Hobby RC: Testing the E-Flite UMX Timber

By Terry Dunn

Ultra-micros have advanced dramatically in recent years.

I've been a fan of ultra-micro RC airplanes since they first became available several years ago. At first, it was just about the cool factor of flying an itty-bitty model, even if it couldn't do much. But ultra-micros have advanced dramatically in recent years. They are now powerful, practical, and versatile flying machines with features that rival or surpass larger models. The subject of this review, the UMX Timber, is a prime example.

About the UMX Timber

The UMX Timber ($130) is a Bind-N-Fly model with a 27.6" (700mm) wingspan and a flying weight of only 4.3 ounces (121g). It comes with everything except a compatible radio transmitter, flight battery, and charger. Other than bolting on the landing gear and setting up your radio, all of the pre-flight tasks are done for you.

Like all of E-flite's other UMX models, the Timber is made of molded foam components. It is adorned with a mixture of paint and stickers. I'm not a fan of the stickers. While I like the color scheme, the stickers have a glossier sheen than the foam and are wrinkled in numerous areas. There is definitely some headroom for cosmetic improvement.

This model has a variety of bright LED lights installed in the wings and fuselage. They emulate the navigation lights found on full-scale airplanes. The lights are somewhat crude, with exposed wires and circuit boards. Their inclusion seems to be an afterthought. I'm sure some flyers like the lights. I wouldn't mind if they were omitted.

E-flite's UMX Timber is a small and lightweight RC airplane that is factory assembled.

One of the most noticeable and unusual aspects of the UMX Timber is the pair of cartoonish tires slung underneath. The tires seem a bit less awkward if you're familiar with the rugged full-scale airplanes made famous by Alaskan bush pilots. Those aircraft have similarly-oversized tires that let them take off and land on very rough ground. The UMX Timber's tires serve the same purpose. Whereas most micro-sized models require a paved runway or a hand launch, the UMX Timber is much less picky. I've been flying off of a grass runway with no problem. None of my other micros can do that.

The UMX Timber is equipped with wing flaps that provide a huge impact to the model's slow speed performance.

Another unique feature of the UMX Timber is that it is factory-equipped with wing flaps. This forced me to rethink my opinion of flaps for small models. I am not typically in favor of them. I think that most parkflyer and micro models fly slowly enough without flaps. In many cases, adding flaps introduces unnecessary weight and complexity with no real benefit. The UMX Timber is different. While it doesn't need flaps, they really do have a significant impact on the model's slow-speed performance. They're definitely a worthwhile feature here.

The UMX Timber is propelled by a tiny brushless motor spinning a 5"-diameter (127mm) propeller. Power comes from a 2-cell 280mAh LiPo battery. It's a potent little system.

Removing the top hatch reveals a tiny (but powerful) brushless motor, flight battery, and additional LEDs.

The built-in electronics brick includes a Spektrum-compatible receiver, two linear servos (used for elevator and rudder), and an electronic speed control for the motor. Three separate linear servos are used to control the ailerons (2) and flaps (1).

A peek at the underside of the wing shows one of the aileron servos as well as the wiring for wingtip LEDs.

There are two flight modes programmed into the receiver: SAFE and AS3X. I've mentioned the differences between SAFE and AS3X in previous articles, so I won't dig too deeply here. While they are both artificial stabilization systems, there are significant differences in what they do. AS3X detects and corrects for small bobbles in the model's flight path to make the flight smoother. SAFE, on the other hand, automatically brings the model to straight and level flight whenever the pilots releases the controls. Used correctly, SAFE can be a helpful learning tool for new pilots. With that said, I don't think that the UMX Timber would be a very good first model. The larger, 1.5 meter variant of the Timber (and a competent instructor) is probably more appropriate.

I linked the UMX Timber to my Spektrum DX8 transmitter. A setup chart in the manual made things easy. I did not have any hiccups. Additionally, I found that the recommended battery provides the correct balance point. I also experimented with other 2-cell batteries up to 325mAh. All fit in the battery compartment and balanced well.

I'm not a fan of the stickers on the UMX Timber because of their glossy sheen and numerous wrinkles.

Flying the UMX Timber

The airplane has gobs of power. Rolls and loops are very comfortable. Even sustained inverted flight is no sweat.

As mentioned previously, the UMX Timber's oversized tires allow it to operate from relatively rough grass. It does require some technique, however. I found that I was rarely able to ease in power for a gradual takeoff without the airplane getting stuck or nosing over. It's best to just jam the throttle and get into the air quickly. It's not an issue when flying from smoother surfaces.

The airplane has gobs of power. It will climb straight up if you want. All of that thrust helps with those quick takeoffs and opens up a lot of aerobatic potential as well. Rolls and loops are very comfortable. Even sustained inverted flight is no sweat.

The maneuver that impresses me the most when flying the UMX Timber is knife-edge flight. All you have to do is roll the airplane onto either side and apply a little opposite rudder. It will knife-edge fast or slow with minimal control inputs.

Those huge tires may look a little strange, but they allow the UMX Timber to operate from grass runways. Most ultra-micro models require a smooth surface.

There are two flap settings outlined in the manual. It is truly fun to explore how they each impact the flight performance of the airplane. Dropping the flaps to the first setting noticeably slows the UMX Timber but doesn't affect its controllability. You can maneuver the model at very slow speeds without any indication of a wing stall.

This brings me to one of my favorite activities with the UMX Timber. I pick a small stretch of runway, drop the flaps a notch and see how quickly I can do multiple touch-and-goes. I brutishly manhandle the airplane while flying circuits well within the footprint of your average living room.

Lowering flaps to the second setting adds even more drag and lift. There is so much drag, in fact, that I think there are only a few applications where using them is very practical. It's still a useful tool to keep in your back pocket. And you can do some uniquely fun things with full flaps.

One "flap trick" I have learned is to approach the runway at a high altitude. Twenty-five feet (7.6m), fifty feet (15.2m), higher…it doesn't matter. As I fly over the runway threshold, I apply full flaps, chop the throttle, and dive straight for the ground. The flaps limit the airplane's terminal dive velocity to feather-like speeds. Pulling out of the dive a few feet above the ground leaves me with enough momentum for a gentle touchdown on the runway.

The UMX Timber has an extremely wide performance range. This is largely due to its built-in artificial stability systems.

E-flite provides optional leading edge slats that can be glued to the wing. These slats are supposed to allow the model to fly even slower. I glued on the slats after a few outings with the stock wing. Honestly, I could not detect any improvement in slow speed performance with the slats installed. There may actually be a difference, but I couldn't tell. I have since removed the slats.

Several of my outings with the UMX Timber have been on relatively windy days. It's really not a big deal with this model. Although the airplane is small and lightweight, the AS3X makes it behave like a larger machine. This has been my experience with AS3X in other models as well. Wind can even be used to your advantage with this model. Can you say, "Backwards landing?"

I fly in AS3X mode most of the time. While I generally think of SAFE mode as a beginner-only tool, I have discovered some other applications where it is useful. The first example derived from my attempt to mount a camera to the UMX Timber. It's a really small and light camera, but it was immediately apparent that its presence was not appreciated by the airplane. I was having a tough time keeping things under control just long enough to come back for a landing. I decided to switch to SAFE mode and my workload immediately became much easier. The gyros did all of the work. I even stayed airborne a little more than necessary since it was no longer a struggle. I intend to tow banners and gliders with the UMX Timber, so SAFE mode will likely help me there as well.

Optional leading edge slats are provided with the model. I tried them, but didn't find any appreciable difference in flight characteristics.

Another fun thing in SAFE mode is to ignore the right control stick. With the gyros keeping the airplane level, it can be flown using only the throttle and rudder controls on the left stick. Add power to climb, reduce to descend, and use rudder to point the model in the direction you want it to go. I've had models in the past that were capable of throttle/rudder flight by virtue of their intrinsic aerodynamic stability. But those planes did not have the aerobatic chops of the UMX Timber in AS3X mode. The artificial stability offered by SAFE gives you both options.

Final Approach

I like ultra-micro models a lot. I've always found something to appreciate about them. While the novelty of their diminutive size is often reason enough to enjoy them, you typically have to concede to some of their size-induced limitations. The UMX Timber, however, represents a significant milestone in the progress of these models. There is no longer any substantial tradeoff required to fly an ultra-micro. It can fly in wind. It can operate from grass fields. It's powerful. It's aerobatic and also stable. This model has all of the qualities that you would normally seek in a sport airplane, just in a much smaller package, which opens up more potential flying sites.

It's not my nature to gush about a review subject, but I've really taken a shine to the UMX Timber. It checks all of the boxes for an ultra-micro model--and a few more. It's a great all-around airplane. There is still some room for improvement, however, in the looks department. I'll be glad when stickers are a thing of the ultra-micro past. Other than that, it's difficult to find fault with this well-rounded jack-of-all-trades.

Terry is a freelance writer living in Buffalo, NY. Visit his website at TerryDunn.org and follow him on Twitter and Facebook. You can also hear Terry talk about RC hobbies as one of the hosts of the RC Roundtable podcast.