Engineering topics
Publications and source records attributed to Proll, A.
In the present article, several suggestions will be made for shortening the otherwise long take-off distance. For the numerical verification of the process, I will use a graphic method for determining the take-off distance of seaplanes.
There are two principal ways in which the total take-off distance (taxying plus hovering plus the first part of the climb) can be reduced to a minimum. These are: 1) taxying and hovering until the maximum speed has been attained close to the ground and then changing to a steep rapid climb; 2) lifting the airplane from the ground as soon as possible and then climbing at a relatively large angle of attack. These cases, as well as all the other conceivable combinations, can be expressed with a single basic formula, which is derived from the energy equation for rectilinear flight.
The following considerations determine the strength of airplane fabrics: 1. maximum air forces acting on the surfaces (including local stresses); 2. tensions produced in the fabrics, in the directions of both warp and filling; 3. factor of safety required. The question of the permissible depression of the fabric as affecting the aerodynamic requirements in regard to the maintenance of shape of the section, the tenacity and extensibility of the layer of dope, its strength and its permeability to water is almost as important.
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The general idea was to record the air pressure on the spot, that is, without intervening tubes, by some simple automatic registering device. This was therefore made in such small dimensions that it could be inserted into the wing between the ribs and stand in direct connection with the pressure openings. The results of different experiments are presented along with the best locations for locating the instruments for recording the pressure.
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