Hey Mark. Yes, almost everything is indoors. When I was there a few years ago the X-planes were stored on the AFB and we had to bus out to them. They turned us loose in dreamland, really a monster hanger for one hour. All they said was not to touch anything. Wow! We walked around and under dozens of one of one of a kind stuff. XB-70, X-15, A-12 and on and on. This collection is now housed in a new addition.
Dayton is the best air museum in the world. Anyone with a interest in aircraft should see it. They have a great web site and even 360 virtual cockpit tours. Anything that was ever captured in war was evaluated and stored at the museum. MIG 29, German Komet, missiles and such along with everything the Air Force had. including spy satellites, nukes, missiles and more. Hundreds of Aircraft on display, hundreds on loan or being restored. What a place!
Max