1/16 balsa or basswood for fin stock
Estes PNC20 plastic nose cone (Viking nosecone)
9 of BT20 body tube
1/2 of 1/8 launch lug
engine block
12 inch parachute
18 inches of 1/8 elastic shock cord
clay for nose weight

Fin Dimensions:

Forward fins:

Span: 1.15 inches (29 mm)
Tip chord: 0.25 inch (6 mm)
Root Chord: 1.4 inches (36 mm)

Rear Fins

Span: 1.15 inches (29 mm)
Root Chord: 2.0 inches (51 mm)

According the simulation from Rocksim the best motors for the model are the B6-6 and C6-7 with ejection close to apogee. The first flight of the model was under relatively windy conditions, ~10 mph with a B6-6. The model boosted nice and straight, ejecting fairly close to apogee. The second flight (B6-6 again), on a nice calm day (minimal wind) also was nice and straight ejecting again close to apogee. The third flight was also on a calm day, this time with a C6-7. Deployment again was as predicted by Rocksim, near apogee. Fourth flight was on another windy day (10 mph) with another C6-7, resulting again in a nice straight boost despite the windy conditions. If built with the Cg in the correct location the model is quite stable, and gives an impressive flight. RockSim predicts an altitude of 830 ft on a B6-6 and 1390 ft on a C6-7.

1. Mark the body tube for 4 fins and a launch lug. Use the estes tube marking guide or the pattern from an Estes Viking kit to do this.

2. Cut out four each of each fin pattern from either basswood or balsa.
Glue on the fins as follows. The leading edge of the forward fin should be
2&1/2 inches from the front of the body tube. The rear fin set should be even with the end of the body tube.

3. Attach parachute and shock cord with an Estes style paper mount.

4. Glue in engine block so rear of a 18 mm motor protrudes 3/8 from the rear of the rocket.

5. After glue is dry, install a C6-7 motor and add clay to the nose until it balances just behind the forward fins (about 7&1/8 from the rear of the rocket). You will need to pack the nose cone just about completely full of clay.

To ensure stability of the model, you will need to add sufficient nose weight to balance the model just behind the forward fin set when a C6-7 motor is installed. I had to pack the nose cone completely full of clay to achieve this. For a recovery system a 12" parachute is recommended instead of a streamer as with the extra nose weight the model is relatively heavy for its size. If you wish, 1/16" basswoodmay be substituted for the balsa fin material.