After having done some reading, I got a bit confused with the way some fighters are designed in terms of their structural strength.
Rafale, Typhoon and many other fighers are generally rated 9G/-3G.
I assume this refers to their limit load therefore their should be sized against 1.5 * 9G = 13.5G.
In civil aviation limit load is supposed to be the very maximum load that the aircraft is gonna see in its whole life. The ultimate factor then adds some extra fat in the structure to make sure the design covers for any scatter in the assumptions used in the stress analysis or funny things like build stress, manufacturing defect, ect...
The structure has to be designed so that no detrimental damage occurs until limit loads. Passed limit loads, permanent deformations, local cracking, delamination (composite) can occur as long as they don't compromise the safety of the flight until ultimate load. Clearly in principle you dont want to exceed limit load, and usually the FCS would prevent you from doing so.
In this video of Cedric Ruet prior to his Rafale display at Le Bourget 2009 (in french sorry)
the pilot does not seem to bothered when he says he pulls manoeuvres "up to 10, 10.5, even 11G sometimes" which if we believe the generic 9G/-3G above would be exceeding Limit loads....
I also came accross the presentation below which states (last page) that the Rafale static test specimen broke at 1.85 LL
, which suggest the airframe has some healthy margins in static (one could provokatively say it is well overweight....)
What does this mean? Has the actual Limit Load is not 9G anymore but something around 11G?
Even more suprising, I have been told (I cannot find any source to verify this) that the Eurofighter major static test specimen unfortunately broke at 1.4LL.
The link below explains how clever Eurofighter eventually negociated to get the usual ultimate factor of 1.5 relaxed down to 1.4 not to impact structural weight:
"The ability of carefree handling to control g limits precisely has allowed designers to reduce the ultimate load factor to 1.4, from the normal 1.5"
But still I am pretty sure I read somewhere about pilots pulling 10G on Typhoon....
Can anybody familiar with military plane design offer me some clarifications?