C201 337 approval for Franklin

[crbnunit]

Putting an 82" on the IO-360 was a pretty noticeable performance increase. This is just seat of the pants and I have no numbers to back it up but I am taking off from some pretty short strips with a lot more buffer room than I used to have and I can climb above obstacles from these strips with more clearance as well. So take that for what it is worth. It pulls harder and it it climbs better. As said above, where you will see an immediate difference is when you drop to idle on final. It is like throwing an anchor out there. This a switch from a 76" to a "long" 82 though. I wouldn't go back.

[stick_rudder]

FARMAULE,

Not that there isn’t a performance gain with the C201 on wheels, just that I could easily tell a large performance gain on floats and have a harder time quantifying the gain on wheels, though I know there must be an increase in performance on wheels. It was much easier to see the performance gain on floats. Which the C22 on floats, there was a ‘dead zone’ after liftoff from the water where the aircraft would neither climb or accelerate. With the C201, that dead zone went away and the aircraft now both climbs and accelerates continually after breaking free from the water. I really wish I had access to a scale setup that measured effective thrust. Would be fun to have some actual numbers of thrust differences.

That’s my opinion on the larger prop anyways. I use all the performance gain I can get out of it and wouldn’t go back to a C22, but I push my plane hard, not everyone does or needs to.

[Andy Young]

Not sure why, butt float planes often seem to be much more responsive to prop improvements that land planes. Maybe it has to do with overcoming much, much more initial drag? Thinking about it that way, you’re in the static or near-static thrust regime for much longer when trying to get going in the water, whereas a land plane gets moving much quicker, and therefore gets into the moving thrust regime earlier. Maybe that’s all hogwash; who knows.

[TxAgfisher]

Go for it!

[1:1 Scale]

Fwiw, I got to borrow an 82" prop (forget the model, but not a C201) while my 78" C201 was getting resealed. The loaner prop didn't have the fine pitch stops set for the Franklin, so I wasn't getting full rpm at the beginning of the takeoff roll, but there was a noticeable improvement in thrust as soon as the throttle was cracked open.

I would imagine there's a measurable difference in takeoff roll when the full rpm is available.