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badmrb

Active Member
I recently purchased an RV6a with a o-360, 10:1 pistons, 1 mag, 1 electronic ignition and supposed to be about 200HP. Just had a top overhaul done before purchase and only about a dozen hours before the Aymar-Demuth wood prop came apart. (see my other post)

Ed Sterba was nice enough to build me a prop on short notice and I just went with his suggestion for pitch. Its 70in by 86 pitch. He said it was A LOT easier to take some pitch off than add to.

I put the new prop on and flew home a couple days ago. I decided to do some performance runs like I've been reading folks do and get a baseline. I wish had done something similiar before. All I have is a rough idea of what my numbers were.

Static on the ground was 2300. Had to go for a distance to clear overcast. At a couple thousand feet and wide open I was getting 2600 rpm and about 160kts IAS. After clear of the low ceiling I started my climb to 6500ft for a circuit. Climb was weaker for sure. Full fuel and solo was only getting about 1000fpm climb at 6000ft and 120kts IAS. Before I was getting more like 2000fpm. I KNOW before with full fuel, me and wife, and 120kts IAS climb we still were maintaining about 1500fpm climb through 6500ft.

So, I know climb is diminished.

Did a GPS circuit at 6500ft with OAT of 50, WOT with 2590rpm, and 100 ROP I was burning 10.9GPH and showing 155kts IAS. Flew the compass for about 5 miles each direction. N- 175kts , S - 147kts, E -157kts, W- 161kts .. . so ground speed averages out to 160kts.
I wish I had solid numbers but it seems like before at about this altitude I was turning 2500rpm,(not WOT), 155kts IAS and burning 9GPH. I never did a WOT or a circuit. . . but I know if I leveled out after climbing I could see over 2600rpm before pulling power back and leaning.

Climbed to 8500ft and did same circuit. OAT was 46, WOT gave 2560rpm and 9.8GPH with 145kts IAS. N - 174kts, S - 141kts, E - 155kts, W - 167kts so ground speed average of about 159kts.

I guess I need to know how this compares with other guys running similar HP.
And if anyone is running a Sterba I would love to know what pitch is giving them the sweet spot on performance. I will be ordering a replacement MP sensor so I have some idea what that is but Im sure I'll be having SOME pitch taken off. I just need to know how much or what others with similar setups have seen for performance changes using different props.

Thanks
Steve
 
On my RV-6A O-360 before I made it close to 200 HP I could get right at 2700 rpm WOT at 8000' DENSITY ALTITUDE.

Seems like the TAS was around 197 mph with a Aymar-Demuth 2 blade prop. That may make the comparison pointless.

I will try to get the specs on it tomorrow for what it is worth.
 
With my Aymar/Demuth on the 160 hp RV-6, I get ~172 knots at WOT at 6500' and near standard temperatures. That's at 2625 rpm...

My prop is biased towards cruise. Solo, I get 1500 fpm at lower weights and 800-1000 fpm at 1675 lbs and 90F.
 
My Aymar Demuth was a model 3600 and 68in by 81 pitch. It definetly was giving better performance. The climb rate had to be almost double and maybe 10 knots better in cruise with similar fuel burn.

I would replace it with the exact same prop if I was sure of the reason for failure. I've thought of getting another AD prop with the carbon fiber overlay hoping it would prevent a similar failure. I dont know.

I'll get this one repitched before making a final decision. I'm just curious what others are doing with similar setups.

If you know what size/pitch and airfoil model. .. please post it along with your performance numbers.

Thanks
 
badmrb said:
My Aymar Demuth was a model 3600 and 68in by 81 pitch. It definetly was giving better performance. The climb rate had to be almost double and maybe 10 knots better in cruise with similar fuel burn.

I would replace it with the exact same prop if I was sure of the reason for failure. I've thought of getting another AD prop with the carbon fiber overlay hoping it would prevent a similar failure. I dont know.

I'll get this one repitched before making a final decision. I'm just curious what others are doing with similar setups.

If you know what size/pitch and airfoil model. .. please post it along with your performance numbers.

Thanks
Click to expand...

I am only mentioning this since it sounds like you did not build the airplane...

When you removed the damaged prop was it slightly blackened/burned on the aft face of the hub? It will actually smell a little bit burned if you sniff the wood on the back. The reason I ask is because not a lot of people seem familiar now a days with the maint. required on wood props. The attach bolt torque needs to be check occasionally, particularly when there is a major weather change (like from a humid to more dry time of year).

I am aware of a number of different wood prop failures that were actually caused by the prop getting slightly loose. This seems to be more of a problem the higher the power output of the engine. I still have a video of a friend crossing the finish line of the Sun 100 many years ago with a wood prop that was in the process of coming apart. I still get chills thinking of the sound it made on the video (I didn't hear it in person, I was ahead of him in the race).

Just something to consider...

One other comment...you may not be aware (since you didn't build the plane) but the moment you installed a different propeller than what it had when you bought it, the airplane reverted back to it's phase 1 operating limitations and you most likely were not legal to fly it home or with your wife on board. Just FYI...
 
Not my first rodeo.

Thanks for the heads up. . .but not my first rodeo or airplane. .. or experimental. It is my first RV. Hub was torqued correctly. No burns etc. Lost wedge shape from the tip and posted a pic on another post.

Wife has not flown with me with new prop or after putting back into phase I. She however was with me when prop came apart . . .but didn't seem interested in getting out of the airplane at 7000 ft so. .continued flying the no longer airworthy airplane with a broken prop until I landed, and then I let wife out.

I would still like to hear what folks with a rv6, o-360 and wood prop are getting for numbers, cruise fuel burns and airspeeds or WOT fuel burns and airspeeds.

Thanks
 
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