Chicken Hawk, 3ch RC biplane

I set my target AUW of 453.6 grams, or 16 ounces, for the Chicken Hawk according to a build article I read on the February issue of Model Aviation. The article was written by Bob Benjamin and described his impressions of the Chicken Hawk kit available from Retro RC. By sticking to the original plans posted on Outerzone I managed to achieve an AUW of 416 grams or 14.7 ounces. This weight gives might give a bit of a margin to use slightly higher capacity LiPo batteries. The power plant I am using includes an E-MAX CF2822 1200Kv motor, with a 30A ESC (slightly over-sized), driving an 8x6 propeller. The measured power draw is just over 9 Amps, which yields about 52 Watts. The overall power to weight ratio is between 57 Watts/Lb, which seems more than sufficient to drive the Chicken Hawk. Wing loading is 8.95 ounces per square foot, and Cubic Wing Load is 7.0. I have a similar weight and wing span foam plane with the same power plant, which also gives me a good idea of the expected fight ch

Fuselage The fuselage received two coats of Sanding Sealer with light sanding using a 400 grit paper before each coat . After the first two coats I applied the orange Silk Span trim patterns. I wet the orange Silk Span with water from a spray bottle, positioned it carefully, and removed any trapped air bubbles. Once satisfied, I applied Sanding Sealer to the orange Silk Span to fix it in place. When dry, I ran another light sanding of the entire fuselage and applied the final coat of Sealer. Battery compartment cover. I added a "CH"emblem on the right side of the fuselage made out of black iron-on covering. I printed a template with the size and font I wanted and cut the lettering with a sharp hobby knife. Wings I followed the test covering process I did on the balsa frame and covered the wings with clear (white) Silk Span. Once the edges where dry, I followed with light sanding and a coat of Sealer. I added the orange color trim following the 1963 patterns. Just like the fus

I decided to stay with the old-school theme and cover the Chicken Hawk with silk span. The last time I used silk span was probably around 35 years ago on a glider I built. The process I remember involved attaching the dry silk span sheet to the wing surface with lacquer thinner, then wetting the sheet to get it to stretch, and finally applying a couple of Sanding Sealer coats to the covered wing. We used Sanding Sealer instead of Dope, probably because of price and availability. After searching the web and checking with my fellow club members, I found that the recommended process is not much different today then it was a few decades ago. I started with a test frame in order to get some practice and make sure I have the right materials. In general, the recommended process involves applying a few coats of Dope on the balsa surface you want to cover, then attaching and stretching a sheet of silk span. The sheet is fixed into place with some more Dope or thinner. There are many variations

The landing gear and battery hatch are two areas that I modified from the original plans. The wider opening will accommodate a wider 1,500 mAh LiPo for a longer flight duration. The landing gear is made out of 2mm steel wire and is taller than the original aluminium frame. The landing gear is lighter and provides clearance for the 8x6 prop that I intend to use.  I formed the battery hatch out of 3/8" stock and glued three magnets with matching washers on the fuselage for attachment. Ornamental pilot head-rest Skid, 1/16" ply horn, and elevator push rod visible The complete fuselage (without two servos) weighs 124 grams (about 4.4 oz), which is much below my original goal of 220 grams. Adding the two wings yields about 200 grams total before lacquer and covering. My estimated AUW will be about 395 grams with a 1,500mAh battery and 240 grams with an 800mAh battery.

The fuselage is taking shape and by following the advice in the build article I turn my attention to the tail section and build the stabilizers, elevator and rudder. I used 3/32" balsa instead of 1/16" for a more sturdy structure. 3/"32 balsa was still too thin for nylon hinges and for a retro look I went with hinges made out of white silk span, which is an idea I got at the hobby shop while chatting with the owner about my plans for the silk span I purchased. Once again, my magnet board was useful in achieving a perfect right angle between the horizontal stab and the fin. Once dry, I fitted the stabilizers onto the fuselage, with the top-wing pylon, and completes the top sheeting. here are some close views or the work so far after some basic sanding. And the overall look of the model with dry fitted wings. The fuselage weighs about 77 grams, which is so far much below my target. I still need to add the battery compartment cover with magnets, landing gear, and push-rods.

Before setting out to build the fuselage I decided to do some planning and lots of reading. My Chicken Hawk will be powered by an electric motor so I had to make some changes to the fuselage in order to accommodate a battery, an ESC, and a different motor form factor. The plans also depict a control mechanism that I will replace with two 9 gram servos and a receiver. Because I don't have access to the plans of the modern kit, my only option was to closely examine picture on various build logs and articles, as well as draft some ideas before starting to cut any balsa. My modifications were simple. I replaced the bottom covering between former F1 and F3 with a hatch and an opening for the battery. I also refashioned former F2 with a larger opening. Moving former F1 forward by 3/4" gave me more space for the electronics and eliminated the need for any extension to the motor backing. Heeding the advice of others, I was very careful marking and cutting the fuselage sides. I used tw