Gods of Strife, my character flies to London in the then-new Concorde supersonic airliner. I did a lot of internet research about the Concorde but there is a British Airways Concorde parked at the Museum of Flight in Seattle. I'd hate myself if I didn't make the effort to go there and see it. Now this was a three-hour drive. Admission to the museum was $16 (with a AAA discount) for myself and my oldest son. And, of course, we had to buy food in the Seattle area. So all in all, probably at least $150 spent and most of a day gone to do this research. I walked through the plane once and looked at it from the outside (and was able to compare it to a 747 parked nearby).
For all that, I ended up adding 92 words of description (out of an 87,000 word book). And a lot I learned in the visit didn't make it into the book because I didn't want to spend a bunch of words on description my character probably wouldn't notice. Plus my reader may not be as fascinated with airplanes as I am.
Here is the complete description of the Concorde from Gods of Strife:
Before we went down the jet way I looked at the aircraft. It seemed small and very skinny, with triangular wings and a very pointed nose. But the nose drooped as if someone had loosened some bolts. I assumed it was supposed to be that way as no one else was concerned. It didn't look like any commercial airplane I'd ever seen. It looked like a larger version of one of those fighter jets Graham pointed out in Tehran except for the white paint and that droopy nose. It was nearly as long as the 747 parked at the next gate but looked lithe and delicate compared to the hulk of the jumbo jet. The windows from the outside appeared to be miniscule.
The interior was very cramped and one had to duck going in the door. Perhaps it was only because of how slender the fuselage was but looking down the aisle the plane seemed very long. Although there were only two black leather seats per side they looked rather narrow, almost like tourist-class seats on a regular airplane. But they were almost as far apart, front to back, as in first class, giving plenty of leg room. I was surprised how comfortable they were when I sat down.
While you could stand up in the very narrow aisle, there was limited headroom over the seats, especially the one by the window which was only about the size of a paperback book.