You can tell from the follow-on questions that the maneuverability requirement caught them flat-footed. As I read it, electric or "non-carbon" engines are a requirement. Hydrogen could fit that bill, but all hydrocarbons (like Methane)and all alcohols would be out. Obviously they want to sample for Carbon compounds. Can you think of any other way to propel it other than electric or Methane/Hydrogen, WW? I thought about compressed air but just no way to get two hours flight time. Interesting problem, would be fun to work on and right in our back yard (Cincinnati). Good discussion, WW. Warm regards, IndyJones.