Heloman Posted June 13, 2017 Report Share Posted June 13, 2017 When I put the LAsar Cowl on my 68c with fixed Cowl flaps I immediately noticed higher takeoff CHTs. I rarely ever broke 400 on any cylinder according to the JPI before, no matter what i did, and I normally did short field takeoffs. Now, I routinely will go a little over 400 while working to keep temps down, both by not using short field technique, and by reducing power much earlier then I did before. Cruise temps do seem to be noticeably down. When I put the LASAR cowl on I also sealed up the doghouse baffling much better then it had been before. I sealed around the areas where the engine mounts pass through the baffling. And using a flashlight, I put foil tape everywhere I could see light coming through while looking through the cowl inlet. Is it possible that the new "inlet to fixed flap ratio" just isn't optimal for takeoff? If so, then I shouldn't be the first to experience this. I'm wondering what others with fixed flaps think about this? As an experiment, I left off the foil tape recently when I had the doghouse cover off ( which leaves a thin air gap all around the top cover the thickness of the tinnermen nuts), flying today it seemed to make no change, so I'm inclined to blame the higher takeoff temps on the cowl mod. Anyone have any thoughts on this? Sent from my iPad using Tapatalk Quote Link to comment Share on other sites More sharing options...
carusoam Posted June 13, 2017 Report Share Posted June 13, 2017 Do you know how large the gap is for your fixed flaps? I'm not sure what it is supposed to be. Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Andy95W Posted June 13, 2017 Report Share Posted June 13, 2017 Unless you're trying to clear trees, you're better off not using any sort of short field technique once you climb above a hundred feet or so. 120 mph will give about the same rate of climb as 95, albeit at a much worse angle- but your CHTs will be much cooler. 2 Quote Link to comment Share on other sites More sharing options...
Hank Posted June 13, 2017 Report Share Posted June 13, 2017 I routinely climb at Vy (100 mph - altitude) without CHT problems except sometimes in the summer. I do have the guppy mouth closure. Resurrecting my doghouse improved my cruise speed 10-12 mph, but I didn't notice much effect on CHT. Then again, I also leave all three levers full forward; when I remember, I lean to Target EGT. There is no "power reduction" until after I level off and accelerate, and then it's just to set cruise power and lean. Quote Link to comment Share on other sites More sharing options...
Heloman Posted June 14, 2017 Author Report Share Posted June 14, 2017 Do you know how large the gap is for your fixed flaps? I'm not sure what it is supposed to be. Best regards, -a- Looks factory to me, no additional drilled holes. Sent from my iPad using Tapatalk Quote Link to comment Share on other sites More sharing options...
Schinderhannes Posted June 15, 2017 Report Share Posted June 15, 2017 Check the "December 2016 M20C (fixed) cowl flaps opening" thread and you will find a series of pictures showing the cowl opening of M20c's with fixed cowl flaps. Your cowl flaps opening is significantly larger than most of the fleet. 1 Quote Link to comment Share on other sites More sharing options...
Heloman Posted June 15, 2017 Author Report Share Posted June 15, 2017 12 hours ago, N9495V said: Check the "December 2016 M20C (fixed) cowl flaps opening" thread and you will find a series of pictures showing the cowl opening of M20c's with fixed cowl flaps. Your cowl flaps opening is significantly larger than most of the fleet. Wow, that's interesting. Quote Link to comment Share on other sites More sharing options...
jrwilson Posted June 15, 2017 Report Share Posted June 15, 2017 21 hours ago, N9495V said: Check the "December 2016 M20C (fixed) cowl flaps opening" thread and you will find a series of pictures showing the cowl opening of M20c's with fixed cowl flaps. Your cowl flaps opening is significantly larger than most of the fleet. Weird, I was thinking his cowl flap opening looked small compared to my old 20C... Quote Link to comment Share on other sites More sharing options...
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