With the engine running at idle the challenge is to determine if you are producing thrust or drag. The CAFE association uses a sensor on the engine to determine where the "zero thrust point" is by measuring the fore and aft movement of the crankshaft. If they are producing thrust the crank pulls forward slightly, if they are producing drag the crank moves back slightly. By using the sensor they can get a reasonable determination of the "zero thrust point" on the engine and then accurately determine the planes real L/D.
Motorglider pilots are famous for setting their thrust for a minimal sink rate while soaring, they get fantastic L/D's using that approach. Denny ... --- "Kenneth B. Jones" <[email protected]> wrote: > Maybe this table will be easier to read. > > ----- Original Message ----- > From: "Kenneth B. Jones" <[email protected]> > To: "KRnet" <[email protected]> > Sent: Friday, June 17, 2005 7:32 AM > Subject: Re: KR> glide rato.. > > > > Perhaps the stopped prop is less drag because it's > stalled. > > > > Below is data taken from my flight test. My idle > setting was about 800 to > > 900 rpm, a little high, at the time. Speeds are > indicated knots. My > > plane stalls at about 50 knots indicated so I > didn't check the glide below > > 60 kts. Surely the ratio will start back the other > way before it stalls. > > I have a KR-2 with Diehl wings, 3 blade Warp drive > taper blade 58" prop > > set at 19.5 degrees at the tip, A65, empty weight > is 623 lbs., full fuel > > is 14 gal and I weigh about 180. > > > > Glide > > Speed Descent Distance Glide > > kts ft/min NM/1000 ft. > Ratio > > > > 60 400 2.50 > 15.18 > > 65 442.5 2.45 > 12.93 > > 70 525 2.22 > 11.73 > > 75 625 2.00 > 10.56 > > 80 750 1.78 > 9.39 > > 85 800 1.77 > 9.35 > > 90 900 1.67 > 8.80 > > 95 1100 1.44 > 7.60 > > 100 1500 1.11 > 5.87 > > > > > > BTW, Bill's 2.5 miles per 1000 ft altitude is a > glide ratio of 13.2 : 1 > > (if I calculated correctly). > > > > Ken Jones, [email protected] > > Sharonville, OH > > N5834, aka The Porkopolis Flying Pig > > > > ----- Original Message ----- > > From: "Barry Kruyssen" <[email protected]> > > To: "KRnet" <[email protected]> > > Sent: Thursday, June 16, 2005 6:31 PM > > Subject: Re: KR> what a day./ glide rato.. > > > > > >> > >> ----- Original Message ----- From: larry flesner > I doubt if a stopped > >> propeller is going to triple that number > >> > >> A stopped prop actually produces less drag, don't > know the reason but > >> have tried it in self launch gliders (without > feathering the prop) both > >> idling engine and stoped, there is noticeably > less drag when the prop was > >> stopped. Also it is better for the prop to stop > vertically so any > >> vortices from the prop don't upset the air flow > over the wing, so I'm > >> told but I couldn't tell the difference :-) > >> > >> regards > >> Barry Kruyssen > > > > > > > _______________________________________ > Search the KRnet Archives at > http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to > [email protected] > please see other KRnet info at > http://www.krnet.org/info.html > "I can train a monkey to wave an American flag. That does not make the monkey patriotic." Scott Ritter __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
