Lithium-sulfur-powered eColt in works

The eColt should achieve an initial flight time “in excess of two hours” and an approximate range of 200 nautical miles, according to a Texas Aircraft Co. and OXIS Energy joint news release.

Advances in battery technology have propelled the idea for electric-powered general aviation aircraft from drawing boards to airport ramps. Several companies are pursuing electrically powered solutions, but a limiting factor has been the heft of the rechargeable batteries and an accompanying power-to-weight ratio that lags far below the lifting efficiency of avgas- or Jet A-powered aircraft engines.

The British battery firm plans to change that thinking by introducing lighter-weight rechargeable lithium-sulfur technology for the high-wing, all-metal, fully electric aircraft rather than the heavier lithium-ion (Li-Ion) counterpart pursued by other electrically powered aircraft manufacturers.

Lithium-sulfur batteries are “promising because of the high energy density, low cost, and natural abundance of sulfur material,” according to a report published by ScienceDirect.com. The technology could be one route to unlocking the electric motor power-to-weight secret. Bye Aerospace of Colorado, which seeks to certify all-electric aircraft, also partnered with OXIS in 2019 to power aircraft with lithium-sulfur batteries. Lithium-ion-powered devices have been known to heat up very quickly and are also volatile when breeched and exposed to oxygen. Lithium-sulfur is also a potentially volatile mix, but the high energy density is tantalizing, and the risk posed by the chemistry and physics could be reduced by mitigations built into the battery designs. OXIS said in 2019 that the company’s lithium-sulfur batteries have demonstrated high tolerance for physical damage, and longer cycle life compared to other lithium-based batteries.

The eColt’s “90kWh battery system, which is 40 [percent] lighter than current Li-Ion technology” will be powered by a high-power cell “at 400Wh/kg.” OXIS Energy CEO Huw Hampson-Jones said that lithium-sulfur battery technology “offers significant benefits” to aviation. The use of sulfur as a “non-conductive material provides enhanced safety and is superior to current Lithium-Ion technology,” a July 21 news release noted.

Texas Aircraft Manufacturing CEO Matheus Grande said a position “at the forefront of the transformation [of] Brazil’s private aviation to all-electric power is an amazing opportunity.” He added that the aircraft’s “wide cabin and exceptionally pilot-friendly flight characteristics” would make the eColt “a fantastic airplane for flight training and personal transportation in Brazil and around the world.”

The Hondo, Texas-based airplane maker announced the $156,000 Colt-S and $167,000 Colt-SL in 2019, but a price was not yet published for the eColt. The company has a manufacturing facility in Campinas, Brazil, where the electric aircraft’s key airframe and power components will be made.