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  #1  
Old 11-27-2017, 06:26 PM
fbrewer fbrewer is offline
 
Join Date: Sep 2017
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Default What RPM for Takeoff

In my RV-6, when taking off from KGTU (789' msl), I get appropriate manifold pressure of 29+ inches (depending on barometric pressure), but I only get 2340 rpm.

The motor has a fixed pitch prop.

Is this rpm appropriate for takeoff?

We have an IO360

Last edited by fbrewer : 11-27-2017 at 06:59 PM.
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  #2  
Old 11-27-2017, 06:29 PM
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Sam Buchanan Sam Buchanan is online now
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Yes.
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  #3  
Old 11-28-2017, 05:31 AM
Simon Hitchen Simon Hitchen is offline
 
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Default Right on

I have the same engine and a Sensenich fixed pitch prop. The quoted static RPM is around 2150 which is bang on. As the speed increases and the load on the prop decreases you'll get an increase in RPM obviously.

But yeah that's right on.

Simon
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  #4  
Old 11-28-2017, 08:57 AM
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az_gila az_gila is offline
 
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Just checked one of my flights.

Carb version of O-360 with the metal Sensenich prop at 83" pitch -

2206 RPM static

2250 RPM accelerating through 25 kts on the runway during take off

MAP was around 26" with a Density Altitude of 5600 ft. at an elevation of 2940 ft.

Sensenich states that the Static RPM should be 2050 to 2250, and interestingly I've never seen a correction for static rpm for differing Density Altitudes.
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Last edited by az_gila : 12-02-2017 at 01:08 PM.
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  #5  
Old 11-28-2017, 04:32 PM
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snopercod snopercod is offline
 
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I did a full-power static runup today with my fixed pitch prop and got 2,300 RPM.
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  #6  
Old 12-02-2017, 11:41 AM
Tram Tram is offline
 
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Anyone have any numbers for an O-320? I' m seeing about 2200 static, but have told we should be seeing closer to 2350?
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  #7  
Old 12-02-2017, 12:40 PM
rv7charlie rv7charlie is offline
 
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Y'all need to remember that there will be significant variation in static/takeoff rpm with various brands/pitches of fixed pitch props. 'Traditional' type fp props will have higher static if they're cut for climb, and lower if cut for cruise. Flexible props like the old Bernie Warnke 'almost constant speed' fp props will show higher static while maintaining the same cruise rpm as a 'cruise' prop, assuming same MAP.

So it's not really productive to ask someone else about their numbers, unless they have exactly the same airframe, t/o weight, engine, propeller, etc, as you.

The only really useful number to me is rpm at full throttle, leaned for best power, at ~8,000 feet, along with true airspeed at those settings. (Might not apply to the Sensenich metal f/p for 160HP, since you can't run it above 2600.)

Charlie
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  #8  
Old 12-02-2017, 02:00 PM
moosepileit moosepileit is offline
 
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9:1 O-320, Vetterman crossover, mags, Carb that flows 14gph wide open in flight, 79 inch pitch 70CM6 (between cruise and climb), 2300 plus rpm once all unstalled at about 30 or so knots static std day about 800'msl.
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Last edited by moosepileit : 12-02-2017 at 03:16 PM.
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  #9  
Old Today, 03:02 PM
Turbo69bird Turbo69bird is offline
 
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0320 at 195ft summer I was seeing 2150 winter Iím seeing 2240 static
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  #10  
Old Today, 03:20 PM
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Like said, what it should be depends on choices, do you want an effective high altitude cruise prop or one giving the best take off performance... and so on.

The generic rule I tell my students: If it does not give you over 2100 during the take off roll, you should definitely suspect that something is wrong unless you have been briefed specifically about it for the AC.
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