REFLECTOR: Fuel Consumption Performance

Wed Aug 12 15:31:46 CDT 2009

I think the plugging should decrease with time. I bought my velo with 200 hours and no filter. The carb float valve was leaking, probably fouled by fiberglass particles. I replaced the float and seat and installed a cheapo NAPA in line filter. After 1 year/100 hours I replaced the filter. It had no pressure buildup compared to the new one. Over the years I have increased my run time. Last spring I replaced a filter after 3 years/300 hours and still no pressure buildup.

John

--- scott at tnstaafl.net wrote:

From: Scott Derrick <scott at tnstaafl.net>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Subject: Re: REFLECTOR: Fuel Consumption Performance
Date: Wed, 12 Aug 2009 07:08:34 -0600

Doug,

I'd like the details of that fuel filter incident? What kind of filter
you running? Was it a bad load of gas?

I used to have one of those little cylindrical filters you get at
autozone. glass tube with a replaceable white fabric(looked like
release) filter. About 2 inches long, maybe a 3/4 inch in diameter. I
always worried about that thing. replaced the filter twice a year.

Now I have a Fram canister filter that is 4inches in diameter, 4 inches
long, with a regular paper insert filter. Its 20 times heavier but can
hold a lot more gunk before clogging up.

Scott

Douglas Holub wrote:
> Got back from vacation today-- Texas to Seattle and back. My fuel
> filter clogged up at 10,500 feet between Butte and Missoula in the
> Rockies. Pretty exciting. Ask me about that story some time.
> Last two legs were Laramie, WY to Denver FTG, then FTG to Dallas. Had
> to divert around some thunderstorm activity, so those two legs were
> 765 nm on 38 gallons of fuel. 5.9 hrs on the hobbs. That's 20.1 nm/gal
> including two take offs and landings. Average TAS around 140-145 kts
> at 9500 feet, 2400 RPMs, 50 degrees LOP. IOX-360 with electronic
> ignition. FG with a retractable nose gear. Fixed pitch, 2-blade prop.
> Standard fuselage. Hauling about 475 lbs of people and baggage.
> Doug Holub
> N2980W, 95 hrs
>
> ----- Original Message -----
> *From:* Tom Tolton <mailto:tjtolton at charter.net>
> *To:* 'Velocity Aircraft Owners and Builders list'
> <mailto:reflector at tvbf.org>
> *Sent:* Thursday, August 06, 2009 8:08 AM
> *Subject:* Re: REFLECTOR: Fuel Consumption Performance
>
> Thank you all for the data on my fuel consumption question. I
> especially appreciate the time spent to help me better understand
> what is involved. It is a pleasure to be part of a group so
> interested in building and flying.
>
> *From:* reflector-bounces at tvbf.org
> <mailto:reflector-bounces at tvbf.org>
> [mailto:reflector-bounces at tvbf.org] *On Behalf Of *Al Gietzen
> *Sent:* Tuesday, August 04, 2009 12:15 PM
> *To:* 'Velocity Aircraft Owners and Builders list'
> *Subject:* Re: REFLECTOR: Fuel Consumption Performance
>
> Corrected data below - I made an error on the number for Dave’s
> plane; it should be 15.2 nm/g at 165KTAS. So you can delete the
> previous message and look at this one.
>
> Al
>
> -----Original Message-----
> *From:* reflector-bounces at tvbf.org
> [mailto:reflector-bounces at tvbf.org] *On Behalf Of *Al Gietzen
> *Sent:* Tuesday, August 04, 2009 7:54 AM
> *To:* 'Velocity Aircraft Owners and Builders list'
> *Subject:* Re: REFLECTOR: Fuel Consumption Performance
>
> Tom;
>
> Fuel burn is directly proportional to power produced; and speed
> increases by the cube root of power; so it’s very dependant on
> speed. But 6.2 gph at 125 is very good.
>
> Here’s a tabulation of what people have reported. Numbers given
> for fuel consumption are hard to compare because of different
> conditions, and degree of leaning, so everything below is
> approximate. Comparing at TAS helps as it eliminates some
> variables on air density.
>
> Just computing in nautical miles per gallon (nm/g)
>
> Jim - - - - - - - - - - - - 20.4 @ 143
>
> Tom’s friend - - - - - - 20.2 @ 125
>
> Terry - - - - - - - - - - 16.8 @ 193
>
> John - - - - - - - - - - - 15.5 @ 165
>
> Dave - - - - - - - - - - - 12.9 @ 185
>
> My SE RG with 20B rotary does roughly as follows: speed, burn, nm/g.
>
> 120
>
> 
>
> 6.2
>
> 
>
> 19.4
>
> 140
>
> 
>
> 7.3
>
> 
>
> 19.2
>
> 160
>
> 
>
> 9.0
>
> 
>
> 17.8
>
> 180
>
> 
>
> 11.4
>
> 
>
> 15.8
>
> In an effort to compare at the same speed, I assumed then
> relationship with speed would be about the same as my plane (using
> least squares fit to data). So translating to 165 KTAS, the nm/g
> comes out as follows:
>
> Terry - - - - - - - - - - 20.4
>
> Jim - - - - - - - - - - - - 18.8
>
> Tom’s friend - - - - - - 18.1
>
> Al - - - - - - - - - - - -- - 17.4
>
> John - - - - - - - - - - - 15.5
>
> Dave - - - - - - - - - - - 15.2
>
> Terry’s look very good (too good?); Dave’s are not leaned; and of
> course, the 173 FG with 200 hp could probably not go 165 KTAS.
>
> It is interesting to note that, for my plane, the nm/g flattens
> goes pretty flat as the speed goes below 140 KTAS, but does peak
> at about 130 – 135. So if you are looking for minimum cost per
> mile; somewhere about that speed may be it; but you’d have to run
> the numbers for your aircraft.
>
> Hopefully this doesn’t lose its formatting when transmitted.
>
> FWIW,
>
> Al
>
> -----Original Message-----
> *From:* reflector-bounces at tvbf.org
> [mailto:reflector-bounces at tvbf.org] *On Behalf Of *Tom Tolton
> *Sent:* Monday, August 03, 2009 3:29 PM
> *To:* reflector at tvbf.org
> *Subject:* REFLECTOR: Fuel Consumption Performance
>
> 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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