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Freeze Frame is finally finished and ready to fly! This has been one of the largest projects I've done. It started several years ago with the idea of having boosters on a large rocket that blew off in flight. I thought the pictures could be very nice. Here is the rocket just prior to its first flight to show the overall size of the rocket. It stands about 11 feet tall, 6" in diameter, and weighs about 70 lbs without motors. It is my first attempt at using strap on boosters. The strap on boosters were later redesigned to use a minimum diameter 54 mm booster. The reduced weight but still had the same performance. It is next scheduled to fly in July 2008 at Northern Colorado Rocketry's monthly launch on an N2800 and two K700's. The projected altitude is over 11,000 feet.

The main motor is a 98 mm and each booster has a 54 mm motor mount. This is the original booster design. Later the boosters were redesigned to minimum diameter 54 mm boosters.

This photograph shows the main motor mount with the original design of the two strap on boosters. The thrust of the boosters is transferred to the rocket via an aluminum ring attached to the centering rings of the main rocket.

This close-up shows how the boosters attach to the rocket. The booster droppers are prepped on the booster then attached to the main body of the rocket and clamped. The upper piece of the aluminum ring is permanently attached to the rocket body and the lower piece moves to clamp the booster dropper.

The fins were built nearly identical to BDCR. Only the shaped changed slightly. I used honeycomb and carbon panel and glued rounded pieces of hardwood to the edge. Then I prepared to vacuum bag.

The honeycomb and carbon panel was covered on each side with 10 ounce carbon weave and 9.8 ounce fiberglass. They were vacuum bagged under heat and pressure while the epoxy was cured. The resulting fins are extremely strong but relatively lightweight.

I did attach the fins slightly different than BDCR. For Freeze Frame, the fins were attached after the motor mount was glued into the body tube. I still used a jig for alignment. The bungee cord was used as a clamp to hold the fins in tightly next to the motor mount.

I used a makeshift oven to elevate the temperature while the epoxy was curing. Elevating the temperature provides a higher Heat Deflection Temperature for the Epoxy.

I made a oven for curing the epoxy at elevated temperatures. It is made from Styrofoam and wood frame and lined with aluminum coated bubble wrap insulation. The heat is supplied by a portable space heater. It can reach temperatures of about 180 F.

Here is the initial test for dropping the boosters. Its a 3.3M video file. The sounds you here are the high speed cameras running.

This is a new way for me to mount the camera on board the rocket. In previous projects such as BDCR the cowling was built on the nose or body tube and the camera attached to the cowling. With Freeze Frame that camera is mounted to a plate that is attached to the payload section. The nose cone and cowling fit over the payload section and are screwed into place. The nose cone and cowling just act as the wind break for the camera and payload section.

This is also the first time for me to use the Milliken DB4 high speed camera. It doesn't have a magazine but it is capable of 400 frames per second. In addition it is capable of changing speeds while running. This allows greater flexibility for shooting the flight. I'll used the highest speed (400 fps) initially during motor burn but then change the speed to 128 frames per second for he remainder of the flight.

The nose cone and cowling were built from conventional methods used on previous rockets. After a hole was cut in the nose cone for the cowling a box was constructed from carbon composite panels. Blue foam was attached and shaped. Then the foam was sanded to make the design more aerodynamic.

Here is and end view showing the hole in the nose cone and the box that was constructed from carbon composite panels. Later the foam was sanded to make the design more aerodynamic.

The bag was pre-staged inside the nose cone and cotton placed inside. Multiple layers of carbon were used and some pins stuck through the carbon into the foam held the carbon from slipping while epoxy was applied.

This shot shows the multiple layers of carbon with different weave patterns and the stick pins going through the carbon into the foam to hold the carbon from slipping while epoxy was applied. A small amount of high strength filler was used in the epoxy.

Under vacuum I used rollers to push the excess epoxy to the edges. I used extra stretchy bagging material because of the highly complex shape.

After the vacuum bag was removed and the excess epoxy sanded off the results look good. Vacuum bagging compresses the carbon fabric tightly so there are no voids or air gaps to weaken the cowling. Its a lot of work but the result is stronger than just using the carbon and epoxy alone.

The carbon on the cowling was then coated with a layer of epoxy with sandable filler mixed. It is now ready for sanding.

This is a very large (10.5M) video of testing the ejection charge for deploying the drogue. Four 4-40 nylon screws are used for retention. The volume is very small so only a 0.5 gram charge was necessary to blow the two sections apart.

Also a very large video (over 11M) for deploying the main chute. The payload section also used four 4-40 nylon screws. This is why I don't like trusting calculations for ejection charges. The numbers show this rocket should use over a 3 gram charge. Here is the test of only 2 grams, do you think its sufficient?

The new booster design used minimum diameter boosters so the booster droppers had to be attached entirely to the outside of the booster tube. To accomplish this the booster droppers were drilled and tapped so a 3/16th inch piece of G10 fiberglass could be attached to it with four 4-40 screws. The design had to be able to transfer hundreds of pounds of thrust to the main rocket.

To attach the booster droppers to the booster, an alignment jig was used. This piece of aluminum was the same piece used to space the mounts on the rocket to ensure the booster mounts were the same spacing as the mounts on the rocket.

A template was made that would align and support the aluminum jig to hold the booster dropper. Later this same jig would be used to mount the fins onto the booster.

This is a close up shot of the forward booster mount for the booster dropper being glued on. The jig aligns the aluminum bar but does not actually support the weight. This set up aligns the booster droppers in all directions while the epoxy cures. High strength filler was used in the epoxy to increase strength.

After the epoxy cured and the alignment jig removed, the corners were sanded and more epoxy with high strength filler was added to the sides. This was probably not necessary and could have been accomplished with the last step for installing the booster droppers.

A cone was made from mylar that would be used as a mold for the final step to secure the booster droppers to the boosters. The size was calculated to make the cone be tangential to the booster body tube on the sides and maintained the same length for the ends. So the cone was "flattened" and the intersecting shape on the body tube is an oval.

The cone was taped in place and the epoxy with high strength filler was injected in with a syringe.

The result was a very smoother aerodynamic cone that was also very strong. Some more epoxy had to be added at the site of injection but the result was very nice. The lower mounts had some lead shot to adjust the balance of the booster.

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