United Technologies Center Rocket Motor

This item is currently up for auction on eBay. Unlike the actual (Altair?) motor that I found for sale on eBay recently, this one appears to be strictly a model, perhaps of an actual production motor. It does seem to be proportionally similar to the Altair motor. The model is described as being 15 inches tall with the embedded nozzle measuring 2 7/8 inches. It's not clear if the nozzle measurement is length or diameter. The current asking price seems pretty high, but as far as models go this one seems pretty nice.

Successful Launch!

While not the largest rocket I've ever launched at a meager 8lbs and 4 ounces and a mere 21 inches in length it was definitely in the top three; Big sisters Grace and Lily rounding out the top three. This one is known as Theodoor Stephen after two of his great uncles. Mom, Dad, and two previous launched projectiles all doing well.

Static Test Results

I finally got around to looking at the data from the static test from back in April. The motor was mostly comprised of hardware from a previous motor that I lengthened to make room for another propellant segment. That results in the initial Kn rising from 340 to 425. The other big difference was that I added 1% RIO to the propellant. I also changed the closure method from snap-rings to a bolt-ring closure designed for the increased chamber pressure. The propellant grain consisted of 5 segments in a bates grain configuration weighing 9.247 lbs with a port/throat ratio of 1.5625. The propellant was mixed in a ratio of 65/35/01 (KNO3/Sorbitol/RIO) and cast into 3" mailing tubes that have an ID of 3" and an OD of 3.125". The casing insulation consisted of four layers of rosin paper. The casing and bulkhead are fabricated of 6061-t6 aluminum. The nozzle is fabricated from 12L14 "leaded steel" and had a throat diameter of 0.64" and an expansion ratio of 12.

The total impulse was 1213 LB-Sec (5395 N-Sec.) making it a small M-class motor. I was also pleased to find that the calculated ISP was 131. Slightly higher than I expected given the fact that I didn't spend a lot of time premixing the propellant ingredients and used the KNO3 as received.

There was no measurable throat erosion post firing and the nozzle appears to ready for another firing. When I took the motor apart post test I found that the insulation was severely breached at the bulkhead end. I think that the higher chamber pressure created a much harsher environment for the insulation than I was expecting. The insulation breach resulted in a small blister in the casing about .125" in diameter and about .005" high. I'm happy to replace the casing since it was one of the most out of round 6061 tubes that I have ever purchased. The casing thickness provided for a fairly significant safety margin, so I'm considering pushing the design a bit by using a .065" walled casing which will allow the insulation to be more than doubled and should make for a very lightweight and powerful motor. Overall, I'm pretty pleased with the results.

Interesting Rocket Motor

I'm always scanning eBay for interesting or unusual rocketry related items and recently came across this motor on eBay. I've seen other interesting things before like this small sounding rocket that I saw last year. Occasionally something really interesting shows up like this composite motor I saw last week. Unfortunately I didn't win this auction, but at least the pictures are kind of cool. The description said that the motor had been acquired from Douglas Aircraft some years ago. the overall length is 60" and the diameter is approximately 18". The tag had the following info on it:

P/N AG659-61370 QTT3 #1, Owner-NASA, 6-25-69

Pressure Calibration System

T4 Change, Model DSV4B-1-1

USC Rocket Launch

Here is the video that I took this past weekend of USC's rocket. I placed the camera about six feet away from the launcher pointing towards the sky. It was two stages and got a bit squirrely at booster burn out. The booster was a P-class motor expected to deliver an average thrust of 1300 lb and the sustainer was an L-class motor. I didn't hear about the recovery. You can find out more about the USC rocket propulsion lab by clicking here.

Weekend Rocket Activities

This past weekend was full of rocketry. First off I was able to see the fifth Sugar Shot motor test over at the FAR site. Look for more details and photos on the Sugar Shot site as the post test information is reviewed and analyized. My photos of the firing can be seen here.

It was also one of the busiest Reaction Research Society launches over at the RRS site that I've been to in a while. In talking with some of the other members I found out that their online gallery area has had a number of additional photos added recently. I haven't checked it out yet, but I suspect there are some great photos there. You'll have to register to view the galleries, but that's simple enough to do. Some of the highlights of the day were seven successful Zn/S rockets flown by a group of middle school kids. A static test of a film cooled 4000lb thrust engine. USC flew a large two-stage rocket. A Zn/S rocket with two nozzles at the top. I also had a good test of a 600lb thrust motor that I will be posting details of in the weeks to come. All of my photos of the RRS activites can be seen here.

Blog maintenence/missing photos

I recently activated my Picasa web album which is were the images uploaded to Blogger are stored. In an attempt to clean up some duplicate images in that album I inadvertently broke a bunch of photo links to some in my earlier posts. I think I've got them all fixed now.