The Plan to Boost Drone Batteries With a Teensy Jet Engine - Kirk Warshaw (left), the CEO of UAV Turbines.jpg

A Florida aviation startup wants to supplement electric power with its
watermelon-sized “microturbine.”

https://www.wired.com/story/uav-turb...-engine-drone/

For all the hype swirling around electric aviation, the current state of battery
technology and electric powertrains remains a limiting factor for all the
drones, air taxis, cargo haulers, and flying cars hoping to take off. Unhappy
with that cap on the range, power, and speed of these aircraft, one Florida
startup is taking a different tack. Rather than relying on batteries and rotors,
UAV Turbines is developing a tiny jet engine.

Just this August, the Florida-based startup flew its first microturbine-based
propulsion system, called Monarch 5, in a compact fixed-wing drone weighing
about 500 pounds, with a 22-foot wingspan. This quietjet engine can power
propellers, generate electricity for electric motors, or even produce its own
thrust. And while pocket-sized jet engines have been boosting radio-controlled
model airplanes for decades, the company calls the Monarch 5 the first
commercial-grade microturbine.

“The small UAV market uses aircraft—typically 500 to 1,000 pounds—that are too
small for real turbine engines but too large for just electric battery
propulsion,” says CEO Kirk Warshaw. “As a result they’re using motorcycle or
even weed-whacker-type engines ... Microturbine power can contribute to hybrid
systems, generate significant power for vertical liftoff and landing.”

Jet engines—aka turbines—have long been renowned for their performance. They can
send fighter jets to supersonic speeds or airliners halfway around the globe
with hundreds of passengers on board. They can generate more reliable power for
propeller aircraft than piston engines, power military tanks, drive cargo ships
at sea, or sit in boxes, generating electricity for remote work sites. And while
the airline industry has come under scrutiny for its contribution to climate
change, jets have made impressive efficiency gains over the past half-century.

The limit to their usefulness comes not at the big end of the spectrum—jets
power the world’s hugest planes and are growing larger by the year—but with the
little flyers. The smallest of small turbines could power a light business jet
or serve as auxiliary power units in larger aircraft, starting the bigger
engines and supplying electricity when parked at the gate. Even those weigh
several hundred pounds and are the size of a small refrigerator. Until now,
there haven’t been any tiny turbines for drones, robotic ground vehicles, or any
number of applications that would need efficient power generation beyond what an
all-electric system can provide.

UAV Turbines formed in 2000 via a merger of three model plane companies eager to
get into the then-nascent drone industry. They spent their early years upgrading
their small turbine tech for more demanding work, sweating heat management
fuel-burn efficiency and honing pressure ratios. “Modelers don’t need them to
fly that long, so getting 20 hours from a single engine is more than a year’s
worth of flying,” says Fred Frigerio, a senior vice president and program
manager.

The team had to design a newly small recuperator, which uses the exhaust to
preheat air entering the system, along with an engine control system to
digitally manage the turbine’s performance and enable easy on/off cycles during
long missions, when battery power might help out. They designed one of the
smallest commercial-grade variable pitch propellers, which is common on
turboprops and regulates aircraft speed by altering the angles of the propeller
blades instead of revving the engine up or down.

The result weighs just 80 pounds and is a watermelon-esque 18.5 inches long and
12 inches in diameter. It generates 200 horsepower and runs on standard jet
fuel, which Warshaw says appeals to potential military users who operate in
remote locations where electrical charging infrastructure doesn’t exist. It
doesn’t even have to make anything fly, he says: It could serve as an electrical
generator for radar or communications technologies, alleviating the wear and
tear on diesel truck engines that typically power such hardware now. In fact,
the company already has a contract with the Army to develop the technology for
its unmanned systems, and Warshaw says it has also been working with UAV
manufacturer Navmar Applied Sciences—which supplied the drone, called a
TigerShark, for the first Monarch 5 test flight—to develop propulsions systems
for its military applications.

Folks on the home front who are eager to commute by air will be more interested
in the system’s potential for the eVTOL market for passenger-carrying aircraft.
There, the microturbine could supply electricity to batteries powering motors in
hybrid configurations. It would also go into the the ever-exploding civilian
drone market, helping move cargo, inspect infrastructure, build maps, and
deliver packages. In those environments, once you need to go farther than 35
miles and are managing power-sapping hovering and vertical takeoffs and
landings, Warshaw, says, battery power alone won’t do the trick. The CEO
estimates the engine will be ready for these commercial UAV uses within just one
year.




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