Cardboard mock-ups are extraordinarily helpful in making real the space that will define the product (as opposed to CAD drawings). They are regularly used in rapid prototyping.

The fact that they aren't waiting before having a final metal frame before testing for instrumentation fit is a plus in my book.

Presumably they're just testing the ergonomics of their seat/cockpit layout, or something along those lines. Unless you're worried that they're actually going to try to build an airplane out of cardboard, I don't see what the problem is.

This is what a scrappy airplane startup looks like in the early days. The wooden mockups validate sizing and ergonomics before you lay down expensive carbon fiber.

"Unless you're worried that they're actually going to try to build an airplane out of cardboard"

I dunno. They do say "carbon fiber" a lot... and that is a description of cardboard....

Carbon fiber is incredibly strong when engineered properly:

"During the test, the wings on the 787 were flexed upward “approximately 25 feet” which equates to 150 percent of the most extreme forces the airplane is ever expected to encounter during normal operation. The test is used to demonstrate a safety margin for the design and is part of the certification process to show the airplane can withstand extreme forces."

I don't know what a foot is any more, but here's a video of the A380 doing its wing flex test:

https://www.youtube.com/watch?v=B74_w3Ar9nI

This is called Lean Design and saves millions http://www.leanconstruction.org/about-us/what-is-lean-constr...

What does not inspire confidence in me is that they are toying around with what appears to be a small General Electric CJ610 turbojet engine, developed in the 60s from the earlier J85. Doesn't seem like the best propulsive plant for a supersonic airliner!

Their engine: http://boom.aero/assets/press-bg-7481f004eff02964a90134c6a46... Reference picture: http://i163.photobucket.com/albums/t301/planedr2k7/100_0177....

A CJ610 engine doesn't have complicated electronics to integrate, and would allow aerodynamic test data from a subscale model. For comparison, the two J85 engines in a F-5E could push it to over M1.4 at altitude.

There might even be a wooden plane or two before they get around to actual carbon fiber and metal.

http://business.financialpost.com/news/assembly-of-bombardie...