The motor extension tube from the kit was a bit long and not needed for my purposes (it was added to the kit to accommodate the long hybrid motors). Although I originally decided to remove only 2” from its length I decided I would rather have the additional room in the airframe for the drouge chute and harness and so 4” was removed and a solid bulkhead added to the top.
The Kevlar shock cords were attached to the U-bolts on both sides of the lower motor tube centering rings using an Anchor knot and the 6” of remaining cord was firmly held together with electrical tape.
The completed motor tube assembly is shown here ready to be mounted into the tailcone.
A small bulkhead with U-bolt was mounted into the nose cone. The bulkhead was sanded to a contour that will mate flush against the inside of the nosecone. The bulkhead was then glued inside the nose with Epoxo-88 paste in order to get a good fit and to seal the spaces between the bulkhead and the irregular surface of the fiberglass nosecone. A good amount of West Systems epoxy was then poured in to make the bulkhead attachment as strong as possible (don’t want the nosecone flying off on its own!).
January 23-24, 2009
Epoxy fillets were generously applied to all ring/tube joints.
After reviewing the instructions and test fitting the placement of the coupler (between the tailcone and the booster airframe) it was necessary to cut 1/4” x 9/8” slots in the coupler to allow the forward fins to clear the coupler. I also decided to shorten the motor extension by 2” to provide more room in the booster airframe for the drouge chute and kevlar cords. The photo shows the coupler extending past the fin slots. It was this piece that was cut out to allow the coupler to extend the full 7 1/2” into the airframe.
January 17-19, 2009
A 1/4” hole was drilled through the airframe and the space between the airframe and the eBay was filled with approximately 3.5 ozs. of expanding foam. After the foam cured the hole was drilled into the eBay and a section of brass tubing was epoxied in to provide the static port for the altimeters.
After reviewing the maximum thrust of the Loki M1882 and discussing motor selections via emails with Kent Burnett of Giant Leap (the designer of the Talon-6) it was determined that the M1882 would provide a bit too much punch for the Talon. With this in mind I decided to use the Aerotech M1315 reload instead. Since it is well known that Aerotech hardware will work with the Slimline retainer I decided to stay with Slimline motor retainer as supplied with the Talon-6 kit. The retainer was attached to the motor tube with J-B Weld.
I wanted the aft section of the motor tube to have a little more support so I added a centering ring about 6 inches from the motor retainer. The edges of the ring were sanded to a taper that would fit the curve of the tailcone.
A critical part of the Talon is the forward motor tube ring assembly that supports the motor tube at its center point and also provides the anchor points for the tubular kevlar cords that hold the aft section to the mid section. It is this part that will take the force during separation at apogee. Since the original set of rings (cut to the ID of the tailcone) would not pass through the neck of the tailcone (the fiber-glassing on the inside where the tailcone and the coupler are attached) a new set of rings were supplied by the vendor. The shims were mounted to the inside of the tailcone where the new rings will be ultimately be epoxied when the motor tube assembly is attached inside the tailcone.
Here is a view of the shims with one of the two centering rings placed to support the shims while the epoxy cures.
The two new rings were glued together and then sanded to fit the shims. Once the fit was verified U-hooks were added to the rings and they were glued to the proper location on the motor tube. Epoxy fillets were applied to all mounting points where the rings meet the motor tube.
January 11, 2009
Completed eBay and collar assembly is expoxied into the upper airframe. Epoxy will be poured into the seam between the tube wall and the exterior rings to form fillets.
The coupler harness and bulkhead is completed.
January 3, 2009
Initial construction has started. The Electronics Bay (e-bay) and collar assemblies are shown to the right. Although the assembly of the e-bay and collar assemblies are essentially per the instructions, I need enough room in the e-bay to hold two altimeters and batteries. The original separation of the threaded rods (as per the provided Giant Leap Rocketry 3.9" Av Bay) needed to be increased to 2.5”.
The original holes in the e-bay bulkheads were filled with cotton soaked in epoxy and new holes drilled to accommodate the 2.5” spacing of the threaded rods. The supplied external endcaps were scraped and new ones made.
Here is the completed e-bay assembly.
Lesson Learned: Using the Talon-6 e-bay assembly on my “Helios” uncovered a bit of a problem. Since the kevlar harness could not be removed from the collar it was VERY difficult to maneuver the endcaps into place from within the airframe. The modification here was to add 1/4” Quik Links that will allow the attachment of the harness after the e-bay endcaps are in place.
I was a bit concerned that the root edge of the fins would not be supported very well by just epoxying them through the body tube slots. I usually build up the fin can first, cut the body tube slots through to the aft end and then slide the slotted body tube on over the fins. But since I needed to mount fins in the tailcone I wouldn’t be able to have it’s slots cut through. And I didn’t want to cut the aft body tube either as it only has a short section at the aft end. So I mounted 3/8” square hardwood strips along the inner motor tub to provide a channel for the fins to slide into thus providing not only ample area for epoxy to pool up and provide strength but also to provide additional strength along the motor tube itself since each wood strip would butt up against the centering rings.
Here the forward fins (and 1/4” plywood sheets) are used to check the alignment of the hardwood strips before they are permanently mounted to the motor tube.
Each set of fin guides are mounted and then checked to make sure the alignment was good. Once completed all the fins were placed in the slots for the final check before the motor tube assembly is glued into the tailcone.
The fins are made of composite-fiberglass/honeycomb boards with custom machined edging. The edging is glued with Polyurethane glue.
Epoxy fillets were added to the fin-airframe juncture. Tape was used at each end to prevent the epoxy from leaking off the edge.
March 15-17, 2009
Each set of fins was mounted into the airframe and tailcone as a pair. Epoxy was poured through the airframe slots into the hardwood channels that were mounted earlier. Then the fins were placed through the slots and the root edge firmly pressed into the epoxy filled channels. Clamps and a length of angle bar were used to maintain alignment of the forward and aft fins.
March 14, 2009
The access holes for the switches were located and drilled. Although they were measured twice they were misaligned by about 1/8”. Some spacers were added to the sled to compensate.
The main airframe was epoxied into the tailcone followed by the coupler centering ring. Ample epoxy was poured in after forming a nice set of fillets.
March 7, 2009
With the main airframe completed and the arrival of the TAC-9C parachute from Giant Leap I decided to perform a ground test. The TAC-9C parachute is very large and the forward internal airframe space is only 18”. Although the original kit design called for a piston ejection system there simply wasn’t sufficient room in the airframe to accommodate it. After 45 minutes of packing and repacking I was finally able to get a Kevlar parachute protector, the TAC-9C, the Kevlar harnesses and hardware all in the airframe. This took the entire 18” of the forward airframe and 12” inside the nose! There wasn’t a millimeter of space left.
After some calculation of the volume I determined that 5g of BP should provide the required force to break the 4 shear pins and “push the laundry out”. This was a critical test of the Talon for if it didn’t succeed I may have had to go with a smaller parachute and risk the higher descent velocity. As it turned out the test was a complete success. The airframe was held at a 60 degree angle and the BP charge sent the nose cone flying about 20 feet, depositing the chute and hardware just in front as can be seen in the photo.
March 6, 2009
Electronics sled and switch enclosure were completed out of 3/16” plywood.
The sled is completed. Because of tight dimensions for mounting the switchbox there wasn’t sufficient room for the 1/4” cardboard tubes to extend along the sides of the switchbox. Fiberglass cloth was used to provide support for the all-thread rods at this point.
Here is a view of the opposite side where the batteries will be mounted. All wood surfaces were painted with 2-part 5-min epoxy and 91% alcohol to provide a sealed surface. .
The Talon is completed! Here she is with custom decal and gold fin tip trim (not easily seen in these photos however). All that remains is the mounting and wiring of the electronics and then off to the field for an April 17th flight.
April 5, 2009
The primer was applied, wet sanded, patched and the first coat of paint applied. Whew, the sanding job is not as perfect as I would like but the April 17th launch date is getting close! The Nose Cone is complete; the booster section needs the black paint applied to the fins and the upper section needs a coat of black paint. Once the paint is completed the decals will be applied and the chrome fin tips will be applied.