Coldfire Nosecone

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Coldfire has a light weight plastic nosecone that contains a large payload bay compartment. The compartment is 3" in diameter and 14" long plus an additional space that extends another 10" but converges down to a point at the very tip of the nosecone. This payload bay will be used to carry a Walston radio transmitter and GPS telemetry system much like is done with the Angelfire nosecone.

The drawing at the lower left shows how the payload bay tubing is mounted inside the nosecone. This tubing slides in and out of the base of the nosecone and is secured by installing three small #4-40 machine screws into threaded holes in an aluminum retainer ring.

The aft end of the nosecone has a short piece of threaded rod that mates with a coupler nut on a bulkhead inside the forward end of the body tube. This allows the nosecone to be "screwed" onto the front of the rocket by inserting it into the forward end of the body tube and rotating it clockwise. It is just as easily "unscrewed" by rotating it counterclockwise to remove it.

The drawing at the lower right illustrates how all the parts fit together internally when the nosecone is fully mounted onto the rocket.

Click on either drawing below to get a better view.

The nosecone used for Coldfire is the "Pinnacle" nosecone from Giant Leap Rocketry. It is a white plastic 5:1 Ogive design with a nice long shoulder length on it.

The base of the nosecone had to be drilled with a 3" diameter hole saw in order to accommodate the payload bay tube.

This photo shows how the nosecone was mounted and held in place at the drill press. A piece of 1x12 pine was drilled with a suitable sized hole. The perimeter of the hole was lined with Duct Tape to prevent it from scratching the nosecone. The nosecone was then inserted into the hole and held in place with more Duct Tape.

The rear opening in the nosecone has been successfully drilled.

Aft end of the nosecone after drilling a 3" diameter hole.

This ring is sized to fit inside the bottom of the nosecone and to allow the payload bay tube to pass though it. It has two sets of three threaded holes. One set is vertical for mounting the ring to the nosecone and one set is horizontal for securing the payload bay tube to the ring. The ring is made of aluminum and was fabricated at a local machine shop.

Left to right we see the end of the payload bay tube, the aluminum retainer ring and the aft end of the plastic nosecone.

Retainer ring installed into the nosecone.

To install the ring, it was only necessary to gently squeeze the opening in the base of the nosecone into an oval shape and slip the ring inside. Three #4-40 socket head machine screws were then installed to secure the ring in place.

This was a test fit of the payload bay tube. It passes through the retainer ring and three #4-40 socket head machine screws are threaded through the tube and into the ring to hold the tube in place.

A plywood bulkhead (B5) with a threaded rod and coupler nut will be installed into the aft end of the payload bay tube. The exposed end of the threaded rod on the top side of the bulkhead will be used as a "hard mount" point for mounting the GPS telemetry system inside the payload bay.

Aft end of nosecone (with payload bay tube installed) along with bulkhead B5 (yet to be installed).

This photo shows how bulkhead B5 was epoxied inside the payload bay tube and about 1" from the end. The coupler nut has been covered with blue masking tape to protect it from epoxy accidentally getting into the threads. A one-inch strip of yellow Kevlar cloth was epoxied on to the inside surface of the tube to reinforce it. This Kevlar ensures that even in high G deployments, the mass of the nosecone and payload will not be able to tear the bulkhead out of the tube. The Kevlar also ensures that the screws that hold the tube to the retaining ring will not be able to tear through the tubing.

Assembly completed.

This shows the aft end of the nosecone with the short section of threaded rod sticking out that has a coupler nut installed. This coupler nut will mate onto a threaded rod inside the forward end of the body tube.