Author Topic: Culver Cadet Propeller  (Read 3315 times)

ndeye

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Culver Cadet Propeller
« on: March 12, 2013, 12:00:58 PM »
I need a propeller, can anyone help me?
Using a Sensenich 70 "-56 Prop My static rpm is 2100rpm, climb out, gear retracted I am climbing 1500 fpm at 2500 rpm, level at 3000' my airspeed is 120 knots at 2500 rpm with my throttle pull back to about haft throttle. At full throttle my airspeed was 140 knots with the rpm passing Thur 2800 where I pulled it back to 2500 rpm. Can anyone recommend a 70" adjustable pitch for me and were I can buy one?

Brett Lovett

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Re: Culver Cadet Propeller
« Reply #1 on: March 12, 2013, 02:59:22 PM »
Which engine do you have?

By the way, my LCA is NC37818, s/n 329, one serial number after yours.  Wasn't yours in a museum in Fond du Lac WI a few years back?

I'll assume you have the Franklin 4AC-199E3. Based on that, the numbers you are showing seem rather odd to me.  The standard propeller for the Culver L-AR-90 (essentially a Cadet with tricycle gear and a 4AC-199E3) was a Sensenich 70AF56, so that should be the right propeller for you. You may still be interested in an adjustable pitch propeller, but I don't think the fixed pitch prop is responsible for these odd numbers (unless possibly you are using a different model than the AF).  With a 56 inch pitch (fixed) prop, I would expect approximately 2300 static RPM and approximately 2500 to 2550 RPM in level flight with full throttle (with a true airspeed of about 115 knots @ 2500 RPM), with the climb RPM somewhere in between. 

The very low static RPM and very high full throttle level flight RPM are what I find particularly odd.  Have you verified the RPM with an optical/digital tach?  Mechanical tachs are often inaccurate.  Your airspeed indicator could also be inaccurate.  I've found a few old Aeromarine airspeed indicators that read about 10% higher than they should.   Beyond that, I would investigate the engine (things such as ignition timing, throttle operation, carburetor adjustments, etc.) as a cause prior to changing props.

Unfortunately I don't know of any good solutions for an adjustable pitch propeller.  Culver originally used Freedman-Burnham ground adjustable propellers on the Cadets, but changed to fixed pitch Sensenich props sometime fairly early in production.  Here's a link to some photos of Freedman-Burnham propellers including one on a Culver:  http://www.notplanejane.com/freedman.htm.  I believe an airworthy Freedman-Burnham will be fairly difficult to come by.  They've been out of production for a long time.  I don't know of any certified adjustable pitch propellers currently in production.  Sensenich makes them for experimental & LSA. 

ndeye

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Re: Culver Cadet Propeller
« Reply #2 on: March 13, 2013, 02:36:37 PM »
Thanks for your interest, I borrowed a digital tact form our local AI and comfirm that the tact is correct. I flew 2 magnetic courses at 90 and 270 degrees and comparing my average airspeed with my GPS at 3ooo feet at 120 knots indicated and both of the averages were within a couple of knots. This is the Culver from Wisconsin the owner before then had the engine torn down for inspection do to a prop strike and at that time the high  compression pistons were installed. While in Wisconsin the engine was certified as not airworthy due to prop strikes. I disassembled and truck the airplane to South Carolina, I spent 3 years overhaul the engine, and rebuilding the airplane. Now I am looking for a certified prop new or used.

Brett Lovett

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Re: Culver Cadet Propeller
« Reply #3 on: March 13, 2013, 10:05:23 PM »
I was just throwing out ideas.  At 2500 RPM your airspeed sounds fairly close to what I'd expect, perhaps a little on the fast side, still within 5 knots.  However I find the fact that you're turning 100 RPM below static limits at full throttle on the ground and more than 300 RPM above redline at full throttle in level flight very odd.  I don't think that should be physically possible with a fixed pitch wood Sensenich 70AB56 propeller in combination with the Franklin 4AC-199E3 engine. 

I see in your aircraft paperwork file that a Sensenich 70AB56 propeller is listed as having been installed with the Franklin 4AC-199-E3 engine.  I believe I was in error above in my comments in the previous post about the 70AF56 prop.  From what I can find the 70AB for the 4AC-199 engine should have a 4 inch thick hub, but otherwise be identical to the 70AF propeller with a 3.25 inch thick hub for the 4AC-176.  This is a bit confusing as Sensenich apparently also used the AB designation for some propellers designed for a B-type hub with a No. 20 spline shaft (Continental R-670 and Ranger) which would certainly not fit on a Franklin.  I found in my notes that Culver did list the Sensenich 70AB56 (not 70AF56) propeller in their aircraft specifications for the L-AR-90.  I previously thought the AB was a typo.   
« Last Edit: March 13, 2013, 10:07:48 PM by Brett Lovett »

ndeye

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Re: Culver Cadet Propeller
« Reply #4 on: March 14, 2013, 09:18:31 AM »
Thanks for the information. Too bad the FAA won't let me use any of the newer carbon fiber props without changing the registration to experimental. I will be a volunteer at Sun & Fun again this year and maybe I might find a beech Robby prop.

Unwichtig54

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Re: Culver Cadet Propeller
« Reply #5 on: October 30, 2015, 05:09:35 PM »
Hi ndeye,
did you already choose a propeller for your culver and are you satisfied with it? I have quite the same problem as you’ve described above. When going faster than 120MPH I over speed the propeller, so I have to throttle back to about half the power.
I have a 75HP Continental engine installed.