SStS TM-3 MOTOR CASE UPDATE

 

 

I've got the SStS TM-1 motor case nearly finished.  The screw hole locations are all indexed and the ends trued up so all that is left is to drill them out and a little polishing.

SStS TM-3 MOTOR CASING

I started on the TM-3 motor tube this morning.  It absolutely dwarfs my lathe, but being aluminum instead of steel it's much easier to work with than the previous DSS motor cases that I've worked on. I only need to index the retaining screw locations and true the ends.   I should be able to finish this tonight, then I'll get to work on the other half of the TR-1 nozzle.  With approximately 90 lbs of propellant this motor should produce a total impulse that fits it into a P-Class designation.

TR-1 ROCKET UPDATE

 

 

I finished all  of the lathe operations for the nozzle ring.  When I took it off the lathe I was struck by how heavy it was.   It doesn't really matter for a static test, but I decided to go back in and remove a bit of the excess material.  The amount of material that was removed (drawing above) reduced the parts weight by nearly 30%.  It will also make it easier to drill and tap the twelve screw hole locations as they are no longer blind holes.  There are still a few areas I can pare down but I'll hold off for now.
I'm going to take a quick break from the TR-1 motor and work on the SStS TM-3 motor casing which seems to be coming together quite quickly.  This is a pretty large O or P-class motor which is about as big a "Sugar" motor as I've ever heard of.  It shouldn't take me long to finish work on the casing and then I'll get back to work on the TR-1 motor.

TR-1 MOTOR UPDATE

Slow progress is still progress right?  In anticipation of completing the current part soon, I've prepped the 12L14 steel bar for the nozzles other section.  A couple more short sessions and I should have the nozzle ring complete.  I've also started drawing for the actual rocket, nose cone, fins, etc.  so look for those soon.

TR-1 MOTOR UPDATE

I'm making slow but steady progress.  I managed to get the nozzle ring close to final diameter last night.  I'm hoping to get this piece finished in the next day or two.   The other parts will be either 12L14 steel or 6061 t-6 aluminum, so fabrication should speed up once this part it finished. I mentioned the relative ease of machining 12L14 versus 1018 yesterday, the thing I forgot to mention was clean-up.  With 1018 I tend to get these long strands of barbed steel wool that sticks to everything.  It tends to shoot off the lathe in every direction, it gets in my hair, wound around the chuck, or onto the tool holder. With 12L14 I tend to get a neat pile of chips right under the cutting tool which is much easier to clean up.  It's the little things...

GROVER AEROSPACE

I went though my links to see what other people were doing.  Some are less active than they use to be, some more.  I got rid of a couple of links and I also found some new sites.  One that I found to be particularly interesting is James Grover's site.  I hadn't read very far before I found this sentence that he had written in the response to a question.  "I don't have a lathe so I "turned" the parts with a hand drill and made the o-ring grooves with a hack saw blade."  To me that sentence exemplifies the can do spirit of a true amateur experimental rocketeer.  Anyway, lots of interesting stuff on his site and worth checking out.

TR-1 MOTOR UPDATE

Theo and I had a little garage time this morning.   We managed to get the nozzle ring indexed for the six screws that connect the two nozzle pieces.  I indexed twelve locations just as a precaution, in  case one gets messed up somehow.  If I break a tap off and can't get the broken piece out, for instance.  Not likely with a 1/4" tap, but it didn't take much extra time. The part was then flipped and I began cutting it down the the correct diameter.  I can't wait to finish this part and move onto the easier machining 12L14 steel.  On the McMaster-Carr site they rate the machinability of steels in one of four groups from fair to excellent.  Common 1018 steel is rated as good and 12L14 as excellent.  The addition of a small amount of lead is what improves the machinaility of 12L14 so I take a few more precautions when machining it to keep it off  my hands.  I'd use 1215 steel which uses sulfur and phosphorus instead of lead to achieve the same machinability, but I never seem to be able to find it locally or on ebay at a good price like I can 12L14.  

TR-1 MOTOR UPDATE

I didn't get much time at the lathe this weekend, just enough to face the divergent side of this piece and cut the relief that the other half of the nozzle fits into.  I need to index the screw locations, then I can flip the piece and finish it off.  I did realize during the weekend that I didn't have a complete set of drawings for this motor.  It had been so long since I designed this motor and I was incorrectly thinking that I had designed this piece to work with another nozzle divergent piece that I had already fabricated.  You can see that nozzle here, it's the one on the right.  At one point this weekend I saw the two motor casings sitting next to one another and immediately thought "wait a second, that other motor is way bigger...that nozzle piece can't work with the TR-1 motor!"  After checking my earlier designs I realized that I had drawn a preliminary version of the needed part.  I double checked everything, made some minor adjustments to the design of both pieces and now have a full set of drawings for this design.

I may still decide to take some excess weight out of the nozzle ring as it's heavier than it needs to be.  Then again, it doesn't really matter for the static test so I may just get the important stuff done then move onto the next piece. It would be beneficial to remove weight from the aft end of the rocket before the flight so I'm sure I'll do it before then.   I'm machining the nozzle ring out of 1018 which is noticeably tougher to machine than the 12L14 that I'll be using for the divergent piece.  Once you've machined 12L14 steel, all other steel seems like a chore!

TR-1 MOTOR UPDATE

I started on the nozzle ring this morning.  I drilled out the center, starting with a center bit and working up to a 1" diameter bit.  The larger drill bits remove a lot of material quickly, but an inch is about the limit for my lathe.  Next I'll bore out the center to the right diameter. Then I'll face it, cut the relief that the divergent section fits into, and index the holes for the six screws that hold the two sections together.  Then I'll flip the piece. Once flipped I can finish it off to the correct diameter and cut the convergent section.  Lastly I'll add the o-ring gland and index the twelve screw locations for the screws that hold it in the casing.

SStS MOTOR CASING (DSS TM-3)

The aluminum tube for the DSS-TM-3 SStS motor arrived yesterday.  I'm just indexing/drilling the screw holes so not much work for me.  DSS TM-3 motor?  OK, it's getting tough to keep track of all the motors as there are more than a few in varies stages of construction and testing.  The motor is a single burn (half of the dual phase concept) that is intended to serve as a flight motor for the avionics package once successfully tested.  The design calls for approximately 90 lbs (41 Kg) of propellant.  Hopefully that flight will occur later this year.  As always, check the weekly reports  on the Sugar shot to Space site for more detailed information.

CHARLES M. PARKIN, JR.

I've collected a lot of rocketry stuff over the years, maybe none as cool as this book.  The Rocket Handbook for Amateurs by Lieutenant Colonel Charles M. Parkins.  I saw a copy of this book sell on ebay claiming to be a first edition.   Maybe it was...maybe it wasn't.  The listing included numerous photos of the book, but suspect is the fact that the copyright page had the lower third cut off, right were mine clearly states that its a "second impression".  I don't really care that mine is a second edition, but I paid WAY less that buyer of the other book paid.  I bought the book for the information it contained and maybe a little for the nostalgia of being able to read a book from the golden age of amateur rocketry.  In any case my copy has something even better than being a first edition, an inscription from the author.  It looks to me like the inscription is to someone with the initials H.C. I'd love to know who that is.

Charles M. Parkin, Jr.  as he is described in the book:
Rocket expert, U.S. Army Engineer, Research and Development Laboratories, Fort Belvoir, Virginia; Founder of Youth Science Corps; President, American Rocket Society, Washington D.C. chapter.

In the later chapters of the book, he describes a small rocket which utilizes a sugar based propellant. I've  often thought that it would be fun to build that rocket exactly to the specification in the book and then actually fly it.
Maybe I will do that some day...

TR-1 MOTOR CASING

With this drawing, I now pretty much have all the drawings that I need to begin cutting metal in earnest.  I plan to go back and update these drawings.  I don't really need a drawing for the bulkhead as it's identical to the nozzle ring in thickness, o-ring gland placement, and retaining screw locations.

TR-1 PROPELLANT SEGMENT DESIGN

I plan to use a 4" ULINE mailing tube as the casting tube/inhibitor for this motor. This particular tube has a wall thickness of 0.080" and allows for a bit of insulation to fit between the propellant segments and the casing wall.  The motor is designed to use a propellant grain consisting of six segments.  Each segment should weigh approximately 4.75 lbs (2.15 kg)  for a total propellant load of approximately  28.5 lbs (13 kg).

TR-1 ROCKET MOTOR UPDATE

It been almost exactly one year since I started this motor...far too long.  SStS has been going very slowly and in spite of some recent progress, I suspect that the the way forward will continue to be a slow progression.  Back when I started getting really involved with amateur rocketry thirteen years or so ago, I was designing, making, testing, and flying much more frequently.  I think in those early days, once I joined the Reaction Research Society there was so much excitement in going to the launches.  The first event that I went to included zinc/sulfur, LOX/kerosene, HTPB, and sugar .  Within the next few months I saw many more of those and added steam, HTP, and a variety  of hybrids, good times.  I don't know that I can get back to that level of activity anytime soon, but Theo definitely enjoyed the desert, the rockets, and the people so we should make a point to go more than once a year.  With that in mind I'm making a conscious effort to finish the TR-1 motor ASAP.

Here is the next part to be made. 

This is a fairly heavy motor, but it won't matter.  With 1000 lbs of thrust there is no doubt in my mind that it will get itself off the ground when it's time to.  The purpose is to build something relatively simple and at low cost, and to sharpen my skills before moving on to a larger project that I've been toying with for the past 10 years or so.  There is some excess material in this design, so the part could go through a weight reduction process, but there is really no point for a static test.

SUGAR SHOT TO SPACE SUCCESSFUL FIRING

The Sugar shot to Space project had a much needed successful firing this past weekend.  After the spectacular CATO of the impressive DoubleSShot motor nearly one year ago there was a lot of discussion and investigation into what exactly happened and why.  This test represents the first in a series that will lead SStS to the successful firing of one of the largest amateur motors of all time.  Certainly the largest "Sugar" motor of all time.
Congratulations to Rick Maschek, Paul Avery, and Richard Nakka for their dedication and perseverance, as well as the many other numerous volunteers that have contributed to the project.