LOC Hawk 7.5'' Build Thread

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jmuck78

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I ordered the LOC Precision 7.5'' Hawk around Thanksgiving and immediately opened the box without bothering to take pictures. I have already done a few steps, such as assembling the RNWS, but I think I can still do a build thread for the bulk of the remaining steps. I have created a sim file (openrocket) that I will include in this post (since I didn't see one anywhere else). For whatever reason, I can't seem to convert the openrocket file to a useable Rocksim file, but I haven't really put the much effort into it either. I've seen other build threads with the first half a dozen or so posts reserved for the future build steps, so I will attempt to follow that method here (although I have no idea how many posts I will need).

This is also my first build thread so bear with me as I muddle through (although I have completed my L3 documentation, which probably counts as a build thread).

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jmuck78

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Motor Mount Subassembly

The LOC Hawk uses 5 plywood centering rings constructed of 1/4'' LOC plywood. The forward-most centering ring is sized to fit inside the 15inch coupler that joins the two 30 inch sections of 7.67 inch body tube that make up the booster section of the rocket. The forward centering ring will host the two 1/4-20 U-Bolt attachments for the recovery harness.

The second and third centering rings are sized to fit inside the main body tube and are notched to receive the fin tabs. The second and third rings attach to the forward and aft edges of the fin tabs at the fin slot locations in the body tube.
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The fourth and fifth rings make up the forward and aft part of the tail cone. The fourth ring is sized to fit inside a 1.5 inch long piece of 7.5 inch coupler that the tailcone (a modified stiffy coupler) inserts into. The aft end of the tailcone joins to the motor mount using a 5.5 inch diameter ring.
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The planned order of steps here is as follows:
1) Rough up the motor mount tube.
2) Dry fit the tail-cone assembly and aft notched centering ring (CR3), insert in to the body tube, and mark the location of the bottom of CR3. The fin slots are 12 inches long, so I marked the motor tube 12 inches forward of the mark corresponding to the bottom of CR3. This mark indicates the location of the top of CR2. The tail-cone is 7 and an 1/8 from end to end, inclusive of the band that sits inside the body tube, so the second mark that indicates the top of CR2 is 19 and 1/8 inches from the aft end of the motor tube. These marks allow the aft end of the motor tube, aft centering ring (CR5), and the aft end of the tail cone to be flush. I can then use either the 98 mm aeropack retainer or the LOC z-clips as motor retention.
3) Attach the two 1/4-20 stainless steel U-Bolts to the forward most centering ring and attach that ring (CR1) to the 98 mm motor tube about a half inch to an inch below the forward most edge of the motor tube.
4) Attach the forward most notched centering ring (CR2) to the motor tube so that the FWD side of the ring hits the 19 1/8inch mark.

The subassembly now looks like this:
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Because the top centering ring sits inside the tube coupler, I am going to attach the motor mount subassembly to the coupler before I epoxy the coupler or motor mount to the body tube. Attaching the coupler to CR1 first allows me to epoxy a fillet on the AFT (inside) side of CR1 before I install the motor assembly to the body tube. I will have access to the FWD side of CR1 to epoxy a fillet there as well as access to the AFT side of CR2 to epoxy a fillet there. I should be able to build an epoxy fillet on the FWD side of CR2 by adding epoxy on the top of the CR before I insert it to the body tube and allowing gravity to work on the epoxy. If that seems unsatisfactory, I can drill some holes into the airframe and insert epoxy to form a fillet the same way I do on fiberglass rockets.

5) The top of CR1 needs to be 13.5 inches from the top of the coupler in order for CR2 to line up with the fin slots (based on the dry fit). I inserted the coupler and motor mount assembly into the body tube and used the body tube to keep the pieces aligned while I adjusted the relative height of CR1 and the coupler. I used some CA to tack the CR and coupler together before I epoxy the coupler to the motor mount.IMG_7404.jpg

6) I have added the epoxy fillets between CR1 and the tube coupler. Once that has cured, I will be able to install the motor mount/coupler sub assembly into the booster section airframe.

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jmuck78

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Reusable Nose Weight System / Nose Cone

The nose cone arrived with the bottom/base of the nose cone already cut off and open. The Reusable Nose Weight System (RNWS) utilizes a centering ring with a motor mount tube. The centering rings have four holes for the included T-nuts.

I tapped the t-nuts in place and covered the back with epoxy (protecting the holes with some painters tape) to prevent epoxy from getting in to the threaded holes. While that cured, I roughed up the inside of the nose cone at the shoulder and inside near the tip. I then buttered the inside of the nose cone shoulder with epoxy and inserted the centering ring, pulling it towards the shoulder of the cone until it was firmly in place. Once dry, I added some epoxy fillets around the perimeter of the plywood/plastic interface. With the same batch of epoxy, I inserted the forward bulkhead into the forward side of the motor mount tube, putting epoxy fillets on both sides.

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Once that epoxy was cured, I poured some epoxy into the bottom of the cone and inserted the motor mount tube, bulkhead-size first, through the hole in the CR and into the nose cone, letting the nose cone rest fat side down to allow the epoxy to fillet the joint between the motor mount tube and the nose cone. Once cured, I added an epoxy fillet around the joint between the motor mount tube and the CR.

The rest of the RNWS system consists of two cartridges - one weight cartridge and one spacer cartridge - which are essentially coupler tubes of the same length. The weight cartridge has a forward bulkhead and a rear bulkhead with a harness anchor. I epoxied in the forward bulkhead just inside the forward end of the tube, adding fillets on both sides.

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Once that cured, I mixed a batch of clear 5 minute epoxy and the appropriate amount of copper BBs (which is what I use for nose weights), in this case 500 grams of BBs. I poured the BB/epoxy slurry in to the weight cartridge and because I happen to have an extra one laying around, I added another plywood bulkhead floating on top of the epoxy/BB slurry. Once that cured, I epoxied in the third bulkhead with the harness anchor so that the harness anchor was completely below the edge of the tube. The reason for recessing the harness anchor is to allow me to use the spacer tube as a tracker bay later on.

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Once the weight cartridge is cured, the cartridges can be integrated into the nose cone. The trick here is that the harness has to pass through the retaining bulkhead (the one that holds all of the components in to the nose cone), the spacer tube, and then attach to the weight cartridge (in that order).

The weight cartridge goes in first, then the spacer, and then the retaining bulkhead is screwed in to the CR already epoxied to the nose cone using four 1/4-20 philips screws and washers.

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jmuck78

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Booster Section and Fins

I used a router table with a 75 degree bevel to bevel the edges of the fins. The results are good, but not great as the outside edge of the fins had some concavity (I don't mean warped). To be fair, these are large pieces of 3/8 inch plywood almost 4 feet long.

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The epoxy on the motor mount has now cured and I am ready to insert the motor mount subassembly (tube coupler + motor tube + first two centering rings) into the lower booster section. I mixed up a batch of RocketPoxy and slathered the inside of the booster 5 inches or so deep from the forward side of the tube and dropped the motor subassembly into the booster section. I cleaned up any epoxy that had migrated into the fin loc gaps of CR2 and smoothed out the fillet from the aft end of CR2.

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I let that cure for a while and then repeated the process with the second section of 30 inch booster section and slid it over the forward end of the coupler, making sure to align the marks on the upper tube with the alignment marks I had made previously so that the fin slots on the upper and lower tubes would line up correctly.

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I took some pictures, stood back to admire the progress, and then went back one more time to look inside the tube to see if there were any epoxy drips and wipe down the excess epoxy with a rag. It was here that I realized I had made a mistake. My arm was long enough to reach in only to about the top of the coupler - not the bottom where the two U-bolts for attaching the harness were located. I stretched down to see if I could reach the U-bolts, and considered an aparatus for hooking a quick link on to the U-Bolt - but I quickly realized that even if I could hook the U-Bolt with a quick link - there is no way I could tighten the quicklink to secure it.

So, I pulled the upper tube off - which was slow and difficult since the tubes are large and I had almost no leverage. I got the tubes separated, found a bit of 1 inch Kevlar Strap that I had leftover from my Wildman Extreme build, and quickly tied the Kevlar strap to the two U-Bolts to create a Y-Harness. I also applied some epoxy to the knots to keep them from unraveling. I then reinstalled the upper tube and hung the Y-harness over the side of the tube.

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The next step now is to fiberglass the booster section using a long fiberglass sock that should also help hold the two sections of the booster together. Normally, I would install the fins and use the access at the bottom to apply internal fin fillets, install the Aft centering ring, and add a motor retainer. Here, I would like the tail cone and both sections of the booster to be one continuous length of fiberglass. So, in order to be able to do that AND install internal fin fillets before I close up the motor mount compartment, I am going to leave extra length of the sock that is dry while I epoxy the portion from the bottom of the fin slots to the top of the booster section, then install the fins, apply fin fillets, install the aft centering ring and tailcone, and then roll the excess fiberglass cloth down the tail cone and apply the next batch of resin.
 
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jmuck78

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Tail Cone

UPDATE 1/26: I was unhappy with the initial tailcone installation, so I cut it out and started over. The replacement installation is captured in post #48.

While the epoxy is curing on the motor mount assembly, I started the tail cone assembly. The tail cone assembly, as noted above, consists of the following parts:

1) Tail Cone, which is a LOC "Stiffy" Coupler that is cut so that when collapsed one end will be about 5.5 inches in diameter.
2) 1.5 inch long section of coupler
3) Forward 98 mm Centering Ring (CR4) that sits inside the 1.5 inch long coupler section
4) 5.5 inch diameter centering ring that will connect the small end of the tail cone to the motor mount tube.

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The initial assembly will combine the first three of these elements above by applying a layer of RocketPoxy to the inside of the small coupler section, inserting the larger centering ring so that the forward side of the centering ring is flush with the forward edge of the coupler, and then inserting the tailcone in to the coupler.

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I then applied a fillet inside the tail cone where it meets the centering ring.

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The three components should be firmly joined together.

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I will wait to attach the final centering ring and close the tail cone until this assembly is mated to the motor tube when the motor tube is epoxied to the airframe.

Installed the tail cone and epoxied it in place. The tail cone only went in about half as far as it should have - it seems to have frozen in place during insertion and left an extra 1/2 inch of tail cone hanging out. I'm fairly certain this won't affect the strength of the airframe, so I decided to leave it.

I installed the Aeropack 98 mm flanged retainer to the final, aft-most center ring by match-drilling the holes from the flange to the 5.37 inch (OD) centering ring with the ring clamped to the CR as closely aligned as I could get it.

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The Tail Cone is permanently installed, but I am going to add one more internal CR to shore up the cracked CR inside the Tail Cone (or Boat Tail).

Here is the final fit check before I start epoxying the final two CRs into the Boat Tail. The CR with the Aeropack retainer sits inside the boat tail / tail cone by about 3/4 of an inch, so the motor will still stick out of the rear of the rocket a bit.

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jmuck78

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Fiberglassing the Tubes

I'm using the giant leap "sock", which technically isn't fiberglass, but will add strength similar to fiberglass - and more importantly will mean I don't have to fill the spirals on a 7.5 inch diameter by 9 foot tall rocket. The sock is equivalent to about 3 or 4 oz fiberglass cloth.

I used two saw horses and a long piece of PVC to suspend the rocket horizontally to allow me to roll the rocket as the epoxy cures. I used an extra long section of the sock to allow me to glass the tail cone into the same mesh once I complete the fin installation. Whether or not this is worth the added complexity of having to fight around the sock to add the internal fillets remains to be seen.

I was using Aeropoxy laminating resin but ran out of it part way through the glass process, so I used some Bob Smith finishing epoxy, which is also used for laminating composites, but probably not as good as the Aeropoxy.

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I used an exacto knife to manually cut out the fin slots once the epoxy was in the leather stage.

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I still need to glass the payload bay as well as the avionics bay switch band - and I haven't yet figured out how to fiberglass a 1 inch band.

UPDATE 1/20/2019 I fiberglassed the payload tube using the same methodology as above - except this time I made sure I had enough Aeropoxy to complete the whole tube.
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UPDATE 1/27/2019 After replacing the mis-aligned tailcone (my fault) with a new part, I was able to close up the tailcone. The epoxy for the tailcone closure has cured, so its time to fiberglass the tailcone. The tailcone is going to bear the brunt of the landings, and any sort of oblique landing on the edge of the tailcone is going to have concentrate the impact load in a small area and at an undesireable angle. So, I am using 3.5 inch fiberglass cloth for the tailcone instead of the non-fiberglass cloth I used for the main airframe. I am also using West Systems Epoxy instead of Aeropoxy.

To get the right shape for the tail cone, I used an online calculator (https://www.blocklayer.com/print-diagrams.aspx) to produce a flat pattern of the tailcone based on the as-installed measurements. I printed out the tailcone flat pattern and used it to cut out the fiberglass shape.

Image 1-27-19 at 9.38 PM.jpg

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Once the epoxy cures here, I can trim the excess and fill in the small ridge between the aft end of the airframe and the tailcone.
 
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jmuck78

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Fin Installation

Once the glass was cured on the booster section, I was able to instal the first fin, which was a little more challenging than I was expecting just due to the size and flexibility of the fins, and the challenge in trying to clamp the large pieces together.

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Adding the fin fillets with that excess sock in the way is going to be frustrating, so I may trim it off and just glass the tail cone separately once its installed [Update] I did remove the excess sock at the aft end. It really was in the way with the internal fillets, which were complicated enough as is.

I let that first fin cure overnight, and installed the remaining fins today. After installing the remaining fins, I noticed that the first fin is not aligned correctly. I tried to pop it off to realign it, but the epoxy had cured and I feared I might permanently damage the motor mount if I forced it, so I'll have to live with the misalignment.

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Once the initial fin attachments were cured, I started doing the fillets. There are 2 external and 4 internal for each fin times 4 fins means 24 fillets. While the rocket is fixed in one horizontal position, I will do 2 external fillets, two internal fillets to the motor, and two internal fillets to the airframe all at the same time, then rotate the rocket 180 degrees and repeat. This way I can do the six fillets that have gravity in the right direction and then rotate the rocket. Even with the fin roots tacked to the motor mount tube, these fins are still loose at the forward end and will be loose until the external fillets are completed.

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Here's the initial round of fillets using an incredible amount of Rocket Poxy (I used something like 350 grams of epoxy just for these first 6 fillets).


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Also, I have drilled the holes for the rail buttons but will wait to install them until I complete all of the fin fillets and do some sanding.

Update 1/15/19: I have completed all of the internal and external fin fillets and have installed the rail buttons. I also installed the aft centering ring with the loc-n-fin notches that mate to the tabs on the aft side of the fins. Once that centering ring (CR3) was installed, I was able to install the tail cone subassembly (see post #5 above) and epoxy it in place at the motor tube and aft end of the airframe. I have left the final centering ring off and have yet to seal up the tail cone.

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jmuck78

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Recovery System and Electronics Bay


I wanted to make the electronics bay modular enough that I could reuse it in several different rockets, particularly the LOC VII and the LOC Hawk, but also in the extended Mega Magg I built a long time ago that was built with motor deployment as the recovery method. This electronics bay ended up being a bit heavier than I had expected, primarily due to the replacement of two of the three 450 mAh LiPo batteries with an 1000 mAh LiPo and a 1300 mAh LiPo. After having to stretch (with a ladder) to arm the electronics on my Wildman Extreme, I also wanted to use the wireless arming capability of the Eggtimer Quantum. The other design consideration was that the LOC VII is not fiberglassed, while the LOC Hawk is. So, in order to make this e-bay work for both, I had to either live with the slight difference in tube diameter due to the fiberglass, or make two different ebay containers and line up the switch holes perfectly in both. Wireless arming solved that problem since I no longer need to line up the switch holes in the vent band. I can use the same bulkheads and sled, I will just use a different coupler+switch band, which is easy to swap between flights - not that I expect to be able to fly both the LOC VII and the LOC Hawk on the same weekend since I only have so much space in the car.

Given those constraints, I elected to use the following:
  • Eggtimer Quantum as the primary
  • Eggtimer Classic + Eggtimer WiFi switch as the back up
  • Eggfinder TX (which I don't have yet) as the optional on-sled tracker.
  • Three 2S LiPo batteries - one 450 mAh, one 1000 mAh, and one 1300 mAh.

I have assigned the 450 mAh battery to the eggfinder TX (~ 6 hrs of runtime), the 1300 mAh battery to the WiFi Switch + Eggtimer Classic (should last about 12 hours for just the switch), and the 1000 mAh battery to the Quantum (should last "all day" according to the users guide).

I had also paid the price recently on another rocket for accidentally leaving the LiPo batteries connected to an Eggtimer TRS, and have two dead LiPo batteries as a result. I decided I should install two manual switches to allow me to connect the batteries and still have an easier method of disconnected them without having to disconnect the connectors. I won't be able to access the screw switches from outside the rocket, unless I decide I need to drill the holes to do so, but being able to flip the switches makes bench top testing substantially easier.

Since I'm going to (eventually) integrate an Eggfinder TX onto the sled, I added an RP-SMA cable to the main bulkhead that will allow me to mount a 900 MHz antenna on the outside of the electronics bay, which should help minimize interference from the two all-three rods inside the electronics bay.

Notes:

  • I mounted the three electronics components to the plywood sled using #4 nylon standoffs and #4 nylon screws.
  • The batteries were attached to the sled with 3 large zip ties (each) and mounted down the center of the sled.
  • I also attached the WiFi passwords so that I don't lose them (unless I lose the rocket, of course).
  • For the switches, I used to missile works screw switches and just glued them to the sled with CA. The switches are connecterized so I can by-pass them altogether if I decide I don't need them.
  • For charging, I plan to bring the sled to the charger and just leave the batteries attached unless it becomes necessary to replace one of the batteries.
  • Final build weight for the electronics bay (excluding only the Eggfinder TX) is about 2100 grams.

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jmuck78

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Priming and Painting

The finishing process for this rocket is going to look something like this:
1) Fill in the obvious areas on the fins with Bondo and sand that down.
2) Sand the fin fillets and look for holes to fill with Bondo, sand again
3) Apply a thin coat of West Systems Finishing Epoxy to the fins and and sand that down
4) Apply primer, fill, sand, apply primer, fill, etc.
5) Apply final colors (White Body, Black Fins/Tailcone)

Here's the booster section after step 3:

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And After step 4:

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I decided to go with a stock-ish white with black fins color scheme:

After the white coat:
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Masking and painting the fins / tailcone:
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Final:
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jmuck78

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Transportation

I ended up renting a U-Haul Trailer to transport the rocket to the launch site. I might have been able to fit the rocket in our Mazda CX-9, but the trip is a lot more comfortable for the kids if they don't have to share the back with all of the rockets and launch supplies.
 
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Launch Report:

The ROC Launch at Lucerne Dry Lake on July 20th, 2019 was our celebration of the 50th anniversary of the first men to walk on the moon. While this particular rocket wasn't intended to be a tribute, I was nonetheless inspired by the moon landings and the subsequent NASA Shuttle Flights when I was a kid, so I was happy to take part with any kind of rocket, as long as it went up.

The weather was good when we got to the launch site and the wind was calm. I immediately started prep on the LOC Hawk to get it launched before it too hot, but by the time I got everything ready, the wind had picked up quite a bit (despite the weather predictions to the contrary). I had planned to launch the rocket with a 60 inch recon recovery chute, but as I was packing the rocket to go I reweighed it and decided that the 36 lb dry weight of the rocket was going to be too much for the chute designed for a 21 lb rocket, so I used the 10 ft chute originally supplied with the rocket, reasoning that an oversized chute wasn't going to be a big deal for a dual deploy setup.

I had also learned that the large amount of nose weight could defeat the three #2 shear pins used to hold the nose attached to the payload bay when I launched the LOC VII using the same nose weight (RWNS), so I doubled the number of shear pins.

The predicted height with the M1297W Aerotech Motor was about 4800 ft or so. I loaded the 46 lb rocket on to the launcher (after what seemed like a much longer walk to the pad than I remember).

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The rocket launched cleanly, but did have a noticeably "waggle" as it took off. It was unclear if that waggle was due to the wind or some other workmanship issue, but the rocket did go in the general direction of "up".

The deployment charge did fire at apogee, but the main also deployed at the same time. This rocket used the same electronics bay as the LOC VII, which also had that issue, but after ground deployment testing didn't show any cross channel deployments, I'm speculating that the large weight in the nose still provided enough inertia to defeat the 6 #2 shear pins, and I really should be using #4 shear pins instead. This wouldn't have been much of an issue, except the wind was just below that 20 mph limit, and the rocket drifted about a mile, landing on the other side of the road from the launch site. Still no big deal, I just had further to drive to pick it up.

As we got close to the road, we noticed the wind continued to drag the rocket at a pretty healthy pace along the lake bed. The wind continued to drag it for another mile or so until the rocket hit a gully and embedded the forward end of the booster into the gully wall. It took a lot of effort to pull in the chute, and frankly, if the rocket hadn't been anchored into the gully wall, I don't think I would have been able to bring it down, never mind be able to catch it.

While I think the damage is reparable, I will have to lengthen the booster section by about 8 inches or so to allow a coupler, tube extension, and enough room for the electronics bay. I am probably just going to replace the payload section. The nose cone has cosmetic damage.

Oddly, both rail buttons were broken. There weren't any other impact signs in the vicinity and the rocket appeared to ride on the fins like sled rails while the parachute pulled the rocket on the ground, so I am curious if the rail buttons could have been damaged during the launch and if that was why the rocket "waggled" on its way up.

All in all, it was a good launch, with a tough, exhausting recovery. I think it will launch again some day once I get around to repairing it.

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jmuck78

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I still have a couple of outstanding design questions, so I'll pose my design questions below and see what feedback I get.

Motor Mount: The rocket design requires a 98 mm motor mount in order to accommodate the fin tabs and tailcone. I had wanted to preserve the ability to launch with a large 54 mm motor (the RNWS allows me to tune the rocket for the motor), i.e. a K805 or L1000. I could either permanently epoxy in a 75 mm motor tube in to the 98 mm motor tube (and if you look at the picture above, I have a 75 mm motor mount tube with centering rings sized for the 98 mm motor mount tube), or use the 75 mm motor mount tube as a temporary adapter. The thrust would be transferred entirely through the bottom thrust ring on the 75 mm motor mount, which seems like a single point failure to me. Alternatively, I give up on the 54 mm and just accept that this rocket is going to take at least a 75 mm motor to launch (using the aerotech 75 mm to 98 mm adapter).

Motor Retainer: The answer to this question depends on the first. I generally like the Aeropack retainers, and using a 98 mm motor retainer would allow me to use the 75 mm to 98 mm aerotech adapter. Using the 98 mm Aeropack retainer probably eliminates the 54 mm motor option though as I can't quite work out how to use a 75 mm motor mount tube as an adapter with an Aeropack retainer.

E-bay Switch Band: The electronics bay for this rocket is a 15 inch long LOC e-bay with the electronics part about 7.5 inches long, and it's biased to either the FWD end or AFT end of the ebay coupler. So, my normal approach of locating the switch band in the exact center of the ebay would mean the switch band is right on top of the plywood bulkhead at the center of the ebay. I can either bias the switch band two or three inches to the FWD or AFT of the coupler, which means one side is very short either inside the booster or inside the payload bay. Alternatively, I can try to cut the "stiffy" coupler and center the ebay, but make an even cut on a coupler that size is challenging to get exactly right. Another option is to put the switch hole in the booster section and just use the switch band to transfer load.

Thoughts?
 

KenC

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You can nest Aeropack adapters 98 to 75 and 75 to 54. I've flown a L1000 DMS and a K700 in my 7.5" FG L3 project. No problems just get all the pieces in the right place. That gives maximum flexibility for that M2500 you'll want to fly later. This method works fine with the 98mm Aeropack retainer
 

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You can nest Aeropack adapters 98 to 75 and 75 to 54. I've flown a L1000 DMS and a K700 in my 7.5" FG L3 project. No problems just get all the pieces in the right place. That gives maximum flexibility for that M2500 you'll want to fly later. This method works fine with the 98mm Aeropack retainer
Ken, that's great news - simplifies my setup a lot. Would you happen to have a picture of a 54 mm nested in a 98 mm motor mount tube? I'm having trouble picturing how the two adapter systems fit together.
 

KenC

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Unfortunately I am not at home for the next couple weeks. So no photos. I will attempt to describe the process.

The adapters come with three pieces each. A compression centering ring that clamps to the motor case (or the smaller compression ring, for 98 to 54mm) The other pieces are a thrust ring and a retention ring. The thrust ring(s) are installed first, to transfer force to the 98mm screw retainer from the smaller diameter motor case. The thrust rings are the same outside diameter as the relevent motor thrust ring. The retainer ring(s) fit behind the motor case and under the 98mm retainer nut to keep the motor case attached to the rocket.

Installation sequence:
1.Place 54 to 75mm thrust ring on motor case.
2.Place 98 to 75mm thrust ring on above adapter thrust ring
3.Install 54 to 75mm compression centering ring 2" from front of motor
4.Install 75 to 98 mm compression centering ring on top of the above ring
5. Insert above assembly into Aeropack retainer and assure thrust rings are aligned and centered in the 98 mm retainer
6. Place both retainer rings over motor and align and center
7.Screw on the 98mm threaded retainer nut and fly.

Much easier to do than explain. Watch for used adapters on the yard sale or on e-bay. The adapters are quite reasonable when purchased new too.
 

jmuck78

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Unfortunately I am not at home for the next couple weeks. So no photos. I will attempt to describe the process.

The adapters come with three pieces each. A compression centering ring that clamps to the motor case (or the smaller compression ring, for 98 to 54mm) The other pieces are a thrust ring and a retention ring. The thrust ring(s) are installed first, to transfer force to the 98mm screw retainer from the smaller diameter motor case. The thrust rings are the same outside diameter as the relevent motor thrust ring. The retainer ring(s) fit behind the motor case and under the 98mm retainer nut to keep the motor case attached to the rocket.

Installation sequence:
1.Place 54 to 75mm thrust ring on motor case.
2.Place 98 to 75mm thrust ring on above adapter thrust ring
3.Install 54 to 75mm compression centering ring 2" from front of motor
4.Install 75 to 98 mm compression centering ring on top of the above ring
5. Insert above assembly into Aeropack retainer and assure thrust rings are aligned and centered in the 98 mm retainer
6. Place both retainer rings over motor and align and center
7.Screw on the 98mm threaded retainer nut and fly.

Much easier to do than explain. Watch for used adapters on the yard sale or on e-bay. The adapters are quite reasonable when purchased new too.
Ken, thanks for the explanation. I have successfully nested the adapters all the way up to the 75 mm size. The part that seemed infeasible was installing the 98mm compression centering ring on top of the 75mm centering ring. Since the rings don't have a large width, it seemed that these might be prone to slipping during launch, but if it works, then I will restrain my skepticism. Thanks again for the response.
 

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I make cheap adapters for rockets with wood centering rings. Much less expensive than Aeropak adapters in the event of a cato.

You will need:
about 12" of 54 mm motor tube
2 98-54 centering rings
1 5.5 or 6" -54 centering ring

Epoxy 6" CR to end of tube. Epoxy 1 98 CR against the 6" CR. Make sure the shoulder between the 2 CRs is clean, must fit into 98 mm motor tube. Epoxy the other 98 mm CR near the front of the motor tube. Drill 4 screw clearance holes outside the 98 mm tube diameter in the 6" CR. To use, slide 54 mm motor into adapter all the way to thrust ring. Wrap a few layers of masking tape around the motor just in front of the 54mm tube to keep the motor from falling out. Slide adapter into rocket's 98mm mount and use wood screws to hold in place.

I usually double the rear CR in the rocket so there's more for the wood screws to bite into. You can make a 75-98 adapter the same way changing all 54mm to 3" above.
 

jmuck78

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Sorry for the black out, I was waiting for some replacement centering rings from LOC - I received the kit without the fin loc centering rings, and of course Jason @ LOC was more than helpful in sending out the replacements. Those guys are really top notch with supporting their products. In the mean time, I have beveled the fins and now attached the first two centering rings to the 98 mm motor tube. I'll update the sections above in the next day or so.
 
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jmuck78

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I updated post #2 with the motor mount progress to date. Because of the complexity of the booster/tailcone/motor-mount, the rest of the centering ring installation will probably be covered in posts 3 and 4. The current plan is to epoxy the motor mount tube w/ coupler into the booster section, attach the second booster tube, and then fiberglass the booster, but I need to think through the order of operations first.
 
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jmuck78

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Installed the motor assembly into the booster section and joined the two booster sections (see post #4). I made a mistake by installing the upper booster section to the lower without first installing the harness. My arm is not long enough to reach the U Bolts to attach the quicklinks (which is what I had planned to do), so I had to remove the upper tube and tie on a Kevlar strap left over from my Wildman Extreme build.
 

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looks like a great build so far

kudos on the quick thinking to break the tubes a part to attach the Kevlar before the epoxy set. no doubt ive "been there" before. assembling away only to realize that you've assembled yourself right into a corner...
 

jmuck78

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Updated post #3 with the Nose Cone Reusable Nose Weight System. I had already completed this step before I decided to do the build thread, so I described the process with photos of the completed but disassembled nose cone.

I also started fiberglassing the booster section, but I ran out of laminating epoxy about 60% of the way through. I was able to complete just above the joint between the two booster tubes and then all the way aft. I need to reopen the fin slots, but once I do that I may go ahead and install the fins with the forward section incompletely fiberglassed and then just apply the laminating resin after the fins are done.
 

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How are you able to update your posts? I haven't been able to past a day or so since the forum transferred to the new format
 

jmuck78

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I installed the fins and started adding the fillets (see post #7). The first fin was (embarrassingly) out of a alignment which was bound to happen since i don’t have a fin alignment guide big enough for this body diameter. I tried to pop it off, but no luck, so i’ll have to live with it. Rest of the fins seem to have gone on well.
 
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jmuck78

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I added the next round of internal / external fin fillets. This round was messy and less satisfying. The fins are gapped at the forward end either due to the plywood warping or being installed at a slight angle (probably due to the extra thickness of the fiberglass layer imparting a slight angle over the 4 foot length of the fins). I'll post pictures of the complication later, but I *think* the gap is fillable with epoxy as long as I have nice, large external fillets on the fins. I also added a second internal fillet where the forward fin tab enters the forward fin slot. I'm going to end up spending the rest of the winter sanding these fillets, though...
 

jmuck78

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Update: I have completed all of the internal and external fin fillets, installed the aft loc-n-ring centering ring and the tail cone subassembly. I still need to install the motor retention hardware on the final, smaller centering ring, epoxy it in place, and epoxy the tail cone shut.
 
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