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Great Planes Electrifly XPD-8 EDF Flying Wing Brushed Electric Ducted Fan ARF Review

Mitch Gerdish tries out a new electric ducted fan almost-ready-to-fly flying wing offering from Great Planes and finds a new appreciation for this under-utilized niche in electric flight. GP promotes this as amazingly fast and capable, with the STOCK BRUSHED power package. Can it meet their claims?

Splash

Introduction


Wingspan:28" (710mm)
Wing Area:209 sq. in. (13.4dm^2)
Weight:12.625 oz. as built (354g)
Length:15" (380mm)
Wing Loading:8.7 oz/sq. ft.
Servos:Hitec HS-55
Transmitter:Hitec Eclipse 7
Receiver:Hitec Micro 05S
Battery:Great Planes 11.1V 910mAh Lipo (Part #: GPMP0605)
Motor:Great Planes 370BB Brushed Motor (included)
ESC:Great Planes ElectriFly C-25 (Part #: GPMM2025)
Manufacturer:GreatPlanes
Available Online From:Tower Hobbies

I was very interested to see this new release from Great Planes -- an EDF -- a nice size, a unique looking package, appeared to truly be ARF, plus -- GP claims great performance, awesome roll rate and some serious top end speed...all in an inexpensive package with the included stock brushed motor. That's quite a tall order...can they fulfill it?

Kit Contents and Required Items

The box arrived at my house after having experienced some less-than-gentle handling. But all was safe and sound in the well packed kit.

I immediately noticed the cute little details in this very ARF kit. Stickers on the ailerons warning not to step there as well as details on how to evacuate the pilot were fun to see.

The first step in the instruction manual has to do with "Decisions You Must Make." Here are the decisions I made:

Motor: The XPD-8 kit I received was the ARF that includes the HyperFlow EDF Unit. This EDF unit comes with a 370 sized motor. I'll be honest -- when I first heard I was reviewing this kit, I expected to receive a cheap brushed speed-400-type can motor like those I used to use before going brushless. But, the 370 BB motor provided in the kit is not your average brushed motor. The magnets are very strong, and the motor has replaceable brushes. In other words, this is not your average 370/400 size motor. I also appreciated the fact that it had bullet connectors pre-installed that mated with the female connectors on the ESC.

... I expected to receive a cheap brushed 400 can motor like those I used to use before going brushless. ... The magnets are very strong, and the motor has replaceable brushes. In other words, this is not your average 400-sized motor.

ESC: GreatPlanes provided their ElectriFly C-25 mini brushed motor ESC for the review. This ESC was also a nice surprise. It's programmable for Nickel or Lithium cells (2S, 3S, or 4S), and it has a programmable brake. Additionally, it has a safety feature that requires moving the stick to and from full throttle before the motor is active.

Battery: GreatPlanes provided their 11.1V 910mAh lipo battery pack. This is the first ElectriFly lipo pack I've owned and I'm impressed with the build quality. Additionally, it has their built-in safe charge module which means I can use my existing Apache 2500 LiPo charger instead of having to buy a special charger or modify one of my other balancing chargers.

Radio Equipment: For radio equipment, I dug around in my parts bins and came up with 2 HS-55 servos. The recommended servos (Futaba S3110) weigh 7.7g compared to my 9g HS-55s. But, otherwise, the HS-55s fit perfectly in the servo bays precut into the wings.

For a receiver, I bought a Hitec Micro 05S receiver. This is a very small single conversion full range receiver. The recommended receiver (Futaba R114F) weighs 10.2g without crystal. The Micro 05S weighs 8.6g. So, there was no considerable difference in the weight of my radio equipment when compared to the recommended equipment.

Assembly

BUILDING NOTE: If you use tape to hold things in place when building a model, be aware that scotch tape will take off the black paint on the top of the fuselage. Blue painters tape doesn't appear to be as bad, but it will take some paint off. The bottom line is that if you plan on using tape that you want to remove later, only use it in places that are not seen when the model is complete (e.g. under the canopy).

Building the EDF Unit - 40 minutes including motor checks and programming the ESC

The EDF unit has a separate set of instructions. The first thing to note is that, when built using the stock motor for the XPD-8, you will end up with extra parts left in the box. Specifically, the stator extension (part #2), front housing flange (#6), and the 20mm brushless motor adapter (#7) are not used for the stock brushed motor set up. Also, there are two extra fan rotor adapters (#9).

The assembly is pretty straight forward. Be sure to select the fan rotor adapter that best fits your motor's shaft. In step #3, the instructions suggest making a small hole in the fan housing through which you can insert your allen wrench for tightening the set screws in the fan adapter. I didn't bother making this hole. I simply screwed in the set screws until just before they would be too tight to fit on the motor shaft, slipped it on the shaft, and then tightened the set screws from the front of the fan housing using the short end of my right angled allen wrench.

When attaching the aft cone and the rotor cone, I applied a couple of drops of medium CA to the lip of the cones and then placed them onto the fan unit. This seems to work better than putting the cone in place and then dabbing CA to the seam since the CA doesn't want to wick into the seam like it does when working with wood.

NOTE: The nacelle is not needed for the XPD-8. So, don't install it.

When the unit was complete, I programmed the ESC and checked the motor as per the instructions. When looking at the rotor cone from an angle, I noticed some wobble, but the motor felt stable and I couldn't detect any strange vibrations or rubbing. However, when I flew the plane I did notice a loud vibration at lower throttle settings. In retrospect, I may have installed the wrong fan rotor adapter. So, be sure to use the one that is the tightest fit. One post I saw on RCGroups.com noted that there may be burrs in the adaptor's shaft hole which may make you think you are using the right adaptor when you are not. So, really check this step very carefully when building the EDF.

Wing - 15 minutes

The only real step here is to attach the wing tips. I glued them in place using CA around the tabs which fit into the underside of the wing. Then I applied a fillet of epoxy along the top of the joint between the wing tip and the wing.

Fuselage - 80 minutes

To be honest, I'm not sure what took 80 minutes for this portion of the build. There's really not much to it. But, I probably spent time looking for drill bits, waiting for the soldering iron to warm up, thinking about how I wanted to do things, etc. The bottom line is that it's not a complicated build. I'm just slow.

The first step here was to install the fan unit in the duct. As per the instructions I marked the location of the fan unit on the underside of the plane -- in case I ever needed to cut out the EDF for servicing. This is less likely if using a brushless motor, but with the brushed 370 BB there may come a day when I need to replace the brushes.

Once the location was marked, I applied 30 minute epoxy to the fuselage where the fan housing sat and then placed the EDF in place. Using 30 minute epoxy gave me plenty of time to make sure the fan unit was seated properly.

With the duct channel assembled, I cut the prescribed holes for the motor wires and servo wires. Although the instructions had a very nice "Expert Tip" about using a metal tubing to cut the holes, I just used drill bits and my hobby knife.

Note, the servos I'm using already had EZ links installed on the servo horns. So, I decided to use them with the EZ links. EZ links are not part of the kit. Installing the servos took me about 20 minutes.

Unique Control Rod Setup

Once the servos were installed, I installed the control horns and assembled the control arms. I will admit that I debated using a single control rod instead of the two-piece shrink-wrapped assembled control rods included with the kit. I decided to trust the folks at GreatPlanes and went with the two-piece control rods. Once completed, I tugged on the two ends a bit and my fears were calmed. The control rod should hold up fine.

Completion

One problem I had was that the canopy hold-down magnets came loose from the canopy. Even after gluing them back in, I couldn't get the canopy to snap down enough to make me confident the canopy wouldn't come off in flight. So, I ended up using some small pieces of velcro along the sides at the aft end of the canopy. Based on posts here on RCGroups.com, others have had no problem using the magnet hold downs.

For the RX antenna, I routed it under the right aileron hinge. I tried a drop of foam safe CA, but it actually melted the hinge tape. So, I then used canopy glue which is a watered down version of white glue.

I ended up with an all up weight of 12.625oz. The manual gives a 12-13oz AUW range. So, I was happy I hit the mark.

Using a Whattmeter, I measured 11.4 amps at 11.1 volts at full throttle static. This produces about 126 watts of power. At 0.79 pounds, this means I'm getting about 160 watts/pound -- COOL! This is a pretty darn good number -- fantastic considering a stock brushed motor -- and tells me the plane should have more than ample power.

One may ask why use a 25A ESC if the current is only 11.4A. Well, I did notice that when I initially kicked the throttle to full, I had a peak current of around 16A for a brief period. So the 25A ESC provides added headroom. That said, a 20A ESC would also work. But, I would probably not go with an ESC rated for less than 18A.

Throws and CG, Reflex

I set the low rates and the high rates as per the manual. On the maiden flight I had to trim in some up elevator. After landing I noted that this resulted in the elevons being positioned such that the bottom of the elevons were lined up with the seam between the top and bottom of the duct channel. This gives the plane a bit of reflex which is generally needed with flying wings. I had forgotten this golden flying wing rule and thus had to trim in some up elevator during the first flight.

Also, for low rates, I would suggest turning down the ailerons from the 8mm throws recommended in the manual to 6mm or 5mm. The plane has a wickedly fast roll rate even with the low rate settings. If nothing else, dial in some exponential if you can. As far as the elevator throws are concerned, I think the recommended throws are fine.

Flying

Taking Off and Landing

For the maiden flights, I had a friend handlaunch the plane for me. It's a good thing I did because even with low rates, the controls proved very responsive. So, having my driving hand on the sticks from the get-go let me handle some overcorrections on my part during the launch. Once I was settled in, I climbed to altitude and trimmed out the plane. As noted above, I had to trim in some up elevator. Additionally, a couple of clicks of right were added.

Slow flight was easy, and landings were simple, with no fear of tip stalls or other concerns.

There's something very exciting about the sound of an EDF and at full throttle, and the XPD-8 with the HyperFlow EDF unit does not disappoint. Although I hear a vibration at lower throttle settings, once I approach full throttle the vibration disappears. And, I find myself pretty much flying this plane at full or very close to full throttle anyway.

The power was quite impressive, period, even without thinking about this being a stock, brushed motor. When you realize this is an inexpensive model with an inexpensive brushed power package, it's an even bigger "wow".

Aerobatics/Special Flight Performance

Loops are nice and big. Vertical is quite good. Inverted is easy and stable. Additionally, slow flight performance is solid. Therefore, I had no fears of tip stalls or similar problems during landing. It glides reasonably well on final and lands easily.

Where the XPD-8 really shines (or freaks you out) is in its roll rate.
Even on low rates, the XPD-8 rolls crazy fast.

I've had other planes that have a fast roll rate, but I've always been able to exit rolls the same way I started them. With the XPD-8, I came out of my first roll attempt (with the stick kicked all the way over) upside down and a bit disoriented. Later flights I added some expo and realized that it wasn't necessary to move the sticks too far and still get exciting roll rates.

The XPD-8 literature makes a point about it's speed. It is a relatively fast plane. Some modelers have done sound-based measurements on RCGroups.com using doppler programs, which have shown it coming close to it's speed claims. Unfortunately, I wasn't able to verify the speed. But, looking at the video, you can see that the plane is no slouch. And, given it's relatively small size, it gets small fast enough as it is.

With the stock brushed motor as used in the review, I found the plane is more than adequately powered. It's not overpowered as would be the case with some hot brushless motor in there, but it's definitely not underpowered. The climb is strong enough that I never felt worried that I would get myself in a situation I couldn't pull out of.

After flying for a little over 5 minutes at full throttle, I found the resting voltage of the Electrifly lipo pack to be 3.6V per cell. This means I could go a bit deeper into the pack. So, I think 6 minutes at full throttle is very do-able with longer flights if using throttle management. Also, based on my Whattmeter, I put 800mAh back into the pack when I recharged it.

Is This For a Beginner?

This plane is NOT for the beginner. Although it's an easy build, the responsiveness of the plane and the relatively fast speed probably makes the XPD-8 at least a third plane.

Flight Video/Photo Gallery

Downloads

For more fun video, including a feel for just how quick she is, check out Great Planes' flight video too!

Conclusion

Overall, I'm very happy with the XPD-8. As a kit, it's hard to beat a quick building ARF like this for only $100, especially including a motor and fan unit. The brushed motor did surprisingly well, performance was good PERIOD, not just "good for a brushed motor". As a plane, it's size makes it a great grab-and-go plane with enough performance to keep me from getting bored when flying it. And, the fact that it has that extra "wow" factor from being an EDF makes it a great addition to the hangar.

Last edited by AMCross; Aug 02, 2006 at 03:13 PM..

Discussion

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Old Aug 02, 2006, 03:43 PM
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pda4you's Avatar
USA, TX, Trophy Club
Joined May 2002
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Great review Mitch.

I had this out of the box in the LHS and it just about came home with me! I thought it would make a perfect vacation plane - my wife.....that's another opinion!

Mike
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Old Aug 02, 2006, 09:04 PM
OFF TOPIC POSTER
Des Moines IA
Joined Dec 2005
4,804 Posts
Is it made out of epp sorry i didnt read every thing ? and how was the launch?
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Old Aug 03, 2006, 07:46 AM
Mitch G's Avatar
Naperville, IL USA
Joined Nov 2000
1,886 Posts
Good questions.
I can never remember which is EPP and which is EPS, but it's made out of what I would call a dense form of styrofoam.

The launches are fine once trimmed. Again, the responsiveness does mean you have to be careful not to overcontrol if the launch wasn't exactly straight and level, but the stock setup has more than enough power to climb to altitude quickly.


Mitch
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Old Aug 03, 2006, 09:51 AM
Yey epoxy!
Cheech151337's Avatar
Auburn, NY
Joined Oct 2005
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Quote:
Originally Posted by Mitch G
I can never remember which is EPP and which is EPS, but it's made out of what I would call a dense form of styrofoam.
Someone that knows about this stuff should do a writeup on wikipedia, their listings on styrofoam are really lacking.

Edit: Did a little more searching and found some more information under Polypropylene and Polystyrene.
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Old Aug 03, 2006, 03:19 PM
resU deretsigeR
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Dublin Ca
Joined Aug 2004
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EPS

Expanded Polystyrene Foam, for example, Dow Chemical Company's Styrofoam

This is like the foam coffie cups and ice chests

EPP

Extruded polypropylene, a foam form of polypropylene, used in airmodelling for its light weight and durability


This is like the spongy foam used to pack electronics (provided they did not cheap out and use Polystyrene also used for backing of car bumpers.
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Old Aug 04, 2006, 01:02 AM
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has anyone ran one brushless?
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Old Aug 04, 2006, 11:39 AM
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extruded polypropylene = coroplast
expanded polypropylene = EPP

I could be wrong, it's quite often the case. I'll go away now.
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Old Aug 07, 2006, 02:26 PM
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loved the bluegrass music!
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Old Aug 14, 2006, 12:54 PM
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Joined Oct 2005
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kinda dissapointed

I am sorry to flame but the brushed motor that comes in the kit is complete junk! I would strongly recommend going brushless in the beginning... unless our kit was just a lemon = you WILL be dissapointed in the reliability of the motor. The plane itself flies well, and its not too bad even for a beginner. The canopy size is just a joke and more of a pain in the butt than anything. We basically had to cut the top out of the canopy to fit our electronics and battery. It might be better if you used the exact electronics from great planes. Overall we give the kit with the brushed motor a 6 out of 10 for all the problems we had with the motor.
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Old Aug 14, 2006, 01:39 PM
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Solo -- GP is known in the industry as one of the best about standing behind their products and taking care of "lemon" type issues. I'd strongly suggest sending your motor back and let them replace it for you.

AMC
no-longer-affiliated-with-gp
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Old Aug 14, 2006, 02:46 PM
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AM, yes you are right and they will warranty the motor... never-the-less the motor is of marginal quality and people need to know that because the review is one of the reasons the plane was purchased. We found the above review not accurate (at least for us) and would recommend a brushless setup from the start. Also you will find you need more room in the canopy unless you get exactly the electronics it seems made for it... so If you have your own stuff you prob will be cutting the canopy right away... and taping the canopy down for sure.
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Old Aug 16, 2006, 10:01 AM
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Solorsix,
I don't know what kind of problems you had with the motor in your fan unit, and going brushless from the begining is of course always an option for "MORE POWER...POWER...POWER"... But, as far as having to cut the canopy and install your own stuff, I have had plenty of occasions to send out kits that I represent to people for their review, or just for fun only to have them call me and tell me it does'nt fly like it should. Then I find out that they are using none of the reccommended equipement and in fact may have done something like install ailerons on a plane designed for rudder elevator only, and did not even hinge the rudder, or against written directions, paint several coats of color spray paint on top and bottom of the kit when directions clearly say not to do that and they complain it's sluggish. All I am trying to say is that I feel certain that the XB would be less aggravating if the exact equipment that was made for it were installed in it. I personally enjoy adapting my own stuff to kits or homebuilt planes because I dont have the reccommended equipment and can't get it right away or can't afford it at the time. It's fun, but then I don't expect the plane to fly exactly like it was billed to fly. Keep us all posted on how yours goes and post some video if you can. Thanks

Bo
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Old Aug 16, 2006, 10:18 AM
Mitch G's Avatar
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Joined Nov 2000
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I appreciate your feedback about the review. If you are having troubles with the motor, then it's a problem with that specific motor. The review plane is still flying strong with the stock motor - in fact this past weekend while flying it, a seasoned e-flyer offered to buy it if I ever planned on selling it. Of course, motor replacement is not a trivial exercise given the need to cut the plane open, but I would strongly urge you to send the motor back for replacement.

As far as the canopy is concerned, it is a tight fit under there. As indicated in the review I had to carve out some of the canopy foam to make the stuff fit. BUT, it is also critical to use small components that are on par with the recommended GreatPlanes items.

I hope you can get the bugs worked out since it is a fun and unique plane to fly.


Mitch
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Old Aug 16, 2006, 10:31 AM
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Joined Oct 2005
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Yeah we are using the electri-fly lipo and the electri-fly 30 amp ESC...(the hobby store was out of the 20 amp) and a GWS naro RX which is very small.
The 30 amp ESC being a tiny bit bigger is a nightmare to fit. We had a great maiden until motor cutout and crash which hammered the nose. We found the problem had to be the motor so... one flight = cut up the plane. We found a brush stuck. The brush was stuck in what looked like dried solder rosin. just removing the spring caused the spring to break...LOL! well, unstuck the brush and put a new spring in, tested and flew again same thing... half way threw a flight and motor quit... this time the end cap was a little melted?? and found the same brush stuck again. and again the plane was not in a place to coast in so it crashed mangling the wing this time.
I will also add that like what was stated in the review = you can be meticulous in building the fan unit and it will still shake like a gerbil in a key west pet shop.
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