Quote:
Originally Posted by Graham Boak
If it was still in good condition there'd be no reason to label it as "Weary". All aircraft have fixed structural lives, and the more they are used the nearer they approach failure. Nowadays this is closely monitored by the Fatigue Index, but before this came into use coarser methods of judgement were used. I don't know what methods were used by the USAAF or Luftwaffe, but some measure of total flying hours will have been involved. Even before reaching this limit, and accentuated by pulling high g, they can suffer structural warping. On a lower level, panels get bashed so that they don't fit as well as they used to. Gaps and steps appear. Skins get dented. This increases the drag. It becomes clear that this particular airframe is slower than its squadron mates. It doesn't accelerate as well, it doesn't climb as well, it doesn't turn as well, perhaps it's (comparatively) a bit of a pig to fly. OK for use in training, or for hack flying, but you don't want to take it into combat.
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If it was still in good condition there'd be no reason to label it as "Weary".
A mint condition P-51A would be labelled "Weary" when P-51B, C, D's became available and relegated to secondary units, it wouldn't matter how many airframe hours it had. Weary can also mean outdated.
All aircraft have fixed structural lives, and the more they are used the nearer they approach failure. Nowadays this is closely monitored by the Fatigue Index, but before this came into use coarser methods of judgement were used. I don't know what methods were used by the USAAF or Luftwaffe, but some measure of total flying hours will have been involved. Even before reaching this limit, and accentuated by pulling high g, they can suffer structural warping.
They didn't come close to racking up enough hours to approach airframe failure. Accidents or combat damage were the main problem. Structual warping would send an airplane to overhual or scrap.
If you take the B-17 Nine-O-Nine with 140 missions, average each mission at 10 hours long, that's only 1400 hours. Granted this is a lot of hours of combat time, but only a small dent in structural airframe time. Unpressurized, probably never exceedind 2G's, it could have flown for years. Most fighters only had a few hundred hours on them when retired, if not lost to accidents, combat damage, or replaced with new equipment.
On a lower level, panels get bashed so that they don't fit as well as they used to. Gaps and steps appear. Skins get dented. This increases the drag.
This miniscule amount of drag would be just about impossible to measure let alone detect.
It becomes clear that this particular airframe is slower than its squadron mates. It doesn't accelerate as well, it doesn't climb as well, it doesn't turn as well, perhaps it's (comparatively) a bit of a pig to fly.
The amount of damage needed to cause a measurable amount of drag to affect acceleration, climb, turning, etc., would render the airframe useless.