Electric propulsion developer Whisper Aero is working with the U.S. Air Force to develop a new family of quiet, efficient, autonomous aircraft for contested logistics, with initial flight testing scheduled for 2027.
Whisper on Tuesday pulled back the curtain on a pair of Collaborative Logistics Aircraft (CLA) concepts, designed to carry 500 pounds (CLA Light) or up to 3,000 pounds (CLA Heavy) of cargo while operating from austere or degraded runways. The effort is backed by Strategic Finance Increase (STRATFI) and Operational Energy Capabilities Improvement Fund (OECIF) contracts. Whisper said autonomy and manufacturing partners will be announced soon.
Whisper does not build aircraft—rather, it develops technologies designed to make them more efficient. Core to the company’s offering are specialized electric ducted fans, which it says are quieter than competitors’, and a family of proprietary electric quiet (eQ) engines.
The firm has been exploring defense applications since emerging from stealth in 2021. It has already designed, built, and flown a Group II demonstrator drone integrated with its propulsion systems. Whisper on its website also describes a “next-gen caravan” that sounds a lot like the CLA concepts: a “larger aircraft” that “operates in austere environments where minimizing acoustic footprint is mission critical.”
The Air Force is already exploring several autonomous concepts built around existing airframes, such as the Cessna 208B Grand Caravan. But according to Whisper, future autonomous designs will require greater fuel efficiency, runway flexibility, and affordability.
“Today’s joint air mobility portfolio relies heavily on large, fuel-hungry, runway-dependent aircraft that strain operational resilience,” the company said in a news release. “Shorter, less-maintained runways left over from World War II in the Pacific and other theaters make future contested logistics especially challenging.”
That’s where CLA comes in. Inspired by the Air Force’s Collaborative Combat Aircraft (CCA), the CLA Light and Heavy incorporate Whisper’s eQ250 propulsors in the leading edge of the wings, using a concept it calls JetFoil. These can be integrated on a variety of aircraft.
“Instead of one singular platform, Whisper believes that cargo missions will increasingly rely on distributed fleets of right-sized logistics UAS [uncrewed aircraft systems] capable of operation from austere runways at any time of day,” the company said.
Whisper said multiple eQ250 engines will each provide 80 pounds-force of thrust while achieving coefficients of lift as high as 14, enabling short takeoff and landing (STOL). Engine efficiency is expected to improve at higher speeds. At 250 knots, CLA aircraft would generate reduced noise and heat signatures compared to existing models, the firm said.
The CLA Light is a Group 3 UAS with a dash speed of 175 knots and ferry range of 2,000 nm, shortening to 200 nm at full 500-pound payload. On its main wing are 12 eQ250 engines, enabling takeoff and landing with just 50 feet of ground roll. Adding to the STOL capabilities are a 40-kilowatt powerplant and battery. Its nose opens easily for cargo loading and unloading.
The larger CLA Heavy, at 10,140 pounds, can carry 3,000 pounds of cargo over 800 nm or ferry 3,000 nm. Its payload bay can be reconfigured for different mission types. Thirty higher voltage eQ250s across the aircraft’s 50-foot wing reduce its ground roll to 300 feet, while a 600 kW powerplant powers it to speeds up to 250 knots. Unlike the uncrewed CLA Light, the model is optionally piloted.
“Without the need for a pilot on board, these aircraft are designed to be more affordable and attritable,” Whisper said. “They can reposition themselves with greater fuel efficiency, prioritizing energy needs for other aircraft in the fleet.”
Whisper said it is taking a “crawl, walk, run” approach to flight testing with the Air Force. It will begin with the Ultralight—a retrofitted Swift3 glider equipped with two eQ250s. The company will fund that testing itself. After that, the plan is to begin flying with the Air Force at White Sands Missile Range in 2026 using STRATFI and OECIF funding.
Once the Ultralight is airborne, development will shift to the CLA Light, with flight tests expected in 2027, followed by the CLA Heavy. The goal is to fly multiple full-scale variants and, within four years, gauge how the technology performs in service.
Beyond defense, Whisper’s electric propulsion technology has found uses in consumer products such as leaf blowers. The company has also released concepts for a regional Whisper Jet and more robust 100-seat model, both based around its ducted fan and eQ engine technology.
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