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Sep 15, 2013, 02:37 PM
build like there is no 2moz
wallis_100's Avatar
Build Log

Modified Ivan Pettigrew Minicat


Hello Everyone.
Having totalled my favourite airplane last year (Ivan Pettigrew Twin Otter) and being determined to build a flying boat, i have decided that for next years BIMBO event (hopefully if all goes to plan) i will build a slightly tweaked Ivan Pettigre Mini Cat (PBY5A catalina)

The tweaks will be as follows:
1- Full brushless and Lipo set up (rather then brushed set up it was designed for- should save weight which will help with mod 4)
2- Differential steering (as opposed to water rudder)
3- More scale deeper V section, to allow for smoother landings, and better rougher water performance (less bounce!)
4- The important, and likely time consuming one- I will be builidng in a set of 'Scale' retracts, (this is where the extra weight will likey end up- If i'm even with Ivans original weight, i'll be happy)

I'm going to tweak the front end slightly to allow the bomb aimers window, and the blisters on the rear fuselage.

It will likely be a bit of a slow start (work is getting in the way atm ) but it hopefully wont take all year!

So pull up a pew and enjoy the view...
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Sep 16, 2013, 11:18 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Looking forward to it Scott, and "subbed" as they say
Sep 16, 2013, 05:54 PM
Owner - Flying Models
Sounds like a great one Scott, can't wait to see it progress.

Thayer
Sep 19, 2013, 04:34 PM
build like there is no 2moz
wallis_100's Avatar

First wood


Well, havng sent 2 days pondering over the retract ideas, i finally got started.
The first bit of the build will be the fuselage, and speciafically bulkheads G and F, with the supporting structure in between to mount the A frames for the retracts, and the retract drive in between. Then the rest of the Fuselage will follow (Especially the ever so complicated retractable, steerable (i wonder if this is really necessary with differential throttle - could i just let it castor>) nose wheel, and its 'watertight' doors

First part, is the lower and 2 sides of Bulkhead G, the support structure/back fo watertight bay will be set on the inside edge of the 2 sides. as per the pic
Sep 20, 2013, 01:04 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Castoring is good Scott, I have three models, two tailwheels and one nosewheel and all work well. The little Twin Otter has differential throttles and a castoring nosewheel and works a treat.
Sep 20, 2013, 01:33 AM
71% of the world is runway . .
Bart83's Avatar
Nice to see another lightweight flyingboat build in progress.


Cheers,

Bart
Sep 22, 2013, 03:33 PM
build like there is no 2moz
wallis_100's Avatar
Cheers Mike/Bart,

More progress. Got G anf F framed up, and the lower cross mounts in place (dry fit)
Next up is to manufacture the arms, and dry fit those.
Sep 23, 2013, 03:20 PM
build like there is no 2moz
wallis_100's Avatar

Retracting bits


Made a start on the A frames...
Need to sort out how to do the narrow ends (the first attempt snapped)

Mde from 3mm brass tube (pivot rods) and 4mm brass tube (Actual arms)
the 4mm section will also form the attachment pivots on the Oleo legs, and probably the lock stay
Sep 23, 2013, 03:42 PM
Jack of all master of none
splinterz25's Avatar
Wallis... nice work Just a tip:
If you fill the brass tube w/ candle wax before you bend it and let it cool it will help keep the shape of the tube when bending w/ less crimping and there for your tubing will be stronger.

Bruce
Sep 24, 2013, 12:35 AM
build like there is no 2moz
wallis_100's Avatar

Thanks


Bruce,

Cheers for the tip, i will try that on the next two (if it works i have sufficinet spare material to remake the inner hinges)

Scott
Sep 24, 2013, 07:44 AM
Jack of all master of none
splinterz25's Avatar
Quote:
Originally Posted by wallis_100
Bruce,

Cheers for the tip, i will try that on the next two (if it works i have sufficinet spare material to remake the inner hinges)

Scott
Scott I didn't say it but you should then melt out the wax once you've
achieved your bends.

Bruce
Sep 26, 2013, 04:12 PM
build like there is no 2moz
wallis_100's Avatar

A Frames


Got the 4 main A frames dry assembled (including outer pivot bush)
Next job is to work on the spring struts, and then do a dry asssembly in Formers F and G.
Once i've got the Oleo sorted, and the A frmaes mounted, its onto the folding over centre lock/drive stay

Then the rest of the fuselage
Sep 29, 2013, 02:42 PM
build like there is no 2moz
wallis_100's Avatar

Working out the Oleo


Got the A frames mounted up (on one side)
moked up the fully extended oleo (mounting positions only)
The wheel will transit from vertical, to vertical, and clear the bottom fuselage stringer (hopefully)
Even at full compression of the Oleo (10-15mm) should still give 25mm ground clearance
Sep 29, 2013, 02:44 PM
Slip the surly bonds...
Sopwith Mike's Avatar
Very neat Scott. How do you plan to do the waterproofing?
Sep 29, 2013, 02:52 PM
71% of the world is runway . .
Bart83's Avatar
These retracts are so cool , i got to do an amphibian in the future.

Cheers,

Bart


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