Fatigue life in Aircraft (particularly Fins)

[Garry Russell]

Is it true..........or just rumour....that even with a tame Vulcan display, as it stand at present there is only about ten years in the frame???

Garry

[ukmil]

that is true, and is based on average hours and Fatigue use. if you flight straight/level, you can extend this

[forthbridge]

Is there much of an impact on the fatigue depending on what the aircraft carries and where?

For instance, say two identical Jaguars flew with identical weights attached, with AC 1 having them on the underbelly, and AC2 on the inner wing pylons,
and their sorties and T/O weights were identical, would this significantly alter one aircrafts' life expectancy?

Does the addition of stores in general add to the fatigue index?

Does drag come into play as well as weight?

[ukmil]

indeed, take the F3 for example, if we have 2 flying the same sortie profile, but one is wearing underwing tanks, it will eat more fatigue on the wings and centre fuselage

[Chris Sykes]

with regards to the vulcan i thought FI wasnt the matter, but the engine life cycles was the factor???

[ukmil]

if it were engine hours, that would not have a restriction on the airframe, and the engines can be overhauled, but the airframe cannot. once an airframe meets its FI, only the DA can authorise an extension, of which the vulcan cannot get. The engines can simply be overhauled. i say simply, but on the Vulcan, it is not that easy as cost and parts are the issue.

As far as I am aware, through my in house contacts, the Vulcan is restricted in it's use, simply down to the airframe mainly, but yes, engines and costs are also a huge factor

[Quixoticish]

If memory serves the "plan" for the Vulcan was only to display it for a maximum of ten years anyway before retiring the airframe to a museum. If I remember correctly this was written into the terms and conditions when the heritage lottery fund handed over their cash, whether they set the 10 year deadline to do with FI and engine cycles or whether it just seemed sensible at the time I'm not sure.

[ukmil]

indded very true, but it seems the vulcan will not last 10 years anyway, due to funding.

[jonesey2k]

I think I read somewhere that if you look out the periscope when doing that you can see it shaking?

[Chris558]

Tonks, I remember reading that they once set the angle of the VC10's ailerons slightly upwards. This counteracted the upward force, stopping the wings flexing too much, and so relieving the stresses. Only it was a bit too much, so I think they reduced it or stopped it.