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dave.saylor.aircrafters(a
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 Posted: Sun Jun 30, 2013 2:10 pm Post subject: Fuel Question |
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A little background: we just finished the Hayward Air Rally (www.hwdairrally.org) for about the 10th time. We placed 8th out of 22, which is about where we usually place.
The rally judges us on fuel and time estimates during routes from the Hayward, CA to Redding, then to Bend, OR. We were 1.2 gallons off of our fuel estimate and 37 seconds off our time estimate. The winner was 6 seconds and 0.3 gallons off his estimate, in a 172.
This year we tried the "Glass Class", which allows us to us to use all available technology, instead of just a compass, map, and stopwatch. The penalties are tripled and our score ended up similar to our past entries. The winner was in traditional class.
Every year the fuel penalty is our nemesis. We know why our time was off, and next year we'll adjust for that. But we can't nail the fuel for any amount of trying, even using the totalizer.
There seem to be two issues. First, the totalizer doesn't seem to be as accurate at low ie, idle, power settings. It generally reads 2-3 gph, which we think is high.
Second is refilling the tanks to the same level each time. We can't top the tanks or it will vent enough overboard to ruin our score. We use tabs that I installed to fill the tanks to about 28.5 gallons. Even refilling to the same spot on the tab doesn't really return the results we want. We need a system that will show when a tank is refilled to just the same level each time.
Any suggestions? The rules allow us to level the plane, which we started doing this year, and we can use a stick so long as it only has a single calibration mark. We haven't used a stick yet. I'm also interested in what others have noticed as far as extreme accuracy of their totalizer. Plenty of folks report sub-gallon accuracy. Anyone doing much better than that? How?
Last thing, the rally will be going from Hayward, California to Oshkosh for AirVenture next year. It's a lot of fun, even if somewhat frustrating, and of course a great challenge. If anyone is interested, please look into it. More RVs would be great!
Dave Saylor
[url=tel:831-750-0284]831-750-0284[/url] CL
[quote][b]
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woxofswa
Joined: 12 Aug 2008
Posts: 349
Location: AZ
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| Posted: Sun Jun 30, 2013 7:42 pm Post subject: Re: Fuel Question |
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It is surprising how much temperature plays a role in the volumetric measurement of fuel.
For extreme accuracy, you would need a temperature adjustment formula or graph to fine tune a dipstick measurement. Airliners use dripsticks underneath the wings but the reference tables are graphed by different temperature ranges.
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Myron Nelson
Mesa, AZ
Flew May 10 2014 |
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Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
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| Posted: Sun Jun 30, 2013 7:45 pm Post subject: Re: Fuel Question |
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37 seconds? That could just be the tower sequencing you #2 instead of #1. How can you plan for that?
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Bob Turner
RV-10 QB |
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dave.saylor.aircrafters(a
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| Posted: Mon Jul 01, 2013 6:11 am Post subject: Fuel Question |
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These days we're all assigned GPS loggers. Ideally, the flagger gives us the "GO" sign at the top of the minute but even if they don't, the data shows pretty clearly when we start moving within a second or so. We get a dedicated runway (usually) so we can take our time for the start. ATC isn't involved, and it's the total flight time we're concerned with, not the UTC start and stop--thankfully.
The end time is a low pass over an airport near the end point.
Dave Saylor
831-750-0284 CL
On Sun, Jun 30, 2013 at 8:45 PM, Bob Turner <bobturner(at)alum.rpi.edu (bobturner(at)alum.rpi.edu)> wrote:
[quote] --> RV10-List message posted by: "Bob Turner" <bobturner(at)alum.rpi.edu (bobturner(at)alum.rpi.edu)>
37 seconds? That could just be the tower sequencing you #2 instead of #1. How can you plan for that?
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=403671#403671
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dave.saylor.aircrafters(a
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| Posted: Mon Jul 01, 2013 6:19 am Post subject: Fuel Question |
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Yep, temp is huge, especially when we used to vent half a gallon overboard before we even started! The planes are topped and impounded the night before departure, so the fuel gets to warm up all afternoon. I think we've handled that but I wouldn't be surprised if the fuel flow is also affected.
But it's not impossible, and it's not dumb luck...I just don't know how it's done yet.
Dave Saylor
831-750-0284 CL
On Sun, Jun 30, 2013 at 8:42 PM, woxofswa <woxof(at)aol.com (woxof(at)aol.com)> wrote:
[quote] --> RV10-List message posted by: "woxofswa" <woxof(at)aol.com (woxof(at)aol.com)>
It is surprising how much temperature plays a role in the volumetric measurement of fuel.
For extreme accuracy, you would need a temperature adjustment formula or graph to fine tune a dipstick measurement. Airliners use dripsticks underneath the wings but the reference tables are graphed by different temperature ranges.
--------
Myron Nelson
Mesa, AZ
Emp completed, QB wings completed, legacy build fuse on gear. Finishing kit and FWF kit in progress.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=403670#403670
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" target="_blank">http://www.matronics.com/Navigator?RV10-List
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MS -
k">http://forums.matronics.com
===========
e -
-Matt Dralle, List Admin.
t="_blank">http://www.matronics.com/contribution
===========
[b]
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