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Rocket with 3 blade Catto?

R

rv4bill

Well Known Member
I have a Harmon Rocket 11 with a perfectly functioning blended airfoil (J twist).
No issues at all except plane is nose heavy. When full of fuel, or a passenger in back this plane is a dream to fly. 3000 fpm climb on take off and cruise at 22 squared and lean of peak gets me 180 knots at 10 gph. (At 7500 feet)

I am contemplating selling this prop 250 hour hartzell and purchase a new 3 bladed Catto fixed pitch which should drop quite a bit of weight off the nose???

Does anyone know of a rocket out there that had a 3 bladed Catto fixed pitch?

Sure would be nice to get 50 lbs of weight off the nose! I am fully aware I would lose some take off and climb performance but I do a lot of mild acro and want more of that rv4 feel.

How would this prop do in cruise? Would I still be able to dial back and get 21 mpg with a Catto?
 
rv4bill said:
How would this prop do in cruise? Would I still be able to dial back and get 21 mpg with a Catto?
Click to expand...

Most likely you could dial in that parameter, but it would be at the expense of the rest of the flight envelop I suspect.

Any thought to a lighter weight CS prop like MT or WhirlWind?
 
Why not put a 5-8 gallon smoke tank in the rear baggage and stay fast with a C/S prop? Or carry tools, ....
 
Yobo said:
Why not put a 5-8 gallon smoke tank in the rear baggage and stay fast with a C/S prop? Or carry tools, ....
Click to expand...

CS props aren't necessarily faster than FP props. It all depends on the pitch. You can give up climb for cruise speed or visa versa. This is why many of the racers run FP props.
 
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The cheapest, easiest, fastest way to fix this without giving up performance is to carry a jug of water in the baggage compartment. 5 gallons weighs about 41 lbs, plus the container weight and straps. Tie it down good.

Water can be dumped if you ever need to carry pax or more baggage.

You didn't say what handling problems you are getting. I found that 3-points are harder without ballast, so I just wheel land. Other than that, I have no issues over the entire loading envelope. I did, however, move the battery back behind the aft baggage bulkhead, used a PC625 and the standard (heavy) tailwheel.

I have considered trying marine shaft zincs to bolt on the stinger shaft, but haven't felt the need.
 
Catto

I do have an 8 gallon smoke system that fits in the back baggage compartment. When it's in and at least half full, k it does fly more comfortable but you can still feel the heavy nose when pulling up for a loop.

The main reason for the the post was more a question about the Lightweight nickel leading edge Catto. Are there enough advantages to outweigh an already installed and flying hartzell blended? Are there any rockets or IO540 equipped rv's using a 3 blade Catto? How much weight would I drop by switching out the hartzell set up?

I fly into my grass strip (52FA) typically using using only 1500 feet without touching the brakes. When using brakes and a technique taught to by Smokey Ray, I can get in and stopped consistently under 1000 feet. I'm guessing this distance will increase with a Catto or any fixed pitch, but by how much? I'd like to have the prop pitched for cruise and was curious what my rate of climb may drop to? 3000 fpm as set up now with the hartzell.
 
No technical concerns on what you want to do, but your landing and takeoff distances will increase.

Also, your resale value will decline because it's a non-standard config. Have you investigated the 3-blade MT constant speed prop that many Rocket builders use? A bit lighter, I think.
 
A couple things you can try

If you want to change the CG to get better handling solo, you will lose your baggage capacity when 2-up. It's one of those trade-off things.

If you simply want lighter elevators, #1 install a longer stick - have the grip above the bottom of the panel. Adjust the elev push-pull rods to get the clearance from the panel.

#2 install an adjustable elev bellcrank, whereby you can reduce the elev travel and at the same time reducing elev forces.

These two mods are STD F1 parts for the Sport wing so aeros are easier. Seems like you might want the same thing.

If your wallet is fairly deep, the 6 cyl ACE engine will take a lot of weight off the nose; talk to Kevin about this option.

A FP prop is not really the answer for a ship like yours with such a wide speed range. BTW the installed weight of the MT 3 blade is within ounces of the faster Hartzell BA 2 blade, so that option is a non-starter.

Your concerns are nothing new, and there are easy methods to work around the issue. Talk to some experienced Rocketeers to get the full story.

If you need help with any of this, let me know!

Carry on!
Mark
 
Thanks for the info Mark. Not budgeting the lighter engine😄

I do have the f1 sport wing on the Harmon. I'll look into how Art Chard set the bell crank up.
 
Ah yes.... I do have a long stick and modified bellcrank on my Rocket, so i have a much lighter feel with a longer throw.

So if it's pitch forces that are the issue, this helps a lot. If you are running out of trim, check that you have rigged the trim tab according to Van's specs. You need a lot more up trim than down trim.

You haven't really detailed what handling issues you have, so we are shooting in the dark a bit here...
 
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