RIGGING YOUR DT LINE

 

One of the most common questions we see is how to rig the stabilizer for the remote DT line from our timers. Larry Davidson of Moneta, VA is a very successful competition flier and a good customer. He has generously provided a set of photos that details how he does it. The plane in the example is an ignition powered Alert with our Ultimate OT timer. However, the methods and techniques shown are applicable to any of our timers with a DT function, and most planes, regardless of size or power. Obviously, there are changes one can make to suit individual preferences and particular aircraft.

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OVERVIEW

Larry uses 50 pound test DacronŽ fish line for his DT. (20 pound line for .20 and under planes) He uses a DT limit stop on the fuselage to stop the line after release so the correct stabilizer angle (about 40-45 degrees - refer to your plans) is achieved. He makes a 90 degree bend in 3/32" OD aluminum tubing (from K&S) to convert the line running parallel to the fuselage to to one going up through the trailing edge of the stab. NOTE: in these photos the aluminum tubing is outside the fuselage. Some will prefer to have it inside. The choice is yours, but keep in mind how you will replace the line when needed. Rather than a rubber band for line tension, Larry uses a coil spring that he makes himself from 0.020 music wire. To minimize the shock when the spring hits the limit stop, Larry slides a piece of silicone tubing on the line between the spring and limit stop. The "T" used on the stab end to hold the TE down is slid through the hole in the stab during preparation of the model for flight. The photos should answer any questions you have.

To see how the DT line is attached to the timer post, click here.

 

 This shows the stab in the held down position. Tension is on the line going to the timer. The keys to hold the stab in alignment when down is just visible on the bottom.

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This is a drawing of the hold down wire that is firmly attached to the stab TE. In this case Larry trapped the wire under the rudder and then used epoxy. A rudder to trap it will not be present on all planes, so use of a plywood "sandwich" with epoxy might be called for. You might also have the line inside the fuselage and come up directly under the TE. Then, you would use a piece of  ply to give a hard surface for the ":T" to sit on. In any event, make it strong (but light)!

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This shows the  3/32" OD aluminum tubing used to feed and guide the line to the stab TE. He uses a square knot to tie the line, with a drop of CyA to lock it. 

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This shows the stab in the up or DT position. The travel is limited by the line stop on the fuselage. If one does not want to use a line stop, then a separate limit line would need to be used at the tail. NOTE: some plane designs have a "built-in" limit on the stab travel, so no other limit is needed.

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This shows the limit stop attached to the fuselage just to the right of the timer. The spring is self-made. from .020 music wire. The silicone tubing is used as shock absorber.  (The material used is actually the fuel line we sell.)

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