Berkut Under the Microscope
When Waters first approached the PFA with the proposal to build a Berkut, he was given the initial approval to purchase the kit, because the PFA had quite a history with Long-EZs and was familiar with the basic design of canard aircraft. However, since the Berkut was the first of its kind in the United Kingdom, approval of the design was still required before a permit to fly could be issued. A permit to fly is similar to our airworthiness certificate and operating limitations, combined.
At
the time Waters decided to build a Berkut, the prototype had flown about
one year and had approximately 200 hours on it. If the design had had
2000 total hours, the PFA would have approved the design by examining
the kit and relying on the in-service time on the fleet, noting any problems
or trends within the design-particularly strength and aerodynamic characteristics.
The responsibility of meeting the requests of the PEA engineers lies with
the builder, not the kit manufacturer, although cooperation with the kit
manufacturer is absolutely necessary to meet the requirements set forth
by the PFA.
(Above right) The right side of the cockpit has the side-mounted stick. Waters installed vertical mounted flight instruments.
When Waters started his Berkut, John Tempest, the deputy chief engineer of the PFA, began a comprehensive study of the design compared to the Long-EZ. A set of plans, a video, magazine articles and any other information available on the Berkut was provided to the PFA. It then determined there were a few areas of significant difference between the Berkut and the Long-EZ and commissioned a study of the Berkut in these areas. Structural analysis of the landing gear, strake and midsection spar was required. One PFA request required Renaissance Composites to videotape several heavy landings (minimum 3G) of a Berkut to determine how much the gear flexed and if anything in the gear bay moved.
In addition, the PFA required a headrest be placed behind the pilot's head, along with additional warning lights and placards. If the structural analysis or any other requested study of the airplane had not met the standards established by the PFA, Waters would have had to modify the airplane until the PFA was satisfied with the results. Future Berkut builders in the United Kingdom must meet these design standards, most of which were determined through the efforts of Waters. Any proposed changes from these standards by a future builder must be approved by the PFA.
During the building process, Waters had to hire a PFA-approved inspector to document workmanship of the airplane. Since this was the first Berkut, Waters was issued a Project Build Book for a Long-EZ, the closest set of standards held by the PFA for a canard airplane. This book contained 34 different inspections that had to be signed off by an inspector. For instance, when a structure is ready to be closed, it must be inspected. The inspector assigned to Waters' airplane, Graham Singleton, a Long- owner, had to make sure each part of the airplane conformed to the drawings of the airplane and that the construction standard was such that the airplane was structurally sound.
A Formula One Berkut
Often, photos do not do an airplane justice, and this is the case with Water's Berkut. The biggest disappointment regarding this Berkut is that it is not likely the airplane will ever touch down on U.S. soil to be appreciated for its workmanship and attention to detail. This airplane is one at which to marvel.
Prior
to the arrival of Dave Ronneberg, Waters had run the engine on the ground
and completed a high-speed taxi. Over the past five years, Waters had
been in contact with Ronneberg, discussing the airplane and PFA requests
for additional information. When asked what his expectations were prior
to actually seeing this Berkut, Ronneburg said, "I expected a Formula
One race car, and that's exactly what I got."
(Left) The left side of the cockpit has the power console plus a data-logging display usually found in race cars.
Once Ronneberg arrived and picked his jaw off the hangar floor, he checked the airplane thoroughly and was briefed on the systems and avionics in the airplane. The aircraft was pushed outside for an engine runup to check for leaks and avionics function. No leaks or problems were found, and the airplane was cowled for its maiden flight the next day.
Prior to the first flight, Ronneberg was hoping the airplane would fly as well as it looked, but he also knew this is not often the case. With Ronneberg at the controls, Waters watched his airplane take flight on a rare sunny day. According to Ronneberg, after the first flight, " ... the airplane flew with the ball perfectly centered, the roll feel was exactly the same to the right and left, with no slop in the ailerons, and the canard was built perfectly, with no flat spot in the elevator travel."
Upon its return, the aircraft was uncowled to check for engine leaks and vibration damage to the cowl- All aircraft systems functioned perfectly. There was a spot on the upper cowling (caused by rubbing of an exhaust stack) that was found, and a stiffer spring was needed on the elevator trim. Both issues were resolved, and two more flights were conducted.
One
of the most interesting and useful pieces of equipment in this aircraft
is a data logging and display system, manufactured by a British firm called
PI Research Ltd. It is usually found in race cars. Waters has the instrument
set up to monitor 12 different components, including airspeed, rpm, altitude,
oil pressure and manifold pressure, to name a few. An on-board computer
records the data, which is downloaded onto a laptop computer upon the
completion of the flight. The download takes only a minute, and the entire
flight is graphically represented on the screen and can be printed out
later. This is the ultimate in trend analysis and data acquisition from
the flight. Every component can be analyzed and compared. As a side note,
the test pilot doesn't need to record any flight data, because everything
is recorded by the instrument. Hangar-flying tall tales, such as, "Oh,
yeah. I flew her 12 Gs yesterday," are completely eliminated with
this device in the airplane.
(Right) We are looking up into the wheelwell in the fuselage and wing. The retractable landing gear and wiring can be seen clearly, as can the rugged construction.
Waters did not vary from the basic Berkut design, but he made a few modifications, such as a fuel bladder as a fuel sump, low-friction bearings in the control system and a centerline duct to provide ram air to the engine. He also moved the landing light to the nose. Waters' attention to detail included a fuel selector that prevented a cover from being closed and also impinged on the aft limits of the mixture and throttle controls when the fuel selector was in the "off' position. Along with this was a retractable step for use when the nosegear is not retracted on the ground. He also used Raychem on all the wiring in the airplane. This is another item borrowed from the auto racing industry. It looks like heat-shrink material for wires and encapsulates the wire within another layer of insulation, protecting them from water and abrasion. It is used in race cars to assist with preventing an ignition source for fire.
He also installed ball-and-socket canopy latches normally used to hold the nose assemblies on a Formula One race car that made them easily removable for inspections. The PFA required a latch for the front canopy that allowed it to be opened from the outside. For this, Waters designed a flush latch made of 17 moving parts that functioned perfectly with the latch he used inside the cockpit. His goal was to keep the airplane as clean as possible. The performance specs recorded during the test flights show exactly that.