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RV7 W&B Performance???

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Koelemon68

Member
I have a RV 7 with a O-320 FP Catto Cruise prop that I easily get 155-160 KTAS. TO I will get around 2200 RPM but climb is very limited 5-8 FPM at 110-120 mph indicated. It will not exceed 2700 RPM Level flight and any altitude. (Cattos comment to me was "whoever ordered this prop, really wanted a cruise prop) Prop has a 19.2# weight on the front of the crush plate. I believe the total weight on the front with prop is around 23-25#

I have been on here before asking about my aft CG issues. Yes I would love to at least put a CS prop on and/or a 180 HP engine and this would solve all my problems but this engine would have to be taken apart to be able to add the CS prop plus I am working on a -8 for the future. I bought this airplane for a cheaper way for my son to get XC time and TW time while having tons of fun and we really like the airplane.

I am looking a few options:

1. Get a metal 2 blade Sensenich prop. What kind of performance are those with a O-320 getting with this?

2. Getting a Catto 3 blade all around prop. This does not really add but 1# compared to my existing set up. What numbers are those of you getting with the 3 blade catto?

3. As far as W & B goes I also just found out that some put the smaller -8 rudder on the -7 and it helps with the CG and also better performance and handling. Would love more information of this.

Thank you all for your time.
 
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The Catto prop is going to be smoother than the Sensenich -- wood/composite propellers damp out the resonant (or have a much different resonant response) frequencies. Think of the difference when you "thunk" a plastic cup and crystal wine glass -- propellers behave similarly.

The smaller -8 rudder is just a little lighter than the -7/9 rudder. It has heavier skins (.020" vs .016") so that eats up a little of the difference in size|weight.

I put the -8 rudder on both of my RV-7 builds and would do so again. I think the spin recovery concerns that prompted the change to the -7/9 rudder in 2002 were overblown (SB 2-6-1).

Consider changing to an EarthX ETX-680 primary battery. I know it's on the firewall and that won't really help an aft CG tendency, BUT the overall weight reduction is nice.

A hangar neighbor with an O-320 with the Catto 3 blade was getting about 165Ktas / 6000ft IIRC.

Edit: "3 for climb, 2 for cruise" However, RV's climb like a scalded-a$$-ape even with a small engine.
 
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Koelemon68 said:
3. As far as W & B goes I also just found out that some put the smaller -8 rudder on the -7 and it helps with the CG and also better performance and handling. Would love more information of this.
Click to expand...

To increase the strength and flutter margins of the RV-7/7A, remove the RV-9/9A rudder (which is used on the -7/7A) and install an RV-8/8A rudder. The RV-7/7A with the RV-8/8A rudder is a Van's approved configuration.

The post linked below explains why the the RV-8/8A rudder on the RV-7/7A provides larger strength and flutter margins:


Instead of rehashing it all again in this thread, newer forum members can view this thread:

 
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