You're right, there's nothing specifically about snap rolls, but the discussion (which is admittedly long and dated) is about designing a very high fidelity FDM which would presumably model aerobatic manoeuvres (like snap rolls) more accurately by it's very nature. The approach they are talking about is generating really large multidimensional tables from CFD data, and compressing the tables by fitting radial basis functions (both done offline), then at run time, using the fitted functions.
Just thought it might be interesting. Sorry, I now realise it is OT. Hugo. On Wed, 2006-06-14 at 20:46 -0500, Jon S. Berndt wrote: > There's nothing there about snap rolls. Can you copy / paste here? > > Jon > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] > Behalf Of Hugo Vincent > Sent: Wednesday, June 14, 2006 8:44 PM > To: FlightGear developers discussions > Subject: Re: [Flightgear-devel] Aerobatics using flight gear > and JSBSim > > > Sorry about that, prematurely hit send. Here is the link: > > http://forums.x-plane.org/index.php?showtopic=13050&st=0 > > Might be interesting, or maybe even relevant to modelling > things like snap rolls in JSBSim. > > Regards, > Hugo Vincent. > > On 6/15/06, Hugo Vincent <[EMAIL PROTECTED]> wrote: > I came across this discussion about adding a new open > source FDM to > X-Plane, using CFD methods to get really really high > fidelity models. > > > On Wed, 2006-06-14 at 20:32 -0500, Jon S. Berndt > wrote: > > Snap roll: > > > > This is indeed the recipe for a snap roll: starting > from a speed slightly > > above the stall, apply a sudden yaw with the rudder, > apply opposite aileron, > > and pull back on the yoke. SNAP! --- One wing stalls > and the plane rolls > > over. > > > > [I liked the clever use of the word, "recipe" with > the phrase "snap *roll*"] > > > > This would be hard to model using lookup tables, but > it might be possible > > using JSBSim functions and a table or tables, > together. Could be fun. I need > > to think about this one. The first idea that comes > to mind is that if the > > aircraft speed minus the yaw rate times some > characteristic lateral length > > (span/2?) falls below the stall speed, then a > rolling moment would be > > generated - maybe a yawing moment, too. > > > > Jon > > > > > > > > _______________________________________________ > > Flightgear-devel mailing list > > Flightgear-devel@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/flightgear-devel > > > _______________________________________________ > Flightgear-devel mailing list > Flightgear-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/flightgear-devel _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
