Modifying a Sky Streak (Rubber-Powered Balsa Plane) for Better Performance

The Sky Streak is a balsa motorplane that can be easily assembled by just about anyone and can be flown either indoors or outside. It is a free flight aircraft, meaning that once it is launched it flies without any direct control until it lands and you retrieve it. One of the fun things about this particular motorplane is that it is powered using a rubber motor and propeller to help it fly farther and longer than a traditional unpowered motorplane.

Sky Streaks are great to build and fly for fun at home or as part of a classroom or informal education activity. They are used very successfully at the National Model Aviation Museum to harness the power of flight into an engaging hands-on experience. You can order individual Sky Streaks at the AMA online store.

Or purchase a classroom set of 25 at a great discount from AC Supply. It is always a good idea to have a few extra kits in case of broken pieces.

Although the stock Sky Streak flies well, there are some special modifications you can make to really enhance flight performance. You may need to purchase some of these supplies from your local hobby shop or hardware store, or you can order them online.

Supplies Needed

  • Armor All or rubber lubricant (optional)
  • Ballpoint pen
  • Building board or workspace covered with newspaper, if necessary. This can be the edge of a table, a piece of plywood, the side of a clipboard, or any other material that would serve as a sturdy straightedge.
  • CA accelerator/kicker
  • Cyanoacrylate (CA) adhesive
  • 1/8th inch rubber motor material (included if you purchase your kit at one of the links above)
  • Scissors
  • Sky Streak kit

Forming the Wings into a Polyhedral Shape

Altering the shape of the wings will increase the stability of the Skystreak as it flies through the air. We will create a polyhedral shape by bending the  wingtips up. Here’s how to do it:

  1. First, unpack all of the pieces from the kit and set them out.
  2. Use the pilot/rudder/stabilizer assembly piece to measure from the very edge of one of the wing tips.
  3. Gently score a line using a ball point pen.

  1. Repeat this on the other wing.
  2. Insert the wing into the fuselage (main body of the airplane) with the printed side facing up.

  1. Clear building board (if using one) and stand on its side in front of you. Place model behind the building board with the printed side facing you. Align the edge of the building board with the scored line on the wing tip. Place palm behind the wing tip and gently pull it towards you, placing a crease in the wing tip. Repeat this step for the other wing tip. If you aren’t using a building board, you can use the edge of the table to crease the wingtips.

  1. Remove the rudder from the assembly piece. Align the rudder under the wing tip, as pictured, with the long side facing down and the rounded edge facing away from the wing. This should place the wingtip at roughly a 45 degree angle.

  1. Carefully run a line of CA along the scored line on the wing tip while it is held at that angle and spray with accelerator/kicker to help the glue set quickly. Repeat this step for the other wing tip.

Modifying the Rudder

  1. Remove stabilizer from the assembly piece and insert it into the rear, bottom slot of fuselage.
  2. Place rudder into the slot above the stabilizer with the pointed tip facing up and the rounded edge facing away from model. Cut the tip of the rudder off with scissors.

Modifying the Rubber Motor

  1. If your Sky Streak kit came with a blue rubber motor (it looks like a large rubber band), put it aside. This stock motor has very limited performance. If you ordered your Sky Streak from one of the providers above, it should have come with an additional strip of tan rubber. This is called “competition rubber” because it will yield much higher performance than the blue motor.
  2. You may need to tie the competition rubber motor so it makes one large loop, if it came as just a strip of rubber. The finished motor should measure about the same length as the fuselage.
  3. You can use Armor All or other rubber lubricant to increase the performance of your rubber motor by decreasing friction. Place the rubber motor in a small plastic bag and spray some of the lubricant into the bag to coat the motor.
  4. Push the plastic propeller onto the front of the fuselage with the hook facing down.

  1. Hook the rubber motor onto the propeller hook with the knotted end towards the rear of the fuselage. Hook the knotted end on the rear fuselage hook.

That’s it! You’re ready to fly!

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