Lee Elliott wrote > > > [snip...] > > > > How do FDMs handle Fowler flaps? i.e. the first part of the > > action extends the flap rearwards without any rotation, acting > > only to increase wing area, then for the rest of the action > > rotate downwards? > > > > Easy enough to 3d model with a normalized input: translation > > then rotation. > > > > Just curious > > > > Vivian > > That's exactly one of the problems I'm trying to work out wioth > the B-52. The flaps have only two settings - fully extended or > fully retracted, and it took 60 sec for full traversal. IIRC, > the first 60%, or so, just increases the wing area, with the > remainder changing the downwash. I've no idea what YASim is > doing, as far as numbers go, but it seems to be behaving close > according to anecdotal evidence. > > Perhaps flight control surfaces should be defined in terms of the > change to chord and incidence but then how do you get the data? >
Andy Ross will be able to explain in detail, but as I understand it YASim handles all kinds of flaps the same. The lift and drag increase is specified in the config file, then YASIM applies a proportion of both according to how far the flap is extended. I haven't investigated the function which is applied. It might be linear, or some other. I'm not sure if lift and drag are treated equally. Given how little we know about the real numbers for the likes of the B52, I guess that's good enough. I suppose that, in fdm terms, you could regard Fowler flaps as 2 separate flaps. In principle, some function, or functions could be applied which would cater for the first part of the movement, and then the second. Regards, Vivian _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
