This device is a modified version of McVey

[Princess]

This device is a modified version of McVey or McEvoy’s first motor, adapted to operate as a Poggen or Poggendorff corona motor without brushes, featuring self-starting and unidirectional rotation.
Device Type
A corona motor (also called electrostatic or atmospheric motor) uses high-voltage static electricity to ionize air around sharp electrodes, creating corona discharge that propels an insulated rotor like a glass cylinder.
Historical Context
Johann Christian Poggendorff invented the corona motor around 1869, initially with a glass disk rotor between angled combs for charge transfer. The figure shows an early modification of McVey’s pioneer motor, replacing brushes with corona principles for brushless operation.
Key Design Features
• Central glass cylinder rotor spins freely on an axis between positive (+) and negative (-) terminals.
• Surrounding radial combs or electrodes (slanted for self-starting) spray ions onto the rotor via corona discharge, causing asymmetric attraction/repulsion for unidirectional torque.
• No windings, magnets, or brushes; relies purely on electrostatic forces.[pubs.aip]
Operating Principle
High voltage (tens of kV) across electrodes ionizes air, depositing charge on the insulating rotor surface; opposite charges attract, pulling the rotor toward the next electrode while discharge removes prior charge, sustaining rotation. Slanted combs ensure automatic startup and one-way spin.
Practical Notes
Modern replicas achieve ~0.1 hp at 12,000 RPM with >50% efficiency using plastic rotors and knife-edge electrodes, ideal for high-voltage demos like Van de Graaff generators. Low torque limits power but suits educational vintage electrical exhibits.