Fun build 5 Guillow's PBY - Page 2 - RC Groups
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May 26, 2012, 02:40 PM
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conrad907's Avatar
Sorry I haven't posted any progress pics recently. I spilled coffee on my laptop keyboard! It had a bad effect. I lost my pictures I was going to post. I am at work this week, but have purchased a new laptop and will post some pics when I fly home.

I have installed the mounts for the tail section, covering is on the tail pieces, the linkages and pushrods for the elevator and rudder are done and installed. The fuselage has just a little sheeting left to do. The nose is on, tip floats with hinged mounts are on.

I am trying very hard to get this in the air by June, but I am embarrassed how slow my build is going. I put so many hours in on it, yet the progress comes slowly. Oh, well, I can honestly say I am hooked on the whole RC thing, wish I would have started this sooner, and wish I would have picked a simpler first build!

I have a pair of Super Tigre 370 motors and one 35 amp ESC. WIll this work for power? I also have a 3s lipo, 11.1 v, 2000mah battery. Will this work? For props 2-5x3.

Next week when I return from the job here, I can post some new pics. The current weight is at about 22.5 ounces with all the electrical gear and rc gear added in. Hope I can stay under 32 ounces, should be able to.
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May 26, 2012, 08:09 PM
It's a Great Day to Fly
LenBFP's Avatar
Hi Conrad,

Your PBY is looking great.

While it is sometimes possible to run two brushless motors from a single ESC, it is not advisable, especially with a waterplane. The ESC senses the position of the stator with relation to the magnets and two motors can confuse it. Sometimes one motor fails to start. I would recommend an ESC for each motor.

The recommended prop size for the Super Tiger 370 is 9". This tells me the KV of the motor is too low to turn a 5" prop at the rpm you will need with a three cell lipo. You might look at the motors others have used with this model. One possibility with this motor might be to run it on a four cell lipo to get the rpm up.

Keep up the fine work,

May 27, 2012, 03:08 PM
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conrad907's Avatar
Thanks for the advice Len. This project is a big learning experience for me every step of the way! If were not for the advice and access to other build threads here, I would have had a very disappointing outcome on this build.

I found some pics on my camera chip, but the plane is actually farther along than these photos show. I will post them anyways.

My question on two ESC's would be, if I used for example, a pair of 15-20 amp ESC's, Would all the input wiring be spliced parallel, with outputs going to the respective motors? Or, do I need to program an extra receiver port, say an aux port to slave to throttle command inputs, and just splice the battery input? Any help for my first attempt is really appreciated.

I will do some more research on the best motor to use, I thought I had a combo that would work, but I am too bogged down in learning other aspects of to learn motor rewinding! Although, I would suppose motor rewinding is another approach to tailoring a motor to a specific plane.

Budget is not my big concern on this build, which is a good thing as I have purchased all manner of building supplies so far just to try different things out, but doing things right is my goal.
Jun 10, 2012, 10:54 AM
The "pro" in procrastination
Steve85's Avatar
Hey Conrad,

The finish on your PBY looks great! You seem to be quite a bit closer to completion than I am with my Lancaster.....

Jun 10, 2012, 08:15 PM
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conrad907's Avatar
Steve, I am trying something for finish on this that seems to be giving me good results. I sand the 1/32 sheeting down as far as I dare, then fill small imperfections with some spot putty. I then put on a coat of West System epoxy and wait until the epoxy cures good, I sand it down as much as possible, then put on another coat. I also sand this coat of epoxy down as much as possible trying not to take it down to wood.
A lite coat of paint covers very well at this point as it does not soak into the sealed grain. The finish is smooth, tough, and has a very metallic appearance to it.
It is a slow very labor intensive approach, but the weight is reasonable and I believe comparable to other approaches.
I have experimented with Doculam, and I don't have the hang of it yet, to my satisfaction, so I am going a different route to see if it will work.
Jun 11, 2012, 01:09 AM
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conrad907's Avatar
I am really stymied with my attempt to find a proper motor. I am considering trying this one:

Type: Brushless outrunner
Size: Replacement for 280/370
Bearings or Bushings: Bearings (One 3.175 x 7.94 x 3.6mm Bearing, and One 3.175 x 9.525 x 3.97mm Bearing)
Recommended Prop Range: 8 x 3.8 to 10 x 4.7
Voltage: 7.2–12
RPM/Volt (Kv): 1360Kv
Resistance (Ri): .10 ohms
Idle Current (Io): 1.00A @ 10V
Shaft Diameter: 3.17mm (1/8 in)
Overall Length: 25mm (1.00 in)
Weight: 45 g (1.6 oz)
Overall Diameter: 28mm (1.10 in)
Diameter: 28 mm (1.1 in)
Length: 25 mm (1 in)
Continuous Current: 12A
Maximum Burst Current: 15A (15 sec)
Cells: 6–10 Ni-Cd/Ni-MH or 2–3S Li-Po
Speed Control: 10–20 amp brushless

This motor was suggested as a possibility in the build threads. I am having a tough time finding a motor ideal for this application. Any thoughts or help on this would be really appreciated.
Jun 11, 2012, 10:20 AM
Mustang Fever

Weigh everything you've built so far, and post the total. If you do that, I'll use Markus Muller's ecalc and come up with a suggestion for you.
Jun 12, 2012, 12:28 AM
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conrad907's Avatar
Thanks Bob, this is something I reallly need help sorting out. I am at a remote work site at the moment, but the last weights I took showed I will come out close to 30 ounces. That was including the two 370 Super Tigre motors, (which I will not be using), a battery, and a 30 amp esc. It is possible my weight may come in a little less, but I am allowing an extra one and a half oz.'s for things I may not have thought of between now and the final assembled build.
Jun 12, 2012, 08:15 AM
Mustang Fever
Conrad: here's the ecalc url, where I got the information:

When I ran this, I used 16 oz as the weight, so as to get figures for a twin:

2- Turnigy Park 300-1080. 6x4 MAS 3 blade counter rotating props.
Single 1000 mAh 3S 20C pack. 2- 10 or 20A brushless ESCs. Total weight of power system approximately 10oz.

Peformance: 11,390 RPM, 42mph, 24oz thrust total. Current 4A each motor, flight time 10+ at mixed throttle.

The motors are found at:

The listing for all of the Zippy 3S packs starts here:

I would not purchase a battery pack until the airplane is finished, with everything installed. During final construction, make sure that a battery pack may be mounted all the way up in the bow. (The Catalinas are very difficult to balance, as they come out way tail heavy.)

The key thing with brushless systems is that the wires between the packs and the ESCs must be kept as short as possible. You'll need to make up long wire sets between the ESCs and the motors.

Near as I've been able to determine, the Eflite and Turnigy motors are identical, built in the same factory, so why pay more for the Eflite?

I have a 46 and a 60 in service, and they are good performers.
Jun 12, 2012, 12:58 PM
Always Ready!
warhead_71's Avatar
Subscribing. Mine is still half-finished and languishing in a box.
Jun 12, 2012, 01:47 PM
Registered User
As a thought.
I use the Hyperion LONG cased 12 mm brushless, diameter motors with a B P Hobbies gearbox & fly the larger Guan Li PBY easily on GWS counter rotating props. Motor & gearboxes are about 1.1 oz each.
Last edited by cyclops2; Jun 12, 2012 at 01:55 PM.
Jun 12, 2012, 02:04 PM
Registered User

Blogs are good !

I have a lot of data charts on my blog page. Frist time I looked at my repeated picture postings.
Some are of the Hyperion motor & gearboxes & props. The better gearbox to use is the B P HOBBIES units. They are Aluminum & really keep the motors cool.
Jun 13, 2012, 01:23 AM
Registered User
conrad907's Avatar
The help on power systems for this plane is greatly appreciated. I think I will go ahead with the direct drive Turnigy motors instead of a gearbox setup for my first plane. I have made sure to keep the bow open for getting the battery as far forward as possible. Consensus from everyone seems to favor the two ESC approach, so that is how I will go also. Your tips on wiring are noted.

Thanks for the info Cyclops on this other power system, but I think I will try the direct drive motors for the maiden.

I am trying to keep weigh to an absolute minimum as I finish up, and hope to finish out closer to 28 oz. finished, but not sure I can get there. I agree about the tail being a little heavy on this model. I cut out as much of the extra balsa as I felt was prudent to do, but Guillow's designed quite an overbuilt set of tailfeathers. In hindsight, laminated hoops and some contest grade balsa ribs would have made it much lighter. But then, they said the plane wasn't a flying model, so....

Warhead, hope you get your PBY out and finish it, it truly is a beautiful kit as it comes together. In hindsight, I had no idea it would be so difficult to build this plane, but I am getting excited now to try and get it done and airborne.
Last edited by conrad907; Jun 13, 2012 at 01:24 AM. Reason: typo

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