Keenaviator Posted May 7, 2014 Share Posted May 7, 2014 [medio=full]448[/medio] 6 Link to comment Share on other sites More sharing options...
Keenaviator Posted May 7, 2014 Author Share Posted May 7, 2014 Very pleased with the way this machine has turned out. It flies straight and engine temps and pressures excellent - the under cowl mods work a treat. It's running a bit rich (exhaust pretty dark and a slight miss at WOT above 2500' that gets worse with carby heat as expected - will investigate jetting/needle position). It glides very nicely too with those long wings. Sink rate at MTOW about 400 fpm (engine off with CFI for company). Cheers, Laurie Link to comment Share on other sites More sharing options...
gandalph Posted May 8, 2014 Share Posted May 8, 2014 [medio=full]448[/medio] Congratulations Laurie, It must be very satisfying to see all your work and effort come to fruition. What under cowl mods have you included? 1 Link to comment Share on other sites More sharing options...
Keenaviator Posted May 8, 2014 Author Share Posted May 8, 2014 I worked on ensuring a good pressure differential between the top and bottom of the motor. I shifted the oil cooler off the sump and fitted a larger Serck cooler with AN6 fittings (fitted larger fittings to the oil cooler adapter to improve flow) at the rear of the engine on the airframe instead of the engine so it is not subjected to as much vibration. This oil cooler has a naca duct with a 2" scat hose leading to it (air flow controlled by a butterfly valve that can be adjusted by the pilot). Next I reduced the size of the old oil cooler air inlet beneath the spinner (bottom of cylinders) by about 80% and fitted a close fitting duct to the sump to direct some air through the cooling fins cast into it. - this meets neatly with the air inlet below the spinner. I closed up the holes in the Jabiru cylinder cooling ducts (couldn't see much point in giving air another option other than through the cooling fins) that allow a small amount of air to bleed into the area between the top cowl and inner of part of the cylinders and crank case. I'm very happy with the results. Flying today in cool conditions around 15C at 2500' CHT was around 90C and oil temp 80C with the air shut off from the oil cooler. I opened the air valve and a short time later I saw the oil temp coming down further; closed it and it settled at 80C. Laurie. 1 Link to comment Share on other sites More sharing options...
gandalph Posted May 9, 2014 Share Posted May 9, 2014 I worked on ensuring a good pressure differential between the top and bottom of the motor. I shifted the oil cooler off the sump and fitted a larger Serck cooler with AN6 fittings (fitted larger fittings to the oil cooler adapter to improve flow) at the rear of the engine on the airframe instead of the engine so it is not subjected to as much vibration. This oil cooler has a naca duct with a 2" scat hose leading to it (air flow controlled by a butterfly valve that can be adjusted by the pilot). Next I reduced the size of the old oil cooler air inlet beneath the spinner (bottom of cylinders) by about 80% and fitted a close fitting duct to the sump to direct some air through the cooling fins cast into it. - this meets neatly with the air inlet below the spinner. I closed up the holes in the Jabiru cylinder cooling ducts (couldn't see much point in giving air another option other than through the cooling fins) that allow a small amount of air to bleed into the area between the top cowl and inner of part of the cylinders and crank case. I'm very happy with the results. Flying today in cool conditions around 15C at 2500' CHT was around 90C and oil temp 80C with the air shut off from the oil cooler. I opened the air valve and a short time later I saw the oil temp coming down further; closed it and it settled at 80C. Laurie.[ATTACH]28862[/ATTACH] Thanks Laurie, Good to see someone who understands and works to the basic principles. How 'bout some pics of the under cowl work? 15c ambient is fairly cool, sounds like southern highlands weather. It will be interesting to see what results you get on more extreme days. What's the vertical gauge mid panel? Do you plan to monitor all CHT's & EGT's? 1 Link to comment Share on other sites More sharing options...
billwoodmason Posted May 9, 2014 Share Posted May 9, 2014 Congrats !! Great to see your project is up and running well. I'm interested in your mods you've mentioned and would love to see some photos. Can you post some for us all to learn from. 1 Link to comment Share on other sites More sharing options...
Keenaviator Posted May 9, 2014 Author Share Posted May 9, 2014 Thanks Laurie,Good to see someone who understands and works to the basic principles. How 'bout some pics of the under cowl work? 15c ambient is fairly cool, sounds like southern highlands weather. It will be interesting to see what results you get on more extreme days. What's the vertical gauge mid panel? Do you plan to monitor all CHT's & EGT's? I'll put together some photos soon.... The outside temp at 2500' I guessed since it was 18 on the ground. I found today why it has been running so rich - I checked the main jet and found it was a 255, normally fitted to a 3300. That's why the fuel flow numbers have been more like those for a 3300, not a 2200. Anyway I was given a 235 main jet to try and it seems better. I'll get the 245 main and recommended needle and needle jet for this motor asap because I wouldn't be surprised if it is fitted with those for a 3300 as well. The CHT and oil temperatures remained the same with the smaller main jet. The engine is now due for its first head tension and tappet check. Think I'll now hold off on further flying until I can get my hands on the proper needle and jets. Regarding full monitoring, I'd really like to but probably at bit hard to get past the finance minister and the moment. For now I'll stick with monitoring the theoretical hottest and leanest cylinders and checking the colour of spark plugs. Regards, Laurie Link to comment Share on other sites More sharing options...
Keenaviator Posted May 9, 2014 Author Share Posted May 9, 2014 Thanks Laurie,What's the vertical gauge mid panel? It's a simple 'G' meter. No need for it really, had it lying around from my last project which ended up having a better one installed. Laurie Link to comment Share on other sites More sharing options...
alf jessup Posted May 9, 2014 Share Posted May 9, 2014 Nice Job Laurie, Good to see you getting it in the air and beginning to use it for what it was designed for, I guess I will catch up to you sometime at YWSL. Alf 1 1 Link to comment Share on other sites More sharing options...
Keenaviator Posted May 9, 2014 Author Share Posted May 9, 2014 Nice Job Laurie,Good to see you getting it in the air and beginning to use it for what it was designed for, I guess I will catch up to you sometime at YWSL. Alf Will do Alf. Weather permitting, I'll be back next Friday just after East Sale deactivates. Doing a mixture assessment with Daryl. Cheers, Laurie Link to comment Share on other sites More sharing options...
stevron Posted May 11, 2014 Share Posted May 11, 2014 Looks great Laurie how does it fly? Steve Link to comment Share on other sites More sharing options...
Keenaviator Posted May 11, 2014 Author Share Posted May 11, 2014 It's going pretty well Steve. First 5 hours flown have been good. Sorting out a rich mixture issue - it appears the engine came with very rich jetting (possibly for a 6 instead of a 4 cylinder). Anyway I've now got the recommended main and needle jets in and going to test it tomorrow. Laurie Link to comment Share on other sites More sharing options...
stevron Posted May 11, 2014 Share Posted May 11, 2014 Fantastic, I have been flying mine a bit, there is another ignition replacement bulletin on my plane , I do not think they will ever get it right , when you come over are you flying? Link to comment Share on other sites More sharing options...
Keenaviator Posted May 11, 2014 Author Share Posted May 11, 2014 Not yet mate, have to complete the first 25 hours. Will be on the bike again. Link to comment Share on other sites More sharing options...
Keenaviator Posted May 11, 2014 Author Share Posted May 11, 2014 Another video, this time with some slow flight and gliding. There is a typo - we climbed to 3600 ' not ". Link to comment Share on other sites More sharing options...
alf jessup Posted May 11, 2014 Share Posted May 11, 2014 Laurie, Good to see you and Mr Lappin having some quiet time together, bird glides real well by the looks of it. Alf 1 Link to comment Share on other sites More sharing options...
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