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| Propeller blade angle for Low pitch/high RPM stop https://www.warbirdinformationexchange.org/phpBB3/viewtopic.php?f=52&t=54768 |
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| Author: | Smaehr [ Sat Dec 13, 2014 8:07 am ] |
| Post subject: | Propeller blade angle for Low pitch/high RPM stop |
I am looking for feedback on what blade angle people are using for the low pitch/ high rpm stop. The military apparently used 13 degrees but 11.5 degrees is apparently also approved. Pro's and Con's? |
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| Author: | bdk [ Thu Dec 18, 2014 1:30 pm ] |
| Post subject: | Re: Propeller blade angle for Low pitch/high RPM stop |
Pitch settings at 42 in. sta.: 11.5° low, 27° high All that's allowed per the US Type Certificate Data Sheet. http://www.airweb.faa.gov/Regulatory_an ... 20R-16.pdf |
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| Author: | 51fixer [ Thu Dec 18, 2014 1:57 pm ] |
| Post subject: | Re: Propeller blade angle for Low pitch/high RPM stop |
Is it US Registered and Normal Category? Then US TCDS applies. If foreign based or experimental then ???? Was it functioning OK giving 2250 RPM? FWIW The low RPM Pitch Stop will not be reached in normal ops except pulling the prop back to low RPM on Shutdown. High Rpm is the important one to ensure you can get full Power RPM. |
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| Author: | Smaehr [ Fri Dec 19, 2014 7:28 am ] |
| Post subject: | Re: Propeller blade angle for Low pitch/high RPM stop |
Yes I am aware the 11.5 degree setting is approved. My aircraft is Normal Category and I have no complaints about the current setup. I am interested in what most people have their planes setup on and the differences in performance. For example, I can leave my prop in low rpm and start my taxi without getting the backfiring that some do with the 13 degree low stop. Curious as to the effect on takeoff and climb performance. |
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| Author: | 51fixer [ Fri Dec 19, 2014 7:11 pm ] |
| Post subject: | Re: Propeller blade angle for Low pitch/high RPM stop |
Smaehr wrote: Yes I am aware the 11.5 degree setting is approved. My aircraft is Normal Category and I have no complaints about the current setup. I am interested in what most people have their planes setup on and the differences in performance. For example, I can leave my prop in low rpm and start my taxi without getting the backfiring that some do with the 13 degree low stop. Curious as to the effect on takeoff and climb performance. Why would you keep it in low RPM to taxi? Manuals say to advance after start and you have solid oil pressure. Rings and oil scavenge like RPM. Higher engine speed moves more oil around as well. Just wondering what you feel the advantages are for doing so. Do you have Standard blower or 12-1 Blower gears? Backfiring is a mixture thing. Just retard the throttle and it should go away and advance prop for more RPM and it shouldn't bark. Only Prop setting specs are from TCDS and making 2250 RPM on the engine. Since you have a variety of blade lengths and prop profile and thicknesses from years of use and overhauls its a bit difficult to have any 2 A/C exactly the same. They often each have a personality. |
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| Author: | Smaehr [ Sun Dec 21, 2014 10:04 am ] |
| Post subject: | Re: Propeller blade angle for Low pitch/high RPM stop |
I normally put the prop in high rpm after starting. I was told that if you leave it pulled back and gave it a little throttle, it would let you know that you forgot by backfiring. |
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