A99 UAV EFI Engine System (Preliminary)

Description (Preliminary)

The A99 is currently under development. Its inline three-cylinder architecture is based off Cobra Aero’s A33 combustion system platform. It features precision liquid cooling, sequential multi-point fuel injection, tuned intake and exhaust, and a direct drive generator.

A99 inline triple liquid cooled engine

  • High power to weight
  • Low acoustic signature
  • Cowls much tighter than typical boxer twin
  • 3D-printed aluminum head, cylinder, crankcase and exhaust improves engine repeatability
  • Hardware, electronics and software all designed specifically for UAS applications
  • Primary and secondary shaking forces are inherently balanced
  • Fires every 120 deg. Higher frequency torque impulses provide for relatively smooth operation
  • Separate crankcases for each cylinder for improved mixture control and decreased cycle-to-cycle variability
  • Ideal for spark ignited heavy fuel due to small cylinder bores and liquid cooling

Specifications (Preliminary)

Engine Type: Liquid-cooled 2-stroke inline triple
Displacement: 99 cc (6.0 ci)
Mass: 3.65 kg (8 lbs) (Includes core engine, exhaust, ECU, fuel pump, injectors, ignition, generator, harnesses)
Fuel Delivery: Fuel injection at 3 bar (gasoline 50:1 premix; (heavy fuel in development))
Power Output: 6.0 kW (8.1 HP) at 8200 RPM
Fuel Consumption: 500 g/kW-hr (0.82 lbs/HP-hr) at cruise
Generator output: 400W (700W intermittent duty cycle)

The engine package includes

  • Power4Flight IntelliJect ECU
  • Currawong self-priming fuel pump
  • All required EFI sensors and wire harnessing
    • CHT, MAT and Fuel pressure
    • Baro and MAP
    • CDI module
    • Fuel pressure accumulator
  • Induction and exhaust system
  • Electric power generator with start capability
  • Cooling system with active control