2005 Catto 3 Blade vs 2014 Catto 3

[db1yg]

Latest Catto Design


I recently had the opportunity to test some of Craig Catto?s latest designs on my 2006 RV9a/180. Since I had been talking to him about my need for more pitch and the fact that I had some prop testing experience with him, he shipped me two prototypes (a 68x76 and a 68x75) of his latest (March 2014) three bladed carbon fiber over laminate for testing head to head with my 2005 vintage fiberglass over laminate three blade. This new design is probably close to that recently tested by Axel on his RV4/160. After Axel?s tests, I understand that Craig mounted it on his personal RV6/160 and refined the design further, then made the modifications necessary to match it to a 180 hp RV. The following is some of the data that I provided Craig after around 8 hrs flying behind these two propellers.

BTW, I apologize for the formatting issues on the raw data. I had the data spread nicely under the column heads but my word processing system does not play nicely with VAF's software--however, I think you will follow!

2005 Catto 3 Blade vs. 2014 Catto 3 Blade Design

The following comparison testing on the latest Catto design carbon fiber over wood 3 blade vs. the older design fiber glass over wood 3 blade was done from KPRC (Prescott, AZ) from a field elevation of 5050 ft. All power data was recorded by an Advanced Flight Systems AF-2500 Electronic Engine Management System while all flight data was taken from a Dynon D10a Electronic Flight Information System. The true airspeed and density altitude data is from the Dynon which has been certified for IFR flight and the static system has been calibrated and verified accurate to within 1 kt below 160 kts and 1.5 kts above 160 kts. The posted data has been corrected for the measured static system error. All data was based on 3 runs averaged. If a run was significantly different or encountered other than smooth air, it was discarded and an additional flight was conducted.

The aircraft on which the props were tested is a Van?s RV9a equipped with an Eci I0360/180hp (stock compression) engine fired by a Lightspeed Plasma III electronic ignition on one side and a stock Slick magneto on the other. The FI system is from Air Flow Performance. The aircraft has a Sam James cowl/plenum --otherwise the airframe is stock with the exception of some detail aerodynamic clean up.



2005 Catto 2014 Catto 2014 Catto
(66x76) (68x75) (68x76)
I. Prior to Take-off

F/P Run up Rich (rpm) 2200 2200 2160
F/P Run up Leaned 2240 2245 2210

II. Take Off

RPM at Lift Off 2210 2190 2165
Speed at Lift Off (kts) 75 75 75


III. Climb Out 110 kts from 7 to 8000 Density Alt

RPM (ave) 2425 2295 2285
Climb Rate (FPM) 1400 1300 1150



IV. Cruise at 9k Density Altitude

MP/GPH----RPM/KTAS by Prop

2005 (66x76) 2014 (68x75) 2014 (68x76)


19/8.4 2540/159 2450/159.5 2383/158

20/9.0 2600/163.5 2520/165 2457/163

21/9.9 2660/167.5 2590/170 2530/168.5

22/10.5 2730/173.5 2660/176.5 2600/174





V. Wide Open Throttle Run 9K Density

I addition to the above cruise tests, I did WOT runs on both propellers. The wot speed at 9k density went up by 2+ kts while the rpm went down when compared to the 2005 prop.



Notes/Comments:

1. Cruise power was set by leaning to peak power/rpm with the 2005 prop and then using the same fuel flow and mp setting on the 2014 prop tests. The objective was to produce equal or higher speed on lower rpm with the same mp and ff--which both the 68x76 and the 68x75 accomplished.
2. Cruise data was captured at 9k density altitude in smooth air with the auto pilot/altitude hold engaged. Rough air data was discarded.
3. Multiple runs were made at all settings for both props, statistically inconsistent data discarded, and the 3 most consistent runs on each prop were averaged.
4. All tests were initiated with full fuel and solo which results in the cg being forward of the range mid point.
5. The 2005 fiberglass over laminate Catto 3 blade (66x76) weighed in at 17 lbs while the 2014 carbon fiber over laminate Catto 3 blade propellers both weighed in at 12.4 lbs.
6. The new design is noticeably thinner than the old throughout the blade length--especially at the blade root. The aft side of the blade root is somewhat concave. The hub is 3.75 inches thick while the hub on the 2005 unit is 4.25 inches thick.
7. Both props were incredibly smooth across the entire rpm range.
8. The 68x75 was flown from Prescott (ele 5050 ft) to Lake Havasu City (ele 870 ft) where take off and climb performance picked up significantly when compared to the high altitude take off and climb data from Prescott. However, how can you complain about 1300 fpm from 7 to 8k ft at 110 kts--we RV drivers are a spoiled lot!!
9. I may also be testing a 68x74 of the same design--if so I will post the comparatives.


Conclusion: This design exceeded my hopes----equal speed at low power cruise, better speed at mid to high power cruise, and all at a lower rpm. The 76? was clearly too much pitch for my stock 180hp James equipped 9a--I will be going with either a 74? or a 75?. Craig tells me that this design will be available with the nickel leading edge.

I also have some pics of the new design mounted on 9db if anyone has any interest.


Cheers,

db

[Zuldarin]

DB that is great news! Thanks so much for posting this information. The 68x74 carbon composite three blade is exactly the prop I just purchased from Craig (with Nickel LE). Now if I could just get it in the air! :-)

[AX-O]

Nice job with the write up.

[RVbySDI]

DB,
Top notch write up and testing procedures!

I have been flying with a 2009 68x72 3-blade since completion on my 180 hp 9A since it first flew in July 2010. After quite a few speed test flights it became obvious that I did not have the correct pitch setup for my 9A. I finally received a new prop from Craig with the new thinner blade design. It is a 68x74 3-blade with the Nickel leading edge. I have not been able to fly it yet but am hopeful I will get in the air soon with it. Your write up was just what I was hoping to see for comparison purposes when I am able to do my testing.

[sbalmos]

Excellent write-up. Continues to validate my decision to eventually buy a 3-blade, maybe while I'm talking with Craig at Oshkosh again this year. Works of art from both a visual and efficiency engineering perspective.

Has anyone ever done a similar comparison between his 2 blade vs 3 blade? Last year Craig said the differences performance-wise are basically insignificant. I'm just curious what the differences really are (aside from the 3 blade looking far too cool to pass up. ).

[db1yg]

Hi Scott,

If we do not have anyone who has the comparitive data on the two blade vs three blade now---I have a buddy here in Prescott who just ordered the new design two blade and he also has a 9a/180. I will post up when he and I can fly together!!

Also, thanks to all for the nice comments on the testing procedures!

Cheers,

db

[Buggsy2]

I just picked up last week a 3-blade prop for an RV-9A (I'm about 60 miles from his airport shop). Catto had, 6 months prior, cut my spinner and match-drilled the backplates and spinner for the older style prop...and now they didn't fit the new, thinner prop! But Good Guy Craig Catto swapped all my old for new, including a different thickness Sabre crush plate.

It's really a work of art, and I can hardly wait to try it out...but that will be at least a year

As to this data, I noticed that the 2005 prop gets you more than 20% better climb rate (1150fpm 2014 68x75 vs. 1400fpm 2005 66x76), while only losing 0.5 to 1.0 kts at identical MP and fuel flow. So why wouldn't the older or smaller pitched prop be considered superior?

[db1yg]

The following pics show the blade shape of the newer Catto. In the first pic the new blade is on top with my 2005 fiberglass on the bottom. The second pic gives you some idea of how the blade root is shaped. Note that the hub on the newer design is 3.75 inches vs 4.25 inches on my older prop.

[db1yg]

Hi Ralph,

I just saw your comments/questions regarding the propeller tests in post #7--sorry for the late response--been out of town.

You asked why the 2005 was not superior to the new design due to the climb rate of 1400 fpm vs 1150 fpm. First, the 1150 fpm was with the new design 76" pitch prop, not the 75", which was clearly too much pitch for my RV9a/180. The climb rate for the 75" pitch new design was only off by 100 fpm. The big advantage, in my opinion, was that both the new design 75" and 76" were faster in "mid power and up" cruise at the same ff and mp but at a significantly lower rpm--which suggests more speed on less horsepower--for which I will trade off a small decrease in climb any day! The fact that I also lost 4 lbs off the nose of my "A" model RV9 was also a plus.

I would also speculate that, based on my test data from the 75" and the 76", the new design in 74" pitch would post equal or better climb performance than the 2005 prop AND STILL cruise faster at lower rpm. I hope to determine this by testing the newer 68x74--if so I will update the data.

Cheers,

db

[flightlogic]

Great report! You are gonna cost me money eventually. I can just sense it in my peripheral vision.