Actually, they made 3 blimps. But yes, they didn't include the most important one (hydrogen with different paint) for the comparison.

The scale model also fails to factor the thickness of the fabric, but it should nonetheless have provided some meaningful results.

I've seen other episodes that have bothered me a lot more with regards to missed or badly configured tests. The show's format has changed slightly in the past few years and I'm not as impressed with it anymore. There's too much intro schtick tacked on - their banter is usually just too unnatural/fake.

Has the show gone on hiatus for the past year? On Discovery's site I noticed it says the last newly aired episodes were from last summer.