Method and apparatus for measuring pneumatic differential drag forces

A differential drag force apparatus for detecting air pressure forces on an object moving through the air and for initiating a signal when exposed to a sustained air pressure force of a predetermined magnitude, the apparatus including a supply of pressurized fluid, the apparatus comprising:

• (a) a sensor means including a drag-sensing body to detect a differential drag force of a predetermined magnitude, the body responding to the drag force by relative movement of the body with respect to the object;
• (b) a pressure regulator responsive to the relative movement of the body, for regulating the pressurized fluid, the regulator including,
• (i) a regulating chamber, and
• (ii) a sealing means for sealing off the supply of pressurized fluid from the regulating chamber, said sealing means opening to permit pressurized fluid from the supply to enter said regulating chamber when the pressure in said regulating chamber is less than the pressure in the supply;
• (c) a trigger having a spring-biased firing assembly, for initiating the signal;
• (d) an activation system responsive to said pressure regulator, for enabling the firing assembly to initiate the signal, said system having,
• (i) a bellows, for receiving the regulated pressure from said regulator,
• (ii) an orifice, for permitting the pressurized fluid within the bellows to escape at a predetermined rate, and
• (iii) an activation piston displaceably contained within said bellows, said piston displaced to an enabling position when the uniform pressure within the bellows reaches a predetermined level, thereby enabling said trigger to initiate the signal;
• and
• (e) a priming system to cock the firing assembly and to initiate the operation of said regulator.

A method for detecting differential drag forces and initiating a signal when exposed to a sustained air pressure force of a predetermined magnitude, said method comprising:

• placing in the air stream a body which will respond by movement to an air pressure force of a predetermined magnitude;
• releasing a uniform pressure gas in response to the movement of the body into a chamber that has a restricted outlet;
• sensing the pressure level within the chamber as the gas is allowed to escape through the restricted outlet at a predetermined rate;
• and
• initiating a signal when the pressure level within the chamber exceeds a predetermined level.