Kartik wrote:JayS wrote:
Even I do not buy this marketing pitch that with CFTs its fully 9G capable. It seems very unlikely to me as well. May be when CFT are fully empty, but not with fuel in them. Because then they will have to strength the wings to take more G forces that the additional fuel weight adds, or the manoeuvre would take a significant life debit on the parts thereby reducing the life of airframe. Also lets not forget about sloshing in those tanks. With some amount of fuel in the tanks it would be sloshing like crazy while manoeuvring making CG management a nightmare unless there are compartments in the CFTs and fuel management system to take care of it separately.
The CFTs are not one large fuel tank. They are actually 4 separate sectional fuel tanks with just a fairing on top that gives them the look of one long contiguous tank. So they're contained in a smaller space and not sloshing about the entire length of the CFTs.
Again, if a layman can sit on his chair and think about sloshing, do you not think that the designers and test crew won't think of such scenarios? 3 dozen sorties that were done to qualify the CFTs were obviously done to check the fuel system functioning, the manevuer limits, monitor loads on the airframe, etc.
And if this test pilot's statement is marketing pitch, I must say, it leaves you open to the same criticism each time a Tejas TP says something good about it.
OK so sloshing is out of equation. But you totally missed "unless" in my statement.
The news item does not specify whether its fully 9G capable with fully loaded CFTs or not. And I find it hard to believe it would be so. If I see some technical arguments or credible factual info, I will accept (I will look for it myself when I get time). If I have to think that, ohh they must have thought about all that any layman like me can think and must have taken care of already, then there is really nothing remaining to write or discuss apart from rhetoric and half-baked theories about why someone did something with many assumptions and prejudices. I would just take anything that is said at face value. All aircrafts would be the best in the world. I haven't argued about claims over drag due to CFT. I know its possible to design CFT for older airframe designs with minimum drag penalty. I would also believe that empty CFT would allow 9G, but fully loaded CFT at 9G?? I have to see it to believe it. I have already said, even if its possible (Ultimate load not exceeded, which in all likelihood will not), it will have significant life debit on airframe *unless* they did some strengthening of the internal airframe. It has to add up to Zero somehow. I have already explained, ignoring drag, EFT with loaded fuel would be better for wing structure in certain aspects than equally loaded CFT under 9G manoeuvre.
And please, every single thing about LCA is questioned and discussed to death here. Almost nothing, except the statement that LCA handles better than M2K, is taken at face value, as far as I have seen. There can really be no discussion on that point. But there could be on this 9G capability with CFT with fuel in it. As such just because ADA guys or some TP says LCA is the best in the world, doesn't make it best in the world. It remains what it actually it. Those jingoistic statements are for laymans. Not for those who understand first thing about aircrafts.