FMS F3A Explorer - Diamond Hobby

A year in the making, this new FMS model was developed with input from Diamond Hobby. The result is a groundbreaking, receiver-ready pattern plane!



FMS F3A Explorer PNP

Wingspan:40.2" (1020mm)
Wing Area:297 sq in (19.2 sq dm)
Flying Weight:2.2 lb (1000g)
Length:44" (1120mm)
Construction:Expanded polyolefin airframe; fiberglass reinforcement spars; polycarbonate canopy; plastic cowl, vortex generators, pilot bust, wheel pants and strut covers; plastic wheels with rubber tires; nylon propeller with plastic spinner
Wing Loading:.12 oz/sq in (52.1g/sq dm)
Servos:Four FMS FMS-091 9g analog
Transmitter:Airtronics SD-10GS FHSS-3 ten-channel 2.4GHz computerized aircraft
Receiver:Airtronics 92674 FHSS-1 seven-channel aircraft
Battery:Predator 2200mAh 3S 35C lithium polymer with Deans Ultra-Plug connector and JST-XH balancing tap
Motor:FMS 3536; 1150Kv
Propeller:FMS 11x5.5E
ESC:FMS 40A brushless
Operator Skill Level/Age:Intermediate/Advanced, 14+
Manufacturer:FMS Model, 3/F, Building B, 3rd Industry Zone, Matigang, Dalingshan Town, Dongguan City, PRC
Available From:Diamond Hobby LLC, 553 Capital Circle SW, Unit 4, Tallahassee, Florida 32304
Price (USD):$169.99 with free shipping in the contiguous US plus applicable tax

The news from FMS just keeps getting better.

Pattern fliers, put your hands together for the fantastic new FMS F3A Explorer PNP. This all-EPO beauty goes from box to field with very little work, needing only a transmitter, receiver and a popular 2200mAh 3S li-po.

Not only does the Explorer feature the unmistakable, almost organic lines of an F3A pattern flier, it goes two better.

Referred to as a "canalyser" in the video linked below, the distinctive, vestigial looking upper wing is designed to enhance rudder control. Since it has no control surfaces of its own, the upper wing is easily removed with two screws for storage and transport. It's also a fuctional wing with an airfoil, lightening the loading on the main wing as well as offering a bit of lift on its own.

It's not exactly a biplane since the upper wing is so much smaller than the main wing. It's more of what's referred to as a "sesquiplane." However, research shows that a sequiplane generally has a far narrower lower wing.

As for the lower wing itself, it features some aerodynamic aids in the form of wingtip vortex generators designed to increase lift, especially at low speeds.

The model is going to be guided by a terrific new radio. I'd mentioned in a previous FMS/Diamond review that Diamond Hobby's Jim Ogorek is a dyed-in-the-wool Airtronics fan. Thanks to my friend Mike Greenshields, vice president of marketing for Global Hobby Distributors, I walked out of the 2015 AMA Expo with a top-of-the-line Airtronics SD-10GS ten-channel aircraft radio for this and future reviews! As with the SD-6G I've used in other reviews, the ergonomics of the SD-10GS were designed with input from Mike. He gladly took the time to show off his terrific work and believe me, was I ever impressed.


The Explorer comes as a true plug-n-play:

  • Preassembled fuselage with motor, ESC, servos and tail wheel
  • Main wing halves with preinstalled servos and carbon fiber spar guide tubes
  • Preinstalled fiberglass spar in the upper wing
  • Preinstalled fiberglass spar guide tubes in the horizontal stabilizer halves
  • Preassembled landing gear
  • Fiberglass wing and horizontal stabilizer spars
  • Full hardware package with extra hardware
  • APC-style 11x5.5 electric propeller with adapter rings and three-piece spinner
  • Foam glue for installation of the wingtip vortex generators
  • Small phillips screwdriver
  • Photo illustrated assembly and setup manual

Needed to complete the model:

  • Computerized 2.4GHz aircraft radio system, four channels or greater
  • 2200mAh 3S 25-35C lithium polymer battery and charger
  • #1 and #2 phillips screwdrivers for larger screws
  • Self-adhesive hook-and-loop tape
  • Blue liquid thread locking compound (optional but recommended)

When I popped the lid of the shipping carton, I didn't see the box lid but rather the bottom. Diamond Hobby was kind enough to forward one of their Predator 2200mAh 3S 35C li-pos and it was a perfect fit in one of the recesses in the shipping tray.

Here it is by itself:

Removing the display box from the shipping box gave me my first look at the box lid. It's a good looking box, but that strange "FMS Aerobatic" script, the mock PNP wing logo (as if it were a trademark) and pilot skill level meter were distractions.

I've pointed out in previous reviews that the box doesn't fly and the contents do. Everything was well packed. No damage to anything.

FMS does a great job with EPO molding. Everything was smoothly finished and injection marks were at a minimum. Paint and decals were nicely applied as well, but the doubled-up "Explorer" scripts on the fuselage and tail clash with the overall style of this model. A high performance model such as this calls for big, bold sans serif block lettering or anything bolder and more forceful.

Then, there are the graphics themselves.

They're green. Really green. The main color is almost the exact shade of bright green used for chroma key effects in television production and it's contrasted with two shades of blue. I immediately concluded that keeping this model oriented in flight would not prove to be a problem, an important consideration when flying a model such as this in the way it was meant to be flown. My assumption later proved to be correct. There's no missing the Explorer when it's in the air and the contrast between colors makes for a beautiful presentation.

Other, more thoughtful touches abounded. There's a nicely detailed pilot figure and an instrument panel decal already installed in the cockpit. The figure is that of a jet fighter pilot and not a civilian, but it adds a nice scale touch to an otherwise non-scale subject.

Air vents along the sides of the fuselage are exhaust vents for air coming in through the cowl to cool the motor and ESC. Close examination of the fuselage showed a channel which ran underneath the wings and out to the rear of the model. Given the long development time of the Explorer, these are clearly not for show.

There's certainly no shortage of hardware and accessories. There is, in fact, extra hardware supplied with most FMS models:

I was surprised to see analog servos throughout the model in contrast to the metal geared digital units in the warbirds, but these later proved to work smoothly and center well. I for one would not mind seeing this model upgraded with those digitals at some point.

For those interested in upgrading, Diamond Hobby sells FMS 9g metal geared servos at a very affordable $9.99 each.

FMS claims an assembly time of about an hour, so let's get this party started.


Landing Gear

The landing gear assembly is first called for, but not before a quick check of the manual's contents. It's clear this particular manual didn't benefit from the marvelous rewriting by Diamond Hobby and RCInformer done on behalf of their 980mm high performance warbirds given the language and some errors I'd discover down the road a bit.

Installation is easy enough. The assembly simply slides into its slot beneath the fuselage, the plastic fairing plate goes atop the slot and the fairing is then attached with four 1.7x10mm screws. Simplifying the task of figuring out which screw size was which were labels on each of the hardware bags signifying what was inside.

Tabs on the strut covers correspond to notches in the fuselage's mounting plate. I made the mistake of trying to snug the screws which held one of the covers to the strut and I wound up putting a slight crack in one of them. That would be an experiment I would not repeat with the other cover.


This is where some of the manual's errors would become apparent.

Tail assembly begins with sliding the left stabilizer half in place. The photo shows installation of the right half.

Once in place, the carbon fiber spar is inserted followed by the left half - which shows up as the right half in the photo.

Step four instructs the assembler to "fully sit the rudder in place." The rudder is already in place; it's molded as part of the fuselage.

Step five then shows how to secure the "rudder" - which in this case are the stabilizer halves - with tiny 1.7x5mm screws from the bag marked "elevator."

There are some larger screws in the bag which accompany those little screws; the size isn't given on the bag. Those are the proper screws. Although the manual doesn't point this out, there are overlapping holes in the interlocking elevator tubes which are clearly intended for one of the 1.7x5mm screws. This is the same method used to more positively join the elevator halves as used on the FMS P-47D I'd reviewed prior to the Explorer.

Even without the screw, FMS's keyed interlock is one heck of an idea. As with their 980mm warbird series, the interlock assures the most accurate alignment of the elevator halves possible.


The upper wing is as easy to install as it can be. It slides into place atop the fuselage and is secured with two 3x25mm machine screws. One of the inserts may have had some glue in the threads since one of the screws was hard to insert. I removed the wing, chased the threads with one of the screws and the problem was solved.

The lower wing is double reinforced with two fiberglass spar tubes. The wing halves are installed like those on most models with a two-piece wing. In go the tubes in one half, in go the halves themselves with care needed to guide the aileron servo leads into the battery compartment. A Y-harness is provided to electronically connect the aileron servos, but they can be assigned to different channels if one's radio supports that kind of setup.

Two 3x60mm screws attach the front of the wing and two 3x50mm screws attach the rear. FMS provides spares which is a really nice insurance policy should one of these odd-sized screws be left at the flying field.

Problem: At this point, the aileron control horns and pushrods are not yet installed. Since doing so with the wings detached would be far easier, I bound the receiver with the Airtronics SD-10GS transmitter to center the servos and set to work.

FMS uses heavy-duty ball links on this and their warbird models. I can say from experience that these links do their job well, giving an enhanced feeling of control and accuracy. Snap-on clevises with short lengths of fuel tubing which serve as safety retainers attach the pushrod to the servo arm.

Here's what the rudder setup looked like once completed:

Once the pushrods were in place, on went the wing. Like the top wing, there was some glue contamination of the threads within the fuselage. I was able to seat the screws with a #2 phillips screwdriver, but I plan to chase those threads with a 3mm tap very soon and I recommend others do the same.

Radio Installation

Plugging the servo leads into the receiver, mounting the receiver with some hook-and-loop tape and routing the antenna leads is all there is to completing the radio installation. I fired up the model to check the servos and motor operation and all was fine. I electronically centered the rudder and elevator servos and installed the pushrods in the same manner as those on the ailerons. The rudder needed its control horn to be installed, but the elevator already had a horn as an integral part of the elevator interlock.

I jumped ahead and installed the vortex generators at each wingtip. They're painted to match the wings and the painted areas line up well. A small tube of foam glue is provided, but I'm a big fan of Beacon Foam-Tac and I used some to mount the generators.


It took sometime with the online manual to set end point adjustments and exponential, but once I figured out how to do so, it didn't take a lot of time for me to set up the throws at the recommended rates.

Recommended high/low throws are 16mm 60% expo/12mm 30% expo for the ailerons, 18mm 50% expo/12mm 25% expo for the elevator and 35mm 50% expo/25mm 25% expo for the rudder. Since the SD-10GS has assignable three-position switches bristling from the case, I set up some intermediate throws roughly halfway between the high and low settings.

All that was left was to install the prop and its three-piece spinner. The prop does a pretty good imitation of an APC electric propeller right down to the shaft diameter inserts. One is needed to fit the prop in place.

The spinner cone is also the retaining nut, but since it's plastic, it requires tightening by hand. A small drop of Loctite blue thread locking compound is a really easy way to insure that the cone doesn't spin off in flight. I did the same thing with the P-47G and that spinner has stayed in place throughout a number of flights.

Strapping in the battery and checking the CG at 90 - 95mm behind the LE of the wing are all that stand between firing up the Explorer and aerobatic fun!

Here are a couple of looks under the canopy. Plenty of room is on tap for installing the receiver:


I'd planned on getting video of the Explorer on a beautiful Sunday morning at the Coachella Valley Radio Control Club, my usual venue for most maiden flights and video shoots.

Videographer George Muir had to leave early and he was gone by the time I'd arrived. I made the best of the situation by snapping a few beauty shots before getting ready to fly.

There's lots of room for the receiver as I'd pointed out, but only just enough room in the battery compartment for the battery. The Predator pack is a bit larger than my other 2200mAh 3S packs, but not enough to keep it from fitting.

To further conserve room, I connected the battery and inserted it with the power leads facing toward the front of the plane. This reduced the amount of wiring directly under the canopy. The Explorer seemed to balance tail heavy, but a check of the recommended 90 - 95mm CG point with a borrowed ruler showed it to be right where it should be.

The low power setting on the SD-10GS is a simple menu item; no pressing multiple buttons or pulling switches while powering up. With the range check complete, it was takeoff time.

Ground handling, even in a slight breeze, was excellent. I lined up the Explorer on the center line and fed in some throttle.

The headwind caused some tail wagging, so back I went to try again. With more throttle, off she went, but not without some protesting from the landing gear. The struts are not particularly stiff, so even though the wheels rolled freely, there was still some considerable vibration and chatter in the assembly.

Trim was off quite a bit; the model wanted to roll right and pitch forward. Even with the lack of proper trim, it was immediately apparent that the Explorer was something special. Tracking was laser straight as compensated by the sticks and with excellent speed.

Since I was still unfamiliar with the radio, I decided to land before attempting to trim. Between the upper wing, the vortex generators and all-around light wing loading, the Explorer practically floated in for a perfect three-pointer.

I trimmed the ailerons and elevator, taxied back out to the runway and tried again.

Much better, although the trim still wasn't quite right. Now that I knew where the trim tabs were without having to look, it only took a few moments to get the Explorer flying practically hands off.

Now is where some fun could begin.

On low rates, the recommended expo and control surface throws make for one sweet handling ride. There's still plenty of throw for basic loops and rolls. I did some barrel rolls both with and without rudder input and the Explorer rolled beautifully. Same with some nice, large loops all backed with plenty of reserve power on tap. Most of the maneuvers were at half to three-quarters throttle with nearly unlimited vertical climb available at full throttle.

FMS's claim that this model was a year in development is no ad hype. This was an amazing aircraft and that development showed.

And to think I was still on low rates.

Down came the Explorer for another simulator-perfect landing, out came the Predator battery and in went a fresh one. I kicked everything into the medium rates and went up once more, landing gear happily chattering once more.

This is where things started to get interesting with much faster rolls, more accurate loops and some really stable knife edge flight. I wouldn't normally wring out a new review subject the way I did without rolling video, but I simply couldn't help myself. I even managed to pull off a darn good Cuban Eight on a plane I'd only flown for the first time mere minutes before. Not bad at all, especially when one considers that the control throw and exponential settings were random.

Rather than press my luck, I decided to land and to wait for the video shoot before going into high rates.

When that day arrived, I was ready at the Coachella Valley Radio Control club with club videographer/historian George Muir. I wanted to keep it simple for George, so I once again flew the Explorer on low rates.

If there's one thing that model does well, is glide. The wing loading is so light that it simply wants to float as evidenced by my attempts to pull of a smooth landing.

What I really wanted to do was to fly at the high rates and George was kind enough to offer his assistance via a second video.

Now we were talking.

High rates sometimes equal twitchy response, but this was not the case. If anything, the Explorer flew with even greater accuracy and smoothness than before. The biggest difference I saw was in knife edge flight. The rudder and elevator had gobs of authority and it even felt as if a knife edge loop were possible, although I didn't try it.

Individual pilots may wish to adjust the recommended throw settings per personal preference, but I'll state for the record that the FMS recommendations are darn near perfect.

Aerobatics and Special Flight Performance

Briefly, this model is capable of any and all maneuvers as might be required for F3A competition. I've never flown pattern, but there's talk of doing an event over at the club. If it happens, I'll be armed for bear.

As a sport flyer, the Explorer is an excellent choice with terrific speed and that laser-sharp tracking and response.

Is This For a Beginner?

FMS makes a number of beginner planes and Diamond Hobby can hook one up with no problem. This is a model which calls for intermediate to advanced flying skills. It's easy to fly for someone comfortable with an aerobatic model, but like any model of this type, there's no self-correcting or self-righting built into the design.

Flight Video and Photo Gallery

RCInformer and Diamond Hobby demonstrate the Explorer's capabilities in this detailed video:

FMS / DIAMOND HOBBY F3A EXPLORER Full Review & Demo By: RCINFORMER (12 min 45 sec)

I had a terrific time flying this model as well:

FMS F3A Explorer PNP from Diamond Hobby (2 min 31 sec)


If the models which have been coming forth from FMS, Diamond Hobby and are any indication, the future is indeed bright for model aviation. The FMS F3A Explorer has the goods for real competition as well as just-for-fun flying on a Saturday morning. This is one of the nicest flying models I've ever had the privilege of reviewing and it gets a hearty two thumbs up. Sport flyers and competitors alike, your plane is here.

My thanks go once more to Jim Ogorek of Diamond Hobby for offering this model and battery for review. Special thanks go to Mike Greenshields at Global Hobby Distributors for providing their amazing new Airtronics SD-10GS radio; that rig is going to see a lot of use in future reviews.

Angela Haglund and Jim T. Graham keep things together here at the authors' forum of and they do it, as always, for our audience.

My personal thanks to you in the audience for stopping by! Enjoy your stay at

Pluses and Minuses

Pluses include:

  • Outstanding flight characteristics
  • Light wing loading
  • That upper wing is more than just show
  • Ball links equal slop-free control
  • Beautifully made
  • Assembles quickly
  • Bagged and marked hardware speed assembly
  • Spare hardware is provided for repairs and maintenance
  • Parts and technical support come from a US-based company
  • The pilot bust adds a bit of scale detail to an otherwise non-scale subject
  • Uses popular 2200mAh batteries
  • The year's worth of design is readily apparent

As for the few minuses:

  • The manual hasn't received the excellent Diamond Hobby and RCInformer rewrite
  • Color scheme and graphics are a matter of taste, but they make orientation in flight a snap
  • Landing gear tends to chatter while the model is rolling, even on pavement
Last edited by DismayingObservation; Feb 09, 2015 at 03:16 PM..
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Mar 02, 2015, 08:29 PM
Chef Pilot: Planes vs Butter
ChinoDiablo's Avatar
If she flies as good she looks then she's a steal at $169 delivered.
Hell... that's the same price as an E-Flite UMX Carbon Cub!
Mar 02, 2015, 09:09 PM
Pronoun trouble...
DismayingObservation's Avatar
Thread OP
Originally Posted by ChinoDiablo
If she flies as good she looks then she's a steal at $169 delivered.
Hell... that's the same price as an E-Flite UMX Carbon Cub!
The flight characteristics are simply phenomenal. We've had a long run of crummy weather which is finally supposed to be clearing starting tomorrow.

That said, I have batteries charged and ready to go the moment I can get that plane in the car and back out to the field. I'd charged them up the other day and by the time I'd gotten to the field, up came the wind.

FMS is doing some incredible work thanks to a lot of input from a lot of folks and it shows.

I can't say enough nice things about this model. Really.
Mar 02, 2015, 09:34 PM
Chef Pilot: Planes vs Butter
ChinoDiablo's Avatar
I would think a 12x6 prop or even a 13x6.5 would be a good match for a plane of this size.
Have you done any watt tests or is that outside of your jurisdiction?
Mar 02, 2015, 10:26 PM
Registered User
I would not use threadlock on plastic, it often makes it brittle and will not cure properly. Use CA or similar if needed.
Mar 02, 2015, 10:41 PM
Pronoun trouble...
DismayingObservation's Avatar
Thread OP
Originally Posted by ChinoDiablo
I would think a 12x6 prop or even a 13x6.5 would be a good match for a plane of this size.
Have you done any watt tests or is that outside of your jurisdiction?
You know, I was going to and I forgot. I have an Astro Flight Super Whattmeter for just such an occasion, so I'll happily run a test at the field and post the results here.

Re. the thread locking compound: The spinner has a brass insert and the prop shaft is aluminum. I just went back and read my comment and I clearly didn't indicate that. I'd have likely swapped out the spinner had it been all plastic with no insert. What I meant was that there were no holes through which to place a tool.

I wouldn't have used the Loctite had the spinner's threads been plastic.

Don't ask me how I know that.
Last edited by DismayingObservation; Mar 02, 2015 at 10:53 PM.
Mar 03, 2015, 09:12 AM
AMA 97737
ltc's Avatar
This plane is a smaller version of their F3A Olympus plane, which also got good reviews.
Mar 03, 2015, 07:42 PM
Registered User
Thanks for a great review. I really like this plane due to it running on 3S 2200mah batteries. I have tried to search as much about the plane as I can, the trim issue is a repeating problem I hear about. The bigger brother Olympus seems to be much more true out of the box.
Mar 03, 2015, 08:24 PM
Pronoun trouble...
DismayingObservation's Avatar
Thread OP
Originally Posted by Bmoe
Thanks for a great review. I really like this plane due to it running on 3S 2200mah batteries. I have tried to search as much about the plane as I can, the trim issue is a repeating problem I hear about. The bigger brother Olympus seems to be much more true out of the box.
Thanks for the nice comment!

Most ARFs tend to need a bit of tweaking during the first flight or two, but now that my sample is dialed in, it flies beautifully.

If you're considering one of your own, contact Diamond Hobby ASAP. They're a joy to work with.
Mar 04, 2015, 05:22 PM
Fly Low - Hit Hard
Red Flyer's Avatar
It is oddly beautiful in its purposeful design.

I like it,

Mar 04, 2015, 09:18 PM
Fox 1
RocketRobin's Avatar
Originally Posted by Red Flyer
It is oddly beautiful in its purposeful design.

I like it,

As does the dung beetle.

Last edited by RocketRobin; Mar 04, 2015 at 11:42 PM.
Mar 04, 2015, 10:28 PM
Fly Low - Hit Hard
Red Flyer's Avatar
^ LoL

Mar 04, 2015, 11:40 PM
Fox 1
RocketRobin's Avatar
I'm not really one to talk, my new sport plane is a Mini Contender.
Basically, it looks like it was designed by Roger Ramjet, from the 1960s cartoon show. However, to my gnat sized brain it looks tres chic.

Mar 07, 2015, 07:03 PM
Electrons were young...
What kind of flight times like with the 2200 pack? I see the review video from Dymond uses a 2600 pack. Have they changed the recommended pack?
Mar 07, 2015, 11:56 PM
Pronoun trouble...
DismayingObservation's Avatar
Thread OP
Interestingly, the specs originally called for an 1800. Diamond is recommending a 2200 - 2600 pack. I've been getting in excess of six minutes per flight; I run out of concentration before the Explorer runs out of energy.

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