Dene Several years ago, while at Oshkosh, Richard Shirley was there with his 3300 Jabiru powered KR-1. He was having cooling problems, especially at high cruise sppeeds. Out of curiousity, I attended a seminar at Airventure on how to achieve good engine cooling performance. The seminar was taught by a reputable thermodymanist. She recommended that the cooling exits areas be on the lower side corner of the cowling. This area is a low pressure area and helps to suck the hot air out better than the center of the cowling at the bottom. She recommended that area for your exhaust which is already "pressurized". Check to see if Oshkosh has a record of who she was. It was Airventure 2006. With some luck, you might be able to then find and read some of her research.
Hope this is of some help. Pete Klapp, building KR-2S N729PK, Canton, Ohio > From: k...@bigpond.com > To: kr...@mylist.net > Subject: RE: KR> 3300 Jabiru to cool correctly > Date: Tue, 8 Dec 2009 08:03:29 +1000 > > Hi Dene > > We had simular problems on a Zenair. No matter how big a lip we put on or > how big the cowl exit it would overheat. > My opinion was that the shape of the cowl and the underside of the aircraft > caused a high pressure area at the cowl exit underneath. > > We put vents (like gills) on the side of the cowl for a 20 degree Celsius > drop in temperature. All Good :-) > > > Regards > > Barry Kruyssen > k...@bigpond.com > http://athertonairport.com.au/kr2 > RAA registered 19-3873 > Australia > > > > -----Original Message----- > From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On Behalf > Of Dene Collett > Sent: Monday, 7 December 2009 3:24 PM > To: KRnet > Subject: Re: KR> 3300 Jabiru to cool correctly > > I have tried all kinds of lips of various sizes at the exit to no avail. I > also have an in flight adjustible flap that hinges down to open and close > the exit which forms a hige "lip" when in the full open position. It also > has sides as we thought the air being displaced by the flap was spilling > round the sides of the flan satisfying the low pressure at the mouth of the > exit...... no luck. The air inlets were sized the same size as the four > seater Jabiru aircraft which uses the same motor. What was not taken into > considderation was the fact that the motorglider flies at a much lower > airspeed than the Jabiru. My next experiment is to enlarge the inlets and > see what difference that makes. > Regards > Dene Collett > Avlec Projects cc > Port Elizabeth > South Africa > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html _________________________________________________________________ Windows 7: Unclutter your desktop. Learn more. http://www.microsoft.com/windows/windows-7/videos-tours.aspx?h=7sec&slideid=1&media=aero-shake-7second&listid=1&stop=1&ocid=PID24727::T:WLMTAGL:ON:WL:en-US:WWL_WIN_7secdemo:122009
