PZL-23 Karaś (SAMI).pdf

PZL.23B, '1' of N 0 64 Eskadry (Squadron) attached to 6

Pułku Lotniczego (Air Regiment), operating from Lwów

arly in the 'thirties, the Polish

Lotnictwo Wojskowe (Military

Aviation) requested a

replacement for its ageing

Potez 25 and 27 light

bomber/reconnaissance

biplanes. Państwowe Zakłady Lotnicze

(PZL - State Aviation Works) responded to

the 1931 specification, which requested an

all-metal light bomber powered by a

Bristol Pegasus air-cooled radial engine

able to carry a 600kg (13301b) bomb load.

It was required to attain a minimum speed

of 300km/hr (186mph) and to operate

from improvised airfields. PZL decided

that it could develop the new bomber from

its earlier P.13, a high performance six-

passenger light transport monoplane

lightplane had been abandoned when at an

advanced stage of detail design.

Apart from extensive redesign to the

fuselage, other changes were centred

around the addition of wing flaps and

provision for the mounting of both

offensive and defensive weapons. The wing

was designed by Franciszek Misztal, based

on an original stressed-skin concept which

had been tested earlier on the PZL. 19 high

performance touring aircraft. This wing,

tested on a static airframe in 1933,

presented serious problems and caused

delays in the construction of the first

On the first day of September, sixty years ago, the mighty German forces launched

their first Blitzkrieg against a neighbouring nation. While the exploits of Polish fighter

pilots received wide publicity, the close support and attack work carried out by a

small, light reconnaissance-bomber known as the 'Karaś' went completely

unnoticed. Suffering heavy losses, it saw extensive use during the first two weeks of

the Second World War. Surviving aircraft were eventually impressed into Rumanian

service and found themselves involved in the Axis' catastrophic events on the

Russian front, while the Bulgarian 'Tchaikas', an export derivative, was only

withdrawn from front line service in September 1944. Richard J. Caruana takes a

close look at an aircraft which is little known outside its country of origin.

by the Polish Skoda works: frequent

jamming of reduction gear, and fractures

in the crankshaft were the major causes.

After producing 40 examples of what had

by then become known as the P.23A

'Karaś', production switched to the P.23B;

its wing leading edge slats were removed

and it was re-engined with the much more

reliable 660/680hp Pegasus VIII which had

become available as from the summer of

1936. All P.23As were relegated to training

duties, being passed on to training schools

as soon as the 'B's became available.

By February of 1937, production of the

Karaś had reached the rate of 20 aircraft

per month. Thus the initial order of 200

examples was completed by September and

an additional order of 50 P.23Bs was placed

in February, 1938. Meanwhile, the P.23B

entered service with the 1st Air Regiment

in Warsaw and a total of 14 combat

squadrons, each equipped with ten Karaś,

were to be formed. Of these only twelve had

been completely when war broke out in

September 1939, as the other two were

equipped with the newer P.27 Los.

Technical Desciption

The Karaś B was an all-metal cantilever

monoplane powered by one Skoda Bristol

Pegasus VIII engine rated at 670 hp driving

a wooden two-bladed Szomański propeller.

Of note was the wing structure which was

one of the earliest metal sandwich

structures attempted on a production

aircraft. Misztal's wing (Patent N° 16,585,

June 20 1932), was built around a wide

central box-girder of two light duralumin

spars and corrugated duralumin sheet to

which a smooth duralumin skin was added

externally. A duralumin 'D' leading edge

and a stressed-skin multi-cell trailing edge

were attached, forming a wing structure

which became the hallmark of PZL on the

Karaś and most of their subsequent

prototype which, powered by a 570/590hp

Bristol Pegasus II M2, made its maiden

flight in the third week of August 1934.

Flight tests revealed rear fuselage vibration

and tail flutter, while crew accommodation

and visibility from the cockpit left much to

be desired.

Extensive modifications were

incorporated into the second prototype

(P.23/II) which flew early in 1935. The

fuselage was redesigned, the internal

bomb bay which made crew access

extremely difficult was removed while the

engine, now installed in a close-fitting

low-drag cowling, was lowered to improve

visibility. Improvements were also

introduced into the design of the wings

which received more effective slotted

ailerons and improved flaps. Automatic

slats were added to the leading edges of

the wings while the root fairings were

enlarged. This prototype, which proved

highly superior to its predecessor, was lost

during a bad weather landing accident and

had to be substituted in the test

programme by the third Karaś which was

completed in the middle of 1935.

Having reached a satisfactory standard,

an order for 200 P.23s was received by PZL.

Production started with a series of

problems, mainly centred around the

Pegasus II M2 engines built under licence

The pilot of a PZL.23 Karaś of Nr 22 Squadron makes his way into the front cockpit while the engine warms up in anticipation of another sortie (RJ Caruana Archives)

completely wasted when they could have

been put to better use in the bomber role,

notwithstanding that by the time of the

German invasion they were already

obsolescent.

On September 2 1939,18 Karaś from N°

64 and 65 squadrons performed their first

successful bombing of German targets

though at a great cost, as five aircraft failed

to return and a further three were

damaged. On the following day, 28 Karaś

from 21,22 and 55 Squadrons hit enemy

armour near Radomsko where they

claimed to have put 30% of German

vehicles out of action. Sorties continued

between September 4-8 by Karaś units in

conjunction with the four Los squadrons

concentrating on enemy armour in the

Radomsko-Piotrków region and around

Pułtusk, inflicting heavy losses to the

German 10th Army Group's 4th Armoured

Division and the Kämpf Armoured

Division. However the losses were such that

by the middle of September the operational

capability of Karaś units had become

insignificant. With the Russian

intervention of September 17, surviving

P.23s were flown to Rumania — some

twelve aircraft reaching that country —

and were impressed into service into the

Rumanian Air Force.

Though not a brilliant fighting machine,

the PZL.23 Karaś has found its niche in

history as one of the first aircraft to oppose

designs. Fuel was contained in two 2301t

tanks fitted between the wing spars in the

centre section and two 501t tanks fitted aft

of the rear spar. An additional 251t tank

was housed in the front fuselage, ahead of

the windscreen. The tail unit was

structurally very similar to the wing. The

fixed landing gear consisted of two main

PZL oleo legs enclosed in streamlined

fairings fitted with Dunlop 775x240mm

wheels, and a sprung tailskid.

The oval-section fuselage was similarly

strengthened internally by corrugated

sheeting under its stressed-skin

construction. The pilot sat in the front

within an enclosed cockpit while the

observer, provided with removable dual

controls, sat behind. This second crew

member doubled as bomb aimer/gunner,

descending into the ventral gondola which

was equipped with bomb-release gear and

camera in the forward section and a

Vickers 'F' Type 7.7mm machine gun at the

rear firing downward. Another Vickers gun

was provided for a third crew member who

sat in an open cockpit; the Vickers were

sometimes substituted by indigenous

7.9mm Km Wz37 Szczeniak machine guns.

The pilot could use a fixed 7.9mm Km Wz

33 fitted to the starboard side of the

fuselage, firing through the engine

cylinders' banks and propeller arc. Up to a

maximum of eight 100kg bombs could be

carried attached to racks under the wing

centre-section although the bomb load was

usually restricted to 700kg.

for 42 machines was placed with PZL.

Some thirty of this second order had

been delivered by August 1939, while eight

were awaiting delivery and a ninth ready to

leave Airframe Plant N° 1 at Warsaw-

Okęcie. Crews from N° 41 Squadron, Polish

Air Force, were ordered to pick these P.43Bs

on the second day of the war to replace

losses of P.23 Karaś. Of these, only five

could be retrieved as the others had been

destroyed on the ground in a German

attack against the Okęcie airfield.

As early as 1936, Prauss had begun

radial were ordered for the Polish Air Force

while a Gnome-Rhone powered version

was being considered by Bulgaria.

Deliveries to the squadrons had been

scheduled for early 1940 but production

had hardly got underway at the time of the

German invasion.

In Combat

114 P.23s were flown by first-line units

during the September Luftwaffe

onslaught, and an additional 11 machines

(including the five PZL. 43s) were received

An Export Model

Bulgaria showed great interest in the P.23

Karaś and placed a order for 12 machines

early in 1936 specifying the need for a

more powerful engine and a second

forward firing gun. To offset the centre of

gravity movement resulting from the

heavier Gnome-Rhone 14N-01 engine, the

main cabin had to be redesigned and the

rear fuselage lengthened by 27cm. The

original third prototype (P.23/III, by then

registered SP-BMF) served as test bed for

the new engine. The first aircraft, which

had been designated PZL.43 'Tchaika'

(Seagull), to be delivered to Bulgaria were

fitted with the Gnome-Rhone 14Kfs

engine due to delays of shipments from

France until the 14N-01s became

available. These aircraft gained an

excellent reputation and a second order

A stricken PZL.23 Karaś of N°41 Squadron is inspected by Luftwaffe personnel who landed for this purpose near the crash site (RJ Caruana Archives)

work on a Karaś replacement to be

designation of P.46 'Sum'. A twin fin and

rudder tail was devised to provide the rear

gunner with a better field of fire while the

gunner's ventral gondola could be

retracted. A production P.23B was taken

off the line for conversion, designated P.42.

A true prototype, the P.46/I, flew in

October 1938 and a second was available

by spring of the following year. Results

were so encouraging that 300 Sum As

as replacements. In spite of the numerical

and technical inferiority of the Polish

aircraft, they managed to put up a brave

defence. As soon as hostilities began N°

21,22,55,64 and 65 equipped with Karaś,

together with the four Los Squadrons,

were formed into the Bomber Brigade

under the direct command of the Polish

Armed Forces. Karaś of N° 24,31,32,34,

41,42 and 51 Squadrons were attached to

one each of the seven land army units in

the reconnaissance role and put under

their complete command. The latter were

the mighty Luftwaffe during World War II.

Its limited capabilities in the face of an

opponent of gigantic proportions could

only be partially offset by the tremendous

valour which its crews displayed in the

defence of their homeland. Most of them

lost the battle, but not the war, as they fled

their country to continue the fight with

whoever could hit back, helping in no

small way in the Allied war effort.

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