Monday Sep 24, 2007

First Launch

I finally launched my LOC Vulcanite rocket for the first time. The results were outstanding.

I blogged about my Vulcanite earlier this year. This rocket is 53" tall (4.5 ft, 135 cm) and weighs 32 oz (2 pounds, about 1 kg) before adding a motor. I painted it orange and black to make it more visible against blue sky or light clouds.

My goals for this rocket include:

  1. determining that it is flight worthy
  2. obtaining my Level 1 certification
  3. gaining experience with high-power motors
  4. flying a rocket to one mile (1.6 km) altitude
  5. if it seems that the rocket will survive Mach 1, attempt to do so
On the day I first launched it, I achieved (1), (2) and (3). The first launch, and L1 certification attempt, was on an AeroTech H73J. This motor weighs 10 ounces when ready for launch, and is about 6" (15 cm) long. It provides 16 pounds of force at liftoff, sufficient to launch this rocket easily, but not so much that I have far to walk if it decides to become a "cruise missile" by turning and flying horizontally.

The results were gratifying.

(When I take pictures of a launch, I press the shutter as soon as I see any vertical movement, which resulted in a well-composed picture. At least it did this time...)

According to the on-board altimeter I added, it flew to 1,584 feet (480 m). More importantly, it flew almost perfectly straight up, and the 24-inch parachute returned it safely to Earth not far away from the launch rail. However, it seems that the delay I chose - the time before the parachute is ejected - was not long enough. With the correct delay, the rocket would have flown higher.

Beaming with success, I decided that the next launch would begin to test the limits of this rocket. I chose an I218R - an 8-inch (20 cm) motor with almost twice the total impulse of the previous motor. (Think of total impulse as the total force exerted while the motor is burning.) Even though I knew it would fly much higher, the wind was very light that day, so I didn't expect to walk far to recover it.

With this motor, the Vulcanite flew to 4,469 feet (1.35 km)! Also impressive was its maximum speed: over 500 MPH (800 km/h). You can see that in the picture to the right: I have an itchy shutter finger, but the rocket launched so fast I missed it entirely!

Unfortunately, although the nose cone ejected properly, the parachute never came out. The two ends of the rocket, connected by an elastic cord, fell over 4,000 feet to the ground. Fortunately, the launch area was an empty corn field with large clods of dirt which had been softened by rain the day before. The only damage was a partial crack in one plywood fin. A little sanding, some new epoxy, and it should fly again.

To one mile?

Wednesday May 09, 2007

There's no 'k' in 'rocs'

One of my many hobbies is rocketry. Just a guess, but you've probably heard of it. If not, check out the two main rocketry associations in the USA: the National Association of Rocketry and Tripoli Rocketry Asociation. The latter is an international organization, with groups ("prefectures") in North America, Europe, Israel and Australia.

I have always been interested in rockets, ever since watching man land on the Moon back in 1969. I launched "hobby rockets" in the late 1970's, but only recently re-visited the hobby. I found that things had changed. First, they are called 'rocs' now. Also, video cameras are common, and the web is everywhere: here is a video of a large high-power rocket and a chapter in the saga of Nibbles the Astro Cat.

My first "mid-power" rocket was an Aerotech Arreaux. It flew on motors of different sizes, up to a G33, and to a maximum altitude of 2,000 feet (600m). It usually carries a sampling altimeter because... well, just 'because.'

The picture to the right is my Arreaux after a few flights. It is about 43" (109cm) tall.

Moving on (and up...) this year I am building a Loc-Precision Vulcanite kit. My goals for this rocket are to obtain my Level 1 Certification and to fly it to an altitude over one mile (1.6km). While doing that the rocket would exceed Mach 1. Achieving my L1 certification allows me to purchase H and I rocket motors. I chose the altitude goal "because it's there."

The picture to the right is my Vulcanite during construction. It is about 53" (135cm) tall. The red metal cylinder to its right is a machined aluminum rocket motor casing for a J motor, which can also be used to launch this roc. I might attempt to get my Level 2 certification, which would allow me to buy J motors.

If you ever launched hobby rockets, you may recognize the C6-5 motor to the right of the J casing. Back in the 1970's we thought that was a big motor... but a J motor can produce over 100 pounds (440 newtons) of thrust at liftoff, and a total impulse (thrust measured over time) of 100-150 times that of a C motor. Just in case I fly the Vulcanite on a J, I strengthened the structural components. "You never know."


Jeff Victor writes this blog to help you understand Oracle's Solaris and virtualization technologies.

The views expressed on this blog are my own and do not necessarily reflect the views of Oracle.


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