Tuesday, November 15, 2011

Goddard Prototype?

I saw this on ebay this morning.  The seller suggests that this is an early regen engine prototype that came out of  Robert Goddard's workshop.  That would be cool!  The seller makes no claims of having any proof to go with it and with a price tag of $325,000 and a short 3 day inspection period before considering the sale final, it seems unlikely that a buyer will come forward.  It does seem that with enough time, that some research and material testing it would be possible to determine if it were at least plausable...

Thursday, October 20, 2011

SStS motor casing

This new casing is a bit longer than the previous casing that I made and it really dwarfs my lathe.  It's coming along nicely though.  In the top photo you can just make out the Dremel attached to the tool post, it holds a #1 center drill that I use to mark the hole locations in the casing.  The Dremel isn't the ideal tool for this; not enough power and the #1 bit is so small I'm always concerned that it'll break.  It is enough to mark the locations though.  The next step, seen in the 2nd photo, it to use my little drill press and a larger #3 center bit to drill through the casing.  Then it's just a matter of enlarging the holes to the final diameter.  I like to do this in two steps, drilling to nearly the final diameter, then finishing off to the required diameter as the final step.  This results in clean, accurate holes.

Thursday, October 13, 2011

SStS Motor Casing

I have purchased a piece of tube to fabricate a new motor casing for the Sugar Shot to Space DSS effort.   The DSS motor and test setup were among the finest I've ever seen, it's a shame that the motor failed but the team has a good idea of the failure mode and how to avoid it.  Here is the tube before being cut to length and drilled for the nozzle and bulkhead.

Just when I thought I was working on a large motor, I saw this truck on the freeway hauling a large number of Titan strap-on booster motors.  OK, fine!  Maybe this is just a sprinkler system for a new industrial building.  It's all in how you  use them...

Wednesday, April 6, 2011


I just recieved an old rocket motor off of eBay. Sometimes refered to as JATO motors (jet assisted takeoff motor) or by the more accuarate acronym RATO (rocket assisted takeoff motors) these small motors have always caught my interest. Mostly because they were among the first, if not the first, rocket motors that were mass produced. The urban ledgend about the guy that attached several of these to his car doesn't hurt the appeal either. I can't find much information about this particular motor, so if anyone knows anything about them I'd love to hear from you. The markings on the case read Rocket Motor M3, Lot PA-79-9.

Wednesday, March 23, 2011


I saw this Estes Vashon V-1 cold power rocket engine for sale on eBay recently. I don't ever remember seeing these as a kid but I think I would have been drawn to it. A blackpowder motor is cool but this stuff looks like "real" rocket hardware. I found this 1969 Popular Mechanics article describing the system.
It's very similar to the Cricket sounding rocket that I found on eBay a while back.

Tuesday, March 22, 2011

Update (Sidewinder Nozzle Comparison)

This past weekend was busy and didn't leave a lot of time for rocketry. I did manage to get the first half of the new nozzle off the lathe and start on the second half. The first half of the nozzle is pretty hefty; I have to remind myself that this motor will produce over 1,600 lbs of thrust with a total impulse of around 8,000 lbs, so a nozzle that weighs in at 4-5 pounds isn't really an issue. In the photo it's next to an early Sidewinder missile nozzle (on the left). Compared to that nozzle it doesn't seem too hefty at all...

Monday, March 14, 2011

Motor Update

Not much progress this weekend. I've finalized the nozzle design and finished machining the first half of the nozzle. I orderd some stuff from McMaster-Carr including the screws that I'll need to retain the nozzle and bulkhead in the casing, those that will attatch the two nozzle pieces, and the O-rings. I still need to pick up some steel bar stock for the ring/shoulder half of the nozzle.
Here is a render of what the finsihed nozzle will look like:

Wednesday, March 9, 2011

More Nozzle Machining...

I'm working on the convergent side of the nozzle now and I've updated the design a bit. Not much of a change; just using a couple of angles leading into the throat region vs one and thinning out the excess material while still leaving enough where the nozzle will take the most abuse.

Monday, March 7, 2011

More Nozzle Machining

The nozzle is progressing well; I finished the divergent section and should be ready to finish off the other side in the next few days. I was only able to bore it out to a depth of about 5 inches, so I left the throat diameter rough. I'll take it to the final dimension once I'm working from the other side and don't have to have the boring bar extended nearly so far from the tool holder; I should be able to get a cleaner finish that way.

Wednesday, March 2, 2011

New Motor Nozzle

I started on the nozzle last night and realized that this really is going to be a big motor. The piece of metal that I started with for this one piece of the nozzle started out at 16 lbs. the other piece starts out at around 4 lbs which means that I'll need to machine away some 17 lbs of metal to end up with a nozzle that comes in at around 3lbs. Lots of metal shavings...

Tuesday, March 1, 2011

New Rocket Motor

I recently fabricated the motor casing for a boilerplate version of the next motor in the series for the SStS project. This next phase of the SStS project represents a significant step up in scale; here is the material needed for the casing of this new test motor:

The casing material is steel and pretty hefty, but should work well for this particular motor. I had to get a bit creative as each of the two sections was far longer than the bed of my lathe. It was fun and I ended up being pleased with the results. Here is a section of tube on the lathe and a nearly completed casing section for the SStS motor on my workbench:

I ended up with about four feet of tubing left over and figured that it should become a rocket motor :)My overall design was driven by the length of tubing that I had remaining. Here is the SRM output:

The casing has been completed and I've started cutting metal for the nozzle. I'm making the nozzle in two pieces, to ease the fabrication and to use metal stock that I had on hand. It's a pretty straight forward all steel design. The Divergent section is a little short with an expansion ratio of around 5.5:1, but again this was dictated by the metal stock that I had on hand. The downside is about a 02% reduction in the total impulse, but the upside is probably a six or seven hour reduction in fabrication time. I'll take it!

Everything else is being made with ease of fabrication in mind and I'm hoping to fly it this fall.

More to come...

Thursday, February 10, 2011


I ran a half marathon this past weekend which wouldn't normally have anything to do with rocketry. This race however was in Pasadena, CA and about halfway through the race I realized that I was running through the Arroy Seco wash right behind the Jet Propulsion Laboratory . Ok, maybe not exciting for you, but this is the exact spot were Jack Parsons, Theodore VonKarman, Frank Malina were testing their rocket motors in the late 30's. Those experiments eventually led to the founding of Aerojet corporation and JPL in the 40's.

Tuesday, January 25, 2011

SStS set to start work on next phase

Sugar shot to Space is set to begin work on the next phase of motor/rocket development called DoubleShot. With a motor coming in at around 6 1/2 inches in diameter and utilizing approximately 200 pounds of propellant it should be a good show.