REFLECTOR: Performance

[steve korney]

Geoff...

This standard velocity would go 170 kts ground speed at 7500 to 8500 ft... It was built by Alan Shaw for a doctor in California a long time ago... Jon Bockman owns it now... Maybe he can chime in here... It has a IO 360 Lycoming with 10:1 pistons, two slick magnetos set at 25 degrees.  MT 3 bladed prop, no main gear doors...  Standard wing with under-wing cooling and air intake scoops... Weights about 1350 lbs...

Steve 

Date: Wed, 8 May 2013 11:35:05 -0400
From: peter.braswell at gmail.com
To: geoff.gerhardt at gmail.com; reflector at tvbf.org
Subject: Re: REFLECTOR: Performance

Hi Geoff,I'm still building, so I'm afraid I can't contribute much to helping you find more speed, but I was wondering what you're doing for engine cooling.  Do you have the newer style NACA ducts for engine cooling or do you have the older scoop?  I understand that can make a significant difference.

I was also wondering about the prop.  I opting for a V/P MT three blade hoping to be able to milk a little more top end.  Is your prop considered a climb, cruise or climb / cruise prop?

-Peter------------------------------------------------------------------------
"It's a Jungle Up There": www.zuluworks.com
------------------------------------------------------------------------


On Wed, May 8, 2013 at 10:38 AM, Geoff Gerhardt <geoff.gerhardt at gmail.com> wrote:

Folks,
I'm getting pretty consistent performance out of my 173RG over the last 8-9 months since initial flight testing.  My question to you guys is, are the performance numbers I'm seeing typical, or should I be seeing better performance?  Normally, on a cross country, I'll fly b/w ~8-12,000', ~60deg LOP which typically has me going 150kias at 8-8.5gph.  Full power, 160kias is about my max speed.  


I have a fixed-pitch Catto prop (66x74, design target 200mph @ 2800RPM).  When I'm doing 160kts, my prop is spinning at ~2800RPM.  That tells me that I have the power to spin the prop, but may have air frame drag that's keeping me from seeing the 200mph predicted by Catto at 2800RPM.


I have a standard 200hp, Lyc IO-360, Lightspeed EI on one side, Mag on the other.  Timing as per spec for both EI and Mag.  About 90hrs on the engine (rebuilt).  Compression/oil consumption is normal.  Very stable performance from the engine.


My plane is fully finished and pretty tight.  Main/nose gear doors are not hanging out and are reasonably well tucked in when the gear is raised.  Main wing angles of incidence are spot on, no rudder trimming was necessary to center the ball - she flies nice and straight.


The factory predicts I should be able to cruise at 175kias - that's just not possible with my current setup.  Can others with Std Velocities relate the performance you are seeing?  Is this as good as it gets, or does anyone have suggestions for things to check to see if I can eek out a bit more speed?


Thanks.
Geoff


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