After going through builder's withdrawl, I've decided to do a partial build and give the aluminum mistress a nose job.
I'm converting the standard Vans cowl to the Sam James cowl and plenum.
With 480 hours on the current plane I have a good baseline. When perfectly leaned to best performance, I get 168-170 knots TAS at cruise which is normally between 9,000 and 12,000 feet, WOT, 90 degrees ROP, 2,400 RPM, on an IO360 (180hp) and MT CS prop.
I've been told that approximately 37% of the drag on our planes is due to cooling. With that being said, I will be interesting to see what changes I get in performance by making this conversion. If I don't pick up any speed, I will be mildly disappointed but not completely since I get to fix a few things that bother me about the current cowl......and I also think they look cool.
Performance gains are expected from:
1 - Intake change from snorkle to snout. Current air intake is in the left inlet and will be going to the lower cowl. This is supposed to give me 1 more inch of ram pressure at cruise.
2 - Cooling drag reduction.
My anticipated increase in performance is somewhere around 10 knots. I'll post again once it is finsihed and let everyone know if it was worth it.
I'm converting the standard Vans cowl to the Sam James cowl and plenum.
With 480 hours on the current plane I have a good baseline. When perfectly leaned to best performance, I get 168-170 knots TAS at cruise which is normally between 9,000 and 12,000 feet, WOT, 90 degrees ROP, 2,400 RPM, on an IO360 (180hp) and MT CS prop.
I've been told that approximately 37% of the drag on our planes is due to cooling. With that being said, I will be interesting to see what changes I get in performance by making this conversion. If I don't pick up any speed, I will be mildly disappointed but not completely since I get to fix a few things that bother me about the current cowl......and I also think they look cool.
Performance gains are expected from:
1 - Intake change from snorkle to snout. Current air intake is in the left inlet and will be going to the lower cowl. This is supposed to give me 1 more inch of ram pressure at cruise.
2 - Cooling drag reduction.
My anticipated increase in performance is somewhere around 10 knots. I'll post again once it is finsihed and let everyone know if it was worth it.
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