SM-2, Block III Missile Construction Photos

The blue "O" motor casing was delivered on 9 April by Jeff at Loki Research.  The craftsmanship and attention to detail in this motor is astounding.  This is Loki's 40,000 ns 51" long, 6" diameter motor.

It is standing next to its 48" tall PML motor mount tube for comparison.  Thank you Jeff for supporting my LDRS project!

Build of the SM-2, Bk III began in earnest on Saturday, 15 April when I received the first fiberglass tube from Performance Rocketry.

4-15-06:  This is the first of several custom fiberglass airframes delivered by Curtis at Performance Rocketry.  The tube is 13.45" in diameter and 0.120" thick.  I could not be happier with the result.  I hope Curtis was happy too!  The tubes are absolutely beautiful, sanded and cut with precision.

In total there will be 4, 48" airframes delivered along with one 48" fiberglass coupler and a one-off 2:1 Ogive fiberglass nose cone.  Thank you Curtis for supporting my LDRS project!

With real measurements in hand, I immediately went to work cutting rings and bulkheads.

Due to the size, I cut the rings on a scroll saw.  After I cut the first one, I sanded it until it was just the right size to slip into the new airframe.  This became my pattern for the rest of the rings.

When I receive the airframe coupler, I can cut the electronics bay bulkheads.

Here's a look at the main fins of the SM-2.  I had previously cut them out of 9 layer, 1/2" Baltic Birch Plywood.

The left hand edge mates with the motor mount tube inside the airframe.

The lower left portion of this fin is what forms the boat tail at the bottom of the rocket.

The fins still need to be beveled to an airfoil shape and fiber glassed.

So, with a few rings cut, Let's test fit the fins to measure for the aft ring diameter.  Next step is to lay down lines on the motor mount and airframe tube for the fins.  Everything must be true for the assembly to install properly.

The entire motor mount assembly will be completely assembled as a finished unit before it is permanently installed inside the airframe.  The fins will be bolted onto the centering rings using threaded inserts

The boat tail will be completed using expanding foam and fiberglass.

There will be a lot more test fitting before this unit is ready for installation.

Here's one of my two new (used) 28' diameter C-9 military parachutes.  This one has absolutely no rips, tears or holes.  The other has two small holes.  Both were bought on an ebay auction.  One of these will be riding in the SM-2.  Can you guess which one?

Now back to the basics.  Let's get this thing straight and true...

Drilling holes in the main fins to accept threaded inserts.

Here's another test fit with the fins bolted to the centering rings.  The fins and motor mount are further "locked" into place with the close fitting slots cut into the fiberglass airframe.  I will also add threaded inserts into the centering rings for additional "thru-fuselage" fastening.  This is all on top of Epoxy.

Here's a look at the middle part of the wings that will be attached to the upper section of the booster.  These are about 55" long.  I cheated a little bit and only made them 5.5" wide instead of 6".  Helps a bit on the CP location without sacrificing realism.

The Payload section has a 13" extension of these.

The lower portion of the booster also has an extension connecting these to the main fins.

Now it's time to glass!

And glass... 

And glass....

Motor Retention was provisioned for in an extention of the motor mount tube.  1/2" ply with a 3/8" all-thread secured by a t-nut on one side and two jam nuts on the other.

 Location of motor retention "cap".  Sorry Ed, this one's "fixed" for a 51" motor.

Showing the all-thread.  The All-thread screws into the first 1" of the motor's forward bulkhead providing significant resistance to falling out after motor burn out!

4 layers of glass was added to the motor mount extension/motor retention mechanism.

The Airframe was slotted using a Dremel and a diamond cutting wheel.  Thanks Curtis, this was like cutting through butter!

 The cuts turned out to be very accurate and a good tight fit.

 Test fitting the fin can to the airframe.  Looks good!

 Now it's time to test fit the rest of the booster section, draw lines to mark the location of the stringer fins, and drill holes to bolt the fins to the airframe.  Yes, I said bolt!

The booster section airframe is made up of two 48" fiberglass tubes, with a 7" airframe sandwiched between them using a 25" section of fiberglass coupler.

Here's how I am bolting the fins on.  Using threaded inserts for wood.

Here you can see the screws used to bolt the fins on from the inside of the airframe.  The hole pattern was created by taking a left over length of 1/2" 9-ply plywood about 1/4" wide and the length of the longest fin and drilling holes at the points I desired.  I used this as a tooling pattern to drill pilot holes into the airframe and the fins.  This ensured they would be in alignment.  I used 10-24 flathead bolts for most of the attachment points, but for those that will be exposed to the payload bay/e-bay coupler, I used a smaller 8-32 under-cut flathead bolt. 

You can also see here small wood blocks which also contain the threaded inserts to strengthen the coupler junction with the airframe sections.

So, here's my progress as of 5-16-06.  The booster is nearly complete with two stringer fins attached.  The Electronics bay is roughed out.

I'll add the last two stringer fins tonight.  After that, I will test fit the section one more time and drill holes to attach the upper section onto the lower section.  I'll JB weld on more threaded insert blocks and measure for the last length of stringer fins that connect the upper fins to the main fins at the bottom.  I'll also drill holes to bolt these last fins to the lower booster section.

 Progress as of 5-17-06 11pm.

5-18-06:  Finished the aft end.  Added aft motor retention T-nuts and added the aft rail button.  Reinforced the aft rail button with plywood tying it into the motor mount tube.

5-19-06 My first try at using expanding foam from Giant Leap Rocketry...not a pretty sight.  User error most likely.  Looks like I'll have to fill in the gaps before I start sanding.  Uneven expansion.  More like a 10:1 expansion rather than 25-30:1.

5-20-06:  Work plan is to finish the boat tail.

NEWS FLASH!  Curtis at Performance Rocketry is shipping my last needed fiberglass components on Monday!  I should receive by Tuesday or Wednesday.

5-21-06:  Finished the boat tail with sanding, bondo, sanding, bondo, sanding, bondo, sanding, sanding and fiberglass....  Still need to sand more...

5-22-06:  Watched 24.  Did you?

5-23-06:  Started working on a custom decal order with Scott Binder at Binder Sign & Design.

5-24-06:  Cut and prepped the last of the stringer fins to the lower booster section.  Bolted in place. 

Attached and epoxied the last centering ring to the motor mount.  Had to hold off on this one until the stringer fins were bolted on (chicken & egg problem).  You can see the flush end of the top end stainless flat head screws used, in one of these pictures.

These two sections are now ready for permanent joining -- tomorrow...

5-25-06

Received the last custom fiberglass tube and one-off custom nose cone from Curtis at Performance Rocketry.  This project is nearly complete!

The nose cone is absolutely beautiful.  The nose cone is smooth and strong, primed and ready for paint.  The base even came with the U-bolt already in place. I had planned to add my own plywood bulkhead and U-bolt but this one came complete. Curtis really does high quality work!

Here's the first complete test fit.  Both Rail buttons are on.  The electronics bay is on.  Upper fins are bolted onto the payload bay. 

Still have not glued the two booster sections together yet.  I'm a bit nervous at the finality of it and not being able to access the internal parts.  And the weight!

The dry weight without motor has come up 4 pounds shy of the RockSim calculated weight!  Only thing is the nosecone weighed in at a hefty 18 pounds!  No need now for lead in the nose! CP has a margin of 1.6.  But now I'm going to be 14-15 pounds over my originally planned takeoff weight.  Now it's 203 pounds!  No more supersonic flight....

Prior to joining the two halves of the booster section, I decided to remove the forward motor retainer "cap".  I got nervous that if it were not dead center, I might not be able to remove the motor very easily.  Also, during joining of the two halves, I was off by about 1/8" to 3/16" in aligning the upper fins to the lower fins.  With resins curing, I was not able to rotate the two sections into alignment.  In a desperate attempt to rotate the sections relative to eachother, I used drywall screws in each of the wooden blocks located inside the coupler as a lever.  The net effect of this was to knock about half of them off of their mount.  To fix all the above, I had to sand the fins using a hand held belt sander, apply more bondo, sand, fill, sand...  Some of the bolts that run between the airframe and coupler now have no backing, but were JB welded in place as best I could.  I still need to find a way to remove the loose blocks.

Recovered from a serious laptop crash.  Ouch.

Here's how I painted the rocket.  Curtis placed a metal rod through the nosecone.  I used a 12" steel nail through the back gate of my utility trailer to support the nose.  At the rear, I shoved a garden hoe up the tail and rested the blade end onto my gas grill.  The rocket then became a rotisserie!  Since I don't have any fancy painting capability, I used "rattle cans".

The rocket has been painted but still lacks decals.  Some touch up paint is needed.  I am in process of installing the electronics.

I've been very frustrated in trying to send a simple graphics file attachment to have decals made.  It's been weeks in the making. 

Thanks in a very large part to Ed Rowe and Mike McBurnett, the motor has been mixed, poured, cast, cut and fitted into the Loki Motor casing.  My focus now is on transport of all my gear from Virginia to Texas...

6-22-06:  Performed an ejection test of the nosecone.  Used 8g in the payload bay.  Nosecone with 8, 1/2" 4-40 nylon screws blew off like a rocket.  Screws cut tracks through the soft sides of the one off nosecone.  I'll keep the airframe holes, but will have to rotate the cone and drill new holes into the cone.  The recoil of the charge damaged the aft e-bay bulkhead.  I have rebuilt it using 1/2" ply.

Decals were finally purchased from my local Sign-A-Rama.  Decals will go on by Saturday after a bit of touch-up paint has dried.

Final Picture: