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Lynn Matteson
Joined: 10 Jan 2006
Posts: 2778
Location: Grass Lake, Michigan
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 Posted: Mon Aug 16, 2010 7:04 am Post subject: Propeller decision. |
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I've been asking folks on the YahooJabiru group about ground-
adjustable props, and came to a decision of sorts. Because some
Jabiru owners don't go there, I thought I'd share some figures with
this group, and maybe get some interest going about props, etc.
Here's the post that I made at Yahoo Jabiru:
*************************
Thanks to all who offered suggestions regarding the ground adjustable
prop. After reading and digesting the comments, and flying a couple
of times with my chopped-down 55.5" x 46" wood prop, I think I've
concluded that if I could match the performance of this bastardized
prop with a fixed pitch prop of a normal shape (after cutting, the
ends of my blades are blunt...no rounding-off was done), I'd go with
it. What I mean is, if I could get Sensenich to use the numbers that
seem to give me good performance....the 55.5" x 46"....and make a
prop of say, 62" x 40 or 42", I'd do it. I'll call them and see
what they suggest. This might be a good time to visit the Prince prop
factory, as they are within 100 miles. I just don't like the 16-week
wait, or the 16-days wait at 50% more money. : (
The ground adjustable thing seems to be an area with problems, as far
as the present is concerned, so I think I'll stay away from them.
Here's the comparison between the 62x46 and the 55.5x46.....with the
62, I get about 2810-2840 rpm climbout ((at) about 6.4 gph fuel flow),
and the 55.5 gives me 3000-3040 rpm, using 7.0 gph fuel flow.
According to the fuel use, the higher rpm's are giving me more
horsepower during climbout. I checked this morning, and my speed at
WOT straight and level, going nearly across the wind (northbound) was
101 mph at 3210 rpm, and 123 mph at 3240 rpm going southbound. The
wind was reported at 3000' to be 281° (at) 29 kts. So the shorter prop
gives me the desired rpm's, but that's not the way to do it,
according to the theories that I've read and heard.
I only flew for a little while, but during that time, the fuel usage
was comparable to what I've been seeing....around 2.9 to 3.2 gph
(running lean of peak EGT), but the rpm was higher. I saw no change
in EGT's as a result of letting the rpm wind up a bit.
**************************
The reason for wanting a different prop came about after I flew into
a moderately hard rain and it etched/blasted the leading edge of my
prop pretty badly.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Sensenich 62"x46" Wood (summer)
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying...1040+ hrs (since 3-27-2006)
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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_________________
Lynn
Kitfox IV-Jabiru 2200
N369LM |
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naftalih(at)hotmail.com
Guest
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| Posted: Tue Aug 17, 2010 2:05 am Post subject: Propeller decision. |
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Hi Lynn,
Did you hear about the french DUC Swirl ground adjustable? the X-Air is using it with the JAB 2200.
> From: lynnmatt(at)jps.net
[quote] Subject: Propeller decision.
Date: Mon, 16 Aug 2010 11:03:30 -0400
To: jabiruengine-list(at)matronics.com
--> JabiruEngine-List message posted by: Lynn Matteson <lynnmatt(at)jps.net>
I've been asking folks on the YahooJabiru group about ground-
adjustable props, and came to a decision of sorts. Because some
Jabiru owners don't go there, I thought I'd share some figures with
this group, and maybe get some interest going about props, etc.
Here's the post that I made at Yahoo Jabiru:
*************************
Thanks to all who offered suggestions regarding the ground adjustable
prop. After reading and digesting the comments, and flying a couple
of times with my chopped-down 55.5" x 46" wood prop, I think I've
concluded that if I could match the performance of this bastardized
prop with a fixed pitch prop of a normal shape (after cutting, the
ends of my blades are blunt...no rounding-off was done), I'd go with
it. What I mean is, if I could get Sensenich to use the numbers that
seem to give me good performance....the 55.5" x 46"....and make a
prop of say, 62" x 40 or 42", I'd do it. I'll call them and see
what they suggest. This might be a good time to visit the Prince prop
factory, as they are within 100 miles. I just don't like the 16-week
wait, or the 16-days wait at 50% more money. : (
The ground adjustable thing seems to be an area with problems, as far
as the present is concerned, so I think I'll stay away from them.
Here's the comparison between the 62x46 and the 55.5x46.....with the
62, I get about 2810-2840 rpm climbout ((at) about 6.4 gph fuel flow),
and the 55.5 gives me 3000-3040 rpm, using 7.0 gph fuel flow.
According to the fuel use, the higher rpm's are giving me more
horsepower during climbout. I checked this morning, and my speed at
WOT straight and level, going nearly across the wind (northbound) was
101 mph at 3210 rpm, and 123 mph at 3240 rpm going southbound. The
wind was reported at 3000' to be 281° (at) 29 kts. So the shorter prop
gives me the desired rpm's, but that's not the way to do it,
according to the theories that I've read and heard.
I only flew for a little while, but during that time, the fuel usage
was comparable to what I've been seeing....around 2.9 to 3.2 gph
(running lean of peak EGT), but the rpm was higher. I saw no change
in EGT's as a result of letting the rpm wind up a bit.
**************************
The reason for wanting a different prop came about after I flew into
a moderately hard rain and it etched/blasted the leading edge of my
prop pretty badly.
Lynn Matteson
Kitfox IV Speedster, taildragger
Jabiru 2200, #2062
Sensenich 62"x46" Wood (summer)
Electroair direct-fire ignition system
Rotec TBI-40 injection
Status: flying...1040+ hrs (since 3-27-2006)
> _====================
| | - The Matronics JabiruEngine-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?JabiruEngine-List |
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