Peregrine Phoenix
The Peregrine Phoenix microturbine hybrid electric system is a cutting edge power solution for UAVs that boasts a class leading power to weight ratio and unmatched reliability.
What is a Hybrid System?
A hybrid system refers to a method of powering a device that utilizes multiple forms of energy simultaneously or interchangeably. This approach aims to optimize efficiency and performance by integrating different energy sources, such as combining traditional fuels with electrical energy from batteries.
The Peregrine Phoenix is a hybrid system designed for powering Unmanned Aerial Vehicles (UAVs). The process by which it does so is using a combustion engine to turn a generator, which in turn generates electricity to power the UAV.
Why Use a Hybrid System?
Conventional UAVs are powered by electric motors, which get their energy from batteries. The primary issue with batteries is their energy density.
Energy density refers to how much energy can be stored per unit mass, for example, kerosene can store between 42 and 46 megajoules of energy per kilogram of fuel.
Lithium ion batteries on the other hand, like those used in electric cars and some UAVs, have an energy density of less than 1 megajoule per kilogram.
So why do we use batteries instead of fuel if fuel has so much more energy density? Well there are three primary reasons: engine weight, efficiency, and cost.
First, while the fuel is far lighter than the batteries, the engines required to harness the energy in fuel are heavy. This makes them impractical for aviation applications, especially in Vertical Take Off and Landing (VTOL) applications where you need multiple heavy motors.
Secondly there is efficiency; electric systems have the advantage that there is very little loss of power between the battery and the motor. Combustion engines on the other hand struggle to efficiently convert fuel into power efficiently. An electric drivetrain can have efficiencies of over 85%, whereas even the best combustion systems still do less than 50%.
Finally there is cost to consider. Batteries and electric motors are cheap compared to combustion engines (on the scale of UAVs) and don’t require much maintenance. In addition, the proliferation of battery technology into the mainstream means that batteries continue to be inexpensive, whereas combustion engines on the scale of UAVs are still uncommon and therefore are expensive.
So the questions that still need to be answered are: what are the advantages of a hybrid system? What are the disadvantages? And what are we doing differently?
A hybrid system for UAVs still uses electric motors, but it uses a combustion engine to generate the electricity.
The primary advantage of this is that the UAV can maintain the lightweight nature and efficiency of electric motors, but benefit from the superior energy density of fuel, therefore you end up with a far longer flight time than a system with batteries.
However, there is still a combustion engine, so doesn’t that mean that the UAV is heavy? Yes, and that is one of the disadvantages of conventional hybrid systems. These systems require a heavy combustion engine and therefore the engines need to be small so the UAV can lift them. This means that the engine cannot generate as much power as the batteries, limiting payload.
So what are we doing different? We utilize a microturbine engine rather than a reciprocating engine to generate the electricity. A microturbine engine has a far higher power to weight ratio than a reciprocating engine, meaning that it can generate a significant amount more power for a given amount of weight. It can also generate that power in a far higher range of altitudes.
The effect of this is that our system solves the problem of a reduced payload capacity that is typically associated with hybrid systems. The Peregrine Phoenix for example, our prototype hybrid unit, has over double the power to weight of a typical reciprocating hybrid system.
Our systems are powerful, lightweight, and reliable. They benefit from the power of batteries, and the energy density of fuel, making them the perfect solution for any UAV that demands performance and confidence for any mission.