Aft Body Strakes

The modification consists of two tapered strakes which are approximately 5 ½ feet long that are riveted to the underside of the aft section of the fuselage. Because the rear most portion of the strakes is actually attached to the tail cone the strakes incorporate a split design which allows the tail cone and aft section of the strakes to be removed as one piece for maintenance. Installed, the kit weighs in at 7 ½ lbs.

The strakes are designed to improve the directional stability of the Duke, reduce aft body drag, and reduce Dutch roll oscillations. The reduction in Dutch roll is most apparent to the passengers riding in the back of the airplane and is the main reason the strakes were developed. Boundary Layer Research test pilot Bob Desroche said that the aft body strakes "improve the ride comfort at cruise speeds, and provide a more solid feel at low speed". He also states that "the company tests indicated a Vmc reduction of two knots" although BLR did not take credit for the reduction at certification.

The strakes are available in kit form with all the necessary parts, installation instructions and certifying paperwork included. The kit can be installed by any qualified maintenance facility. Installation time is approximately 16 hours plus paint. There are no placards added or airspeed indicator dial changes required with the kit.

Boundary Layer Research, Inc., 3125 100th St. SW Hangar C75-5, Everett, WA 98204. Tel: 425-353-6591; Fax: 425-355-3046.