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Knicholas2(at)aol.com
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 Posted: Tue Dec 02, 2008 11:39 am Post subject: Should I re-pitch my prop? |
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My RV9 has the recommended fix pitch prop on my 150 HP Lycoming 0-320 engine. It has plenty of power and climb but I would like a little more speed than the current 135-140 kt cruise.
I am considering having the prop re-pitched for more speed.
What do others think? Good idea or bad? How much more should I have the pitch increased?
Thanks in advance for input.
Kim Nicholas
RV9A
Auburn, WA
Life should be ea&icid=aolcom40vanity&ncid=emlcntaolcom00000002">Try the NEW AOL.com.
[quote][b]
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kahuna
Joined: 02 Feb 2007
Posts: 93
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| Posted: Tue Dec 02, 2008 12:08 pm Post subject: Should I re-pitch my prop? |
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we need more info.
current prop type, manufacturer size and pitch.
current WOT RPM at 8k'
Current cruise speed and RPM.
Current climb RPM, IAS and FPM altitude start
Mike
[img]cid:1__=0ABBFF80DFFD9E5B8f9e8a93df938(at)us.ibm.com[/img]Knicholas2---12/02/2008 02:54:29 PM---
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To
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rv-list(at)matronics.com [img]cid:3__=0ABBFF80DFFD9E5B8f9e8a93df938(at)us.ibm.com[/img]
cc
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Subject
[img]cid:3__=0ABBFF80DFFD9E5B8f9e8a93df938(at)us.ibm.com[/img]
Should I re-pitch my prop? [img]cid:3__=0ABBFF80DFFD9E5B8f9e8a93df938(at)us.ibm.com[/img][img]cid:3__=0ABBFF80DFFD9E5B8f9e8a93df938(at)us.ibm.com[/img]
My RV9 has the recommended fix pitch prop on my 150 HP Lycoming 0-320 engine. It has plenty of power and climb but I would like a little more speed than the current 135-140 kt cruise.
I am considering having the prop re-pitched for more speed.
What do others think? Good idea or bad? How much more should I have the pitch increased?
Thanks in advance for input.
Kim Nicholas
RV9A
Auburn, WA
Life should be ea&icid=aolcom40vanity&ncid=emlcntaolcom00000002">Try the NEW AOL.com.
=====================================
ion">[b]http://www.matronics.com/contribution
=====================================
?RV-List">[b]http://www.matronics.com/Navigator?RV-List
=====================================
u>http://forums.matronics.com[/u]
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wdleonard(at)gmail.com
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| Posted: Tue Dec 02, 2008 12:20 pm Post subject: Should I re-pitch my prop? |
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That all depends on what RPM you are showing in climb and cruise and how much throttle you have available in cruise.
You are bounded by 2 extremes: the ultimate climb prop, and the ultimate cruise prop.
The ultimate climb prop will achieve full rated engine RPM in climb (at full throttle) but you will have to throttle back significantly in cruise to avoid exceeding redline.
The ultimate cruise prop will achieve full rated engine RPM in level flight and full throttle but your climbout will be at less than full RPM (therefore, less than max power). You could actually go beyond cruise prop and have a 'descent prop' where you can actually descend slightly at full power and not exceed redline RPM. That will decrease your max cruise speed somewhat (and really hurt climb rate) but at least full throttle cruise will be at a more comfortable economy cruise RPM.
Where you fall in that range is a matter of personal preference. I actually have 'descent prop' and really like it, but my turbo allows me to make up for what would otherwise be poor climb performance.
For the specifics of how much pitch change will take you from one type of prop to the next, you need to talk to the maker of the prop and your re-pitching shop.
David Leonard
Turbo Rotary RV-6
On Tue, Dec 2, 2008 at 11:38 AM, <Knicholas2(at)aol.com (Knicholas2(at)aol.com)> wrote:
| Quote: |
My RV9 has the recommended fix pitch prop on my 150 HP Lycoming 0-320 engine. It has plenty of power and climb but I would like a little more speed than the current 135-140 kt cruise.
I am considering having the prop re-pitched for more speed.
What do others think? Good idea or bad? How much more should I have the pitch increased?
Thanks in advance for input.
Kim Nicholas
RV9A
Auburn, WA
Life should be ea&icid=aolcom40vanity&ncid=emlcntaolcom00000002">Try the NEW AOL.com.
|
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[quote][b]
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wmjack1(at)t3cs.net
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| Posted: Tue Dec 02, 2008 1:56 pm Post subject: Should I re-pitch my prop? |
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If memory serves me right, didn’t Van’s recommend against re-pitching metal props taken from spam-cans? I poked around a bit and found the following on Van’s site.
“The Sensenich metal propellers we sell were developed specifically for the RV series and are the ONLY fixed pitch metal propellers approved by Van's Aircraft Inc. for use on RV aircraft. “
“Propellers from production aircraft are not suitable, and unfortunate experience has shown that modified production propellers can fail without warning with deadly consequences.”
Full article can be found at:
http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1228254533-26-123&browse=props&product=sen-prop
Jack Hilditch
RV-9A ( R ) project
Manchester, CT
From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of David Leonard
Sent: Tuesday, December 02, 2008 3:20 PM
To: rv-list(at)matronics.com
Subject: Re: Should I re-pitch my prop?
That all depends on what RPM you are showing in climb and cruise and how much throttle you have available in cruise.
You are bounded by 2 extremes: the ultimate climb prop, and the ultimate cruise prop.
The ultimate climb prop will achieve full rated engine RPM in climb (at full throttle) but you will have to throttle back significantly in cruise to avoid exceeding redline.
The ultimate cruise prop will achieve full rated engine RPM in level flight and full throttle but your climbout will be at less than full RPM (therefore, less than max power). You could actually go beyond cruise prop and have a 'descent prop' where you can actually descend slightly at full power and not exceed redline RPM. That will decrease your max cruise speed somewhat (and really hurt climb rate) but at least full throttle cruise will be at a more comfortable economy cruise RPM.
Where you fall in that range is a matter of personal preference. I actually have 'descent prop' and really like it, but my turbo allows me to make up for what would otherwise be poor climb performance.
For the specifics of how much pitch change will take you from one type of prop to the next, you need to talk to the maker of the prop and your re-pitching shop.
David Leonard
Turbo Rotary RV-6
On Tue, Dec 2, 2008 at 11:38 AM, <Knicholas2(at)aol.com (Knicholas2(at)aol.com)> wrote:
My RV9 has the recommended fix pitch prop on my 150 HP Lycoming 0-320 engine. It has plenty of power and climb but I would like a little more speed than the current 135-140 kt cruise.
I am considering having the prop re-pitched for more speed.
What do others think? Good idea or bad? How much more should I have the pitch increased?
Thanks in advance for input.
Kim Nicholas
RV9A
Auburn, WA
Life should be ea&icid=aolcom40vanity&ncid=emlcntaolcom00000002">Try the NEW AOL.com.
- 0123456789012345
[quote][b]
| | - The Matronics RV-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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pitts_pilot(at)bellsouth.
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| Posted: Tue Dec 02, 2008 2:12 pm Post subject: Should I re-pitch my prop? |
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From a practical standpoint there shouldn't be any reason why a 'spam
can' prop from the same engine won't work on Van's airplanes. What he
says about failures is true and should be part of your decision on where
your prop comes from. A prop can only be pitched and re-pitched so many
inches total, and then it's junk. When a prop is repitched, the change
is stamped on the hub. Or at least it should be. I think this is the
root of Van's warning. Documentation can be lacking so be careful.
Without an accurate prop log, which wasn't 'required' when I began my
road to the poorhouse, you can't be sure of the hours it has on it,
whether it was straightened after a slight prop strike or not ..... see
where I'm going on this???
Van likes Sensenich props, and that's the only ones he's 'tested' on his
birds .... hence the word 'approved' in his warning. A McCauley may be
better or worse than the Sensenich .... only testing would tell.
Linn
Jack Hilditch wrote:
| Quote: |
If memory serves me right, didn’t Van’s recommend against re-pitching
metal props taken from spam-cans? I poked around a bit and found the
following on Van’s site.
“The Sensenich metal propellers we sell were developed specifically
for the RV series and are the ONLY fixed pitch metal propellers
approved by Van's Aircraft Inc. for use on RV aircraft. “
“Propellers from production aircraft are not suitable, and unfortunate
experience has shown that modified production propellers can fail
without warning with deadly consequences.”
Full article can be found at:
http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1228254533-26-123&browse=props&product=sen-prop
<http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1228254533-26-123&browse=props&product=sen-prop>
Jack Hilditch
RV-9A ( R ) project
Manchester, CT
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sbuc(at)hiwaay.net
Guest
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| Posted: Tue Dec 02, 2008 5:41 pm Post subject: Should I re-pitch my prop? |
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linn Walters wrote:
| Quote: |
From a practical standpoint there shouldn't be any reason why a 'spam
can' prop from the same engine won't work on Van's airplanes.
<snip>
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The reason very few fixed-pitch "spam can props" are practical for an RV
is because the speedy RV needs far more pitch than a C172 or similar
aircraft. The RV Sensenich props are steeply pitched, so much so that
special templates are required for a prop shop to measure the pitch. The
"big lever" method of repitching an RV prop is very difficult due to the
thick blade root. A return to Sensenich for repitch on their hydraulic
rig is the best way to go for our props.
The gory details of the repitching of my Sensenich by a local prop shop:
http://thervjournal.com/fairings.htm#repitch
Sam Buchanan
| | - The Matronics RV-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?RV-List |
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