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George, the total distance from the intake port opening in the combustion chamber to the center of the throttle body is a nominal 21 inches. This can be varied from 19" to 23" by adjusting a clamp and sliding the upper portion of the tubes (attached to the TB mounting plenum). The velocity of sound decreases with decrease in temps (and vice versa) so for winter time, I adjust the intake to a shorter length( to account for the slower velocity) and in summer time I adjust it to the longer length(to account for the higher velocity of sound). My calculations show that for a 100 F manifold temp the length should be (depends on the intake porting) a nominal 21.25" and for a manifold temp of 50F the length should be a nominal 20.25" So 21" is not that far off either way. If the manifold temps vary wider than that then the distance will vary as well. Its actually the timing that is critical, so we have time = distance/speed. So to keep the time the same, if the speed (of sound) decreases then you must decrease the length(distance) and if the speed increase then you must increase the length to keep the timing the same. Now this is all based on a engine speed of 6000 rpm. The rpm will change the required length. I elect to tune my intake for 6000 rpm because that is my take static/off rpm and I want my maximum power on take off. If I were an air racer then of course I would tune it for a much higher engine rpm (but, I'm not {:>)) Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html ----- Original Message ----- From: "George Lendich" <lendich@optusnet.com.au> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net> Sent: Friday, October 05, 2007 5:59 PM Subject: [FlyRotary] Re: ATTENTION YOU ARE AT RISK... So Ed - what sort of length did you end up with and how much did it vary for summer and winter. George ( down under) You are correct, Scott. The in-flight adjustable intake simply did not work out as hoped for reasons I explained in a previous e mail. However, the adjustable DIE intake works just fine and gives me the power I want on take off. I tried for a couple of months to get a 4 tube sliding mechanism to work, but the precision required, weight of the intake, etc. just didn't work out. So tried the compromise which worked mechanically, but compromised the very effect I was hoping to capitalize on. But, that is what experimenting is all about. If you don't ever fail then you are not experimenting {:>). I have built five different intakes, but found that my second design was the best and a refined version of that is what I have been flying with for the past three years. Sorry, the in-flight adjustable is just to big and heavy to throw into the baggage compartment, but if you are ever down in my neck of the woods, be happy to show it to you. Ed ----- Original Message ----- From: "Scott" <squiggles@yahoo.com> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net> Sent: Friday, October 05, 2007 9:00 AM Subject: [FlyRotary] Re: ATTENTION YOU ARE AT RISK... *uncomfortable silence* Well....Ummmmmmm....Aaaaaa.... Hmmmmmmmm.... I thought it didnt work very well, something with the nickel coating and motor drive... So you got everything worked out? Understood about the plugs up, I was interested in how the sliding tubes are sealed and the drive mechanism... ____________________________________________________________________________________ Fussy? Opinionated? Impossible to please? Perfect. Join Yahoo!'s user panel and lay it on us. http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7 -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.488 / Virus Database: 269.14.1/1050 - Release Date: 4/10/2007 5:03 PM -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html