A33 UAV Engine System

A33N UAV EFI Engine System Overview

The A33N UAV Engine System is Cobra Aero’s initial entrant in the A33 family of engines. This unit combines high power-to-weight with low acoustic signature in a simple and reliable propulsion module that fits a typical 3W-28i footprint.

  • Passed FAR-33 150 Hour Endurance Profile

Summary Specifications

Engine Type: Air-cooled 2-stroke single
Displacement: 33 cc
Weight: 2.25 kg (5 lbs) (Includes core engine, exhaust, ECU, fuel pump, injector, ignition, generator, harnesses)
Fuel Delivery: Fuel injection at 3 bar
Power Output: 2.3 kW (2.5 HP) at 8000 RPM
Fuel Consumption: 500 g/kW-hr (0.82 lbs/HP-hr) at cruise
Generator output: 250W (500W intermittent duty cycle)

Endurance Report: A33N FAR-33 150 Hour Endurance Test Report 

The A33N Engine will be available in the near future.

A33 EFI UAV Engine

A33 EFI UAV Engine



EFI Engine with Integrated Generator

The A33N engine is an all-new purpose designed UAV engine. It features high quality fully machined crankcases that overcome porosity issues, provide a more precise path for internal fuel/air circulation and incorporate an integrated generator and generator drive system. Other improvements include a new propeller hub design, incorporating a more accurate crank angle sensing system. The ignition system is based on a Desert Aircraft CDI unit with modifications to facilitate control by the ECU. Furthermore, the cylinder ports are fully machined (patent pending) to minimize engine-to-engine power variability. This simplifies fleet management, and it allows a ‘tighter’ fleet ECU calibration for improved performance and fuel economy. The engine also offers a twin plug head, and extra cooling fins which integrate into the cowling for more precise air flow over the cylinder.

Maxon Generator

The A33N UAV engine is equipped with a 3-phase Maxon brushless motor used as a generator. The generator is driven by a toothed belt from the engine output shaft and produces 250 watts (500 watts intermittent) of electrical power.

Exhaust System

The exhaust system used on the A33N both maximizes performance and substantially reduces acoustic signature. It is also lightweight and rebuildable for simple field maintenance.