A typical hangar is 100 yds x 50 yds, similar to a football pitch.
It was a bit surprising therefore that the piece linked to says the new facility will be "the size of two football pitches", when the Science Museum currently has 10 hangars at Wroughton. From 10 to 2. I'd much prefer they considered the hangars part of the museum, but agreed that something is better than nothing.
I wonder what's in the 20% that won't make the cut? Indeed how is the 20% measured? By numbers of artefacts? Or by volume? I suppose if you get rid of a Comet aircraft, you could fit a rather large number of fuel pumps, tires, paperwork and other detritus in the same space, but 8 yr old little Billy/Joshua/Mohammed isn't going to get the same inspiration.
A bit of "bah humbug" here, perhaps; something better than nothing. But why not just repair what's already there? The RAF have to.