On Monday 17 January 2005 20:25, Dave Martin wrote: > On Monday 17 Jan 2005 17:06, Vivian Meazza wrote: > > Dave Martin wrote > > > > > On Monday 17 Jan 2005 15:31, Martin Spott wrote: > > > > Dave Martin wrote: > > > > > http://www.airshowphotography.com/videos/videos2.html > > > > > > > > Nice, a 45 degree turn just one wing-span AGL :-) > > > > > > > > Martin. > > > > > > I've been playing with the FDM and changing the line in > > > the yasim file: > > > > > > <flap1 start="0.75" end="0.95" lift="1.15" drag="1.3"/> > > > > > > to > > > > > > <flap1 start="0.75" end="0.95" lift="2.0" drag="1.3"/> > > > > > > seems to give a realistic response at low speed. > > > > > > Just changing the lift factor of the aileron makes the > > > detail in the videos > > > flyable and doesn't seem to give any unrealistic behavior > > > at full deflection > > > etc (50% deflection seems about the same as 100% at low > > > speeds). > > > > > > If anyone else would like to try her out with that lift > > > factor change we can > > > compare notes :-) > > > > The AN-225 is Lee Elliot's pet, but remember that air-shows > > are very often done with minimum fuel and no load. > > Heuristically, a lift factor of 2.0 is perhaps too high for > > a plain aileron. 1.2 - 1.5 would be normal, and with drag to > > match. But I agree that as it is the aircraft seems on the > > sluggish side. > > > > Regards, > > > > Vivian > > I was originally testing with absolute minimum fuel and I > could still get it into situations where it wouldn't lift the > inner wing from 45' bank at 170kts. > > I'm going to have a go with a figure of 1.5 for lift. > > One thing tho; the lift figure is the 'maximum' ie: at full > deflection. Could we expect that the Aeileron might make that > much at full deflection but such a deflection would also be > structurally damaging to the aircraft at above takeoff / > landing speeds. > > In the videos, the aeileron deflection used to induce high > rates of roll doesn't appear that much. > > Dave Martin
By all means have a go at tweaking any of the a/c I've done:) Be aware that flight testing is a very time consuming process though;) The point about the low fuel load for displays is pretty important - with a very low proportion of fuel on board the TOW is going to be around 700,000 lbs but the total thrust available i still going to be around 300,000 lbs - that's a pretty good thrust to weight ratio. On that other hand, at MTOW the AN-225 can't even taxi i.e. turn on the ground. In the video it looks like it's getting roll rates of about 20-30 deg/sec - I'll have a look into it myself a bit later. One thing that's just occurred to me is that I'd expect the roll rate to be higher at low TOWs because there's less mass to move. Has anyone any idea of what the minimum required roll rate would be for something like this? Another important factor with the AN-225 in the low speed regime are the slats but they don't seem to produce the pitch-up I'd expect. Dunno... LeeE _______________________________________________ Flightgear-devel mailing list [email protected] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
