Thursday, May 31, 2007

Amateur Icelandic Rocketry

There is some nice amateur rocketry going on in Iceland. Magnus and Smari have built and flown some very nice hardware. You can see their stuff here. They recently fired a very nice looking 100mm motor that looks very similar to my 4 inch design. It looks like the nozzle got some damage, but I think it looks like it might be salvageable. Looking forward to seeing that video. Magnus has also recently started a rocketry forum.

Saturday, May 26, 2007

Four Inch Diameter SRM

This is a four inch diameter motor that I've been working on for a while now. This motor is very similar to the motor that I flew last month. Both motors used 6061-t6 aluminum for the casing and 12L14 steel for the nozzle. The grain geometry was also very similar, with the major difference being that this motor uses six segment instead of four. This motor has been fired twice now. Both firings occurred at the RRS's Mojave Test Area. I normally go out to the site the night before to do propellant/motor prep, then sleep in a tent on site that night. The first firing experienced a burn through in the casing. The motor fired well for most of the burn and damage was limited to the casing, so I was very pleased with the initial firing. I made several small changes to the design; first was reducing the diameter of the casting tubes/inhibitor slightly to accommodate an increase in the casting tube/inhibitor thickness of 15% , lastly the casing insulation thickness was increased by 25%. I consider the second firing to be successful. The ignition was a bit slow, due to much of the igniter material being expelled from the nozzle. The use of a pyrogen canister should solve this problem. I am pleased with the resulting ISP of 127 (ISP being a measure of propellant performance). The important thing for me was that the casing temperature didn't begin to rise until several seconds after the test indicating that the insulation was effective. Post test inspection revealed that the insulation had been breached in several places, but the video and temperature data do seem to support the idea that these breaches occurred post firing. I may still add a bit more insulation for added safety though.

Monday, May 21, 2007

Unusual Rockets

I regularly search on eBay for unusual rocket hardware. I found this intriguing auction a while back. I didn't turn up much info about this particular small sounding rocket. A quick Google search did turn up this info though...

"Another approach has been developed by Texaco Experiment Incorporated. Their rocket, named Cricket, uses a cold propellant to boost the rocket to an altitude of 3,000 feet. At peak altitude a parachute is deployed which allows the whole unit to descend intact. The propellant is acetone and dissolved CO 2. A 0.5-pound payload can be carried and the rocket is reusable at least 10 times. The launch system is simple and can be safely operated by untrained personnel. With additional altitude and payload capabilities, this system might well be adapted to the problem at hand."


Monday, May 14, 2007

Rocket Launch

My friend Chris was flying his plane near Big Bear, California this past Friday when he and his passenger saw this rocket launch East of their location. I was surprised to see the photo because it appears to be a much larger vehicle than what I would expect to see in that area, or maybe the vehicle is not as large as I think.

Saturday, May 12, 2007

More video from the April 28th launch

Here is a video taken by Matt Campbell. I also have some still images taken from the video which show some of the key moments. They are from top to bottom:

1. Last minute prep.
2. Arming of the Altimeter and timer.
3. Connecting the igniter.
4. Ignition.
5. Lift off.
6. Clearing the tower.
7. Rocket under way.

Wednesday, May 9, 2007

Motor Stats

I thought I'd post some quick stats on the motor that I flew on the 28th of April. The motor was designed to produce approximately 425 lbs of thrust for 2.2 seconds for a total impulse of nearly 950 lbs. The motor (nozzle, casing, bulkhead, snap rings, inhibitor, and casing liner) weighted in at 5.96 lbs. The propellant grain, consisting of 4 segments in a bates grain configuration, weighted in at 7.31 lbs, with a port/throat ratio of 1.5625. The propellant was mixed in a ratio of 65/17.5/17.5 (KnO3/Sorbitol/Sucrose) 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, purchased at Home Depot. The casing and bulkhead are fabricated of 6061-t6 aluminum. Using Richard Nakka's casing.xls the design safety factor was determined to be 2.2 with a burst saftey factor of 2.94. The nozzle is fabricated from 12L14 "leaded steel" and had a throat diameter of 0.64" and an expansion ratio of 12. There was no measurable throat erosion post firing and the nozzle appears to ready for another firing. When I took the motor apart post flight the insulation was nearly intact, having been breached near the bulkhead. The casing appears to be fine and there is no measurable deformation.

Monday, May 7, 2007

Launch video from May 20, 2006

Here is some of the video taken of the first time this yellow rocket was flown. In it's first flight it was flown with a smaller motor, no camera payload, and not boat tail. If you look closely at the video, you can see the shadow cast by the exhaust trail shooting out across the desert behind the launch tower. I also included a photo of both motors that I've flown in this rocket so far. The smaller motor uses steel EMT for the casing. The larger motor uses an aluminum casing and snap ring closures.

Saturday, May 5, 2007

The Camera

I was really happy with the video that I got from the launch, but haven't really mentioned the camera that I used. The camera was a Canon SD200 that I got off of eBay for $52. It was a little beat up, but it came with a 512MB card, and works quite well so I've been really pleased with it. With the 512MB card it will only record a few minutes of 640 x 480 video at 30 fps, so for the launch I bought a 2GB card; it was on sale at Best Buy for only about $30. With the 2GB card the recording time is extended to nearly 17 minutes. I made a simple cradle/camera bay for the camera and that was all there was to it. The camera bay had a one inch hole for the lens and a smaller hole 90 degrees away from the lens opening that allowed me to turn on the camera, start recording, and adjust the lens just prior to launch. In the pictures above you can see the tubes used for the camera bay being squared off on the lathe, the cradle that held the camera, and the finished rocket.

Friday, May 4, 2007

More pictures from last weekends launch.

Here's a couple of pictures from last weekend of the rocket at take off. These were taken by Chris Neuhahn.

Thursday, May 3, 2007

Shirra and Stafford by Paul Calle

New lathe chuck arrives

I purchased a "new", larger lathe chuck on eBay a while back and it arrived yesterday. I'm pretty happy with it. I will probably want to remove it from the back plate and take a really light cut on the back plate, then clean everything, and reassemble it. The "new" chuck is much tighter and smoother than my previous one; I think it's probably a better quality chuck. My previous chuck is a 6 inch and the new one is 8 inches. What's the connection to rocketry? Well, bigger rockets of course.

Wednesday, May 2, 2007

More photos from the launch on the 28th

My daughter Grace flew her first rocket at this launch. Here is a Picture taken by my friend Chris of Grace letting me check everything out one last time before loading it into the launch tower. That's Mom and little sister in the background. Dave Allday did a great job taking the picture of Gracie's rocket at take off. Unfortunately we didn't recover her rocket. I told her we'd make her another and she said "Okay Dad, but it should be bigger". Grace's rocket was powered by a c-400 motor and took off like it was shot out of a cannon.

OnBoard Video from the Camera Rocket

Here is the video from the rocket. From take-off to apogee the footage is real time, most of the decent from apogee back down to the ground has been cut, and the remaining decent has been gradually slowed down. Thanks to James for the edit. There was some weird behavior with the roll of the vehicle. I think it may have been caused by the vehicle going through transonic speeds. The rocket simmed to well above Mach 1.

Here are some stills that I pulled from the video; the first is the lake bed at Edwards Air Force base, I believe that the second one is the Honda test track, and the third is the only image that the video captured of the drogue parachute.

April 28th Launch

I have flown this rocket before and it flew very well (straight), so I decided to fly it again with the largest motor that I could construct to that would still fit into the aero shell. I also decided to add a video camera and a boat tail. Top two photos by Chris Neuhahn and bottom two by Dave Allday