Wednesday, August 19, 2009

159 Sailplane Today's Progress on the Final Assembly

Report #159 from Tandy Walker on the construction of his Comet Sailplane for the 2009 SAM Champs in Las Vegas

Comet Sailplane Project
The picture below shows the integrated ignition unit consisting of (1) a 750 mAH NiMH battery pack, (2) a ModelElectric coil, and (3) Marv Stern's Aero Tech IGN-SW ignition module installed on the back side of the Sailplane's firewall with two 2-56 cap screws. You can see the (+) ignition pack charge terminal and the (+) booster terminal wires with lugs soldered to their ends. In addition, the landing gear has also been installed.

With the two wire lugs attached to the terminals on the back side of the hatch cover, this picture shows the two external terminals and the hook up for charging the ignition pack and attaching external booster batteries (note that the landing gear wire is grounded to the engine).
The green wire in the picture below is the landing gear's ground wire to the engine for the booster and ignition pack charge grounds on the landing gear shown above. I was doing a continuity check with the multimeter that you see in the picture.

This picture shows the ignition unit's ground and point wires. Notice that the high tension lead is too short to be routed up through the cowl and to the spark plug.

So I started making a new high tension lead. Larry Davidson sells the clip shown below that snaps onto the coil post. Years ago Dick Huang gave me bunch of very small aluminum brads that I use to attach the high tension wire to the coil clip. About a 1/4" of the insulation on the high tension wire is removed and the stranded wire is bent through the hole in the coil clip. The aluminum brad is also pushed through the hole and then flared out, which attaches the high tension wire to the coil clip. Black heat shrink tubing is used insulate the connection as shown below.

James Lollar is sending me some 1K and 10K resistors to use inline with the little spark plug clip that I make, but they have not arrived yet. I will probably use a 10K resistor and locate it as close to the spark plug as practical. Well, that it for today.........................Tandy

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