REFLECTOR: Fuel Consumption Performance

Terry Miles terrence_miles at hotmail.com
Mon Aug 3 21:00:10 CDT 2009


Tom,
I've got an XLRG-5 IO-540K 300 HP with a 3-blade constant speed ACI prop.
These numbers are about 2 weeks old.  Same day taken only an hour or so
apart on the xc from PA to IN.    

Altitude  10000       12000
OAT C	    +16		+12
TAS       193		195
IAS       160		157
FF        11.5		11.5
RPM       2330		2390
% pwr      64  		62           wide open throttle
Oil T      192
Oil P       66
Cyl ave    300          25 hotter
EGT        1230         same

I lean until my first cyl is 50 lop and quit there.  I can likely go to 11
gal.  
I was about 2600 gross wgt at the time.    

Terry Miles

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Tom Tolton
Sent: Monday, August 03, 2009 19:39
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: Fuel Consumption Performance

Thanks Brian.  I'll start looking for BSFC numbers. After posting my last
message I found an article where a LANCAIR with a 550N was tested to
determine the Vbc or velocity for best CAFÉ or best Comparative Aircraft
Flight Efficiency.  At 12.5 K density altitude 2300 rpm and 248.3 smph they
were able to reduce fuel consumption to 10.4 gph LOP.  Do you know if
Velocity has entered the CAFÉ competition?  

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Brian Michalk
Sent: Monday, August 03, 2009 8:16 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Fuel Consumption Performance

You want the BSFC number.  Brake Specific Fuel Consumption.  The smaller the
number, the better.

Typically, the following lower the BSFC:
large displacement
high compression ratio
low RPM

Tom Tolton wrote:
> I recently traveled to Oshkosh with a friend who owns a Velocity 173 
> with fixed gear and a 200 HP fuel injected Lycoming.  He was able to 
> reduce gas consumption to 6.2 gallons per hour at 10500 feet and 
> maintain a speed of about 125 nm/hr using LOP techniques.
> 
>  
> 
> I am building a XLFG -5 with constant speed propeller.  I am looking 
> for what one might expect in minimum gas consumption using LOP 
> techniques at a density altitude of 10000  feet.  I am considering the 
> Lycoming IO540 260 and 300 HP, as well as, the 310 HP Continental 
> 550N.  It has been suggested that if I buy one of the more powerful 
> 300 HP engines  I will just be able to run with less throttle and 
> bring the fuel consumption to a reasonable level.
> 
>  
> 
> I would appreciate any comments / experience of the builders and owners
> with a similar XLFG configuration.    
> 
>  
> 
>  
> 
>  
> 
> Tom Tolton
> 
> 989-835-5828 (Home)
> 
> 989-750-8567 (Cell)
> 
>  
> 
> 
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