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Date: Tue, 10 Mar 2009 22:36:34 -0400
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From: David Standish <carbonflier@bresnan.net>
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Subject: Re: [LML] LOP vs ROP Climb: Time and Fuel Burn (LIVP)
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Thanks Jeff,

Next you might run ROP at the same performance numbers as you had LOP 
(152-157 KIAS and 600-900 fpm VSI) and see what the fuel burn is.  You 
probably will use a significantly lower MAP to get equivalent 
performance.  I bet 26-27" MAP.  That may significantly impact the 
difference you found in fuel economy.

David


Jeffrey Liegner, MD wrote:
> Here's some analysis on time to climb and fuel consumption in my LIVP 
> during a controlled ascent of 10,000' (from 6000' MSL to 16000' MSL) 
> in both Lean of Peak (LOP) and Rich of Peak (ROP) engine configuations.
>
> This test occurred over Pennsylvania 3/7/09, fixed heading (350*), 
> fully configured and stabilized in level flight (6000' MSL) at 34.8" 
> MAP and fuel flow, followed by a pitch up (over a known GPS reference 
> point) and climb (to 16000' MSL) either LOP (18.2 gph) or ROP (34.2 
> gph).  Winds were light out of the northwest (a quartering headwind), 
> remained consistent during both tests;  temps were above ISO.  The 
> test was conducted over a 32 min span of time.  Engine: TSIO-550E.
>
> _Lean of Peak (LOP) Data:_
> 10,000' climb at 34.8" MAP
> Fuel flow 18.3 gph (estimate 100*F LOP)
> Time Required: 11:28 min
> Distance Downrange: 30.9 nm
> Airspeed during climb: 152-157 KIAS (Calculated Groundspeed: 161)
> Indicated VSI: 600-900 fpm (Calculated: 870 fpm)
> Fuel Burn: 3.5 gallons (confirmed with totalizer)
> Highest CHT Temp: 360*F (CHT2)
>
>
>
> _Rich of Peak (ROP) Data:_
> 10,000' climb at 34.8" MAP
> Fuel flow 34.2 gph (Mixture full in)
> Time Required: 9:07 min
> Distance Downrange: 26.5 nm
> Airspeed during climb: 160 KIAS initially, but 165 KIAS last 1:30 min 
> due to CHT2 >410*F
> Indicated VSI: 1000-1400 fpm (Calculated: 1100 fpm)
> Fuel Burn: 5.2 gallons (confirmed with totalizer)
> Highest CHT Temp: 412*F (CHT2)
>
> _Bonus Data in Level Flight after ROP climb:_
> Immediate LOP to 18.3 gph
> Proceeded to 30.9 nm down range
> Additional time required in level flight: 1:17 min
> Additional fuel required in level flight (LOP): 0.4 gallons
> Total time to reach 30.9 nm down range: ROP 10:24 min (versus LOP 
> 11:28 min)
> Total fuel burn to reach 30.9 nm and 10,000' gain: ROP 5.6 gal (vs LOP 
> 3.5 gal)
>
> _My personal conclusion:_
> LOP during climb consumes 37% less fuel and only extends travel time 11%.
> CHT are much better LOP during the climb.
>
>
>
> Jeff Liegner
> LIVP in New Jersey