My Method - " The Gapless Hinge"

This is the first in a series of articles titled " My Method" in which I will supply an alternative method to a particular modeling dilemma. In this case , the "gapless" hinge.

First and foremost this is for use in a scratch built model, as this method is not applicable to an ARF (Almost Ready to Fly) or pre-cut kit without major modification.

The hinging of the control surfaces on a scratch built scale model is one of the most important decisions you will make in your project. During the construction of my Caudron, this decision was a tough one for me, as this plane is a racer and high speed was definitely in order. One of the most common problems in a race plane accident is control surface flutter. The gap between the control surface and the airfoil it is attached to is very critical to preventing flutter.

This picture shows the elevator of an electric ARF which was hinged with the mylar hinge (the one on the left in the picture below). It has a nice hinge line but you can see the gap and if not covered with transparent tape could produce control flutter.

This is a picture of the most common hinges and although they manufacture larger scale versions of these to fit my requirements, it occurred to me the biggest flaw in all of them is that they are installed into the trailing edge of the airfoil IN THE DIRECTION OF FLIGHT ! Now if the glue joint fails in flight, where is the control surface going ? I decided for this plane , there had to be a better way.

This diagram shows exactly how the gap can create instability. Figure 1 shows straight and level flight and the gap is not really an issue, but then when the control surface is deflected as in Figure 2 the amount of the airstream that goes through the gap is significant and must be avoided. Figure 3 shows My Hinge with zero possibility of airstream penetration.

My method is not difficult to perform but it must be planned for, because the key ingredient is the oversized trailing edge of the airfoil. This must be part of your initial design, because the trailing edge will be hollowed out to accept the control surface. Not only does this method eliminate the possibility of flutter, it also prevents glue joint failure of the hinge itself. Because the rod is installed from the end, this control surface will never separate from the airfoil. The pictures should explain the rest. Any questions, feel free to ask.

This is the stabilizer of my Bugatti, hollowed out to accept the control surface.

This is the control surface with the 4-40 rod inserted just behind the leading edge stock.

The first two holes are drilled with a drill bit and the rest are drilled by chucking the rod

in the drill and cutting the other end with some wire pliers which will leave an edge

that will easily drill through wood.

Here the rod is being inserted through the stabilizer tip then into the control surface,

then re-chucked in the drill to work it all the way through and drill the hole in the

other end of the stabilizer.

This is the finished result on my Caudron.

PilotOrNot.com

My Method - " The Gapless Hinge"

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