On Wednesday 09 June 2004 17:03, Vivian Meazza wrote: > Lee Elliott > > > On Tuesday 08 June 2004 23:01, Vivian Meazza wrote: > > > Andy Ross wrote > > > > > > > Chris Metzler wrote: > > > > > Sometimes I run into issues with FlightGear -- fgfs, data, > > > > > scenery, whatever -- that I'm reluctant to report because I'm > > > > > concerned that the developers already know about them; > > > > > > > > Indeed, that's a good idea. We've been known to kill and eat > > > > reporters of known bugs. :) > > > > > > > > As for using a bugzilla or whatnot, I'm neutral. I find that I > > > > always end up fixing the bugs that people whine about the most > > > > anyway. Bug tracking systems tend to fill up quickly with > > > > "not-quite-bugs" that no one wants to look at. > > > > > > Speaking of which, is there any progress on the Merlin propeller > > > gearing issue? > > > > > > Regards > > > > > > Vivian > > > > I was having similar problems with the Comper Swift geared > > prop and at one > > point I was getting the right power and rpm but at the wrong > > mixture and fuel > > flow rates - both seemed out by approx the same ratio as the > > prop gearing. > > > > I haven't looked at it for while but I'll try it in the next > > few days or so > > and see what the situation is with it now. > > Ta. The Spitfire model is nearing completion, and I need to fly it to test > the sounds etc., so I would be grateful if we could sort this one. > > Vivian
I did some ground running tests on the Comper Swift today, after updating the YASim config to use the new piston-engine sub-element of propeller, and tried different combinations of engine and propeller rpms. The gearing on the Comper Swift was 0.47 and the max engine rpm was 3300 rpm so I tried ungeared settings with the with both the prop and engine rpm set to 3300, and then 1551, and got the following results:- rpm_____Max rpm_____Max PT______Fuel Flow 3300____3306________267_________9.68 1551____1553________264_________9.68 This seemed ok and the a/c performed about right too. However, when I introduced gearing at 0.47, so that the engine was rated at 3300 rpm and the prop at 1551 rpm I got the following numbers:- Max rpm_____Max PT______Fuel Flow 2205________117_________6.45 A quick bit of math with the numbers produced for PT: 117/267 = 0.43 - this is close'ish to the gear ratio. 117/264 = 0.44 - even closer. for eng rpm: 2205/3306 = 0.666 2205/1553 = 1.419 for fuel flow: 6.45/9.68 = 0.666 The way that the geared rpm slotted between the eng and prop rpms seemed curious too:- (3300+1551)*0.47 = 2282 (3300+1551)*0.43 = 2085 (3300+1551)*0.44 = 2134 just out of curiosity (3300+1551)*0.4545 = 2204 Allowing for the fact that YASim will be generating a different solution for each combination, so I'd expect some variation in the results, some of the numbers seem as though they might be significant, but as to what exactly they signify... LeeE _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
