Thursday, June 27, 2019

Returning a veteran to duty...

In 1972, Cox (which was then a separate company from Estes) offered a line of all-plastic ready-to-fly model rockets, many of which were scale models. My rocket builds looked like crap back then, so I was all about good looking birds that I could fly immediately after taking them out of the box. Thus I acquired my first Cox model rocket, the red and white Honest John. It was not a member of my fleet very long, borne away by the wind after being lofted to altitude on a C6-5 (My fleet was very small in Jr. High - I was in the "stick the biggest motor you can into it" phase, which meant most of my rockets sailed away well beyond the bounds of our small neighborhood flying field). A few years later I bought a Cox 1/125th scale Saturn 1B, which made several flights on dual C6-3's. Being all plastic, it was rather heavy, at about 6 ounces. One did not dare attempt to fly it on a single 18 mm Estes or Centuri motor - they simply did not have the power to loft the Saturn.

The Cox Saturn 1B, released in 1972 (Click to enlarge).
Flash forward to 1989... I had been introduced to composites at NARAM 30 the year before, and I was eager to try some of these motors out. The Saturn 1B had miraculously managed to hang in there with me, and I thought that it might be the perfect vehicle to try out one of the 18 mm Aerotech E25's (I had considered sticking one in an Alpha, but figured it would be an embarrassing shredsville). So I gathered together my compadres and we trekked out to a field just outside Gainesville, Florida for my momentous entry into the world of composite rocketry. The Saturn was placed on the pad, the count given, and the launch button pressed.

It took off like a bat out of Hades, riding a pillar of white fire, accompanied by a very satisfying roar.

There was much applause - until the shock cord broke.

The large bottom part of the rocket descended safely under the parachute, but the upper piece (LEM shroud, service and command module, and LES) tumbled to the ground. Naturally, the escape tower broke off on impact. "No problem" I thought - "I'll just glue the escape tower back on." However, an inspection of the lower part of the Saturn showed that it too had suffered damage - but not from hitting the ground. The heat of the Aerotech motor had melted one side of the model, and a piece of the upper bulkhead was missing, blown away by the ejection charge. The interior looked like I had dumped a bag of soot into it. Apparently, the Aerotech motor was too much for the rocket, in a lot of ways.

I still have an old Aerotech E25, similar to the one that scorched/melted my Saturn.
Don't know what to do with it, but it has to be something special (Click to enlarge).
And so I consigned my injured Saturn 1B to the box of misfit rockets, where it has lain for 30 years.

The Apollo 11 50th anniversary is next month, and, like many of my kind, I have purchased a 1/200th scale  ready-to-fly Saturn V from Estes. It has a couple of things in common with the Cox Saturn 1B - 1) it's all plastic, and 2) it's a pig, weighing 4.5 ounces without motor. Estes recommends only a C6-3, but the weight of this rocket is well above the maximum lift-off weight for a C6 listed in the Estes catalog (4.0 ounces - the Saturn V would weigh in at 5.3 ounces with a C6-3 loaded). So my model will fly on an an Aerotech D10-3W or a Quest D16-4.

The melted part of my Saturn (Click to enlarge).The damage to the forward bulkhead (Click to enlarge).
However the thought of switching from a BP to a composite motor brought to mind my old Saturn 1B, so I dug it out of the box for a dust-off and a new inspection. After all, it would be a nice add if I could fix it up and fly it on the Apollo anniversary. The damage was as I remembered, but I figured gluing the escape tower (which was taped to the rocket - a rare bit of organization) would be easy with Plastic Weld and I could prevent further melting by installing a stuffer tube inside the model. This will preclude flying the Saturn on dual motors, but there are now plenty of 18 mm composites, so no great loss. I Frankensteined a stuffer out of a length of BT-20, with segments of BT50 and ST-10 at each end (the BT50 and ST10 tubes were chosen because they fit the bottom and top bulkhead openings). The stuffer tube was glued in using 15 minute epoxy - while this dried, I glued on the tower using Plastic Weld. The final steps in the repair were attaching a new shock cord to the pre-fab attach points and adding a few grams of clay in the nose to compensate for the weight of the tubes.

Assembled stuffer tube
(Click to enlarge).
Installed in the Saturn (Click to enlarge).
She's now ready to fly - I think I'll be using an Aerotech D21-4 for the flight.

The repaired Saturn 1B
(Click to enlarge).
July is looking to be a very fun month!

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