Horizon Hobby E-flite UMX Ultrix BNF Basic


Written by Terry Dunn Pilot’s Choice Product Review As seen in the Summer 2020 issue of Park Pilot

Bonus Video

SPECIFICATIONS:

Type: Ultramicro sport model Wingspan: 13.5 inches Wing area: 85.3 inches Length: 12.9 inches Needed to complete: Five-plus-channel DSM2/DSMX-compatible transmitter; 1S 500 mAh 25C LiPo battery; charger Minimum flying area: Sports field Power system: Two 500 Kv outrunner brushless motors (included); counter-rotating 60-mm diameter (2.4-inch) propellers (included); E-flite 1S 500 mAh 25C LiPo battery Flying weight: 2.4 ounces Wing loading: 4.1 ounces per square foot Flight time: 5 to 8 minutes Price: $119.99 Info: horizonhobby.com Features: >> Innovative and unique design capable of smooth sport, aerobatic, and 3D flying >> Differential thrust for yaw control to perform flat spins and other maneuvers >> Extremely durable yet lightweight, fully molded EPP airframe >> Powerful twin brushless motors deliver the power to hover and climb out vertically >> Fully factory assembled and ready to fly

Two of these tiny 10-mm diameter brushless motors provide impressive thrust and speed for the UMX Ultrix.


>> With a wingspan of only 13.5 inches, the UMX Ultrix from E-flite is a micro-size sport flyer with big-time aerobatic chops. This flying wing is made of molded EPP foam. It has two vertical stabilizers that simply slide into pockets on the top side of the wing. They can be easily removed for transport and storage. In fact, the airplane’s packaging doubles as a sturdy, low-profile carrying case. All of the stickers that you see are factory applied. There are contrasting colors on the top and bottom to improve in-flight visual orientation. The stickers on my model were straight and well adhered. Like most flying wings, the UMX Ultrix uses elevons for pitch and roll control. Two long-throw linear servos actuate these control surfaces. This model has yaw control as well. Differential thrust of the twin brushless motors provides tremendous yaw authority at all flying speeds.

The micro receiver/ESC included with the UMX Ultrix includes AS3X and SAFE Select stabilization.

 


 

Terry Dunn stiffened the elevon pushrods with 1 mm carbon-fiber rods to improve the control response at high speed.

 


 

The UMX Ultrix uses a 1S 500 mAh LiPo battery.


Speaking of the motors, these electron burners are unbelievably tiny! Each motor has an outer diameter of just 10 mm (0.4 inches). They spin counter-rotating propellers that measure only 60 mm (2.4 inches) in diameter. A magnetically secured hatch on the belly of the model provides access to the receiver/ESC and battery. The recommended battery is an E-flite 1S 500 mAh 25C LiPo with a JST connector. A cavity in the foam holds the battery securely with just a friction fit. No hook-and-loop tape is needed. The UMX Ultrix is a BNF (Bind-N-Fly) model, so it is factory equipped with a DSMX/DSM2-compatible receiver. This receiver also provides AS3X and SAFE Select stabilization. AS3X is always active. It compensates for the effects of turbulent air and keeps the Ultrix on a smoother flight path. SAFE is intended to help less-experienced modelers fly the UMX Ultrix. When SAFE is enabled, the airplane has pitch and bank limits that prevent it from climbing or rolling too sharply. It will also self-level when the control sticks are released. You can enable or disable SAFE on the fly using a switch on your transmitter. This airplane is designed for hand launches and belly landings on grass. Traditional landing gear is not included, but the model does include a removable wire skid. This piece goes into a plastic mount in the nose. It protects the belly, propellers, and servos if you land on paved surfaces. No assembly is required to get the UMX Ultrix ready for flight. You only need to configure your radio system. I set up a profile in my Spektrum iX12 according to the chart in the airplane’s manual and linked it to the receiver. Even if you are an ace pilot, I suggest that you activate SAFE for hand launches. This will ensure that you get a stable launch and have plenty of time to get both hands back on the transmitter. The technology is built in, so you might as well take advantage of it. Be sure to disable SAFE when you trim the UMX Ultrix. I found that the model required a slight bit of reflex in the elevons to maintain level flight. According to E-flite’s suggestion, I later zeroed the trims on the transmitter and adjusted the pushrod lengths to keep the elevons at their trimmed position. Flying the UMX Ultrix with SAFE enabled makes it relatively docile. Don’t get me wrong; it is still a nimble model. There is plenty of control to keep it in a small area. If you’ve never used differential thrust, this is a good way to get a feel for it. The full performance potential of the UMX Ultrix is unleashed when you deactivate SAFE. The airplane has a super-low wing loading, which enables it to fly at incredibly slow speeds. But the UMX Ultrix can go fast too. Pushing the throttle forward will get this little wing zipping around the park in a hurry!

The UMX Ultrix has a wide speed range and is capable of dizzying aerobatics.


Control response is quite good. High-rate throws on the elevons will produce tight loops and rolls that blur the wingtips. Introducing differential thrust into your maneuvers will enable wicked-flat spins, pirouetting Hammerheads, insane snap rolls, and other wild aerobatics. This is the type of model that allows you to just throw the control sticks to the corners and see what happens. It recovers almost instantly from any bad attitude. During my first few flights, I felt like the UMX Ultrix wasn’t locked in when flying at high speed. I suspected that the pushrods were flexing under load. This situation improved noticeably after I stiffened the pushrods by adding 1 mm carbon-fiber rods with heat-shrink tubing and CA glue. Accidents are bound to happen as you explore the extremely wide flight envelope of the UMX Ultrix. That’s okay because this model is very damage resistant. First of all, it is lightweight (2.3 ounces), so there is not much momentum when it hits the ground. The protruding EPP nose section acts like a bumper that helps absorb impacts. A spare set of propellers is included as well. The UMX Ultrix might be small, but it has a lot of guts. It has a well-matched power system and excellent control authority. The toughness of its EPP foam airframe eases the anxiety of trying new maneuvers. It is a fun model with which to cut loose at your local park or schoolyard for stress-free aerobatics.

The UMX Ultrix is capable of wild aerobatic moves that belie its small stature.

 

 

 

 

 

 

 

 

 

 

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