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  #11  
Old 06-23-2011, 09:11 PM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
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Location: Brisbane Qld. Aust.
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Old Wives Tales.........aint they great. Glad to see some are gradually being eroded. Except some of the CPL's coming out of flying schools around here

I generally push the throttle forward and leave it there until I reduce power in the circuit or for any ATC reason.

RPM is set at TOC and mixture does the rest.
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  #12  
Old 06-23-2011, 11:13 PM
xblueh2o xblueh2o is offline
 
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Location: SF East Bay
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I had not heard of a prohibition on running over square in radial engines aside from power limits or severe over square. There are lots of caution, notes and limitations on running under square (more RPM than MAP) found throughout the old operating handbooks I have read. Having the prop drive the engine in a radial is a really good way to chew up the master rod bearing in a big hurry.

None of this translates to opposed engines.
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  #13  
Old 06-23-2011, 11:47 PM
ao.frog ao.frog is offline
 
Join Date: Sep 2006
Location: Manstad, Norway
Posts: 866
Default Thanks guys...

.... I'm learning something new everyday in this business!
Seems like I have a whole new line of powersettings to try out now. (I'll check the engine and prop-manual first ofcourse)
It'll be interesting to try out WOT and lower RPM when flying at cruise at my favorite cruise-powersetting and altitudes (55% and 5-10.000')

Paul: even though most European countries use metric by now, here's how it is when it comes to planes in the majority of the Euoropean countries:

Altitude: feet
Speed: knots (mph is for cars and NOT planes )
Altimeter: millibars
MAP: inches
Temp: (OAT,EGT/CHT etc) Celcius
Lenghts (wingspan etc) meter and centimeter
Lengths of a flown distance: NM (SM is for cars and NOT planes )
Quantity: litres
FF: litres per hour
Weight: kilos and tons
Pressure: (oil/fuel) PSI
Pressure: (tires) PSI or BAR
ATC language: english and the local language

These are just some units I remember right now, so there might be others that I've forgotten.
There are also some variations to these units in some countries.

Confusing...? naah... it's just something to get used to...
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Last edited by ao.frog : 06-24-2011 at 12:59 AM.
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  #14  
Old 06-24-2011, 04:52 AM
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pierre smith pierre smith is offline
 
Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
Default Good question Alf..

You are/were mostly a jet guy but my old Pratt and Whitney 1340 cu. in. radial was placarded for 36"/2200 RPM at take-off, in my Air Tractor crop-dusting airplane.

Once level and during work in the field, it stayed at 30" and 2,000 RPM...ALL DAY, for several years, until overhaul!

My RV-10 with its IO-540, climbs at WOT 28"+ and 2500 RPM.

Best,
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  #15  
Old 06-24-2011, 10:41 AM
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Flyfalcons Flyfalcons is offline
 
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Location: Bonney Lake, WA
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Quote:
Originally Posted by xblueh2o View Post
I had not heard of a prohibition on running over square in radial engines aside from power limits or severe over square. There are lots of caution, notes and limitations on running under square (more RPM than MAP) found throughout the old operating handbooks I have read. Having the prop drive the engine in a radial is a really good way to chew up the master rod bearing in a big hurry.

None of this translates to opposed engines.
Heck if I were to fly undersquare in the Beaver, I wouldn't be able to maintain altitude!

36.5"/2300rpm max 1 minute
33"/2200rpm max continuous
30"/2000rpm normal climb
28"/1850rpm cruise
(R-985)
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  #16  
Old 06-24-2011, 12:16 PM
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Mel Mel is offline
 
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Quote:
Originally Posted by Flyfalcons View Post
Heck if I were to fly undersquare in the Beaver, I wouldn't be able to maintain altitude!
I think the original post was meant to relate to normally aspirated engines.
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  #17  
Old 06-24-2011, 12:19 PM
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Flybuddy2 Flybuddy2 is offline
 
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Location: Fort Myers
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Oversquare is fine, a good rule of thumb in a normally aspirated is to try to keep it within 4 over during cruise (example-- 27" and 2300rpm).
Consider that many fixed pitch setups will exceed even this on takeoff roll.
Lindbergh used to teach oversquare operations to military pilots for fuel efficiency.
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  #18  
Old 06-24-2011, 03:00 PM
prporter prporter is offline
 
Join Date: Jul 2006
Location: Vul, VA
Posts: 316
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I run my Duke on take off at 41", and 2800 rpm. My guess is that this would be over square. TIO 541, 380 HP. Throttle back to 38"/2750, and eventually to 30"/2700.

Last edited by prporter : 06-24-2011 at 07:13 PM.
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  #19  
Old 06-24-2011, 05:16 PM
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Flybuddy2 Flybuddy2 is offline
 
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Location: Fort Myers
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Quote:
Originally Posted by pierre smith View Post
You are/were mostly a jet guy but my old Pratt and Whitney 1340 cu. in. radial was placarded for 36"/2200 RPM at take-off, in my Air Tractor crop-dusting airplane.

Once level and during work in the field, it stayed at 30" and 2,000 RPM...ALL DAY, for several years, until overhaul!

My RV-10 with its IO-540, climbs at WOT 28"+ and 2500 RPM.

Best,
Pierre, the 1830s in the DC3s I flew were 48" and 2700 on takeoff. Cruise was similar at 30" and 2050. They limited them to 48" because of the unavailability of higher octane fuel. I never flew one with 115/130 but I believe it was something like 54" allowed.
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  #20  
Old 06-24-2011, 05:46 PM
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osxuser osxuser is offline
 
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Location: Pasadena CA
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Best speed in the C177 was always WOT and 2400RPM... O-360A1A, three blade hartzell.
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