The right-hand inceptor controls ascent and descent.
Credit: Joby Aviation
Aviation
Week had the opportunity to sample the flight characteristics of the Joby air
taxi in a company demonstration simulator. I was guided through the remarkably
simple operation of the aircraft by Justin Paines, the chief test pilot for
Joby who, as a military test pilot, played a key role in developing the unified
flight control strategy for the Lockheed Martin F-35 Joint Strike Fighter.
My simulated
flight began at San Francisco International Airport (SFO). With propellers
stowed in up position, blades stationary and locked in the safe configuration,
there was plenty of headroom for my imaginary passengers as they boarded the
aircraft and settled into the four seats behind the pilot in the surprisingly
roomy cabin.
Although the
simulator is not the final version of the aircraft, it demonstrates the concept
of operations and generic layout of the cockpit. I moved a switch from “load”
to “taxi,” and the props began turning. There is no need to start the engines
with an electric aircraft—I just switched the vehicle on and confirmed
activation with a second switch.
·
See also: Joby Unveils eVTOL
Design Details And Certification Plans
The electric
motors provide instant power and, with a slight movement of the throttle-like
left-hand inceptor that controls longitudinal acceleration, all six propellers
angled slightly forward, and we began to taxi like a normal aircraft. Despite
the appearance of the inboard props in my peripheral vision as they pivoted
forward on either side, the all-round view remained excellent from the cockpit.
A short push
on the left inceptor to a soft detent started forward motion, and I let go once
we were underway. Meanwhile, a simple twist of the right-hand inceptor steered
the nosewheel. There is no need for rudder pedals or a separate nosewheel
steering control. We taxied to a clear area, and after clearance for takeoff
and preflight checks, I selected another switch that allowed me to “enable” or
“disable” flight.
A press on a
“confirm” button completed the two-step procedure, and we were ready for
flight. To take off, I simply pulled back on the right-hand inceptor and left
the left-hand inceptor alone, as I wanted to fly vertically upward without also
moving forward. Although at first it seemed strange not to be concerned about
adding power for vertical lift, the system automatically converted my command
for takeoff into the required motor torque. “We can go up like a champagne cork
and pull 2g vertically if we need to,” says Paine.
Letting go
of the right inceptor brought the aircraft to a gentle stop and, with my hands
off the controls, we entered a stable hover over the ramp. The integrated
flight and propulsion control system will maintain position in crosswinds. In
thrust-borne flight, aircraft control is through a combination of propeller
RPM, pitch and nacelle tilt.
Using the
twist grip, I yawed the aircraft around to face San Francisco and pushed the left
inceptor through the detent to begin transitioning to wing-borne flight as we
climbed to 2,000 ft. and accelerated toward the city. Speed quickly built up to
the cruise maximum of 175 kt. “The idea is the pilot can push the inceptor all
the way forward and they’re not going to break anything. It will just go to the
maximum permittable speed,” says Paines.
En route to
a rooftop landing pad, I was shown how to use an automated decelerate-to-hover
“shortcut” feature Joby is developing to give pilots even simpler control
options. With a press of the button—for the moment mounted on the right-hand
inceptor—the control system automatically deploys flaps and other effectors to
reconfigure from forward flight to a hover at whatever altitude the button is
pushed. In the simulator, the landing gear also extended automatically to
assist the deceleration. The aircraft initially will be certificated with fixed
gear, with the intent to introduce retraction later.
The
deceleration brings the vehicle from cruise speed to a complete stop in around
20 sec. with a comfortable braking force significantly less than the 0.4g load
sometimes imposed on airliner passengers by heavy braking during a landing
roll.
From the
hover, I then pressed the second “shortcut” button to accelerate to cruise. The
nacelles tilted to accelerate the aircraft to a predetermined speed. Joby is
still defining the speed options for this function, which reverses the
decelerate-to-hover sequence. It is also likely the buttons will be merged
into a rocker-type switch and relocated to the left-hand inceptor to fit better
with the intuitive feel of its acceleration function, rather than the
directional control function of the right-hand inceptor.
With the
city now closer, I set my sights on the landing pad. To aid the approach, a
blue line on the moving map display depicts the projected flightpath ahead of
the aircraft and uses airspeed to calculate where it will stop if the
“decel-to-hover” button is pressed at that moment. Pilots simply have to point
the aircraft so the blue line rests on the destination and, when the end of the
line touches the “H” of the helipad, a press of the button will bring them to a
stop over the pad.
In my
caution to make a safe approach, I pushed the button too early, which brought
us to a hover just in front of the pad rather than overhead. Decelerating to a
hover from wing-borne flight automatically blends the controls to the
transitional rate command mode used for precision hover tasks.
Pushing the
left inceptor forward, we edged in at just under 10 kt., and once over the pad,
I let go and we stopped in the hover. I then pushed forward on the right-hand
inceptor to descend, remembering the “push forward, houses get bigger; pull
backward, houses get smaller” mantra used by pilots learning to fly the
short-takeoff-and-vertical-landing F-35B using essentially the same aspect of
the unified control law.
With my
first vertical landing accomplished, I pulled back on the inceptor and lifted
off—while pushing the “accel-to-cruise” button. “You’re pointing where you want
to go, and the airplane does all the flying,” says Paines. Passing over the
downtown skyscrapers, I headed to Alcatraz Island, where I allowed the blue
line to guide me to another precision approach and landing by the old prison
walls.
The
simulator experience culminated with a conventional takeoff and landing at SFO.
From a standing start on the runway, I pushed the left inceptor through the
detent and rotated at 70 kt. Climbing quickly, I positioned for an approach.
Aiming for a touchdown point halfway down the field, I slowed until I was over
the runway threshold at just 26 kt. but with no concerns over directional
control or descent rate, as the nacelles pivoted to provide lift and thrust
until we gently touched down.
The
simulator experience showed that, just as in the F-35, developers have taken
away the concerns over flying the aircraft to enable the pilot to focus on the
mission. At no point had I become worried about piloting the aircraft or about
issues such as stall speed or, as a rotary-wing pilot, an overwhelming
workload.
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