REFLECTOR: Performance

Laurence Coen lwcoen at hotmail.com
Wed May 8 11:27:30 CDT 2013


Geoff,

160 kias at 10,000 feet DA is 186 ktas or about 214 MPH.  175 kias at sea level on a standard day is actually slower.  Even 150 kias at the 10,000 ft altitude is 174 ktas and still over 200 MPH.  You're doing great.

Larry Coen
N136LC


From: Geoff Gerhardt 
Sent: Wednesday, May 08, 2013 9:38 AM
To: Velocity Aircraft Owners and Builders list 
Subject: REFLECTOR: Performance


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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