AeroBD | The AERO news Company… : Boom is a relatively new startup that’s aiming to build something pretty crazy. They’re not building an app… or a social network… or even some new gadget for the Kickstarter crowd. Boom wants to build planes. Really, really, really fast planes.

Specifically, they’re trying to design and build a supersonic passenger plane that goes 2.2x the speed of sound. If all goes to plan, they’ll be able to shuttle people from New York to London in 3.5 hours, and SF to Tokyo in 4.5.

Sound crazy? I wouldn’t disagree. It’s worth noting that the company is in the very early days for something as intensive, massive, and hugely expensive as designing and producing a passenger aircraft. They’re still working on their first prototype, and hope to fly it by late next year.

But it’s also worth noting that the team behind the plane has some serious talent in its blood: the company’s 11 employees have collectively contributed to over 30 aircrafts — having worked on things like the autopilot system on the 787, fighter plane engines, and flight dynamics on Spaceship Two. Some of these guys are ex-NASA, ex-Lockheed, or ex-Boeing.

Today, another big name is getting attached to the project: Virgin.

Boom is announcing today that Richard Branson’s Virgin Group has optioned ten planes, in a deal ultimately valued at about $2 billion dollars. Boom also says they’ve optioned 15 additional planes to a European carrier that it declined to name, bringing the total value of the optioned planes up to $5 billion.

Now, this doesn’t mean that Virgin has bought the planes — it’s a bit too early for that. They’ve signed a letter of intent, meaning that, having seen the nitty-gritty specs of the plane and the company’s plans for moving forward, they intend to buy 10 planes if everything comes together as planned.

But it also looks like Virgin is going to help make that happen: Boom founder Blake Scholl tells me that Virgin Galactic’s space division, The Spaceship Company, has committed to helping build and test the planes, including helping with the supersonic testing when the time comes.

Update: And now from the other side of the agreement, a Virgin Group spokeswoman confirmed their plans to The Guardian:

“We can confirm that The Spaceship Company will provide engineering, design and manufacturing services, flight tests and operations and that we have an option on the first 10 airframes. It is still early days and just the start of what you’ll hear about our shared ambitions and efforts.”

This company should be a wild one to watch. Building most real, physical things is hard — but building a passenger plane that goes faster than any before it, including the ill-fated Concorde? Thats a whole new level of hard.

Boom is funded by Y Combinator, Sam Altman, Seraph Group, 8VC, and other unnamed angels. Boom declined to comment on whether Virgin was providing capital as part of the deal.