B

bill price

Member
I am running a Great American wood prop on a 1984 RV-4. I got new a thunderstorm last summer and into a little rain. I throttled back a couple hundred RPM's but still got some errosion on the leading edge. I wnat to go to a metal prop. My prop is a 68 X 70. I get 150 kts TAS at 9000' and climb is around 1700 ft/min with the wife. I can hit TPA by the end of the runway by myself (145 lbs) and although it is great I would prefer more speed and range and be able to go into rain. I have the 160 hp 320. My range at 2700 RPM is only 3 hours with a 1 hour reserve. I fly across Nevada and Eastern Oregon and it can be 1 hour between airports with fuel so I have to be careful. Vans has a 70 X 77 prop which I hope would give me more speed but I am after range more than anything.

any experience out there?

Bill
 
To be honest I wouldn't expect any more speed or surely no more climb with the RPM restricted metal prop. I'm thinking of going to a Catto with edge protection so I can have the best of both worlds. I climb at 2250 RPM @ 1200 f/min and cruise around 155 kts at 7000' (2500 RPM) with this over pitched prop (79). The metal prop is durable but it sure limits the performance of the -4.
 
Sid Lambert said:
To be honest I wouldn't expect any more speed or surely no more climb with the RPM restricted metal prop. I'm thinking of going to a Catto with edge protection so I can have the best of both worlds. I climb at 2250 RPM @ 1200 f/min and cruise around 155 kts at 7000' (2500 RPM) with this over pitched prop (79). The metal prop is durable but it sure limits the performance of the -4.
Click to expand...

The RPM restriction does not affect climb. You will not be turning 2600 rpm on climb. The 150/160 Sensenich is a very good prop. What you loose with the 2600 rpm limit, you make up for in efficiency.
On the other hand, I couldn't give up my Catto either.
 
I went to the Catto site and their claim is that it holds up reasonably well in rain. I'm an MEI CFII and need to be able to go IFR if need be. It gives me so many more options for distance flying. Have you run your Catto in rain?

Bill
 
Catto in Rain

I have a -4 and have used 3 props. Since I live in Northern Idaho we get lots of rain. The first prop was wood, an Aymar-Demuth. It was a good prop until I lost part of one blade one day. I refinished it a couple of times. You could repair your prop by useing something like JB weld or epoxy and microballoons to fill the pits, then sand to the prop contour. Paint and then good as new. I always ran 2100 rpm in the rain, and it wouldn't chew it up too bad.

The second prop was a 2 blade Catto. It did fine, same drill. Throttle back to 2100 RPM and go. It is still in service on an RV-6, and I saw it Saturday at the NW RV fly in. It is based on the field there in the Portland area, and you know they get a lot of rain. It had some very minor pits out near the tips. I think it is doing great.

My current prop is a 3 blade Catto. Since it has a smaller diameter you can run it at a higher rpm without damage. I fly IFR so I spend some time in the clouds, and got some significant ice on one flight this winter. When that happens you don't have the luxury of slowing down. On that flight I got quite a bit of erosion on one of the tips. I called Craig Catto and asked him how to repair it. He said to use JB weld to fill in the holes. I did that and then decided to have him paint it for me since he does it every day. I also had him put leading edge tape on it. It came back looking great with the tape on. He told me I didn't even need to throttle back if I don't want to now.

As far as performance goes, the 2 blade catto and the wood Aymar demuth were hard to tell apart for top speed. I have an O-360, and a 975 lb airplane and I was getting as much as 190 knots TAS (calibrated, speed runs in multiple directions) with them. The 3 blade with tape is a couple of knots slower. On Saturday on the way home from Scapoose I did a full throttle run just to see what things looked like with the tape and it ran 184 knots TAS at 7500 msl and 182 knots at 9500 msl. I haven't calibrated things lately, but it looks like you give up a little bit of efficiency when you put the tape on.
 
Mel said:
The RPM restriction does not affect climb. You will not be turning 2600 rpm on climb. The 150/160 Sensenich is a very good prop. What you loose with the 2600 rpm limit, you make up for in efficiency.
On the other hand, I couldn't give up my Catto either.
Click to expand...

Yes, the RPM restriction doesn't come in to play during climb but the aggressive pitch to keep the prop under 2600 in cruise limits the RPM and available power during the climb. I have new plastics (SJ wheel pants and intersection fairings) on the airplane now so I need to do a new round of testing when the weather breaks.
 
Brent.

What are the diameters and pitches of your props. I bought some tape from an outfit back East and have not put it on yet. I am on vacation at the moment so I don't have the name of the brand. I was at 9000' and still could go over redline by 150 RPM. I need some taller gears.

Bill Price
N32KX.
 
bill price said:
Brent.

What are the diameters and pitches of your props. I bought some tape from an outfit back East and have not put it on yet. I am on vacation at the moment so I don't have the name of the brand. I was at 9000' and still could go over redline by 150 RPM. I need some taller gears.

Bill Price
N32KX.
Click to expand...

I don't have the diameters and pitches handy, but I will try to remember to get them. My engine also goes to about 2850 (and sometimes higher) when running all out. I am OK with this for the following reasons: It means that the prop will give a better climb rate because it will run at a higher RPM/manifold pressure during the climb. Secondly, I almost never run wide open in cruise to save gas. I use a cruise RPM of 2500 or so and 18 in MP. This gives me a 165 knot TAS cruise speed when heavy and around 170 knot at the end of the flight, and 8 GPH. I usually plan at 160 knots for IFR and always beat the time.

But when you want to go fast, that extra RPM available means more HP. The Catto prop is rated for 3300 RPM, I believe. The engine is supposed to reach TBO running 100% of the time at redline of 2700, and they run them without damage at Reno at very high RPM. The only time I really run over 2700 is when I want to go fast for some reason, like seeing whose plane is faster. I have not tried to race another O-360 powered -4, but I have walked away from a -6, -7, -8, and -10. I'm sure some of the speed freaks out there are faster, but so far I haven't found them.

I told Craig when I bought the last prop that I wanted the wide open throttle to be 2850 RPM, and he pretty much nailed it. I wouldn't worry about running there once in a while. I doubt it has any significant effect on engine life, and it sure doesn't hurt the prop (at least a wood or composite one).

I may be wrong, but I believe the 2700 RPM limitation has more to do with metal prop testing limitations and the vibration interactions between the prop and the engine. Also on dynamic counterweighted engines I would be reluctant to go past redline. My 2 cents. YMMV.
 
Prop me up...

I beta-tested Craig's first 2 blade RV prop on my -4 in 1999. It was the best prop I had tried at the time and outperformed my Sterba hands down. A friend loaned me his Sensy metal for the 150/160 Lycoming and frankly I didn't like it. It was heavy, had harmonics and I liked being able to get rated RPM flat out if I wanted to. It also is not recommended for aerobatics, a deal breaker for me.
Rain erosion was always a factor living in the SE USA on all my props. I tried the leading edge tape on my Catto and it worked with a 1-2% performance penalty. Eventually I went to a 175HP 0-320 wide deck and a 2 blade fixed pitch MT prop. The MT was "the goo" with all the same performance, no rain restrictions and smooth, very smooth. Cost about the same as the Sensy with no RPM restrictions, much lighter, acro-capable, factory built and looks cool!

My dos centavos...

Smokey
HR2
 
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MT prop

My MT is installed and flight tested. Faster than the Warnke by maybe 7 mph. (although I'm still writing down numbers) Engine idles better, although I can't figure out why. The prop is lighter than my Warnke, so might need a landoll ring for CG purposes. (or maybe go back to the heavy Gill battery)
All in all, I LOVE the prop.... Good call Smokey. ;-)

DM
PS
My Warnke is faster above 10,000ft. Must be that long thin blade that twists. Just keeps pulling up high... Would be perfect for an RV-9

Dmadd said:
about the same as a three blade Catto. My MT should be here any day now...
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Results

Dennis,
I also purchased a new MT f/p but am not in the air yet. Getting real close!! After you put a few hours on it I'd really like to hear your impressions and results if you get time to post.

Thanks,
 
Brian,
This prop rocks. Does everything better than before. Even DECELERATES the A/C better. Wide chord blade windmills to slow you down. My other prop wouldn't do that. Acceleration better, climb better, friends say the plane is slightly quieter during a flyover. Thats interesting because I have Vetterman four pipe exhaust, which make the engine sound "built". The best part is I can fly in the rain.
Your gonna love it.
Dennis.

Brian Vickers said:
Dennis,
I also purchased a new MT f/p but am not in the air yet. Getting real close!! After you put a few hours on it I'd really like to hear your impressions and results if you get time to post.

Thanks,
Click to expand...
 
Others note when the tape is used to protect the Catto prop, it will have a slight performance decrease. On the MT Prop site, it says they use a stainless steel erosion sheath on the leading edge. I suppose this is different than the tape that Catto uses? Do all MT props come with this sheath? I'm curious if others think this sheath also would show a slight performance decrease because of it.
 
No degradation

There's no degradation from the sheath as it is flush with the rest of the blade. On a new prop you can't tell its there as its painted over. A few flights through rain showers will pulverize the paint off the leading edges revealing the stainless steel. The root of the blades have a black PU covering that seems very tough. Picture below is of my current project that is being rebuilt, with fixed pitch MT.

Pete

Prop.jpg
 
MT FIXED PITCH PROP

Dennis
I presently have a 3 bladded Catto on my -4 but I'm interested in the MT.
Did you purchased your prop in the States or directly from the factory in Germany and how long did you have to wait for it.Craig Catto has a waiting time of more than 6 months and I don't wanna be grounded too long if I sell my Catto too quickly?
Did MT custom built your prop to your specifications or are they one size fit all type?
Thank you for your time

Bruno
[email protected]
 
Bruno,
got it here.
http://www.flight-resource.com
It took about a month. I just told them RV-4 with an O-320 d2j, and they took it from there. I did get the choice of climb, cruise or in between (which I took) Went flying yesterday even though it was raining... because I could. <BG> Love the prop.
good luck,
Dennis
Ps
tell Jon at Flight resource I said hello. Nice guy.


RV-4 said:
Dennis
I presently have a 3 bladded Catto on my -4 but I'm interested in the MT.
Did you purchased your prop in the States or directly from the factory in Germany and how long did you have to wait for it.Craig Catto has a waiting time of more than 6 months and I don't wanna be grounded too long if I sell my Catto too quickly?
Did MT custom built your prop to your specifications or are they one size fit all type?
Thank you for your time

Bruno
[email protected]
Click to expand...
 
MT PROP

Thanks for the info Dennis,I just send a request for a quote on a 3 Bladded fixed pitch prop..
We,ll see how it goes
Cheers

Bruno
 
1st MT prop on an RV4

Here was the first MT 2 blade FP on an RV4, El Bandito Bueno! It beta-tested so well, the German engineer's data was within 1% of his calculations! Of all nine props I tried over fifteen years including the first Catto, this one had all the "right moves". Rain erosion was a non-issue, no performance degradation and looks cool!

Highly recommended!

Smokey
HR2

 
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catto prop

I put my Catto prop on this weekend. I had an old Great American 68/70 prop and my Catto is a 70/72. I went from 141 knots cruise to 163 @ 10,000 pressure altitude. I was turning 2700 rpm on both test flights. I still had a little throttle left but with the Great American prop I had 150 rpm lift at 10k. I had it painted silver and Craig put red and orange trim strips on the tips and it looks terrific. I seem to have the same climb I had always had, 75 kts and 1700 fpm with my 160 hp 0-320.

Very smooth.

Bill.
 
Sensenich Prop Question

Hi I have purchased an RV-4 project which has a Lyc 160 and a new Sensenich RV Prop with 79 pitch, which I believe to be incorrect for this HP. Does anyone have any experience with this HP/pitch combination? I am contemplating selling the prop in order to finance a Catto or similar composite prop with the correct pitch, thanks.

Scott
 
ScottHess said:
Hi I have purchased an RV-4 project which has a Lyc 160 and a new Sensenich RV Prop with 79 pitch, which I believe to be incorrect for this HP. Does anyone have any experience with this HP/pitch combination? I am contemplating selling the prop in order to finance a Catto or similar composite prop with the correct pitch, thanks.

Scott
Click to expand...

That's <arguably> a climb prop for an RV-4 in that it has 2" less pitch than recommended for the 160 hp engine. It will work fine for you or you could spend a few dollars and have it re-pitched. Either way, it'll probably be less expensive than selling it at a loss and then buying another prop.

What you really need to ask yourself is which compromise you prefer - a metal prop that is essentially maintenance free, but is heavy and has RPM limitations, or a wood prop, which is light, but will require maintenance and will force you to modify your operating procedures when flying through rain.
 
MT prop

Smokey, Demo just sent that MT prop back to get reworked and I don't think it had many hours on it. The cost was $1000.00. It's a great running prop but it's recent overhaul made me wonder about long term durability. Of course, nothing's perfect.
 
We have a 79" Sensi on our RV-4 and like it a lot. It is a climb prop but also up at 11.5K, we can still get 2600 rpm out of it so it makes a great cruising prop at high altitudes.
 
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