A US company has signed an agreement to commercialise a NASA-developed tailboom modification that improves helicopter stability and reduces tailrotor power requirements.
Everett, Washington-based Boundary Layer Research (BLR) plans to certificate the modification - upper and lower strakes running the length of the tailboom on one side only - on the Agusta A109, Bell 206, 212 and 412, Eurocopter AS365 and Sikorsky S-76 over the coming year.
BLR has signed an agreement with Hurst, Texas-based Global Helicopter Technologies to certificate the strakes on most of the Bell line. Another similar agreement is pending with a company that will provide certification assistance on Eurocopter designs.
The Bell UH-1 is the first helicopter to be fitted with the strakes, which interact with the main-rotor wake to generate an anti-torque sideforce on the tailboom. A US Army example was used to flight test the strakes. Under direct agreements with NASA, the New Zealand and Australian armed forces are equipping their UH-1s with tailboom strakes.
BLR, meanwhile, has supplied a set of strakes to the US Army for flight tests planned for March as part of a UH-1 upgrade effort. The UH-1 modification costs $10,000, increases service ceiling by 4,000-6,000ft (1,200-1,800m) and, says BLR, reduces the amplitude and frequency of tailrotor pedal inputs by 50%, reducing fatigue.
Source: Flight International
