---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Thu 04/14/11: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:40 PM - Re: Re: JABIRU 3300 BRAND NEW OVER TEMPERATURE DURING TAXI (Bud Yerly) 2. 08:48 PM - Mono Landing Gear Question (Martin Tuck) ________________________________ Message 1 _____________________________________ Time: 06:40:33 PM PST US From: "Bud Yerly" Subject: Re: Europa-List: Re: JABIRU 3300 BRAND NEW OVER TEMPERATURE DURING TAXI Just a note on Jabiru 3300 (solid lifter) cooling issues on the ground and in the air that we've experienced here at Custom Flight Creations. We just finished about 100 hours of research and development trying to get Dr. John Kershner's Jabiru with the nice looking Andy Silvester Cowl to cool. Propeller is a 64 inch Sensenich Wood Prop. We drew heavily upon Sonnex, Jabiru techs and our own John Lawton's success. We have built a similar looking but two part lunch box over cylinder duct for ease of accessibility and maintenance. The duct is part metal and fiberglass. The between cylinder barrel and head gaps were extensively worked to optimize airflow, cooling pressures and heat extraction. Extensive work was done to try to direct and augment airflow through the square heads. (You know, air doesn't like to go around square corners or over and around those wires.) Our results are very promising. Taxi for 25 minutes before the hottest cylinder gets to 275F at 80 F outside no wind. I can live with that. Climb is possible to 3000 AGL at 75 KIAS and Max Continuous before we hit 304F (80F outside temp) then we must retard the throttle and accelerate to 90 IAS to keep the cylinders cool. At max continuous, it will stay right at max temp, however when we reapply full power, we are greeted again by temps going above redline, which is not acceptable. The cowl exit has been extensively modified as the supplied duct on the bottom has proven to be a ram air intake so we added a cowl flap to get a better draw. The cowl inlets are a bit small for the fin spacing as air rapidly goes through the fins without picking up the heat. The spacing of the cylinders fins and their thickness are partially to blame on the old engines, but we can't fix that. The new engines were refined, but alas are not interchangeable with the older engine. Oil Temps in the climb and 110 Knot cruise are within limits, thanks to a well sealed oil cooler, however, the oil temperature went up as speed increased above 120 KIAS at max continuous due to the poor design of the NACA and oil cooler placement. Yes it is true, as the speed goes up the air stalls at the oil cooler and decreases its efficiency to nil. More work needed, but trying to do it without messing up his paint is a pain. The engine at cruise will die if the carb heat is pulled and then the throttle retarded so we have a carburation issue still. It is just too lean it seems. Many things may be at play. We'll investigate one at a time. Shock cooling is a pain so the inlet has a dam on the front cylinders to help out, but it bears watching. We lazy Rotax people normally don't have to go to the cooling page of the EIS as part of our descent check, so make it part of your crosscheck. To our friend in Argentina: Thanks to Johns Lawton's and the Jabiru crowd's research, the mixture per cylinder has been identified as a problem in some of the stock engines. The induction system we found is prone to small leaks which leans the cylinders and causes high EGT and CHT. We are pulling the carb (again) to take out the owner installed lean kit. The smooth bore inlet to the carb is a good idea, but please ensure the hose clamps and rubber and gasket parts in the induction are sealing well. Also, the induction hose must be able to hold its shape and still be flexible enough to take engine movement. If that tube collapses your engine dies. My experience has been if your cylinders are running hot and the EGT is high, fix the induction, by either fixing air leaks, jetting the carb differently or moving the mixture clip or both. I have not tried rotating the carb off axis. John Kershner's plane was a 95 knot trigear and now goes 127 knots at max continuous with a speed kit properly installed and some cooling drag massaging. I was surprised that the 100HP 912S goes faster, but then again, prop speed and size and a gearbox multiplies the torque so they are about even as far as engines go with fixed pitch props. The Jabiru USA Rep, Pete K, was emphatic that tuning and cooling issues were best answered by using a Sensenich 62 inch wood prop. As the engine rpm passes 2750 or so, torque drops off and engine horsepower increases with engine speed but not a lot of extra power is felt. Propeller airplanes fly on torque so his assumptions make sense when comparing engine charts side by side. Most guys don't consider the torque multiplier of the 2.43 gearbox on a Rotax. The Rotax prop turns slower at 2250 RPM which looses out in potential thrust on a short 64 inch prop where as the short bladed Jabiru turns near 2750 RPM at max continuous. But it burns more gas turning that fast. The Jabiru is a nice looking engine that came on line before all the bugs were worked out, in my opinion, and it is a bit of time and patience to get it right. I have watched many folks on the net and after about 2 years of tinkering it works OK. I just had to look at it myself, as I have avoided the Jabiru in the past as heavier, thirstier, and harder to cool. I can make a Rotax cool with my eyes closed assembling the FWF. But what is life without challenges... I have put a couple thou of my own money into working out the deficiencies for my owners at the shop and we may do a cooling 102 on the Jab for those suffering in silence who are still willing to experiment... If it works, parts will be made available. Here's hoping that we get all the bugs out. Best Regards, Bud Yerly Still recovering from Sun 'n Fun. ----- Original Message ----- From: AirEupora To: europa-list@matronics.com Sent: Tuesday, April 12, 2011 10:05 AM Subject: Europa-List: Re: JABIRU 3300 BRAND NEW OVER TEMPERATURE DURING TAXI > I can not address this problem as I have not run my engine, but I was told by Jim McCormick to build a square box in front of the carburetor. I'll include a couple of pictures. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=336709#336709 Attachments: http://forums.matronics.com//files/carb_box_021_853.jpg http://www.matronics.com/Navigator?Europa-List http://www.matronics.com/contribution ________________________________ Message 2 _____________________________________ Time: 08:48:05 PM PST US From: Martin Tuck Subject: Europa-List: Mono Landing Gear Question When I replaced the brakes recently I thought the red rubber block (that has the vee's cut in it) which forms part of the landing gear suspension was looking a bit tired. I looked at some early photos of the aircraft and sure enough the top of the tire seems to be inline with the bottom of the fuselage whereas now the top of the tire is inside the wheel well by maybe 1/2 inch or so and both outriggers touch the ground whereas the aircraft used to tip from one to the other slightly. I assume I have to get a new block from Europa in the UK - but if it is something I can get here I guess it makes sense to buy it here and save on shipping costs. Same with the bungee cord which I might think about replacing at the same time. Anyone have to replace their block yet - if so, where can you get one? How about the bungee - what is the spec? I seem to recall someone coming up with an alternative solution to the bungee but I can't recall what is was. I think it included some kind of up-lock also. Any help would be appreciated. Regards, Martin Tuck N152MT Wichita, Kansas ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message europa-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Europa-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/europa-list Browse Digests http://www.matronics.com/digest/europa-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.