Kyosho PBY ARF Conversion

By Steve Horney Email: Steve

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* Wingspan: 68.5 in. (1740 mm)
* Wing Area: 573 sq. in. (37 sq. m) listed; my measurements appear closer to 615 sq. in.
* Length: 44.5 in. (1130 mm)
* Flying Weight: 6.5 lb. depending on configuration.
* Wing Loading: 26 oz/sq. ft (based on listed wing area)
* Airfoil: 16% semi-symmetrical Motors: 2x AstroFlight cobalt 05 sport motors
* Props: Two Master Airscrew 7x4
* Cells: 9x SR Batteries, SR Max 2400 mAh cells
* Power Loading: (9V/45A/104 oz) 62 - 64 Watts/lb.
* Radio: Multiplex Cockpit transmitter, Hitec 555 receiver, 2x Hobbico CS-12 micro-servos, 2x Hobbico CS-35 mini servos - later changed from CS-35's to two Hobbico TS-11 micro-servos.
* Speed Control: New Creations 60 Amp BEC controller (would recommend using a receiver pack with this setup instead of BEC)
* Manufacturer: Kyosho
* Available from: Tower Hobbies

Historical Background

Used extensively by both the U.S. Navy and the U.S. Army Air Force in W.W. II, the Consolidated Aircraft PBY Catalina (OA-10 in Army Air Force form) is undoubtedly one of the most recognizable aircraft in the world. Available as both a seaplane and an amphibian, PBY planes and crews rescued a huge number of downed airmen and performed a variety of other missions as well, including reconnaissance and even a bit of torpedo bombing. Even after the war, PBY Catalinas didn't just retire to the airplane bone yards; many continued with other nations and in civilian life as executive transports and hospital planes.

With such an illustrious career, the PBY is a natural for modeling, and even more appealing from the natural aura and mystique surrounding seaplanes. Kyosho has taken this subject and developed it into beautiful, high-quality ARF that greatly assists the modeler in creating his own "personal copy" of the PBY.

The Model

As seen from the kits contents of Kyosho's SQS series PBY Catalina, it is a beautifully built ARF that greatly simplifies the task of constructing this scale warbird.

Opening up the box for Kyosho's Super Quality Series (SQS) PBY Catalina elicits the sort of "oohs" and "aahs" that one would expect of a kit in this price range. This is one impressive looking ARF, with a beautiful fiberglass fuselage, nicely built covered flying surfaces, and a very complete set of accessories that were all nicely grouped and bagged. One thing that strikes you when you first see the PBY is its size; this is one big airplane! Kyosho's ARF construction greatly assists in getting a very striking PBY in the air much more rapidly than a traditional kit, but don't expect to build this one in an hour. There's still plenty of work left to give you that satisfying feeling of having "built it yourself".



The wings on the PBY are divided into three basic units. The center section carries the motors and joins the assembly to the hull, and the two outer panels take care of aileron and tip float duties. Construction of the tip panels was pretty straight forward, other than switching micro servos for the full size servos normally used, but the center section required more extensive modification due to the unique requirements of electric power, namely the wiring! Most of the wing construction information will be summarized in the photos below. I was impressed with the ARF construction overall, but I was somewhat baffled by one thing. Kyosho requires a fair amount of drilling on this plane (and lots of careful measuring for the holes), for everything from wing strut and float stays to the wing mounting holes. I would have expected a kit in this price and quality range to have most of those holes pre-drilled, which could easily be done with a factory jig. This would have greatly reducing the risk of "builder error". The other item I found interesting on my plane was that the aileron servo mount locations were fully "hogged" out with plywood mounts in place, but the glow motor throttle servo wells needed additional cleaning up and the plywood mounts had to be installed. As an electric conversion, this was of no consequence to me, but I found it interesting.

Aileron and Servo Installation

Wing construction begins by joining the ailerons and wing tips to the outer panels.

I opted to use micro-servos instead of the full-size units in order to save weight. This required the addition of a plywood plate on one end to make the servo mount fit. In addition, the servo covers would not fit, so I ended up covering the installation with a high-quality plastic tape (for water protection).

Holes are drilled in the wing for the float and wing strut stays, and then the stays are epoxied in place. It would have been nice if these were pre-drilled, but it isn't too hard. Just be sure to take your time, measure carefully, and keep the drill aligned. (A drill press would be very nice for this work, but I don't have one.)

The wing aileron servo is in place and hooked up to the aileron. Also visible is the servo wire extension coming out of the wing panel. It's a good idea to tape the extensions where they come together to prevent separation of the wiring. (That could be uncomfortable in flight!). Holes are already in place for the wiring, and they're large enough to fit the extensions without having to cut and solder the servo wires, which is a nice touch.

Motor Mounting and Wiring

The photos below show my initial setup using a pair of Velkom 24/10 motors from Hi Country Hobbies . These are superb ferrite motors, but I later switched to AstroFlight cobalt 05's in a weight saving effort.

I used the glow throttle servo hole to facilitate moving the wiring in the channels. The first step here was to drill a 1/4 inch hole from the motor mount into the servo opening to allow the wiring to be drawn through to the motor mount. (I just ran the drill bit through the hole in the circular plywood firewall and straight into the wing.) A thin piece of piano wire taped to the motor wiring works well to pull the wire through the wing and out to the mount. The ends were then tied to keep the wiring from being pulled back into the wing. I kept my wires the same length and installed Anderson Power Pole connectors on the ends, and then joined the connectors to power the motors in series initially. (Join the negative of one side to the positive of the other side, and then orient the remaining two connectors, a positive and negative from opposite motors, to join to the battery.) Later, I rewired the motors in parallel by joining the positive and negative leads from one motor to the respective positive and negative leads of the other motor.

Here are a couple more views of the motors being wired, and the servo and motor wire paths.

For mounting the Velkom 24/10 motors, I opted to use Hobby Lobby International's new aluminum mounts designed for their Jeti motors. This made a nice, clean mounting arrangement.

Interestingly, as you can see in these photos of the Velkom 24/10 motors, I discovered that the motors each had different front end-bells. Apparently, Velkom decided to change the end bells during the time the two motors were manufactured. The motors both ran the same, so it was only an appearance item as far as the plane was concerned. (The new motor may have slightly better cooling, since it has more open area.)

The Velkom motors fit the cowlings perfectly, and looked good, with a pseudo-radial look in my opinion.

Wing Struts and Tip Floats

The wing struts are made from painted dowels that must be cut to length. The ends are drilled for the attachment hooks on either end. The hooks join at the wing and fuselage with stays and are held in place with setscrews. It would be a good idea to apply some WD-40 or grease to the wire hooks and the setscrews, as unprotected they will rust in the water!

As you can see in these photos during wing float construction, wire rods are epoxied into the floats, and then the wire is mounted to the wing attachment points with setscrews. The wires tend to come off at various angles from the floats, and require some pressure to bring them in to fit the stays. This isn't a problem, as it helps hold them in place, but it looks a little odd. It could cause a float to be out of alignment. The wire lengths may need to be cut to keep the floats out of the water when the plane is at rest, but mine were fine in the original length.

Other Items

One item to note was the need to drill the wing mounting boltholes. Again, here's a place where it pays to take your time and measure carefully. I opted to measure and drill the holes from the bottom of the wing. That way I knew the holes on the bottom of the wing would line up with the mounting holes on the fuselage, even if I got a little off as I drilled through the wing.

The cowling installation was easy, but a little strange. The cowlings are three-piece arrangements, with top and bottom clamshell halves for the region behind the firewall (where a fuel tank would normally be installed), and a one-piece cowl to cover the motor installation. This is all well and good, but the recommended method to attach them is to use some of the provided small screws to join the clamshell halves to the wing and the cowl to the firewall. It works well with the cowl (screws go into the firewall), but the clamshell halves are sheeted foam, so there is nothing to hold the screws. To make matters worse, the unthreaded region of the screw under the head is just long enough to pull through the sheeting, thus giving thread engagement only into foam! It will hold somewhat, because of the pull by the plastic parts being curved around holds the screws in shear against the sheeting, but it would probably be smarter to join the upper and lower halves with tape or CA or possibly a silicone glue.


Kyosho laid up a strong, nicely gel-coated, and quite attractive fiberglass fuselage for the PBY. Most of the fuselage work was in the tail installation. Otherwise, the work consisted of drilling the fuselage for the wing strut stays and wing hold-down bolts, and doing a little work on the hatch and servo mount crutch.

Wing Bolt Plate Installation

This was a pretty easy process, other than the need to carefully measure and drill the wing boltholes. The boltholes are drilled oversize in this case, so that a blind nut can be installed from the back side. I used epoxy on the plywood plates, and then held them in place with clamps until the glue cured.

Clamps are used to ensure a good bond during the wing bolt plate installation.

Battery Tray

Kyosho unwittingly provided a great battery tray location with the plywood blocks that are in the fuselage for the landing gear. I wanted to keep things a little lighter, so rather than just cutting out a hefty piece of plywood, I used sandwich construction to build a battery tray out of a light 3/32 balsa core with 1/64 ply sheeting on each side. I originally intended to sheet only one side, but the tray wanted to curl, so I ended up sheeting both sides. The result was both light and stiff. I then covered the tray with some industrial strength Velcro, with the mating side applied to the batteries.

For the battery tray construction, balsa core (3/32") was sheeted on each side with 1/64" ply using aliphatic resin. Strips of Velcro were then applied to the tray. The final photo shows the two 7-cell packs of SR Max 2400's in place. The side-by-side arrangement was used to clear the pushrods, but it also gave more area for the Velcro attachment. I ended up mounting the battery tray over the plywood blocks used for landing gear reinforcement. This made a great battery mount, and the balance came out just right. (Note: This was the initial configuration. In the final configuration, nine cells were used and the batteries were moved to the servo tray for balance. The servos were moved to the tail).

Servo Tray

The servo tray is built from four pieces of plywood. I epoxied the pieces together and held them with rubber bands to cure. Since the hull curves upward, I had to do a little trimming of the bottom of the servo tray to get it to mate somewhat reasonably with the hull. (It was then epoxied in place). I also added a plywood extension to the rear of the servo tray to level it. Some of the additional leveling work came from moving the tray forward from the recommended location to allow installation of the battery support plate. Since I was using smaller servos than the full-sized servos recommended, I added some plywood extension plates to the servo holes to allow proper fit of the CS-35 servos. Weighing only an ounce and generating 55 in-oz of torque, CS-35 servos are very nice units for medium and larger planes. I later changed to mounting micro-servos in the tail and dispensed with the larger servos and long push rods, but I kept the tray as a mount for the receiver and receiver battery. (The speed control was mounted to the upper inside of the fuselage with Velcro.) I wanted to keep things dry from the water that inevitably seems to work its way into a seaplane. The tray also serves as a mounting point for the hook that holds the fuselage hatch rubber band. A final change saw the battery tray used as a receiver mount and the servo tray used for a battery mount (for balance reasons).

The first photo of the servo support assembly shows the support while the epoxy was drying. The second photo shows it with the radio gear in place and before installation in the plane.


The hatch only required gluing the tongue and rubber band hold-down in place. A little fitting was required, but it was pretty simple over all. A large rubber band (supplied) is looped through the hole in the hatch attachment and around the hook mounted to the servo-mounting tray.

The only assembly required for the hatch is to glue the tongue and the rubber band attachment in place.

Here's a photo of the hatch in action, plus a few views of the radio compartment with the batteries and all gear in place. These views show my original "stock" setup with larger servos and long pushrods.

Other Comments

The battery support plate was a little short. It needed a little more length to account for the battery wires. I didn't anticipate the height difference with the servo mount causing interference. This required the use of a Dremel to route out the bulkhead for additional battery clearance. I ran the antenna out the top of the fuselage behind the hatch and through a small hole that I drilled in the top of the fuselage. I then taped it down the length of the fuselage.

During construction, I found that the long pushrods were awkward and heavy. I would recommend switching to sheathed cable if you want to maintain the stock servo positioning. (It is probably a more water resistant setup as well). After hassling with the long pushrods for a while (and one flight), I changed course and installed a pair of Hobbico TS-11 micro-servos in the tail with a couple of servo wire extensions to reach the receiver. This gave short, direct links to the control surfaces and lightened the plane. In addition, it was easier to install than the pushrod setup and didn't interfere with battery mounting.

Mounting the servos in the tail proved rather easy. I simply outlined the servo base with an X-Acto knife (using the pushrod exit holes as a starting point), cut away the section, inserted the servo (the holes gave a good, close fit), drilled the holes for the screws, and screwed the servos right to the fiberglass. The hull is thick enough that it provided a good hold without the need for a back plate. I then cut the ends of the pushrods to the appropriate length and joined them to the servo arm using setscrew style rod connectors.

Here is a view of the micro-servo installation in the tail for the elevator. The rudder servo is on the other side and offset from the elevator servo to prevent mounting interference.

Tail Surfaces

Setting up the tail surfaces on the PBY is a little more challenging than most of the other steps, but it's not hard. I ended up having to open up the stabilizer holes in the fin a little bit to get the stabilizer to fit properly. (Along the way, I learned that it is hard to mark a dark surface with pen or pencil and have it show up!). I also had to create a couple of U-shaped notches behind the stabilizer openings to accommodate the wire elevator joiner. Be sure to install the joiner before installing the stab! Two pieces of balsa, shaped to the contour of the fin, are epoxied into place above and below the stab, after the stabilizer is installed. This helps to hold the fin and stabilizer together properly. These pieces required a little trimming for proper fit, and you'll have to cut the covering off the stabilizer where it's covered by the fin to obtain proper glue joints. Probably the most challenging part of all this is making sure the stabilizer is properly aligned with the wing and perpendicular to the fin. What makes this more challenging than with other planes is the flexibility of the fin sides. They tend to bow out a little without the balsa parts installed. In order to obtain correct measurements, I dry-fitted the balsa pieces, held the fin sides together against the balsa pieces, and made the measurements.

Once the stabilizer is epoxied in place, both elevator halves need to be joined to the stabilizer and to the elevator joiner. Kyosho did a nice job of pre-slotting all the control surfaces for their hinges, making this job easier. However, you still must very carefully drill each half for the joiner and notch out a section of the leading edge of the elevators for the wire. I like the hinges supplied by Kyosho; they're circular, making slot dimensions a little less critical, and they are held in place by wicking CA through the hinge and into the slot. This is very convenient!

The photo on the left shows the stabilizer slots with the wire jointer notch. In the center photo, you can see the stabilizer and wire joiner in place, with the balsa fin supports above and below the center of the stab. On the right, you can see the two elevator halves now joined and drying, with a pair of pens taped to the halves to hold them in alignment. I quickly discarded that method and just used a steel ruler to keep the alignment in check until dry.

Along with figuring out the tail wheel/water rudder setup, installing the fin closeout was a bit of a challenge. A balsa piece is used for the aft edge of the fin, but variations in the fiberglass in the fin and the molding left a fair amount of required trimming to fit the piece. This wasn't hard, but it was a little annoying at times, especially when the pictures don't quite match the setup. I used some black trim tape to cover the balsa closeout after the assembly was dry.

Due to excess fiberglass along the lower aft edges, the fin closeout had to be trimmed quite a bit on the bottom to fit properly.

The water rudder and tail wheel are operated by a wire that extends down from the rudder and through a tube in the bottom of the fuselage. A hole must be drilled for the tube through both sides of the aft end of the fuselage for the tube, which can be a little tricky to keep aligned, since it's so close to the aft end of the fin. Before installation, a washer is soldered to the bottom of the tube. This serves to support the tube and tail wheel, and helps to seal this region from water. The tube/washer assembly is epoxied in place from the bottom of the fuselage. The rudder must be drilled and channeled for the rudder/tail wheel wire, which is then epoxied in place before the fin is installed. Switching between the rudder and the tail wheel is relatively easy and clever. The wire from the rudder sticks straight down from the fuselage. A thick aluminum tube with setscrews at each end then joins either the water rudder or the tail wheel to the rudder wire.

In the photo on the left, a washer is being soldered to the tail wheel/water rudder tube. I drilled a hole in a block of wood the diameter of the tube (and at the depth I wanted), set the tube in place, placed the washer around it, and then soldered it together. The photo in the center shows the tail wheel in place. On the right, you can see the black trim material I used to cover the balsa used for the fin.

Landing Gear

One very nice touch with the PBY is its dual mission capability. While I believe some of the earlier kits were in sea-plane only form, my kit came with landing gear that could be swapped in place of the floats and water rudder, giving me the option of flying from land. Actually, I suppose you could say this plane has tri-mission capability, since it could be flown from the snow as well! At any rate, the landing gear supplied is not scale, but it functions very well and it is easy to install and remove. The main gear is just inserted into tubes already installed in the fuselage and held together with rubber bands. The tail wheel and water rudder interchange by using an aluminum fitting with a hole drilled in each end and a setscrew on each side. One end of the fitting attaches to the wire coming from the rudder, while the other end allows the water rudder or tail wheel to be installed. The one disadvantage I've seen is that the hold is not always the best. I lost one tail wheel while making a takeoff run on some bumpier ground. The holes in the fitting were also drilled at a little bit of an angle, but this wasn't a problem. I just adjusted the angle orientation to the fore and aft direction. If you really want a scale look, Kyosho includes directions on how to build a scale landing gear setup for the PBY.

The photo on the left shows the main landing gear. (The rubber bands shown are not the ones included with the kit.) On the left is a photo of the tail wheel, water rudder, and the fitting that makes it possible to interchange the two.

Power Systems

Initial Power System

This is one of the Velkom 24/10 motors in place on the wing.

My initial intent with the PBY was to see how it would perform with a quality, lower cost power setup. So, thinking along those lines, I decided to go with a couple of Hi Country Hobbies Velkom 24/10 motors, APC 8x6 props, Hobby Lobby GR1171 5mm collet adapters, 14 SR Max 2400 mAh cells from SR Batteries , an AstroFlight 217D ESC, and Hobby Lobby DB001 motor mounts. The Velkom 24/10 motors are about twice the cost of a Speed 600 type motor, but still less than half the cost of a cobalt motor, and they're worth every penny. They're probably the nicest ferrite motors anywhere. The only thing that differentiates these motors from a good cobalt motor is the magnets. Rather than the usual "can" construction of most ferrite motors, these motors feature hardened 5 mm shafts, machined aluminum bell housings (with cooling holes), ball bearings, replaceable brushes, and adjustable timing. I've seen these motors perform on a couple of planes (a sport plane and a sailplane), and I was impressed. They seemed to be just the ticket for the PBY.

My choice of an 8x6 APC prop was based on experience and some of the E-modeling programs. I found that the motors seemed to turn fewer RPMs (10,600) than I was expecting from the modeling programs, but they were still powerful. Based on experience, the 35 amp current draw was reasonable, especially since it was nine amps under the modeling program predictions. I spent some time breaking in the motors when I first installed them, and found that interesting phenomenon that happens with series-wired motors. If one turns easier than the other does, it will run faster while the other one shuts down. I ended up placing a prop on one motor at a time while I ran in the other one under reduced voltage.

My initial decision to use 14 cells was based on a goal of around 60 watts/lb. I didn't intend for the PBY to be a hot aerobat, but a nice seaplane for doing cool looking splash and goes. Assuming a nominal current draw of around 30 amps and a seven-pound airplane, 14 cells appeared to be just about right for my power goal. SR Batteries' 2400mAh cells are well made packs that have enough capacity for some pretty decent flight times, and I had a pair of these seven-cell packs waiting around just for this project, so that's what I used.

I originally picked up the AstroFlight 217D to use on a Kyosho Cessna 180 that I was reviewing (powered by a geared AstroFlight 035), but since the 217D had a 16 cell/35 amp capacity, it also appeared to be a good choice for the PBY. I think I overworked it a little in my initial setup, but it held up well. (I found the shrink-wrap was staring to melt!) I'm sure the long wiring and higher than initially planned currents (35 amps) probably didn't help matters.

Revised Power System

As you will see in the flying section, the initial flight on the PBY was less than spectacular. It took a long run into the wind to get it off the ground, and then it felt very heavy and on the edge of stalling the entire flight, which was following by a rather fast landing to avoid a stall. At that point, I decided that I needed to either increase the power and shed some weight, or give up on this project. This was too nice of a plane to give up on, so I opted for the former. (Additionally, I had a couple of new AstroFlight 05's sitting around that I had initially purchased for this project.) My revisions included going to micro servos in the tail as mentioned previously, plus two AstroFlight sport cobalt 05's, APC 7x6 props, and motor mounts from a couple of Hobbico Cessna 180's. This setup pulls about 30 amps and turns the props at 12,800 RPM. My weight savings wasn't huge, around four to six ounces, but every bit helps. As it turned out, this wasn't enough weight savings, and I ended up rewiring the motors in parallel and going with nine cells and 7x4 props, but I'll get to that in the flying section.

Here is the mounting setup for the AstroFlight cobalt 05's, and a view from the front showing the motors and APC 7x6 props installed.

This is the PBY with the AstroFlight motors in seaplane configuration.

This is the PBY with the AstroFlight motors in land plane configuration.

Final Touches

Not much was left to finish off the PBY, other than adding decals and the observation blisters on the fuselage. I went ahead and painted the framework on the blisters, then tried to install them with silicone glue. The instructions call for screwing and gluing the blisters to the fuselage with epoxy. That seemed like overkill to me. Epoxy would be more than sufficient, and screws would have the potential of leaking water into the hull. I opted to try the silicone so that it wouldn't be as permanent, just in case I didn't like the appearance. As it turned out, the silicone didn't hold well at all, and I ended up removing the blisters. I didn't care for the small mismatch between the paint and the hull anyway, and I like the cleaner appearance without them. That's only my preference, however, as there's nothing wrong with Kyosho's blister windows.

The PBY sits on it "land legs". This is a very pretty airplane! These photos show the plane with the original Velkom 24/10 motors.

Here are the observation windows after I painted in the frames and installed them. I ended up removing the blisters for most of my flight work. I wasn't entirely happy with my paintwork and I like the looks without them. I know they are part of the original character, but I still like the "cleaner look". (...just my own quirk)


From the Land

My original intent was to fly the PBY off the water first, since that's the whole idea behind having a seaplane! I figured that any unexpected "happenings" would be softened by a water impact rather than a land impact. Unfortunately (as you'll see below), I was initially unable to get the PBY to take off the water. Therefore, I installed the landing gear and headed to our club's field. Weighing in at 120 ounces in its initial configuration, I knew the PBY had a heavy wing loading. I was thankful for the relatively long and open grass runway our club enjoys. As it turned out, I needed most of it! My initial take off run was unsuccessful. I was running crosswind (because of the direction of the wind) and only succeeded in eating up a lot of runway before I shut it down. Since the wind was fairly strong, I decided to move towards the end of the runway and try again, this time with the PBY pointed into the wind. (The grass extended far enough to the side, which allowed a takeoff into the wind.) It still took a long run, but the PBY did successfully take to the air, as the photos below prove. She looked very pretty in the sky, but I wasn't very comfortable with the experience. The plane felt very much on edge the whole flight, as if it was ready to fall out of the sky at a moment's notice. There was no backing off the throttle here, and even at full bore, the climb angle was pretty shallow. After making a few rounds over the field, I decided to bring the PBY in while I still had plenty of power. This was one plane that I definitely did not want to land dead stick! I brought the PBY in for a relatively smooth landing, keeping the speed up to prevent the dreaded stall/snap situation that commonly afflicts planes with high wing loadings at slow speeds. It and I survived the experience, but it wasn't something I was looking forward to again! At the initial weight, the PBY was not a pleasant plane to fly. The wing loading was around 30 oz./sq. ft., with a power loading of around 62 watts/lb. This means that I was trying to fly something with the wing loading of a hot-ducted fan on the power loading of a mild trainer, and that is not a recommended combination!

The PBY looks great in the air!

Although my initial outing was less than a rousing success, this plane was too pretty to give up on. Therefore, I went with stage II, and reduce the weight and increase the power. As mentioned earlier in this review, that took place in basically two ways. First, I switched the motors from the Velkom motors to AstroFlight cobalt 05 motors. The AstroFlight motors have more power, but more important to me was the fact that they're at least two ounces lighter per motors. I also changed from two mid-size servos and the long, heavy pushrods, to a pair of micro servos in the tail with much short and lighter rods. This gave me a considerable boost in control accuracy and authority, and it freed up room in the battery compartment. The total weight savings of these two changes was around six ounces. While this was not huge, every bit helped. I opted for APC 7x6 props in this case, since I've had good success in other applications with this setup. The current draw was just a hair under 30 amps, which was right where I wanted it. My initial taxi tests looked hopeful; the plane seemed to accelerate better, but success was not to be. I managed to get the plane airborne, but it just didn't have enough "oomph", and it ended up dropping back to the ground and cartwheeling. I probably should have kept it on the ground longer, but I was running out of room. While not a good thing in and of itself, this incident did prove that this is a tough plane. The only damage was a cracked stabilizer, which was easily fixed. (It's a wood and film covered component.)

At this point, I realized that even with more power, the PBY was not going to be a pleasant flyer, at least at these weight levels. (I could have increased the props to 8x6 or 9x5, which would have resulted in a big bump in current draw.) It would need long takeoff runs, have to be flown relatively fast, and require fairly fast landings. I decided that I needed to shave quite a bit more weight while still keeping the power up. The best option seemed to be to change the configuration and go for ten cells and motors wired in parallel, pulling 40 amps plus, and use a BEC to eliminate the weight of the receiver pack. Playing around with the *Calc programs showed a pair of AstroFlight 15's or a pair of geared AstroFlight 035's would be the best choices, since they could turn some good size props (8 or 9 inch) at the right current levels (20 to 25 amps per motor) with fairly high efficiency. The weight savings of four cells, plus going to slightly lighter 1700 mAh cells, and eliminating the receiver pack would drop the weight to just over 100 ounces, quite a drop off the original 120 ounces. The only was only one question left. Did I still want to make an effort to fly this plane, or should I just give up? I'm too stubborn to give up, and I really do like the looks of the PBY, so the option was clear. I had to try again!

I decided to stick with the AstroFlight 05's (for convenience and cost reasons), but make some changes to the configuration. I wired the motors in series, switched to my New Creations 60 amp controller with BEC, changed to a 10-cell pack of Sanyo 1700 mAh SCR cells, and switched to Master Airscrew 7x4 props. The current draw was now quite high for the battery at nearly 52 amps, but the prop RPM was up there too, at nearly 16,000 RPM. Between the notably lighter weight of 104 ounces (1 lb. lighter than the initial configuration) and added power that was up from 62 watts/lb. to 80 watts/lb, the PBY now felt like it was ready to seriously take to the sky, . As you will see in the Snow Flying section below, I made one more alteration to the configuration before I actually committed to flying it again. My taxi tests were showing some problems with the motors cutting off early, so I backed off the cell count to nine, and went with SR Max 2400mAh cells to get a little more flight time. The current draw was now around 45 amps, and she still had plenty of power, although the power loading was back down to 62 to 64 watts/lb. As it turned out, I didn't make any more land flights, but I did fly it off the snow, and the results were great! Sometimes perseverance pays off.

This plane looks sharp in the air. From the Sea

When I first assembled the PBY (all 120 ounces of it), I was excited to see how it would perform on the water. After all, that's why you get a seaplane, isn't it? Well, my success was rather mixed. I found the PBY handled very well on the water. I had no trouble getting it to go right where I wanted, but I couldn't get it on plane. Every time I tried, a large bow wave developed that flowed right into the props, slowing the whole thing down. I was about to conclude that this plane couldn't be flown off the water without spray rails, but I decided to give it another chance when I rewired it and cut a pound out of the weight. To shorten up a longer story, the weight savings and power increase were just the right medicine to put the "sea" back in this seaplane. I still got a bow wave, but it was much smaller and the PBY was able to power right through it, coming on plane easily and rapidly. It was beautiful to watch it skimming across the top of our subdivision pond. I haven't yet actually flown off the water, due to the cold weather and lack of a convenient lake at the moment (that will come later), but I did get it briefly airborne on our pond, so I can say it will fly nicely off the water, provided you keep the weight down!

The PBY is beautiful and has easy water handling, but can be a challenge to get on step if it is overweight.

From the Snow

I was hoping to have a chance to try the PBY off the snow, but we just weren't having any snow this winter. It seems like a seaplane is ideal for snow flying. The hull rides up on top of the snow nicely, and you don't need skis or floats to make it work. As it turned out, there was a big snowfall near the end of March, right after the beginning of spring! Not being one to complain about the weather, I took advantage of the opportunity to try out the PBY on frozen water, and I was not disappointed. Of course, the biggest reason for the success was that I now had the power system sorted out. The two AstroFlight 05 motors were wired in parallel, turning Master Airscrew 7x4 props, backed up by nine SR Max 2400 cells, and the PBY was now a pound or more lighter (and more powerful). During my taxi tests with ten cells, it showed plenty of power, but my BEC controller, despite being rated for twelve cells and 60 amps, was experiencing some shut downs. I decided to back down the power a bit and ease up on the ESC by going to nine cells. This worked well, but I should have taken the conservative approach and used a receiver pack (as you'll see in a minute).

On the snow, this Catalina tracked straight and true, going airborne after a run of 50 feet or so. Everything was very smooth and majestic, but unlike my first flight from land, the PBY now also felt very controllable, with power to spare. I was really enjoying this! After a couple of circuits, I decided to play it safe and have a little fun with a snow landing by bringing it in early since it was pulling a lot of current. However, here is where I ran into problems. I had been keeping the plane over the snow-covered field all along, just in case the controller shut down, but it seem to be doing fine. Unfortunately, when I went to land, I brought it across the parking lot, cut the power, and suddenly found myself with no control! The PBY was flying wing level, but pitched down at a steeper angle than I wanted for an approach. It bounced hard on the pavement, rebounding back into the air, and then coming to rest on the snow, where I suddenly had control again! It's frustrating to have something like that happen. Things going wrong at the one wrong spot, but sometimes that's how things happen. Actually, the PBY wasn't that badly hurt. This is a very tough bird! It had several cracks in the fuselage and a broken battery tray (formerly the servo tray), but that was about it. Right now, I put it aside, but I am sure it will be repaired in the not too distant future and placed back in service again.

I charged up the battery when I got home and tested it on land. (I should have done that first, but I was trying to get in a flight before sundown.) While running the motors at part throttle settings between 20 and 30 amps, everything seemed to work well for a minute or two, but then it happened. The motors and controls all stopped and froze. A few seconds later, they worked fine again. The ESC seemed hot. I suspect that the combination of high currents, heavy part throttle usage, and long wiring conspired to overheat the controller and shut down the system. Here's where a 270mAh to 350mAh battery pack would have been handy. (It would have weighed about the same as the extra cell I removed when I went to nine cells). Live and learn! At any rate, I was thrilled. I finally found a combination that flew the PBY well. It was a long road, but the end success gave me a good feeling of accomplishment.

Kyosho's PBY looks good on the snow, and flies even better! One big advantage of snow flying is the weight and drag savings of losing the landing gear, rudder, and wing floats. Of course, the best part is that it's just "plane" fun.


Overall, Kyosho's PBY Catalina is a beautiful, well-made plane. I think Kyosho should have pre-drilled many of the components in an ARF of this price and quality, but otherwise it is a fairly easy way to get a great-looking PBY. Flight performance as an electric is highly dependent on the final weight. As an ARF, it's already somewhat heavy, and there's not a lot that can be done to lighten it. Some creativity is required to keep the weight down to near glow levels. Fortunately, it can be done with the batteries and equipment we have today, but don't expect to win any "All-Up/Last Down" contests! I went through several iterations before I got what I considered acceptable performance, but once I did, I found Kyosho's PBY to be a very nice flying airplane, and a real beauty on the land, sea, snow, or sky. This is a very versatile plane, and one that you'll love to show off to the guys. Basically, you'll need to use light components and keep the cell count down to ten sub-C size cells or less. If you keep the weight of this plane under 6 1/2 lbs., with reasonable power (I recommend around 400 watts in.), it will give very nice performance and fly very sweetly.

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