Carb heat on non-fuel injected engines helps keep the venturi from being plugged up by ice. This can happen with air temps as high as 100F and relative humidity of +50%. This normally happens when you are about to land or make a long decent. When you bring the RPM's out of the green arc on a fixed pitch prop aircraft you should either turn carb heat on for the duration or with Piper aircraft, turn it on an make sure the engine doesn't run rough. If it does, leave it on and let it burn off the ice, then the engine should run more smoothly again.
There are many descriptions of how to use Carb heat in the POH's and on the web. Ryan -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Arnt Karlsen Sent: Wednesday, March 05, 2003 9:42 PM To: [EMAIL PROTECTED] Subject: Re: [Flightgear-devel] Change to default aircraft On Wed, 5 Mar 2003 21:33:35 -0500, David Megginson <[EMAIL PROTECTED]> wrote in message <[EMAIL PROTECTED]>: > Arnt Karlsen writes: > > > ..heh, and you the emacs'er balance that by running lean-of-peak? > > ;-) > > I am afraid that I do no understand your insinuation. If I'm on the > side of the angels with one, should I not be on their side with both? .. ;-) > > ..how far back can you drag it before it starts running rough? > > Without carb heat, I can lean back to between 65% and 75% power, > depending on the day and how long the engine has been running. With > carb heat on in cruise, I can pull it back much farther, probably > right to cutoff if I were so inclined. > > The nice thing is that I have my Piper POH for backup: > > For Best Economy cruise, a simplified leaning procedure which > consistently allows accurate achievement of best engine efficiency > has been developed. Best Economy Cruise performance is obtained with > the throttle fully open. To obtain a desired cruise power setting, > set the throttle and mixture control full forward, taking care not > to exceed the engine speed limitation, then begin leaning the > mixture. The RPM will increase slightly but will then begin to > decrease. Continue leaning until the desired cruise engine RPM is > reached. This will provide best fuel economy and maximum miles per > gallon for a given power setting. > > It's easy to do this with a fixed-pitch prop, since the tach gives a > direct indication of power setting at any given density altitude. ..I should have asked: how far back/down of peak temp? Carb heat helps you down the temperatures on leaning way back, how far down? -- ..med vennlig hilsen = with Kind Regards from Arnt... ;-) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
