Simplified VSTOL

The NACA saw promise in deflected-propeller-stream (DPS), vertical/short take-off and landing (VSTOL) aircraft 40 years ago, but couldn't make them work. Proponents of a recently patented DPS aircraft design believe they've gotten the bugs out and seem ready to challenge helicopters in short-haul, short-field operations.

Compared to helicopters, a fixed-wing aircraft delivers twice the lift/drag ratio in forward flight. Unlike tilt-rotor or tilt-wing designs, the DPS wouldn't require complicated power couplings between engines for safety should one engine fail. Instead, modern control electronics would adjust output from the remaining engines for controlled flight and hover. A four-to-nine passenger DPS operating conventionally could cruise 1,000 miles at 200 to 300 mph. Vertical take-off and landing would still deliver a 500-mile range.

C.R. Stone, EGR Co., 4955 Sorell Ave. North, Golden Valley, MN 55422-4137, (612) 588-3446.

Frugal drain valve

Draining condensates from compressed-air systems typically involves some loss of high-pressure air-not a lot at any one time, but it adds up. So much so, says its maker, that the System Saver(TM) loss-less automatic drain valve can pay for itself in one month of use on a typical high-capacity compressor.

A horizontal float within the collection tank signals a 10-psi poppet valve when to open and drain the tank and to close before the tank empties completely, preventing air loss. Designed for minimal maintenance, the System Saver line comprises corrosion-resistant materials including Viton(R) O-rings and seals.

Ingersoll-Rand Co., Dept. NR 577, 253 E. Washington Ave., Washington, NJ 07882-9988, (908) 689-5580.

Low-stress mixer

Axisymmetric power mixers fare poorly when dealing with high-resistance fluids. Shear zones and vortices impinging on mixer arms can quickly over-stress them. Prolific inventor James Kronberg's answer: an asymmetric mixer with balanced rotational moment. Its blades sweep out non-overlapping fluid volumes during rotation to minimize generation of unbalanced shear forces.

Caroline Teelon, Technology Transfer Office, Westinghouse Savannah River Co., Bldg. 773-41A, Aiken, SC 29808.