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rjdaugh
Joined: 30 Aug 2006 Posts: 195
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Posted: Thu Mar 22, 2007 6:06 pm Post subject: Best prop was: Fuel consumption based on gallons per hour |
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Geeze, you are going to wheedle all the details out of me before I get done testing.
OK. Plane is series 5 with Series 7 firewall forward. Grove gear and big tires. 776 lb empty. Engine is 912S. Old prop is 70” Powerfin “F”, 3 blade. It was 72” but the factory cut 1” off each blade for me to make it faster. Cutting off the 1” did make it faster. But not enough.
I tried a friend’s Warpdrive and Wow! His was a straight tip. I immediately ordered a taper tip 70” 3 blade warpdrive. New airplane! I am still playing with pitch so some numbers are fuzzy….
I used to think that with a ground adjustable prop, you just set the pitch to what you want – cruise or good take off and climb. But it is far from that simple.
I will try a table.
Prop Pitched for: Static rpm Airspeed at 5500 rpm Indicated airspeed at redline (5800 rpm
72” PF reasonable t/o 5200 80 mph 85 mph
72” PF very slow t/o 4800 88 mph 95 mph
70” PF Reasonable t/o 5200 86 mph 92 mph
70” PF Very slow t/o 4900 94 mph 100 mph
70” WD reasonable t/o 5300 106 mph 115 mph
70” WD very slow t/o 5000 118 mph Can’t get there!
My plane has big tires but with wide open throttle and lots of pitch the warp drive gets me something on the order of 122 mph indicated. About 130 on the GPS. And I can’t over rev the engine in level flight.
So there! If there is error in the numbers (beyond my normal errors that is), it is you fault for not letting me finish testing. But it is a new plane with the Warpdrive prop. Getting off the ground without a Cessna like ground role is important to me so I will probably settle on a 5500 rpm cruise of about 108 – 110.
Randy
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From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of fox5flyer
Sent: Wednesday, March 21, 2007 3:29 PM
To: kitfox-list(at)matronics.com
Subject: Re: Best prop was: Fuel consumption based on gallons per hour
OK now, no secrets my friend. What is that prop that you're experimenting with and what was the one you were using previously?
Deke
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_________________ Randy
Kitfox 5/7 912S
Black Hills, South Dakota |
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fox5flyer(at)idealwifi.ne Guest
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Posted: Fri Mar 23, 2007 4:14 am Post subject: Best prop was: Fuel consumption based on gallons per hour |
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Great report Randy. It's good to see hard data to help us all make future decisions. OK, no more questions from me until your testing is complete!
Good luck.
Deke
do not archive
[quote] ---
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Bob
Joined: 24 Oct 2006 Posts: 89 Location: Damascus, Maryland, USA
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Posted: Fri Mar 23, 2007 4:42 am Post subject: Re: Best prop was: Fuel consumption based on gallons per h |
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Hi Randy -
I'm building an early 5 and it looks like you've done what I'm trying to get to. Great job on keeping the weight down! Being an engineer, I really appreciate the data and hope that you don't mind my plotting it. That really IS a huge difference between props!
Bob
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ann7ddt(at)msn.com Guest
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Posted: Fri Mar 23, 2007 4:43 am Post subject: Best prop was: Fuel consumption based on gallons per hour |
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<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> [quote] You don't know how helpful you have been, all this prop stuff in the ads doesn't mean much to me w/o figures like yours, ...so Ill bet you have done some gallons/per hr checks also, ...I'll bet none were over 51/2 per hr, ...right...thks Dean
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lcfitt(at)sbcglobal.net Guest
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Posted: Fri Mar 23, 2007 6:39 am Post subject: Best prop was: Fuel consumption based on gallons per hour |
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Randy,
This is good info. It correlates exactly with the PowerFin performance my
friends had on their Model IVs. Although I flew along side them for
numerous hours our performence data was anecdotal at best. They also did
the 1 inch cut at the ends and it helped a bit as you report. Do you have
climb figures and I am sure the actual prop pitch would be of interest if
you have that.
Lowell
do not archive
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avtar412
Joined: 15 Nov 2006 Posts: 22 Location: New Zealand
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Posted: Sat Mar 24, 2007 1:00 am Post subject: Re: Best prop was: Fuel consumption based on gallons per h |
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I have a 72" WD on Kitfox 5 (heavy at 335kgs) and get 100kts and 1700fpm climb with just me on board (70kgs). Subaru EA81 Turbo. I'm a sure fan of WD
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kitfoxmike
Joined: 05 Dec 2006 Posts: 373
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Posted: Sat Mar 24, 2007 12:13 pm Post subject: Re: Best prop was: Fuel consumption based on gallons per h |
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I would like to see a comparison between the WD and the IVO.
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rjdaugh
Joined: 30 Aug 2006 Posts: 195
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Posted: Tue Mar 27, 2007 7:30 am Post subject: Best prop was: Fuel consumption based on gallons per hour |
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Lowell,
It was your recounting of their experience that finally pushed me over the
edge to shorten the Powerfin prop. I don't have good climb data. I just
can't seem to get stabilized long enough to get the data.
It took me a while to dig out the pitch data. I align the blades with a
home made laser tool because I feel it is more precise, and don't usually
measure the actual angle. The Powerfin data is from their feeler gauge
data. The Warp Drive is measured at the tip of the prop with the Warp Drive
protractor. I tried to add the pitch to the table in old post below but
will also summarize.
72" PF climb pitch 11.3 degrees, Cruise 12.5 deg
70" PF climb 12.5, cruise 13.2
70 Warp climb 12.6, cruise 14.75
I plan to go to about 13 degrees on the Warp Drive prop as a compromise, but
close to the best climb area. I think that this will be a pitch that does
not allow the engine to over rev in level but come up close to redline.
Randy
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_________________ Randy
Kitfox 5/7 912S
Black Hills, South Dakota |
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