To ensure a strong rocket, we need to add fillets to the fins where they meet the Quantum tub on the inside and where the fins meet the Motor Mount.

First we removed the Aft Ring (pulling on the cellophane tags). This reveals the inside as shown below.

We then created a small batch of 5-minute Areldite and started to create a fillets. (3 x 4 = 12 fillets) in total. We used some doweling to get the Areldite all the way from the front end to the back. It was a messy job and it was hard to stop getting glue everywhere, but we tried hard. We made a special effort to stop any glue getting inside the motor mount and if any glue got on the outside of the motor mount (at the back end), we quickly wiped it off with a rag. We did this because we need to be able to insert the motor and we need to be able to put on the motor retainer.

Once this was complete, we then needed to put the AFT Motor Ring back into the quantum tubing with sufficient amount of Areldite to ensure it would not come out.

What can we learn from this?

While the external fillets created are strong and will definitely hold the fins in place, because there is no camber (concave surface), we have an abrupt change in surface direction and this will invite turbulent flow and so drag. This probably won’t be detrimental to the flight, but the maximum altitude won’t be attained. Something to be mindful of in L2 and other future rocket builds.

The rocket motor doesn’t get attached directly to the Callisto’s Quantum Tube. The motor is inserted into the motor mount tube. This ‘motor mount’ (a cardboard tube) is secured inside the Quantum Tubing with some circular rings that are glued. These rings themselves are also glued to the motor mount tube and we have the Piston strap (A strong thick black cord) securely glued to the motor mount. Some pictures of the construction of this component are shown below:-

We created fillets around the motor mount ring to ensure it will not budge during flight or ejection.

We took care here to ensure we did not clog up the slot. We insert the piston strap into this slot later on and Areldite it in place.

After the Piston Strap glue had tried, we packed it inside the motor mount to keep it out of the way in the next lot of steps.

Next step was to start gluing the Motor Mount to the rocket tube. We put some Areldite ~7inches into the back of the rocket (in a ring) using some long doweling. We then pushed the Motor Mount all the way in, till the appropriate amount was sticking out. (We are using HAMR motor mount, so we need to leave sufficient amount of space to attach Retainer on to the motor mount). We had to leave the rocket in a vertical position to allow the glue to flow down and remain against the motor mount top ring.

I started bulding the rocket up by first making a jig to keep the fins orientated 120degrees apart. I decided this was critical for a successful flight and so did this immediately. Some pictures are shown below of this.

I had to sand the cuts in the plywood with sandpaper to widen the gap to allow the Fibreglass fins to snuggly slide in them.

It is easier to scuff the fins, so that the primer sticks easily to the fins before they are attached to the rocket tube. So we do that now. See pictures below of this.

I carefully chose a rocket to gain my L1 certification. I wanted to get a rocket that I could also use with smaller rocket motors (which means I can legally fly it). Once I have my L1, I can then legally fly it using  larger rocket motors. The rocket I choose is a Callisto which I got from http://ausrocketry.com.

Below are some pictures of the parts carefully extracted from the delivery box and spread out for each viewing and inspection.

There were a lot of additional items required to build the rocket:-

• 5 Minute Areldite
• A scalpel
• Paddle pop sticks
• Sellys Epoxy Putty
• 120, 240, and 400 grit sandpaper
• Masking Tape
• Dowling
• Block of Wood (for mixing Areldite on)
• Sticky tape
• Pencil
• Black Marker
• Ruler
• A large clean workspace with good light