<div><STRONG><FONT face="comic sans ms" color=#c00000>Yes, indeed, Alan!  A friend of mine was a B-24 pilot in WWII...he used to shake his head over a couple of pilots in his group who just couldn't hear (or see, since you can visually check through the props from the pilot's seat) that the engines were so far out of synch that they just beat up everyone on board for the entire run.  Talk about your four-string unison tuning...!</FONT></STRONG></div> <div> </div> <div> <TABLE class=messageheader cellSpacing=0 cellPadding=0 border=0> <TBODY> <TR> <TD class=label noWrap>From:</TD> <TD>"Alan Barnard" <tune4u@earthlink.net></TD></TR> <TR> <TD class=label noWrap>To:</TD> <TD>pianotech@ptg.org</TD></TR> <TR> <TD class=label noWrap>Date:</TD> <TD>Thu, 2 Aug 2007 17:25:05 -0500</TD></TR> <TR> <TD class=label noWrap>Subject:</TD> <TD>RE: Aviation Unison?</TD></TR></TBODY></TABLE></div> <DIV class="messageinfo separator"> <div><STRONG>Plain Text Attachment</STRONG> [ <A href="http://us.f810.mail.yahoo.com/ym/ShowLetter?box=Inbox&MsgId=9113_16733832_11957_1613_14506_0_69206_57973_3195404702&bodyPart=3.3.TEXT&YY=11475&y5beta=yes&y5beta=yes&order=up&sort=date&pos=0&VScan=1&Idx=17"><FONT face=Verdana color=#003399>Scan and Save to Computer</FONT></A> ] </div></DIV><PRE><TT>That's how aircraft engines were synchronized before they had computers to do it. A B29 pilot, for example would start one engine, then start the second and sync it to no beats by adjusting throttles, mixture, prop pitch, whatever, then the third, then the fourth. Otherwise the engines are "unequally yoked", as it were, and aren't as efficient and put torque stresses on the wings, I would think. Alan Barnard Salem, MO </TT></PRE><BR><BR><DIV>Stan Ryberg <BR>Barrington IL <BR><U>jstan40@sbcglobal.net</U></DIV>