Geico266

Geico266

Well Known Member
Can you run a Catto prop in light rain without hurting it?

Any experience flying in rain with the Catto??
Any damage?
What RPM range did you reduce to?
 
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Here's what one guy did

Mike Thompson and I have an ongoing personal competition in the RV-Blue racing class. He has an RV-6 and I have an RV-6A. Initially he beat me in 2007 but with drag reduction mods I passed him toward the end of that year and he has never beaten me since. He has been very busy modifying his airplane in an effort to regain the lead position. One of the mods was the replacement of his Sensenich metal prop with a Catto prop. At the first race this year in Taylor, Texas he his plane had the wingtips cut off at about 3" and plexiglass tip plates installed along with the Catto Prop and goodness knows what else. We took off in sequence and he stayed right there - at each turn I would make my turn call and he would make his right after me. There was light rain in the next to last leg before the turn around a radome north west of Granger Lake. When I made my turn call he was no longer "right there". He pulled back and deviated from the direct course to avoid erosion of his Catto prop. If you go to www.sportairrace.org an go through the Race Memories link you will find his GPS track for the 2009 Taylor 100 Air Race showing the area of rain and the amount of deviation he made to protect the prop.

Bob Axsom
 
One opinion!

If you are into racing and all out full bore flying, then Bob is right. On the other hand, I have run many wood props -- on several airplanes -- and currently a 3-blade Catto. I have NEVER had to refinish a prop due to rain erosion. Now I don't fly through rain a lot, even though I have gotten caught many times. Generally I try to avoid it. If caught in it, I do pull back the rpms. Usually this is for a very short period.
I've heard stories all my life that "You can't run a wood prop in the rain." Bottom line, if you plan to fly a lot of IFR and/or racing, this may be true, but I have not found it to be a problem in over 25 years.
 
direct from Craig

If you put the leading edge tape on all blades, the rain restriction is lifted.
 
Also direct from Craig Catto...

From an email dated 6-April-2007:

"The only real option is pretty much any color you want, and the application
of PropGuard Tape. This tape will allow you to run full throttle through
rain. Without the tape you need to pull back to 2300 or so without any
erosion."
 
Is the tape permanent or do you keep an eye on it and replace as necc? Do the blades ever "throw" the tape leaving you with differing aerodynamics/weight between blades? How long does the stuff last? Where do you get it?
Did I use up my alloted questions yet? <BG>

DM
 
The tape is called PropGuard. You can get it at Aircraft Spruce or any of the aircraft supply houses. Never heard of it being "thrown" off. Mine has been on for several years. Many high performance airplanes use it. Of course, being on the prop, you will always "keep an eye on it."
 
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Thanks Mel

Mel said:
The tape is called PropGuard. You can get it at Aircraft Spruce or any of the aircraft supply houses. Never heard of it being "slung" off. Mine has been on for several years. Many high performance airplanes use it.
Click to expand...
 
Thanks Guys.

Also, I e-mailed Craig Catto and he said pull it back to 2300 and you are good to go.
 
I had a bad experience a few years ago with my (then new) Catto. On a flight back from VA I spent about an hour in the soup and light- moderate rain. I had the power up (2600 RPM or so) the entire time. I assumed that the fiberglass prop, coupled with the small diameter (hence lower tip speeds) would be OK in the rain. Boy was I wrong! When I landed, the amount of damage to the leading edges was quite surprising. Enough that I sent it back to Craig to be reworked.

To be fair- this was my own stupid fault, and not a knock on the prop. I did not have the Propguard tape on it at the time (do now!) and ran it too hard in the rain. Now I throttle back to 2300 any time I'm in rain, and I've had no further problems. With the tape I could probably push it up a little more, but I'm not interested in pushing the issue.
 
I find it interesting that only 300 RPM makes the difference between damaging the prop and no damage.
 
Mel said:
Think about the prop tip speed. A little RPM goes a long way.
Click to expand...

Which is because Kinetic energy = 1/2 x Mass x Velocity(squared)...

A 10% increase in tip speed (or RPM) results in a 21% increase in impact energy on a prop tip. A 20% increase in tip speed results in a 44% increase in impact energy.

Which is why I throttle back to <2000 RPM in rain. RPM is the only thing (other than rain avoidance) that can minimize the damage. Even at 2,000 RPM, light rain will remove the paint from the leading edge at the prop tips.
 
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Prop Guard

A little over a 100 hrs here on a new Hartzell 2 blade with Prop Guard. Somehow, visible moisture got under Prop Guard 1st flight thru rain, now has mostly dissipated.

Only other comment is subsequently had a cracked prop spinner backing plate, around 3 of 4 attach bolts, with a then non Van's spinner assy.

I do not know if these two events are related, re prop balance.
 
might be a stupid question

But does putting a prop guard on make it less efficient?

Randy 8A
Finishing, FWF,
Baffles, Painting,.............
 
Kyle Boatright said:
Which is because Kinetic energy = Mass x Velocity(squared)...

A 10% increase in tip speed (or RPM) results in a 21% increase in impact energy on a prop tip. A 20% increase in tip speed results in a 44% increase in impact energy.

Which is why I throttle back to <2000 RPM in rain. Even then, light rain will remove the paint from the leading edge at the prop tips.
Click to expand...

Good point!

But the equation is actually:

KE = 1/2*mass*velocity(squared)

Note the "1/2" term. ;)
 
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