In our continuing overview of artificial stabilization systems for RC, I wanted to test one of the newest systems on the market. WISE is a stabilization system recently released by Hobbico. Although the WISE module is a discrete unit, it is currently only available imbedded with Flyzone’s flagship trainer, the Sensei FS.
WISE (no, it’s not an acronym) is meant to be a training aid for pilots learning to fly fixed-wing aircraft (as opposed to rotary-wing helicopters & multi-rotors). Like other stabilization systems, it uses accelerometers and gyros to sense what the model is doing. Using this data, the system can bring a wayward model back to level flight. It also damps overly-exuberant control inputs from the pilot to avoid getting the model into a bad attitude in the first place.
The WISE module is factory-installed to a tray in the fuselage of the Sensei FS. It is connected between the radio receiver and flight control servos.
The Sensei FS
Flyzone’s Sensei is a popular trainer model that has been around for a few years. With a 58″ wingspan, it is a sizable airplane with Cessna-like looks. Other than the addition of the WISE system, little else seems to have changed in the new FS (Flight Stabilization) version. The airframe is made of molded foam components and it features a brushless power system.
The Sensei FS can be purchased as a Receiver-Ready (Rx-R) or Ready-to-Fly (RTF) kit. Both versions are mostly factory-built with servos installed for each control surface and the motor/ESC and WISE module already in place. The primary difference is that the Rx-R model allows you to install a 6+-channel radio system of your choice. Going RTF gets you a Tactic TTX610 radio system with a TR624 receiver. The RTF also adds a 3S-2100mAh LiPo battery and a simple AC/DC charger. Hobbico provided an RTF kit for this review.
Before getting to the specifics of the WISE system, let’s talk a little about the Sensei FS. The quality of the kit is very consistent with others wearing the Flyzone badge. The foam parts are cleanly molded and the components fit together well. Assembly is a nuts-and-bolts operation, so no glue is required.
The RTF Sensei FS includes a 3S-2100mAh LiPo that provides about 10 minutes of flight time.
While neither is a deal-breaker, there are a couple of things that I do not like about the design of the Sensei. First of all, the motor cowling is glued into place. This means that any motor repair work, such a replacing a bent motor shaft, will require hacking up the foam and installing a replacement cowling.
Secondly, access to the battery is somewhat restricted. A small plastic hatch provides an opening to the battery bay. The hatch isn’t much bigger than the battery’s girth and the bay is oversized, allowing the battery to flop around if not secured. The manual does not mention how to secure the battery within the bay. Presumably that is the job of the patch of Velcro installed on a side wall, and the reason that spare self-adhesive Velcro is provided as well (to be placed on the battery).
Here you see the small access hole for the battery compartment. Once the battery is in place, I insert the wedge, stuff in the wires, and replace the hatch.
I just couldn’t see poking my fingers through the small hatch to pry the Velcro loose for every battery change. Instead, I made a wedge from a hacked up pool noodle (any squishy foam will do). I glued a small length of craft stick into the wedge as a handle. To keep both components from getting lost too easily, I tethered the wedge to the hatch with a few inches of string.
To install the battery, I insert it through the hatch opening, connect the power plugs, insert the wedge to keep the battery in place, stuff the wires inside, and replace the hatch.
I created this soft foam wedge to hold the battery in position. It is tethered to the access hatch to keep both from getting lost during battery changes.
The TR624 receiver was already installed in the airplane with all servo and WISE connections made. I just had to verify that the control surfaces moved in the correct directions and the WISE module responded appropriately. This all checked out fine. However, during this process I noticed that the setscrews which lock the elevator and rudder pushrods to their respective servo arms were not adequately tightened. I tightened these very important screws after adding a drop of thread locker to each.
The WISE module measures roughly 1.5″ x 1.0″ x 0.5″. It is rigidly mounted to a plywood tray beneath the wing saddle. Electronically speaking, the module is located between the radio receiver and the control surface servos (aileron, elevator, & rudder). Another connection to channel 6 of the receiver allows the pilot to select between three stabilization modes.
Beginner mode limits to maximum pitch and roll angles to about 30-degrees. The idea is to provide a narrow window of flight attitudes so that a beginning pilot does not get too far out of sorts. If the pilot gets disoriented or flustered he/she can simply let go of the right control stick. This will make the Sensei immediately return to straight and level flight.
Intermediate mode behaves much like beginner mode, but the angle limits are upped to 90-degrees. That change is sufficient to let a new pilot experiment with aggressive maneuvering, while not being completely off the leash or giving up the safety net of auto- leveling when the control stick is released.
The WISE website suggests that switching to advanced mode effectively disables the stabilization effects of the system. However, my bench and flight testing reveal that the system is still doing a little something. When the model rapidly deviates from its current orientation (even if not straight and level) in advanced mode, the relevant control surface(s) briefly move to counteract the deviation. In this way, WISE appears to respond like AS3X to damp the effects of wind and turbulent air on the flight path of the model.
In addition to the 3-position mode switch on the transmitter, there is also a momentary “bailout” switch. Regardless of the mode you are in at the time, engaging this switch overrides any flight surface control inputs and brings the airplane to level flight.
The switch being actuated here is the bailout switch. It will quickly bring the Sensei to straight and level flight from any orientation.
The TTX610 also has a 2-position switch for dual rates. This one switch simultaneously controls the rates for pitch, roll, and yaw. High-rate is 100% servo throw while low-rate is fixed at 60% throw. Using the rate switch in conjunction with the stabilization modes provides six levels of responsiveness. Low-rate/beginner mode is the most sedate, while high-rate/advanced mode would provide the most maneuverability. Stepping up through that progression of responsiveness would be a good ladder for new pilots to climb.
There does not appear to be any provision for adjusting the parameters of WISE. A diagram in the Sensei manual shows gain adjustment pots on the WISE module, but my example has none. That may be a limitation for implementing WISE in other airframes, but (spoiler alert!) the stock settings work very well in the Sensei FS.
Flying with WISE
To test the flight performance of the Sensei FS, I started flying it with low-rate/beginner mode settings and worked my way up through the control options. Overall, I think that the system does what it is intended for. One of the most common mistakes of new pilots is to input overly large commands on the sticks. I emulated this behavior to see how the Sensei would react. With the limits imposed by the gyro, I couldn’t get the plane into an uncontrollable, crash-imminent situation. At the same time, the controls weren’t so sedate that I ever felt disconnected from the model. The airplane did what I told it to do. It just did so within a narrow and well-defined performance envelope.
The WISE system tailors the flying traits of the Sensei to make it easier for beginners to handle. It is still beneficial to have an instructor show you the ropes of RC.
Moving into the intermediate mode, there is definitely more freedom given to the pilot. A 90-degree bank or pitch angle gives a rookie plenty of rope to hang themselves if they don’t have the presence of mind to hit the bailout switch when necessary. For pilots who are ready for this freedom, intermediate mode can provide a new level of flying excitement without getting too far beyond their comfort zone.
The airplane has enough power and control authority to perform basic aerobatics, albeit slowly.
In advanced mode, there are no pitch and roll limits. I was able to do basic aerobatics such as loops, rolls and inverted flight. The airplane has enough power and control authority to perform these maneuvers, albeit slowly. To test the bailout switch, I engaged it several times when I felt like the airplane was in the worst possible attitude (inverted, pointing straight up, pointing straight down, etc.) Each time, the Sensei was back to normal flying within a second or two. Even with the high-power horsing around that I inevitably do, I can get 10 minutes flights with the stock battery.
One of the features of WISE is that it inputs slight up-elevator control when the throttle is above half power. The point is to make takeoffs simpler. To test this, I lined up the Sensei on the end of the runway, set the switch to beginner mode, applied ¾ power, and took my hands off of the controls. The model rolled forward and lifted off into a gentle climb. Without any input by me, it stayed on this trajectory until I had to turn the model to keep it in sight.
I was very surprised by how well the Sensei FS glides. The first few times I tried to land it, I began with a normal approach to the runway. Even though I had completely chopped the throttle, the model just kept on flying without losing much altitude. It still catches me off guard sometimes. I let one of my buddies try the Sensei and the same thing happened to him. This bird is a floater.
The lightweight Sensei glides exceptionally well, yet it tolerates considerable wind with the WISE system aboard.
Models that glide well (light wing loading) are often easily upset by the wind. I took the Sensei FS out on a day with a stiff wind blowing directly across the runway. The WISE stabilizer did a good job of keeping the model from bouncing around in the rough conditions…even in advanced mode. When flying crosswind, the gyro seemed to counteract the model’s natural tendency to weathervane into the wind. The result was that the Sensei crabbed forward at an angle, while still staying on a path over the runway. I felt like the model was considerably easier to fly in those conditions than a non-stabilized model with similar wing loading would have been.
The TTX610 is an analog radio, so it can only be used for one model and its adjustment options are fairly limited. Don’t dismiss the radio as a throwaway–it works just fine. In fact, its simplicity may be comforting to a new pilot who already has plenty to think about.
In my case, I want to be able to use the same radio for multiple models when I go flying. After a handful of flights with the TTX610, I linked my Tactic TTX850 computer transmitter to the same TR624 receiver. The Sensei manual shows the programming settings that are necessary for the WISE system.
The RTF version of the Sensei FS includes a 6-channel Tactic TTX610 transmitter and TR624 receiver. The TTX610 works well, but I eventually switched to my more adjustable TTX850.
Another advantage of using a more capable radio like the TTX850 is that it allows triple rates that can be selected individually during flight. You can fly with mid-rate ailerons, high-rate elevator and low-rate rudder if that’s what you like.
Both the TTX610 and TTX850 can be linked to other Tactic radios in a master/slave arrangement. This allows an instructor with his own transmitter to take over control of the model if the student gets into trouble. Transfer of control is done by the instructor and is as simple as releasing a spring-loaded switch. Tactic transmitters can be linked via a physical cable or wirelessly.
One thing the manual overlooks in the radio programming section is that channel 5 operates a servo-driven door on the bottom of the Sensei. It can be used to drop streamers or toy parachutists. You’ll just need to assign a switch to this channel to make it work.
This servo-actuated door on the bottom of the Sensei can be used to drop streamers or toy parachutists from the belly. Just don’t take your eyes off of the airplane!
If you’re new to flying, you’ll probably want to ignore the drop feature for a while. All too often, pilots who drop things watch what they dropped rather than their airplane. It’s a fun feature, and one that will keep the Sensei FS interesting even after you’re a competent flyer. But it’s probably an unnecessary distraction in the beginning.
The WISE system performs exactly as advertised, but do not consider this capability as a substitute for proper training. There are several aspects of learning to fly RC for which no artificial stabilizer can compensate.
WISE is great for undoing control mistakes and bringing a plane back to level flight.
WISE is great for undoing control mistakes and bringing a plane back to level flight. This helps to avoid crashes, which is the main concern for most new pilots. Mitigating crashes is a good thing, but other, less intuitive challenges are equally at play. New pilots can often be flustered to the point of inaction. In that case, the stability afforded by WISE may just leave the frazzled pilot watching their plane fly off into the horizon. A calm, experienced voice is usually all it takes to get a rookie out of this mess. Likewise, an instructor will help explain the nuances and etiquette of RC flight.
While WISE and other stabilization systems remove a lot of burden on new pilots and soften the learning curve, having an instructor is still your best bet for a quick and comprehensive flying education. Most RC clubs offer free instruction. Go to the Academy of Model Aeronautics website to find an RC club in your area.
Terry spent 15 years as an engineer at the Johnson Space Center. He is now a freelance writer living in Lubbock, Texas. Visit his website at TerryDunn.org and follow Terry on Twitter: @weirdflight