Technically, you also have the compression of the wheels -- when the wheel turns, part of the tire in the front gets compressed while the back gets uncompressed. This is also a friction loss. Plus there is some friction between the rubber and the road.
But my point is that the amount of friction is wrong. The plane should not start rolling with a 3 knot wind, that's nonsense. Static friction is greater than dynamic friction. If you stop your car on moderately flat terrain with no brakes, it will not start to roll easily, not even if it's windy. If the terrain is flat, it will stay put. If the slope is greater, it might start to roll very slowly with the bearings turning in "stick/slip" mode and then finally it will just roll and accelerate. So the plane should stay put until there's a 20-30 knot wind blowing against it. Probably more on grass. On grass with the real plane you might need half throttle or more to get it moving. The funny thing is that this part seems to be modelled correctly in Flightgear, so no idea what's wrong with the effect of the wind :) Same goes for the prop, the resistance the shut down engine offers is too small and so it's turned over way too easily. Turning the prop of the Falke at about 2/3 of its span requires about the same amount of force as lifting an object that weights 1-2 kg. This is a rough guess and the actual force varies during the compression cycle but you get the idea. For the wheels, I can try to make sure that the brakes are always slightly set, but what do I do for the prop? Cheers, Vik On 07/05/2012 03:30 PM, Emilian Huminiuc wrote: > On Thursday 05 July 2012 15:21:24 Viktor Radnai wrote: >> 1. When the aircraft is parked with no parking brake, it will usually >> start to roll slowly backwards -- pushed by the wind and maybe the >> runway slope. If I start the engine on idle, the thrust generated by the >> idle prop might stop this roll. On tarmac, even a 3 knot wind is enough >> to start pushing the plane back. On grass more is needed -- maybe 20 knots? >> > Hi, > > In that case, even in real life, there's no other friction at play than the > friction inside the wheel bearings, friction which is very low, almost > ignorable. > > Regards, > Emilian > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Flightgear-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/flightgear-devel > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Flightgear-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/flightgear-devel
