The US Air Force is expressing interest in the Piasecki Aircraft Vectored Thrust Ducted Propeller (VTDP) which the US Navy plans to flight test using a modified compound Sikorsky YSH-60F Seahawk helicopter under a new advanced technology demonstration (ATD) contract.


Piasecki has secured a $26.1million contract to integrate, test and flight demonstrate its VTDP concept, following the ground testing of a structural test article. Component fabrication has started and will end with a flight demonstration at the US Navy's Patuxent River test air station in 2003/04. A compound helicopter is fitted with wings and/or additional propulsion to improve performance.

The programme has caught the attention of USAF's Air Combat Command which, from 2007, is to analyse alternatives to replace or enhance its HH-60G Pave Hawk combat search and rescue (CSAR) helicopters (Flight International, 22-28 February). It is looking at a similar compound demonstration using a VTDP-equipped HH-60, depending on the USN programme's success.

"We foresee potential operational utility in this concept for our CSAR mission. Initial analysis has revealed the potential for significant operational advantage from the additional speed, manoeuvrability and range possible with the VTDP concept. Initial estimates indicate impressive cost effectiveness and affordability," says Gen Randall Bigum, USAF director of combat weapon systems.

The primary benefits of a compounded HH-60 would be a much faster transit time to the recovery area, and a greater range. A compound helicopter would be capable of speeds of around 230kt (425km/h) compared to 150ktfor a conventional machine, almost double the Pave Hawk's radius.

Under the USN ATD contract, Piasecki will fit an instrumented YSH-60F with a new tail boom incorporating a second generation ringtail, or VTDP, to provide anti-torque/yaw control and thrust vectoring.

The helicopter will also feature a composite lifting wing, modified drive system and flight controls.

An as yet unfunded element of the programme will add an auxiliary power unit to supplement the helicopter's installed power.

The USN is looking at VTDP for a number of applications such as bolstering the towing capability of the airborne mine countermeasures version of the CH-60, as well as extended maritime patrol and its own CSAR mission.

In addition to better performance and survivability, compounding offers to cut operational costs through reduced vibration and fatigue loads.

Source: Flight International