Rick Ansell wrote > >Hi Vivian, > > > >Someone more familiar with parser might know how this is > read. Maybe > >as 0.94? In that case it wouldn't have any major affect on > anything. > >This error has been in there a while. > > > >The biggest problem I have with the p51d is that something > seems to get > >into the flight model when you shut down the power and rpm > (prop blade > >pitch) control. The aircraft seems to suddenly glide like > something is > >going wrong in the fdm. Maybe it is my imagination, but it > seems like > >I'll get the thing nicely trimmed for landing so that you > have to apply > >a little power to keep it on approach and above stall speed. > It feels > >right. Then once I get above the runway (still above ground effect > >height), it just glides much too well with all power shut > down to idle. > >Probably there are just some issues with modeling a > piston/prop setup > >with the power of a merlin, but I'm concerned that something > strange is > >happening at very low power settings. > > This possibly a side effect of trying to match the low > effective drag at speed of the Mustang. At higher throttle > settings the radiator & oil cooler assembly (in that 'hump' under the > aircraft) is set up to operate a little like a jet engine. > IIRC this offsets around 80% of the drag due to the > radiator/oil cooler. At lower power settings you get the drag back. > > I don't think Yasims solver is set up to account for this > sort of strange behaviour. > > Sorry to bang on about one of my hobby-horses again! >
Not only the clever radiator, but also the ejector exhausts ... They have both been exercising my mind recently. I think both could be modelled within the existing Yasim framework. They are both a source of additional thrust, and both have an associated drag penalty. On the other hand, the contribution of both is marginal, I feel. I would be surprised if the radiator drag, or lack of it effected the overall behaviour of the P51d model. I think there is something bigger at work here - an incorrect entry in the Yasim file, or an FDM error. I suspect something to do with the propeller right now. Regards Vivian Meazza _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
