Horizon Hobby E-flite UMX Gee Bee R2 BNF With AS3X Technology Review

This Gee Bee R2 comes ready to Bind and Fly with four channels and AS3X technology for great control and flights from smooth to adventerous.



Weight:3.60 oz.
Wing Area:72.5 sq in
Servos:(4) 2.3g Performance linear long throw servo
Transmitter:Spektrum DX7s
Receiver:2.4GHz RX, BL ESC with Servos
Battery:2S 200mAh 25C Li-Po
Charger:DC powered Celectra 2S Li-Po charger included
Motor:180 size 3000Kv brushless outrunner
Propeller:5.25 x 3.5 electric propeller
Available From:HorizonHobby

I have owned the original Micro Beast and the new 3D Beast with AS3X technology and experienced first hand how the AS3X technology took a plane that was a challenge to fly well into a plane that flew well and was fun to fly. I was really interested in getting my hands on the UMX Gee Bee and bought one before I learned I was to review one here for E-Zone. The plane comes fully assembled and ready to bind and fly and is colorful and attention grabbing whether on a table or in the air. The plane has a wide speed range from slow to hauling fast in the high 40s. The finish on the plane is very nice and includes things to read on the fuselage and tail area that I and spectators have enjoyed. I am ready to try for an old fashion 1930's air race with take-off and five labs around the pylons. I suspect many of you will want to join me after you see this plane in action.

Kit Contents

This BNF Gee Bee R2 Kit Includes

  • Gee Bee R2 Plane Transmitter Ready
  • 2s 200mAh 25C Li-Po battery pack
  • Celectra DC 7.4V 300mAh Li-Po Balance Charger
  • Instruction Manual

Promoted Features

Promoted Features

  • Large battery hatch with magnetic lock
  • Nice scale details including wheel spats and flying wires
  • Scale paint scheme and finished pilot bust installed
  • AS3X System for smooth handling and outstanding precision
  • Full four channel control with steerable tail wheel
  • Ultra micro long-throw servos
  • Brushless 180 3,000Kv motor
  • 2s 7.4V 200mAh Li-Po battery pack
  • Balance charger @ 7.4V 300mAhs

I supplied

  • DX7s Spektrum 2.4GHz 7 channel transmitter
  • Extra 2s 7.4V 200mAh Li-Po battery packs


There is no assembly as the UMX Gee Bee comes fully assembled. I only had to charge up the flight battery, program my transmitter for my Gee Bee and bind and fly.

Charging the 7.4 Volt 200 mAh 25C Battery Pack

A Celectra 2S 7.4 Volt DC Li-Po charger was included with the plane. This is a balanced charger and the battery pack can only plug into the charger cord in the correct way. The charger being a DC charger needs a 12V power source such as a car battery. At the field I can charge the battery pack using my car battery and at home I can power the charger with my AC to DC power converter. The supplied charger charges at 300 mAh which is 1.5C for the 200mAh battery pack. The pack can be charged at up to 600mAhs or 3C if I had a charger with a connector that would match my battery. A near fully discharged battery pack takes about 50-60 minutes to fully charge with the supplied charger. I ordered extra battery packs to increase my flight time. The charger uses LEDs to convey how it is working and they have a chart that explains the charging operation and how LEDs on the charger show what is happening.

If you don't have an AC to 12V DC converter you can buy one from Horizon Hobby, E-flite. It is part number EFLC4000 and is a 1.5 Amp power supply that plugs into the Celectra charger. It sells for about $20.00 Spare 7.4V Li-Po battery packs are also available as part number EFLB2002S25 for under $24.00 at this time.

Per the instruction manual they recommend that the first flights be limited to 3 minutes and then you can have flights lasting up to 4.5 minutes depending on throttle management. I programmed the timer on my Spektrum DX7s transmitter to initial run for three minutes for the break-in period and now have it set for four minutes to sound a warning that it is time to land. Having spare battery packs makes landing less painful as I can insert a charged pack and resume flying at least a couple of times.


How the transmitter binds to the UMX Gee Bee R2 depends on the transmitter used, With my Spektrum DX7s I placed the transmitter in DSM2 mode. The transmitter would have done this automatically based on the receiver it was binding too. I next connected the battery pack in the plane and waited for the light on the receiver to start flashing. I then held down the binding button on the top left of my transmitter as I turn the transmitter on and keep it held down until the receiver's LED was on solidly lit. After the binding process was completed and everything turned off; I now turn on my transmitter for at least five seconds before connecting the flight battery to the receiver. Any JR or Spektrum DSM2/DSMX transmitter can bind to the AS3X DSM receiver in the UMX Gee Bee R2. Go to www.bindnfly.com for a complete list of compatible transmitters.


While the battery was charging I programmed my Spektrum DX7s transmitter for my new plane. I programmed in the name and set the timer to work from the raising and lowering of the throttle and I had it programmed for a three minute countdown initially as discussed above. I also programmed in dual rate and exponential for the Gee Bee. I followed the recommendations in the manual as listed on page 9.

High Rates

  • Ailerons 100%
  • Elevator 100%
  • Rudder 100%

Low Rates

  • Aileron 70%
  • Elevator 70%
  • Rudder 70%


  • Elevator 10% on High Rates

The next step in preparation was confirming that the Center of Gravity was properly located 26mm back from the leading edge of the wing with the battery properly installed. With that accomplished the final step was adjusting the rudder sub-trim so that the rudder was offset 1mm to the right as measured at the trailing edge. The plane was ready to fly and I went and flew it. However, before describing how she flies I want to briefly discuss the AS3X Technology.

AS3X Technology

This is my fifth AS3X equipped aircraft but only the second airplane. The first AS3X equipped plane that I had was the UMX Beast 3D and I had an original Ultra-micro Beast before that and it was easy for me to see the difference in the handling of the planes with and without AS3X. Accordingly, I rely upon my experience with my two Beasts to discuss what AS3X does for the handling of a plane.

The claims for AS3X is that: "It makes the aircraft both more stable and more agile and that the pilot doesn't have to deal intensely with flight complications such as turbulence, torque and tip stalls. That thanks to AS3X tuned to each aircraft the pilot feels ultra-smooth control even outdoors in moderate wind yet is allowed to experience exhilarating aircraft agility that feels natural and allows you to quickly build skills as an RC pilot."

As a reviewer I would like to explain how AS3X works and exactly what it does to make a plane more stable and better able to handle turbulence and torque. To that end I have watched and read everything I could find on AS3X and no where did I find a technical explanation of how it works. All the discussions I have seen to date discuss what AS3X does but not how it does it. While I am sure there are scientific explanations for what is happening I haven't found them yet. As a pilot I don't have to know how it does it, just that it consistently does it so that it can be relied upon. So far I have found it very reliable.

My original UMX Beast was easily tossed about in the wind with massive fluctuation of the wings when flying in a breeze. I felt I wasn't so much controlling her as constantly correcting her for what the wind was doing to her. My new UMX Beast with AS3X is a much more stable plane in those very same conditions. Much less wing fluctuation as when it starts to fluctuate the AS3X immediately corrects. The AS3X quickly corrects for movements caused by wind and turbulence. The corrections are performed so quickly that they occur almost as soon as they start. These self corrections made me much more in control of the plane as I never found the AS3X to delay a command I sent to the plane with my transmitter. I was directing her where I wanted her to go and not responding or correcting for a push away from my intended flight path nearly as much. It is not perfect and in strong wind gusts I do get buffeted some but not very much. I have that same control now with my UMX Gee Bee R2 Racer. Actually, for me the control seems even better in the GEE Bee then the new AS3X equipped Beast. Perhaps that is because the UMX Gee Bee seems to have more power. Thus while I can't tell you how AS3X works from a technical stand point I can confirm that it does work from my own experience. If the wind forces it toward a right bank it stops it immediately but doesn't interfere with my transmitter command to bank.


AS3X Demonstrated  11.16 MB



The UMX Gee Bee has four channel control with throttle, ailerons, rudder and elevator. It has a very wide speed range from slow to close to 45+ mph. These extremes can be seen in the videos below. I like to take advantage of the various control options. Full throttle seems faster when used in short bursts with moderate speed much of the time and with a slow pass before hitting the throttle. The instructions advised limiting my first couple of flights to three minutes and as discussed above I did that. They have also posted a technical bulletin (Posted at the end of this review.) advising to run down about ten seconds of the full charge to avoid having the Over Current Protection kick in and cause a possible crash by that circuit protection causing loss of power. I have had no problems following the recommendation but I look forward to them finding a permanent solution. I limit my flight times outdoors where I use a mixture of throttle to four minutes and then I land. This is the recommended flight time per the instruction manual and is a good reason to get some extra battery packs.

Rudder does have an interesting control effect with this plane and I strongly encourage owners to use it in conjunction with the ailerons during turns and maneuvers.

Taking Off and Landing

The plane can be launched by hand or takeoffs can be made from a hard surface. If there is wind the takeoffs should be made into the wind. The plane has tremendous power for its weight and takeoffs can be made with as little as a foot or so from a picnic table. Takeoffs from a golf course green are possible but the fairway grass proved a bit to thick and caused nose overs without damage. Landings have for the most part been uneventful but I have seen nose overs caused by indoor carpeting, golf course greens and pilot error. I have had no trouble when setting up for my landings in a pattern and landing at reduced speed and killing the throttle on touchdown and putting in full up elevator. Just as the UMX Gee Bee flies nice and smooth she takes off and lands the same way. However, don't land sideways to the wind as a strong cross wind can tip her over at touchdown and don't land her with the nose down as that often leads to a nose over. In the video below she slowly noses over after a nice landing when the wheels find some holes in the dirt/grass runway. Hard smooth surfaces are definitely the way to go if available.

Aerobatics/Special Flight Performance

The UMX Gee Bee flies like a normal size RC sport plane for most maneuvers. She can perform loops from small and tight to huge, filling the sky. I have been able to perform every maneuver that I have tried and my favorite with this plane is the banked pylon turn. It took me some practice to get to tip the plane up to where the wings were vertical, no more or less. The plane was in banked turns around an imagined pylon and a few around a very real pylon. I get a better barrel roll with aileron rudder and elevator than I do an axial roll with my Gee Bee with low battery but both can be done well with a charged battery. A half loop and a split S has been performed both inside and out but I have done my last one inside a building as I almost "landed" on the ceiling. Maneuvers are performed best with a near full battery charge as is true with most planes. Top speed appears to be about 45 MPH + with a fully charged battery. Speed seems to be even more impressive after a couple of slower laps and then hitting the gas.

Is This For a Beginner?

NO! She flies like a very nice sport plane but she is not a trainer. This plane is for the intermediate and better pilot. She is not hard to fly for an experienced pilot but she is not for the Beginner.

Flight Video/Photo Gallery

Still pictures and video of the AMA Expo in Ontario CA in Jan 2012


Still pictures from the UOP gym and video from our county fairgrounds with Jose Macias flying.




She arrived ready to bind and fly and I enjoy using the low rates for takeoffs and landings and high rates for everything in between. She can be flown indoors as shown above but I am not as aggressive as the Horizon Flight Team in the first video as I would probably hit a wall trying some of those moves. I prefer to fly my UMX Gee Bee R-2 outside. She has handled a five mile per hour breeze without any problems. I found I definitely want more battery packs and although I had two battery packs I have ordered two more. When the charger wires come back in stock I plan to but a set of them to recharge the battery packs at 3C (600mAhs) which the battery packs can handle. She is fine taking off and landing on a hard surface and has been flown off of a wood floor, concrete, vinyl flooring. a picnic table and pavement. She has taken off and landed on a golf course green (with permission) but longer grass makes takeoffs very difficult if not impossible. Warning: Flying this plane is habit forming and is definitely a step up in performance and handling from my previous ultra micros. For the intermediate and better pilot this is a blast to fly, but all too soon it is time to land and switch battery packs.

Pluses and Minuses


  • Looks Great
  • Wide speed range
  • Yank and banks for very sharp turns
  • Handles a breeze well
  • Can be flown indoors-best outdoors


  • Battery only lasts for a little over four minutes of fast flying
  • Be sure to burn off a little juice from a full charge to avoid OCP problems (See Below)

My thanks to Jose, Charles and Kirk for their assistance with the media for this review.

Technical Bulletin

Gee Bee EFLU4580

Over Current Protection

During production of the E-flite UMX Gee Bee, small tolerances of components have led to some Gee Bee models hitting the Over Current Protection (OCP) during the first initial run of a fully charged battery. When this happens, the motor will shut off as programmed to protect the electronics from an over-current condition. The servos will not stop working and you will still have control of the plane. This only happens when the battery is at a fully charged state and will not happen in the course of an entire flight.To reset the motor, the throttle needs to be cycled back to low power. After the motor has been run for a few seconds and the voltage of the battery has come down, the system will not hit OCP.

This does not occur on all models and should be checked on the ground before each flight. Larger and or higher C rating batteries are not recommended for the Gee Bee, as this could cause the power system to run above the designed limit and hit OCP. Follow the instructions below to prevent hitting OCP during a flight.

Throttle the model up to full power on the ground and let it run for 10-15 seconds. If the model hits OCP and the motor shuts down, cycle the throttle and run the motor again near full power for at least 10 more seconds. This will bring the battery voltage down low enough to prevent hitting OCP during the flight.

Horizon is working to find a long-term solution as soon as possible.

Last edited by Michael Heer; Jul 25, 2012 at 05:56 PM..
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Aug 03, 2012, 08:42 AM
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Michael Heer's Avatar
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This space reserved by author for future postings.
Last edited by Michael Heer; Aug 03, 2012 at 09:45 AM.
Aug 03, 2012, 10:43 PM
Pronoun trouble...
DismayingObservation's Avatar
I LOVE my Gee Bee and my Beast. I too had the overcurrent problem which led to some rough takeoffs; Horizon Hobby's incomparable customer service replaced the model with no questions. The replacement is a blast to fly!

If it helps, my original was one of the first ones delivered to the hobby shop back in March. I assume the new one has the updated board since there is no problem with premature cutoff.

I'd sent the prop size and motor speed to Ken Young at Subsonic Planes and the speed of this little plane is no joke. The prop speed is just under 50 MPH (80km/h).

Flying off a paved surface is a must since it will nose over every time on grass.

This is the gold standard in micro aircraft.
Jan 26, 2013, 08:37 AM
Registered User
has any one taken the undercarriage off for belly landings ?
would i have to do anything to wings as they would not have surport wires from wheels
Nov 12, 2014, 07:26 PM
Registered User
How does the Gee Bee speed compare to the Pitts or the beast? Can the BG be flown in a 75 by 75 foot area or is it tooo fast? Thanks Ron
Nov 13, 2014, 10:24 AM
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Michael Heer's Avatar
Thread OP
That is too small a space for me to fly mine and enjoy it. Might be able to do a simple circle at medium speed but that doesn't float my boat. Watch the video again. Mike H
Dec 06, 2014, 01:51 PM
Registered User
Is there any place to still pick up one of these since there discontinued
Dec 06, 2014, 04:45 PM
Extremely Twisted
Eagle2Nitro's Avatar
Originally Posted by lazer
Is there any place to still pick up one of these since there discontinued

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