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  #21  
Old 04-01-2020, 07:18 AM
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pstraub pstraub is offline
 
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Location: Hensley Airpark, TN
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Originally Posted by Stitch462 View Post
Looks sharp and love the two-tone grey paint job. Well done.
Thanks very much Stitch :-)

Quote:
Originally Posted by RFSchaller View Post
When something causes me to repitch the two blade I groan. Canít imagine the aggravation of trying to get THREE blades all singing the same song!😜
Hi Rich, I was thinking the same....I have to say it was not bad at all. I just finished setting initial pitch per the KAI (71.1 degrees +/- .1) The smaller blades are easier to work with and the new hub is really nice, clamp bolts work great and did not tend to disturb the setting when torquing. I was able to set all 3 blades to 71.1 without any trouble or drama!
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N917PB, SN 120971
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  #22  
Old 04-01-2020, 07:29 AM
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Default Question for Scott or Greg....

Hi Van's, I used the KAI recommended initial prop pitch of 71.1 degrees. Interesting that the KAI said the setting should be exactly 71.1 for a 912iS install, and for a 912ULS, 71.1 is a good starting point (not sure how to interpret that). Is there a target RPM I should look for at Sea Level, WOT (stationary or rolling). Any data for RPM expected behind a 912ULS in any phase would be appreciated. Thanks, Paul
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N917PB, SN 120971
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  #23  
Old 04-01-2020, 04:44 PM
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Location: Richland, WA
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Assuming a Rotax 912ULS the Rotax manual states the static RPM should not be less than 5200 RPM at Wide Open Throttle (WOT). Rotax Owners website says that it is desirable to achieve 5500 to 5800 RPM WOT for Takeoff and Climb.
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Bruce Rawlins
Richland, WA
RV-12 Flying
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  #24  
Old 04-01-2020, 07:09 PM
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Piper J3 Piper J3 is offline
 
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Originally Posted by printbr View Post
Rotax Owners website says that it is desirable to achieve 5500 to 5800 RPM WOT for Takeoff and Climb.
If you pitch prop for 5500 to 5800 RPM WOT for takeoff and climb you will have low cruising speed because blade pitch is too flat.

RV-12 sweet spot for prop pitch is 5150 - 5200 in initial climb at somewhere around 1000 MSL.
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Jim Stricker
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 542

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #25  
Old 04-01-2020, 07:11 PM
NinerBikes NinerBikes is online now
 
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Quote:
Originally Posted by Piper J3 View Post
If you pitch prop for 5500 to 5800 RPM WOT for takeoff and climb you will have low cruising speed because blade pitch is too flat.

RV-12 sweet spot for prop pitch is 5150 - 5200 in initial climb at somewhere around 1000 MSL.
At Vy or Vx? Rate of climb at gross 1320 # ?
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  #26  
Old 04-01-2020, 07:43 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by pstraub View Post
Hi Van's, I used the KAI recommended initial prop pitch of 71.1 degrees. Interesting that the KAI said the setting should be exactly 71.1 for a 912iS install, and for a 912ULS, 71.1 is a good starting point (not sure how to interpret that). Is there a target RPM I should look for at Sea Level, WOT (stationary or rolling). Any data for RPM expected behind a 912ULS in any phase would be appreciated. Thanks, Paul
Testing showed the speed performance of the 3 blade to be pretty much identical to the two blade, with the 3 blade providing a slight increase in climb rate.

With this being true, if you pitch for the same RPM you typically saw with the two blade in a specific cruise condition (possibly mined from your EFIS data) you will probably be happy with that setting).

As a rough suggestion, a couple tenths of a degree less pitch than 71.1 12iS value might put it pretty close depending on what you had chosen as an optimal setting for how you fly your airplane. The reason for this is that the 912iS torque curve peaks at a bit lower RPM than it does on the ULS, so a typical ULS pitch setting (for the preference of most people) will probably be a couple tenths of a degree less pitch than it would for an iS.
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  #27  
Old 04-01-2020, 08:59 PM
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Thanks Scott and all for the comments/suggestions. I finished the work on the spinner tonight, so it's ready for at least some static testing. I ended up with all 3 blades set at 71.1, I will see what that yields and adjust from there. Hoping to fly in the next day or two depending on weather here in East TN.
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N917PB, SN 120971
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  #28  
Old 04-04-2020, 05:34 AM
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Quote:
Originally Posted by rvbuilder2002 View Post
I may be off a bit (memory is going bad) but I think it is just shy of 6 lbs lighter.
Seemed hard to believe when we first weighed it but each blade is quite a bit lighter than the what a 2 blade blade is, plus the lower hub mass. It all adds up......
The new prop looks great but I canít seem to locate the weight of the new 3 blade prop, can anyone confirm? I donít think there is much weight difference and the quote above could be an initial guess.

Thanks
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  #29  
Old 04-04-2020, 06:19 AM
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Piper J3 Piper J3 is offline
 
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Does prop, as furnished by Van's, come with datum station and weight specific to RV-12 so W&B can be corrected for this installation?
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Jim Stricker
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
Bought Flying RV-12 #120058 Oct 2015 with 48TT - Hobbs now 542

LSRM-A Certificate 2016 for RV-12 N633CM
Special Thanks... EJ Trucks - USN Crew Chief A-4 Skyhawk
MJ Stricker (Father & CFI) - USAAF 1st Lt. Captain B-17H
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  #30  
Old 04-04-2020, 09:00 AM
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Quote:
Originally Posted by piperpilot View Post
The new prop looks great but I canít seem to locate the weight of the new 3 blade prop, can anyone confirm? I donít think there is much weight difference and the quote above could be an initial guess.

Thanks
The nearly 6 pounds lighter is still valid.
The actual installation weight delta is slightly less because of differences in installation hardware so call it somewhere between 4 - 5 pounds lighter.
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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