Hands On: Flying the Joby Simulator

 - December 2, 2021, 12:59 PM
AIN editor-in-chief Matt Thurber trying out the fly-by-wire flight controls in Joby's eVTOL simulator.

Much of what Joby Aviation does is secret, hidden in a valley surrounded by steep mountains near Santa Cruz, California. But, especially in the wake of the company's recent New York Stock Exchange flotation, more details about Joby’s electric vertical takeoff and landing (eVTOL) aircraft are being revealed, and the company has been sharing more videos of the aircraft flying, including demonstrations of its amazingly low noise levels.

In fact, according to Joby—whose founder, JoeBen Bevirt, has been at this since 2009—FAA certification of its four-passenger aircraft is well underway and on track for 2023, which would be five years after Joby applied for type certification. The first pre-production prototype Joby aircraft is flying while a second test aircraft should fly soon, if it hasn’t already. Joby has locked down the certification basis for its aircraft, and it will be certified under the regulatory framework in Part 23 of the FAA regulations.

To introduce the Joby eVTOL to various stakeholders and those who can help spread the word, Joby has designed its own fixed-based flight simulator, one of which is at its Washington, D.C. government affairs office. I was recently invited to fly the simulator, and it was a fascinating experience because it highlighted a sea change in the way pilots will operate aerial vehicles in the future.

Joby has no short-term plans to offer an autonomous (non-piloted) aircraft, although that may come later. Its current design will carry four passengers and be flown by a qualified commercial pilot, and the company will operate its aircraft under the Part 135 regulations governing commercial aircraft operations.

Distributed Propulsion

The simulator is built to look like the cockpit of the real Joby aircraft, and it uses X-Plane simulation software for visualization and terrain display, but the flight modeling is all Joby-developed. Granted, anyone can design a wild-looking aircraft using desktop simulators, but my experience showed me that Joby’s engineers are serious about replicating the complex distributed propulsion machine that the company has designed. 

The advantage of electric propulsion is that instead of having one or two propellers driven by large combustion engines, multiple smaller electric motors driving smaller propellers can be placed at optimum locations all over the airframe. Each motor has just one critical part, a bearing, plus the propeller. These electric propulsion units (EPUs) provide power exactly where and when it is needed, giving designers extraordinary latitude to create aircraft that can fly in ways that many of us never imagined. 

Joby
Joby's eVTOL aircraft is on track for FAA certification in 2023. (Photo: Joby)

In Joby’s case, there are six propellers that can articulate to provide vertical or horizontal thrust or a combination of both. Each propeller is driven by two electric motors, for redundancy. If one motor fails, the other can easily take up the slack. Each motor is connected to a different battery pack, eliminating a single point of failure for that propeller. All of the propellers tilt, which is somewhat like a tiltrotor but far less complicated because there is no big turbine engine with hundreds of parts getting fed by copious gallons of fuel and being rotated by hydraulic pressure created by yet more moving parts attached to each engine. 

A tiltrotor aircraft like the Bell-Boeing V-22 or Leonardo AW609 requires great skill to fly because it combines helicopter and fixed-wing attributes. Helicopters by themselves also demand that pilots have a lot of training and skill, not to mention constant practice and recurrent training to stay sharp. 

All this is to underscore how different it is to fly the Joby aircraft. I have not flown a real tiltrotor, but I have flown helicopters, and the Joby is far simpler. When flying it, you don’t notice the transition between vertical and horizontal flight because it is all part of the design of the pilot-machine interface and also benefits from the way electric propulsion works.

For someone like me who doesn’t design aircraft, it would seem that a goal for a piloted eVTOL aircraft would be precision control made easy; you need to be able to make it do what you want, when you want, and fly exactly where you want. The more it can do this without forcing the pilot to have to think about how to manipulate a complex set of controls in precise little movements (I’m thinking helicopter here), the more it will succeed at its mission. 

By this, I don’t just mean flying passengers from A to B, but a higher-order mission: freeing pilots’ overworked minds from the complexities of controlling the trajectory so they can spend more valuable brain cycles on the critical aspects of flying. That means selecting the appropriate trajectory but with simplified controls; navigating safely and avoiding flying into thunderstorms, other aircraft, buildings, or mountains; and communicating as needed with air traffic control and in this new and modern age, ground-based assistants.

How Joby Flies 

Based on my experience in the simulator, I believe the Joby more than meets the above requirements. I’m going to assume the real aircraft flies similarly, and I hope to learn more about that eventually.

The cockpit features two displays, which are Garmin G3000 avionics, plus a single Garmin touchscreen controller for entering information, creating flight plans, and managing systems. The primary display has conventional airspeed, altitude, attitude, and vertical speed indicators as well as a flightpath marker. The main systems page shows a graphic of the six EPUs, with a bar graph for each indicating the torque that is being applied. This bar turns red if too much torque is being demanded, but the system prevents the pilot from applying too much power to any of the EPUs for too long.

Joby display
The flight and systems display on the Joby aircraft's Garmin G3000 avionics. (Photo: Matt Thurber/AIN)

The pilot has two controls, one for each hand, and no pedals. The left control is the speed control: move it forward to speed up, backward to slow down. This seems to be a more intuitive way to design a throttle/power lever. The righthand control is an inceptor or sidestick, and it controls three axes, pitch, bank, and yaw, but it also enables a function that is new to most pilots but that makes sense for an eVTOL aircraft: up and down. 

Like all eVTOLs, the Joby features a flight control system that is fly-by-wire, and this is pretty much the only way possible to control a distributed-propulsion aircraft effectively and safely. The beauty of fly-by-wire is that it gives designers even more control over how the aircraft feels to the pilot and lets the pilot make it act in a stable manner, even when the control system is essentially corralling a wildly unstable vehicle. I’m not saying the Joby is unstable, but it would probably be impossible to make it act in a stable manner controllable by a pilot with conventional cable and pushrod controls at an efficient weight. This is inherent with many fly-by-wire aircraft, such as the F-16 fighter, F117 Nighthawk, F35A, and others and is nothing new to flight control system engineers.

With just a short briefing on how the controls work, I was almost immediately making the Joby do exactly what I wanted. The pilot-machine interface is beautifully designed and implemented. I have never felt so in control of an aircraft and so free to focus on flying tasks rather than on constant control manipulation. 

To get into a hover, all I had to do was pull the inceptor back with my right hand, and the Joby climbed smoothly a few feet; then I let the control spring back to center and the aircraft simply hovered in place.

This was like flying a fictional, imaginary perfect aircraft; I can’t think of any other way to describe it. At first I had no idea what was going on outside, although if I were flying the real Joby I would have been able to look outside and see the propellers spinning and some of them translating forward and backward. But there is also the information about the state of the propellers on the display, with indicators for rpm, torque, and tilt for each EPU, and that helped give me some perspective, although ultimately, if the aircraft moved exactly the way I wanted, do I really care how it got there? This is an interesting philosophical question, and the answer is that some pilots will be geeked enough to want to know a lot of detail about how the aircraft works and others will be happy just to fly it—the same as any group of pilots.

TRC Mode

For takeoff and landing, the Joby goes into “translative rate control” (TRC) mode, which limits speed to seven to eight knots to make it easier to have precise control when you're close to the ground. That speed has been increased in newer versions of the flight control software. I tried a turn, again using the righthand inceptor control, but I managed to twist and yaw at first, instead of moving the control to the left or right to induce a bank. I found that relaxing my grip on the control helped; all you need is two fingers to push the control, and this helps avoid unconscious twisting. I did some banks, then practiced yawing while level, and the Joby responded perfectly, allowing me to point the nose at various Washington, D.C. landmarks.

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Flying the Joby eVTOL simulator at Reagan Washington National Airport.

I had taken off from simulated Reagan Washington National Airport (DCA) and was flying near the Pentagon, which is kind of discombobulating because as much as eVTOL developers want to offer their services to busy metropolitan areas all over the world, some cities like Washington just aren’t going to cooperate. The 9/11 attacks so upset the powerful elite that they banned small aircraft from DCA, unless they are flying military missions or for a government entity like the police or first responders. That is unlikely to change just because eVTOLS are cool, quiet, and electric.

Once out of TRC mode, I yawed around so the Joby faced the end of a runway at DCA, then pulled the inceptor back to raise the nose and pushed the lefthand speed control to gain speed. I kept the speed at around 70 knots and the nose pointed up and continued climbing to about 600 feet, then leveled off. 

I played with the controls to get a feel for how Joby's as-yet-unnamed aircraft responded. I liked how the speed control worked. It felt natural and intuitive. The inceptor, however, left me with some questions. 

In wing flying mode (propellers forward), pulling back on the inceptor induces a change in the nose position, raising it above the horizon, but limited to a certain amount. Once set to a different pitch attitude, letting go of the inceptor leaves the nose in that attitude. This is similar to a flightpath-stable fly-by-wire system, as seen in Airbus, Embraer, and Falcon designs. You move the stick to set a flightpath up or down or level, then let go and the airplane stays right in that attitude (it’s really a flightpath). 

But oddly, in the Joby, when you bank left or right, it steepens to a maximum of 30 degrees, but when you let go of the inceptor, the bank angle goes back to zero or wings level. For a pilot raised on regular flight controls and with some fly-by-wire experience, this seems strange, but it ended up working once I wrapped my head around it. (In the flightpath-stable airplane designs, in a banked turn, the airplane remains banked when you let go of the sidestick controller.)

I have to imagine that a ton of activity is going on with the computers and the motor controllers and fly-by-wire system to make everything integrate so smoothly, and for the pilot, that is the result: smooth banks, smooth pitch changes, smooth yawing motion with no wing dipping. 

Climbing to 1,100 feet, I followed the Potomac River to Rosslyn, then I descended and circled the aircraft around the Pentagon and aimed for a landing at the military facility’s helipad.

Slowing to a hover, which happens faster by pointing the nose up a little while pulling the speed control backward, I brought the Joby to a standstill a few dozen feet above the ground. I then tried flying backward, which just requires pulling the speed lever back for “negative” airspeed. Maximum speed going backward is about 20 knots.

Pushing the speed control forward slowed the aircraft to zero and put it back into a hover. In this configuration, I then was able to descend straight down by pushing the righthand inceptor forward. This illustrated the difference between vertical mode and wing mode: when the propellers are all pointed straight up, moving the inceptor forward or backward causes the aircraft to go straight down or up. But when the propellers are pointed forward, moving the inceptor changes the nose position, which should make the aircraft follow the nose and descend or climb.

Precision Control

Approaching the helipad, I went back into TRC, and this is where the precise control proved its mettle. All I had to do was fly near the helipad and inch my way gradually over until I was positioned exactly above the center with the nose pointed where I wanted it using the yaw control. Then I just pushed the inceptor forward and lowered the aircraft straight down for a gentle touchdown. Simple and sweet, almost nothing to it.

The Joby can also be flown on a runway for a wing takeoff or landing, with the propellers pointed forward. Landing safely after a propeller or EPU failure can be done vertically or horizontally. 

Although this was just a simulation of the Joby aircraft, I was impressed with how easy it is to fly. Within minutes, I felt comfortable and in full control. The aircraft did exactly what I wanted, though obviously with some limitations. I didn’t have to think about how to configure the propellers to get it to do what I needed. I’m eager to dig deeper into the Joby technology and see how pilots will be trained to fly this aircraft. 

If this is the future of piloting, I’m all for it. We all know that there is a limited segment of the population capable of becoming safe pilots in conventional aircraft, and traditional flying requires a huge amount of initial and ongoing proficiency training. In traditional aircraft, whether fixed-wing or rotary-wing, pilots can easily get themselves in trouble because they have to focus so much on control manipulation along with other critical tasks. Eliminating the massive effort needed for control manipulation and allowing pilots to focus on higher-order tasks is a significant accomplishment and one that will likely improve the flying environment and bring giant leaps in safety.

This story is from FutureFlight.aero, a news and information resource developed by AIN to provide objective, independent coverage and analysis of cutting-edge aviation technology, including electric aircraft developments and advanced air mobility.