Custom Planes 10/99
---BUILDING A BRITISH BERKUT--
Setting A Standard Of Excellence---
Text and Photos By Vicki Cruse

Page 2

What's a Berkut?

The Berkut is an evolution of Burt Rutan's Long-EZ, with some significant changes. The Berkut was designed by Dave Ronneberg, chief designer at Renaissance Composites in Santa Monica, California. The Long-EZ has fixed gear and a retractable nosegear and is built from plans, while the fullyretractablegear Berkut is constructed from a kit. The Long-EZ canopy is one piece, whereas the Berkut canopy consists of a canopy for each person, much like a fighter jet. The Berkut ailerons are 6 inches longer than on an EZ and have a slightly larger chord. The strakes (the triangle portions between the fuselage and wing) have a convex upper surface, instead of the flat surface found on the EZ.

Originally designed to be powered by an I0-360, the Berkut is capable of accommodating a 260-hp I0-540. Performance numbers for both configurations are nothing short of impressive. Powered by an I0-540, the Berkut has a cruise speed of 265 mph at 75 percent power, giving it a range of about 1000 miles. Fuel burn with the I0-540 is 16.2 gph in cruise, and the fuel capacity of the airplane is 58 U.S. gallons. Performance numbers for an I0-360 powered airplane are also impressive, as you are about to discover.

The Berkut makes use of carbon fiber and Kevlar in the design. Carbon fiber was chosen for its relative stiffness, compared to fiberglass. Contrary to popular belief, carbon fiber is not lighter than fiberglass. Volume-for-volume, carbon is only slightly lighter than fiberglass, but it is one and one-half times stronger and four times stiffer. The use of carbon fiber in the Berkut prevents unwanted flexing, particularly in the wing, making for a more rigid wing with no weight penalties. Kevlar is used in the belly, under the glass outer skin, to protect the underlying skin in the event of a gear-up landing.

(Left) Klaus Savier supplied the propeller. Waters fabricated and designed the rear spinner bulkhead.

The prototype Berkut was completed in the summer of 1991 and shown at Oshkosh. Orders were taken for kits at Oshkosh 1992, and deliveries began in January 1993. The first kit went to Glenn Waters in the United Kingdom.

Meet Glenn Waters

At Oshkosh 1992, Waters decided he wanted to build a Berkut. It fit the allowable envelope for homebuilts with the PFA: under 2000 pounds gross weight and less than 250 hp (with the 10-360). He then went to the PFA to obtain approval for the airplane. Since the Berkut evolved from a Rutan design familiar to the PFA, approval to purchase a kit was obtained. The first parts of the kit arrived in 1993, and the airplane was a project of five winters, although not five full years, since Waters' work schedule did not allow for building year-round.

Waters' background is not that of an ordinary builder. In the 1970s, Waters worked at Lotus on the Grand Prix racing team. The boss at Lotus was an avid aviator who commissioned Burt Rutan to build a small, two-place canard aircraft that Lotus was intending to manufacture and sell. This did not happen, but as a result, Waters became familiar with the Rutan designs-the VariEze and the Long-EZ-and started his wish list for a Rutan airplane. Twenty years later, he purchased a completed Long-EZ, which he owned until 1996. Waters is a private pilot with approximately 430 hours.

(Right) Glenn Waters looks proud after his first solo flight. Dave Ronneberg, the designed of the Berkut, looks on.

All of Waters' professional life has involved motor sports. He began at Lotus on Formula 11 cars and later, spent nine years associated with the Grand Prix team. He was also involved with Toyota, overseeing the Le Mans program and domestic motor sports at the Formula III level. He is still involved in the motor sports industry, but not as much as before.

With a background in motor sports, the jump to building an airplane was not a difficult one. Many construction techniques were similar, particularly working with composites. His involvement with motor sports also gave him numerous contacts for various components he wanted incorporated into the Berkut. The biggest challenge Waters faced while building the airplane was finding the composite materials necessary; it required purchasing the materials outside the United Kingdom.

When asked if he would ever build another Berkut, Waters said he would, but he would make the airplane a little less complicated. He said, "There's a bit too much froufrou in it." You will see exactly what he is talking about shortly. The best part of the project for him was satisfying the requirements of the PFA and seeing the airplane fly for the first time. Regarding the part he said he would miss least (sweeping all the dust that resulted from sanding the airplane) he said, "I'll bet I had nearly as much time sweeping as I did working on the airplane. "