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Author Topic: maximum rpm's for apc props  (Read 987 times)

Offline kenneth cook

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maximum rpm's for apc props
« on: May 11, 2008, 06:15:19 PM »
         I recently came across a 6.3x4 APC propellor which I put on a Norvel.15 AME BB. The instructions state the use of a APC 7x4. We tached the engine at 24k plus with the 6.3 x4 prop. We flew the plane and I was observing that the prop had a crazy looking fracture running perpindicular to the blade. This appears to me as if the prop was trying to throw a blade. The prop didn't contact anything on startup or landing. There is some white crazing on both the front and back of the blade. Is it possible that I was crossing the line of when things decide to depart? This engine has been surprisingly working out very well for us. I'm just a bit curious if anyone ever experienced anything like that. Its also a bit of a wake up call to stay on your toes to avoid incidents. Ken
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Offline ray copeland

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Re: maximum rpm's for apc props
« Reply #1 on: May 12, 2008, 06:54:10 PM »
Hey Kenneth!  I don't know anything about the questions you asked, but i have a Norvel .15 AME looking for a plane and i love the way it starts and runs on the bench. My question is what plane are you flying ?  Thanks, Ray
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Ray from Greensboro, North Carolina , six laps inverted so far with my hand held vertically!!! (forgot to mention, none level!) AMA# 902150

Offline Roger Vizioli

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Re: maximum rpm's for apc props
« Reply #2 on: May 13, 2008, 06:16:07 AM »
Quote from: ray copeland on May 12, 2008, 06:54:10 PM
Hey Kenneth!  I don't know anything about the questions you asked, but i have a Norvel .15 AME looking for a plane and i love the way it starts and runs on the bench. My question is what plane are you flying ?  Thanks, Ray
[/color]

Ray,
FYI
I have a CL Norvel .15 CL version that will go in a Ringmaster 307, 38" span/307 sq. in. from Pat Johnston.
Plan is to start building in a few weeks.
Roger V.
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Roger Vizioli
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Offline Leonard Rennick

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Re: maximum rpm's for apc props
« Reply #3 on: May 13, 2008, 12:04:34 PM »
Ray,

If you want to have a lot of fun, get an F2D plane and but the Norvel on it. Put a 7x4 APC or 7x4 wood zinger and 60 ft lines. As long as you fly over grass you will have hard time hurting the plane. I've seen them go straight in and bury the engine with no damage to the plane.

Leonard
« Last Edit: May 14, 2008, 09:09:59 AM by Leonard Rennick »
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Leonard Rennick AMA 865846

Offline Scott Jenkins

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Re: maximum rpm's for apc props
« Reply #4 on: May 13, 2008, 04:19:17 PM »
Ken,
Here is the fromula off the APC Prop web site "Maximum RPM=190,000/prop diameter (inches)" 190,000/6.3= 30158 rpm. That is a honking Norvel you got there, by chance did you check the prop before putting it on that motor  ::) if you see any crazing in the plastic "THROW IT AWAY" props do not look good sticking out of your body.
Scott
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Scott Jenkins
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FAI F2C VOLUME 2 SECTION 4, 4.3.7
m) During the refuelling and the restart of the motor, and until the time when he releases the model aircraft, the mechanic must keep the model aircraft in contact with the ground by at least one point and with the centre line outside the flight circle. During that time the pilot must be crouching or sitting inside the centre circle. He keeps one hand on the ground and his handle and his lines as close to the ground as defined by the F2C panel of judges until the model aircraft starts again.

Offline kenneth cook

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Re: maximum rpm's for apc props
« Reply #5 on: May 13, 2008, 04:36:09 PM »
         Ray, I'm using the Norvel on a foam combat wing. I don't have the exact specs on the squares of this particular wing.The wingspan is 40.5 inches and the center is 11'' from leading edge to trailing. The engine is running with bladder. I'm pretty sure its from Corehouse. Originally the plane was owned by a club member of ours using a Big Mig .15. I couldn't use the stock needle  it came with. Phil C. told me to purchase a OS1a needle from Towers which screwed directly into the venturi. I just filed it down a bit so its projection into the ventui was same as the stock unit. I get very good runs using this needle. This was a nice install I just rotated the needle to point back towards the cylinder. Were flying with 50' lines and its a blast.  Ken
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Offline phil c

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Re: maximum rpm's for apc props
« Reply #6 on: May 14, 2008, 10:11:44 AM »
APC props will fatigue if they are overstressed.  If you look closely at the blades there will be whitish areas about 1/3-1/2 the way to the tip.  I've never had one actually fail in flight, but I check them afterwards and bend the prop.  If it is fatigued it will just break, where a new one won't.

I've used the 8/5 Sport prop on the Nelson 36 for quite some time. They never broke, although after 10-12 flights I'd usually throw them away anyway.
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phil Cartier

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