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Oct 18, 2015, 10:34 AM
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D-Rock's Avatar
Build Log

Fun Scale 60” Grumman Bearcat


Hi all. I wanted to share my latest design/build- a 60” Bearcat. The design has been lingering in my queue for some time now and after working on several “finishing” projects, I was really getting the bug to actually “build” again. This design is a continuation of my “Fun Scale” series in that it is designed with exacting outlines, but features a friendlier flying airfoil, and an “old school” free flight stringer look. The result is expected to be an accurate looking model of the full size, but with a lower wing loading for gentler flying.

It seems we all at some point have/had an ARF- and many have personally some strong thoughts one way or the other on what their impact has had on the hobby- specifically on the building aspect of the hobby. I do not want to fan any flames on the subject, but started out on this project to try and get the best of both worlds. By that, I mean to use a lot of “on the market” hardware/accessories from various ARFs to compliment this build. The power plant will be slightly larger on the Bearcat (Power 60) than on my Hurricane design. The reason for this larger power-plant is the full size Bearcat’s propeller diameter is nearly 1/3 of its total wingspan! The proper propeller and ground stance “look” is one I personally find important when looking to make a convincing model; and I am able to borrow from the ARFs for this. This model’s propeller will feature the 18” diameter one used on FMS’s 1700mm P-47/Corsair and the wheels/struts will also be from the 1700 mm P-47- the same Power 60 power plant is also used. These are widely available and should not break the bank. The retractable tail wheel on the Bearcat comes from another FMS model- the 1400mm Hellcat. Though not from ARFs, the dummy engine and canopy are Sparky’s Park Flyer Plastics http://parkflyerplastics.com/cart/ . In keeping with the “look” of the model on the ground, I decided to keep the scale length of struts. The Bearcat had a unique feature in that the struts fold onto each other. For a small model this would complicate things, so I moved the gear rotation point further out onto the wing. The distance is hardly noticeable to the eye in this size and actually should make ground handling a little easier since it widened the track a bit. Well that’s enough talk about the design and plan, let’s get to some actual building!

D-Rock
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Oct 18, 2015, 10:39 AM
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D-Rock's Avatar
Charlie at Manzano Laser Works http://www.manzanolaser.com/ cut the parts for the prototype. Their work is fantastic- excellent cutting and good wood selection. The main wood types used are 1/8” balsa for the formers, 1/8” lite ply for more structurally important areas, and 3/16” stringers on the fuse. There are some 1/8” Basswood stringers on the wing as well as some 1/16” sheeting.
My previous Fun Scale designs have had the “half shell” fuse (build left then right); for the Bearcat and its unique shape, I chose to build top and bottom. The fuse is built right over the board with the separation line for top and bottom splitting down the cord line of the airfoil. The horizontal of the full-size blends into the fuse, and the vertical into the horizontal. To simplify this on the model, the horizontal is built first, covered, and mounted while the fuse it is still under construction. The vertical is then completed with the horizontal in place.
This model features an airfoiled horizontal and there are several ribs used. These plug into the horizontal leading and trailing edge. The leading and trailing edges have tabs on their bottom to ensure alignment- these are removed after assembly. The 3 trailing edge parts are glued together and pinned to the board. Next the ribs are set in place and finally the leading edge is dry fit to ensure all items match the plans. Once aligned, all are glued. A 1/8” stringer is added to the top- I used spruce/basswood, but hard balsa would have sufficed. Once the assembly was dry, it was removed from the board and the bottom stringer added. The tips are made from several laminations and added to the ends of the horizontal.
The elevators have quite a few pieces- the ribs are already shaped instead of just blanks; helping to reduce sanding time. These “tab” into a leading edge- I found it easier to dry fit these vertically and then slide the trailing edge in. Once the assembly was dry fitted, it was placed back on the board- using 1/4 thick shims for the trailing edge. Once aligned, all was glued. The horizontal and elevator halves were sanded to shape. Next it was on to the fuselage.

D-Rock
Oct 18, 2015, 10:44 AM
Senile Member
Lnagel's Avatar
Go D-Rock. A great subject for your design style.

Larry
Oct 18, 2015, 11:02 AM
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E-Challenged's Avatar
You could decorate the Bearcat easily to look like the early Blue Angels version. Watch the torque etc., with big prop.
Last edited by E-Challenged; Oct 18, 2015 at 11:10 AM.
Oct 18, 2015, 01:57 PM
The Junk Man
I always thought the Bearcat was ugly as sin with that stubby look and disproportionately sized odd rudder... but I love it anyway.

After I get done with some Golden Age stuff the Bearcat is (again, built several over the years) on my list, but a much smaller one than yours.

Tom
Oct 18, 2015, 02:42 PM
killickb
killickb's Avatar
Looks like another must build for the future assuming you and Manzano get it released. Still flying the Hurricane though it will be going in for a recover shortly .
Will be following this thread with great expectations.
Oct 18, 2015, 05:23 PM
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D-Rock's Avatar
Thanks for joining in fellas

The Fuse is built in sub sections and then all added together. The horizontal mounting plates- inner and outers- are added between F-8 and F-9 and the assembly is then pinned to the board. The horizontal is then test fitted to ensure alignment and fit. The firewall and battery box are all interconnected into F-2. These parts are glued together first before being added to the rest of the fuse. The wing mounting plates are made from 4 laminations of 1/8” lite ply and are glued in place on F-6 with tabs. The center wing saddle is then slid into F-6 and also F-3. This assembly is pinned to the table, and the firewall/battery box is glued into slots on F-3. Formers F-4, IP, and F-5 are also slide into place and glued once aligned. Formers F-1 and F-7 have been pinned to the table and the first couple of 3/16” square stringers are added, starting with the top/center stringer first. The wing saddle outers are added along with additional stringers. More stingers were added- HMPO needed to have cuts added to accept the stringers and also requires a little trimming on the bottom for a stringer. The hatch mounting plate upper is added at this time and the remaining stringers as well.

The center sections of the horizontal- top and bottom- were “in-filled” with scrap balsa to allow for better surface area for gluing and the covering. The horizontal and parts of the vertical were test fit and then the entire fuse was given a light sanding. With horizontal set aside for the moment, 1/8” square stringers were added between F-9 and F-10 to help create the separation point between the fuse and the vertical.

The horizontal and elevators were hinged and a U connector wire was bent to shape and added to connect the 2 elevator halves. The horizontal and elevators were covered, but the hinges were not glued in yet- this will happen after the fuse is finished and covered.

D-Rock
Oct 18, 2015, 05:41 PM
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Steve Merrill's Avatar
One of my favorite planes this is a 1/12 scale
Oct 18, 2015, 07:10 PM
Senile Member
Lnagel's Avatar
Magnificent D. Now that is a way to construct a stick fuselage.

Larry
Oct 18, 2015, 10:29 PM
Scale Builder
Outstanding Derek! The Bearcat, along with all the other piston engine 'cats from Grumman, is a personal favorite. I will definitely be looking forward to seeing it out at the field. You can "shoot down" my Zero again when you get the Bearcat going! Speaking of which, hope to see you at the OEAF event next weekend.

PS - Do I see the beginnings of a Thai Air Force paint scheme or is the silver just a base for some other paint job? Personally I like some of the civilian Bearcat schemes, particularly the one used by Grumman field rep Roger Kahn to travel around the country on behalf of the company. Nice way to travel!

Oct 19, 2015, 05:19 AM
Registered User
Yoyocafe's Avatar
Looking great, D-Rock! I'll be following your build!

Joe
Oct 19, 2015, 01:18 PM
Pro Hoarder
turbonut's Avatar
Hard to imagine being paid to fly one around and promote the company....Talking about a cool job
Oct 19, 2015, 03:13 PM
Wanted for breaking Ohm's Law
Dennis Sumner's Avatar
Here's another great civilian scheme.

Bill and Corky Fornof's Bearcats.
Oct 19, 2015, 05:28 PM
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raipe's Avatar
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Oct 19, 2015, 09:15 PM
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D-Rock's Avatar
Thanks for the kind words and support fellas! I was originally planning on doing a Navy paint scheme, but I am surprised at how many civil liveries there are! Cruising across the states in Bearcat must have been a rough job lol.

The build has been moving pretty fast thus far, I was able to frame up the top half of the fuse in one day and the horizontal was done after dinner one night.

D-Rock


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