Wood prop

Who knows the dif in weight between Alum and wood props? If engine stoppage which would cause more drag? Larry you were talking about wings made me thing About 2000 there was a guy trying to get a new wing design going for Coupes wonder what ever became of that.

Well not being an Engineer. I cannot believe ERCO would want to loose anything using a small engine like C85. Wood props were less used by general aviation... Pitch and RPM has more to do with pulling than how long the prop is. And there is an efficiency dif between wood and Alum props also thin vs a club.

I have seen some arguments that upgrading the engine C-75 to C-85 doesn't gain you much if you have to change to a shorter propeller. The C-75 allows a larger diameter propeller (73, I think), so going to a C-85 may give more HP, but a smaller propeller (71 inch) with less lift area doesn't give much additional thrust. A wood propeller can be as large as 74" diameter.

This all assuming I am reading the Type Cert correctly.

larger jets require a larger venti + more fuel more air. Just basic stuff Contact Vern see if he has an C85 carb. Mac, I am going to look see if I have a good 71 with a 51 pitch. I know I have 48 and 49  there is no change in weigh...

The carb change assumes a Stromberg. I’m not sure you can make the coupe light enough to make a noticeable difference in its glide. The fat wing pretty much precludes “soaring”. My best glide is 80. Basically, you just have to get used to that green circle around your plane in ForeFlight being real close…

Thank you Larry, very helpful. So if I understand you correctly 75 to 85 is essentially a carb change so weight change N/A but more power and a requirement to change the prop ($3,500 - $5,500) - ish and while wood lightens the overall empty weight it also changes the weight and balance a good bit. What I'd like to do is to lighten as much as possible in order to improve glide rate if at all possible without messing with the W&B. I probably am spoiled by the 150's 70mph glide when doing "power out" and with Tweety it is more like 80 mph to maintain the same 700 fpm descent.