SStS Motor Work Update

I've nearly completed the work on the MidBulkHead modifications, all I have left to do is to countersink the 24 holes on the outside edge.  This draft of the motor design shows how the CSD or disk is held by the MBH.

Sugar Shot motor work

I've begun work on modifying some existing hardware for a new SStS motor. This design will incorporate a new non-pyrotechnic device to separate the two motor chambers.  In theory the Chamber Separator Disk has a number of benefits over the pyrotechnic "plug".  This document explains the concept and you can see some of the analysis  that Ben Brockert has been working on here.  Pretty simple in theory.  This newest motor will also feature a return to the Bates grain configuration.  For more info on this motor and other recent updates, please check the Sugar Shot weekly activity reports located at the top of this page.

This is the modified MidBulkhead showing the area that the CSD will be retained.

I've begun indexing the new screw locations and will then have to drill and tap them before moving to the next task which is modify the existing motor casing.

TR-1 motor casing

The summer has been busy so there hasn't been a lot of Rocketry getting done.  I have been working on a test rig for the SStS program that will be used to test tensile strength of propellant which will have varies additives designed to increase its strength.  This is a pretty interesting idea and the results could help open up some new possabilites for sugar based propellants.  The TR-1 rocket motor hasn't moved forward much, but I have gotten the 4" EMT (seen above) for the motor casing.   I'm hoping to be able to start construction of that motor in earnest soon.

Hermes Solid Rocket Motor

I bought number of Thiokol publicity/advertising brochures on ebay a while ago. There are a lot of interesting photos including the one above that shows Harold W. Richey posing with the "milestone" Hermes rocket motor which was fired in December of 1951. In that firing the motor fired for 41.2 seconds and produced 17,172 lbs of thrust. Fourteen months later it went on to successfully power the RV-A-10 rocket from Cape Canaveral. The Hermes is credited with validating the concept of large solid fuel motors. There is also a series of photos that show the process of prepping and loading the shuttle SRM's that I'll post later.

SStS Test Parts Finished

I finished the test parts that I was working on and Rick picked them up yesterday afternoon.  He and Paul were going attempt the first test this weekend.  I was scrambling to get the parts done in time for this weekend, the steel bulkhead took a bit more time than anticipated, but hopefully the parts serve their purpose well. 
Here I'm tapping the steel bulkhead:

I was starting the tap in the v-block on the drill press to get it started straight then laying it flat to get a good enough grip on it to turn the tap.  The whole process of tapping the bulkheads took longer than I was expecting, but when you're tapping or threading it's definitely best not to rush.

Here are the finished parts:

TR-1 Motor

I haven't had a chance to do much work on the TR-1 motor...I'm satisfied with the design and am ready to start machining.  I just need to finish machining the hardware that I mentioned in my previous post.

I modeled the nozzle in 3D.  I find that this helps with the machining if I can move the part around and think how best to machine it.

 The design is similar to the MiniSShot nozzles that I machined in that it consists of two main pieces.  There were a number of reasons that we chose to construct the MiniSShot nozzle in two sections, but for the TR-1 motor the decision was made simply to ease fabrication.  Constructing the nozzle from two pieces allows me to use some stock that I had on hand and more importantly significantly reduces the amount of material that I'll need to remove.  I have a piece of 1018 for the shoulder portion of the nozzle and some 12L14 for the convergent/divergent  piece.

SStS Machining

I'm currently trying to finish up a test set-up for the SStS project that will allow us to test a single grain segment with the star core that we've used for the last two motor firings.  It's simply a short section of the casing material with two end closures, one made of Aluminum and the other of steel.   Looks roughly like this:

I used the new center drill indexing the steel bulkhead and the difference was immediately noticeable.  Don't use dull tools kids!  Anyway, after realizing what a difference it made I decided that i needed to stock up on the # 1 size center drills. I managed to find a set of four # 1 center drills on Ebay.  I paid about what I did for the set from Harbor Freight, so a great deal!

Here is a shot that shows the bulkhead after I indexed it.  You can see the Dremel set-up in the tool holder and the indexing holes on the main gear of the lathe.  You can also see the indexing pin in the casting between the back of the chuck and the gear.

Here are a couple of shots showing the machining progression on this piece.  This is the first time in a while that I've done something this larger using 1018 steel and it's definitely slower that using 12L14 steel. 

Harbor Freight

I'm starting to be able to make more time for rocketry and inevitably that means more machining.  In the past year or so most of the machining that I've done has consisted of indexing and drilling holes...a lot of indexing.  I use a Dremel rotary tool  in the lathes tool holder to mark the hole locations in whatever stock that I'm indexing.  The Dremel takes a 1/8" bit which corresponds to a #1 center drill.  I have a bunch of center drills but only one of them was a #1 so it borne the brunt of the abuse over the course of this last year indexing well over 300 hole locations.  I've noticed the last couple of times that I used this set-up that the bit was getting dull and last weekend indexing with it I felt that the accuracy was be compromised.  I figured that I would order a bunch of #1 bits from McMaster-Carr, but they were $14 a piece, fortunately Harbor Freight carried a set for $7.  Don't get me wrong, McMaster-Carr is great, they have almost anything you could ever need, some things you don't know that you need yet, the site functions well and is full of useful info, customer service and shipping are great, but a similar set (theirs has 6 bits vs 5) cost over $200.  I opted for Harbor Freight, but it took a few visits before I found them in stock.  I've actually been spending a lot of time  restocking, cleaning, and organizing... tools, batteries, bits, etc.

Space X

Congratulations to Space X.  Everything seems set for them to complete this historic journey to becoming the first commercial company to dock to the International Space Station.  Best of luck in the coming days.

Metal Purchase

I picked up some metal from Industrial Metal Supply before work yesterday. I got some 7" diameter 6061 and 1018 for a test motor I'm building for SStS and some 5" diameter stock for the TR-1 motor.

TR-1 Rocket Motor initial CAD

Here is our initial CAD of the new TR-1 motor.  Pretty much the same layout as my first N-class motor.  Bates grain consisting of six segments, with a half inch spacing between segments.  The motor will utilize approximately 28 lbs of propellant.  I will be making the nozzle out of two sections to help reduce the machining time and so that I can use metal stock that I have on hand.

TR-1 Rocket

With my sons first visit to the desert to view a rocket launch and to help out with the static test of the Sugar Shot to Space's latest motor a few weeks behind us, we've decided to build a rocket.  The last new motor that I designed, built and flew was this one:

That was about two years ago and Theo doesn't remember it at all.  That was a new motor that used an existing aero shell that had to be extended a bit to fit the new motor.  The whole process of designing and building a rocket is fun for me and actually getting out and flying it is the icing on the cake. Since Theo loves tinkering out in the garage as much as I do, we're going to design and build this from scratch.  We don't plan on re purposing any existing pieces, other than maybe some of the electronics.   While it may take a little more time with Theo's "help".  Did I ever tell you about the time I thought he was cleaning up on the other side of the garage but was actually bungee cording my motorcycles together.  Despite any setbacks we may encounter, I'm really looking forward to going through the whole process with him.  I'll try and document the entire process here. 

Theo's requirements are that the rocket be big and orange...maybe with some blue.  With that in mind the motor is going to be based on this N-class motor that I designed, built, and tested a while back.  You can see that motor by going here.  The biggest difference is that the TR-1 motor will utilize EMT for the motor casing.  As you may or may not know, EMT is one of my favorite motor casing materials.  I'm not sure why, I think it's because of other peoples attitudes towards it.  I  discussed my feelings about EMT, or steel in general during the development of my last motor (the one pictured above), you can read that by clicking here if you're interested. The biggest advantage that I'll get from EMT for this motor is that I can use a standard four inch mailing tube for a casting tube.  Four inch EMT actually has an OD of 4.5" and with a wall thickness of 0.083" the ID should be around 4.334".  That should allow for a few wraps of rosin paper to be used as an insulator, like I did in the my other design.  Though with EMT this isn't necessary for the casing, but will help cut down on the heat transferred to the aeroshell. My initial  4inch motor had and ID of four inches and I was rolling the casting tubes by hand, very time consuming and messy.  Using Richard Nakka's "casing" spreadsheet I found that 4 inch EMT has a burst pressure of 2573psi.  With a design pressure of 1050 PSI I end up with a design safety factor of 1.7 and a burst safety factor of 2.45, pretty conservative.

I did an initial SRM design, summarized here:

While my previous N-class motor was on the edge of the M/N class this new design ends up solidly in the middle of the N-class and should provide for an awesome experience.

More to come...

First Launch

I was out at the FAR site helping out with a SStS static firing and took my son along.  It was his first time to the site and I think he loved it.  I certainly did.  I had a lot of fun watching him explore the area.  He scoured the facility looking for "treasure" at one point I looked in the back of the van and found a pile of this treasure consisting of a broken cinder block, a one inch iron rod, half a dozen rocks (one of which was cool enough that we actually brought it home), and various nuts, bolts, washers, and pieces of scrap metal.  We saw a couple of launches and  a few static test, all in all a good day.

Souvenirs found on one of the Lunar Lander Challenge pads

Guarding the SStS motor prior to testing

Running for cover

Boiler Plate Motor Parts

I did some simple modifications to the SStS DDS BPS Motor in anticipation of an upcoming firing.  This is a nice looking motor and I can't wait for the firing...should be cool!  Here is a photo of one of the parts in the lathe and the same part being test fitted in the motor casing.

Nice Engine Firing!

I happend across this video earlier today and I couldn't help but notice that the mountains in the background looked awfully familar.  Once I heard the countdown, I knew I was right.  Ten years or so ago I'd heard the same voice calmly proclaim "test complete" following a massive cato during the largest solid rocket motor firing I have ever witnessed.  Cool stuff!

Nike Ajax Restoration

I ran across this blog detailing a Nike Ajax missile restoration effort currentlly taking place at the former Nike battery site NY-56 in Hancock New Jersey.

http://ny56nikeajax.blogspot.com/

I've seen one of these up close at the local VFW...big, cool missle. There are numerous pics of a Nike missile being dissassembled including this one that shows how the fins are mounted.

Star Shaped Core

I've been trying to come up with a way to create a star shaped core without the need for a machined
mandrel and a way that would also reduce the risk of having to deal with a stuck mandrel.  The above image
illustrates what I came up with.  I'm currently making a version of this jig that has several features added in so that I can actually try to cast a grain with this set-up. The most notable features are a star shape on the base that helps seal the bottom so that propellant doesn't seep under and into the core, a hole in the center of the base to ease the installation of the tape, and a secondary top cap which helps to keep everything centered.

Motor Casing complete

Completed Motor casing for SStS motor test.

Casing continued...

The new casing for the DDS boilerplate motor is nearly complete, just a little more sanding on the bulkhead end (on the right in the photo), and it's ready to go.

Shuttle Launch

The Shuttle Launch Like You Have Never HEARD It Before Thanks to Skywalker Sound.  Great video, and accompanying sounds, of a shuttle launch.   I suggest that you play it loud.

 http://gizmodo.com/5893612/the-shuttle-launch-like-you-never-heard-it-before

SStS casing part three

Unfortunately the existing casing for the latest motor, a single-burn boiler plate motor, was accidentally damaged prior to testing, so I'm fabricating a new one.  Nothing new; cut to length, true ends, drill, drill, drill...
Hoping to make it to the firing and take lots of pics.