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RV-7 and Cato Prop weight advice.

gonzaviador

I'm New Here
Hi Group. I want to ask some questions related to the Catto prop use in a RV-7 and the effect that it has on the CG, and how to address it. I know that a lot has been written about this issue, so is not my intention to start a new tread on it. My engine will be the Aerosport Power IO-375.

My first choice would be the Aluminum Hartzell, but the only issue that I have with it is, since I'm in Chile, I don't have an authorized Hartzell repair facility here (although there are many maintenance facilities that can do the job), and want to avoid the regular maintenance schedule and costs.

I've read that many of the ones that have used a lightweight prop had cg issues, but other seems to be flying fine with no issues, so I'm a little puzzled.

In short, my questions are:

- There is a way to use a Catto Prop in a RV-7 and don't have CG issues? How? (heavy crush plate, extension, and so on... where do I purchase such items?)
- The use of the Catto will require some kind of mod to the cowls or other part of the airframe?
- Does the prop has a regular inspection schedule? can be performed by yourself or do you need a maintenance facility to do it?
- If little damage occurs (nicks), there are guidelines to verify yourself if it still airworthy? Can this little damages be repaired by yourself?

Thanks a lot for your advice.
 
Heavy crush plate ...

Hello,

My buddy is running a Catto prop with a 14lbs crush plate to keep things aligned. Nicole at Catto organized it from Sabre Manufacturing.

Works fine!
 
Not sure how far along your build you are, but I'd tell vans you have a 0-320 and get the motor mount for that. From what I understand it's an inch longer. Better to push the weight out than add extra weight. Unless your plane is VERY light...

Let us know what you come up with.
 
Saber Manufacturing

I wasn't aware of another motor mount option and went with a 20 lb Saber plate on the front. Works great and my CG is well within the aft limit with me at 210, a passenger at 190, full fuel and 50 lbs of baggage. With a lighter or no passenger, I can max out the baggage compartment.

Mine is a -7A, which may differ a little.
 
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I used the 320 mount, need to order 360 cowels unfortunately you'll have to graft about 1.5 - 2 inches on the cowels to give them enough length, Would I do it again? Maybe... Probably, putting a light weight prop on then bolting 20lb of dead weight behind it, kinda an afterthought.... But that way with the spacer does allow you to more easily convert to a metal CS in the future.
 
Thanks.

Thant you very much for your advices. After doing more research locally, I've decided that going with the Hartzell CS will be the simplest way to go.

Thanks again.
 
I'm flying behind an IO-375 with a catto 3-blade. My plane uses a 14lb crush plate.

WRT "derating" of the engine: the catto is the smoothest prop I've ever used; I'd be tempted to go with it for that reason alone. But beyond that, I just don't see the issues that get talked about endlessly on VAF -- my climb performance is excellent, even at the high elevation of my home field; cruise is very comfortable at 165kts and 60% power; and I have no issues slowing down.

I'm sure I could eek out a bit more with a CS prop, and I do wish I could take advantage of the 3 blade without the heavier crush plate, but as far as the 375/prop combination goes I'm very pleased.

Did I mention the looks? It looks amazing -- and we all know that makes it faster.
 
Hi Dan.
What is the takeoff distance and landing distance with the catto on the aerosport? Thinking the same combo myself but will be operating of a short grassstrip, 450yards.
Cheers
 
This morning I measured the take-off and landing roll. My plane weighs 1046lbs, and was carrying me (180lbs) and my friend (200lbs), no bags, and about half fuel. Field elevation is 5500ft and the surface is asphalt. The prop is set-up for climb side. This morning was ~70F -- altimeter setting 29.94.

Take off was just within 450 yards using short field technique. After that climb was a healthy 1600fpm.

Landing roll was about 300 yards, and I was going easy on the brakes.

I'll try again in the next few days with just me in the cockpit.
 
Thankyou Dan. I was hoping the takeoff run would have been shorter. I may have to look at the cs prop, 450yards would be too long for my strip. Its a shame as I have heard such good reports on the catto.
Miller
 
Get a CS prop

FWIW, a CS prop is some of the best money I spent on the project. Like zilik said, what's the point of building a hot rod, then limiting it's performance with a fixed pitch prop.

It should pay for itself in fuel savings, durability, etc over time as well.

Edit: Let me add that the -7 is designed around the O/IO-360 and Hartzell CS prop. So if you go that route, you'll be using a proven design. And, your W&B will be right in the center.
 
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This morning I measured the take-off and landing roll. My plane weighs 1046lbs, and was carrying me (180lbs) and my friend (200lbs), no bags, and about half fuel. Field elevation is 5500ft and the surface is asphalt. The prop is set-up for climb side. This morning was ~70F -- altimeter setting 29.94.

Take off was just within 450 yards using short field technique. After that climb was a healthy 1600fpm.

Landing roll was about 300 yards, and I was going easy on the brakes.

I'll try again in the next few days with just me in the cockpit.
Seriously? When Vans publishes 300 FT takeoff and landing is 350 ft. Takeoff in 450 yards is 1350 feet.
 
Seriously? When Vans publishes 300 FT takeoff and landing is 350 ft. Takeoff in 450 yards is 1350 feet.

Seriously? I doubt vans published numbers are for over 6000ft DA and a fixed prop. Could be wrong though....

Correct.

All published specs are for a zero wind standard temp day at sea level.
If they weren't, then the numbers could be massaged into what ever could be attained on a very cold winter day here in the PNW (we have lots of airports close by that are just barely above sea level) when the wind is blowing like crazy.
Many of the specifications are also with a specifically stated engine / prop. combination. The take-off distance difference between two identical airplanes other than one having a fixed pitch cruise prop and the other having a constant speed, can be quite large.


BTW, a standard sea level temp. and pressure (if I am remembering correctly) is 59 deg F and 29.92". If you are in conditions that are different from a density altitude of zero at sea level and that pressure and temperature, the performance results will be effected.
 
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Thankyou Dan. I was hoping the takeoff run would have been shorter. I may have to look at the cs prop, 450yards would be too long for my strip. Its a shame as I have heard such good reports on the catto.
Miller

I haven't done specific measurements on a standard day but I am very happy with the performance of my Catto. Along with that is a fraction of the price up front, simplicity of operation and no maintenance headaches you'll read about here (on some, not all) CS props.

If a good quality CS prop is in your budget, you will have better climb performance but not likely much gain in top speed.

I found a great deal on a O360-A4M so a CS prop was never a consideration thanks to a robust solid crank shaft.
 
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