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E-flite UMX B-17G Flying Fortress BNF with AS3X Technology

The UMX series of aircraft from E-flite and Horizon Hobby have been a complete success. In terms of good looks, ease of use, and flying qualities (especially with the introduction of AS3X), E-flite and Horizon Hobby have put themselves at the forefront of ultra micro design and development!



The UMX series of aircraft from E-flite and Horizon Hobby have been a complete success. In terms of good looks, ease of use, and flying qualities (especially with the introduction of AS3X), E-flite and Horizon Hobby have put themselves at the forefront of ultra micro design and development! With the introduction of the UMX B-17G Flying Fortress, E-Flite and Horizon Hobby have now pushed the envelope even further.

From E-flite ... The E-flite UMX B-17G Flying Fortress model is an ultra micro marvel. Not only is it the first ultra micro RC model of the famous WWII bomber, it includes innovative AS3X technology that makes flying more fun. Built into the Spektrum DSMX receiver, AS3X technology has been specially tuned to combat the effects of wind and turbulence so you get the kind of locked-in handling thats comparable to an expertly tuned airplane thats much larger. With four motors, three-blade propellers and full four-channel control plus an abundant amount of scale detail, its a replica you can fly almost anywhere.

Whether youre an intermediate park pilot looking for your first RC multi-engine experience or a scale pilot looking for a unique replica that can be flown anywhere, the E-flite UMX B-17G Flying Fortress is ideal. All you need to start flying today is your favorite 4+ channel aircraft transmitter with Spektrum 2.4GHz DSM2/DSMX technology.

It is a bit of a tall order to say any radio controlled airplane is ideal, but let see how close the E-flite UMX B-17G Flying Fortress gets to being an ideal ultra micro airframe.

Flying in full scale B-17's

There are many reasons a specific airframe might be of interest to a modeler. You might just like the way it looks or performs, or you might have some personal connection to it. The later is the reason I was very interested in reviewing the UMX B-17G. On separate occasions, I had the opportunity to take a flight on both "Fuddy Duddy" and Liberty Belle".

To state the obvious, flying in a B-17 is completely different from flying in any modern commercial aircraft. My first thought when inside of the airframe was how cramped the quarters were. There isn't much room, and you can easily see the inner structure of the airframe. The flights in both of the B-17's are something I will never forget. The rather slow acceleration down the runway with majestic takeoff to the what seemed like a too slow perfect landing had me thinking of those that had flown in B-17's many years ago for a much different purpose, especially as I looked out the window from the waist gunner position. Both flights were actually fairly smooth but very loud. I really enjoyed the sound of the 4 engines running strong. As with most things that are highlights of one's lifetime these flights seemed much too short, but the excitement still lives on today ... and even more so as I prepare the pictures for this review. Below are some pictures from flights in Both "Fuddy Duddy" and "Liberty Belle". Unfortunately, Liberty Belle was lost due to a fire in 2011. More information on both of these aircraft can be found online.

UMX B-17G Flying Fortress BNF with AS3X Technology
Length:18.3 in (465mm)
Wingspan:26.0 in (660mm)
Weight:2.75 oz (78 g)
Wing Area:87.5 sq in (5.65 sq dm)
Servos:2.3-Gram Performance Linear Long Throw Servo (included) (SPMSA2030L)
Receiver and ESC:6Ch DSMX AS3X UM Rx w/Quad motor ESC (included)
Battery:250mAh 1S 3.7V 20C LiPo Battery (Included)
Motors:(4) 6mm in runner (Geared) with counter-rotating operation with 3-blade propellers (Included)
Transmitter:Spektrum DX-18 used
Typical Flight Duration:Just over 5 minutes of mixed throttle
Available From:Horizon Hobby

Fuddy Duddy

Liberty Belle

Kit Contents

There are not many parts in the kit box mainly because the ultra micro airframe is completely built! The servos, receiver with ESC, and power systems are all factory installed into the airframe.

Kit Contents include:

  • UMX B-17 airframe, factory assembled with counter rotating power system to help eliminate the effects of torque, Servos, ESC and receiver.
  • Nosecone / Battery hatch / Chin turret.
  • Main landing gear.
  • "Retracted" landing gear.
  • Battery, battery charger, and battery charging extension.
  • Instruction manual.
  • Lithium Ion battery safety guidelines.

UMX B-17G Flying Fortress - A Closer Look!

First Impressions

E-flite has faithfully replicated the B-17G on an ultra micro scale and the first thing I noticed while removing it from the box were the nice little extra scale touches that are sometimes left off of ultra micro airframes. Let's be honest here, there are a few corners cut such as painted on windows and much less than scale landing gear, but given the size and weight of this airframe, it's nice to see things like the turret positions with guns and a counter rotating power system. The B-17 is painted better than I could have hoped for given its small foam airframe, and the decals were applied well. All of the electronics are installed and all of the control surfaces are hinged and ready to go from the factory. There is easy access to mechanically change the trim for the elevator, rudder, and ailerons. There is a separate servo for each aileron with a short and direct linkage, which is a definite advantage when looking for more precision in flight control. The only thing that gave me a slight concern at this point was the slightly flimsy horizontal stab and vertical fin. I was confident they were fine for flight, but I could easily imagine them being damaged by what would be normal hangar rash for other airframes.

Overall, I was impressed with the E-flite UMX B-17G Flying Fortress and given E-flite's track record with great flying ultra micro airframes, I had no concerns before heading out for some flights.

Getting ready for flight

There might be a temptation to skip the instruction manual since the airframe comes completely built but I would recommend against that. There is still some valuable information in it including the binding procedure, the recommended control throw settings, and the center of gravity.

Click here for the instruction manual.

I have included the binding procedure below, along with a control throw and C.G. image.

Note: The AS3X system will not activate until the throttle stick is increased to 25% for the first time.

The manual recommends mechanically centering the flight control surfaces before the initial flight. After binding, my UMX B-17G did not require any centering per se, but I had read online that a few people were experiencing an immediate climbing tendency after takeoff so I decided to start with a little down trim on the elevator.

The C.G. is measured 37mm back on the wing at the root. With the battery as far forward as I could get it and still get the nosecone to attach properly, I was slightly tail heavy. At this point I decided to fly it this way first and adjust it later if necessary. As noted earlier, I set my elevator with a little down trim.

Ready for flight

To properly arm the ESC and AS3X (after binding procedure) you need to:

  • Lower the throttle and throttle trim to the lowest setting on your transmitter.
  • Power on your transmitter and wait 5 seconds.
  • Connect the flight battery to the ESC, noting the proper polarity.
  • Keep the airframe immobile and away from wind for 5 seconds to allow the AS3X system to initialize.
  • Increase the throttle stick to 25% one time to activate the AS3X. NOTE: The first time the AS3X system is activated it might catch you off guard. It makes a lot of noise depending on how much you move the airframe.
  • You are now active and ready for flight.


Taking Off and Landing


I had been waiting for quite some time to maiden the UMX B-17G. My hope was to fly it first in the local golf dome night fly (The same golf dome used for the Horizon Hobby Indoor). But that was almost two weeks away, and some somewhat decent weather (at least for this time of year) had arrived, so I decided to head out to the local field. There was some light to moderate wind blowing but nothing I felt the UMX B-17G and AS3X couldn't handle. After taking some pictures and arming the ESC / receiver, I activated the AS3X system as outlined in the manual and set the UMX B-17G down on the runway. I slowly advanced the throttle and watched the airframe slowly accelerate as I prepared for takeoff. Before I knew it, the UMX B-17G had gracefully lifted off of the pavement (in about 5 feet) and began a gentle climb. Note: The maiden flight (outdoor) is included in the second half of the included review video. I was holding some slight down elevator to keep the climb from becoming too aggressive, but it wasn't so much that I ever felt like there was any fear of stall or control issues. The UMX B-17 will handle light to moderate winds just fine as can be seen in the video. Due to the size, weight, and drag of the airframe, when the winds get above that it is time to leave the UMX B-17 at home. Additional flights outdoors have proven to be a non-event. To take off, I simply advance the throttle and let the airframe pick up speed while slowly feeding in some up elevator. If I do this, I am always rewarded with smooth and graceful scale-like takeoffs.

Landing the UMX B-17G in outdoor conditions can prove to be a little tricky depending on the wind. The airframe is so light and draggy that wind, and in particular wind gusts, can easily bump this airframe around. When landing in wind, I try not to fight the gusts too much and rely on the AS3X. Having said that, the AS3X seems to have a slower reaction in flight given the nature of the airframe so the tendency is to try to manually correct it too quickly. To land outdoor in windy conditions, I slowly decrease the throttle and feed in a minimal amount of up elevator. I keep the power on all the way through touch down and only begin to lower the throttle to an idle until after the landing rollout. In low to no wind conditions landings are a stress free event. Without the wind to bump the airframe around and slow it down, landings can be incredibly smooth following the steps outlined above but with slightly less throttle input.


The UMX B-17G really shines in indoor or in light to no wind conditions. The only thing that caught me off guard slightly was trying to taxi around to set up for takeoff. I hadn't really noticed in the outdoor setting, because I was always pointing the nose into the wind and just taking off straight ahead, but the tail wheel is fixed and the rudder does not provide significant guidance until you have fairly decent forward momentum. Once I was comfortable with the speed I needed to get proper "steering", it became much less of an issue. Taking off indoors or in light wind conditions is ideal. It is so easy that it simply is just advancing the throttle and slightly pulling back on the elevator. The airframe has no tendency to hunt for its heading on takeoff possibly due the counter rotating power system. Climb out must be relatively shallow, but the UMX B-17G will fly amazingly slow before it starts to stall.

Landing the UMX B-17G indoor is rather easy, so easy in fact it is probably the easiest UMX airframe that I have landed and I have flown just about all of the E-flite / Horizon Hobby offerings plus a few by other manufacturers. I simply line up for landing, slightly reduce the throttle while slowly adding in up elevator, and then add an ever so slight final flair just before touchdown on the main gear. Shooting graceful touch and goes with the UMX B-17G is very fun and so easy that I include maybe 4 or 5 in every flight.



(Maiden flight) After I was adjusted to the UMX B-17G's flight characteristics, I started to dial in some trim for level flight. In order to get the B-17G to fly straight and level, I needed an additional 13 or so clicks of down trim on the elevator (from the initial 7 or so "clicks" of sown elevator I started with). That might sound like an excessive amount, but when you see how little actual movement there is on these small servos and control surfaces you can understand why. After the initial trim, I became very comfortable flying the UMX B-17G even in less than ideal maiden flight weather conditions, thanks in part to the AS3X flight stabilization system. Even though my UMX B-17G was slightly tail heavy to begin with (according to the manual) and required some down elevator, it never flew like it felt tail heavy. It was never twitchy in control, stall prone, or flew with any tail down tendency at slow speed.

The B-17G flies just fine outside in no wind to moderate wind situations, but pick that wind up to a gusty and slightly above moderate condition and the power system can become slightly less than adequate. I was completely comfortable flying the UMX B-17G at this point and even made a few slower passes for the camera. As long as I was gently on the controls, I was rewarded with fairly smooth flight given the circumstances. This outdoor flight was done on the higher recommended radio setting because I just felt like I had a little more control in that environment. There was nothing at this point that lead me to believe this wouldn't be anything but a great flying aircraft. Even though I had a few outdoor flights to begin with, I never did have an outdoor flight in low to no wind until after my indoor flights. So let's jump ahead to the indoor flights so I can gush about how well this UMX B-17G flies indoor and in no to little wind situation.


As mentioned, up until my first indoor flight I had not had the opportunity to fly in a no wind or even a very low wind situation so I was really looking forward to my first indoor flights. The indoor flights (and low wind) with the UMX B-17G are a very different experience and this is where the UMX B-17G shines! Undoubtedly, you have heard from a reviewer or two about how well an airframe tracks. Well get ready, the UMX B-17 tracks like it's on rails in an indoor environment. As long as I am smooth on the controls the UMX B-17G always responds positively. Make no mistake, this is a bomber and you will not power through any aggressive maneuvers, but in an indoor environment the power system is definitely adequate and provides for nice scale like flight. Having said that, it would also be nice to have a little more power for a less than scale low pass or more aggressive climb.

One nice flight characteristic is the lack of yaw when punching the throttle for a little more power ... the response is a smooth acceleration straight ahead. In the indoor environment, I prefer the lower rate radio settings as they provide for a nice smooth gentle flight. The AS3X system does smooth out the flight characteristics some, but inside you don't hear the system "working" as it does in windy situations. I was completely confident in this airframe within a circuit of the golf dome. This is the smoothest ultra micro airframe that I have flown indoors.

Aerobatics/Special Flight Performance

The special flight performance for the UMX B-17G is the way it flies indoors and in no to little wind situations (Yes, it still flies fine outside in some wind). But beyond that, E-Flite does provide a set of "retracted" landing gear that can be swapped out for the main landing gear easily. The retracted landing gear are to be used in hand launch and belly landing situations. I did fly the UMX B-17G with the retracted gear on a couple of occasions (indoor) and found little to no difference in its flight characteristics. It might have been slightly faster, but it is hard to tell. Hand launching the UMX B-17G for those flights was an easy and completely stress free event.

Just for fun I did try a couple of non-scale maneuvers in the outdoor environment. First, I tried a loop. In order to get the bomber to loop somewhat gracefully I needed to enter a dive and then pull up fairly hard. The loop itself is not the most graceful thing I have ever seen, but then again this is a bomber with a scale-like power system, and to be honest it wasn't too bad (watch the video). I also tried some inverted flight at the top of a loop. I was able to maintain inverted flight with a bit of down elevator but I never did try for extended inverted flight because the wind was bumping it around quite a bit and well, this is a bomber so it shouldn't be doing this stuff anyway.

Is This For a Beginner?

I wouldn't recommend the UMX B-17G for a true beginner. It is rather small and can get into odd situations if you try to over control it ... and there isn't excess power available to get you out of certain situations. A modeler who has mastered a basic trainer would have no problem flying this aircraft. I do however think this would then be a great first UMX airframe for that same modeler.

Flight Video Gallery

E-Flite UMX™ B-17G Flying Fortress (indoor and outdoor) (4 min 59 sec)


In all honesty I was hoping the UMX B-17G would be a great flying aircraft that would help me relive some past personal experiences with two full scale B-17's. Not surprisingly, the UMX B-17G has proven to be a great flying airframe that is incredibly smooth in indoor or llight wind situations. The AS3X system performs admirable in more windy situations, and the aircraft is still fun to fly as long as the wind doesn't overtake the available power. I admit that while flying the UMX B-17G I often think of my past experiences flying in those B-17's and how well this models flies ... and that always puts a smile on my face.


  • Flight characteristics. The airframe is incredibly smooth in the air under no or light wind situations, and still does well in up to moderately windy situations. The AS3X performs well in all environments but really helps in windy conditions. It is easy to land.
  • Fit and finish. Paint and decals are applied well.
  • The airframe is completely factory assembled.
  • Counter rotating power system provides for smooth flight and scale-like performance.
  • Easy battery access through removable nosecone.
  • Included USB battery charger works well.
  • Decent flight time. About 6.5 minutes of mixed throttle flying on a 4 motor airframe. It probably can be pushed a bit further but I like to land when I notice the power starting dropping.
  • "Retracted" landing gear set provided for hand launch and belly landing.
  • The kit box is also a storage and transportation box.


  • More power would be nice. There really is enough power to fly this airframe in a scale-like manner but there definitely isn't excess power.
  • I realize this is an ultra micro and lack of weight is a premium but it would be nice to see a more scale set of main landing gear and wheels.
  • Two of the props on my airframe were not tracking properly and were way out of alignment. It only took a few minutes to bend them back into shape.


  • It would be nice to have a steerable tail wheel for taxiing out to and back from the flight line.

Special Thanks

Thanks to Mike Magnacca for his video services and to Gary Pace and Mark Taylor for their outdoor photo services and to Done Wise for his indoor photo services.

Last edited by kevin; Apr 12, 2015 at 09:46 PM..
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Old Apr 14, 2015, 08:29 AM
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Very nice article! Just one thing I noticed- if you look on Horizon's website, you'll find the B-17 listed at 129.99.
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Old Apr 14, 2015, 01:50 PM
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Originally Posted by Julezwatts View Post
Very nice article! Just one thing I noticed- if you look on Horizon's website, you'll find the B-17 listed at 129.99.
Thats cause they dropped the price , when it first came out it was $159
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Old Apr 14, 2015, 01:55 PM
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Thanks. Good catch, as noted the price has dropped recently (since the review was submitted). I have an email in to change it in the review.
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Old Apr 15, 2015, 02:25 AM
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While I do appreciate the B-17 and it's illustrious history, I would appreciate even more a Lockheed Supper Constellation L-1049.

Maybe I can find a wrecked B-17 for cheap, and make my own Super Connie, but it seems to me that Horizon would recognize the potential value of a sleek and graceful design such as the Connie.

As a guy that appreciates sailplanes a lot, I prefer airplanes that at least seem to be more aerodynamically efficient.

But of course as a glider guy, I have a PNF, or "Pointy Nose Fetish".

Also, it seems to me that an airplane with four motors would be best served with the 2S system. If you want "scale" performance, just throttle back. But I'd love to snap-roll a Super Connie, even though that isn't "scale" flying.
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Old Apr 15, 2015, 06:45 AM
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Very cool! Great review! I wish I had a place to do indoor flying, how cool would that be...

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Old Apr 16, 2015, 10:12 AM
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It's a nice video. The B-17 is great. I like mine. As mentioned above a Super Connie would be nice to. Or maybe even a DC3.

1S of course. I like the 1s Planes. I don't fly my 2s & 3s anymore. I'm tired of loading up the pickup and driving for an hour just for a few flights.

1s planes are good for flying at home!

Just my 2 cents worth!

the other jack!
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Old Apr 17, 2015, 05:44 PM
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This one is on my list......

My late Father flew 18 missions over Germany as the radio op and waist gunner in a B-17 G. Beautiful bird brought him home safely to father five children, the last of which was yours truly.
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Old Apr 26, 2015, 01:27 PM
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I bought the Easysky one, better flying and cheaper in price and you can also get parts for it as well
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