This text will be of interest both to the technically minded and historians. Although Mr Erickson -- who was the chief test pilot for the B-2 helicopter -- refers to the B-2 helicopter, all of the information is relevant to today's Brantly B-2B.

We are posting this data for all who enjoy historically original designs.

Rotor

"The most outstanding feature of the Model B-2 is the three-bladed all metal main rotor which employs two sets of flapping hinges with lag hinges which are coincident with the outboard flapping hinges at approximately 40% of the blade radius. The inboard blade has a symmetrical section with a 29% thickness ratio and an effective chord of 8.84 inches. It is set at an angle of incidence which is 4 degrees greater than the outboard blade which has a modified NACA 0012 section with an 8 inch chord. The inboard flapping hinge is offset a distance of 2.67 inches from the hub, thereby providing a large hub moment with cyclic control movement giving excellent control response and a relatively large c.g. travel."

"This method of construction is designed to provide complete freedom of motion of the outboard blade sections which experience practically all of the aerodynamic forces of lift and drag. Thus, the outer blade sections, which are subjected to large oscillating forces, are allowed to assume positions more compatible with such forces without inducing bending moments across the outboard hinges. These hinges are supported by the steel tube members of the inboard blade sections which are designed to withstand the inplane bending moments without developing stresses above the fatigue strength of the material. The inboard ends of the steel support tubes are inter-connected from blade to blade by the triangular "tie-plates", so that oscillatory forces tend to counteract themselves within the rotor system without being introduced into the drive system or the controls and fuselage."

Tail Rotor Gear Box

"It will be noted from a side view of the Model B-2 that the new intermediate gear box is at the lowest point in the tail rotor drive system; thus, it makes a convenient oil sump for the system. The main tail rotor shaft is hollow and is housed in a tube extending the length of the tail section with bearing supports provided at approximately 18 inch intervals. It is lubricated by means of a fixed interval worm pump in the intermediate gear box."

"As the shaft rotates, oil is forced from the gear box forward through the drive shaft and allowed to drain back through the bearings to the  gear box in the space between the shaft and its housing. The tail rotor extension shaft is also hollow with a similar stationary worm gear to pump oil from the intermediate gear box up through the shaft passage provided by the space between the shaft and its housing. A vent for the system is provided near the top of the tail rotor gear box. "

Landing Gear

"Each of the four shock absorbers consists of an oleo damper in series with a synthetic rubber disk which limits its travel. The damper is extended by the weight of the skids and incorporates a flapper valve to eliminate resistance so that the gear will drop freely. This valve closes during compression of the oleo with the oil flow being governed by a conventional metering pin."