S

smoke

Active Member
Hi all -
I recently picked up a Warnke 3 blade propeller for my RV4 to use as a spare, just in case... our runway is not in the best condition.
Can someone help me with the data numbers...
The hub says" RV4, 160 H.P
3,60,72-84".
I assume the 3 and the 60 equate to 3 blade, 60 in diameter. What is the meaning of the 72-84 ??
Thanks!
 
I would say its a 72" pitch. Have you measured the diameter? 60" is a bit small in diameter for an O320. Most of the O320 three blade RV props I make are 64-66" in dia.

Also, there were only 6 (at most) three blade Warnke props ever made to my knowledge. Two by Bernie and four by Margaret.
 
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The blade is designed to flex as it is loaded, as I recall.

I suspect the two numbers relate to the pitch of the blade at static flex, and full flex.

This is something I am pulling up out of the dark, dust, corner of my poor mind's basement-----but I think it is correct.
 
N164fj said:
Also, there were only 6 (at most) three blade Warnke props ever made to my knowledge. Two by Bernie and four by Margaret.
Click to expand...

Wow..... I feel honored! I own a 3-blade 'Air Claw' made by Margie Warnke. :) However, I'm not the original owner, so I cannot answer your question about the specs.
 
Yes, the measured diameter is 60".
The previous owner said that he had both a 3 blade and a 2 blade Warnke prop on his RV4. The 2 blade was 4 mph faster, but the 3 blade out climbed it by 400fpm. He did say that the 3 blade required much more right rudder on t.o. and climb.
 
Warnke "air claw"

O.k. all of you prop experts, riddle me this?
After installing the air claw prop, torque checks, tracking checks and run up were complied with.
1st flight had some very unusual observations...
on take off roll, the rpm was 2325. normal climb at 80kt. { pushed the nose over just a little, throttle still open. The RPM decreased to 2200. this was noticed in sound and tachometer.
Letting the aircraft accelerate to normal cruising speed, the RPM leveled out at 2400 with 155 kt being indicated.
Now, this really seems strange to me...level flight, 2300 RPM, pull the nose up and the RPM increased to 2400 - Throttle never touched.

Whats up ???
 
smoke said:
Hi all -
I recently picked up a Warnke 3 blade propeller for my RV4 to use as a spare, just in case... our runway is not in the best condition.
Can someone help me with the data numbers...
The hub says" RV4, 160 H.P
3,60,72-84".
I assume the 3 and the 60 equate to 3 blade, 60 in diameter. What is the meaning of the 72-84 ??
Thanks!
Click to expand...

72 would be the approximate pitch at takeoff and 84 would be the approximate pitch at top end, leveled out cruise after three minutes...all dependent on horse power of engine (not all engines created equal), torque that prop experiences at both these settings (takeoff and top end) and speed of aircraft.
 
smoke said:
Hi all -
I recently picked up a Warnke 3 blade propeller for my RV4 to use as a spare, just in case... our runway is not in the best condition.
Can someone help me with the data numbers...
The hub says" RV4, 160 H.P
3,60,72-84".
I assume the 3 and the 60 equate to 3 blade, 60 in diameter. What is the meaning of the 72-84 ??
Thanks!
Click to expand...

A word of caution. I suggest you be very careful if you hang that propeller on your airplane and try some high RPM runs. Bernie Warnke made a lot of props when he was in business. He came up with several different designs, but did not seem to stay with one design for long. I had a Warnke "high aspect" prop that was suppose to be magic. The tips were fiberglass wrapped, and fiberglass was working under the painted surface. Paint wrinkles developed in the painted tip area, and when you sanded them out and repainted the tip, the same wrinkles reocurred. In time that probably would lead to delamination. For that reason I quit using the Warnke that I purchased from Bernie.

Using an unproven propeller (not a Warnke) in 1989 caused me an uninsured nearly total loss of my RV-4.

I have a lot of respect for propellers. If you want a three-bladed wood prop my suggestion is to go with a Catto.
 
smoke said:
O.k. all of you prop experts, riddle me this?
After installing the air claw prop, torque checks, tracking checks and run up were complied with.
1st flight had some very unusual observations...
on take off roll, the rpm was 2325. normal climb at 80kt. { pushed the nose over just a little, throttle still open. The RPM decreased to 2200. this was noticed in sound and tachometer.
Letting the aircraft accelerate to normal cruising speed, the RPM leveled out at 2400 with 155 kt being indicated.
Now, this really seems strange to me...level flight, 2300 RPM, pull the nose up and the RPM increased to 2400 - Throttle never touched.

Whats up ???
Click to expand...

I need some more specifics. Is it a "standard" stock engine? That means nothing altered and cam-shaft has a straight line torque curve common for your engine? What is weight of your aircraft? When you pushed nose over what was your speed changing to? How long were you in level flight prior to your increase in RPM before you pulled the nose up? Lastly you noted it was an "airclaw", does it say that or does it say Warnke? any details are helpful in looking at the whole unit as a system-
 
All prop makers have had some styles that worked better than others. All prop manufacturers have had negative results. Bernie Warnke had one of the safest records out there. He made propellers for NASA at one time. I am familiar with the thin blade you are speculating. Many, if not all other brands of wood props have produced a "bubbling" effect between the wood and fiberglass or carbon fiber. All will over time. It has to do with the flexing action of the propeller. The narrow blade design had great action and was simply a shorter hour propeller. A propeller that is a high laminate fiberglass wrapped propeller is still stronger than a thick plank (5 laminates) style prop, which cannot flex under load, thus causing more of a catastrophic break when it does fail. Propellers are a moving part of airplane that are designed to be replaced and should be (just like any other part on an engine,etc) after the manufacturers maximum recommended flight time. There are wood propellers that last many years on aircraft with high flight time on them, it depends on the design, how the owner flies it and maintenance/care.
 
Jaknjoan said:
A word of caution. I suggest you be very careful if you hang that propeller on your airplane and try some high RPM runs. Bernie Warnke made a lot of props when he was in business. He came up with several different designs, but did not seem to stay with one design for long. I had a Warnke "high aspect" prop that was suppose to be magic. The tips were fiberglass wrapped, and fiberglass was working under the painted surface. Paint wrinkles developed in the painted tip area, and when you sanded them out and repainted the tip, the same wrinkles reocurred. In time that probably would lead to delamination. For that reason I quit using the Warnke that I purchased from Bernie.

Using an unproven propeller (not a Warnke) in 1989 caused me an uninsured nearly total loss of my RV-4.

I have a lot of respect for propellers. If you want a three-bladed wood prop my suggestion is to go with a Catto.
Click to expand...

You offer very wise advice to all. Run up any new propeller to different rpm settings, go full throttle if you can. This puts a high stress load on the propeller. Make sure people are clear always! Then shut down and re-check torque etc and inspect carefully before flight. For first flight always stay in pattern at first, then go high above pattern and do different tests of climb, full top end, dive (it is always a good idea to hire a test pilot who can handle the possibilities should anything arise).
 
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