Luminati Aerospace LLC, the Calverton startup that plans to build solar-electric airplanes, said Monday that two senior officials have departed the company.

Stefan Maier, the chief operating officer and an expert in composite materials, resigned from Luminati in late March, Luminati spokesman Jeremy Freeman said Monday. Senior scientist Anthony Calise, who in October 2015 described to the Riverhead Town Board his work on the guidance and autopilot design of the Patriot missile, resigned late last year, the spokesman confirmed.

The spokesman said the departures were typical of the “bumps and disagreements” of a startup company.

Telephone calls seeking comment from Calise and Maier were not returned.

The resignations, reported earlier by the news organization Riverhead Local, come as Riverhead Town officials hammer out a $40 million deal to sell to Luminati about 2,300 acres of the EPCAL (Enterprise Park at Calverton) property formerly used by Grumman Corp.. That sale is expected to close by late 2017.

Fifteen people remain on staff, Freeman said. Some are “still on the books but not working every day” as the company makes a transition from research to production.

Luminati chief executive Daniel Preston will announce a new leadership team on June 17, Freeman said. That is the date of a planned air show at the EPCAL site where Grumman tested F-14 fighter jets and the lunar rover.

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Luminati plans to make solar-electric planes that can remain aloft indefinitely and beam internet service to the ground. Luminati has said it has a financial backer, which it hasn’t named.

The company first came to light in October 2015 when it bought the hangar and the 16.3 acre property of Skydive Long Island at EPCAL.