Flybuddy2

Flybuddy2

Well Known Member
Has anyone flown the same plane with both props??
I've got my Catto prop currently with Craig Catto getting a refurb done. Overall they are good props and IMO they get better performance, are smoother running and a bunch lighter. Conversely, the Sensenich is a bolt on and forget prop, no worries about heavy rain or retorquing. I've dabbled with putting the Catto up for trade on the classified section when it comes back but I'm undecided. I'm fairly new to the RV group, what's the consensus?? thx Tom
 
No comment on the comparison but please make sure you check with your FSDO when doing the prop change. Our FSDO requires a five hour test period for such a change.
 
N941WR said:
No comment on the comparison but please make sure you check with your FSDO when doing the prop change. Our FSDO requires a five hour test period for such a change.
Click to expand...

It's all about the oplims for the plane. Older oplims do not have the major change notification requirement while newer ones do.
 
Having just done a very similar switch on my RV-4 I can give you my data:

I did lose a bit of speed, but its an apples/oranges comparison. I had a combo pitched Sensenich and the Catto is a climb pitch.

The climb performance is astonishingly different. It feels like a new plane. Cruise was 2600RPM limit on the Sensenich vs I can easily overrun the 2700 RPM on the Catto. Speed difference is maybe 3-5MPH. The lighter prop is faster to spin up and respond, it feels much more sporty.

I bought the Catto (2 blade) used. I sent it back to Craig to get refinished and repitched 50RPM lower - he nailed it.

After flying the Catto just once, I immediately sold the Sensenich. The Catto is SO smooth. In my case, doing some aerobatics, puttering around and not really doing much cross country, the tradeoff is very easy. If you are doing a lot of cross country travel, then maybe the Sensenich is more efficient/faster - but the dang thing was always so rough, even after dynamic balancing I just always hated it.

Anyway, thats my experience!
Steve Harris
N144SH
2001 RV-4
 
have had both

I had the Sensenich 70cm81 inch pitch on my RV-4 160hp 0-320 for about the first 350 hours and I was very pleased with the prop. I switched to the Catto prop so I could turn more than 2600 rpm. My Sens prop ran very smooth. The Catto prop is not any smoother in my opinon. A wood prop feels different than a metal prop that is true. The power pulses feel different but I would not call it smoothness. My Catto is a 68dia 65 in pitch which I sent back because it was underpitched. Craig reworked it and the only difference I could tell was that he increased the cord out farther from the hub.

The Sensi was 5 kts faster at 2600rpm than the Catto in the same conditions.

The Catto has an 11lb crush plate on it to retain the cg. 11lbs located 4inches fwd of the crank flange.

My max speed for racing is faster with the catto prop but for everyday flying I wish I had the Sensi back on it. IF it did not have that rpm limit it would be hands down the best prop out there.

Chris Murphy RACE34 RV-4
 
Performance comparisons?

Bear in mind that it is much more difficult to compare the performance of fixed pitch props than it is with constant speeds, at least as to speed. With the CS you can just set the same power (RPM-MP-DA) and compare. With fixed pitch this may well not be possible.

This is a factor that contributed to a Van's factory prop comparison, a number of years ago, where some fixed pitches (Sensenich) were faster than the CSs. The fixed pitch was pitched so that it turned over 2700 RPM, thus more power and more speed.

My prop (Sensenich 72FM8-83) is pretty fast wide open but I can rarely run wide open throttle in level flight without exceeding 2700 RPM. When I can run wide-open up above 13,000 feet or so it is quite fast. That being said, I don't know if the Catto is faster or slower.
 
I am trying to decide between the two props as well.

Here's my deal, I have a tailwheel, ADAHRS mounted near the aft deck, light on avionics. My concern is that the Catto, will result in an AFT CG. The Sensenich being heavier, will probably be better in my application.

Does that make sense?
 
W/B

apkp777 said:
I am trying to decide between the two props as well.

Here's my deal, I have a tailwheel, ADAHRS mounted near the aft deck, light on avionics. My concern is that the Catto, will result in an AFT CG. The Sensenich being heavier, will probably be better in my application.

Does that make sense?
Click to expand...

If you check it out you may find that with the spacer and heavy crush plate the whole assy with the catto prop is about the same as the metal prop.

CM
 
apkp777 said:
I am trying to decide between the two props as well.

Here's my deal, I have a tailwheel, ADAHRS mounted near the aft deck, light on avionics. My concern is that the Catto, will result in an AFT CG. The Sensenich being heavier, will probably be better in my application.

Does that make sense?
Click to expand...

Tony, better to build light and add the weight where you need than end up with a heavy plane and have to remove weight.
 
apkp777 said:
I am trying to decide between the two props as well.

Here's my deal, I have a tailwheel, ADAHRS mounted near the aft deck, light on avionics. My concern is that the Catto, will result in an AFT CG. The Sensenich being heavier, will probably be better in my application.

Does that make sense?
Click to expand...

It does make sense, but you can probably save yourself a few bucks by going wood prop and Prestolite starter. There are plenty of those starters around for nearly free, and they add ~10 pounds way up front.

So if you want a wood prop, there are ways of doing that without breaking the bank or ending up with an aft CG condition.
 
not always true in comparing CS either as MP/RPM/DA provides you the Shaft Horsepower from the engine. What makes the plane go is Thrust Horsepower which is shaft power * the prop efficiency. Prop efficiency is a very tricky variable in its own right and is effected by RPM/Dia/airfoil and DA. So simply setting engine power will not provide a valid comparison between props since you can set the same horsepower in a variety of MP/RPM combinations all of which result in different prop efficiencies.

to compare you need to know the efficiency curve for the prop you are flying and map the maximum to engine RPM for a given DA. Use this RPM to map to to the MP that provides maximum SHP. This will be the engine SHP for a given DA at which the propellor is most efficient. The prop that allows the highest SHP at maximum efficiency would be the prop with the most top end performance.

it is not an easy task to TEST prop efficiency as installed since to do so requires many data points that are easily affected by many variables. To do so thoroughly you'll need to know how to normalize the data you collect to isolate vairables such as change in weight (due to fuel burn), DA, etc..

However you can get a quick check by picking a mid power Hp for your engine.. say 150Hp and using your engine charts to find at least 4 different MP/RPM combinations that equal 150Hp (don't worry about the silly rule of never having your MP higher than your RPM - if the combination is on the chart it is a safe to operate the engine there) then go out and fly those 4 combinations while recording IAS for each. The more quickly you work through these the better your data since your weight is decreasing. Plot the data on a chart of IAS vs RPM to find the max prop efficiency RPM at 150Hp. Repeat this process for other power settings above and below 150 and plot on same chart. Now draw a line through the peaks of all those curves and this will give you an idea of how your prop efficiency changes with power and where your prop is most efficient for the flight regime you normally fly. Then you can make up a Mp/RPM chart that you bring into the cockpit so that rather than follow the overly simplistic method of flying 25/25 for cruise you may discover that flying 26"/2450 is more efficient giving you more speed for same fuel flow (which is really the measure of efficiency you are after). The closer you conduct your test with the plane in same configuration (CG,GW, etc) and test day conditions (DA) the more accurate you'll be...
 
A tool for evaluating Prop Efficiency

Most of the quote below is either completely accurate or close. However, there is an easier and more accurate way. Go to:
http://home.cogeco.ca/~n17hh/Models/models.html .
First, take a look at the prop efficiency table for the C-152. For reasons best explained elsewhere, this is the airplane about which we know the most and thus it can be used to validate our models or calculations. For an RV, the efficiencies will be closer to 80% or even better.

Use any of the models there to build your own. It will give you the most accurate numbers you can get without CAFE level instrumentation. There are new methods in there that make it both easier and more accurate than the usual approaches. Write to me if you need more help with it.

RV8R999 said:
not always true in comparing CS either as MP/RPM/DA provides you the Shaft Horsepower from the engine. What makes the plane go is Thrust Horsepower which is shaft power * the prop efficiency. Prop efficiency is a very tricky variable in its own right and is effected by RPM/Dia/airfoil and DA. So simply setting engine power will not provide a valid comparison between props since you can set the same horsepower in a variety of MP/RPM combinations all of which result in different prop efficiencies.

to compare you need to know the efficiency curve for the prop you are flying and map the maximum to engine RPM for a given DA. Use this RPM to map to to the MP that provides maximum SHP. This will be the engine SHP for a given DA at which the propellor is most efficient. The prop that allows the highest SHP at maximum efficiency would be the prop with the most top end performance.

it is not an easy task to TEST prop efficiency as installed since to do so requires many data points that are easily affected by many variables. To do so thoroughly you'll need to know how to normalize the data you collect to isolate vairables such as change in weight (due to fuel burn), DA, etc..

However you can get a quick check by picking a mid power Hp for your engine.. say 150Hp and using your engine charts to find at least 4 different MP/RPM combinations that equal 150Hp (don't worry about the silly rule of never having your MP higher than your RPM - if the combination is on the chart it is a safe to operate the engine there) then go out and fly those 4 combinations while recording IAS for each. The more quickly you work through these the better your data since your weight is decreasing. Plot the data on a chart of IAS vs RPM to find the max prop efficiency RPM at 150Hp. Repeat this process for other power settings above and below 150 and plot on same chart. Now draw a line through the peaks of all those curves and this will give you an idea of how your prop efficiency changes with power and where your prop is most efficient for the flight regime you normally fly. Then you can make up a Mp/RPM chart that you bring into the cockpit so that rather than follow the overly simplistic method of flying 25/25 for cruise you may discover that flying 26"/2450 is more efficient giving you more speed for same fuel flow (which is really the measure of efficiency you are after). The closer you conduct your test with the plane in same configuration (CG,GW, etc) and test day conditions (DA) the more accurate you'll be...
Click to expand...
 
Sport Aviation had an article on Props this month. Completely useless in making a decision! Seems that it comes down to mostly preference and cost.

I really would like a CS, just can't afford it right now. So then the descion is what is the biggest bang for the buck?

Here's the price differences I am looking at. Prices include Saber Ext ($405), Crush plate ($69) and Bolts ($75) Spacers ($22) (approx price)

Sterba Wood Prop $1200
Sensenich Wood Prop $1600
Sensenich Aluminum $$2200 (I don't think it requires an extension, $2600 if it does)
Catto $2250

So????
 
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apkp777 said:
Sterba Wood Prop $1200
Sensenich Wood Prop $1600
Sensenich Aluminum $$2200 (I don't think it requires an extension, $2600 if it does)
Catto $2250
Click to expand...
The Sensenich DOES require an extension but it is included in the price of the prop.
 
for the price

Mel said:
The Sensenich DOES require an extension but it is included in the price of the prop.
Click to expand...

for me it would be a no- brainer... metal prop. I have had both and for all around general performance you wont beat the Sensenich.


you get the weight where you want it, its maint free, any good prop shop can repitch or work on it for you......flies in the rain without worries, certified....no brainer considering the cost of the others.

CM wish had mine back now.
 
I leaning toward the Sensenich metal. I have the spinner for it already. The biggest negative though is the smooth operation of the wood/composite props. I think a well balanced metal can be pretty smooth also.
 
Tony,

Did you take a look at the Whirlwind Ground Adjustable Prop? It has a metal leading edge so no issues with flying in the rain. It weighs 18 lbs and best of all, you can tune it to your -9. List price is around $2500.

Also, the Catto two blade prop only costs $1650.
 
Bill- the prices I listed included the extension and bolts. Should be right around $2200 for the Catto.

Where did you get your Whirlwind. Their site doesn't give much info and it appears you have to buy through a dealer. Their sites don't offer much either.
 
sensi #1

i like the 85' pitch sensi with great factory support. mine has 2,700 hrs on it some in the rain ifr. i will probably get it reconditioned soon and be good for another 10 years. easy to remove for fan belt issues too. great cruize #s. enjoy. turbo;)
 
Price.

I did this a couple months ago. Wasn't buying everything from scratch, just replacing the wood prop on my RV6a o360 that had come apart.

wood Sterba was $615
wood Sensenich $1270
Whirlwind. ? called several times, left info with two different people, could never get a call back?

Also priced the composite overlayed props from Prince and Catto. .but all had too long of lead times for me.

I went with Ed Sterba who immediately started building me a prop and had one shipped to me a week later for $650 with shipping.

Very nice guy and got me back in the air quickly.
 
Looks like Van's jacked the price of the Sensenich metal props by $500. The economy must be all healed! The Sterba looks better all the time.


Sterba Wood Prop $1200
Sensenich Wood Prop $1600
Sensenich Aluminum $2700
Catto $2250

(Price includes, prop, spacer, extension and bolts)
 
MT for O-320 RV-4 was $2250. Might be a little more now that the dollar is almost worthless...
Looks great, and my plane is faster now... honest. I also don't have to get home before the rain hits anymore...

DM
 
2 Blade Catto for RV-4 / 160hp ?

If you are running a Catto in this configuration can you please tell me the dia/pitch you are using, and results? Thanks!
 
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