lml@lancaironline.net Mailing List Archive

Bryan,

I've been using a dipstick all along getting good results, but I forgot to mention one thing - my tanks are of a different configuration than most or maybe all of the other ES's. My filler caps were already installed in the standard location, but I wanted an extra bay of fuel. I was a bit upset with Lancair (I think I was the first or second for the factory-assist wing closing), but we went ahead and extended the tanks. The result is that the filler port is one bay inboard from the end of the tank. The capacity is a bit less at 45 gallons per tank, but there is a few gallons of air space in the tank after filling. Advantage is that the vent is above the filler, allowing some expansion without venting fuel overboard. The second advantage is that the filler is closer to the center of the tank and that makes the dipstick give a more accurate reading. I have only 14 gallons before the dipstick reads any fuel - not a problem as I wouldn't likely take off with less than that in a tank anyway. A disadvantage is that the top 7 gallons don't register on the gages - they read 38 gallons until the fuel burns down to that level; again, not a bother. I think if I were building another ES I would do it the same way. 90 gallons is enough for me.

There were some that proposed carrying more than the required fuel increased the "stress and strain" on the airframe, but I don't buy that. The extra weight is quite far out in the wings and might actually reduce the total spar bending moment. And it would reduce the loading on things like engine mounts during turbulence as a given gust would produce fewer G's. The extra weight certainly requires that the engine be run at high power settings longer since the climb rate is lower and that would certainly reduce the engine life.

I must be in the minority, as in the last 30 years of flying I have seldom taken off with full tanks - just like the airlines :-)

Gary

To:
"" <lml@lancaironline.net>
I don't think the fuel level in a Lancair ES can be accurately determined using a dip stick. The fuel is mainly stored towards the wing root and away from the filler port. It doesn't take much flight time for the fuel to disappear from sight when looking into the filler port but there is still a significant amount remaining. Therefore, the sole source of fuel quantity is the gauge. Which leads me to top off before each flight. I then know exactly how much is onboard. The only true source of fuel information is starting with a known quantity and time. Gauges are a great backup until they go blank as can be the case with the electronic screen displays installed in so many of our airplanes.

Personally I always start topped off. Fly 30 minutes on the left (climb power) 1 hour on the right, 1 hour on the left, then back to 30 minute tank switches to a total of 4 flight hours. Then I am looking to land. By that time I am well over 800 miles, needing a rest, wanting to check my airplane mechanically, check in with business and family etc.

Good? Bad? or indifferent? That is my routine. I am used to it, it is the same every flight, it is proven as I have never run out of fuel, the time works for me, I can routinely verify my fuel flow rates, I usually am where I need to be well within 4 flight hours, the airplane handles the weight just fine, my climb rates are more than acceptable (900 fpm), TAS is more than acceptable at higher weight (210+ knots). Am I being inefficient? Probably. Am I putting additional stress on the airplane? Most Likely. Is it worrisome to me? No. The airplane was designed to be flown with the fuel capacity intended. And it is only at this capacity for a portion of the time as fuel is burned.

Bryan Burr
N132BB