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