**E178 Weasel Basic Assembly Instructions** |[home](index.md.html)|[syllabus](syllabus.md.html)|[assignments](assignments.md.html)|[labs](labs.md.html)|[final project](finalproject.md.html)|[flight data](FlightData.md.html)|[getting certified](RocketryCertification.md.html)| # Safety Notes * Always use a lab coat (if available), nitrile gloves, and safety glasses when using epoxy. Repeated contact of epoxy with skin leads to very serious allergic reactions. * On the academic side of campus, all adhesives (except white or carpenter's glue) need to be used in a fume hood, a spray-paint booth, or outdoors away from any air inlets to buildings. * At home or in the dorms ensure adequate ventilation when using epoxy. * Glass microspheres are an inhalation hazard. Use extreme caution and use a face mask if possible. * If you use spray paint, be sure to use adequate ventilation, nitrile gloves, a face mask, and safety glasses. # Notes on Epoxying !!! Warning For the Weasel, use **only** the 5 minute epoxy for every joint **except** for joining the motor retainer to the motor mount tube. For that joint use **only** JB Weld. - The following steps make for good epoxy joints: 1. Sand every surface to be epoxied (including interior surfaces) with 80-to-110 grit sandpaper. 2. Clean the surface with a lint-free cloth or Swiffer. 3. For fiberglass, metals, or pastics, wipe the surface down with acetone or isopropyl alcohol and let dry before using the epoxy. Not necessary for cardboard, plywood, or paper - Protect any exterior surface where you _don't_ want scratches or sanding marks with blue or masking tape before you begin sanding. - You can make the epoxy thicker and lighter (with a small decrease in strength) by mixing in glass or silica microspheres. A 1:1 volume ratio of microspheres to epoxy usually works well. You could use 1:2 or 2:1 if you wanted. This mixture works well for fillets that don't need to support large loads. - You can make the epoxy thicker and stiffer by mixing in chopped glass fibers. A 1:1 volume ratio of fibers to epoxy usually works well. If you want a smoother finish, use 1:2 or 1:3. - Epoxy cures to a much higher strength if the joint is heated by a heat lamp or placed inside a heater while it cures. Do not let the joint heat above 140 °F (60 °C). # General Construction Tips - Always dry fit parts before applying epoxy, and sand if necessary so that they fit properly. - When sliding circular parts together, hold them so that the epoxy forms a fillet and doesn't pool or drip off. The required orientation is usually vertical. - If you slide two parts together, the epoxy will always be pushed forward off of the part on which the epoxy was applied. e.g, if you are epoxying a coupler to the inside of a body tube, the excess epoxy will be on the inside of the body tube if you apply the epoxy to the inside of the body tube, and on the outside of the body tube if you apply the epoxy to the outside of the coupler. - Twisting circular parts while pushing them together will spread the epoxy more evenly in the joint. - There is a student-written [TLDR](DX3AssemblyTLDR.md.html) talking about hints when following the instruction. It was written for the MiniDX3, but still applies largely to the Weasel. - There is a detailed student-written [blog](DX3AssemblyBlog.md.html) on putting the rocket together. It was written for the MiniDX3, but still applies largely to the Weasel. # Parts The image below displays almost all of the parts that come in the kit. There are several of these you will not use in assembling your Weasel. ![Figure [DPL]: The parts that come in the kit](Images/Wea_Kit_Parts.png) The following is a list of additional parts you need to assemble your rocket. - An Estes 29mm motor retainer - Three #2-56 x 3/16" pan-head screws - Two ACME conformal rail guides - A #10 black oxide eyebolt - Two #10 black oxide washers - Two #10 black oxide nuts - Two or three fin guides - A 6x6 Chute protector - A 12-foot length of 1/8" Kevlar shock cord - A curing stand and bulkhead spacer (See Figure [CSR]) ![Figure [SPL]: Additional Parts for Weasel](Images/Wea_Addl_Parts.png width="400px") You will also need a ruler, a pencil, 5 minute epoxy, 80-to-110 grit sandpaper, emory board, masking (blue) tape, nitrile gloves, mixing cups, stir sticks, drill bits, #2-56 tap, a wood dowel, and an x-acto knife or saw. # First Step Sand every surface to be epoxied (including interior surfaces) with 80-to-110 grit sandpaper. You may have to think about the assembly sequence to figure out where to sand. Don't forget about the inside of the Estes motor retainer. Pretty much the entire exterior of the motor mount should be sanded or roughed up. # Motor Mount Assembly ![Figure [MMP]: The Motor Mount, Centering Rings and Motor Retainer](Images/Wea_MotorTube_Rings_Retainer.png) - Test fit centering rings over the motor mount tube and sand centering rings if necessary. - Also test fit the centering rings in the body tube and sand the rings if necessary. - Place the inside part of your Estes motor retainer on one end of the motor mount tube. Make sure it is fully seated. Using a pen or pencil, mark the tube where the motor retainer hits the tube. ![Figure [MMM]: Mark the Motor Mount for the motor retainier.](Images/Wea_Mark_Retainer.png) - Screw on the outside of the motor retainer. - Insert the assembly into the slotted end of the rocket body tube so that the motor tube is still seated in the retainer and the outside of the retainer is resting against the body tube. - Use a sharpened pencil or other marking implement that will reach and mark the location of the bottom of the bottom slot, and the top of the top slot on the motor mount tube. ![Figure [MMR]: Mark the Motor Mount for the motor retainier.](Images/Wea_Motor_Mount_Mark_Fin.png) - Remove the assembly and connect the marks to create two circles around the motor mount tube. If a centering ring will fit over the tube, you can use it as a guide for your circles. The space between the circles is where the fins will contact the motor mount tube and needs to be kept clear of epoxy or other materials while assembling the rocket before attaching the fins. The space between the ring for the top of the retainer and the bottom of the fins is where the bottom centering ring may be epoxied in place. it's usually to mount the bottom centering ring directly on the top of the motor retainer. !!! note The strength of the bond between the fins and the motor mount can be greatly increased by putting internal fillets between the fins and motor mount tube, and the fins and the body tube. That strength is not needed for motors with 180 Ns of impulse and below, but should be considered if going above 180 Ns, and is required in the Vulcanite and the class 54mm fiberglass rocket. The next step makes creating internal fillets very difficult. - Using JB-Weld (_not any other epoxy_) attach the inner part of the motor retainer to the bottom of the motor mount assembly. Spread the JB-Weld on the motor mount tube and _not_ inside the motor retainer. Twist the motor retainer as you push it onto the tube. - Inspect the inside of the motor mount tube-motor retainer and thoroughly wipe away any JB-Weld that made it inside. - Slide the bottom ring (_without_ the notch) down the motor mount tube and twist it into the JB-Weld on top of the motor retainer until it is resting on the motor retainer. - Place the assembly vertically (resting on the motor retainer), and let cure for at least 3 hours, preferably in a warm space. JB-Weld takes 24-48 hours to fully cure, but will usually not run after 3 hours. - Place a fillet of epoxy along the top surface of the bottom centering ring and try hard to keep the epoxy from getting on the side of the centering ring or the threads of the motor retainer. ![Figure [MMB]: The Motor Mount with the Motor Retainer and the Bottom Centering Ring JB-Welded in place](Images/Wea_Retainer_Bottom_Ring.png) ## Shock Cord !!! Note You have your choice of using the nylon and Kevlar shock cords that came with the kit, or using a 12-foot length of 1/8" Kevlar shock cord. The instructions assume you will use the 12-foot length of Kevlar. - The placement of the top ring (the one with the notch) isn't critical: It should be above the top of the fin mark, but no closer than 1/4" from the end of the tube. Usually about 1/2" for the top of the tube is about right. You need to trap a length of the shock cord under the top centering ring. Place the shock cord through the centering ring, then run the shock cord along the motor mount tube, align one of the notches with the shock cord, and slide the centering ring over the shock cord and motor mount tube as shown in Figure [TRK]. ![Figure [TRK]: The Top Centering Ring and Shock Cord in position prior to being epoxied into place](Images/Wea_Retainer_Top_Ring_Kevlar.png) - Spread some epoxy on the outside of the motor tube at your chosen location and slide the top ring (_with_ the notch) up the tube until it is in position (which should create a top-surface fillet), and wait for the epoxy to set. Be sure to clean off any epoxy that strayed into the fin or motor retainer zones. ![Figure [RF2]: The Top Centering Ring after the top fillet, but before the Shock Cord has been secured with epoxy](Images/Wea_Motor_Tube_Top_Ring_Fillet_2.png width="250px") ![Figure [RF1]: Another view of the Top Fillet on the Upper Centering Ring. The Shock Cord has not yet been epoxied in place.](Images/Wea_Motor_Tube_Top_Ring_Fillet_1.png width="250px") - Apply some epoxy like a fillet between the lower side of the top centering ring and the motor mount and wrap the Kevlar end of the shock cord around the motor mount into the epoxy. Make sure the cord lays flat enough so it will not interfere with the body tube when you slide the motor tube inside. Make sure the cord is secure and will not come loose later with ejection forces that will pull on the shock cord. See Figure [MKE]. ![Figure [MKE]: The completed Motor Mount Assembly with the Shock Cord epoxied in place](Images/Wea_Motor_Tube_Kevlar_Epoxied.png) # Forward Section - Drill a hole through the Bulkhead for either threading a #10 screw or close clearance of a #10 screw. - Thread a nut all of the way to the eye on the eyebolt, then place a washer on the eyebolt. ![Figure [EBW]: The Eyebolt with the first nut and washer](Images/Wea_Eyebolt.png width="250px") - Insert the eyebolt through the hole in the center of the bulkhead and secure using an additional washer and nut. !!! WARNING Apply some thread lock, epoxy, or CA to the nut and eyebolt threads to ensure the nut doesn’t come loose later. ![Figure [EB]: The Eyebolt, Washers, and Nuts in position on the Bulkhead. The dark streaks are due to the thread-locking compound.](Images/Wea_Eyebolt_Bulkhead.png width="250px") - Cut off the eyebolt (Dremel or hacksaw) leaving about 1/4"-to-1/8" above the nut and file or sand the end to remove any sharp edges. !!! Warning The eyebolt and the cut-off piece may be very hot (burn hazard) while and after you cut the eyebolt. ![Figure [ET]: The Bulkhead with the top of the eyebolt after being cut and rounded](Images/Wea_Eyebolt_Trim.png width="250px") !!! note You will need the coupler tube for the following steps. It may be hidden inside either the payload tube or the body tube. If so, reach inside and slide it out. - Mark a line around the inside of the coupler tube 1/8" from the end. - Assemble the Curing Stand with the Small Spacer Ring centered on the top of the stand. ![Figure [CSR]: The Coupler Curing Stand and the Small (Weasel) Ring](Images/Curing_Stand_Small_Ring.png width="250px") ![Figure [CSS]: The Coupler Curing Stand with the Small (Weasel) Ring in position](Images/Curing_Stand_Small_On_Top.png width="250px") - Apply epoxy to the inside of the tube and push the bulkhead in so that the line is visible. Set the assembly on the stand with the eyebolt through the holes in the Small Spacer Ring and Curing Stand. The purpose of the Spacer Ring is to maintain the 1/8" spacing until the epoxy cures. Try to keep any epoxy from getting on the spacer or stand. ![Figure [CBE]: The Coupler, Bulkhead, and Eyebolt in curing position atop the Curing Stand](Images/Wea_Stand_Coupler.png width="350px") - Apply a fillet of epoxy around the inside edge of the coupler bulkhead joint. ![Figure [NF3]: A bottom view of the Coupler/Bulkhead fillet](Images/Wea_NC_Fillet_3.png width="350px") ![Figure [NF2]: A side view of the Coupler/Bulkhead fillet](Images/Wea_NC_Fillet_2.png width="350px") - Mark a line around the coupler 2 1/2" (halfway) from the open end. ![Figure [CH]: The Coupler Tube marked at the halfway point](Images/Wea_Coupler_Half.png) - Apply a very thin amount of epoxy on the first inch to two inches of the outside of the coupler, and twist and slide the coupler into the payload tube (forward body tube) until you reach the halfway mark. Quickly wipe off any excess epoxy at the payload tube-coupler joint. The payload tube will not join properly with the body tube if you leave excess epoxy at the joint. ![Figure [CE]: The Coupler Tube with epoxy spread on the upper half. Leaving about 3/4" above the line unspread was intentional.](Images/Wea_Coupler_Epoxy.png) ![Figure [CP]: The Coupler Tube epoxied half way into the Payload Tube](Images/Wea_Coupler_Payload.png) - Measure down 1 1/2" from the shoulder of the nose cone, and using an X-acto knife or a saw, cut off the bottom of the nose cone, and if necessary, sand the cut square. It will be pressing against the avionics carrier and should be as square as possible. ![Figure [NT2]: The Nose Cone after being cut 1 1/2" down from the shoulder](Images/Wea_Nose_Cone_Trim_2.png) - Insert the nose cone into the top of the payload tube. ![Figure [CPN]: The Coupler Tube, Payload Tube, and Nose Cone ready for marking and drilling](Images/Wea_Coupler_Payload_NC.png) - _Holes for Payload – Nose Cone Screws_: Mark three points equally spaced around the circumference of the payload tube 3/4" down from the top of the Payload Tube. Create a Marking Guide by wrapping a piece of paper around the tube and marking the circumference. Unwrap and measure the circumference and divide the distance by three and mark the paper accordingly. ![Figure [DGM]: The Marking Guide with the marking locations every 1/3 of the circumference](Images/Wea_Drill_Guide_Marked.png width="400px") - Transfer the marks to the payload tube by wrapping the paper back around the tube and marking. ![Figure [DPM]: Marking the Payload Tube with the Marking Guide](Images/Wea_Drill_Position_Marked.png width="250px") - _Holes for Altimeter Vents_: Repeat the marking procedure 1 1/4" above the coupler-payload tube edge. ![Figure [PDM]: The Payload Tube marked for drilling](Images/Wea_Payload_Drill_Marked.png) - Drill all six holes with a #52, #51, or #50 bit. Drill slowly to try to leave the inside edges of the holes as clean as possible. _You might consider drilling, tapping, and putting in a screw for the first hole before drilling the other five, to avoid the tube and nose cone rotating relative to each other._ - Tap the top three holes with a #2-56 tap. These will secure the nose cone to the payload section. - Screw a pan-head #2-56 screw into each threaded hole. These will hold the nose cone on during flight, but permit it to be removed to access the avionics. - The other three holes are to permit the altimeter to measure the free-stream pressure outside the rocket for calculating the altitude. - If you are going to install an avionics carrier, you will want to put a layer of foam in the bottom of the payload section. ![Figure [NCDS]: The Coupler Tube, Payload Tube, and Nose Cone after marking, drilling, tapping and insertion of #2 pan-head screws](Images/Wea_NC_Payload_Drilled_Screwed.png) # Final Assembly The final assembly involves epoxying in the motor-mount assembly, attaching and filleting the fins, attaching the launch lugs, and attaching the chute protector, the parachute and the payload section. ## Inserting the Motor Mount Assembly - Hold the motor mount assembly by the body tube at the position that it will be when epoxied in. Measure how far up the body tube the front centering ring will be. - Using sandpaper attached to the end of a dowel, roughen up the inside of the body tube where the front centering ring will be attached. ![Figure [TSR]: The Sanding Rod for Top Centering Ring.](Images/DX3_SandingRod.png) - Put the shock cord inside of the motor mount tube so it's out of the way while the motor mount assembly is epoxied in. - Screw the outside of the motor retainer onto the end of the motor mount assembly. - Use one or more craft (popsicle) sticks taped together to create a glue spreading stick for the upper centering ring. ![Figure [PES]: A Glue Spreading Stick marked with the insertion depth for the Upper Centering Ring](Images/Wea_Motor_Tube_Position_Epoxy_Stick.png) !!! WARNING The next several steps need to be completed quickly, before a batch of epoxy has time to set. - Using your glue spreading stick, place a ring of epoxy inside the body tube about 1/4" short of where the front centering ring will sit. You need to get the epoxy up the tube without dripping anywhere else in the tube. - Insert the motor mount assembly part-way up the body tube. - Put a ring of epoxy around the lower end of the body tube between the bottom end and the fin slots. - Push and twist the motor mount assembly into the body tube. Be sure the bottom ring doesn't extend into the fin slots. - Make sure the rocket is vertical until the epoxy cures. !!! Note You may consider cutting a ring out of parchment paper and putting it over the motor retainer so that dripping epoxy doesn't permanently bond the outer motor retainer ring to the rocket. ## Launch Lug Marking For maximum versatility in launching, it's best to install both the set of two aluminum launch lugs designed for launch rails and the cardboard launch lug designed for 1/4" launch rods. It's easiest to mark the body tube for the launch lugs before putting on the fins. - Remove the outer ring of the motor retainer. - Place a length of angle iron so that one edge is halfway between a set of two fin slots, and draw a vertical line up the body tube. - Repeat between another set of two fin slots. !!! Note **Do NOT** attach the rail guides or launch lugs at this time! You will attach them **after** you finish the fin fillets. You are marking the lines at this time because it's much harder to do after the fins are in place. ## Fins - Dry fit the fins and if necessary sand the slots until the fins fit. You have to be able to place them quickly, but you don't want them to be a loose fit. - Make sure you have two or three fin jigs handy. !!! WARNING The next several steps need to be completed quickly, before a batch of epoxy has time to set. - Apply a generous-but-not-overflowing amount of epoxy to the root end of each fin tang and insert it into the fin slots. - Before the epoxy sets, place a fin jig on each side of the fins and place the assembly on a table to guarantee the fins are straight. A third jig at the end of the body tube will help you keep things level - Before proceeding, make sure the epoxy has fully cured. ![Figure [FG2]: The Fins being held in position by the Fin Guides during epoxy cure (View 1)](Images/Wea_Fin_Guides_2.png) ![Figure [FG1]: The Fins being held in position by the Fin Guides during epoxy cure (View 2)](Images/Wea_Fin_Guides_1.png) ## Fin Fillets - Get a set of plastic spoons that will be used for pulling the fillets. - Rub the edges of the spoon heavily with a pencil lead, a pen, or a permanent marker. - Draw the spoon along the joint between the fin and the body tube. With luck, you'll see a line where the spoon met the fin and where it met the body tube. - Place blue tape along each line. - Repeat the marking and taping for each of the remaining fin-body-tube joints. - Place blue tape at the top and bottom of the fin/body tube where you want the fillet to end. - If you haven't already sanded the body tube and the fins where the filets will go, do so now. Depending on how vigorous you are on the sanding, you may or may not need to retape the fins and body tube after sanding. ![Figure [TFF]: The location for the Fin Fillets after taping and sanding](Images/Wea_Taped_for_Fillets.png) - Because 5 miute epoxy cures so rapidly, plan on mixing and applying one batch for each fillet, but doing two fillets sequentially between adjacent fins and then letting the epoxy cure completely before doing the next batch of two fillets - Measure out a batch of glass microballoons equal in volume to the batch of epoxy you are about to mix. Doing about a 3-second firm squeeze of each epoxy component mixed with 1/2 tsp of microballoons works well for each fillet batch. - Mix a batch of epoxy (stir for 30 s) and quickly fold in the microballoons (and stir for 30 s). It should have roughly the consistency of peanut butter. - Lay the epoxy down in the joint and roughly smooth it with the stir stick. - Using a plastic spoon, pull along the fillet, leaving a nice concave profile, with excess epoxy being gathered up by the spoon. - Quickly touch up any flaws. - Remove the blue tape along that particular fillet. - Repeat the procedure for the other fillet in this batch - Let them fully cure before moving on to the next fillets. ![Figure [FF]: A side view of the finished Fin Fillets](Images/Wea_Finished_Fillets.png) ![Figure [FEV]: A rear view of the finished Fin Fillets](Images/Wea_Fillets_End_view.png) ## Launch Lugs !!! Warning Sand the body tube where it is going to join the launch lug until you have removed the glassine (the shiny paper layer). Also sand the launch lugs. Failure to do so may result in moments of panic at the launch stand when your launch lugs break off. - Place the upper launch lug about 6" below the top of the body tube and centered on the launch lug line. Trace around the launch lug. ![Figure [ULP]: The location for the Upper Launch Lug penciled in position](Images/Wea_Upper_Launch_Lug_Position.png width="400px") - Place the lower launch lug in line with the upper launch lug position roughly centered between the top and bottom of the fins and centered on the launch lug line. Trace around the launch lug. ![Figure [BLP]: The location for the Lower Launch Lug penciled in position](Images/Wea_Bottom_Lug_Position.png) - Place blue tape about 1/16" to 1/8" outside of the launch lug traces. - If you have not yet done so, sand the areas where the launch lugs will be epoxied. Depending on how vigorously you sand, you may or may not need to retape the outlines and retrace the centering line. ![Figure [ULTS]: The location for the Upper Launch Lug after taping and sanding](Images/Wea_Upp_Launch_Lug_Taped_Sanded.png) ![Figure [LLTS]: The location for the Lower Launch Lug after taping and sanding](Images/Wea_Low_Launch_Lug_Taped_Sanded.png) - If you have not done so yet, sand the underside of the launch lugs. Sand principally crosswise, not lengthwise. ![Figure [LLS]: The underside of the Launch Lugs after sanding with 80-git sandpaper](Images/Wea_Launch_Lugs_underside_sanded.png width="250px") - Epoxy the launch lugs in place by putting epoxy on the underside, placing the launch lugs in position and wiggling them slightly while pressing down to create small fillets around them. - Remove the blue tape to leave relatively sharp edges to the fillets. !!! WARNING You may need to hold the launch lugs in position until the epoxy cures to keep them centered on the line. ![Figure [ULE]: The Upper Launch Lug epoxied in place](Images/Wea_Upp_Launch_Lug_Epoxied.png) ![Figure [LLE]: The Lower Launch Lug epoxied in place](Images/Wea_Low_Launch_Lug_Epoxied.png) - Place the cardboard launch lug on the remaining launch lug line about 1" above the top of the fins. Trace a line at the top and bottom of the launch lug. - If you haven't already done so, sand the body tube along the launch lug line between the top and bottom marks. - If you haven't already done so, sand along the bottom of the launch lug where you plan on having it attach to the body tube. - Place a generous amount of epoxy along either the sanded part of the body tube or the sanded part of the launch lug. Position the launch lug alnog the body tube and hold it in place until the epoxy cures. ![Figure [FV]: The Attached Launch Lug for the 1/4" Rod top view](Images/Wea_Lug_For_Rod_Top_View.png) ![Figure [FV]: The Attached Launch Lug for the 1/4" Rod side view](Images/Wea_Lug_For_Rod_Side_View.png) ## Chute Protector and Parachute - Shake or push the shock cord free out the top of the body tube. - Thread the chute protector through the shock cord and slide down to the body. - Roughly 2/3 of the shock cord length (the length from the body tube up) tie a [butterfly knot](https://www.101knots.com/butterfly-knot.html) or a [figure eight knot on a bight](https://www.101knots.com/figure-8-on-a-bight.html). - Attach the end of the shock cord to the eyebolt in the payload section with a [PML knot](https://cdn.shopify.com/s/files/1/0588/8370/2933/files/Phobosinstructionbooklet.pdf?v=1630062404) (Step 9 on Page 6) and secure the end to the standing part of the shock cord with either electrical or blue tape rather than epoxy. - Attach the parachute to the butterfly knot or the figure eight knot on a bight with a Lark's Head knot. Gather the shroud-line loops. Push them through the bight on the shock cord. Pass the parachute through the shroud-line loops and pull. See Step 3 under Prepare Recovery System (page 5) of the [Estes Alpha Instructions](https://estesrockets.com/wp-content/uploads/Instructions/001225.pdf) if it's unclear. ### Folding the Chute If you want to fold the parachute and pack it in the rocket use the [Instructions for Folding Parachutes](ParachuteFolding.md.html) ## Painting and Marking If you desire to paint your rocket, please do so. There are lots of places on-line that will give you an overabundance of advice on how to do so. Many fliers prefer to make their rocket "earn it's paint" by flying it unpainted, and then painting it if it survives the first flight. - You should mark the center of pressure with a center-of-pressure symbol, which is a circle with a dot in the middle, $\odot$. A Sharpie® works great, but we do have water-slide decals if you want to get fancy. - Label the rocket with your name and cell-phone number on both the body tube and payload section. Again a Sharpie® works great, but you can use print-on adhesive labels or Sam's labeling machine as well. ## The Avionics Support Instructions for cutting or modifying the plywood parts for the Avionics Support are found [here](SolidWorks/Weasel/CuttingTheWeaselAvionicsBayParts.md.html) The avionics support is where you will mount your GPS tracker, your Teensy IMU/data logger, and the two batteries for them. The eight parts are shown from the front side in Figure [WFS] and from the back side in Figure [WBS]. Be sure you can identify which side is which. The front side is the side that faces the laser during cutting and shows little if any charring from the cutting laser. The back side is the side on the metal grill away from the laser and has multiple char marks from where the laser reflects off the grill. All of the pieces are directional and it is easy to inadvertently assemble the pieces in a way that will not work, and you will have to laser cut new parts and reassembly a new holder correctly. ![Figure [WFS]: The Front Side of the laser-cut parts for the Avionics Support](Images/Wea_EbayTopSurface.png) ![Figure [WBS]: The Back Side of the laser-cut parts for the Avionics Support](Images/Wea_EbayBackSurface.png) - If desired, sand a slight bevel on the outward facing tabs of the Main Support to make assembly of the Side Supports easier. The tabs already have a slight chamfer on them. - Dry fit the rings. If necessary (not likely) sand them to fit better. - Start a dry fit of the Lower and Upper Side Supports on the Main Support to see if they will start. Sand as needed. Do **not** push them all of the way on. You will probably not be able to get them off if you do. - With everything disassembled after the test dry fit, identify the Middle Centering Ring, the one with the single rectangular slot. face it so that the top side is facing upwards. Starting at the top (the end with the off-center cut) of the Main Support, slide the Middle Centering Ring over the Main Support with the top surface of the centering ring facing upwards and the large part of the loop on the front of the Main support. There are two tabs about 1/3 of the way down the Main Support on which the ring will rest. Place white glue on the top surfaces of the tabs and lines of white glue on the front and back of the Main Support where the Middle Centering Ring will rest, and then slide the ring into position. - Before the glue dries, align the Upper Side Supports so that the back sides are facing towards the tabs of the Main Support. Place white glue on the edges of the Main Support between the tabs above the Middle Centering Ring and then press the Upper Side Supports into position. They should lock the Middle Centering Ring in place so that it is perpendicular to the Main Support. If you can't slide them all of the way on by hand, using a vice to squeeze the side supports in place should work. When finished, the Upper Side Supports should be normal to the Main Support with the front sides facing outwards. - Align the Lower Side Supports so that the back sides are facing towards the tabs of the Main Support and the forked ends are pointing upwards. Place white glue on the edges of the Main Support between the tabs below the Middle Centering Ring and then press the Lower Side Supports into position. If you can't slide them all of the way on by hand, using a vice to squeeze sections of the side supports in place should work. When finished, the Lower Side Supports should be normal to the Main Support with the front sides facing outwards. ![Figure [WMCR]: A Back View of the Main Support with the Middle Centering Ring and Side Supports Attached](Images/Wea_EbayCenterRingSideSupports.png) ![Figure [WACRS]: A Side View of the Main Support with the Middle Centering Ring and Side Supports Attached](Images/Wea_CenterRingSideSupportsSideView.png) - Place the Lower Centering Ring (the one with the symmetric circle extending from the horizontal slot) on a piece of parchment paper with the top surface facing upwards, and the larger sied facing forwards. - Place white glue around the bottom of the Main Support and place it in the slot in the Lower Centering Ring so that the large side aligns with the large side of the Middle Centering Ring. - Find some means, such as 1-2-3 blocks to support the Main Support so that it is normal to the Lower Centering Ring until the glue dries. - Find the Top Centering Ring (the one with the offset hole extending from the horizontal slot) and face it so the top surface is upwards and the larger part of the loop aligns with the larger parts of the loops on the other two rings. Place white glue around the top of the Main Support and place the Top Centering Ring on it. - Find some means, such as 1-2-3 blocks to support the Main Support and the Upper Centering Ring so that they are normal to each other until the glue dries. ![Figure [WACR]: A Front View of the Main Support with all Centering Rings and Side Supports Attached](Images/Wea_EbayAllRings.png) ## Avionics Installation The avionics that need to be installed are: - [A Featherweight GPS Tracker](https://www.featherweightaltimeters.com/featherweight-gps-tracker.html) - Two 400 mAh 1S LiPo batteries. The photos show the flat LiPo's, but the rounded ones will fit better. However, either type will work. - A Small Teensy Data Logger. - The teensy data logger power switch. The avionics are placed as shown in Figure [WFA] through Figure [WFL]. Detailed instructions follow. ![Figure [WFA]: The Front Side of the Avionics Support with avionics installed](Images/Wea_ABTop.png) ![Figure [WFR]: The Right Side of the Avionics Support with avionics installed](Images/Wea_ABSideOne.png) ![Figure [WFB]: The Back Side of the Avionics Support with avionics installed](Images/Wea_ABBottom.png) ![Figure [WFL]: The Left Side of the Avionics Support with avionics installed](Images/Wea_SideTwo.png) - To keep the Teensy Data Logger from transmitting spurious signals to the GPS, cover the top surface of the Middle Centering Ring with aluminum tape as shown in Figure [WTF] and Figure [WTB]. ![Figure [WTF]: The Top Side of the Middle Centering Ring covered with Aluminum Tape (front view)](Images/Wea_AVAddFoil.png) ![Figure [WTB]: The Top Side of the Middle Centering Ring covered with Aluminum Tape (back view)](Images/Wea_AddFoilBack.png) - If the Featherweight GPS does not alrady have a JST PH battery connector, trim the leads on a JST PH battery connector to the desired length, strip and tin the ends, and attach them to the screw terminal on the GPS. Besure to observe polarity, red to + and black to –. - Attach the GPS to the top front of the Avionics Support with #4-40 screws, 1/8" nylon standoffs, and #4-40 nuts. It is sometimes easier to remove the antenna, install the GPS, and then reinstall the antenna, rather than install the GPS with the antenna attached. - Cut Velcro strips to fit through the slots and wrap around a LiPo. - Install the LiPo and secure it with the Velcro strips. The switch on the GPS controls the power to the GPS. A small screwdriver or similar implement makes it easier to flip the switch. - Install a slide switch with M2 screws and M2 nuts onto the top surface of the Avionics Support. - The switch connects to the Small Teensy Logger through a female Molex connector that plugs into the male Molex connector on the Teensy Logger near the power connector location. Cut and strip the leads on a female Molex connector to the desired length, and solder them to the center and one of the side terminals on the back of the switch. Choose the side terminal that corresponds with how you want the switch positioned when the poser is on. Standard convention is for _on_ to be to the right, and _off_ to be to the left when viewed from the front. - If not already attached, connect a JST PH male connector to the power inputs on the Small Teensy Data Logger. Be sure to observe polarity, red to + and black to –. - It is not necessary to connect thermistors to the two bottom Molex connectors on the Teensy data logger, but if you are going to do so, now would be a good time. ![Figure [WAT]: Front View of the wire routing for the Teensy Logger](Images/Wea_ABAddTeensy.png) ![Figure [WATB]: Back View of the wire routing for the Teensy Logger](Images/Wea_ABAddTeensyBot.png) - Route the switch connector up through the smaller hole and connect it to the Molex connector on the Small Teensy Data Logger. See Figure [WATB] and Figure [WAT]. - Route the JST PH battery connector through the larger hole. See Figure [WAT]. - If using the thermistors, route them through the equal-sized holes towards the bottom of the Avionics Support. See Figure [WAT]. - Mount the Small Teensy Data Logger on the Avionics Support with #4-40 screws, nylon stand-offs, and #4-40 nuts. See Figure [WFA] through Figure [WFL] for detailed placement. - Cut Velcro strips to fit through the slots above the Teensy Logger and wrap around a LiPo. - Install the LiPo and secure it with the Velcro strips. # Testing the Avionics (To be added soon. Ask Prof. Spjut if you need instructions now.) ----