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  #1  
Old 12-15-2017, 10:23 PM
CAVU Mark CAVU Mark is offline
 
Join Date: Dec 2014
Location: San Diego, CA
Posts: 82
Default My 3 is too slow....

I bought a bit of a basket case and after a few months of work she is flying and I am learning to land.

It sports a O-320 with a Sterba 68 x 72 wood prop. Ed reconditioned it and the engine and prop were dynamically balanced.

So, what is the beef? I like to take it easy on the engine so I spin around 2300RPM and get 150MPH indicated. I think it should be more. Oh, and wheel pants are off while I learn to land her.

Sure could use some input.

Thanks.
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RV-3 restored - learning to land
Stearman - building - near 1st flight
L3 converting/building ribs
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  #2  
Old 12-15-2017, 10:53 PM
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Ironflight Ironflight is offline
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Wheel pants, gear leg fairings, and intersection fairings are worth at least 18 knots on an RV-6 if I recall correctly ( from tests we did about six years ago). I'd expect similar gains on a -3 ( plus or minus). Gear fairings are a big deal when it comes to speed!
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Last edited by Ironflight : 12-16-2017 at 01:22 PM.
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  #3  
Old 12-16-2017, 04:28 AM
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Larry DeCamp Larry DeCamp is offline
 
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Location: Clinton, Indiana
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Default 150 @ 2300

My IAS pretty much agrees with GPS on a calm day and these are the numbers I see on my 3B with about 1050 lb weight.
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  #4  
Old 12-16-2017, 08:00 AM
rmarshall234 rmarshall234 is offline
 
Join Date: Jun 2008
Location: San Diego, CA
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I would agree with Mr. Dye.

MY -3 was 826lbs empty and would true out at 198mph at 2400 rpm. It had molded fiberglass wing intersection fairings as well as the pressure recovery wheel pants and gear leg fairings. They make a huge difference.

Mine also had a Clark Lydick anhedral Performance Prop which I loved. I believe there is one for sale on this forum right now for a great price. If it matches the HP of your engine (and is the anhedral version) I would suggest buying yourself a Christmas present this year..
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  #5  
Old 12-16-2017, 10:00 AM
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Toobuilder Toobuilder is offline
 
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Is that 2300 RPM drag or throttle limited? If you're pulling it back to 2300 with the throttle, that's a large part of the issue. You should be able to turn 28-3000 RPM at full throttle at max cruise.

At any rate, 2300 isnt "taking it easy", its barely awake... Spin that prop!
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

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  #6  
Old 12-16-2017, 10:30 AM
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Larry DeCamp Larry DeCamp is offline
 
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Location: Clinton, Indiana
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Default Thanks Toolbuilder

Just for clarication, my numbers are throttle limited about 19 MP. I see about 175+IAS at 8,000 MGL and 2700 RPM.
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RV-3B flying w/ carb & Pmags
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  #7  
Old 12-16-2017, 10:20 PM
CAVU Mark CAVU Mark is offline
 
Join Date: Dec 2014
Location: San Diego, CA
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I am taking it easy at 2300 RPM since the engine is high time and I am watching it closely till my confidence builds. I will search for the prop, my plane is the 150hp version O-320, 770lbs.
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RV-3 restored - learning to land
Stearman - building - near 1st flight
L3 converting/building ribs
Helio Courier constructing
C-170A my trainer - sold
Kitchen - remodeling/done
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  #8  
Old 12-16-2017, 10:22 PM
CAVU Mark CAVU Mark is offline
 
Join Date: Dec 2014
Location: San Diego, CA
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Quote:
Originally Posted by Larry DeCamp View Post
Just for clarication, my numbers are throttle limited about 19 MP. I see about 175+IAS at 8,000 MGL and 2700 RPM.
I will give this a try next flight. I like going over the Anza Borrego desert at 10,500, peeking over the Laguna mountains all the way to Catalina. Cool, my 170 didn't do that and climb at 1000fpm. I now know the RV smile.
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RV-3 restored - learning to land
Stearman - building - near 1st flight
L3 converting/building ribs
Helio Courier constructing
C-170A my trainer - sold
Kitchen - remodeling/done
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  #9  
Old 12-20-2017, 01:09 PM
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dacronwall dacronwall is offline
 
Join Date: Oct 2013
Location: Palo Alto,CA
Posts: 89
Default RV-3 speed too slow

I agree with what many have said here...yes, I noticed a big difference when I had leg fairings and wheel pants off.
You have a pretty light -3 there at under #800 lbs, it should be fine with 150 HP, but the prop is a biggie. I would give Craig Catto a call if you are considering a new prop. I had him build me a custom carbon fiber prop that pulls like crazy. I flew out there and bolted on a test prop and took it up and flew a square course at 7,000 ft and took avg speed and RPM notes, then did climb performance test and he build my prop based on that.

N66GB
842 empty
160 HP IO-320
Custom Catto prop
Custom cowl (like a James cowl)
Custom wheel pants

I usually cruise around 180 mph at 2350 rpm. If I put the juice to it, it spins up to about 2,800 to 2,850 rpm (at 5,000 ft) and I have seen indicated speeds over 225 mph. I had her up to 228 at one point straight and level but I was too focused on not blowing up or crashing to record any real numbers or cross check with solid GPS data...
Hoping to fly her in sport class at Reno in 2019...testing continues.

Put in a little effort, and you will get more speed out of it...no doubt.
Good luck
Dave
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  #10  
Old 12-20-2017, 01:54 PM
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Toobuilder Toobuilder is offline
 
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Location: Mojave
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Interesting perspectives here. Recent post on the Biplane forum had the OP looking for a new prop because he was "only" running 3100 RPM. One of the other posters came on and asked why he didn't run "full" throttle?

Don't ever post over there and talk about "babying" an engine... Those guys run 3200+ and would laugh you right off the forum.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI instalation in work
RV-8 - Flying
1940 Taylorcraft BL-65 -flying
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