7-3 PANZER TRACTS - PANZERJAEGER (7.5 cm Pak 40.4 TO 8.8 cm WAFFENTRAEGER) DEVELOPMENT AND EMPLOYMENT FROM 1939 TO 1945.pdf

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PANZER TRACTS No.7-3
Panzerj aeger
(7.5 em Pak 40/4 to 8.8 em Waffentraeger)
development and employment from 1939 to 1945
Created by Thomas L. Jentz
and Hilary Louis Doyle
Featuring ultra-accurate, as-built 1/35th scale drawings of the
7.5 em Pak 40/4 aufRSO, "Hornisse/Nashorn", and 8.8 em
Steyr-Waffentraeger
Front Cover Photos: One of the two completed Pz.Stl. fuer 12.8 em K.40 outside an assembly hall at
Alkett on 9 March 1942. After being issued to a Panzerjaeger-Zug that was assigned to Panzerjaeger-
Abteilung (Stl.) 521, the two Pz.Stl. were nicknamed "Max" and "Moritz". (Rhm)
Scale prints by Hilary Louis Doyle, drawn on the board originally in 1/24 scale, have been reduced to 1/35
scale using a 3000 mm long scale bar with graduations at 1000 mm intervals.
The scale prints of the 7.5 em Pak 40/4 auf RSO, Hornisse, and 8.8 em Steyr-Waffentraeger were drawn
at full scale using a CAD program and printed at reduced scale. Over 250 hours were expended to mea-
sure surviving examples in detail to produce extremely accurate drawings within the tolerances allowed
to the original assembly firms.
Thanks are especially due to Karlheinz Muench (12), Detlev Terlisten (2) and Thomas Anderson (2) for
providing copies of rare and unique photos. Photos were also obtained from the Bundesarchiv-Bildarchiv
(5) and Militaerarchiv (11), The Tank Museum (9), the National Archives (6), the Patton Museum, Fort
Knox (2), and the Ordnance Museum (Rheinmetaii-Collection) (9).
Special thanks also go to Frank, Ed, William, and Mario for supporting our efforts in measuring details
on surviving museum pieces and artifacts to create accurate as-built drawings.
Published by
Panzer Tracts
P.O.Box 334
Boyds, MD 20841
©
Copyright Thomas L. Jentz 2006
ISBN 0-9771643-3-0
www.panzertracts.com
All rights reserved. No portion of this
publication may be reprinted or reproduced
in any fashion or by any means without the
express written permission of the publisher.
Introduction
This
last
volume of the
Panzer Tracts 7
series cov-
ers eight
different
self-propelled guns created
for use by
Panzerjaeger
(tank
destroyer) units.
There
is no common
thread
between
these various
design projects.
Some were
mounted
on existing
chassis
(such as the
7.5 em Pak 40/4
aufRSO
and the
7.5 em Pak 44 auf3 to Zgkw.).
Others
were created with
newly designed
chassis,
but
still
uti-
lized
already existing automotive components (such as
the
Panzerjaeger Hornisse, Waffentraeger,
and
the
Pz.Sfl.
fuer 12.8 em Kan.40).
However,
they
all
had
two
features
in common - open
tops
so
that the
crews could observe and
hear much better than tank crews and
light
armor
to
keep
the weight
down
for
better mobility.
In all cases
these
Selbstfahrlafetten
(self-pro-
pelled carriages) were
more
effective weapon systems for
knocking out
tanks than the
same gun on a
towed carriage.
As
reported by the user
organizations,
high
velocity anti-
tank guns weighing
more than
a
ton
were
too heavy for the
crews to
move to
alternative firing
positions
and were
too
big
to
hide
in front
line positions
with
the
infantry.
But,
as
proven
by their kill-to-loss records, these
same
heavy
guns
mounted on self-propelled
chassis
could
be
very effective-
ly used in
counterattacks
to
strike
the flank of
enemy
tank
attacks and also could
rapidly
change
positions
when
they
themselves
came under fire.
From
1943 to the
end of
the
war,
Wa Pruef 4
(ar-
tillery design office)
kept
insisting
that these
Selbstfahr-
lafetten
have
two features: 360
degree traverse
for all-
round fire and the
gun
be dismountable
for emplacement
on the ground. While
the
first
requirement
was achieved
with the
7.5 em Pak 40/4 aufRSO
and
8.8 em Pak 43 auf
Waffentraeger,
the second
requirement
to
dismount
the
gun onto a towed carriage
kept
getting
in the
way
of
com-
pleting
projects
for
mass production. This requirement
to
dismount the gun is
not understood.
The
main
advantage
appears to be that the gun could still
be
kept in action
when the vehicle
broke down. But,
couldn't the same
objective
have
been
met
simply
by
placing
the
7.5 em Pak
40
with its original wheeled carriage on an
unmodified
RSO
Gust
like
the
British
mounted their 2 and 6
pounder
anti-tank guns "portee" on trucks)?
But
"simple"
solutions were not acceptable to Ger-
man engineers. Fortunately some of the correspondence
and records of meetings between
Wa Pruef
(ordnance de-
sign office)
and
engineers from the
detail design
firms have
survived to provide
us
with some insight into the basis for
their design decisions. All reports that
have
been found
were translated and included in the text to provide clues
to the circumstances forcing them to take certain design
directions. Even so, our inability to now question these
key individuals leaves us with some unresolved contradic-
tions. For example, why did they abandon the single axle
carriage for the
8.8
em
Pak 43/41
in favor of the heavier
dual
axle carriage for the
8.8 em Pak 43
-
and then state
that a single axle carriage was
needed
for the
dismounted
7.5 em Pak 42
because
there was a shortage of heavy tow-
ing vehicles needed to tow a twin-axle carriage?
A true understanding
of
the
value of
the
Panzer-
jaeger
can
be
gained from experience
reports
written
by
unit
commanders
close to the time
when
the
action oc-
curred.
Based
on
their personal
experience
in
combat, the
observations and advice contained in these wartime reports
totally contradict
misinformed
statements from self-pro-
claimed experts whose avid
interest
can
hardly
compensate
for
their lack
of experience,
lack
of
technical
knowledge,
and inability
to conduct
objective weapons system analy-
ses.
If the
12.8 em Kanone 40
was such a superior
long-
range
tank killer, why
was
it being used to knock
out T34
tanks
at
1000 to 1500 meters - ranges in
which it could
itself be penetrated by the 7.62
em gun on
the T34?
If the
8.8 em Pak 43
was so effective at
killing tanks
why
did
a
company
commander
refuse to engage a
battalion
ofT34
tanks?
If the
7.5 em Pak 40/4 aufRSO
was such a great
idea,
why
did the units using it
report:
Although the
Pak
40 auf RSO
can be immediately brought into action and is
maneuverable, it
has
been a complete failure.
Over one thousand hours were
spent carefully
measuring and drawing
all
the details
on a surviving
Pan-
zerjaeger "Hornisse"
and a
7.5 em Pak 40/4 aufRSO
to
create ultra-accurate
as-built
drawings. In
addition,
about a
hundred
"clean"
photos taken during the
Wflr were
carefully examined to
determine precise details
of
bits now
missing from the "survivors" and to
determine
the exact
order
in
which
modifications
were
introduced into
the
production
series.
It
is this careful and thorough study of
details,
combined with over 37 years spent searching for
all the surviving
documents, drawings, and photos,
that
makes Panzer
Tracts
the
ultimate
in
historically
accurate
documentation.
Measured and drawn at 1: 1, the
drawings
are
printed at the
popular 1:35
scale. Even so, there
is no loss
in detail
with
this
reduction in scale
because
the software
now
being used
to create the printing
plates is not
a
line-
by-line
printer. When we draw a circle, the software draws
a circle
using
the center and
radius.
When we
draw
an arc,
it
draws an arc
using
the two ends and center
point.
This is
vastly superior to the old technique of
laying down
pixels
whenever the line printer crosses a
drawn
object, resulting
in saw-toothed edges on curves and slanted
lines.
Com-
pare the super-clean drawings
in
Panzer Tracts 5-3, 7-1
,
7-2, 7-3
,
9-3, and 15-2 with the older
line
printer technique
used to print cad drawings in Panzer Tracts 1-1
,
1-2, 5-1
,
13, 20-1
,
and 20-2.
P.S. The crew cab for the
7.5
em Pak
40/4 aufRSO
was
made out of thin sheet metal- not armor.
7-169
7.5
em
Pak 40/4 aufRSO
Following
initial
project discussions with
Wa
Pruef,
Rheinmetall completed a conceptual design draw-
ing H Sk B 82838 on 28 May 1943 of
a
7.5
em
Pak
40
mounted on a pedestal on top of a modified
RSO
chas-
sis. Planning was well advanced when this project was
discussed
in
Speer's conference with Hitler on 4/5 August
1943:
Hitler is pleased that
Wa Pruefworking
together
with
Steyr has developed the
Pak 40 auf Raupensehlep-
per Ost.
Firing trials have
started
and troop trials are to
be quickly organized. This also applies to the proposed
Sehlittenanhaenger mit Pak 40
(towed sled).
On 2 September
1943,
Wa Pruef
4
reported the
basic design ideas
for the
7.5
em
Pak
40
aufRSO
and
project status, as follows:
Panzerabwehr
(anti-tank)
experience
reports
con-
tinuously
complain
that because of
its
weight the sehweren
Panzerjaegerkanonen mot Z
can't
be moved by the
crew
on
the battlefield. Changing firing positions and moving
short stretches can
only be done, with assistance from tow-
ing
vehicles
that must first be brought forward.
In
addi-
tion to the loss of time,
changing
positions under
enemy
fire usually results in the
loss
of men and
equipment.
Easy
maneuverability in
combat
is a requirement that must be
demanded for any towed
Pak
with
limited
traverse associ-
ated with its
Spreizlafette
(split trails). Based on frontline
experience
in the East, this requirement is met only by
guns that weigh up to I 500 kg, i.e.
,
leiehten
and
mittleren
Pak.
Based
on
these facts,
Wa Pruef 4
initiated
studies
to determine under
which specifications and which
meth-
ods
it
would
be possible to make it
easier
to move the
7.5
em
Pak 40.
Wa
Pruef
4
started with
the idea
of
creating
a
mechanized
Pak
that
can immediately fire
from the
vehicle
and
pull
out
of
enemy fire
more
rapidly
than is
possible
with
the towed
Pak
weighing
I.5 tons.
The
Raupensehlepper Ost
serves
as the
tow-
ing
vehicle
for the
7.5
em
Pak 40.
This led to the idea
of
mounting the gun
with
upper
carriage
on the
RSO
and,
if
possible, achieve all-round
fire
and dismountability.
Work-
ing together with Rheinmetall-Borsig
(the
development
company
for the
7.5
em
Pak
40), a
Soekel
was
designed to
mount the
Pak 40
with
its upper
carriage
on the
RSO.
At
the
same
time the firm Steyr-Daimler-Puch A. G. (develop-
ment
company
for the
RSO)
was
pulled in to possibly use
an
unmodified
RSO
for this purpose.
The first trials, made to determine
if
it was pos-
sible
to fire to
the
side
from the
RSO,
were
completely
successful.
The
Fuehrerhaus
was
dropped
so
that the
firing height could be
lowered
to 1800 mm from
2100 on
the original design (which is now more than
200
mm lower
than the firing height of the available
Pak-Sjl.
on
Pz.//
and
38(t)
chassis,
which have a limited traverse
and aren't
loved
by the troops because of their height). Otherwise
nothing is
changed
on the
RSO
except
the
Pritsehen-
aujbau
was changed
so
that 30 rounds of ammunition
could
be stowed (which is the
same
amount that is
carried
when an
RSO tows
this
Pak).
For the first time a
successful
trial has been
completed with
a gun mounted on a previously
available
chassis which
has both all-round
fire
and
can
be dismount-
ed.
This design also has
significant
advantages
for
Pak
40
production because the
gun with
upper
carriage can
be
Above: At an early project stage in June 1943, Steyr conducted trials with an
unmodified
7.5
em Pak 40 mounted on Versuchs-RSO (trial
RSO)
with Fgst.Nr. V4.
(HLD)
7-170
Above: For the first trial model a 7.5 em Pak 40 was mounted on a relatively high pedestal to clear the
sheet-metal crew cab and enable all-round traverse of the gun. (HLD) Below: Firing trials were con-
ducted with this first Versuchs 7.5 em Pak40/4 auf RSO on 13 July 1943. (HLD)
7-171

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