Ralf and Craig,

 

This is a story worth repeating a couple of times. My IV-P behaves exactly the same, as do all IV-series airplanes as far as I know.
Part of the cause is the rather small dihedral of the wings. When the airplane is not in coordinated flight, the yaw causes the fuel  in the wings to move sideways to find an “artificial level.” The inner fuel bays should be built with flapper valves to trap some fuel in the inner-most section of the fuel tanks during short periods of uncoordinated flight, but even that can be negated with extended time in an uncoordinated condition. If the flappers are not working properly, the time available for uncoordinated flight can be very short…especially as the fuel quantity goes down. For these reasons, I plan to take off and land on the right tank, and manage fuel so it is the fuller tank for landing as Craig explains.

 

Famous Lancair test pilot Don Goetz once told me after his personal experience with this during the first flight of a new IV-P: “I have added a new rule for flight testing your airplane. I want to see all the parts we sent you in the kit that you elected not to install.” …this after one of our builders decided that these flappers added unnecessary complexity…

 

But back to the point: Most LOBO members are on this LML and will have seen this, but we also have a lot of new, non-builder owners who may be learning these important lessons “the hard way.” I believe you when you say that getting an engine running after it quits during a go-around is “attention getting.” I also suspect that at least a few of our owners, no longer with us, failed in this attempt…

 

This would make an excellent article for our LOBO newsletter. Would you be willing to write it up as a “there I was” or similar format?

Thanks in advance,

Bob Pastusek

For LOBO

 

 

Ralf,

My experience is identical to yours and I have winglets.  When adding power and allowing the ball to move off center, a wing will drop and you get some lateral force in combination that unloads the left fuel port.  That is why I always land and take off on the right tank.  With Cheltons it is easy to check the trip planner once in cruise and know how much fuel you will land with.  I plan on having a few more gallons in the right tank and land on the right tank. I keep fuel balanced within 8 gallons or so and I never have to trim the ailerons.  If a wing is low, it is always due to rudder trim.  I do not have a yaw damper.  It is important to keep the ball centered on takeoff with full fuel to prevent losing fuel out the left vent.

Craig Berland

N7VG

 

Dear subscribers,

I noticed a phenomena on my 4P that I thought might be worth sharing to see if it is unique or may be others experienced something similar:

When my ball is significantly out of center over a longer period of time (>30 sec), my fuel selector is on left, and I have less than 15 gals in my left tank my engine will quit due to fuel starvation.

It happens mainly when I am practicing approaches: on the missed go around, when I am busy applying power, getting gears and flaps up, selecting my next way point in the GPS, changing my approach plates… if I am on the left tank with low fuel and I forget to retrim the rudder for the changed power setting my engine will shut down due to fuel starvation. My fuel indicator will then show zero for the left tank. Switching the tanks and applying high boost brings it back to life within seconds. After 30 seconds or so I can see the original amount of fuel again in the left tank. It is not a big deal anymore because I know how to fix it but it certainly caught my full attention the first time.

In climb with full fuel I can also notice that I am loosing fuel out of the left vent on the wing tip if I don’t keep my ball in the middle.

In straight and level flight I can run this tank dry with the exact amount of unusable fuel to which I calibrated my fuel indicator on the ground.

The only explanation that I have for this phenomena is that this uncoordinated flight situation must create some kind of vacuum on my wing tip around the vent port that sucks the fuel out towards the wing tip away from the fuselage. I have the regular wing tips and not the winglets.

Any input or advice is appreciated.

Ralf