McCauley 7140 vs. 7440

[Douten]

Can't really remember but seems like about 2375 with both, but was reading my cub club newsletter and they were talking about having a 65 intake spider on instead of the 75-0-200 and low and behold I had the 65. since then have changed intake, carburetors, and done a few more mods and it really woke up a smart airplane. Love the 7440 so much I haven't even tried the 7144 for a couple of years now but feel like I could use more prop now. turning 2475 -2500 on climb out and have to throttle back to about 1/2 in level flight. getting off in about 150'-170' when light. we'll see if I can finally beat the T-crafts in Greenville this fall. pretty hard when you give them a 40-50 pound pilot advantage and they are some great seaplane pilots.

[gcgilpin]

Douten, are you using a Sensenich 7440 or is it a McCauley?

[Douten]

It's a McCauley, I have a local seaplane with a sensenich on a 95 hp super cub but have not tried his prop yet and don't know that pitch. I tried a sensenich 7443 against my 7144 and it was about 2-3 seconds longer off the water when on floats. also measured my McCauley against a older one and the prop width in different places were not the same. don't understand why.

[JimC]

About a year ago, in a post about 7535 performance, throughout most of the post I typoed '7545' instead of '7535'. Saying

"No, I'm not saying that I would prefer to run the 7535. There are five classes of overspeed (Categories Ia, Ib, IIa, IIb, and III). Running an O-200, you can easily reach a IIb overspeed with the 7545 (I was careful not to exceed IIa, which has the same inspection requirements as Ib). You can probably reach IIb with a C90 as well. A IIb overspeed would require that you replace the rod bolts and nuts, among a number of other unpleasant and potentially more expensive consequences. I've run a 7441, liked it, think a 7440 would do better than the 41, and that a 39 might be better still (I'm not in a hurry to get anywhere in a cub). Any flatter, and you run a severe risk of hurting the engine. I run a 7142 on a daily basis and think that on an O-200 (and probably a 90) it is a great compromise prop that won't lead a prudent pilot to hurt the engine. Being careless with the 7545 could lead to the need for an overhaul or worse within a very short period of time. That said, the 7545 performance is quite impressive, including a 55 mph climb at full rated rpm (2750 rpm) on a 95 degree day -- the 7545 just comes with a potentially exorbitant penalty".

Needless to say, I meant to say, "7535" instead of "7545". Nobody commented, so I figure all of you knew what I meant, but I thought I'd take this opportunity to correct it anyway.

BTW, my 7441 has been repitched to 7440, and I'm looking forward to comparing it against my 7142, but FedEx has been bouncing the package back and forth between Portland and Everett for two weeks now (was supposed to have come to a small town near Memphis). FedEx says it is being mis-scanned (15 scans so far between Portland and Everett), but they also say they can't do anything to stop the bouncing or redirect it toward Memphis.
Oops & Arrgh,
JimC

[JimC]

Douten, I'm curious about the 95hp SuperCub. Did you do it by STC or 337 ? Though Continental allowed the C90 to develop 95 hp during takeoff, Piper prohibited it; limiting the maximum power to 90.
JimC

[Steve Pierce]

Piper called it a PA18-95.

[JimC]

Interesting.
The PA-18 Type Certificate (T.C.D.S) 1A2 limits the engine to a maximum of 90 hp, so it isn't allowed to produce 95hp without a 337 or STC.

Reference, T.C.D.S. 1A2, Page 2, Line 1
Engine Limits For all operations, 2475 r.p.m. (90 hp.)

The use of the term PA-18-95 must have been a marketing ploy, since the type certificate didn't allow the engine to actually develop that horsepower under any circumstance.
JimC

[Steve Pierce]

I know what the TCDS says but I refer to them as PA18-95s as did Piper, so do others.

[JimC]

P.S. Much the same is true for the J3 and PA-11,

where for the J3, T.C.D.S. A-691 Item 311. C. (10) limits the power of the C-90 to 90 hp on takeoff and 80 hp for all other operations.

And for the PA-11, T.C.D.S. A-691 Item 311. D. (5) limits the power of the C-90 to 90 hp on all operations
JimC

[JimC]

P.S. Much the same is true for the J3 and PA-11,

where for the J3, T.C.D.S. A-691 Item 311. C. (10) limits the power of the C-90 to 90 hp on takeoff and 80 hp for all other operations.

And for the PA-11, T.C.D.S. A-691 Item 311. D. (5) limits the power of the C-90 to 90 hp on all operations
JimC
P.P.S. Airplanes is strange creatures, and their paperwork is even stranger.

[Douten]

maybe you misunderstood my comment I don't own the pa18-95, I have a pa-11, I noticed the other day that I turn 2475 on a steep climb then I throttle back to about 1/2 in level flight cruise about 85 indicated.