Park Pattern 200 (oz14861)

About this Plan

Park Pattern 200. Radio control park pattern/sport model. Wingspan 33 in, wing area 200 sq in, for electric power with AXI 2212-34 motor.

Direct submission to Outerzone.

Note this plan is a free download from the FlyRC site at http://www.flyrc.com/bob-aberles-park-pattern/ where there is a full build log and lots of excellent pics.

Quote: "Park Pattern, by Bob Aberle.

BACKGROUND: Over the past half dozen years many new planes and equipment have been introduced into our hobby. Lighter weight electric power systems (motors and batteries) have made it possible to reduce the typical size of our RC model aircraft. Four, five and six-pound aircraft have become less common, while less than one-pound (16 ounces) aircraft is more commonplace today.

The term PARK FLYER has become one of our most important classes of models. Along with that a new maneuver program known as 3D now promotes a lot of close-in flying with considerable emphasis placed on hovering type maneuvers. Many of our younger modelers have taken to this new type aircraft, which requires considerable flying skills. But considering this amount of progress I thought I might combine a little of this new RC technology with some of our old ways of enjoying our hobby.

THE THEME: My thoughts took me to the popular RC pattern flying from years back involving typically 6 pound aircraft powered by .60 glow engines, like the KWIK-FLY, KAOS, TAURUS, etc. Keeping those memories in mind - why not try a park flyer size/weight, electric powered RC model that concentrates more on standard pattern maneuvers rather than hovering (E-3D) maneuvers? This resulting 'Park-Pattern' design tends to give you just that - a little of the old along with a little of the new!

ABOUT THIS DESIGN: My basic idea was to come up with a somewhat conventional looking design with about 200 square inches of wing area and an estimated total weight of 16 ounces (8 ounces for all of the equipment and another 8 ounces for the aircraft). I wanted a plane that was easy to build and easy to fly under most conditions.

Many of us fly from rough fields or grass fields that don’t get cut that often. A low wing aircraft configuration would have been desirable, but not practical. Low wing planes are much harder to grip and hand launch. So for that reason I chose more of a shoulder wing configuration, like the Goldberg Falocon-56 and Senior Falcon. But as you will see on the plans, I raised up the stab level to be slightly above the wing position. The airfoil in this case is the more conservative NACA 2412, which is semi-symmetrical, not fully symmetrical.

I also wanted plenty of extra power and ended up with something like 100 watts input power operating from a 3 cell 1350 mAh Li-Poly battery pack. The resulting 102 watts/pound power loading easily produced vertical climb capability.

The tail dragger configuration works out easier. The vertical fin and rudder are quite large to assist in knife edge flying. Since I had a new sophisticated RC system at my disposal (the Hitec AURORA 9 channel spread spectrum radio) I decided on separate aileron servos so that I might add the flaperon feature later on.

CONSTRUCTION: I started with the wing. Since this airfoil does not have a flat bottom, the building sequence is a little different. I made up two wing rib templates out of 1/16 plywood. Each template has two 1/8 inch diameter holes drilled through it. I made up about 10 oversized pieces of 1/16 inch balsa as wing rib blanks. Two long screws were passed through a template, then through the balsa blanks and finally through the other template. A nut placed on each screw held the 'sandwich' together while I carved the stack into 10 ribs. You can even mark the spar and leading edge cut-outs while the ribs are held together. When separated you have an accurate set of ribs. Repeat this process and cut out the other 10 ribs.

Now you can take two 36 inch lengths of 1/8 diameter wire and insert them through all the holes drilled in the ribs. Space the ribs out and elevate the two wires so that the ribs are suspended over the full size plans. After doing this add the leading and trailing edges and the top spar. Remove the two jig wires, flip over the assembly and add the bottom spar. With this simple technique you should have a perfectly accurate wing structure.

The two wing panels were joined with a slight amount of dihedral, just to make the wing look flat but not drooping. One plywood wing brace is all that is necessary. Two boxes were built on the wing bottom, just out from the fuselage location to accept the two (separate) aileron servos. The ailerons were cut from 1/4 x 1 inch trailing edge stock. Note that the wing tips are flat, but I employed a plywood insert skid at each tip to protect the ailerons.

The fuselage is all balsa sheet, with just cross pieces, no formers except for the plywood firewall. I used a set of builders plywood triangles, available from Aero Craft Ltd, to help align the fuselage sides when placed over the fuselage top plan view. Towards the rear I fashioned a support out of scrap balsa to hold the entire fuselage level while the cross pieces were added. Note that there are some balsa doublers used under the wing location and forward in the battery compartment. A top hatch cover was used so that the battery pack could be easily removed for charging purposes without having to touch the wing.

Rubber bands are used to hold the wing down. But you could easily eliminate them in favor of a set of dowels and nylon screws. The end of the fuselage is left open so that the elevator control rod can pass directly out to the elevator control horn.

On the inside of the fuselage I added 1/64 plywood doublers in the area of the landing gear wire. This provides a stronger surface to which you can epoxy the landing gear strut into position. The stab and elevators were made from 3/32 inch medium balsa, while the vertical fin and rudder was 1/16 balsa. Note that cross grained inserts were added to prevent these surfaces from warping. Also a length of 1/16 x 1/4 spruce runs from the vertical fin down to the bottom of the fuselage. This strengthens the attachment of the fin. Some triangular shaped balsa was placed at the fin/fuselage joint.

POWER SYSTEM: The motor selected was the Hobby Lobby/AXI 2212-34, which can easily produce 100 watts of input power. The motor weighs 2.2 ounces. A Castle Creations Thunderbird-18 amp ESC weighs only 0.6 ounce. A three cell EnerLand 1350 mAh Li-Poly battery pack weighed 3.76 ounces. Using the voltage of three cells the motor current, while swinging an APC 9 X 7E prop, was just under 9 amps."

Update 13/10/2023: Added article PDF, thanks to theshadow.

Supplementary file notes

Article.

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