The Peregrine drone is an autonomous aerial assault vehicle. Once dispatched to target locations, it can fly in a low-power mode at ultra-high altitudes for months at a time. When it receives the order to strike, it initiates a dive and exceeds the speed of sound several times over before impacting its target. Its low profile makes it generally difficult to detect, but combined with its extremely low-power output when 'orbiting' its target and its ridiculous dive speeds, the only reasonable chance of detecting the Peregrine is if one is already monitoring their upper airspace keenly. On the rare occasions the drones have been detected, it was once the drone had already commenced its dive.
Save for maneuvering flaps, and holes for sensors and the engine, the shell of the Peregrine is a single piece of carbon fibre composite presenting a flat underside and a curved, cylindrical canopy housing the vehicles nuclear scramjet engine and weapon payload.
Ramjet engines work by taking in atmospheric gas as the vehicle flies, compressing and igniting it internally, before exhausting it backwards for added thrust. The faster a ramjet vehicle travels, the more gas it can take in, the more thrust it can output, in a self-perpetuating process.
In the case of the Peregrine, a bottleneck in the engine compresses the gas, while the heat of a nuclear fission reactor heats it up. Because a ramjet engine cannot function at a standstill, the Peregrine requires an assisted launch, either off the back of another aircraft, or from an appropriate launch platform.
The Peregrine can carry virtually any payload light and small enough to fit into it an not compromise detectability. The Peregrine, due to its low-powered orbit patrol, is often deployed where it would be impossible or infeasible to deploy traditional missiles or bombing craft. It's greatest strength is its ability to strike a target within a minute of their detection, so it is usually deployed to take care of targets that are rarely out in the open, and when they spent little time exposed, such as a terrorist leader moving around an occupied city.