REFLECTOR: Fuel Consumption Performance

[Scott Derrick]

Terry,

You probably already know this.

at that altitude you could run any mixture without fear of detonation,
however that is not how LOP operation is usually done.

For LOP you always lean to the last cylinder, not the first as you do
for ROP.

GAMI, recommends 75 LOP as the richest mixture now. Especially in a full
power climb.

nice numbers...

Scott

Terry Miles wrote:
> 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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>>
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