> If I got you correctly, the tip of the rotor for most helicopters has > negative pitch at minimum collective (equal to the twist, e.g. -8.5° for > the bo, -9 ... -12° for the ch47).
Indeed. > On ground most helicopters are parked > with collective full down. Therefore it should be possible, to find > pictures of helicopters with huge negative blade pitch on the tip of the > rotor. Try to find such a photo for the bo or the ch47 ... Define "huge negative blade pitch angles". With collective full down and approximately 10 degrees twist in blades, the pitch of the blade tip will be in the order of 10 degrees down. Not something I would call huge: http://www.airliners.net/open.file/1146481/M/ http://www.airliners.net/open.file/0959909/M/ http://www.airliners.net/open.file/1080345/M/ http://www.airliners.net/open.file/1152408/M/ shows a puma and 3 chinook helicopter on the ground. Pitch angle at the blades of these helis is in the order of 10 degrees nose down. And for the front rotor of the chinook, you should take the high forward tilt of the rotor itself into account when determining the pitch angle of the retreating blade. Greetings, Wim On 12/20/06, Maik Justus <[EMAIL PROTECTED]> wrote: > Hi Wim, > wim van hoydonck schrieb am 19.12.2006 23:44: > > The minimum pitch angle at the blade root (or pitch bearing) for most > > helicopters is somewhere around 0 degrees, sometimes a bit more, > > sometimes a bit less. This is probably dictated by airworthiness > > requirements related to autorotational flight. If the pitch angle, and > > hence angle of attack would be too big during autorotation, drag on > > the blades would stop the blade in a matter of seconds, with > > not-too-nice consequences. > > > > > If I got you correctly, the tip of the rotor for most helicopters has > negative pitch at minimum collective (equal to the twist, e.g. -8.5° for > the bo, -9 ... -12° for the ch47). On ground most helicopters are parked > with collective full down. Therefore it should be possible, to find > pictures of helicopters with huge negative blade pitch on the tip of the > rotor. Try to find such a photo for the bo or the ch47 ... > > Maik > > ------------------------------------------------------------------------- > Take Surveys. Earn Cash. Influence the Future of IT > Join SourceForge.net's Techsay panel and you'll get the chance to share your > opinions on IT & business topics through brief surveys - and earn cash > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > _______________________________________________ > Flightgear-devel mailing list > Flightgear-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/flightgear-devel > -- Avoid hangovers - stay drunk! ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
