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Re: Whirlwind Propeller blades

Posted: 26 Nov 2017 00:31
by SHIPCHIEF
The plywood pitch fixture fits over the front of the downward sweeping blade. You slide it in from the tip until it snugs over the leading and trailing edges. It will need to be set vertical. It will rock and needs to be stabilized. Holding it in place with the digital level is quite a hand full.
I used this little furniture clamp to hold the digital level to the fixture. The clamp was placed so the back jaw rested on the propeller blade like a 3 leg stool, so the digital level's base was parallel to the propeller blade.
Then I used a carpenter's level to make sure the fixture was vertical.
Also the blade must be horizontal, and this needs to be done several times. I stood a ladder next to the blade tip and marked a reference point.
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Re: Whirlwind Propeller blades

Posted: 17 Mar 2018 22:11
by SHIPCHIEF
Today I put the DynaVibe prop balancer on the Yak, the first time with the new blades.
I flew the Yak yesterday, and the vibrations were pretty bad, similar to the original paddle prop, feeling like a washing machine on spin cycle with all my blue jeans on one side.. Although the tip vortex vibration around the canopy is much less.
This time I left the cowling in place. I could actually fly this while taking DynaVibe readings.
RPM had to stay fairly low because the brakes couldn't hold beyond about 1200 prop RPM. 2.86IPS @ 1009 RPM is pretty bad.
I slacked-off the counterweight clamp and unthreaded the light (#1) blade 1 turn for a slight improvement. Then I added some vinyl 'speed tape' to the light blade. now the DynaVibe indicated the heavy spot was not in line with a blade. I have no spinner, so weight goes on the hub. I find some metric screws and some washers, and don't like the look of these washers bedding over a ridge on the blade retaining ring, so I look at the other side of the hub to see what the Russians do....and realize I've been staring at 2 'half moon' weights held in by 3 screws...on the heavy side!
Off comes the safety wire, three screws and two 'Half Moon' weights. Also the 'speed tape' from #1 blade.
The next reading was a fairly respectable .26 IPS @ 1032 RPM, abut 90% better! All the trouble with prop balance for the previous owner and me has been the excess weight on one side of the #2 blade retainer, which moves the heavy point out of line with the prop blades.
The Yak is back in the hangar tonight. The #1 blade will be turned back in and the pitch set with the electronic level to match the #2 blade. I'll try again tomorrow and I now have a couple of weights and hardware on hand to get it right.
Had I known about the weights, instead of seeing them but not comprehending what they are....I would have taken them off before the first flight with the W-530 blades.

Re: Whirlwind Propeller blades

Posted: 19 Mar 2018 13:45
by SHIPCHIEF
Yesterday I spent most of the day with the Yak & Dyna Vibe.
I eventually ended up frustrated. The frame I made to hold the synchronizing light and the vibration transducer may be vibrating from propeller beat airflow or something...
I tried several combinations of weights and locations, and chained the tail to my tractor as depicted on my vibration post. Then I ran the engine up to high cruise RPM. I couldn't get any readings less than .30 IPS with any stability in value or degrees, especially as I changed RPM.
Dyna Vibe manual, Pg-18 trouble shooting addresses this. I'll need to make a shorter, more rigid mount.
So Flight Testing was done with no balance weights, a big improvement, noticeable upon engine start-up, and 90% better during all flight, but not perfect.
Now the original V-530 Russian prop blades (refinished by Whirlwind) can be compared to Whirlwinds special W-530 blades, and the difference is profound.
The thrust is greater, the ground run shorter, the climb is steeper and speed recovery after an aerobatic maneuver is a bit faster. level speed might be 10 KPM (6MPH) faster as well, but I also added wheel pants sooo....no real surprise.
W-530 blades just sound and feel better. They are a bit sharp on the hands when pulling thru the prop blades before starting. :!: