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Sunday, February 19, 2012

Head2Head - E-Flite UMX Gee Bee R-2 with AS3X vs. Great Planes Gee Bee R-1

Two new Gee Bees are available at about the same fly-away price, it's time to compare the E-Flite UMX Gee Bee R-2 BNF (EFGBR2) to the new Great Planes Gee Bee R-1 RxR (GPGBR1). I took the opportunity to fly them both back to back in light wind for an apples-to-apples test. Here is how they stack up.
The $170 street price E-Flite UMX Gee Bee R-2 (left) has a more graceful, rounded cowling.  E-Flite contrived the wing ribs, presumably to strengthen the micro's thin undercambered foam wing.  The $140 sreet price Great Planes Gee Bee R-1 (right) includes a thick airfoil cross-section and scale black cheater lines between red and black
First, the most obvious difference is the size and quality of construction. Fit and finish is a contest between the EFGBR2's fluffy, pebbled-finish beer cooler Styrofoam and the GPGBR1's tough and durable, smooth finish EPO hobby-grade aircraft foam, which is no contest.

Component quality is simply night and day. The EFGBR2's receiver, 5A ESC, AS3X gyros and servos are all on the same ($90) board which is only replaceable as a single unit. It also ties the plane to only one type of radio. The ESC is overstressed as shipped, occasionally shutting down on takeoff and making a reasonable life expectancy suspect. The ($30) 2S 180-size motor is fairly specific to micros, though it is modular if de-soldered. The two ($13.50) external servos are delicate with exposed gearing and a very poor record of reliability.
The AS3X gyro system is an interesting addition to the EFGBR2, it will be discussed in the flying qualities section.

In contrast, the GPGBR1 uses industry standard components: a ($26) 3-4S 3530 light weight motor, a ($50) Silver Series 3-4S 35-40A ESC with switching BEC, and standard ($8.50) entry-level servos. All are much higher quality then the UMX equivalents and can be replaced or upgraded individually.
GPGBR1 (I painted the radial)
While the build quality and workmanship of the EFGBR2 is impressive for a micro, the of the GPGBR1 is bigger and better in basically every respect. Additionally, the EFGBR2 is only semi-scale, the wing planform and airfoil cross-section is not true to the original, though it has a vintage look. The GPGBR1 is an excellent scale rendition, with a lot more detail enabled by it's larger size and mass.

The GPGBR1 wields a huge advantage in overall quality. You get roughly 10x the airplane for the money: 3.6 oz compared to 36 oz (in 4S form).

In the air:

Competition is a great thing. Without both of these planes the full range of RC possibilities would not be shown. The two share their color scheme; that's where most similarities end.

Overall Impressions:

The E-Flite R-2 is a miniature technology demonstrator. Amazed that this micro can fly at all, innocent bystanders stare in shock as the bouncy red bauble pops off the ground and bee-lines for the tree tops. It’s vintage portrait looks unnaturally solid in the air, as the 3-axis gyro computer stabilization system adds to the high tech feel of the tiny plane. With an ultra micro roar, a full throttle buzz zips by in frantic slow motion. The pass takes enough time for the battery to slightly flatten its pitch, sounding audibly weaker. But like an energetic flea at the circus, the eager little bug ups the ante by performing effortless loops, rolls and poses.

Onlookers involuntarily clap and smile. Girlfriends cling to boyfriends and shriek, “Isn’t that CUTE??”

After pushing the battery way too far for the pure fun of it, you bend the gyro stabilized arc toward high key, then trim and float around to a forced landing. In the flare you request any left-overs the motor might give-up for a tad more rudder control as the wheels tap pavement. Roll-out is a little longer than the 5 feet you planned, it takes like 10 feet to stop.


The Great Planes R-1 is a true-to-scale Golden Age racer. Takeoff is reminiscent of a warbird, you won’t feel comfortable challenging its slow speed rudder effectiveness with the motor at full grunt. Balance rudder with rising throttle to get ‘er moving with enough directional control. It’s all pretty tense as the plane lumbers airborne, part throttle and already gathering speed. At that instant all RC fliers have the same thought, “Landing could be interesting, I should’ve driven to a dry lake bed.”

As the plane builds momentum and bends back around to nose-on, you can’t help but push it up to feel the crescendo. The plane streaks by like a wild boar in Italian bicycle racing apparel. Pulling into the vertical trades kenetic for potential fast and furious. Before pulling the plane onto its back and over the top, you ponder the wing area, is it sufficient to keep Pumba from borrowing into the ground on the backside? Turns out, it's not a problem. At full sprint the plane is as nimble as a pig in hula skirt. Trim way forward and it blows by with a nasty growl, just a few feet off the ground with the nose slightly below level.

Onlookers involuntarily seek cover. Girlfriends cling to boyfriends and shriek, “Isn’t that DANGEROUS??” 

Step by Step Breakdown:

Both planes are easy to take off, with the UMX being the easier of the two as AS3X effectively helps compensate for the Gee Bee's large right-rudder requirement.

Once airborne, both planes are surprisingly nimble and highly aerobatic. The EFGBR2's flight path is clearly gyro-guided at times, removing some feedback and feel, but the plane flies very well in little or no wind.  Loops, rolls, hammerheads, inverted flight, knife edge flight are excellently handled. Stalls are a different story, the plane becomes unruly, particularly in yaw when it gets too slow. High speed passes are surprising fast, at least for a pip-squeak.

The GPGBR1 is big and it flies even bigger. It's legitimately fast for a parkflyer, and very well controlled at speed. Aerobatics are surprisingly nimble at cruise speed and higher, but the plane also gets mushy when slow.

Reynolds Number makes the larger plane more controllable than the micro. AS3X is helpful to the micro in that respect, but it is no substitute for larger scale.  The GPGBR1 flies a lot better and more predictably in virtually every category of flight.

The tiny EFGBR2 is obviously more affected by winds, and it doesn't handle wind particularly well for a 2S micro. AS3X is supposed to help, and it probably does help, but not enough to let the little blow fish frolic in turbulent air. Instead it weather vanes and the nose sways left-right.  The Gee Bee's primary aerodynamic challenge is a loss of rudder authority when slow due to the large fuselage blanking the rudder, resulting in uncommanded left yaw. This results from a lack of airflow, not a lack of control movement, so AS3X is ineffective in countering it.

The GPGBR1 takes moderate wind (10+ mph) in stride, with plenty of mass, speed and power to plow through.  It is also clumsy when slow, but developing stalls give plenty of signals and time to recover before dropping both a wing and the nose.

Landing the UMX is much easier than the parkflyer.  AS3X provides compensating rudder control until authority is lost, making the plane easier to keep straight as long as you keep part throttle.  The plane is very easy to land unless you approach a stall before the wheels start spinning.  If you try to flare high and slow, the UMX will formally to introduce you to whatever is well left of course.  Hopefully it isn't too hard. 

The GPGBR1 is a lot more challenging to land, especially right-side-up (see more on that in my review).  But it is also a lot tougher and takes low speed abuse in stride.  Establishing a proper glide path is tricky.  Using idle power can cause an alarming sink rate to develop, resulting in a hard high bounce.   Leave-in too much power and you'll have too much speed, resulting in a soft higher bounce.  In fact, just about every technique results in a high bounce.  Then another, and another.  Eventually, the bounces get small enough to call it a landing.  Just remember, the landing isn't over til the Gee Bee says it's over, and there always seems to be just enough speed left over to do one more outside loop.


I've summarized and quantified the world as I see it in the chart below:
The Great Planes Gee Bee R-1 RxR wins this H2H with a slam dunk--unless your flying space is smaller than a football field.

E-Flite UMX Gee Bee R-2 BNF - Flight Review
Great Planes Gee Bee R-1 RxR 38.5" - Flight Review

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