## Re: [Flightgear-devel] Chinook Was: Re: Helicopter: First Impressions

 Re: [Flightgear-devel] Chinook Was: Re: Helicopter: First Impressions From: chris - 2006-06-29 18:49:25 ```On Wednesday 28 June 2006 02:37, Joacim Persson wrote: > On Tue, 27 Jun 2006, Maik Justus wrote: > > I'm working now on simulating the rotor on several points along the > > rotor blades (with twist). > > I suspect that twist to vary with load. The twist should not vary with load, but the coning angle will. > It's the tips that has a 12=B0 higher=20 > incidence (sic!) than the root, when the rotor is stopped that is. That is backward. The tip has washout ie it has a lower angle of attack th= an=20 the root. The idea is to achieve an even distribution of lift. The reason= =20 is that the velocity at the root of the blade in the plane of rotation is=20 much less than at the tip. If you had made the tips have a higher AOA the= n=20 all the lift would be concentrated there and either the blades would break = or=20 cone so bad it would not be able to take off. > I guess=20 > that's a pre-tensioning of the blade; that the lift moment on the blade (= it > has some naca profile if I remember it right) will twist it back to a more > straight shape under load or perhaps even twist it the other way. The older chinook had a modified naca0012 like most helis. That is a fully= =20 symmetrical shape and therefore there is "theoretically" no moment about th= e=20 blades long axix.=20 > > I have begun to develop some doubts if this reductionistic approach is the > way to go for simulating an aircraft that under normal operation is flown > with an electronic flight control system which does it best at making the > aircraft behave like a much smoother thing to fly than it is with the FCS > broken. What we want to simulate in the end is certain movements of the > aircraft following a certain input, not necessarily all the gory details = in > between that the pilot (normally) never have to worry about. > > But then again -- where's the fun in simplicity? ;) The chinook used to have just an "Stability Augmentation System" the SAS f= or=20 short. You still did not want to take your hands off the cyclic but it mad= e=20 it somewhat smoother. =20 ```