PBY Cat Plans? Airfoil/rib plans? - RC Groups
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Mar 24, 2010, 06:39 PM
Frozen Flyer
moes's Avatar

PBY Cat Plans? Airfoil/rib plans?

Hi everyone

I've just started looking around for plans for a PBY Catalina build.

I'm thinking about doing a scratch build shooting for 80" wingspan with electric motors since I've got good access to a few lakes within walking distance and plenty of space to fly.

I've built a few wooden sailplanes from kits, but I've got some good building experience with other balsa/ ply airplane kits and good general understanding of basic airplane design.

I'm wondering if the best way to start a scratch build like this would be to find some plans and try to scale them (as best as possible) up to the size I want, I was thinking that It might be easier to use a Sailplane kit for the wings (spar and ribs, and tail feathers) and mod them to the correct proportions / strength required for the plane, then just build the fuse out of play/ balsa/ glass ect...and then build some nacelles and floats and all other miscellaneous parts.

This would help cut the building time so I wouldn't have to cut ribs by hand and I think would just help speed up the process...

So has anyone else done this? using a kit for wings/ tails parts etc.. ?

I'm just kind of brainstorming right now... thanks for any input/ suggestions!!
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Mar 25, 2010, 12:26 PM
Always Ready!
warhead_71's Avatar
Ivan Pettigrew has PBY plans in several wingspans, as well as Uncle Willies has some I believe. I have also seen plans on Ebay... might be the same thing Uncle Willie sells.
Mar 25, 2010, 12:36 PM
build like there is no 2moz
wallis_100's Avatar

I can HIGHLY reccommend Ivan Pettigrew's catalina, he does 2 sizes.
I have the plan for the smaller one, and its next on my build list when i graduate.
I have has Twin otter, and it is beautiful to fly.

Else draw one u yourself, most planes are not too hard to do, and as the centre section is parrallel chord (easy to cut all the rib blanks and sand them together.) the outer section os only lightly tapered, so again blank sanding, should make it easy..

anyway, have fun, and make sure you put plenty of pics up

Mar 25, 2010, 12:37 PM
Always Ready!
warhead_71's Avatar
Last edited by warhead_71; Mar 25, 2010 at 12:49 PM.
Mar 25, 2010, 04:23 PM
Frozen Flyer
moes's Avatar
Mar 26, 2010, 06:51 PM
Registered User
Slider388's Avatar
As already mentioned, I highly recommend the ivan pettigrew plans.
Mar 30, 2010, 01:30 PM
Frozen Flyer
moes's Avatar
Hey guys,

thanks for the info!

Well I've started the PBY Cat build, and working on the fuse right now, but a few questions, I'm going to be at about a 82" wing span, shooting for 4.5lbs flying weight with twin motors and LIPo battery.

What i'm not very knowledgeable in the electric motors area, after asking around my LHS, they suggested either 370 or 400 size motors. And 6" 2 blade prop, but I was thinking for going with a 3 blade prop to keep it as scale as possible. In that case they recommended a 5-6" prop. Does this seem right? I was thinking of using a 3C lipo with plenty of capacity, I'm not looking for tons of power just enough to take off in a reasonable distance and do sport flying.

Mar 30, 2010, 02:08 PM
Always Ready!
warhead_71's Avatar
Ivan's minicat? A 5-6" prop seems really small and un-scale. Here is what I found:


Here are the specs of the “Mini-Cat PBY-5 Catalina flying boat for Speed 400 motors.
Scale 1:15.
Span 83 in.
Wing area 835 sq.in.
Length 52 in.
Airfoil Selig 7055.
Weight with eight CP-1700 SCR nicads is 64 oz.
Wing loading 11 oz/sq.ft.

Other details: Two GWS geared motors “E” series with 3.4:1 reduction wired parallel driving GWS 9x7 three blade props. Static current is 18 amps, 9 amps to each motor. Average flight time is 15 minutes. Flies 20 minutes on nine 3,000 mAH NiNH cells. Retractable tip floats. Ivan says the “Mini-Cat” is to a pond what a Park Flyer is to a “Park,” so he reckons it qualifies as a “Pond Flyer” !
Mar 30, 2010, 02:48 PM
Always Ready!
warhead_71's Avatar
On 3S, you might try the cheap TP2409-18 motor and 25A ESC with a GWS 10x6x3 or 9x7x3 prop. Should give you plenty of power at 2/3 throttle to ROW then cruise at half throttle.

Prop-test specs here:
Mar 30, 2010, 07:52 PM
Registered User
cracksmeup's Avatar

ivans solent

I am building ivans 480 solent with99 inch wing span and i am going to use 4-480 jamera brushed motors 4-mpi jet gear boxes and 2-3cell 3200 packs swinging 4-10x6 four bladed props. Hey moes get us some pictures of your build. joe
Last edited by cracksmeup; Mar 30, 2010 at 07:57 PM.
Mar 31, 2010, 03:03 AM
build like there is no 2moz
wallis_100's Avatar

that is looking good
really makes me want to start my next IP plane

Mar 31, 2010, 10:43 AM
Registered User
cracksmeup's Avatar


Thanks scott i have been plugging away since nov but i have long ways to go. lol joe
Mar 31, 2010, 07:47 PM
Frozen Flyer
moes's Avatar

2 days in...

Hey nice build there Joe! damn that things going to be a beast!

Well here is where i'm at, i'm about two days in, (I build after work so I get 2-3 hours a day if i'm lucky) and i'm kinda slow right now coming off a cold, but I digress...

So I bought some Mirco-light ply 1/8 X 24" x 48" it seems to a 3 layer balsa ply that is very light and easy to cut with a hacksaw and sand...and seems strong enough for the bulkheads/ fuse keel. I plan on framing the fuse as light as possible and then glass everything...trying to stay light as possible here...

I cut the bulkheads from the full scale plans I got to get the shape, and made some stensles (sp?) out of paper to draw on the ply.

cut the keel last night and sanded, now tonight I plan on start notching the bulkheads to fit the keel notches i'll make and start hollowing out the bulkheads...fun stuff! here are some pics. l
Apr 01, 2010, 07:24 AM
build like there is no 2moz
wallis_100's Avatar

looking good,

the rounded flare on the bottom of the hull will be a pain to do, unless you plank it, you could cheat, and replace it with 2 straight lines, so you have effectivly a sloped up centre, with flat outer bits (makes the hulls plane nicer, and sit more level too)

light ply should be more then enough, Ivans minicat, are balsa frames, skinned in 1/16th balsa, with some glass on the bottom.

ONE key thing: make sure your pylon is strong enough , and add hard points for the struts, so they can take their share too.


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