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01-30-2007, 08:21 AM
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Join Date: Jan 2007
Location: Bountiful, Utah
Posts: 161
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I'm not particularly comfortable with the idea of over revving long-stroke big-bore reciprocating engines for long periods. High rpm adds a LOT of excessive internal stress on the crankshaft and oil-supported bearings, which has to add to wear rates. It also undoubtedly adds a lot of extra heat into an already marginal cooling (and lubrication) system.
I AM quite interested in Paul Epps' unique propeller design- I just wish it were available and tested a bit more in our "normal" aircraft. IMHO, it has the potential to be the next quantum leap in a very innovation-adverse market.
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01-30-2007, 08:55 AM
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Banned
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Join Date: May 2006
Location: Phoenix, Az
Posts: 920
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Sensenich for Me
I was planning on an MT electric 3 blade for my 9 until I saw the 500 hr TBO. Now I'm thinking that any piece of equipment with a TBO that low
is developmental, and not anything I want on my airplane. Must be having blade or hub problems to have such a low life limit. I ordered a Sensenich FP.
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01-30-2007, 09:05 AM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Quote:
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Originally Posted by osxuser
Lycoming is tested for certification at 100% power (at least the ones we fly), BUT that doesn't mean ANYTHING about TBO. I don't think i'd expect a lycoming that was continuously run at 100% power to make 2000hr's. Lycoming itself says in it's care info to use 75% or less power for best engine life...
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Negative on the 75%.
From Lycoming Flyer Key Reprints (in bold print, item 9, page 38)
...for maximum service life maintain 65% or less rated power.....cht 400 or less.....oil temp 165-220.
These engines will routinely go beyond TBO, I've seen an Aztec engine at 2600 hours running just fine, (before 135 mandated overhaul at TBO) but for sure not at 100% and probably not at 75% either.
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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01-30-2007, 11:36 AM
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Join Date: Aug 2005
Location: Houston
Posts: 17
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$
So what is the cost difference? After reading this thread I have seen #'s thrown around from 2k to 10k...Could someone post some real world #'s on the costs? How much MORE am I going to spend by getting a CS?
Thanks,
Mark
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01-30-2007, 11:57 AM
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Join Date: May 2005
Posts: 165
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C/S V FP
2005 prices. governor 1050.00, cable bracket, 13.20, cable 10.71, prop new Hartzell for 320 360 Lyc. 5220.00. total $6293.91. Fixed pitch Sensenich for same $1935.00. $4358.91 difference.
Prices have gone up a bit.
I fly a RV9-A with a C/S, don't know if it is worth it or not but I love it. 
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01-30-2007, 12:08 PM
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Join Date: Jan 2005
Posts: 3,646
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Quote:
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Originally Posted by markpsmith
So what is the cost difference? After reading this thread I have seen #'s thrown around from 2k to 10k...Could someone post some real world #'s on the costs? How much MORE am I going to spend by getting a CS?
Thanks,
Mark
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All depends on which props you are comparing. If you buy from Van's your lowest cost options are Hartzell c.s. and Sensenich fixed pitch:
The basic Hartzell constant speed costs $6090, plus you will need a governor for $1100. Total constant speed = $7190. If you buy a Sensenich fixed pitch, that cost is only $2060. No governor needed. Difference between C.S. ($7190) and Fixed pitch ($2060) = $5130 more for the c.s. at a minimum.
A couple other things to think about :
1. for all of their advantages, the c.s. require more maintenance (= $$).
2. you can get a Catto 2-blade fixed pitch for $1200 which would increase the savings over c.s. even more.
__________________
Steve M.
Ellensburg WA
RV-9 Flying, 0-320, Catto
Donation reminder: Jan. 2021
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01-30-2007, 01:15 PM
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Join Date: Jan 2005
Location: NC25
Posts: 3,508
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Quote:
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Originally Posted by David-aviator
Negative on the 75%.
From Lycoming Flyer Key Reprints (in bold print, item 9, page 38)
...for maximum service life maintain 65% or less rated power.....cht 400 or less.....oil temp 165-220.
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A link to the article is at: http://www.lycoming.textron.com/main...TradeOffs.html
__________________
Gary A. Sobek
NC25 RV-6 Flying
3,400+ hours
Where is N157GS
Building RV-8 S/N: 80012
To most people, the sky is the limit.
To those who love aviation, the sky is home.
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01-30-2007, 03:23 PM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Quote:
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Originally Posted by RV6_flyer
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Gary, the information I was referring to is located here:
http://www.lycoming.textron.com/main...gEngines.html#
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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04-02-2007, 06:31 PM
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Join Date: Jan 2005
Location: Kamloops, BC, Canada
Posts: 163
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CS vs Fixed
I'm surprised this debate hasn't been done yet.
Im building an RV-8
I've decided on an IO-360 and now I need to decide on the prop. I haven?t decided on the exact IO-360 engine yet but I will be buying new from Aero Sport. Probably the non-counter weight engine with high compression pistons and electronic ignition. I?ll pay the extra $300 and get a constant speed crank regardless of whether I go constant speed or fixed pitch.
I?ve heard and read that above 200hp you really should have a constant speed prop. But an IO-360 with high compression pistons will be just slightly below that boarder line. I think somewhere around 190hp.
What are the pros and cons on a constant speed verses fixed pitch for this size of engine?
What sort of performance gains verses weight loses and costs am I going to experience?
My main mission will probably be long x-countries.
Last edited by kevinsky18 : 04-02-2007 at 06:40 PM.
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04-02-2007, 07:21 PM
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Join Date: May 2005
Location: Santa Barbara, CA
Posts: 1,324
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It has come up. Run a search, I got 153 hits.
The bottom line is more weight, cost, and performance (CS) vs less cost, weight and performance with the fixed prop. Before the debate starts anew, you can engineer a fixed prop to climb or cruise with a CS but not both.
John Clark
RV8 N18U "Sunshine"
IO360/CS
KSBA
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