Multiple-helicopter lifting system

[Kiltonge]

From Flight, December 1958.

... work presently being done by Vertol Aircraft Corporation, Morton, Pa.

Under a U.S. Army contract, the corporation is developing what is
officially known as the "multiple helicopter heavy lift system"—
a method of harnessing helicopters as teams of aerial workhorses
for short-haul lifts of heavy military vehicles and materiel.

The basic equipment for this purpose is an aluminium alloy
spreader frame to which the helicopters and cargo are attached by
cables. The ends of the frame, which is triangular in section, are
tapered to points and these are attached to the helicopters by ten-
foot cables.

Longer sling cables extend downwards from the ends
of the frame—which is 113ft long and weighs approximately 400 lb
—for attachment to the load being carried.

An electrical release system is provided to enable the pilots to
uncouple all members of the team in an emergency, or for normal
detachment; though normally only the command aircraft in a
multi-lift would make the release.

Loading and unloading may be done with the helicopters and
spreader frame (or.frames) in the air, with the aircraft just airborne
and the frames on the ground, or with everything grounded. The
Vertol test programme is to include trials with two, three and four
helicopters successively, and of co-ordination between flight and
ground crews during loading and unloading.

 

[Kiltonge]

I wonder if that was the inspiration for later Naval Air Systems contracts for studies into rigidly-coupled Stallions...

I think I prefer the Vertol approach, above, rather than Piasecki's ideas. Significantly the Vertol truss could be quickly deployed by any two helicopters, instead of having to take two off the front-line for interconnection of drive-shafts and flight-controls.

http://www.dtic.mil/dtic/tr/fulltext/u2/743516.pdf