Silent-Ranger Electric Helicopter

In a nutshell:

Mechanics: "Heim" base

Gear ratio: 1:9.8

Side panels:

"Vario" (lightweight version)

Head and swashplate: Aluminum, custom-made for weight reduction

Shafts: hollow or bored out

Drive: “Geist” 90/2956

Regulator: “Sommerauer” 75 Ah

Batteries: 28 Sanyo 1700 mAh

RPM: approx. 1,300

Cell: custom-made Kevlar cell by Walter Hiller, Volkertshausen, Germany

Internal components: Balsa plywood with “Zack” glued in, partially carbon-reinforced

Windows: Hand-formed for weight reduction

Finish: 2-component lacquer with 3-M film

Leaves: Sitar

Spinner: Thinned-out multiplex

Weights:

Gearbox and motor: 900 g

Head and swashplate: 350 g

Batteries: 1540 g

Blades 335 g

Servos: 100 g

Receiver 40 g

Receiver battery 40 g

ESC 60 g

Tail rotor 100 g

Fuselage (unfinished) 370 g

Internal components and skids 250 g

Gyro 80 g

Finish: 45 g

Discs 30 g

Miscellaneous 60 g

Total 4,300 g

Its hover performance is excellent. This is likely due to the low center of gravity caused by the drive batteries.

The model is surprisingly fast. Light aerobatic maneuvers (turns) and vertical climbs are possible without any problems, but they consume a lot of power. All in all, a fairly brisk flying style is possible,

quite comparable to that of a combustion engine.

The motor is controlled in the usual manner via throttle preselection and follow-through. Although, technically speaking, the direct-drive controller offers better efficiency, the conventional method has proven to be superior, as it prevents a drop in rotor

during abrupt pitch increases.

Unfortunately, the hoped-for reduction in power consumption—and thus longer flight times—did not materialize during the test flight. Presumably, the theoretical savings are offset by higher power demand during climb and recovery maneuvers. Thus, flight times currently range, depending on the expected

flight profile, between 4 and just over 5 minutes.

At the moment, the electric helicopter seems to be more of a device for tinkerers and specialists. Nevertheless, I could imagine that with further refinement of the powertrain (i.e., longer runtime), electric helicopters will become

at our airfields in the foreseeable future.

If you have any questions, please feel free to contact me at

Tel. CH 01/821 31 13 or 01/821 06 24. Gerd Schweidler