New CarbonCub Prop

[Rick Bosshardt]

Hi Randy/Pete;
I know you guys are at Oshkosh (wish I could be there!), so you can get back to the Forum on your return, but I was wondering if you had any performance specs, or better yet improvement performance numbers, with the new CarbonCub prop versus the 78" prop I have on my January 2013 vintage CarbonCub?

It sure looks nice with the nickel leading edge, which wont peel off like the plastic protector on our leading edge.. .and I know its 80"..... sure makes me WANT to get the new one, purely for looks, but its hard to accept the price tag, considering that I dont have much chance of selling my 'old' one with 60 hours on it.... I have tried but no interest. I also see David selling a new one on the On Line store, from your inventory of 78" props, and its not moved at $1200.

So.... I was wondering how much better performing it really is? The best reference will be from someone such as yourselves who can fly both versions right after each other and really feel and see if there is a difference.

And... any 'upgrade' promotions from CubCrafter, Randy?

Thx, Rick

[Bob Watkins]

Rick...I just bought and installed the new nickel leading edge, 50" pitch, 80" prop on my Carbon Cub S/N 150.

The new prop is 7 to 8 MPH faster than the original 55" pitch - 78" long prop. But the original prop is a better climber. ORIGINAL PROP - Take off 25 gal. + pilot, sea level, 80F, flaps up: = 1,500 FPM minimum, at 2,500RPM, at 90MPH. The new prop however needs closer to 100MPH to get 2,500 RPM for the same climb rate in the same summer weather.

Haven't confirmed new prop GPH for leaned, then enriched for best power. Will be doing that on an upcoming trip. Old Prop averaged 6.5GPH at 2,400 RPM, 7,000 to 8,000 ft. ALT. My guess is the added speed is coming from the longer more efficient prop, (but hopefully not more GPH). Could be a mix of both.

Total prop efficiency usually is not much greater than 70%. Shorter props and added blades are less efficient. Changing length can increase or decrease efficiency as high as to the 5th power...within the practical mean prop size for any given horsepower. Here is what I got on the new Prop:

CRUISE CONFIGURATION: FULL COWL FLAPS OPEN, ORIGINAL COWL but w/larger heater mod scoop, and new starter mod....2,400 RPM, 8.0 TIRES. Engine well broken in, high compression, 300 hours TT.

BARO ALT. DENSITY ALT. TAS- MPH KNOTS
11500 12500 115 100
10500 11500 117 102
9500 10500 117 102
8500 9300 120 104
7500 8170 122 106

Bob Watkins
Lear 36
MU-2
Carbon Cub

[Rick Bosshardt]

Rick...I just bought and installed the new nickel leading edge, 50" pitch, 80" prop on my Carbon Cub S/N 150.

The new prop is 7 to 8 MPH faster than the original 55" pitch - 78" long prop. But the original prop is a better climber. ORIGINAL PROP - Take off 25 gal. + pilot, sea level, 80F, flaps up: = 1,500 FPM minimum, at 2,500RPM, at 90MPH. The new prop however needs closer to 100MPH to get 2,500 RPM for the same climb rate in the same summer weather.

Haven't confirmed new prop GPH for leaned, then enriched for best power. Will be doing that on an upcoming trip. Old Prop averaged 6.5GPH at 2,400 RPM, 7,000 to 8,000 ft. ALT. My guess is the added speed is coming from the longer more efficient prop, (but hopefully not more GPH). Could be a mix of both.

Total prop efficiency usually is not much greater than 70%. Shorter props and added blades are less efficient. Changing length can increase or decrease efficiency as high as to the 5th power...within the practical mean prop size for any given horsepower. Here is what I got on the new Prop:

CRUISE CONFIGURATION: FULL COWL FLAPS OPEN, ORIGINAL COWL but w/larger heater mod scoop, and new starter mod....2,400 RPM, 8.0 TIRES. Engine well broken in, high compression, 300 hours TT.

BARO ALT. DENSITY ALT. TAS- MPH KNOTS
11500 12500 115 100
10500 11500 117 102
9500 10500 117 102
8500 9300 120 104
7500 8170 122 106

Bob Watkins
Lear 36
MU-2
Carbon Cub

THANKS Bob! Great analysis you have done so far! It helps allot.
Given my mission is more low and slow and landing at shorter strips.... I guess I might end having the better prop for that. Id rather have the climb performance than the extra few knots of cruise speed....
Did you just tuck your old prop away in your hangar, or did you find a home for it?
Thx, Rick

[Bob Watkins]

Rick - I am keeping my prop for sure in case I want to go climbing!!

Actually it has been a problem landing on grass fields. The plastic leading edge cover keeps cracking and breaking every 180 hours or so... which leads to balance issues when we replace the leading edge...causing us to re-balance. We like the nickel leading edge a lot and the prop is absolutely glass smooth right out of the box. It is the smoothest the Cub has ever been. I'm not keen on going to the Sensenich Prop factory to balance 20 miles away. THEY MIGHT MESS IT UP!!! - Bob Watkins

[randylervold]

Rick, our test data is very similar to Bob's results. In summary the new 80" will provide...

• Same top speed wide open (I don't think Bob tested at 2700 rpm)
• Better speed at cruise rpms by 4-5 mph (we didn't get the increase Bob did but then we tested at lower altitudes)
• Slightly worse climb rate
• Better durability with the nickel leading edge
• 1.4 lbs lighter!

Bob's points about replacing the urethane LE tape occasionally and that effects balance are good ones worth considering. Whether to upgrade or not depends which of the above are priorities for you.

One other thing perhaps worth mentioning is that there are new ASTM regulations going into effect around December 1st that have much more stringent prop standards. The 80" prop has been through a vibration survey where the 78" version has not. With the first version of the 80" prop a resonance was discovered at 2600 rpm. The layup schedule was changed, the test re-run, and now we KNOW we don't have any sort of potentially destructive resonance to contend with. There are some other new flight tests we'll run between now and December to show durability as well.

[Rick Bosshardt]

Rick, our test data is very similar to Bob's results. In summary the new 80" will provide...

• Same top speed wide open (I don't think Bob tested at 2700 rpm)
• Better speed at cruise rpms by 4-5 mph (we didn't get the increase Bob did but then we tested at lower altitudes)
• Slightly worse climb rate
• Better durability with the nickel leading edge
• 1.4 lbs lighter!

Bob's points about replacing the urethane LE tape occasionally and that effects balance are good ones worth considering. Whether to upgrade or not depends which of the above are priorities for you.

One other thing perhaps worth mentioning is that there are new ASTM regulations going into effect around December 1st that have much more stringent prop standards. The 80" prop has been through a vibration survey where the 78" version has not. With the first version of the 80" prop a resonance was discovered at 2600 rpm. The layup schedule was changed, the test re-run, and now we KNOW we don't have any sort of potentially destructive resonance to contend with. There are some other new flight tests we'll run between now and December to show durability as well.

Thx for getting back to me, Randy.
As you said, in the end each of us considering a switch will have to decide what our priorities are... versus the cost. Having the differences to weigh helps allot. Thanks.

Hope Oshkosh was good for CubCrafters!

Rick

[turbopilot]

Rick, our test data is very similar to Bob's results. In summary the new 80" will provide...

• Same top speed wide open (I don't think Bob tested at 2700 rpm)
• Better speed at cruise rpms by 4-5 mph (we didn't get the increase Bob did but then we tested at lower altitudes)
• Slightly worse climb rate
• Better durability with the nickel leading edge
• 1.4 lbs lighter!

Randy, don't see the prop in the store. What's the price?

[DavidB.]

http://store.cubcrafters.com/Catto-P...ip_p_1092.html

There are now pictures and a better description of this prop in the store.
If anyone has had any positive experiences with this prop compared to the old 78", I would love to here it in the form of a review in our web store.
In fact...We will pick our favorite review at the end of next week and send someone a hat. doesn't just need to be for this prop either, any review, on anything you have bought from us gets you the opportunity to get a hat next Friday

[Dan L]

Here's a link to a previous thread on the same prop
http://www.cubcraftersforums.com/sho...752-Borer-Prop

My short answer is I've been flying with the 80x50 for a while now and am very pleased with it. Better on the low end and in cruise.

[txcub]

So on new Carbon Cubs, is the Catto 80" 50 pitch with nickel leading edge the standard prop installed?

http://store.cubcrafters.com/Catto-P...ip_p_1092.html

There are now pictures and a better description of this prop in the store.
If anyone has had any positive experiences with this prop compared to the old 78", I would love to here it in the form of a review in our web store.
In fact...We will pick our favorite review at the end of next week and send someone a hat. doesn't just need to be for this prop either, any review, on anything you have bought from us gets you the opportunity to get a hat next Friday