Updated: 20 JULY 2018
It is time to start working on my Tripoli Level Three rocket project. It is going to be a large rocket that will be powered by an “M” motor. I plan on launching the rocket at AIRFest in Argonia, Kansas this upcoming Labor Day weekend. The name of the rocket will be BOTC84. That represents “Best of the Corps” 1984. This post will document my BOTC84 rocket build.
The rocket will be constructed out of Blue Tube that is sold exclusively by AlwaysReadyRocketry. The nosecone is built by LOC Precision and has the Removable Nose Weight System. This will allow me to add a tracker to the nosecone.
The fins are G10 fiberglass. I designed them in OpenRocket and am having them fabricated by Public Missiles.
Part of the level 3 certification requirements is the creation of a design package. To design the rocket I used the OpenRocket software package. The image above was created with this package.
BOTC84 OpenRocket File (Remove the ‘.txt’ at the end of the file to run in OpenRocket)
Per the Tripoli website, I also have to create a document that includes the following information:
- A completely filled out Pre-Flight Data Capture form
- Drawings of the rocket showing airframe components, fins, bulkheads, recovery system components, payloads, etc. (OpenRocket)
- A parts listing that includes material descriptions, adhesive types, screw sizes gauges, thicknesses, etc.
- A simplified wiring diagram of the electronic recovery system that shows the major components.
- Pre-flight checklist describing: field assembly of the rocket, motor installation, recovery system preparation, launcher installation, system arming, etc.
I used Microsoft Word to create my document. Once completed, I sent the document and OpenRocket file to the two TAP reviewers that have graciously agreed to certify my package, rocket, and launch.
The BOTC84 Rocket Build
The LOC Precision Removable Nose Weight System requires more construction but the end results are worth it. If your rocket is unstable, this system will help you get the center-of-gravity farther forward. In the case of the BOTC84, the system will be used to house tracking electronics as the nosecone will be recovered under a separate parachute. Instructions can be downloaded here.
- [12JUL2018] The bulkheads and mounting tubes will be glued inside the nosecone using epoxy. The first step is to wash the nosecone inside and out with soap and warm water to remove any oils or mold release agents.
- [12JUL2018] Epoxy the end bulkhead on the mounting tube after determining the total length of the couplers that will be contained inside.
- I used a vice to drive the T-nuts into the bulkhead and epoxied the nuts into place.
- [12JUL2018] The bulkhead was then inserted into the nosecone and epoxied against the transition of the cone to the shoulder.
- [13JUL2018] After the bulkhead epoxy dried, the mounting tube was inserted into the hole in the bulkhead. The tube was epoxied to the end of the nosecone and a fillet of epoxy was placed around the mounting tube – bulkhead connection.
- This system was designed with the idea of adding weight to the nose with a canister that slides into the mounting tube. I am going to use this canister to hold a radio tracker. This tracker is needed as the nosecone will be recovered separately from the rocket. The canister will be built as per the instructions but instead of lead shot, the canister will be hollow to hold the tracker.
- [14JUL2018] The canister has two bulkheads. One bulkhead has a hole for the eye bolt that will be attached to the parachute tether and deployment bag. The nut was attached with loctite. It was then set with epoxy to make it permanent.
- [20JUL2018] The ends of the electronics bay consist of two bulkheads. One bulkhead has a diameter that matches the outside diameter of the coupler used for the bay. The other has a diameter that matches the inside diameter of the bay. Each assembly was epoxied together with slow-hardening epoxy with colloidal silicon added.
- [21JUL2018] I drew three 4-inch chords from the on the joined bulkheads. Drawing a perpendicular line from the middle of the chord toward the center of the bulkhead will reveal the center of the bulkhead. I punched a pilot hole at the center of each bulkhead.
- [21JUL2018] Drilled a 3/8-inch hole through the center of each bulkhead. Inserted a 3/8-inch forged eye bolt with a small washer on the body tube side of each bulkhead. Secured this bolt with a large diameter washer and nut. I used Loctite on the nut and set the nut with 30-minute epoxy.
Motor Mount and Fin Can
- [20JUL2018] The top centering ring of the motor mount has eye bolts that will attach to the lower recovery shock cord. Two holes were drilled in this ring and eye bolts, washers, and nuts where attached.
- [20JUL2018] Before epoxying these nuts, I fit the centering into the body tube and over the motor mount tube to ensure that the eye bolts will not hit either one.
- [20JUL2018] Tightened the nuts with Loctite in the threads. Once the Loctite dried, epoxied the nuts with 20-minute epoxy.
- [20JUL2018] Sanded the top 1 inch of the motor mount tube. Attached the top centering ring with 30 minute epoxy. Once this dried, applied a slow-hardening epoxy fillet on the top of centering ring around the motor mount tube.
- [21JUL2018] Flip the motor mount over and set it on the nosecone to keep it horizontal. Applied another colloidal silicon slow-curing epoxy fillet to the centering ring/motor mount joint.
To Be Continued…..