Autogyro Co. of Arizona: Kellett YG-1B autogyro

Model Airplane News, Mar 2002 by Anderson, Richard

FLIGHT TEST

Golden Age wingless wonder

the Kellett YG-1B is the latest addition to the Autogyro Co. of Arizona's growing stable of autogyros. This large, sport-scale, rotary-wing aircraft has a rotor span of 74 inches and is IMAA-- legal. Like the rest of the company's models, the Kellett is a laser-cut kit and shares a common control system with their other autogyros.

This large model has a rotor disc area of nearly 28 square feet and a loading of 4.5 to 5 ounces per square foot, so you'll need a strong .61 2-stroke or .91 4-stroke engine with a simple 4-channel radio to fly it. A high-tourque servo (75-ounce or more) must be used for the rotor tilt contro..

IN THE BOX

The kit comes in standard and deluxe versions (the deluxe kit includes hardware). My kit was well packaged; none of the parts were damaged. It comes with two full-size CAD plan sheets and full-size illustrations of all laser-cut wood sheets and other construction details. All of the hardware is neatly bagged and labeled to help you follow the fully illustrated 58-page construction manual. The well-- written manual contains many building tips along with chapters for preflight and flight instructions, For construction, I used various glues (CA, epoxy and aliphatic wood glue) where appropriate. Some of the conStruction, such as installing the servos, elevator bellcrank and fire wall blind nuts, needs to he accomplished first; it's difficult to finish them later.

FUSELAGE AND STABILIZER CONSTRUCTION

I began construction by assembling the bottom keel, soaking it in warm water and then using the provided shims to bend it to its corfeet shape when pinned to the plan. I allowed the keel to completely dry before gluing the formers to it. I positioned the farmers and the servo tray on the keel and epoxied them into place using 5-minute epoxy, making sure everything was square. I used the supplied jig to correctly position the firewall to attain the proper downthrust. being careful not to tsvist the fuselage, I glued the balsa stringers to the foriners with thick CA to form the basic fuselage shape.

The horizontal stabilizer is a full flying stabilizer with a twist: the flat-bottom airfoil on the left stabilizer is upright and upside-down on the right stabilizer. This is a scale replica of the full-size Kellett's horizontal stabilizer arrangement and proved necessary in the model, as well. After I installed the balsa ribs, I sanded there to an airfoil shape and then joined the stabilizer halves to the fuselage with two steel rods that run through a brass sleeve built into the aft end of the fuselage; they are retained with collars and setscrews. After I installed the stabilizer halves, I connected the elevator pushrods to the servo and set the control throws.

The rudder and sub-fins are balsa cores with ribs glued to both sides of the rudder and to the outboard sides of the sub-fins; they are then sanded to an airfoil shape. I next installed the rudder controlhorn mounting blocks and the balsa leading edge (I.I) on the rudder and fit it to the fuselage; then I connected the rudder pushrod and checked it for proper travel. I next installed the landing-gear-support side plates and lower reinforcement plates and epoxied them into place. I sheeted the forward section of the fuselage with 3 1/16-inch balsa planks; to properly fit between the stringers, the edges of the planks need to be beveled. To make the planks conform more easily to the shape of the fuselage, I soaked them in ammonia before I glued them into place. The landing gear is rather unorthodox; it looks flimsy but is really very strong and resilient. I placed the fuselage upside-down on my workbench and assembled the landing gear on it. I wrapped the joints with copper wire and used silver solder to tie everything together. The result is a very strong landing gear.

When you install the tailwheel assembly, pay attention to the tilt-back angle of the fuselage; the lower the tail sits to the ground, the easier the rotor system will self-- start. I next sheeted the bottom forward section of the fuselage with the precut 2z-inch plywood sheeting. It's difficult to get the plywood to lay correctly on the compound curves, so I cut it into two parts, and this allowed it to conform to the curvature. I used 5-minute epoxy to glue the sheeting into place. I tried to plank the turtle deck with 3/16x3/32-inch balsa sticks, and I found this difficult to do. I decide to substitute 1/16-- inch balsa sheet and sheet the turtle deck in two sections.

ROTOR PYLON ASSEMBLY

The rotor pylon is built as upper and lower halves that have a polypropylene hinge sandwiched between them to allow the upper pylon to pivot left and right. I used 30-minute epoxy to laminate two 1/8-inch plywood plates together. The polypropylene hinge is held in the pylon with small screws and nuts, in case it ever needs to be replaced.

I next installed the upper pylon firewall and the 1/2-inch tri stock and sanded away the excess. Satisfied with the pylon assembly, I trial-fit the rotor pylon assembly to the fuselage; the assembly must fit snugly. It's also important that the rotor pylon fit squarely in the fuselage and be properly aligned fore and aft. Using aliphatic wood glue and tape, I next glued the laser-cut 1/32-inch-plywood front cockpit sheeting to the fuselage. It was a perfect fit.