REFLECTOR:One Fast Velocity

Jim Sower reflector@tvbf.org
Sat, 05 Jun 2004 20:15:58 -0400


I have a std. FG with no wheel pants (yet), an IO-360 with Catto 
3-blade.  I like 10k' but usually end up at 8k +- 500 on cross country.  
I make about 150 KTAS at WOT, 2650-2700 rpm leaned juuuust LOP at 8.0 - 
8.2 gph.  How come my fuel burn is so much lower??


Scott Derrick wrote:

> I routinely cruise around 10,000ft, 2700 RPM,  9.5 GPH at 170-175 
> KTAS(depends on temp)
>
> Std-RG, IO360 with a fixed pitch Catto prop.  If I had an adjustable I 
> could go faster at a higher burn.
>
> Scott
>
> At 09:25 PM 6/1/2004, you wrote:
>
>> On Monday I went up with my friend Mike Deeter to collect some flight
>> performance data.
>> I must say that the Franklin and IVO prop make a screaming 
>> combination for
>> not a lot of $$$.
>> Its a standard elite RG.  Carbureted/magneto Franklin, electric IVO.
>> Nothing special.
>>
>> I wanted to get more data, but clouds below 5000 was a problem.
>>
>> The best speed we saw was at 7500 feet altitude, full throttle, the 
>> first
>> altitude where we actually
>> achieved full open throttle.
>> 182KTS TAS, 2520 RPM, 23.1 inches MAP, 12.4GPH.
>>
>> I was more impressed however, with putting more pitch in the prop.  
>> At this
>> same altitude, I took data at progressively slower RPM's (same 
>> throttle).
>> 174KTS TAS, 2300 RPM, 23.5 inches MAP, 10.8GPH.
>>
>> We stabilized a climb through 8000 feet at 120 kts indicated, 144kts 
>> true at
>> 700FPM rate.
>>
>> Levelling at 9000, going through various MAP/RPM settings, I was 
>> impressed
>> by the economies achieved:
>>         KTS TAS RPM     MAP     GPH
>> 1       147             2370    19.7    9.5
>> 2       180             2520    21.8    12
>> 3       175             2400    21.9    11.2
>> 4       162             2200    22.1    9.9
>>
>> At line 1, this is at 120 kts indicated (where I started data 
>> collection),
>> 147TAS.  This is partial throttle operation.  Not bad for 9.5GPH, but 
>> look
>> at line 4, full throttle, slower RPM.  Faster speed, with just a 
>> little more
>> fuel flow.  I find it surprising that pumping losses account for a 5%
>> penalty between lines 1 and 4.  That's 15.5 nautical miles/gal and 16.4
>> nautical miles/gal for lines 1 and 4.
>>
>> The most economical was at 7500 feet:
>> 174KTS TAS      2300RPM 23.5MAP 10.8GPH, making that 16.1 nm/gallon.  
>> I don't
>> know why I didn't get at data point at 2200RPM.  It would have been 
>> better
>> yet.
>> What this says to me is pick a MAP/RPM combo that is the economy 
>> setting you
>> want, then fly the altitude that will give you that power setting at 
>> WOT.
>>
>> It was hot too.  95F on the ground, adding about 3000' for density 
>> altitude.
>> I love this stuff.  Can't wait to go back up and get more data to 
>> fill out
>> the chart.
>> This data makes flying a Warrior look expensive.
>>
>>  Brian Michalk  <http://www.michalk.com>
>> Life is what you make of it ... never wish you had done something.
>> Aviator, experimental aircraft builder, motorcyclist, SCUBA diver
>> musician, home-brewer, entrepreneur and barely single
>>
>>
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>
>
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>
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