but had a very large combat radius ( >1,000 mi), while the armed
Spitifre it was developed from had a small combat radius ( <500 mi)!
>4) What are the advantages/disadvantages of fuselage-mounted versus
>wing-mounted guns? It would seem that wing mounts would make disposing
The largest advantage of a fuselage mounted gun is stability, and
space available for amunition. However, when a fuselage mounted gun has to
fire forward, the mount for that gun has to protrude into the airstream,
thus adding to the plane's drag. If you put the guns in the wings, they
will be less stable, but you can point them forward without adding to drag,
since the wings are rather necessary anyway (8-}). Another advantage of
fuselage mounted guns is that it is much easier to aim them, since you just
point the plane in the direction you wish to fire, while wing mounted guns m
must be calibrated to shoot at a specific distance in front of the plane.
One of the best gun mounts of WW2 was the P-38 Lightning. All of it's guns
were mounted on the central nacell infront of the cockpit.
Jess Stuart
@CSUC Chico, CA
716-253-7825
In reference to Dave Pierson's comments on 16mm gun cameras:
Actually, when isolated from vibration and using a good fast color
film the cameras produce very good pictures. I've seen some
spectacular footage shot from the tail of a glider with a converted
16mm gun camera. The mechanism is fine and the original lenses were
pretty good. This camera had the lense replaced with a more modern
color corrected lens. The only drawback is the limited magazine
capacity. Otherwise, the light weight of the camera is very usefull.
BTY--The film maker who I know used the camera is Chris Woods and the
films were "The Silent Challenge" and "Running on Empty" both glider
pics.
--Rick
Eastman Kodak Co.
Rochester, NY 14619
"The fact that I work here as a consultant doesn't mean that they ever
actually ask for my opinion."
--6 figure Teamwork consultant at EK
716-253-7825
In response to Al Crawfords question on pusher configurations:
Fuselage mounted guns were often set to converge at the maximum
effective range of the guns thus concentrating firepower at long
ranges and holding the pattern as tight as possible.
Pusher configurations have some significant problems as well as many
advantages. One great problem has always been cooling. Yes, you can
put a radiator pod on the belly for a liquid cooled engine but the
turbulence induced by the pod reduces the effective thrust of the
prop. Air cooled engines have airflow problems when mounted in the
rear. The second issue arises when you rotate for takeoff or landing
and the prop rotates downward into the ground. Unless you build long
gear legs, the prop is too close to the ground to allow for much
rotation on takeoff or landing. This makes for fairly 'hot' land
speeds when compared to the typical taildragger configuration of
WWII fighters.
BTW--How would you like to crash land an aircraft with a V12 tucked
away behind your posterior? Could get a little tight in the front
cockpit, yeah.
--Rick
Eastman Kodak Co
Rochester, NY
You know, George's place by the lake.
military@cbnews
From att!bcr!mruxb!patter
The pusher propeller is less efficient than a tractor type because it's
located in the turbulence of the fuselage, wings, and control surfaces.
Stefan
From sm...@venus.lerc.nasa.gov (Stefan)
>wma...@STL-06SIMA.ARMY.MIL (Will Martin) writes:
>>4) What are the advantages/disadvantages of fuselage-mounted versus
>>wing-mounted guns? It would seem that wing mounts would make disposing
One disadvantage of wing-mounted guns is the possible jams caused by
high centrifugal forces during manoeuvres.
____________________________
May all your scores be 'X's!
_____________________________
716-253-7825
In reference to Christopher Biow's reply:
>Maybe you mean _driveshaft_?
Thanks Christopher. I must be working on too many projects at once and
it's causing some terminal brainfade.
BTW- Does anyone know what kind of geardrive was used on the Bf109. I'm
interested in gear types, wet/dry, ratios etc. We seem to have a problem
building reliable gearboxes today, so I'm curious as to how the the Germans did
it in pre-WWII.
-Rick
Clinical Products Division
pric...@devon.larc.nasa.gov
From pric...@devon.larc.nasa.gov
The pusher propeller is less efficient than a tractor type because it's
located in the turbulence of the fuselage, wings, and control surfaces.
not true that pushers are less efficient. they do intake more turbulent
air, but their output doesn't have any blockage. also, that nice pressure
gradient they create is just right for preventing flow separation on the
after surfaces of the fuselage (as opposed to a tractor creating them
where it is not beneficial).
the real problems with pushers are; FOD damage to the prop during ground
operations, difficulty with weight&balance due to aft engine location.
read the literature from the EAA (Experimental Aircraft Association) including
their monthly, "Sport Aviation" for more discussion of tractor vs. pusher.
--
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Devon Prichard "The atrocious crime of being a young |
| Lackey-in-Training man... I shall neither attempt |
| Lockheed Engineering & Sciences Co. to palliate nor deny." |
| pric...@devon.larc.nasa.gov William Pitt, House of Commons, 1741 |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Phil Stracchino
From ala...@sti.com (Phil Stracchino)
|> From sm...@venus.lerc.nasa.gov (Stefan)
|>
|> One disadvantage of wing-mounted guns is the possible jams caused by
|> high centrifugal forces during manoeuvres.
Sorry, this just isn't so. There's basically three situations in which
G-force on wing-mounted guns is going to be significantly different from
fuselage-mounted guns: flat turns, spins (especially flat spins), and
tight rolls. As to the first, fighter pilots just don't make high-G flat
turns, for several reasons. One is if you do, G-force throws you sideways
in the cockpit, which doesn't do wonders for maintaining proper control.
Another is that in a flat turn, the only surface acting to change your
direction is the (relatively small) rudder. The correct technique is to
roll so that the aircraft you're pursuing is "above" you, then pitch the
nose up to follow; you have far more aerodynamic surface acting to change
your direction, and the G-force is straight down into your seat, a lot
easier to take that sideforce.
When you're maneouvring in this way, 'centrifugal' force on wing guns
is basically little or no higher than on fuselage-mounted guns. In fact,
due to the lower turn rate you can attain in a flat turn, I suspect G
force on the guns is lower in a flat turn than it is in a hard banked turn.
Either way, I dount that it would amount to enough to jam the gun.
In Spins: I can imagine that you might have G-related jam problems in a
flat spin (though if you're in a flat spin, trying to shoot is probably
not one of your higher priorities).
In Rolls: Very simply, if you're following enother aircraft through a
roll tight enough to cause G-related feed problems or even jams, then
you probably can't get a firing solution on your target anyway. You may
be able to get your sights on him, but once your shells leave the muzzle
they continue in (for our purpose) a straight line; they don't follow
through the roll. You'd just be hosing cannon shells into empty air.
HOWEVER: Although jams caused by maneouvring G-force are unlikely to be a
major concern, it is true that wing-mounted cannon (heavy objects well off
the aircraft's centerline) will increase the aircraft's moment of inertia,
and therefore reduce the initial roll rate. Your sustained roll rate will
remain the same, but all other thinsg being equal, an aircraft with wing
mounted guns will go into and come out of a roll slightly slower than an
otherwise-identical aircraft with fuselage-mounted guns.
--
"Station Planet Earth is closing down: Transmission ends..." - Chris de Burgh
..............................................................................
The Renaissance Man: Phil V. Stracchino - ph...@sti.com - ala...@sti.com
==> Free Cyberia! Committee for a Free and Independent Cyberspace <==
Dave Pierson
From pie...@cimcad.enet.dec.com (Dave Pierson)
In article <1991Oct1.0...@cbnews.cb.att.com>,
pric...@devon.larc.nasa.gov writes, in part:
>From pric...@devon.larc.nasa.gov
>
>> The pusher propeller is less efficient than a tractor type because it's
>> located in the turbulence of the fuselage, wings, and control surfaces.
>
>not true that pushers are less efficient.
...
>read the literature from the EAA (Experimental Aircraft Association) including
>their monthly, "Sport Aviation" for more discussion of tractor vs. pusher.
To which i would add, yea, verily. Consider two Bert Rutan designs:
the EZE and the ???? (round the world machine, bit rot sets in). Both
pushers. (okay, the second was a hybrid, which engine did they use
most?) Round the world on one tank of gas is pretty "efficient".
The EZE is outstandng for low gallons/hr. I suppose something odd
could happen at higher speeds, but an EZE isnt slow, either...
thanks
dave pierson |the facts, as accurately as i can manage,
Digital Equipment Corporation |the opinions, my own.
600 Nickerson Rd
Marlboro, Mass
01752 pie...@cimnet.enet.dec.com
"He has read everything, and, to his credit, written nothing." A J Raffles
Phil Stracchino
From ala...@sti.com (Phil Stracchino)
|> From pie...@cimcad.enet.dec.com (Dave Pierson)
|>
|> To which i would add, yea, verily. Consider two Bert Rutan designs:
|> the EZE and the ???? (round the world machine, bit rot sets in). Both
|> pushers. (okay, the second was a hybrid, which engine did they use
|> most?) Round the world on one tank of gas is pretty "efficient".
You're thinking of the Voyager, I believe. I seem to recall they spent
most of the time running on the forward engine, since the aft engine was
overheating - the limited airflow the design allowed to the aft engine
caused cooling problems.
Interestingly, this was a problem that they thought might abort the attempt,
because (if memory serves) the plan was to run on the aft engine most of the
time, since it produced less induced drag and was therefore more efficient
than the forward engine. (I think it may have been a smaller engine, too,
but I don't recall for sure.)
Stefan
From sm...@venus.lerc.nasa.gov (Stefan)
ala...@sti.com (Phil Stracchino) writes...
>|> From sm...@venus.lerc.nasa.gov (Stefan)
>|>
>|> One disadvantage of wing-mounted guns is the possible jams caused by
>|> high centrifugal forces during manoeuvres.
>
>Sorry, this just isn't so. There's basically three situations in which
>G-force on wing-mounted guns is going to be significantly different from
>fuselage-mounted guns: flat turns, spins (especially flat spins), and
>tight rolls.
In a turn that does not lose altitude, the outboard wing will be further
away from the center of the turn and therefore is under higher centrifugal
force than the inboard wing or fuselage.
Galland in his book mentions jams caused by turns, and this centrifugal induced
jam is one of the reasons why some pilots do not fire their guns in tight turns.
>As to the first, fighter pilots just don't make high-G flat
>turns, for several reasons. One is if you do, G-force throws you sideways
>in the cockpit, which doesn't do wonders for maintaining proper control.
>Another is that in a flat turn, the only surface acting to change your
>direction is the (relatively small) rudder.
The Fokker DR I can and did flat turns often. It was one of the reasons
that many of the German aces preferred the DR I. Von Voss outmanoeuvred
about seven allied aces for half an hour with this technique until he
was overcome.
>The correct technique is to
>roll so that the aircraft you're pursuing is "above" you, then pitch the
>nose up to follow; you have far more aerodynamic surface acting to change
>your direction, and the G-force is straight down into your seat, a lot
>easier to take that sideforce.
The G force is towards the center of the turn (in a steady turn) and, relative
to the aircraft, is down and towards the outside. The G force will be through
your seat only in a vertical bank.
..
>In Rolls: Very simply, if you're following enother aircraft through a
>roll tight enough to cause G-related feed problems or even jams, then
>you probably can't get a firing solution on your target anyway.
That depends on the flying skill and marksmanship of the pursuing pilot.
I've read of accounts of pilots getting some of their kills in such a
manoeuvre.
mruxb!...@bcr.cc.bellcore.com
From mruxb!pat...@bcr.cc.bellcore.com
Phil Stracchino writes -
>|> From sm...@venus.lerc.nasa.gov (Stefan)
>|>
>|> One disadvantage of wing-mounted guns is the possible jams caused by
>|> high centrifugal forces during manoeuvres.
>
>Sorry, this just isn't so. There's basically three situations in which
Sorry, but this *is* so. Maybe it's not true in theory, but in practice
quite a number of combinations of guns and aircraft were found to be
incompatible during WWII.
The first case that comes to mind is the early attempts to mount
cannon in the wings of a Hurricane. The gun had performed quite well
when fuselage mounted in other aircraft, but jammmed in the Hurricane.
In this particular case, centrifugal force was pinning the shells in the
feed chutes with the wing mounting. This did not occur with a fuselage
mount.
Keep in mind that at least one of the wings will be subjected to higher
"G" forces when entering turns than the fuselage. In addition, no pilot
is going to pay a whole lot of attention to keeping his turns coordinated
in a dogfight, and this wrecks any attempt to view the topic logically.
pric...@devon.larc.nasa.gov
From pric...@devon.larc.nasa.gov
pie...@cimcad.enet.dec.com (Dave Pierson) writes:
To which i would add, yea, verily. Consider two Bert Rutan designs:
the EZE and the ???? (round the world machine, bit rot sets in). Both
pushers. (okay, the second was a hybrid, which engine did they use
most?) Round the world on one tank of gas is pretty "efficient".
The EZE is outstandng for low gallons/hr. I suppose something odd
could happen at higher speeds, but an EZE isnt slow, either...
here again, it is difficult to directly compare actual aircraft. the Rutan
designs, as well as most homebuilts, have less wing area. this gives higher
stall and landing speeds (which is why Cessna hasn't gone that route), but
gives less cruise drag.
but the bottom line is still that, using careful propeller aerodynamic
calculations, various people have found pushers to be more efficient. when
viewed in terms of total marketablility, though, the tractor still has
many fans (ouch).
David Fricker
From fsf...@bones.lerc.nasa.gov (David Fricker)
In article <1991Oct1.2...@cbnews.cb.att.com> pie...@cimcad.enet.dec.com (Dave Pierson) writes:
>From pie...@cimcad.enet.dec.com (Dave Pierson)
>In article <1991Oct1.0...@cbnews.cb.att.com>,
>pric...@devon.larc.nasa.gov writes, in part:
>>From pric...@devon.larc.nasa.gov
>>> The pusher propeller is less efficient than a tractor type because it's
>>> located in the turbulence of the fuselage, wings, and control surfaces.
>>not true that pushers are less efficient.
>...
>>read the literature from the EAA (Experimental Aircraft Association) including
>>their monthly, "Sport Aviation" for more discussion of tractor vs. pusher.
>
> To which i would add, yea, verily. Consider two Bert Rutan designs:
> the EZE and the ???? (round the world machine, bit rot sets in). Both
>>> Voyager <<<
> pushers. (okay, the second was a hybrid, which engine did they use
> most?) Round the world on one tank of gas is pretty "efficient".
^^^^
Sorry, I forget also. My faulty memory says that both engines
were used for climb, but only one was used for cruise.
Rutan has designed a fair number of planes (Quickie, Long E-Z,
Beech Starship, etc.) with pusher props. The Beech Starship is
operates in pretty much the same speed range as WWII fighters.
Basically, pusher vs. tractor props result from conventions/mindsets.
But even Rutan designs tractor prop aircraft.
--
--------------------------------------------------------------------------
David Fricker voice: 216-433-5960
NASA Lewis Research Center email: fsf...@bones.lerc.nasa.gov
--------------------------------------------------------------------------
"Of the seven dwarves, only Dopey had a shaven face. This should tell us
something about the custom of shaving." -- Tom Robbins, <Skinny Legs and All>
Charles K. Scott
From Charles...@dartmouth.edu (Charles K. Scott)
In article <1991Sep30.0...@cbnews.cb.att.com>
jwst...@ecst.csuchico.edu (Jesse William Leo Stuart) writes:
> However, when a fuselage mounted gun has to
> fire forward, the mount for that gun has to protrude into the airstream,
> thus adding to the plane's drag. If you put the guns in the wings, they
> will be less stable, but you can point them forward without adding to drag
Jess I'm not sure where you read this, but machine guns were originally
mounted to the fuselage in WW1 because it was a nice solid part of the
aircraft to bolt them and it allowed the pilot to sight down the guns.
Very few fuselage mounted guns, be they machine gun or cannon protruded
out of the fuselage barring the P-38 and other twins. Most of the
single engined fighters that mounted machine guns on the fuselage had
them flush mounted. I don't believe aerodynamics was the consideration
in this case.
On a different point, the Messerschmidt BF-109E did not mount a cannon
in its nose to fire through the prop hub at least not at the time of
the Battle of Britain. Many drawn or painted illustrations show E
models blasting away with flame blossoming from the little hole in the
prop spinner, but no actual photographs. "Fighter" by Len Deighton is
pretty definative about this point. Later, when the cannon was mounted
between the cylinder banks on later models, it actually fired through
the hollow prop hub, not the crankshaft or driveshaft, although I guess
you could consider the prop drive to be a driveshaft:-) Len also speak
about the armament of the 109 saying that because of the many
modifications to the 20mm cannon mounted on the wings to make it light
enough to be carried on the aircraft, it had a very low muzzle velocity
making aiming difficult. The pilot had to get very close and often
used the machine guns as an aiming device, ie get them hitting then
trigger the cannon.
Corky Scott
Charles K. Scott
From Charles...@dartmouth.edu (Charles K. Scott)
In article <1991Oct1.2...@cbnews.cb.att.com>
ala...@sti.com (Phil Stracchino) writes:
> Although jams caused by maneouvring G-force are unlikely to be a
> major concern
Actually Phil there were several aircraft that had jamming problems due
specifically to the G forces the pilots were putting their aircraft
through. The P-51B Mustang and the early Wildcats both encountered G
force related jams. In the Wildcat it turned out to be a problem with
the ammo chute that fed the breeches, it was made from aluminum and
deformed under heavy load stopping the belt. A similar problem existed
in the early 51's, the B models. They two experienced firing stoppages
due to beltpath chutes that deformed during heavy G manuvers. All this
was fixed with the D model which added two more 50cal machine guns
making 6 for the D.
In answer to another question about the harmonization range or "sweet
spot" where the paths of the machine guns converged on the Spitfires
and Hurricanes, originally the Air Ministry specified that the guns be
set to harmonize at 450 yards or so because (as was stated in one of
the postings), not all the pilots were actually very good shots. It was
thought, by people who weren't going to do the fighting, that the
chance of hitting something would be increased with this arrangement.
While this may have been true, most pilots realised right away that
this penalized everyone because the .303 cal bullets were not of
sufficient size to do much damage so lots of them needed to be used.
By the end of the Battle of Britain, most pilots had had their machine
guns adjusted to harmonize at 150 yds.
Corky Scott
716-253-7825
Re: Misc. comments on centrifugal force causing gun jams.
A flat turn is not a viable maneuver in modern ACM. Yawing to point
your gun(s) at some point is valid but temporary and has some
undesirable side effects (see a later posting on the Magnus Effect).
Flat turns do not allow you to pull the nose thru the maximum number
of degrees per unit time and is very inefficient. You can also end
up in an inverted entry to a spin very quickly doing this and some
modern aircraft do not recover from this type of maneuver.
I don't intend to argue that wing mounted guns jam more or less than
fuselage mounts or that higher G forces don't complicate the problem but
a few things need to be understood.
Fuselage mounted guns often have a warmer environment to operate in and
hence have less icing problems. They also have shorter horizontal runs
on the feed chutes which lowers the friction forces when the aircraft
maneuvers. Many aircraft had jam problems due to icing of the gun
breech and feed tray design problems.
>Keep in ming that at least one of the wings will be subjected to higher
"G" forces...
Not true. Remember that the aircraft doesn't pivot around a point attached to
the inside wingtip. The outer wing does have a greater radius of turn but
the actual pivot of a cordinated turn is located by drawing a line vertically
thru the seat.
>The G force will be through your seat only in a vertical bank.
I don't know about that. In all my instruction and through personal experience,
I have found that in coordinated flight, the G forces will always be through
your seat though they may vary from plus to minus. Drastically uncoordinated
flight (skidding turns) are very inefficient and bleed energy rapidly. Energy
is one of those things fighter pilots rarely have enough of (I won't
mention the others ;-)) and was the last thing you wanted to waste in a WWII
vintage fighter.
>In Rolls:
Straight aileron rolls are not a high G maneuver. Any other roll is more
of a rolling turn and can have any amount of G force associated with it,
both negative and positive. Trying to bring guns to bear an apponent
during a rolling turn is mostly luck past having the skills needed to
stay in the rolling turn in the first place. The more common technique
used to get your nose to point where you think you opponent is going
to be several seconds hence is to roll to the required attitude then
pull the nose to the point. Then you hope the guy continues his roll
and flies thru the point you chose until, "Jesters Dead!"
-----------------------------------------------------------------------------
Rick Lafford
>From Georges place by the lake.
-----------------------------------------------------------------------------
mruxb!...@bellcore.bellcore.com
From mruxb!pat...@bellcore.bellcore.com
In article <1991Oct1.0...@cbnews.cb.att.com>,
pric...@devon.larc.nasa.gov writes, in part:
>From pric...@devon.larc.nasa.gov
>
>> The pusher propeller is less efficient than a tractor type because it's
>> located in the turbulence of the fuselage, wings, and control surfaces.
>
>not true that pushers are less efficient.
...
>read the literature from the EAA (Experimental Aircraft Association) including
>their monthly, "Sport Aviation" for more discussion of tractor vs. pusher.
Ok - what I *should* have said was that in WWII (the period in question)
aircraft manufacturers (at least the American ones) *believed* that the
pusher was less effective.
The original question ran along the lines of "why wasn't the pusher prop
used more in WWII aircraft design?". This belief (whether it's true or not)
*was* one of the factors.
The Discovery channel recently ran a Wings episode on the B-36 in which
they mentioned this fact. One of the first things the designers had to
do was convince their peers that the pusher design was acceptable. I have
run into mention of this in other places. One book, which I do not own,
claimed that this was established as "fact" in WWI. With a WWI aircraft,
it probably is true, since the WWI "pusher" was really a mid-engined
aircraft and had anything but a clean airflow behind the prop.
David L. Markowitz
From gtc.com!d...@elroy.Jpl.Nasa.Gov (David L. Markowitz)
pie...@cimcad.enet.dec.com (Dave Pierson) writes:
> To which i would add, yea, verily. Consider two Bert Rutan designs:
> the EZE and the ???? (round the world machine, bit rot sets in). Both
> pushers. (okay, the second was a hybrid, which engine did they use
> most?) Round the world on one tank of gas is pretty "efficient".
You refer, of course, to the Voyager. It was a push-pull, but used
its tractor for takeoff only.
My step-father was head of communications for the Voyager team, so you
might say I got a bit of insider info...
> The EZE is outstandng for low gallons/hr. I suppose something odd
> could happen at higher speeds, but an EZE isnt slow, either...
Rutan also designed the Long EZE, and the COZY (a two seater).
I believe they are pushers, too.
--
David L. Markowitz
Solaris Systems Division - Genisco Technology Corporation
d...@gtc.com
Bevin
From br...@tle.enet.dec.com (Bevin)
There has been a "yes-it-can" "no-it-can't" discussion of jamming guns in
wings v. jamming guns in bodies.
I'm not an expert, but there are two severe differences between guns in wings
and in bodies.
(a) as an aircraft, especially a WWII aircraft, begins a roll, the acceleration
rates on the wings can be quite high. A Spitfire had a peak roll-rate at 200
mph of 150 degrees per second. This rate was attained within one or two
seconds of the roll being initiated - basically in the time it took the pilot
to force the stick over to the side. Consider the two types of acceleration
this imposes on a gun about 2 metres from the central axis.
up/down - in about 2 seconds the wing goes from 0 m/s around the circle
to 2.pi.r/2 m/s = 6 m/s. This takes about 3 m/s/s or 1/3g. 2/3g if the
pilot is strong and in a hurry :-) Of course, for the wing that goes up
this is in the opposite direction to the wing that goes down
centrifical force when the wing has reached full roll rate is,
a = r(w**2) about 2*(2.5**2) m/s/s = about 1g
I guess I'd be a little surprised, but not badly so, if this is enough to
cause the guns to jam. In a tight turn it would be not unreasonable for the
guns to be firing under a 5g load, which is substantially more, but not a lot
more, than these.
(b) a more serious concern [and I think I read this really happened in the
Spitfire] is that the guns in the fusilage aren't mounted oriented the same
way as ones in the wing [necessarily]. I think that in the Spitfire the
thinness of the wing caused them to have to lay the .303 mg's on their side.
This may become a serious issue when you are trying to have the guns fire
reliably under a 5g load caused by turning, because this is 5g's in a direction
90degrees different from what they would experience mounted a different way.
/Bevin
s...@ollie.seas.ucla.edu
From s...@ollie.SEAS.UCLA.EDU
>From mruxb!pat...@bcr.cc.bellcore.com
>[...]
>is going to pay a whole lot of attention to keeping his turns coordinated
>in a dogfight, and this wrecks any attempt to view the topic logically.
Humphfffffff! the Baron is probably spinning like a top. Think about it for a
munite, in an uncoordinated turn you have (in addition to the Velocity vector
of the target) a veloicity vector that is NOT pointing where (or necessarily
even near) whre the guns & sight are pointing. In addition your rather simple
minded (but still helpful) computing gunsight is going to be even more confused.
-----
Stephen C. Woods; UCLA SEASNET; 2567 BH;LA CA 90024; (213)-825-8614
UUCP: ...{ibmsupt,ncar!cepu}!ollie}!scw Internet:s...@SEAS.UCLA.EDU
mruxb!...@bellcore.bellcore.com
From mruxb!pat...@bellcore.bellcore.com
Steven Woods has argued that pilots win't use uncoordinated turns in a
dogfight. An uncoordinated turn is also called a "slip" or "skid". An
aircraft in a slip is usually traveling sideways in a fairly straight
line; one in a skid is turning while traveling sideways. Either maneuver
is typically used by pilots to bleed off airspeed, since the plane is
actually traveling sideways. In combat, skids are used for the same thing,
if your fighter is overtaking another and you don't want to overshoot.
The maneuver is (or at least was) sometimes also used to bring the guns
to bear in a direction in which you don't happen to be flying (at the
expense of some airspeed). Most taildraggers can be pointed up to 45
degrees off course using the rudder.
As for "the baron spinning in his grave", another poster has already
reported the fact that "flat turns" (skids) were a primary tool in the
repetoire of a Fokker Dr1 pilot. Richtofen flew one of these quite well.
In any case, my original point was (and still is) that a pilot in a
dogfight does *whatever* seems to be required at the moment to bring his
guns to bear or to prevent his opponents' guns from staying on target.
While his training will result in most maneuvers being coordinated, many
will *not* be. If the British experiences in WWII are any indication,
the pilot will even occasionally lose control of the aircraft. If you
read accounts by Forrester or Johnson you'll run into phrases like
"skidding in behind him" or "barrelling out of the turn".
-----------------------------------------------------------------------
| The reason that cliches become cliches is that
George Patterson - | they are the hammers and screwdrivers in the
| toolbox of communication.
| Terry Pratchett
-----------------------------------------------------------------------
Henry Spencer
From he...@zoo.toronto.edu (Henry Spencer)
>From mruxb!pat...@bellcore.bellcore.com
>In any case, my original point was (and still is) that a pilot in a
>dogfight does *whatever* seems to be required at the moment to bring his
>guns to bear or to prevent his opponents' guns from staying on target.
>While his training will result in most maneuvers being coordinated, many
>will *not* be...
Also of note here is that uncoordinated maneuvers have a special advantage:
the very fact that the aircraft is pointing in one direction and flying in
another (to a degree) makes it harder for the opponent to predict its future
trajectory. Confusing the opposition can be worth a lot of lost airspeed.
(A more technological method of confusion is camouflage that makes it hard
to tell one side of the aircraft from the other. If you look at a good
photo of a Canadian F-18, for example, you'll see a fake cockpit canopy,
complete with pilot's helmet, painted on the underside. There are some
other bits of paint elsewhere on the underside to enhance this. Apparently
this works pretty well. The USAF and USN have declined to adopt it.
The official reason is that the added confusion in combat is not worth
adding dark areas of paint that make the aircraft easier to spot in the
first place. Maybe. Some people think that the *real* reason is that
the idea is patented -- by its inventor, aviation artist Keith Ferris --
and the thought of actually having to pay royalties to an "amateur" is
too much for the US military.)
--
In operating-system code, log(quality) | Henry Spencer @ U of Toronto Zoology
times quantity is a constant. | he...@zoo.toronto.edu utzoo!henry
Charles K. Scott
From Charles...@dartmouth.edu (Charles K. Scott)
In article <1991Oct4.0...@cbnews.cb.att.com>
laf...@serum.Kodak.COM (716-253-7825) writes:
> A flat turn is not a viable maneuver in modern ACM. Yawing to point
> your gun(s) at some point is valid but temporary and has some
> undesirable side effects (see a later posting on the Magnus Effect).
This may be true now, but during WWII, pilots often used the rudder to
hold their guns on an opponent long enough to do damage. Several
months ago I posted a question about the ability of the P-47 to manuver
with and shoot down FW-190's on the network. I cited the book
"Thunderbolt" by Robert L. Johnson who wrote about stamping on the
rudder and skidding his monstrous aircraft to draw a bead on a fleeting
enemy aircraft. I got several replies including one from a former
pilot who stated that the rudder of the P-47 was extremely effective
and yes he said it could be used to skid the nose into an attack
position even though the other aircraft was more manuverable. I should
point out that with eight .50 caliber machine guns it didn't take long
to produce extraordinary damage in the target aircraft so the Jug
pilots only had to skid for a second.
Corky Scott