Written by Terry Dunn Pilot’s Choice Product Review As seen in the Summer 2020 issue of Park Pilot
SPECIFICATIONS:
Type: Ultramicro sport/3D model Wingspan: 27.6 inches Wing area: 119 square inches Length: 19.3 inches Needed to complete: Six-plus-channel DSM2/DSMX transmitter; 2S 280 mAh 30C LiPo battery and charger Minimum flying area: Sports field Power system: 3,400 Kv outrunner brushless motor (included); 4.7 x 2.8 three-blade propeller (included); E-flite 2S 280 mAh 30C LiPo battery Flying weight: 4.2 ounces Wing loading: 5.1 ounces per square foot Flight time: 5 to 7 minutes Price: $139.99 Info: horizonhobby.com Features: >> Uniquely capable and versatile so it can be flown in more places and smaller spaces >> Updated turboprop-style nose; three-blade propeller and trim scheme >> Functional oversize flaps for shorter takeoffs and landings >> Easy to fly with optional-use SAFE Select flight envelope protection >> Functional and factory-installed LED landing, navigation, and strobe lights >> The UMX Turbo Timber is a micro-size model that emulates a turboprop-powered bush plane. Its oversized tires and high wing with large flaps ensure that it looks the part. In true bush plane fashion, this model is intended to be a jack-of-all-trades that does many things well. All of the major airframe components are made of molded foam. The wingspan is 27.6 inches. In addition to the aforementioned flaps, the wing also has large ailerons. The fuselage is slightly more than 19 inches long from the tip of the spinner to the rudder’s trailing edge. This is not the first micro variant of the Timber series of models. Although the UMX Turbo Timber shares many features with its predecessor, the UMX Timber, there are some differences. Perhaps the most noticeable change is also the one that earns the newer version its “turbo” status. It is equipped with a 3,400 Kv brushless motor spinning a three-blade propeller, giving it a slight edge in power. A DSM2/DSMX-compatible receiver with integrated brushless ESC is included. The receiver also has two built-in linear servos that actuate the rudder and elevator. Two discrete servos are attached to the ailerons. Both flaps are driven by a third separate linear servo. AS3X stabilization helps this aircraft handle rough air like a larger, heavier airplane. It makes tiny corrections to keep the UMX Turbo Timber on a smooth flight path. SAFE Select stabilization is also provided. This is a useful tool for beginner pilots. When activated, SAFE limits the airplane’s maximum pitch and bank angles to help prevent overcontrolling (a common rookie mistake). SAFE also provides automatic recovery to level flight when the control sticks are released. The UMX Turbo Timber is completely factory assembled. Even the decals are preapplied. The only necessary task is binding the receiver to your transmitter. I used the transmitter setup guide suggested in the manual and linked the model to my Spektrum iX12. Power for the UMX Turbo Timber comes from a 2S 280 mAh LiPo battery. It is secured to the battery tray with hook-and-loop tape. The airplane balances well with this battery, but it will also accommodate larger batteries. I’ve used other 2S batteries up to 350 mAh for extra flight time with little noticeable decline in performance. Large exhaust pipes help give the UMX Turbo Timber its turboprop look. These plastic detail pieces are glued to the fuselage’s seam and cowling/battery hatch. Although I like the look of the exhaust pipes, they prevent easy removal of the hatch, which must be lifted upward from the front. There is not much room to grasp the hatch between the propeller and pipes. Grabbing the hatch behind the pipes makes it difficult to separate the magnets that secure it. My solution was to carefully detach the pipes from the fuselage and glue them to the hatch with 5-minute epoxy. Instead of being in the way, the pipes now provide a convenient handle for removing the hatch. The large tundra tires and steerable tail wheel allow this little model to taxi and take off from a variety of surfaces. I’ve flown it from pavement, dirt, gravel, and low-cut grass. Whatever you have will probably work. Full-scale bush planes are prized for their STOL (Short Takeoff & Landing) abilities. The UMX Turbo Timber does not disappoint in that regard. Just slam the throttle forward, feed in a little up-elevator, and it will be flying in no time. Dropping the flaps will get it airborne even faster. I have even performed takeoffs while using my transmitter’s carrying case as an ersatz runway! With SAFE enabled, the UMX Turbo Timber is a sedate flyer. It requires large control inputs just to get around the pattern. This surely helps newer pilots get a feel for the airplane. I do not think, however, that the UMX Turbo Timber is ideal for complete beginners. The model’s high power-to-weight ratio could be difficult for a rookie to manage.
With oversized tundra tires and large exhaust pipes, the UMX Turbo Timber emulates a turboprop-powered bush plane.
The power system provides adequate thrust for hovering and permits flight times of 6 minutes or more.
Terry Dunn moved the plastic exhaust pipes from the fuselage to the battery hatch to make battery access easier.
Turning SAFE off transforms the UMX Turbo Timber into a nimble sport flyer. It is capable of all of the basic aerobatic moves, such as loops, rolls, inverted flight, and Hammerheads. This model also does great knife-edge passes. My usual mix of normal flying interspersed with aerobatic shenanigans yields flight times of roughly 6 minutes with the 280 mAh battery. The UMX Turbo Timber even has enough power to hang on the propeller. I don’t consider it an all-out 3D aircraft because it lacks roll authority while hovering. That is an effect of the ailerons being outside of the propwash, but hovering is a fun trick to pull out on occasion. Dropping the large flaps will add a lot of lift and drag. You can make steep landing approaches without building speed and touch down amazingly slowly. I have a lot of fun shooting repeated touch-and-gos, trying to hit the same spot on the runway each time.
Large flaps on the UMX Turbo Timber permit short takeoffs and steep landing approaches.
Pitch trim will change when using the flaps. I found it helpful to mix down-elevator with flap movement. I use 20% elevator with flaps in the takeoff position and 30% elevator with landing flaps. Optional leading edge slats are included in the kit. These must be glued to the wing with foam-safe CA. Presumably, these devices are intended to improve the low-speed performance of the UMX Turbo Timber. I could not tell any difference in how the airplane flew with the slats installed, so I removed them. RC bush planes are popular for many of the same reasons that people admire full-scale bush planes. They are simple, no-nonsense airplanes that cover all of the basics. That premise certainly holds true for the UMX Turbo Timber. Despite its bantam size, it has a powerful motor, great control response, and all-terrain STOL capability. It is a fun, well-rounded RC airplane.
The UMX Turbo Timber has a well-rounded flight performance.
