; some notes..............................Sturzflugbremsen (Dive brakes).
With the development of dive fighter aircraft, a new aerodynamic aid has found its way into aircraft construction: the dive brake, which is intended to limit the speed during a dive. It consists of simple resistance surfaces attached to the wing structure or fuselage, which are set to the lowest resistance for normal flight or which are completely retracted into the aircraft.
Before the dive begins, they are extended, i.e. adjusted transversely to the direction of flight and then generate additional resistance through which the fall speed is adapted or reduced to the requirements depending on the size of the brake. Figures 1 and 2 show the dive brake of the Ju-87 mounted under the wing in the retracted and extended state. This results in a reduction in the dive speed of around 150 km/h.
However, the reduction in the falling speed is not due to strength considerations - i.e. the Ju-87, the best-known dive bomber, can be recovered completely safely from the highest falling speed even with the brakes retracted and full flying weight - but rather takes exclusively tactical requirements into account. Only the brake makes it possible to get close to the target without the crew having to suffer from excessive acceleration forces when recovering, thereby impairing their ability to aim.
If an aircraft is in constant motion and is brought into a different flight attitude by operating the rudder, both the aircraft and the human body, i.e. the crew, due to its inertia, strives to remain in the old movement and its direction. The aircraft and crew therefore have to be brought into the new situation by force and are therefore understandably exposed to forces that occur in a similar way with all fast means of transport when taking a curve, starting off, etc.
The stress during the dive recovering increases the greater the speed and the smaller the radius of the circle flown during the dive recovering. If you set a maximum permissible load of 6 G, the fall speed and recovering radius are interdependent variables. The higher the speed, the larger the recovering radius must be if the permissible stress limit is not to be exceeded. The height above the ground at which the recovering begins also depends on the size of the recovering radius, and this means that recovering only needs to begin at a low height if the fall speed is kept sufficiently low.
Source: Sturzflugbremsen. Flugsport, Ausgabe Heft 4/1941.
Cheers. Raúl M
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