I may be giving away my age, but I’ve been around RC long enough that most glider pilots would cringe at the thought of an electric motor mounted in the front of a sailplane. This was likely the same crowd that called a rudder gyro in a helicopter “cheating” and moved to have them banned at the Nats.
Today, there are electric-powered gliders at nearly every field I visit, and most modelers view electric as another way to get their sailplanes in the air. It’s less fuss than rigging a hi-start or winch or finding a towplane. It’s great that E-flite has stepped up its support for the glider crowd lately with the release of the two Mystiques: the Blanik and the soon-to-be-released Allusive. The company’s glider prices are reasonable and support from Horizon Hobby has always been outstanding.
The newest member of the Mystique family is a “back to the basics” Rudder-Electric-Spoiler (RES) version. It was released a few months after the Mystique 2.9-meter ARF. I reviewed the RES’s predecessor in the August 2013 issue of MA. The RES version is equipped only with a rudder, elevator, and spoilers and can be flown with a simple four-channel radio without any complicated sailplane programming. Don’t let the simple design fool you. Mystique designer Peter Goldsmith took third place at the AMA Nats flying a Mystique RES in the Altitude Limited Electric Soaring (ALES) class competition.
Flying with only elevator and rudder is a throw back to my early days of RC when I learned to fly on a two-meter, two-channel glider Craft Air Drifter II. The Drifter II was such a floater that landing in the same ZIP code was a chore. I had to build a new wing and took the opportunity to modify the wing by fitting spoilers. This made landing in the same neighborhood I took off from much easier!
Most modern sailplane designs utilize flaps for precision landing or a function known as crow or butterfly mixing which is a combination of dropping the flaps and reflexing the ailerons upward. This has one drawback that spoilers don’t suffer from.
Extending the flaps lowers the stall speed and slows the glider, but if you feel that you will be short, retracting the flaps when you’re too slow will dump that lift, resulting in a stall. If you’re landing with the spoilers out and feel as if you’re going to land short, you can safely retract the spoilers no matter what your airspeed and it won’t cause the glider to stall.
The Mystique has built-up wings and tail surfaces and a nicely crafted fiberglass fuselage. The wings are covered in translucent yellow and the high-quality construction and can easily be inspected. The wings have a more distinct polyhedral than its predecessor, which aids in turning without ailerons. The Mystique RES also has a larger rudder than the first edition of the Mystique.
The elevator is a full-flying stabilizer, (there is no separate stabilizer or elevator, and the entire surface moves), that is shoulder mounted—raising it out of the dirty air from the wings. The full-flying stabilizer removes the possibility of incidence problems between the main wing and the stabilizer. The only slight downside is that it needs to be properly aligned before the first flight or the glider could nose up and stall or land like a lawn dart. The Mystique has a molded outline to make alignment simple.
The wings attach to the fuselage with a 10mm-thick carbon wing-joiner rod. The wing rod goes into carbon-fiber tubes that are embedded into the wings. No wing bolts are used or needed but you do need to find some white electrical tape to hold the wings in place. I get some strange looks for taping the wings on my gliders, but this is the norm and it has worked for me for hundreds of flights on several models.
Although I wouldn’t try a competition winch launch in the pure sailplane configuration, the Mystique should have no problem with hi-starts or casual winch launching.
The wings are equipped with spoilers that considerably reduce the lift provided by the wings. The spoilers are situated on the wing outboard of the stabilizer. This keeps the disturbed air from the spoilers from drastically reducing elevator effectiveness when the spoilers are deployed.
The fuselage is molded fiberglass and appears to be finished in white gel coat with no visible seam line. To addressing a potential problem with pushrod flex, the new fuselage has another former installed roughly halfway back for an extremely ridgid pushrod installation. Horizon clearly listens to customer feedback.
With all the components laid out on my bench, I was anxious to start building the Mystique.
Construction
Manuals for E-flite kits typically are among the best in the business, and the Mystique’s manual is no exception. It is well written and clearly illustrated. I’ll be using Zap brand thin and medium CA, and Z-Poxy 15-minute and 30-minute epoxy available from Frank Tiano Enterprises to build the Mystique. Please ensure you have adequate ventilation while working with any modeling chemicals.
The only hinging that needs to be done is the rudder. Lubricate the hinge joint with petroleum jelly. (I warm up a small batch until it liquefies, then dip the hinge pivots into it.) This not only lubricates the hinges, but prevents the epoxy from making them seize.
To mix the 30-minute Z-Poxy, I cut bamboo skewers into sections and use the sharp point to pack the fuselage and control surface holes with epoxy before inserting the hinges. Working the surface back and forth several times while the glue is wet will align the hinges. The recessed hinges leave a gap-free installation. I prepared the rudder and spoiler control horns and the wing antirotation pins at the same time, and glued everything in one batch.
The elevator installation for the Mystique RES is identical to that of the previously released Mystique. You can glue the stabilizer halves in place but E-flite recommends, and I agree, that using a glue stick on the carbon joiner rods will make the installation removable. Coat the joiner rods with the glue stick and insert the stabilizer halves.
Installing the servos in the fuselage presents no problems. The connection at the elevator bellcrank is a tight fit but little tinkering was needed to install it. After the tail connections are made, you can install the access hatch with clear tape. When the servo installation was complete and everything was centered, I used Z-42 threadlocker to secure the jam nuts on the pushrods.
I will assemble the Mystique using the recommended E-flite power systems including the new 1,000 Kv motor, a 60-amp ESC, and a 3,300 mAh 3S battery. The recommended motor doesn’t require the shaft to be reversed. Motor installation is easy and I used Z-42 threadlocker to secure the engine bolts and propeller spinner bolt. Folding the propeller blades back against the fuselage and tightening the propeller nut will result in perfect clearance between the fuselage and spinner.
When the fuselage construction is complete, it’s time to prepare the wings. Because of the simplicity of the RES design, the only steps are to install the spoiler servos and the index pins. The spoilers require thin wing servos, a couple of extensions, and a Y harness. The wing has pull strings for the servo extensions and the servos are glued to their respective hatch covers.
Scuff the servo gluing surface and the hatch before gluing them in place. If you ever need to remove the servo from the hatch, slightly bowing the hatch cover will typically break them loose. Connecting the linkage and getting the proper spoiler throw takes some tinkering, partly because it is a small space in which to work.
The Mystiques are designed to be built with a power system or as a pure sailplane. If the unpowered option is chosen, a nose cone and towhook are included in the kit. If you choose to go this route, be prepared to add enough lead in the front to make up for the missing battery, ESC, and motor.
The CG location didn’t work out with the layout in the manual, but was obtained by relocating the receiver behind the rudder and elevator servos. This not only put some weight farther back, but provided room to move the battery far enough back to get the recommended CG location.
The RES Mystique made a great first model to learn the programming on my new DX-9 radio. Although the DX-9 is full of high-end sailplane features, the setup for the RES is simple. The power pilot in me likes the propeller to move when I advance the throttle stick, so I assigned the throttle to the throttle stick and the spoilers to the left-hand slider.
The one change I made to the recommended setup was to mix the rudder stick to the aileron stick. That way, if my brain decided to use my left thumb for rudder, the rudder would still respond.
I set up a count-up timer that would call out my times and another voice alert on the high and low control rates. I can’t wait to explore the voice and telemetry features as I become accustomed to this radio.
Based on my previous experiences, I knew that the ESC would be factory set for non-brake mode. With a powered sailplane you want the propeller to stop when the power is off, so program the ESC for hard brake. Anything less won’t stop the propeller. That’s the only ESC programming change you need to make for the Mystique.
Power system bench tests showed that the Mystique pulls 52 amps and produces 583 watts at full throttle with a fully charged battery. The result was 130 watts per pound, which should pull the Mystique aloft with authority.
Flying
Perfect weather the day after a build is completed is rare, even in Florida. The Mystique was finished on a Thursday evening and Friday was predicted to have clear blue skies, light winds, and temperatures hovering in the low 70s. The fact that the calendar had just turned to March was a bonus, but the time that you read this spring should be in full swing everywhere.
With the power system and range tests out of the way, I topped off the battery and headed out for a test hop. My goal for the first flight was trimming, a CG check, and determining if any compensation mixes were required for throttle and spoilers.
I advanced the throttle to half power and gave the Mystique a gentle, straight-and-level toss. If you add much more throttle, you risk damaging the fuselage sides. When it was moving out straight and level, I selected full throttle and established a 45° climb.
Although it’s not a rocket, the Mystique climbs well. Because I had to hold down-elevator, I knew that some elevator mixed to throttle would be required. This is not a surprise because the flat-bottom, high-lift wing, makes them go faster and they produce list and pitch up.
Most of my powered gliders need some elevator compensation when throttle is applied. I chopped power at approximately 200 feet and leveled off. The Mystique settled in and didn’t need anything but two clicks of down-trim.
I wanted to find out how the Mystique handled with only rudder and elevator. I was surprised that tight spiral turns that are essential to working light lift at low altitude were possible, and the Mystique didn’t lose much altitude when turning—even in the zero lift conditions in which I was flying. More importantly, it didn’t fall off or stall when I got it up on a wing.
With a nudge of down-elevator, the Mystique gathers speed and makes a pleasant whistling sound that several people at the quiet morning field commented on.
Although I still had some altitude, I deployed the spoilers and they are quite effective. The nose instantly dropped so I knew that I had to add some up-elevator mix, but when holding some up-elevator, the Mystique would quickly lose altitude and not build up speed. Pull the spoilers in, and the Mystique resumes floating. I landed and decided to wait for the sun to heat things up and try thermaling.
The next launch had the Mystique climbing straight and true with the down-elevator mix programmed in. At full power, the Mystique climbed nearly vertical.
With the power chopped, I set off in search of lift and in no time was circling in a thermal. The Mystique reacts well to lift and the yellow covering presents well against blue or cloudy skies. Flying out of the thermal or fully deploying the spoilers will break the lift and allow you to quickly descend if the Mystique starts getting too far away for comfort.
I put a small white towel on the ground and tried some spot landings. Modulating the spoilers let me land consistently within 10 feet of my spot, and a few times I was within half of that.
Because we were having a fly-in at my field the next day, I charged the battery and played “pass the transmitter.” Everyone who had a turn on the Mystique enjoyed it. A few pilots who typically fly electric-powered aircraft hooked a thermal and worked some lift with it, which showed me that the Mystique would be a good platform for learning thermal soaring.
Conclusion
The Mystique is a pleasure to fly and a real floater. The simple RES setup means you don’t need a fancy sailplane radio to successfully fly it. The built-up wings and surfaces and the fiberglass fuselage are top quality, and the Mystique can be built in less than six hours.
When you consider that the Mystique RES can be competitive in ALES contests for half the price of many other sailplanes in its class, and is backed by Horizon Hobby’s support, the Mystique is an excellent value. If you don’t want to compete, the Mystique is a great step up for Radian owners who are looking for a built-up airframe that is attractive to own and fun to fly.
The Mystique RES requires little assembly and is fun to fly on calm days. There are few wires to hook up and switches to think about, and it’s relaxing to fly. The 1,000 Kv motor provides ample power.
