The Engines

To keep piston velocity low, the engine has a fairly oversquare bore/stroke ratio (98mm / 3,86” x 70mm / 2,75”) in order to keep piston speed low, as well as fairly short con rods. The short rods give higher piston acceleration which helps in effective filling early on the intake stroke. Narrow and light piston/ring components tolerate high acceleration well.

Whilst the company has initially focussed on fixed-wing applications, the engine is ideal for helicopter operation, and can be optimized to provide high power and torque at constant speed as required in rotary-wing applications. The PSRU also is ideally suited to installation in legacy helicopters which use belt drives to the rotors.

Although diesel has certain advantages with regards to fuel consumption and economy, we don’t believe that compression ignition technology is best suited to GA applications.

Among the reasons for this are:

• Poor relationship between torque and power
• If used at high altitudes Jet-A has to be used as it contains an anti-freeze that diesel fuels do not have
• Compression ignition engines have to be heavier to contain higher bearing loads
• Diesel engines have poor power to weight ratios
• Typical harshness of Diesel engines require complex vibration-isolating solutions
• Harsh firing impulses of Compression ignition engines has a negative effect on reduction gearbox and propeller life
• Satisfactory power generation generally requires high turbo boost with related reliability problems
• Diesel fuel weighs more than gasoline
• We can meet the fuel consumption targets by using an efficient gasoline engine

ADEPT engines are installed / or are currently in process of being installed in a variety of aircraft including Lancairs, Velocity’s, and some exciting new aircraft in development.

As an example, a 320HP engine is fitted to the all-composite SA Ravin 500 (a South African designed and manufactured aircraft similar to the Piper Comanche). The combination of the ADEPT engine and the Ravin airframe results in one of the finest GA aircraft in the world, with an operating radius of over 1900NM (3500Km) and a 12-hour endurance capability.

ADEPT is working with several Non Type Certified airframe OEMs as well as a wide range of aircraft builders and owners flying aircraft ranging from Super Cubs, Lancairs, Velocitys, RV-10s, and aircraft used in crop spraying and humanitarian operations. In addition, the engine is ideal for legacy aircraft engine replacements once certification is obtained.

The ADEPT motor utilizes best-practice current engine technology and is therefore extremely economical and reliable. The ADEPT motor offers competitive acquisition costs and affordable operating and maintenance costs.

The engine has been designed with a targeted TBO in excess of 2000 hours. Our TBO projections are being confirmed during our monitored flight programme.

The ADEPT engine is extremely fuel-efficient, and runs on Autogas/Mogas that is generally far less expensive than Avgas. ADEPT engines are also designed for ease of maintenance, and utilize readily available, modern service components, with far lower costs than traditional aviation service parts. Due to the modern design of the engine, service intervals are also extended in relation to traditional aviation engines.

It is a compact design offering high efficiencies, lightweight, low vibration levels and high structural integrity leading to long engine life.

Current technology gasoline engines are most efficient at higher RPM than the RPM range at which the traditional legacy aviation engines usually operate. The ADEPT engine’s average piston speed is lower than that of conventional GA engines due to the optimum bore/stroke ratio used. The low mass of reciprocating parts also reduces engine wear.

The ADEPT PSRU is a robust and thoroughly engineered unit. It is an integral part of the engine structure. The PSRU reduction ratio has been selected to provide low noise and an absence of annoying and dangerous harmonics. Robust gear forms, and the use of a combination of extremely robust roller bearings for radial shaft support, and taper roller bearings for both pusher and tractor thrust loads ensure reliability and durability. The unit also incorporates a gear cush-drive to protect the rest of the engine from prop strikes.