Boom has a new design for its XB-1 Supersonic Demonstrator jet, the working prototype aircraft it’s creating to prove out its tech before beginning work on building real, commercial supersonic passenger aircraft. The new design was revealed Tuesday at the Paris Air Show, along with new business milestones: Boom has orders for 76 aircraft thus far, across five airline customers.

That’s a lot of orders booked for an aircraft that doesn’t actually exist yet, from a small startup, but you can tell why airlines are excited. Boom’s promise is one of reducing flight time significantly on popular intercontinental business routes, with economics that will roughly match current business-class fares for travelers while offering sustainable economics for airplane operators at the same time.

The new design of the XB-1 includes refinements that the company says will offer better stability overall for the propulsion system and boost overall safety. Parts for the demonstrator had been undergoing stress testing recently, which has likely helped contribute to these design changes.

The most immediately apparent design change is the new, third inlet mounted on the tail, but there are other subtle changes to the wing and main body shape, too.

As for Boom’s new bookings, the company notes that these reservations include non-refundable down payments, which will help with the bottom line in the near-term. And regarding what those will look like in production, Boom has offered up some concepts, including renders of luxury cabin appointments like lay-flat seats.

Boom is aiming to fly the XB-1 Demonstrator next year, first with subsonic tests near their HQ in Denver, then with supersonic flights to assess those capabilities at Edwards Air Force Base in Southern California.