Junkers Ju 87
Design & Structure
The Ju 87 was a single-engined all-metal cantilever monoplane. It had a fixed undercarriage and could carry a
two-person crew. The main construction material was duralumin, and the external coverings were made of Duralumin
sheeting. Parts that were required to be of strong construction, such as the wing flaps, were made of Pantal
(a German aluminum alloy containing titanium as a hardening element) and its components made of Elektron.
Bolts and parts that were required to take heavy stress were made of steel.
The Ju 87 was fitted with detachable hatches and removable coverings to aid and ease maintenance and overhaul.
The designers avoided welding parts wherever possible, preferring moulded and cast parts instead. Large
airframe segments were interchangeable as a complete unit, which increased speed of repair.
The airframe was also subdivided into sections to allow transport by road or rail. The wings were of standard
Junkers double-wing construction. This gave the Ju 87 considerable advantage on take-off; even at a shallow
angle, large lift forces were created through the aerofoil, reducing take-off and landing runs.
In accordance with the Aircraft Certification Center for "Stress Group 5", the Ju 87 had reached the acceptable
structural strength requirements for a dive bomber. It was able to withstand diving speeds of 600 km/h (370 mph)
and a maximum level speed of 340 km/h (210 mph) near ground level, and a flying weight of 4,300 kg (9,500 lb).
Performance in the diving attack was enhanced by the introduction of dive brakes under each wing, which
allowed the Ju 87 to maintain a constant speed and allow the pilot to steady his aim. It also prevented
the crew from suffering extreme g forces and high acceleration during "pull-out" from the dive.
The fuselage had an oval cross-section and housed a water-cooled inverted V-12 engine. The cockpit was protected
from the engine by a firewall ahead of the wing center section where the fuel tanks were located. At the rear
of the cockpit, the bulkhead was covered by a canvas cover which could be breached by the crew in an emergency,
enabling them to escape into the main fuselage. The canopy was split into two sections and joined by a strong
welded steel frame. The canopy itself was made of Plexiglas and each compartment had its own "sliding hood"
for the two crew members.
The engine was mounted on two main support frames that were supported by two tubular struts. The frame structure
was triangulated and emanated from the fuselage. The main frames were bolted onto the power plant in its top
quarter. In turn, the frames were attached to the firewall by universal joints. The firewall itself was
constructed from asbestos mesh with dural sheets on both sides. All conduits passing through had to be
arranged so that no harmful gases could penetrate the cockpit.
The fuel system comprised two fuel tanks between the main (forward) and rear spars of the (inner) anhedral wing
section of the port and starboard wings, each with 240-litre (63 US gal) capacity. The tanks also had a
predetermined limit which, if passed, would warn the pilot via a red warning light in the cockpit. The fuel was
injected via a pump from the tanks to the power plant. Should this shut down, it could be pumped manually using
a hand-pump on the fuel cock Armature. The powerplant was cooled by a 10-litre (2.6 US gal), ring-shaped
aluminium water container situated between the propeller and engine. A further container of 20-litre
(5.3 US gal) was positioned under the engine.
The control surfaces operated in much the same way as other aircraft, with the exception of the innovative
automatic pull-out system. Releasing the bomb initiated the pull-out, or automatic recovery and climb, upon the
deflection of the dive brakes. The pilot could override the system by exerting significant force on the control
column and taking manual control.
The wing was the most unusual feature. It consisted of a single center section and two outer sections installed
using four universal joints. The center section had a large negative dihedral (anhedral) and the outer surfaces
a positive dihedral. This created the inverted gull, or "cranked", wing pattern along the Ju 87's leading
edge. The shape of the wing improved the pilot's ground visibility and also allowed a shorter undercarriage
height. The center section protruded by only 3 m (9 ft 10 in) on either side.
The offensive armament was two 7.92 mm MG 17 machine guns fitted one in each wing outboard of undercarriage,
operated by a mechanical pneumatics system from the pilot's control column. The rear gunner/radio operator
operated one 7.92 mm MG 15 machine gun for defensive purposes.
The engine and propeller had automatic controls, and an auto-trimmer made the aircraft tail-heavy as the pilot
rolled over into his dive, lining up red lines at 60°, 75° or 80° on the cockpit side window with
the horizon and aiming at the target with the sight of the fixed gun. The heavy bomb was swung down clear of
the propeller on crutches prior to release.
Sources:
Gunston, Bill - The Encyclodepia of the Worlds Combat aircraft, 1976, Chartwell Books, Inc., New York
Brown, Eric, Captain - Wings of the Luftwaffe, 1979, Airlife Publishing Ltd., Shrewsbury
Gunston, Bill & Wood, Tony - Hitler's Luftwaffe, 1977, Salamander Books Ltd., London
Donald, David - The Complete Encyclopedia Of World Aircraft, 1997, Brown Packaging Books Ltd., London
Wikipedia - Junkers Ju 87
Gunston, Bill - The Encyclodepia of the Worlds Combat aircraft, 1976, Chartwell Books, Inc., New York
Brown, Eric, Captain - Wings of the Luftwaffe, 1979, Airlife Publishing Ltd., Shrewsbury
Gunston, Bill & Wood, Tony - Hitler's Luftwaffe, 1977, Salamander Books Ltd., London
Donald, David - The Complete Encyclopedia Of World Aircraft, 1997, Brown Packaging Books Ltd., London
Wikipedia - Junkers Ju 87