(Soft Touchdown and Rapid Rigging/Derigging Air Drop System)

The Soft Touchdown And Rapid Rigging/Derigging System (STARRDAS) achieves soft landing of airdropped cargo by retracting the cargo slings within the last second before touchdown.

Program goals for STARRDAS included:

  • Demonstrating the feasibility of soft landing cargo of 10,000 lbs suspended weight,
  • Demonstrating Roll On/Roll Off (RORO) capability, and
  • Gathering data about the interaction of cargo and parachutes during retraction.

All program goals were realized. Sink rate of a 16-foot Type V airdrop platform, ballasted to 10,000 lbs, was reduced from 25 ft/s to less than 8 ft/s at touchdown in Airdrops #2 and #3. Landing at ?8 ft/sec is equivalent to a free-fall from 12 inches, which vehicles such as the HMMWV can tolerate without any special preparation, even when loaded with supplies and weapons. This dramatic reduction in landing energy supports the goals of the Army’s RRDAS (Rapid Rigging/Derigging Airdrop System) by making paper honeycomb unnecessary.

The retractor is lashed to the top of the platform, in a position where it can be straddled by a vehicle. Four sling cables radiate from the retractor to sheaves near the corners of the platform, where the cables are redirected toward the confluence point above the cargo.

An electronic controller within the retractor monitors barometric pressure and temperature, as well as a ground sensor. The controller can compute air density, sink rate and the ideal height to initiate retraction. Retraction is powered by nitrogen gas stored at 3500 psi in DOT-rated composite pressure vessels. The electronic controller also monitors the retraction (in real time) and can modulate the nitrogen flow to cause sink rate to dwell at a predetermined rate. This dwell period increases the probability of soft landing despite wide tolerances on terrain slope, platform attitude and height sensing.

To prepare the cargo slings for retraction, the slings are allowed to extend 20 feet during parachute deployment at a controlled load. Prior to sling extension, the distance between the cargo and canopy is the same as for systems without the retractor, thus avoiding over-rotation at tip-off.

STARRDAS has demonstrated a reusable method to soft-land airdropped cargo.


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Mechanical & Electromechanical Engineering