By DAN JOHNSON
Now in its fourth generation, the Gen H4 took
its first flight at AirVenture'99 on Friday from the Ultralight Area airstrip
on the south end of Whitman Field. You may question the truth of this statement
when you see this curious little helicopter, but the proof is in the flying
and fly it did.
A design sure to puzzle many experienced pilots,
those willing to control their skepticism may realize the large amount
of work that went into the unique aircraft. With many unusual or rare aircraft
on display at AirVenture '99, the Gen H4 (named for designer Gennai Yanagisawa)
fits perfectly.
Power for the Gen H4 comes from four tiny
two-cylinder, two-stroke engines that produce a total of 40 horsepower.
Each engine only weighs a remarkable 6 1/4 pounds, which gives them a very
high power-to-weight ratio of 1.6 horsepower per pound. In fact, it was
this little engine that formed the basis for Yanagisawa's |
| ULTRA-LIGHT: The Gen H-4 looks like a cross between
a helicopter and a flying platform. |
|
company, Engineering System Company, Ltd. (ESCO) of Japan.
Each engine has its own electric starter and a clutch
that allows one engine to fail without interfering with the ability of
the others to keep on creating lift.
After working in the automobile field early
in his career, Yanagisawa later started his own business making high precision
automated assembly and inspecting machinery. After twenty years of success
in that field, Gennai turned his considerable engineering gifts to a helicopter
that can qualify under FAA’s Part 103 for ultralight vehicles.
In fact the Gen H-4 easily qualifies. With
an maximum empty weight limit of 254 pounds (excluding floats and safety
devices like emergency parachutes), the H-4 uses only 168 pounds of FAA’s
allotment. It is also within the speed range of Part 103 and has the appropriate
amount of fuel.
Two factory pilots operate the H-4 for development
and demonstrations. Neither man has a pilot's license and neither has any
experience flying rotary-winged aircraft. Yet Friday's two demonstration
flights showed the pilots possess good control over the machine.
Most aviators who know anything about helicopters
are aware that hovering flight is one of the most demanding skills, often
described as trying to stand at attention on a beach ball. Despite this
perception, H-4's pilot hovered in good control for several minutes.
The machine is operated with a control yoke
directly in front of the seated pilot. Configured much like the overhead
joystick made famous by the Benson Gyrocopter, the pilot moves the yoke
fore and aft for speed control and from side to side for lateral movement.
The entire rotor head moves similarly to gyro control systems but goes
one step further by also have all four engines move as well, greatly simplifying
the operation.
Since the H-4 uses counter rotating rotor
blades, no tail rotor is needed. Yaw is controlled electronically via a
button the pilot pushes. Other switches are also arranged on the control
yoke and the pilot has minimal instruments to monitor the engine performance.
In the event of a single engine failure, the
remaining three engines can sustain flight, says ESCO. Even if two engines
fail, the company reports the Gen H4 can be safely landed. In the very
unlikely event that all four engines fail (perhaps by fuel contamination),
the aircraft can not autorotate to a landing like a conventional helicopter
as the rotor blades have a fixed pitch position.
However, should the unlikely become reality,
ESCO has taken steps to install a ballistically deployed parachute. Mounted
in a disc-shaped pod above the rotor blades, a 'chute equipped H-4 can
save its pilot with swift deployment by rocket motor. To date, the system
has not been installed nor tested.
Rotorcraft are not the cheapest aircraft you
can buy on Wittman Field and the Gen H-4 is no exception. You'll have to
part with more than $25,000 to have one of the ultralight helicopter's
in your garage.
Seen up close, the workmanship may justify the price with beautifully
machining and clever engineering. And compared to otherrotary-winged choices
potential buyers have, the H4 is modestly priced.
Gen H-4 isn't available for purchase yet as
more flight development is planned after the parachute is fitted. However,
it proved to be a huge crowd pleaser during demonstrations and you might
want to see it for yourself. |
©1999, Northwest Flyer, Inc.
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