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Sunday, February 6, 2011

E-flight UMX Extra 300 BNF

The E-flight UMX Extra 300 is a very lightweight half foam/half mylar offering in the indoor 3D arena (or to a much lesser extent and no wind whatsoever, outdoor). 

To make the super light and super flimsy construction technique viable, thin carbon fiber rods reinforce the underside of the wing in truss form, with a single rod protruding forward from the CG to the tip of the nose.  Despite the most vague resemblance to an aircraft that actually has an interior, the "Extra 300" branding looks nice with the white star field on red mylar fused to one side of the foam stencil frame.  The other side of the wing and fuse are left uncovered in bare white foam.

Overall, the construction method simply doesn't work.  The plane is fairly light, but incredibly weak in certain areas which become apparent very quickly.  The wings are so pliable, that the slightest miss, generating just a few ounces of force, perhaps on a landing or getting sucked toward a wall by Bernoulli, will twist them to the point of tearing the foam and the mylar.  Within an hour of hovering practice, I had ripped both wings at the point where the leading edge meets the fuse, and one wing at the tip.  One wheel pant simulator had torn.  A few pieces of glossy Scotch tape a tiny dab of foam safe CA made those problems go away.  Why couldn't E-flight do that?  Or better yet, sell airframe designs that aren't known junk.

The specs for the 300 are as follows:

Wingspan: 16.8 in (427mm)
Overall Length: 19.4 in (494mm)
Wing Area: 74 sq in (4.8 sq dm)
Flying Weight: 1.2 oz (32.5g)
Motor Size: 8.5mm Coreless Brushed
Trim Scheme Colors: Red, Grey, Clear, Black
Prop Size: 130mm x 70mm
Recommended Battery: 3.7V 1-Cell 150mAh LiPo
Approx. Flying Duration: 4-8 minutes
Scale: Ultra Micro
Minimum Age Recommendation: 14 years
Experience Level: Advanced
Recommended Environment: Indoor/Outdoor
Assembly Time: Less than 1 Hour
Is Assembly Required: No

No radio is included.

It's all a bit strange.  Compare to the Hobbyzone Champ, which is an extremely strong, molded foam truly scale build:  The Champ has a 22.5" span (1/3rd longer), more wing area, and the same flying weight as the UMX 300 when flying times are equalized.  The Champ has a higher top speed but doesn't have quite the same T:W, but it could with the same gear reduction and larger prop.  The Champ sells for half and includes a 2.4 GHz radio.  Something is terribly wrong with the design philosophy unpinning this airplane.

E-flight needs to reevaluate their ridiculous pricing, there is $10 of airframe and maybe $10 of electronics here, retail price is $210, street price is $160, 9.5 to 1 retail markup.  A 200% markup would bring E-flight inline with industry, and suggest a fair street price of about $40.  I assess this plane as a monumental rip off.  

Strength Comparison:

HobbyZone Champ
Wingspan: 22.5 in.
Wing Area: 71 sq in.
Weight 1.3 oz
Flying Time: 12-15 minutes

E-Flight UMX Extra300
Wingspan: 16.8 in.
Wing Area: 70 sq in.
Weight 1.2 oz
Flying Time: 4-6 minutes

Coke Bottles
Span: 16.5"
Contents: 16.9 Oz of black chemical joy

The Champ wing barely flexes under it's on weight.

Extra 300 wants to fold under it's own weight.  This is after Scotch taping all edges. 
The mice add up to 7.5 oz.  I successfully added a hard drive for a total of 17.8 oz.
Forget 7.5 oz, a AA battery is enough to fold the Extra 300. 

E-flight needs to go back to the drawing board to figure out why larger airframes weigh the same, are 20x stronger, and sell for 1/3rd the price.

The Extra flies well, and has no problem hovering for the first half of the battery life.  E-flight claims "t is slow and light enough to fly extreme 3D maneuvers in spaces no larger than a dining or conference room."  That is not true.  You can hover the plane in a dining room, hanging on the prop, but it is too fast to fly on the wing inside a large house.  That leaves indoor community center or outside in dead calm winds as the primary workable venue for this plane.  

In fairness, E-flight says the plane is only for experts.  So in non-fairness, that's probably to keep them from paying money out to the intermediates and advanced novices who can effortlessly handle this extraordinarily easy-flying airplane, but tear it apart after a few delicate  mishaps.

While I have been hovering around the house with the 300's rather loud, aggressive buzz, the winds have not cooperated to complete the flying portion of this review.  This only emphasizes my point that this in not a satisfactory "dining room" flyer.

(...time passes...)

So at this point, I know readers are thinking, well, this plane is going to get an F for sure.  Not so fast.  The plane performs beautifully outdoors, and would truly excel in a gym.  Speed is well controlled with the large, gear-reduced prop, lines are straight, hovering is controlled and powerful, and turn radius is, well, non-existent by any definition that requires the center post of the circle to be outside the dimensions of the aircraft.   Flat turns progress indefinitely, given a little more radius slack than is initially possible.  Throws are exceptional and inputs are mostly linear to the stops, not causing a lot of unexpected, off-axis side-effects.  Full back stick can snap roll into a tapered-wing stall, but stall speed is fairly difficult to find and under-fly.  Multiple aileron rolls stay axial and uncoupled. Knife edge loops happen without much drama, indicating an excellent thrust to weight ratio.   Parachute landings are easy.  The plane is one spectacular 3D flier. 

Simply put, the UMX is the best micro 3D flier I've flown outside of a simulator, and it hangs, literally (and for real, which is worth a lot), with any bizarre contraption I've flown in a sim.  Stunning fun in a cul-de-sac or small field.  The lack of Mylar on one side is no doubt cheap, but also seems to serve as a decent speed brake to keep speeds relatively slow even with full power applied.  High alpha flight was easy to stop cold about 45 degrees nose high at 60% throttle, into tonight's light breeze (~4 knots).  

This plane should be relatively easy the novice-enthusiast to handle, as long as throws are reduced by a third or more with 50%+ expo applied.  If you understand what that means, new aerobatic fliers shouldn't hesitate to try the UMX Extra 300 over grass.   The light mass of the airplane makes any old attitude grass landing very forgiving, even with the planes embarrassingly low build quality.  But tape around the wing edges, and reinforce the leading edge where it meets the fuselage, first.

Not surprisingly, the plane quickly developed a bit of a rough spot in the reduction gear.  This is fairly common with cheap brushed motors and gears, even within the cheap Horizon micro servos, which are hanging on so far.

This plane is a tough grade. The build quality absolutely sux, making the price point just plain stupid. As I've shown above, other planes with more wing area and the same flying weight, test up to 20x stronger. Horizon is to be admonished for their new trend toward dirt poor product quality, ionospheric pricing, corner-cutting and resulting terrible value. At the same time, it is reasonably difficult to crash the 300 in a large gym-type of venue or outside based on a magical turn radius and low stall speed, and hitting grass with the light mass should prove forgiving indeed. So with a solid F- for build quality, D for price, and A+ for flight characteristics, I average that to a B+ (recommended) since airplanes are meant to be flown.

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