Hi Wim wim van hoydonck schrieb am 18.12.2006 23:23: > Hi Maik, > > > Once our library opens again next year (they are moving to a new > building), I'll cross check that data with Janes (I work at the > faculty of aerospace engineering in Delft). > > very good, thank you! >> Very surprising for me are the >> cyclic/ collective data with approx 20+18=38 degree maximum incidence of >> the main rotor. >> > > That's the maximum pitch angle at the root of the blade which is not > the same as the angle of attack of a blade (element) along the span of > the blade (inflow induced by the rotor itself reduces the angle of > attack). yes, but it is still the double value than the bo. But the incidence data I have for the bo is measured at 0.7r and therefore much smaller.
>> Unfortunately I do not have any information about the >> airfoil (SC1095). >> > > This ([1]) NASA report contains some data about wind tunnel test done > with that airfoil. > > Perfect. With this data I can calculate the data for the .xml file. >> One important point: the main rotor and the tail rotor >> are twisted. Do you know, where the incidence is measured? >> > > Pitch angle (theta) is normally measured from the root of the blade, > as can be seen in [2], page 322. I am not sure if that matches the data. With 8° twist and -1.4° pitch at minimum you will get -9.4° at the tip and something about -7° mean (weightened with r^2). In autorotation you will get much overspeed. The data I have for the bo is measured at 0.7r. The effect is, that a pitch of 0 degree gives approx. in the same lift as a blade without twist. > Flight path angle (phi) is calculated > >from the tangential and normal velocity components at a blade element > and the angle of attack (alpha) is the difference between (or sum of) > these two (depending on the choice of positive axes). > > >> Do you have such data for other helicopters in your book (bo105 (but >> here the actual data should be correct), ec135, ec145, ch47d, s76c, >> little nellie)? >> > > I have access to the majority of editions of Janes All The Worlds > Aircraft between 1976 and 2006, so yes :) (although I'm not sure > about little nellie ...) > > One important point for the simulation: most rotors have a delta3 effect (this means: reducing the pitch with increased flapping angle). Do you know this parameter for the ch53e (or for other helicopter?) > Greetings, > > Wim > > > [1] http://halfdome.arc.nasa.gov/publications/files/NASA-TP-2003-212265.pdf > [2] > http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960054374_1996092848.pdf > > > Thank you, 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
