Has anyone strapped the Hartzell N7605W-2X composite blades onto an RV-4 that has a Sam James cowling?
I have sifted through several threads of great experiences with these blades on RV-7’s and -8’s, some with Vans cowlings and some with Sam James cowlings (“short” and “long”) using either the “G” hub (1.00” longer than the “C” hub) on Vans cowlings or the “M” hub (+2.563” longer than the “C” hub) on SJ cowlings. My -4 came with a late 1990’s SJ cowling, HC-C2YR hub with F7666A-2 blades bolted to a Lyc O-360. I understand most SJ cowlings using the “C” hub also have prop spacers of around 2.5”. Mine does not, however the cowling seems to be fitted as far aft as possible which makes the cooling inlets a bit shorter than what might be optimal.
I fly formation and light aerobatics from a high desert airport which can have DA’s over 10K in the summer. From what I have been reading the Hartzell (or WW) prop should perform much better than the F7666A blades.
The cord of the N7605W blades is almost 2x that of the F7666A blades. From a conversation with Hartzell when using the G2YR hub the trailing edge of the blade at station 12” is 2.32” forward of the crankshaft flange when at low pitch and 1.16” at high pitch (34 deg). My SJ cowling front surface is 1.25” forward of the crankshaft flange so by my math (1.16 – 1.25 = -.11”) the trailing edge of the prop at full pitch will hit the cowling. Hartzell suggested using their “I” hub which is 1.0” longer than the “G” hub (which is 1” longer than the “C” hub I have now).
Questions:
Does anyone else have a Hartzell HC-G2YR hub on a -4 with SJ cowling?
If so, what is the distance from the crankshaft flange to the front of your cowling?
Has anyone run a 74” prop on an RV-4? Vans recommends 72” max on their taildraggers, 74” on the -A models. I currently have a 72” but it doesn’t seem like a 74” would be a problem, even with wheel landings.
If I go with the “I” hub I believe I will end up with a 2.00” gap from the back of the spinner to the front of the cowling. Hartzell said there is some (up to ½”) adjustment via washers but at best that is still 1.5” of gap.
What have others done to close the gap?
Any RV-4’s with SJ cowling + composite prop setups out their? I also looked into the WW-74HRT but that hub is really short and would require at least a 2.5” extension.
Thanks!
I have sifted through several threads of great experiences with these blades on RV-7’s and -8’s, some with Vans cowlings and some with Sam James cowlings (“short” and “long”) using either the “G” hub (1.00” longer than the “C” hub) on Vans cowlings or the “M” hub (+2.563” longer than the “C” hub) on SJ cowlings. My -4 came with a late 1990’s SJ cowling, HC-C2YR hub with F7666A-2 blades bolted to a Lyc O-360. I understand most SJ cowlings using the “C” hub also have prop spacers of around 2.5”. Mine does not, however the cowling seems to be fitted as far aft as possible which makes the cooling inlets a bit shorter than what might be optimal.
I fly formation and light aerobatics from a high desert airport which can have DA’s over 10K in the summer. From what I have been reading the Hartzell (or WW) prop should perform much better than the F7666A blades.
The cord of the N7605W blades is almost 2x that of the F7666A blades. From a conversation with Hartzell when using the G2YR hub the trailing edge of the blade at station 12” is 2.32” forward of the crankshaft flange when at low pitch and 1.16” at high pitch (34 deg). My SJ cowling front surface is 1.25” forward of the crankshaft flange so by my math (1.16 – 1.25 = -.11”) the trailing edge of the prop at full pitch will hit the cowling. Hartzell suggested using their “I” hub which is 1.0” longer than the “G” hub (which is 1” longer than the “C” hub I have now).
Questions:
Does anyone else have a Hartzell HC-G2YR hub on a -4 with SJ cowling?
If so, what is the distance from the crankshaft flange to the front of your cowling?
Has anyone run a 74” prop on an RV-4? Vans recommends 72” max on their taildraggers, 74” on the -A models. I currently have a 72” but it doesn’t seem like a 74” would be a problem, even with wheel landings.
If I go with the “I” hub I believe I will end up with a 2.00” gap from the back of the spinner to the front of the cowling. Hartzell said there is some (up to ½”) adjustment via washers but at best that is still 1.5” of gap.
What have others done to close the gap?
Any RV-4’s with SJ cowling + composite prop setups out their? I also looked into the WW-74HRT but that hub is really short and would require at least a 2.5” extension.
Thanks!
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