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  #11  
Old 09-20-2021, 08:04 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
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Quote:
Originally Posted by EricTheRV8er View Post
Very interesting on the RPM limit. Everything I read mentions the 2600rpm limit.

As to the pitch, I have not been able to verify what it's pitched at, just going on a piece of paper I found with that line highlighted...would need to take to prop shop to verify.

I am seeing around 2200 static, which I understand is on the high end (fine pitch) of the suggested envelope.
I believe the O-360 doesn’t have that 2600 rpm restriction, only the O320. What are you reading that says otherwise?

Also your oil temp on the pic of the G3X looks like you could warm it up a little.. perhaps some aluminum foil tape? I prefer 185 to 200 to cook off the moisture.
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Last edited by Taltruda : 09-20-2021 at 08:09 PM.
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  #12  
Old 09-20-2021, 08:19 PM
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EricTheRV8er EricTheRV8er is offline
 
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Location: Smithfield North Carolina
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Quote:
Originally Posted by Taltruda View Post
I believe the O-360 doesn’t have that 2600 rpm restriction, only the O320. What are you reading that says otherwise?

Also your oil temp on the pic of the G3X looks like you could warm it up a little.. perhaps some aluminum foil tape? I prefer 185 to 200 to cook off the moisture.

I'm going off what Sensenich has on their Application Guide...https://www.sensenich.com/wp-content...1349891787.pdf

The last page shows "Placard required to avoid operation above 2600 RPM. Unless I missed something in the literature, it doesn't specify engine type. Seems to be a universal limitation.
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  #13  
Old 09-20-2021, 08:22 PM
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EricTheRV8er EricTheRV8er is offline
 
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Quote:
Originally Posted by Taltruda View Post
I believe the O-360 doesn’t have that 2600 rpm restriction, only the O320. What are you reading that says otherwise?

Also your oil temp on the pic of the G3X looks like you could warm it up a little.. perhaps some aluminum foil tape? I prefer 185 to 200 to cook off the moisture.
Duh... just saw the last column and #8 does not apply to our engine!

You are correct. Thank you for making me look this over more carefully!
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  #14  
Old 09-20-2021, 08:49 PM
blaplante blaplante is offline
 
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Default Why 2600 rpm on the o-320?

Now I'm curious. Anyone know why the 2600 rpm redline on the o-320 engines? [And the o-360 180 hp]. Seems like the smaller displacement o-320 is going to make smaller thrust pulses on the prop than an o-360 200 HP. Resonant frequency issue?
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  #15  
Old 09-20-2021, 09:11 PM
Taltruda Taltruda is offline
 
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Quote:
Originally Posted by EricTheRV8er View Post
Duh... just saw the last column and #8 does not apply to our engine!

You are correct. Thank you for making me look this over more carefully!
Nice.. now go fly tomorrow and let her rip! My -4 with the O360 and the same prop you have does 171 knots true at 12,500 18 inches, 2660 RPM 9.5 G/HR. I do have to throttle back a little so she won’t overspeed. WOT is 18.5 inches, and it’ll go over 2700, so I throttle back to an even 18 inches then lean for max rpm.
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Last edited by Taltruda : 09-20-2021 at 09:15 PM.
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  #16  
Old 09-20-2021, 11:17 PM
gasman gasman is offline
 
Join Date: Mar 2007
Location: Sonoma County
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From Van's......

70CM (150/160 HP) PROPELLERS ARE LIMITED TO MAXIMUM 2600 RPM..... This is not your prop.

Here's how to decode the part numbers: PROP 70CM7S9-0 (81) means: 70 = design diameter in inches, CM = designator for O-320, 7 = bolt diameter in 16ths of an inch, S = requires crank spacer, 9 = length of spacer in 1/4s of an inch, 0=full length blade (not cut down) (81) = pitch in inches.

The Sensenich metal propellers for the O-360 that have part numbers starting with PROP 72FM8S(xx-x) are NOT CERTIFIED.

https://shop.vansaircraft.com/cgi-bin/shop.cgi
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  #17  
Old 09-21-2021, 06:13 AM
calpilot calpilot is offline
 
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fly an equilateral triangle (heading 360; 120; and 240) at the same indicated airspeed. Write down the "true airspeed" and "ground speed" numbers. Divide by 3, they should equal. If not, look for static leaks. I was able to bring my speeds into calibration using a small (.040) dam in front of the static ports.

DAR Gary
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  #18  
Old 09-21-2021, 08:22 AM
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EricTheRV8er EricTheRV8er is offline
 
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Flew a quick test flight this morning and was seeing ~160kts TAS at 7500' and 70% HP.

These are just figures off the G3X. Need to do some calibration tests and the TAS triangle. I will also do some at 11,500' and see. Will do that this weekend when the weather improves.



Thanks for the info everyone.

https://vansairforce.net/community/a...1&d=1632233781
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  #19  
Old 09-21-2021, 11:08 AM
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Carl Froehlich Carl Froehlich is offline
 
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Quote:
Originally Posted by EricTheRV8er View Post
Flew a quick test flight this morning and was seeing ~160kts TAS at 7500' and 70% HP. SNIP
Yep - slower than your plane could be, but consistent with my experience flying my first RV-8A with that FP prop. I did 300 hours flying behind that prop before I replaced it with the nice Hartzell BA prop. It became a new plane. I tell builders using this FP prop was my big mistake on that build, but I was following the advice of those who went before me.

The new RV-8 (180hp IO-360) has the same Hartzell prop and typical LOP cruise is 170kts (heavy) to 175 knots (solo). Fuel burn in between 8.5gph and 7.5gph (8K - 12K’).

I note that any propeller’s ability to transform engine power to thrust is a far more complicated equation than just pitch. I flew and RV-14 with a fancy custom composite two blade CS prop that was ~5kts slower in cruise than expected. It took all the 390 power just fine, I suspect however some was wasted on just thrashing the air.

Carl
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  #20  
Old 09-21-2021, 11:17 AM
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EricTheRV8er EricTheRV8er is offline
 
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Quote:
Originally Posted by Carl Froehlich View Post
Yep - slower than your plane could be, but consistent with my experience flying my first RV-8A with that FP prop. I did 300 hours flying behind that prop before I replaced it with the nice Hartzell BA prop. It became a new plane. I tell builders using this FP prop was my big mistake on that build, but I was following the advice of those who went before me.

The new RV-8 (180hp IO-360) has the same Hartzell prop and typical LOP cruise is 170kts (heavy) to 175 knots (solo). Fuel burn in between 8.5gph and 7.5gph (8K - 12K’).

Carl
Thanks for the info.

So you converted your -8A from fixed pitch to C/S? I know this engine has a hollow crank, so it could be done. Is there much involved besides the obvious? Did it require a new cowl or a cowl modification? And what speed bump did you see after converting?
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