Although the K-2 has an excellent gliding angle, this is not of great importance. Its ability to decend vertically permits the operator to fly at high altitude to the very edge of his landing place, select the exact spot upon which he will land and glide down to it at a very steep angle if he so chooses, and to correct or alter that angle in conformance with weather conditions and to land deliberately with ample time for observation details

Vertical landings are considered more or less as stunt or emergency landings, Normal Autogiro landing involves gliding to the earth at an angle of about 45 degrees, followed by the use of the rotor system as an air brake to reduce speed to approximately ten or twelve miles per hour so that the use of brakes in landing at this speed brings the craft to a stop usually in about its own length. The speeds mentioned here refer to speed in still air, so that it can be seen that one can make a normal landing, for instance against a ten-mile wind, with no forward speed relative to the ground.

The K-2 is a two-seater, where the passenger and driver sit side by side as in an automobile. A dual control system simplifies flying instructions in this ship. The cockpit of the Autogiro is about as wide as the front seat of the average automobile. It is so cowled in that one is well-protected from the wind and conversation can be carried on.

Although Kellett Autogiro follows very closely the fundamental Cierva Theory, the result of much development work is seen in the many items of the structure. For instance, the undercarriage and fixed wings are supported entirely by steel struts, without the use of any external wires. Also the wheels are set twelve feet apart and are provided with long travel oleo shock absorber struts, which cushion the landing forces so that even vertical landings may be made.

The fuselage frame of the Kellett K-2 is built entirely of chrome-molybdenum steel tubing welded together as a unit. Although the fuselage resembles a conventional airplane, on close inspection it is found to differ quite radically, for the loading of an Autogiro fuselage in flight, as well as in landing conditions is quite different from that of an airplane.

A triangular structure projects from the lower part of the fuselage to carry the hinge points of the very wide tread undercarriage. This structure also gives a very stiff fuselage in spite of the wide cockpit. In making vertical landings it is obviously essential that the shock absorber action of the wheels be vertical for if the wheels were to spread as in an airplane the side loading on the tires would be too great. The low hinge point on the Keller Autogiro permits the use of a tubular strut construction through out without wires and stays.

The fixed wing of the K-2 is of larger dimension than ordinarily seen on Autogiros, though it follows very closely the fundamental Cierva Autogiro Theory. In taking a certain portion of the total load of the craft in the high speed condition, this wing serves as a controlling factor in the operation of the rotor system.

There must be a nice degree of relationship between this fixed wing and the rotor system, for it can be seen that at extremely slow speeds, or in vertical descent, with no forward speed, the rotor is carrying all of the load, but as the speed of forward motion increases, the fixed wing carries an increasing portion of the load, thus permitting the rotor speed to remain constant at all times.

The wing of the K-2 is built up of box spars with wood ribs, fabric covered. The upturned wing tips provide excellent lateral stability and automatically bank the ship at the proper angle when the rudder is used, making the operation of the ailerons practically unnecessary except for the corrections of rough air conditions. In fact, the chief utility of the ailerons is usually at exremely low forward speeds. It is impossible to get a prolonged sideslip in the K-2. The ailerons are the frise type and are operated by push-pull rods.

Each rotor blade (or rotating wing) is built around a tubular spar of large diameter chrome-molybdenum seamless steel tube, heat treated to 180,000 pounds tensile strength per square inch. The symmetrical airfoil section is maintained by the use of approximately fifty plywood ribs, each of which is riveted to a chrome molybdenum steel collar, which in turn is pinned to the spar. This collar fits the tube so tightly that a special tool is used to put the collar on. The leading edge is formed of plywood and the blade completely covered with fabric. The trailing edge is of stainless steel. An interesting K-2 device is the means wherby the rotor clutch is automatically disengaged immediately before take-off.

The K-2 rotor pylon is unique in Autogiro design, in that the large diameter front member carries all of the starting and braking torque and most of the lift but no side load. It has been designed for an ample factor of safety for such loads and is hinged and pinned at its lower end to a fuselage structure built for that purpose. The Kellett pylon is a completely pin-ended structure so designed that the stresses and loads are distributed between the individual members in such a way that each carries a certain share of the stress and is prevented from overload.

The landing gear has a tread 12 feet wide and the oleo struts have ten inches of action. This long travel oleo combined with the use of 10 inch low pressure tires absorbes all shocks of landing. Incidentally, it is extremely difficult to bounce an Autogiro on landing. This is due to the fact that the Autogiro rotor has considerable lift at the time of contact with the ground. At the moment of contact, the load is taken from the rotor, which then flattens out and materially reduces its angle of incidence. Even when the Autogiro is making a vertical or almost vertial landing, the weight of the ship is transferred slowly from the rotor system to the undercarriage.

The pneumatic-tired, roller-bearing tail wheel is also equipped with a long travel oleo strut, so that when tail first landings are made, there is no tendency for the tail to bounce and all landing shocks are taken up before reaching the fuselage.

Control is by conventional stick and rudder pedal system, the Frise ailerons being operated by push-pull rods and the elevator and rudder by direct cables. At the left of the cockpit are found two interlocking levers, one of which controls the rotor clutch and the other the rotor brake. Throttle is on the instrument board. Rudder pedals operate the wheel brakes either together or independently. A crank in the center of the cockpit is used for equalizing the loads on the elevator, for although practically all the variable loading in the K-2 is carried close to the center of gravity, some adjustment is necessary to maintain perfect trim. This is done by spring loading the elevator. Possible failure of the spring in no way impairs the proper functioning of the elevator control.

Standard instruments as follows are included: compass, air speed indicator, altimeter, motor tachometer, rotor tachometer, oil pressure and temperature gauges. Heywood air starter for the motor and engine-drive clutch starter for the rotor are provided. 6.50 by 10 tires with brakes are on the undercarriage wheels and a 10 inch by 3 inch pneumatic tire is on the tail.

The vertical fin, rudder, elevator and stablizer are all of thick section, streamline form and the horizontal surfaces are of high aspect ratio. It will be noted that the stablizer does not have great area due to the fact that the rotor system in an Autogiro serves to a very great extent as a stablizer in all directions. This is due to the fact that the Autogiro has very high inherent stability which actually increases as the forward speed decreases. The fixed stablizer serves far more to increase the efficiency of the elevators as control surfaces than as a stblizing surface.