CS Prop vs Fixed

I have read many of the posts about props, but am still having trouble making the decision regarding type of prop to put on my RV-9A. I have been planning CS all along, but now as I look at the difference in cost, and hear people talk about being happy with props such as the catto, I am beginning to wonder.
Can you help me out with some advice and perhaps personal experiences?

Thanks

Neal Powell
RV-9A in progress

If cost is high on your list of considerations, clearly the CS is way more expensive to install and maintain. However, it does provide a special kind of launch and climb that can't be matched by the usual fixed pitch. I enjoy the little added excitement of "blast off". But I could afford it, so that is what I did.

Go Constant speed

I have not had the pleasure of flying a 9 but I do have my 8
Go for the C/S prop, I know it costs a bit more and is more maintenance but it is worth it. I know of at least 6 different RVs that started Fixed pitch and changed to C/S and all of them said they wish they would have just started with the C/S.
Best of Luck!

A while back I tried a little experiment because of this very question. My 9A has a CS Hartzell, but so many people ask this question that curiosity got the better of me and I had to know. At Watsonville, CA a few circuits of the pattern seemed like the right thing to do one day so what the heck. Being careful to trim for an exact airspeed on climbout a couple of laps around the patch were perfomed to see the exact vertical speed of the climb. Then on downwind I set the prop for 2300 rpm and left it there on landing and taxi back, etc. The take off and climb out was then tried with this setting of 2300 which is pretty typical of a fixed pitch prop on takeoff and the climb dropped from the 2000 fpm range to 1400-1500 fpm. The take off roll was longer, but not dramatically.

Now add some time and the a trip with another RV-9A. This would be Leland Collins 9A to be exact which has a 3 bladed Catto. We made a fuel stop at Bakersfield and then departed to the south which gives about 30 miles or so to get to 9,500' to get over a mountain so we were climbing out aggressively. My wife and I along with baggage were in our plane, and Leland and his bags were in his. As we climbed out at these differing weights Leland and his Catto prop were out climbing us!!! It was really impressive to say the least. I took off first and he beat us to 9500 by about 700 feet or so. That is the only fixed pitch prop that has ever done this to us on a climb, including RV's with 0-360's. The next leg of the trip Leland had a passenger and the weights were more similar to ours and the results flipped on the climbs, but that is not a slam. The performance of the Catto was so incredible that it was hard to believe. This prop has cut well into the perfomance gains of the CS while maintaining the simplicity of a fixed and the weight advantage to boot.

So there you go, good luck trying to make a choice. It'll be a win win which ever you choose.

Best,

I was talked into a C/S by my tech advisor while building my 6. If you can afford it do it! It allows you to get full hp out of the engine at takeoff and while landing acts as an excellent brake. I would never consider going back.

Doug
RV6 180hrs

An RV with a fixed pitch prop is a great joy to fly-----until you fly one with a constant speed. Once you do, you do not want to go back. I flew my 180hp RV6 for 1400 hrs with a fixed pitch and was in heaven and thought the performance was great. Then it happened, I flew an otherwise identical RV6 with a c.s. prop and it bit me hard. It took an engine and cowling change (solid crankshaft and the old 4"extention cowl) to do it but I had to do it and never looked back. Of course my new 7A has a c.s. prop too.

Martin Sutter
building and flying RV's since 1988

I flew a 9A with a 150hp engine and Hartzell C/S. Out of a 4200' msl airport, the climb performance was at least twice that of a Cessna 172 with 2 people.

It could also do a remarkable job of coming down steeply, thanks to the "braking" effect of C/S, as well as slowing down quickly, when landing "with the wind" (to a certain degree); for landings on some "one way" air strips.

Needless to say, the builder that built that plane (was a partner), is building a new one for himself that is constant speed & a 320.

L.Adamson -- RV6A 0360 & Hartzell C/S

Go C/S Hartzell BA!!! You will be happy. I am.

Roberta

npowell said:

I have read many of the posts about props, but am still having trouble making the decision regarding type of prop to put on my RV-9A. I have been planning CS all along, but now as I look at the difference in cost, and hear people talk about being happy with props such as the catto, I am beginning to wonder.
Can you help me out with some advice and perhaps personal experiences?

Thanks

Neal Powell
RV-9A in progress

Click to expand...

Neal-

My .02 is that it really comes down to priorities re: what you want to do with your money.

As others above have said, an RV with a fixed pitch (espec. Catto) will perform far better than anything you've probably flown before. I flew a C182 with constant speed (out of KSFF actually) for a number of years and loved the constant speed, especially for the braking. However, I'm going with a 2-blade Catto because I can't rationalize spending $5-7K more on my already expensive hobby, even though I can afford it.

Big caveat--I'm currently waiting (this week) for Aerosport to call me to say they've found an 0-320 with a hollow-core crank to overhaul for me... just in case I ever want to upgrade to c.s. down the road. Even though I have no plans to do so, I'm conservative enough that I always want to reserve the option to change my mind.

As you probably already know, one of the most insidious aspects of this hobby is that there are mulitiple ways that you can spend more money, even if you don't really need to.

Good luck.

Neal, I had an -9a with an MT, but because I fly out of a short strip. I needed it for stopping. It helped on takeoff also, but only when the grass was soft.

My own view is if you have the money to spare, buy an MT C/S, because it is really smooth, but if you have other financial pressures, and fly off a long hard runway dont bother.

You can see my 1020' of grass here.
http://gikonwhy4.blogspot.com/2006/05/why-did-i-choose-to-build-rv4.html#links