Firing through prop hub

[Jeff Wolfe]

From Jeff Wolfe <JTW...@psuvm.psu.edu>

During early WW2, some aircraft had cannon that fired throught the hub of
the propeller (and the engine?) how did they do this? Was there a special
design of crankshaft that was straight? Did it only work on radials,
or could v and inverted V engines use it also?

Thanks for the info..

-- Jeff Wolfe
JTW...@psuvm.psu.edu Jefw...@endor.cs.psu.edu

"The more money you have, the faster you go.." -Unknown

[Charles K. Scott]

From Charles...@dartmouth.edu (Charles K. Scott)

In article <1992Feb21....@cbnews.cb.att.com>
JTW...@psuvm.psu.edu (Jeff Wolfe) writes:

> During early WW2, some aircraft had cannon that fired throught the hub of
> the propeller (and the engine?) how did they do this? Was there a special
> design of crankshaft that was straight? Did it only work on radials,
> or could v and inverted V engines use it also?

This question was asked before. The answer was that the BF-109E,
starting with models produced after the Battle of Britain but not
during it, had a 20mm canon installed between the banks of the inverted
Daimler V-12 and firing through the prop hub. It could to this because
the prop was not directly connected to the engine crankshaft but was
spun by a reduction gear box that offset the propellor and put it in
line with the gun barrel. Later Messershmidts used a 30mm canon in the
same place. The installation was not considered to be very effective
as it was difficult to service and didn't carry much ammunition.

Corky Scott

[Peter Shyvers]

From pshy...@pyrnova.pyramid.com (Peter Shyvers)

In article <1992Feb21....@cbnews.cb.att.com> JTW...@psuvm.psu.edu (Jeff Wolfe) writes:
>
> During early WW2, some aircraft had cannon that fired throught the hub of
>the propeller (and the engine?) how did they do this? Was there a special
>design of crankshaft that was straight? Did it only work on radials,
>or could v and inverted V engines use it also?
>

I don't recall any radial engines specifically with this, but I could be
very wrong. From cutaways, I seem to recall a setup wherein the prop was
gear-driven, rather than direct attachment to the engine crankshaft. The
gear was offset - above - the engine, and the cannon sat atop the engine
poking its snout out thru the gear and prop hub.

Anyone recall if the P39 Aircobra (mid-engined) was cannon-equipped, or did
it just have the usual US armament of 50-cal. machine guns?

[mod.note: The Bell P-39 Airacobra had a 37mm (later, 20m) cannon firing
through the hub; it was a bit more peculiar in having the engine located
behind the pilot, driving the propellor through a driveshaft. - Bill ]

[ele...@csc.canterbury.ac.nz]

From ele...@csc.canterbury.ac.nz

In article <1992Feb21....@cbnews.cb.att.com>, JTW...@psuvm.psu.edu (Jeff Wolfe) writes:
> From Jeff Wolfe <JTW...@psuvm.psu.edu>
> During early WW2, some aircraft had cannon that fired throught the hub of
> the propeller (and the engine?) how did they do this? Was there a special
> design of crankshaft that was straight? Did it only work on radials,
> or could v and inverted V engines use it also?

I've read about at least one installation which had a V-engine driving the prop
through gears, with the cannon between the cylinder banks of the engine - I
presume this type of arrangement was the norm. As for radial engines, the same
setup would be needed (I don't think you can build a radial with a straight
crankshaft), however I can't recall any radial engined aircraft with a cannon
firing thru the prop hub - or for that matter a radial engined aircraft with an
indirectly driven prop.

*********************************************************
Chris Kaiser
*********************************************************
"When you're fresh out of lawyers
You don't know how good it's gonna feel"
- Al Stewart, 1988
*********************************************************

[steve hix]

From fid...@concertina.Eng.Sun.COM (steve hix)

>From Jeff Wolfe <JTW...@psuvm.psu.edu>
>
> During early WW2, some aircraft had cannon that fired throught the hub of
>the propeller (and the engine?) how did they do this? Was there a special
>design of crankshaft that was straight? Did it only work on radials,
>or could v and inverted V engines use it also?

The only aircraft that I can think of that fired something through
the properllor hub had inline engines. The ones that come to mind
are the Bell P-39 (and possibly the P-63) and some models of the
Bf-109. There were probably others.

The trick for doing this lies in the fact that at least some inline
installations also used some sort of reduction drive to turn the
prop, rather than running off the end of the crankshaft.

If the reduction gear's hub was offset from the centerline of the
engine, you could use a hollow shaft and toss something through
it.

Firing through the crankshaft might be doable, but it sounds like
a needlessly-complicated way to get the job done.

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[Stan Brown]

From st...@dixie.com (Stan Brown)

ele...@csc.canterbury.ac.nz writes:

>From ele...@csc.canterbury.ac.nz

>In article <1992Feb21....@cbnews.cb.att.com>, JTW...@psuvm.psu.edu (Jeff Wolfe) writes:
>> From Jeff Wolfe <JTW...@psuvm.psu.edu>
>> During early WW2, some aircraft had cannon that fired throught the hub of
>> the propeller (and the engine?) how did they do this? Was there a special

>I've read about at least one installation which had a V-engine driving the prop

>through gears, with the cannon between the cylinder banks of the engine - I

In addation to this there was the P-39 (there is a wonderfule
display of it in the Air Force Musem in Dayton). In thi design
the engine was aft of the cockpit with a driveshaft running foward.
The cockpit was almost in the center of the plane & the canon was
foward of this. Up forn the canaon canon shell wen thruogh a
hole in the center of the pro, while the drivesahft drove
the prop through a set of spur gears. The derivesahft ran under the
cockpit. I don't believe having the driveshaft running almost
between thier legs was very popular withthe pilots :-)

Stan

--
Stan Brown P. C Design
Home (404)-299-2225 Atalanta Ga. (USA)
Work (404)-3632303

[michael smith]

From michae...@f842.n680.z3.fido.zeta.org.au (michael smith)

Original to: JTW...@psuvm.psu.edu
In a message of <21 Feb 92 02:48:12>, JTW...@psuvm.psu.edu (3:713/602)
writes:

J> JTW...@psuvm.psu.edu (Jeff Wolfe), via *IXgate 3:713/602
J>
J>
J> From Jeff Wolfe <JTW...@psuvm.psu.edu>
J>
J> During early WW2, some aircraft had cannon that fired throught the hub
J> of the propeller (and the engine?) how did they do this? Was there a
J> special design of crankshaft that was straight? Did it only work on
J> radials, or could v and inverted V engines use it also?

Geared propellor shafts... or if a radial, then a hollow one with the cannon
behind the engine. Certainly the BF109 variant had a geared propellor shaft
and the cannon (30mm but MG-what?) sat in the V of the engine.)

J> Thanks for the info..

My pleasure :)

J> -- Jeff Wolfe
\`miff` /|\
--- ScanMail 0.60bta
* Origin: That Which Is Not, ST in SA. 61-8-232-5722 (3:680/842)

[jukl...@kontu.cc.utu.fi]

From jukl...@kontu.cc.utu.fi

In article <1992Mar3.0...@cbnews.cb.att.com>, michae...@f842.n680.z3.fido.zeta.org.au (michael smith) writes:
> Geared propellor shafts... or if a radial, then a hollow one with the cannon
> behind the engine. Certainly the BF109 variant had a geared propellor shaft
> and the cannon (30mm but MG-what?) sat in the V of the engine.)
>

Also several Soviet planes had this arrangement. Unfortunately
I cannot remember any details just now but at least Yakovlev types
had a cannon in the nose hub.

Lehtonen JV

[Suicidal Freshman]

From yuq...@bvc.edu (Suicidal Freshman)

In article <1992Mar13....@cbnews.cb.att.com>, jukl...@kontu.cc.utu.fi writes:

>> Geared propellor shafts... or if a radial, then a hollow one with the cannon
>> behind the engine. Certainly the BF109 variant had a geared propellor shaft
>> and the cannon (30mm but MG-what?) sat in the V of the engine.)

> Also several Soviet planes had this arrangement. Unfortunately
> I cannot remember any details just now but at least Yakovlev types
> had a cannon in the nose hub.

The Soviet concept of the WWII era was two or more machine guns plus a
"powerful" cannon, and as I recall most of them shoots through the hub. La-5,
La-7, and La-9 had them, so did MiG-3 and MiG-5 (can't remember higher numbered
MiGs, but I can safely say MiG-15 didn't have it.). It also seemed to me that
the Il-2 had them too.

SF
bvc
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