If you are tired of the same old boring food, then it’s time to get out the cookbook and spice things up! Here is a simple recipe to turn that boring old flat-bottom wing trainer plane into a hot new tow plane. Follow these simple steps to make your own homemade tow release mechanism and transform that old trainer into a delicious new dish that your entire club will enjoy. The following ingredients can commonly be found in most any R/C workshop.
Ingredients:
- Length of 2-56 size pushrod wire (about 6-8 inches)
- Length of 1/16” music wire (about 6-8 inches)
- Length of 1/8” O.D. nylon tubing (about 2 inches)
- Plywood plate (at least 1/2” thick)
- Thin CA glue
- Gorilla Glue
- Sandpaper (fine to medium grit)
- Servo (heavy duty servo with metal gears recommended)
- Servo connector of your choice
Tools:
- Small vise
- 1/4 x 20 bolt
- Hammer
- Pliers
- Wire cutters
- Drill
- 1/16” drill bit
- 5/64” drill bit
- 1/8” drill bit
Directions:
- Anchor the 1/4 x 20 bolt in the vise.
1/4 x 20 bolt fixed in vise
- Bend the 2-56 pushrod wire around the bolt to make a “U” shape.
bending 2-56 pushrod wire
- Use the pliers to squeeze the wire tight around the bolt.
adjusting with pliers
- Remove the bolt from the vise and insert the U-shaped piece. Allow the U to stick up out of the vise about 1/2 of an inch.
U fixed in vise
- Use the hammer to bend the “U” over making a 90 degree bend.
making the 90 degree bend
- Remove the wire from the vise and bend as needed for symmetry. Cut the “legs” of the U to about 1-1/4 inches in length and scuff them with the sandpaper.
fabrication is now complete
- Install the plywood plate in the top of the fuselage just aft of the wing. Mark the centerline of the fuselage on the plywood plate. Using the “U” as a guide, drill two 5/64” holes straddling the centerline and insert the U (but do not glue it in yet) allowing it to stick up about 1/4 of an inch.
test fitting all of the parts
- The U should have the open side facing toward the front of the plane. Drill a 1/16” hole down through the hardwood just inside the U. The 1/16” music wire pushrod will extend upward through this hole. Remove the U and enlarge the 1/16” hole you just made to 1/8” diameter. Insert the 1/8″ O.D. nylon tubing into this hole and glue it in using thin CA (we find that scuffing the nylon tube with sandpaper makes for a better CA bond). Once the CA cures, cut the nylon tubing flush with the outside surface.
Make sure the nylon tubing is cut flush
- Install your servo in the plane and adjust the servo linkage and/or travel so that the 1/16” music wire pushrod extends upward just slightly above the U to capture the towline and then retracts fully down below the surface so as to release the towline.
pushrod installation side view
- Remove the U and apply covering (if plane is not already covered). Scuff the “legs” of the U with sandpaper and reinstall the U with Gorilla Glue to anchor it in place.
Congratulations! You are now ready to tow your first Easy Glider.
completed release in the closed position
completed release in the open position
For larger tow planes, this same recipe can be used substituting 4-40 wire in place of the 2-56 size wire.
We used the 2-56 size wire to make the tow release mechanism for our Telemaster 40 tow plane, but we used 4-40 wire to make the tow release for our more powerful 2M Pilatus Porter tow plane. Both of these tow release mechanisms have proven themselves over many, many uses.
