Catto 3 blades & Lyc O-360 180HP Performance

[lucaperazzolli]

Hi,

ready for first flight I saw 2100 rpm on my Van's Tach with full throttle on the runway run ....... 3 seconds - then I was waching out ;o)

Could anybody tell me something about his/her propeller performance @ take-off roll ? Just to have an idea what to expect.

My Catto numers are :

66" Diameter x 76" Pitch
0-360 180HP@2700RPM
Top Speed at Target RPM : 215mph@2800rpm
4.375" Finished Propeller Thickness

[hevansrv7a]

With a Catto 3-blade and similar static, my takeoff roll is around 700' or less, depending on weight and headwind. My best climb is around 110 knots and the RPM for that is around 2200, more or less. My top speed at 8500' and 2650 RPM is about 175 kts/ 201 mph. Your prop may not be the same as mine. Craig had to re-pitch mine; it was able to over-rev (>2700) at 8500' in the first try. The RV-8 is typically a little faster than my 7A.

Testing the Whirlwind vs. the best Hartzell on an -8 they got around 210 mph. That was on 200 HP. I will be a little surprised if you get 215 on 180 HP, even with the additional 100 rpm.

Anyhow, have fun, be careful and you will love it!

[db1yg]

Hi Luke,

I have an RV9a with the Eci 0360/180 hp and a 2005 version of Craig's 66x76 three blade prop. My lift off rpm is right at 2220 as shown on my AF 2500 digital tach. At 8k density altitude it will easily spin up over 2750 rpm.

Originally I was only seeing around 2160 rpm at lift off and had Craig "tweak" the prop some for slightly more rpm. If you are considering this I would recommend that you wait untill your engine is fully broken in, all the rigging is spot on, and all the fairings and aerodynamic clean ups are complete!!! I was a little quick in tweaking mine and now, due to additional aero clean ups, the airframe needs a little more pitch on the prop.

BTW, if your RPM guage is an analog version from Vans, they are noted for being somewhat inaccurate. Maybe you have a friend who has a portable digital tach that you could use for your testing.

More importantly, be carefull and have fun with the testing!!

Cheers,

db

[elippse]

Guys, I usually see you writing about your speed and rpm at 8000'. I guess that's because 8000' density altitude is usually thought of as where you will develope 75% power. Well, first off, with your forward speed, your manifold pressure will be higher due to dynamic pressure recovery so you'll be at higher power. That 8000'-75% relationship is for much slower planes. Secondly, do you really do most of your flying around 8000'? That's a pretty popular altitude region for C-172 types, so you'll have lots of traffic there. But I would think that you would use your planes mostly for cross-country flights. That's the major reason for my plane, so when I go any distance I fly at 11,500' or 12,500'. It's so much cooler there and there's lots less turbulence and traffic. In the summer, the density altitude here on the west coast is usually about 2000'-2500' higher. The other day at 12,500, OAT was 11C, ISO +20.7C, for a density altitude of 14,880' But if you limit your rpm on a fixed pitch prop to sea-level rated rpm when at 8000', you've really cut into your take-off, climb, and high-density-altitude cruise performance. If you get your prop set-up for rated rpm at high density altitude, you'll see much better all-around performance. Your engine will tolerate, with no problem, going 10% over red-line. Believe me, it won't suddenly explode the moment that needle gets slightly to the right of the red-line. Some of the helicopter versions of these engines will turn up to 3200 rpm. Sure, they might have slightly different parts, but that red-line spec is put on there for certification considerations, not as a "don't exceed or it will fall apart" warning! You do have a throttle, I hope! So get Craig to set up your prop for rated rpm at, say, 14,500' dalt, and when you fly at lower altitude, if the higher rpm alarms you, pull the throttle back a little. The RVs I've tested show a drop in speed and rpm of about 1.1%/1000'. If you get a prop that will turn 2700 rpm at 14,500' dalt, it will turn about 2900 rpm at 8000' dalt, 7.4% over red-line. Now really; when you fly below 8000', don't you pull the throttle to get the rpm at or below rated? OK then, if you get the prop so it will turn rated at 14,500' dalt, you'll just pull it back at a little higher altitude. But then, if you drop it to rated rpm at 8000' dalt, you'll be a little slower but also at less than 75% pwer. So which takes less toll on the engine, the higher internal pressures at higher power, or the higher centrifugal forces at higher rpm but lower power? Typically, over-square engines have more bearing wear from power than from CF. Actually, the piston and connecting rods experience little loading from CF as they are usually being pushed or pushing against a load!

[rvator51]

Thats an interesting idea you stated, Paul. We have a 78 pitch Sensenich prop on our RV-4 due to a good deal we got on it. The normal RV-4 prop is supposed to be a 81 pitch. So what you are saying is that we dont cruise as fast down low but we can let the prop turn faster up higher and cruise faster? We do have the 2600 rpm limitation on the Sensenich prop so we can't go over the 2600 rpm limt at any altitude.

[jrs14855]

If you have ever heard a Pitts or similar aerobatic airplane making a horrible noise, as opposed to a lot of noise, the engine is probably turning around 3500 rpm. There is no history of failures on either the 0 320 or 0360 that can be blamed on high rpm. I ran my Pitts 1000 hours at 3300 plus for every acro flight and as high as 2800 cruise and at 1000 hours the engine still ran like new.

[roadrunner20]

Originally Posted by db1yg

Hi Luke,

I have an RV9a with the Eci 0360/180 hp and a 2005 version of Craig's 66x76 three blade prop. My lift off rpm is right at 2220 as shown on my AF 2500 digital tach. At 8k density altitude it will easily spin up over 2750 rpm.

Originally I was only seeing around 2160 rpm at lift off and had Craig "tweak" the prop some for slightly more rpm. If you are considering this I would recommend that you wait untill your engine is fully broken in, all the rigging is spot on, and all the fairings and aerodynamic clean ups are complete!!! I was a little quick in tweaking mine and now, due to additional aero clean ups, the airframe needs a little more pitch on the prop.

BTW, if your RPM guage is an analog version from Vans, they are noted for being somewhat inaccurate. Maybe you have a friend who has a portable digital tach that you could use for your testing.

More importantly, be carefull and have fun with the testing!!

Cheers,

db

I have the same pitch 66x76 and was < 2200 static on my first 10 hours.
I agree that you need to get the engine broken in and get the fairings on. (you didn't say whether these were installed.) Craig likes to see static+500.
I was shocked how the rpms resumed once broken in & airframe cleaned up.

I see 170-175 kts @ 8500. Sweet spot at LOP is ~165kts @ 8.7gph.

[elippse]

[quote=rvator51;454991]Thats an interesting idea you stated, Paul. We have a 78 pitch Sensenich prop on our RV-4 due to a good deal we got on it. The normal RV-4 prop is supposed to be a 81 pitch. So what you are saying is that we dont cruise as fast down low but we can let the prop turn faster up higher and cruise faster? QUOTE]

As I wrote, if you do most of your flying cross-country at high altitude, get Craig, or me, for that matter, to design a prop for you that turns rated rpm at your highest density altitude, and you'll have more static rpm and thrust, quicker take-off, better rate-of-climb, and higher cruise speed at altitude. But too bad about that heavy Sensenich. With that rpm limitation, you're stuck. I have a friend that has a metal Sensenich 70CM6S9-0-77 on his 150 HP RV-9A and it's a dog in takeoff, climb, and speed, plus he has the bad static port set-up so he thinks he's going 9.4 mph faster than he really is. 189.9 mph IAS-derived TAS vs 180.5 mph TAS from GPS at 2620 rpm, 9520' dalt!

[bobby]

My Catto prop just came yesterday. It will be a while before I fly so I don't have those numbers. I was poking around to see what diameter and pitch others were getting in a Catto 3-blade. I'm in Santa Fe, NM with an airport elevation of around 6400 MSL. Craig made mine with a 68" diameter and a 74" pitch for a RV-8. I ordered it fairly early so it will be a year or so before I get to try it out. Can't wait though and it sure is pretty.