"Asking for a friend....."
Hahahahahahha
Love it.
Fit a C/S prop and enjoy the full fun that an 8 can provide
I'll get my coat.....
fixed pitched props with a 360 - cruise speeds and climb rates
My specs are:
Engine: Superior IO-360-M2S with dual PMag
Prop: Catto 3 blade, 68" diameter, 76" pitch
75% Power:
@3000ft: 2510rpm / IAS 156kts / TAS 165kts / 24.4" MP / 8.9 usg/hr
@6000ft: 2610rpm / IAS 159kts / TAS 174kts / 22.8" MP / 9.1 usg/hr
55% Power:
@3000ft: 2220rpm / IAS 136kts / TAS 144kts / 20.1" MP / 6.8 usg/hr
@6000ft: 2220rpm / IAS 134kts / TAS 152kts / 19.1" MP / 7.1 usg/hr
Those are measured values of my flight testing... But not yet lean of peak.
Then also the climb performance as well as takeoff and landing performance. But they were done when I did not yet had to much experience (below 30 T/O and LDGs in total) thus they may could be improved.
Regards,
Yves Heller
Actual cruise numbers: RV4 rather than RV8, but relatively similar - O-360, standard compression, fixed pitch Sensenich carbon fiber prop pitched for 2700 at wide open throttle, so cruise setting I guess. In the pic below, 2560 RPM, 19.7”, 64% power, 9,500 feet, 8.8 gph, 172 KTAS. This is not at wide open throttle. WOT at this altitude would still give me 2700 RPM.
View attachment 18489
A properly pitched FP prop for top speed or other specific configuration has two advantages. Weight is the obvious one, and no prop governor. I'm sure the governor isn't taking huge amounts of power, but it's not zero either. It would be interesting to know it's exact requirement.
Yup, this is why I went with fixed pitch Catto. Except for showing off on climb out, my flying doesnt entail 500 foot strips with 150’ trees at each end. But I am sure once I visit Johnson Creek with my new plane, that will change. ( Bring on the -15!)Also, a C/S prop is the most expensive single item on your aircraft to maintain, if maintained i.a.w. the manufacturer.
Cross country cruise in RV8 with Superior IO360 and Catto 3 blade I get 162 ktas at 2460 rpm and 8.2 gph at 5000 density altitude. 2700 rpm equals 178 ktas, more if I'm willing to exceed 2700 rpm. First photo is 178 ktas at 16000 density altitude. Second shows 30 + statute mpg at about 12000 density altitude. Don't buy the one gear thing. My turf airfield is at 155 feet msl and when I'm light, I can go from standstill to 1500 feet in one minute, more when temps are cool and less in hot summer temps
For the guys running fixed pitched props with a 360, what kind of cruise speeds and climb rates are you seeing?
Anyone running a 3 blade FP?
Asking for a friend.
I have never driven a dump truck, but now I want to give it a go, if it's as fun as my RV-8!Placing a heavy FP prop, gadgets, or fat pilot/pax on an RV 3, 4, 6, 7, or 8, makes your RV handle like a dump truck.
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Placing a heavy FP prop, gadgets, or fat pilot/pax on an RV 3, 4, 6, 7, or 8, makes your RV handle like a dump truck…
The OP is looking for real world numbers.
Answers to the original question will help someone make an informed decision, including myself.
With the recent 13% increase in engine cost it’s conceivable that may have blown the build budget for many. The previously planned C/S prop is the place to make a big cut.
Generally speaking, one of the greatest challenges around here is getting your actual question answered...
From memory so don’t hold me to it.
- RV-8A with Sensenich FP prop, 180hp IO-360, 2600 RPM at 4500’, 165 kts. I limited RPM to 2600 so it could go faster if I tolerated the excessive RPM.
- Same RV-8A with Hartzell CS prop, 2500 RPM at 4500’, 175 kts (and about a GPH less fuel burn LOP).
Carl
Hi Carl,
Thanks for the numbers. Did you notice a significant difference in climb FPM performance?
For example, loaded near gross and climbing to 8000 to 10,000ft
I'll be posting some results later this week as I go from the Sensenich 2 blade metal FP to the Catto 3 blade carbon FP. I have been happy with the performance of the Sensenich, but it's a bit heavy and the Catto just looks so sexy. Before I get any comments on why.... I bought the plane with the Sensenich installed and the Catto boxed up for refurb. I sent the Catto to them for refurb and the cost just made sense. I LOVE the way the 3 blade looks, I wouldn't mind shedding some weight and from the folks I have talked to the carbon 3 blade runs so smooth.
If weather permits I'll fly out to Catto tomorrow for the switch or if the fog sticks around, later this week. I'll get performance number on the Sensenich on the way out and the Catto on the return flight. Should be interesting to compare the 2 back to back.
Quite curious how the RV 3 handles with a fat pax? I'm sure it would be fine with the weight of a nose gear, a constant speed prop, but no primer.
Not really relevant. Don’t think you would buy a car with a air cooled engine or only tuns 2700 rpm.would I buy a car with only one gear?
Placing a heavy c/s prop on an RV 3, 4, 6, 7, or 8, makes your RV handle like a dump truck.
I have been flying my RV8 which I built for 10 years. I had a Catto 3 blade for 7 of those years with a 0-360 180HP motor cruising 170 knots at 2500 rpm. I now have a BPE built IO-360 200HP angle valve motor with the Hartzell 2 blade composite constant speed prop cruising (2400 rpm) 190 knots usually at 6500-9500 msl.
My CG was very far aft with the light Catto prop as it was hard to load without the CG moving very close to the aft limit with a passenger and baggage. Between the motor and prop I added 66 pounds to the nose with the heavier angle valve motor and constant speed prop. I now add weight (25lbs) to the aft baggage compartment when flying solo.
In my opinion the airplane is much more stable with the forward CG. It is also much easier to load with a passenger and baggage and the CG ends up in the middle of the envelope. An added benefit of the more forward CG is the airplane lands much easier in my opinion.
My plane absolutely doesn't fly like a dump truck! Ridiculous statement in my opinion!
Kevin
Very true! The EIGHT never should have been on that list. How does it handle without the 25lbs in the aft baggage?
I couldn’t be happier with my current set up! I know the Hartzell Composite prop price is a deal killer for many! I’m fortunate to be able to pull it off! However I can’t imagine an 160hp RV 6 out running my RV 8 with the Catto prop cruising 170 knots!