E-flite UM 4-Site

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UM 4-site

The E-Flite Ultra Micro 4-Site is a fully aerobatic indoor model, with enough power to prop-hang.


  • Wingspan: 15.2 in (386mm)
  • Overall Length: 17.5 in (445mm)
  • Wing Area: 87.5 sq in (5.64 sq dm)
  • Flying Weight: 1.25 oz (35.5 g)
  • Motor Size: 8.5mm coreless brushed (included)
  • Servos: Spektrum AS2000L: two integrated on the AR6400L and two independent for ailerons
  • Prop Size: 130mm x 70mm
  • Speed Control : Brushed controller integrated on the AR6400L
  • Recommended Battery: 1S 150mAh (2 included)

The model is made from 2mm depron and braced with thin (0.5mm) carbon fibre rods, with small plastic parts in key areas (like the engine mount and wheel axles). It is fairly tough but will not survive regular crashes.

The spots most likely to be damaged are the leading edges of the wings (if you hit something sharp) and where the rear of the top wing is glued to the 'canopy'.

The prop-shaft can bend, but can be replaced (the UM Sukhoi shaft is the same).

Pilots who have not flown a 3D model before are usually surprised that the model will not turn without the rudder, unless it's banked at least 70-80 degrees. Experienced 3D pilots will enjoy the accurate knife edge flight, but often find such a small model harder to hover than they are used to.

The large motor places a heavy load on the batteries, and in cold weather the ESC pulses and cuts out after a few minutes. 15c or higher, 150-250mAh cells would be ideal.

The neutral CG location is with the battery at the rear of the velcro. The velcro is very strong and care must be taken to avoid damaging the model while removing the battery.

To bind the model to a DSM2 transmitter, plug the model battery in with the Tx off. The Rx should start flashing after a second or two. When it's flashing, switch on the transmitter in bind mode. When the Rx LED is on solidly, the model is bound.

The AR6400 normally uses the two aileron servos just as ailerons, but they can be used as flaperons if your transmitter supports it. To switch between these two modes:

  • Switch on the transmitter (after binding)
  • Set the throttle to full
  • Aileron full left
  • Elevator full up (i.e. stick down) (ensure you are not in low-rates)
  • Power up the model and wait a few seconds.
  • After one aileron reverses, unplug the model.

With the DX7, you will need to reverse channel 6. (elevator-flap mixing instuctions go here!)

Alternative Batteries

The motor draw a maximum of about 1.7amps, so more powerful batteries are required than for any of the other E-flite/parkzone indoor models. 150mAh 10c batteries are not really enough, especially in cold weather. The motor pulses and cuts off early as the voltage sags when you hover.

Good alternative batteries are:

Brushless conversion

A 5g motor, with a Kv of around 4000 should be about right.


This model is available is a number of different packages:

  • BNF (Bind'N'Fly) - no transmitter, but you get a 4-port charger and 2 batteries.
  • PNP (Plug'N'Play)- no transmitter, charger or batteries but the plane is ready to go.