Berkut aircraft

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Berkut aircraft are tandem-seating two-seat homebuilt canard aircraft that are built primarily of carbon fiber and fiberglass.

The prototype Berkut aircraft was designed and built by Dave Ronneberg and Kerry Beresford as part of a business partnership called Experimental Aviation between Ronneberg and Donald Murphy [1] between 1989 and 1992. The name was taken from the book by Joseph Heywood [2]. In 1992 their partnership dissolved, and Ronneberg (incorportating as Experimental Aviation, Inc.) brought the aircraft to market as a kit while Murphy wanted to shelve the project entirely. A series of lawsuits between the two resulted in bankruptcy for Ronneberg and Murphy as individuals, and for EAI as a corporation. The kit was resurrected by Renaissance Composites, under Richard Riley in 1996, with Ronneberg working as a consultant. In January 2001, under pressure from Ronneberg, Renaissance sold the business to [3] Berkut Engineering Inc., owned by [4] Vicki Cruse. That company withdrew the aircraft from the market in 2002. Ronneberg continues with the project, which is now directed at UAV (Unmanned Aerial Vehicle) markets [5]. In 2003 a deal was struck to sell the project to [6] Republic Aerospace, but it was not consummated. Cruse is no longer involved with day-to-day operations, but maintains ownership.

The Berkut is descended from the Rutan Long-EZ, with the primary differences being retractable main landing gear, dual canopies, and molded fuselage, strakes, and spar. Aerodynamically only minor changes were made. The fuselage was stretched, and the nose, canard, instrument panel and plot moved forward one foot, to allow a heavier engine to be used in the back. The main wing trailing edge was straightened, removing a small bend in the trailing edge of the Long EZ wing. The lower winglet was removed and the aileron size increased in both chord and span, increasing roll rate. Early Berkuts used wings and canard that were structurally similar to the Long-EZ and using a solid Styrofoam core, but used with carbon fiber skins instead of fiberglass. The fuselage and winglets remained fiberglass. Later versions (kits produced after spring 2000) used fully-molded carbon fiber canards and wings, leaving only minor fairings and tip surfaces to be carved from foam. The Berkut has always used the Roncz canard airfoil, which is more tolerant of bug and rain contamination than the original GAU airfoil used on the Long-EZ.

Berkuts used a retractable main (rear) landing gear system designed by Shirl Dickey for his E-Racer homebuilt. Originally Berkut used gear parts produced by Dickey, but over time they were repeatedly re-engineered and strengthened. Later kits had gear components produced entirely in-house. Like the earlier Vari-Eze and Long EZ, the Berkut parks with its nose gear retracted to prevent the plane from tipping over backwards when parked without a pilot in the front seat. Some early Berkuts utilized hydraulic nose-gear extension systems, but most have used an electro-mechanical jack-screw. With the electric system the pilot can climb into the cockpit with the nose down, then extend the nose gear, raising the airplane with him inside.

While the Long-EZ was originally designed for the Lycoming O-235 108-118 hp engine, the Berkut was designed from the outset for the larger Lycoming IO-360 180 hp engine. The aircraft was later adapted (with a different engine mount, cowls and battery location) to accept the 260 hp Lycoming IO-540, which most builders chose. With the 540, some have reportedly reached speeds of 300 mph in level flight.

A flight test of the aircraft, and photographs, can be found here: http://www.airbum.com/pireps/PirepBerkut.html

James Redmon, who built Berkut serial number 013 (N97TX), maintains a web page documenting his experience building and flying the plane http://www.berkut13.com/berkut.htm

Specifications

FULL THROTTLE, 6,000' MSL 247/275 MPH TRUE 13 /19.5 GPH

STANDARD CRUISE SPEED8,000' MSL, 75% POWER 239/260 MPH TRUE 10.3/16.2 GPH1256/852 MILE RANGE (30 MIN RESERVE)

ECONOMY CRUISE8,000' MSL 215 MPH TRUE 7.7 GPH 1512 MILE RANGE (30 MIN RESERVE)

VNE (NEVER EXCEED SPEED) 350 MPH

VA (MANEUVERING SPEED) 230 MPH

VLE (LANDING GEAR EXTEND) 200 MPH

RATE OF CLIMB 2000/3000 FPM (SEA LEVEL)

MINIMUM CONTROLLABLE AIRSPEED 65 MPH

WINGSPAN 26' 8"

HEIGHT 7'6" (PARKED, GROUND TO WINGLET TIP)

LENGTH 18' 6"

SEATS 2, TANDEM

LANDING GEAR TRICYCLE, RETRACT

FLAPS NONE

ENGINE LYCOMING IO-360 OR IO-540 WITH ELECTRONIC IGNITION

HORSEPOWER 180/260 MCP AT 2750 RPM

POWER LOADING 11.1 / 7.7 LBS / HP

WING AREA 110 SQUARE FT.

WING LOADING 18.1 LBS / SQUARE FT.

GLIDE RATIO (L/D) 18 / 1

PROPELLER COMPOSITE 67" DIAMETER, 91/103" PITCH (LIGHT SPEED ENGINEERING)

PROTOTYPE EMPTY WEIGHT 1035 / 1150 LB.

GROSS WEIGHT 2000/2100 LB.

USEFUL LOAD 965 LB. FUEL CAPACITY 58 U.S. GALLONS

DEMONSTRATED CROSS WIND COMPONENT 25 KTS

MIN. LANDING / TAKEOFF RUNWAY REQUIRED 1100 FEET

[edit] See also

• Rutan Long-EZ
• Rutan VariEze
• Rutan Defiant
• Steve Wright Stagger-Ez
• Cozy MK IV
• Velocity SE
• Velocity XL
• Canard