Gyro Chaser

The Gyro Chaser is a highly efficient competition style rocket for the helicopter duration event for 18mm diameter rocket engines. It equalizes the playing field, giving even the novice competitor a great chance at winning first place.

What makes the Gyro Chaser unique is that it carries the rotor blades internally, inside the body tube of the rocket. While this means a little extra weight because of the larger diameter tube, the advantage is that the drag of the rocket is greatly reduced compared to externally mounted blades, like on our Heli-roc kit. It will fly a lot higher than your competitors' rockets.

Actually, with the Gyro Chaser, your rocket won't have much of a weight disadvantage, because it was designed to reduce weight as much as possible. The rotor head, to which the blades are mounted, weighs practically nothing - a mere 2 grams.

With its 18mm engine mount, this rocket is ideal for B and C size rocket engines. But watch out, and have your running shoes on; because it goes so high and hangs in the air so long, you'll be running a long way to chase this rocket. That's the downside of having a rocket that is so efficient.

Note: The YouTube videos for the Gyro Chaser Rocket were created in High-Definition format. Make sure to change the settings for Youtube to play in full screen mode, and in HD to see the small details in the video.

Step 1: Blade shaping by warping.

Step 2: Removing the blades from the dowel

Step 3: Assembly of the rotor hub

Step 4: Install the hub bearing tube

Step 5: Nose cone attachment

Step 6: Install the hub stop

Step 7: Engine Mount Assembly

Step 8: Glue the engine mount into the body tube

Step 9: Sanding the airfoil into the fins and sealing the balsa grain

Step 10: Glue the fins onto the body tube

Step 11: Attach the Kevlar^® shock cord to the joint where the fin meets the tube. - Note about the Kevlar shock cord: We shortened the length from what you see in the kit because we wanted to reduce the chance of the blades getting fouled (tangled) in the shock cord. Since it is such a lightweight nose and hub, it has very little inertia. That means the hub slows down very fast when it ejects out of the tube. It is like trying to throw a feather. Therefore, a short shock cord is just fine with this kit.

Step 12: Attach th for end of the Kevlar^® shock cord to the bottom of the rotor shaft

Step 13: Reinforce the slots on the rotor blades

Step 14: Glue the rotor blades onto the rotor hub

Step 15: Install the rubber bands that actuate the rotor blades. Balance the rotor assembly. Add a launch lug.

-- End of Videos

The Gyro Chaser was patterned after the FAI style helicopter rockets. Because the rules of international competition dictate that the rocket has to be 40mm in diameter, the rotor blades of those helicopter rockets have to be carried internally. The advantage of this is that it cuts down on aerodynamic drag, which means the rocket can zoom higher into the air. The Gyro Chaser is similar, but we used a smaller diameter tube to house the blades, which reduces the drag even more significantly. Our feeling was that if you aren't constrained by rules, then make it as sleek as possible. That is why it is based on 24mm diameter tubes. That size tube is a good compromise because it still has a large internal volume to hold the 8.75in long rotor blades, but it is still skinny enough to be lightweight and low drag.

The rocket features a central shaft that the rotor hub is attached to. We used the best material for this, which is graphite/epoxy. It is nearly unbreakable, and it is lightweight and perfectly straight.

The hub is designed to freely rotate around this graphite shaft. The advantage of this is that it limits the rotational drag of the spinning rocket, which could slow down the spinning of the blades. You want the blades to spin as fast as possible, as then they create the maximum amount of lift that slows the descent of the model. 

The other feature of those FAI style helicopters is that the rotor blades are curved. Instead of laying flat on a table, they have curvature to them, sort of like a potato chip.

The advantage of this is it creates twist in the blade that drives the rotation. Near the hub, the rotor blade has a very large negative angle of attack (see section A-A in the drawing to the left). Air flowing over this part of the blade will create a lift force that wants to pull the blade forward. This is what causes rotation of the rotor blades.

But at the tip, where the blade is thinner, the angle of attack is much less. And the lift force in this area counteracts gravity, keeping the rocket in the air for a long time.

The combination of blade twist and shape is what makes this style of helicopter so efficient. For more information about the theory on how this helicopter works, see Apogee's Peak-of-Flight Newsletter #342.

To be honest, as the designer, I'm very pleased about the rotor hub. But then, the design of this key component took over four months to perfect. Looking at its simple shape, it doesn't seem apparent at how complex it really is.

It does many different things:

1. The central hole allows it to free spin about the central shaft.
2. Provides three pivot point for the rotor blades.
3. The pivot points are exactly 120 degrees apart so your blades are spaced properly to provide easy balancing.
4. The pivot point is actually offset to the face of the hub, maximizing the strength of the dihedral stop which also allows for larger rotor blades.
5. The distance of the pivot points from the central shaft is set to maximize the width of the rotor blades.
6. The flat edges of the hub plate reduce any sliding friction of the hub as it ejects out of the body tube.
7. The radial slots in the hub plate prevent lateral movement of the rotor blades, so they are always perpendicular to the central shaft.
8. The support arms have a tooth on the tip that sets the correct dihedral angle of the rotor blades.
9. The support arms have a tab that engage a slot in the blades, so they are parallel to the axis of the rocket. It is impossible to have a crooked blade.
10. The support arm strengthens the balsa wood rotor blades at the point where they are their weakest.
11. The support arm also incorporates the hook for the actuator rubber bands.

The cool thing about this is that it is made out of laser-cut plywood, so the weight is reduced while the strength is increased. The hub is also very strong, and you'll break a blade long before the hub will break. And replacing a blade, as any experienced helicopter builder will tell you, is much easier than replacing a hub.

We rate this kit as moderately challenging (Skill Level 4 category) because it requires several construction techniques that you may not have done in your previous rocketry experience.

First, the blades are curved. They have to be warped into this shape by getting them wet in a solution of water and ammonia (we recommend Windex^® glass cleaner). If you try to bend them dry, they will easily crack; so they must be softened using the technique in the instructional videos.

Second, you will need a number of different types of glues (see the tools and materials listed below). This increases the difficulty, because each type of glue has its own characteristics. 

Third, you'll have to cut the little aluminum tubes with a hobby knife. This can be tricky, because the parts are small and can be easily ejected into the corner of the room where you'll never find them again.

Fourth, the parts of the hub are small. This will require a lot of dexterity in your fingers. If you have "all thumbs", you'll be cursing us for all the tiny pieces.

The good news is that all the wooden parts are pre-cut with extreme precision with a laser cutter. Everything fits just about as nice as you could wish.

The other thing that reduces the complexity of the model is that the instructions are in video format. Watching someone do these techniques seems to make it appear a lot easier. You will learn what is important (the intent), how to avoid making mistakes, and how to fix problems when they do arise. 

• 3/4-inch diameter dowel (at least 2 feet long)
• Pencil
• Ruler
• Scissors
• Hobby Knife - X-Acto with #11 Blade
• Ammonia-Water solution to curve the balsa (Windex^® window cleaner works well)
• Glues:
  • CA Glue (super glue) Water-thin viscosity (we recommend the applicator tip to go on the bottle)
  • CA Glue (super glue) Thick viscosity
  • Foam Safe CA Glue – Thick viscosity
  • CA Glue accelerator
  • Wood Glue
• Cloth strips (2-inch wide X 4 feet long)
• Sanding block
• Plastic bag
• Masking tape
• Permanent Marker (fine line tip)
• Aluminum Angle to draw lines on tubes
• Safety Glasses
• Finishing Supplies like sanding sealer, paint, and sandpaper (200 and 400 grit).

To Launch This Rocket Kit, You'll Also Need:

• Launch Pad & Controller - See below for recommended choices.
• Rocket Motors - See the motor selection table below.

• Pencil
• Ruler
• Scissors

• Hobby Knife - Hobby with #11 Blade

• Decal Tweezers

Random Selected Reviews:

William C. -- 02/17/2020

John Eric T. -- 03/15/2019

Trent N. -- 12/27/2021

Matthew D. -- 08/20/2022