I once took some BAe structural engineers on a tanking trip. They came along to see the effects of receiving on the tail assembly - pertinent as the tailplane sits in the efflux from the tanker's jetpipes. I had a look through the aft periscope while we were in contact and I can say I was "impressed" by what I saw. The whole tail assembly seemed to be flexing about a foot. But it wasn't that the engineers were concerned about. They seemed to think the tail could take it. What they were worried about was they way we were using the taiilplane incidence - in short bursts rather than longer applications. The stop-start nature of the short applications was stressing the mecahnism apparently.