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elevators and gives the tail a positive lift. At the same time the trim of the airship will keep its nose elevated so that there will be the familiar dynamic lift on the hull surface and the vertical component of the propeller thrust to assist the ascent. In this cas:e-e - 

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d. The most diffic•lit maneuver which confronts the pilot is the landing. This operation may b~ divided into three parts, as• follows: 

(1) Weigh-off. 

(2) Approach. 

(3) Arrival at the landing party. 

e. Weigh-off is made at a safe altitude (1,000 feet for large airships, 250 to 500 feet for smaller ones). For this maneuver controls are 

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placed in neutral and air speed reduced to as low a speed as possible. The airship will quickly assume an attitude determined by the trim, which can be read from the inclinometer. At the same time the pilot can notice whether the airship is rising or descending statically. It is useless to bring the airship to an even keel to eliminate dynamic lift caused by unavoidable residual speed incident to idling propellers, as this would, in reality create a dynamic thrust on the tail surfaces. As a result of the knowledge of condition of the airship derived from weigh-off and after due consideration of existing meteorological condi› tions, the pilot is ready to make the approach. 

f. The principal object of the approach is to determine in advance of the arrival at the party the behavior of the airship at landing speed. Figure 26 gives a graphical picture of the approach. 

(1) From the altitude of weigh-off the airship is brought quickly to the altitude of approach. This varies from 150 feet for a nonrigid to 500 feet for a large rigid, depending in some measure on gustiness of the atmosphere. During the descent the pilot arranges the trim he estimates to be necessary to make the landing. On arrival at the 

