On Fri, 17 Dec 2004 22:59:35 -0000 "Vivian Meazza" <[EMAIL PROTECTED]> wrote:
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.
Probably what we'd do for JSBSim if we were going to model this is to figure out the aero coefficient increments due to flap extension to specified points (perhaps pseudo "degrees" or in a range from 0 to 1). We might do this using DATCOM+, or using standard equations. Then we'd use a kinematic component to introduce the effects at runtime. For the next version of JSBSim we might even introduce the effects using equations, specified in the config file.
Jon
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