T

TShort

Well Known Member
I am still a ways away from engine / prop, but remain very torn about CS vs FP. I like the idea of the simplicity and light weight of a CS prop, but the performance of a Whirlwind CS prop is enticing.

I'm working on the fuse and thinking about throttle quadrant, etc., so I started thinking about choices again.

Anyone out there flying an -8 with an IO-375 and Catto 3 blade prop? Any feedback?

Thanks

EDIT: Yep - what I meant above was "simplicity and light weight of a FP prop". See what happens when I try to think about too much in the middle of a night shift...
 
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Seems to me that a high horsepower engine would need a constant speed prop to make full use of its power. A fixed pitch prop would overspeed at full power, so you'd have to throttle back much of the time to avoid that.

That's my theory, but am happy to be corrected if wrong.
 
Why not ask the man?

Call Craig and ask him.These are all hand crafted beauties, well,....Hands on CNC Marvels.The racing world is all about weight/power. Its done all the time just not in great numbers.And we all know there is Safety in numbers.Whirlwind makes a ground adjustable same blades another great choice.
RHill
 
Confused?

TS and Grayforge,

You both seem a little confused about this.

TS you say you like the light weight and simplicity of a CS prop.... is this a typo CS are generally heavier and more complicated than FP.

Gray..... a constant speed has benefit of both low and high power engines because it allows max power to be produced from static all the way up to cruise. A FP is compromised somewhere depending on how it is pitched.

I love CS, but I also think the Catto is a really really good CS and am considering replacing my Sensenich on my 4. W and B is also a consideration with props.
 
Confused?

"but I also think the Catto is a really really good CS"
Confused or a typo? Easy done, hey Steve :p

Paul.
 
I built thinking I would just go with a Catto for a year or two then "upgrade" to a CS.

100hrs now and the only time I would enjoy a CS over my Catto 3Bl prop is pointed straight down after messing up an aerobatic sequence. Nothing but prop speed braking to halt the airspeed build up.

My Catto Prop redline is 3300rpm... Your not going to overspend a Catto prop.

Every other stage of flight I will bet money on the Catto with your engine.

Hate to sound like a "Fanboy" regarding the Catto. I don't want to be a FP guy, but cattos prop kinda forces you into that situation. :rolleyes:

"Simplistic is the ultimate form of sophistication", I stole that from some smart guy. :D

I have a io360 with HiComp pistons that should be close to your io375.

***this is not a 2400rpm cruise prop. The Catto performs when "spun-up".

Regards,

Scott
 
Every other stage of flight I will bet money on the Catto with your engine.
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I believe you would lose that bet. One benefit of a CS is that it allows the engine to remain at its max power RPM regardless of airspeed. A fixed pitch simply can't do that. The Catto's are beautiful, but they can't circumnavigate the laws of physics. If it's set for cruise speed, your buddy with the CS will have to throttle back to wait for you in the climb and until you reach that cruise speed.
 
ColoRv said:
I believe you would lose that bet. One benefit of a CS is that it allows the engine to remain at its max power RPM regardless of airspeed. A fixed pitch simply can't do that. The Catto's are beautiful, but they can't circumnavigate the laws of physics. If it's set for cruise speed, your buddy with the CS will have to throttle back to wait for you in the climb and until you reach that cruise speed.
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Here we go...

I'm very aware of your statement. I don't fly below 80-90kts except for takeoff and landing. After that the props are spinning pretty close. Now then again, I get to haul 50lbs less into the air. It's not just black n white.

*** in cruise I get to spin her up to the degree that a CS prop would need a teardown and rebuild.

Looks alone adds 20kts! :p

14c68a37cba63a230aa0cdb46196fb82_zps5b5c7203.jpg


(I'm also of the Jarhead clan) nice to meet you.
 
Rhino889 said:
Here we go...

I'm very aware of your statement. I don't fly below 80-90kts except for takeoff and landing. After that the props are spinning pretty close. Now then again, I get to haul 50lbs less into the air. It's not just black n white.

*** in cruise I get to spin her up to the degree that a CS prop would need a teardown and rebuild.

Looks alone adds 20kts! :p

14c68a37cba63a230aa0cdb46196fb82_zps5b5c7203.jpg


(I'm also of the Jarhead clan) nice to meet you.
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Jarhead are ya? Well met Devil Dog. So, we both have angle valve high compression engines in RV8's but we went different ways on props (whirlwind here). Being that I'm from Florida and my soon to be flying project has a primary mission of taking me to lunch at Cedar key...I suspect you and I will get to test our hypotheses in the future. I can't for the life of me wrap my head around a fixed pitch being at its max power at 90 knots and still there at 170 knots but I'm open minded. I suppose if you're climbing at 2700 and spinning much higher to keep up in cruise....but aero sport would advise against that. That's an expensive engine to wear out early. Win or lose, I'm very much looking forward to seeing the coast of home below my wing.

That is a gorgeous plane!
 
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Superior IO 360 and Catto 3 blade on my RV-8. I can meet or exceed all Van's numbers posted for the CS RV-8. But the CS initial rate of climb is higher until about 110 knots and if I want 75% power at 8000 DA, I have to turn 2700 RPMs. So my usual cruise is more like 162 KTAS at 8000 DA and 2450 RPMs burning about 8.5 GPH rich of peak. For dash speeds it is a little quicker than many of the CS RV's when I exceed 2700 RPMs. Cost of acquisition and ongoing maintenance is much less for a fixed pitch prop and there is a weight benefit as well. So it is definitely a trade off with advantages and disadvantages to each. I too thought I would run the fixed pitch for a few years and then switch to a CS. But now I am happy with what I have.
 
Only 17 hours so far on my RV7 O-360/3 bladed catto prop 2nd gen but I'm really impressed. Like others have said, the only noticeable performance gains are below 100ish knts. Takeoff over a 50 ft obstacle is easily less than 1000 ft with the fixed Catto. I have no problem flying with the constant speed guys so far, especially if I climb at 135 knts. I can't wait to get the leg fairings on and see what happens!
 
Beautiful, clean-looking airplane from the front. My compliments. How about a shot or two from the side?

What RPMs are you getting at full throttle in cruise?


Rhino889 said:
Here we go...

I'm very aware of your statement. I don't fly below 80-90kts except for takeoff and landing. After that the props are spinning pretty close. Now then again, I get to haul 50lbs less into the air. It's not just black n white.

*** in cruise I get to spin her up to the degree that a CS prop would need a teardown and rebuild.

Looks alone adds 20kts! :p

14c68a37cba63a230aa0cdb46196fb82_zps5b5c7203.jpg


(I'm also of the Jarhead clan) nice to meet you.
Click to expand...
 
precession said:
Beautiful, clean-looking airplane from the front. My compliments. How about a shot or two from the side?

What RPMs are you getting at full throttle in cruise?
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8000DA LOP is 2750rpm full throttle
8000DA ROP is higher at full throttle (Racing power) see you guys at sun n fun dash 40!

Thank you

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066c701b4a4c578aaca4019fcd5fa766_zps51dd61cf.jpg



2eac1a1caf2253118223d58a890eb67c_zps24275283.jpg
 
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ColoRv said:
. . .I can't for the life of me wrap my head around a fixed pitch being at its max power at 90 knots and still there at 170 knots but I'm open minded. . .
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Hey Bill, your camping neighbor from Oshkosh a couple of years ago (Mary and Steve), red and white 9A.

Perhaps a FP prop RV will not necessarily be at MAX power at 90 and 170 KTS but it is at pretty optimal performance levels for climb and cruise for these RV's. I have been flying with a 3-blade Catto on my 180hp 9A since first flight. I have now flown multiple hours along side a couple of RV7A's with CS props. What I have basically seen is that the primary area where they outperform me is when they go to slow down and/or descend. They can literally SLAM on the brakes where I have to manage my inertia. Otherwise, I can pretty closely climb with them and, most definitely, cruise with them wing tip to wing tip. And I might add, this is with a prop that I have been working with Craig for 1.5 years now to change because I believe it is under pitched for my airplane. I am anxious to see what will change once he finally ships me a different pitched prop.

Perhaps the thing to consider is that your thinking may be caged by a paradigm in which you are trapped. Consider the possibility that there could be a paradigm shift occurring that is fed by things such as props being constructed with new materials and the subsequent properties of those materials that were never considered viable before now. These materials could be providing for practical functionality that was never considered possible before with older design shapes and traditional materials.

Yes, CS props have a lot going for them when considering performance. That is except for expense, weight and maintenance requirements. However, the FP props Catto is producing are coming so close to matching the CS prop performance that the expense, weight and maintenance requirements of the FP are beginning to show there may indeed be an advantage to flying behind a FP prop.
 
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