Water rocket continued Umbrella type

Description

This is na new design of water driven rocket with an umbrella type parachute. The launcher and fin and nozzle parts are existing and a bit improved. For the launcher and the “motor” (= nozzle and adapter) you can find additional info here: https://www.printables.com/model/46571-water-rocket-and-launcher-platform-complete-instru These parts have been proven to be working (see old video). The files and instructions for those parts are duplicated and adapted down here. I will upload a new video when I have tested the design together with my grandchildren. https://youtu.be/JNP6PwhbNHg The idea is that the the air pressure pushes out water in the rocket and so providing upward thrust. The rocket is designed that it should stay vertically as much as possible, even at the top of the flight path, and falls back with the fins down (This is of course depending on the launch angle, center of weight and center of attack). When falling down, the “umbrella” should open and function as a parachute. In the previous tests (see movie) I observed that when the water is ejected there is still some pressure left (cloud). That gave me the idea to experiment with inserts for the 9 mm Gardena nozzle. Happily there is internet and I found a simulator tool for water rockets. http://cjh.polyplex.org/rockets/simulation/ When I tried to emulate different nozzle diameters, I came to the conclusion that the original 9 mm is the most optimal with a filling of 200 - 300 ml water. This (approx 30'%) is also recommended when you search the internet. Only increasing the pressure can make the rocket fly higher. Warning, do not go too high with your pressure!! You can find an article about burst tests here: https://waterrocket.uh-lab.de/lr010101_bursttest.htm Please do have a look at that site. With then pictures is my comparison chart. Be aware the calculated heights are only examples for comparison. They do not indicate how high the rocket really will go. I do not have accurate figures for air resistance etc. (What is indicated as “Total” is basically the max) ================================================= What you need for the rocket: Parts to buy: 1) A 500ml PET mineral water bottle. I used the bottle from Valser carbonated mineral water with a diameter of 65 mm You might have to scale the top parts to fit your bottle. 2) A garbage bag or plastic foil (rescue blanket) or kite nylon to cut out a parachute of approx 56 cm radius. How to make the parachute you can find here: http://www.uswaterrockets.com/construction_&_tutorials/Parachute/tutorial.htm The drawing for the dimensions of the parachute are in the pictures. To make the chute to behave like a cone, you can optionally sew or glue the dark parts (3 times) together. You can clamp the chute on top of the spars with the mini clamps, or with the “big”-clamp. Or you can sew in the chute material 3 pockets for the spars. 3) The faucet counter-part for the Gardena coupler that is used in the launcher. 4) A flat rubber ring to seal the water bottle to the adapter (Gardena sells it). 5) Some silicone grease Parts to Print: 1) The adapter. This part must be airtight. Print it with a wall thickness of 5 and top and bottom thickness of 4 layers. 0.1 mm resolution. 100% infill. Supports yes. 2) The fins. The fin.stl is for a 0.5 l bottle Print it flat 3 times with 0.2 mm resolution 10% Infill and no supports. Because of tight tolerances you likely have to sand the parts a bit or print it with 0.1 mm resolution. Because these fins are printed flat, it is stronger. 3) Print the STL file of the top part, Drill out the holes for the hinges with a 1.8 mm drill. 4) Print the spars to hold the parachute. Print it 3 times 0. 1 mm Fort the launcher platform: Parts to buy: 1) A Gardena garden hose coupler 0.5 inch 2) --deleted-- 3) A few meters of pvc tubing approx 0.25 inch to be apple to pump the rocket at a safe distance. With a special Gardena coupler you can connect directly to 12od pvc tubing. 4) An air valve. I used a car type from an old bicycle tube (fitting in the 0.25 inch pvc tube) 5) Tube clamps for the tubing you use. 6) An 8 mm wooden rod for the trigger handle to be cut to size. (you can print them also. The .stl is provided) 7) 4 camping type thin ground pins (max thickness 5mm). To secure the launcher to the ground. 8) A piece of rope (max 3 mm thick) to release the rocket from a safe distance. 9) A M3 fastener and nut approx 10 mm length. You likely have to cut it to size afterwards. Parts to be printed: 1) The launcher. Print it with 0.2mm, 10% Infill and supports. 2) The clamping ring around the Gardena coupler. Print it 0.1mm 30% infill and with supports 3) The trigger ring. Print it with 0.1 mm, 30% infill and supports. 4) Optional the trigger rods (I used wooden pieces) 5) Optional tubing coupler depending on the sizes of tubing you used (1 type is here with .stl files. Print them 0.1 mm 100% Infill). Assembly: The rocket: This is straight forward. It is advisable to (hot) glue the top part to the bottle. Before you install the top part, ream the hinge holes with a 1.8 mm drill. Use pieces of filament for the hinge. Assemble the spars and the chute together. Use the big or tiny clips from the bottom to hold the chute to the spars. (The small clips might not be strong enough. I realised that only 3 spars is not enough to have the maximum chute-surface. I glued in also some bamboo skewers on the fabric between the spars. With hot gluing the top to the bottom be careful not to damage the bottle, happily the bottom is normally the thickest part. Screw on the nozzle, with the fins installed and with the O-ring and flat ring in place. Use a bit of silicone grease on rings and the nozzle. The launcher: Right size tube in the Gardena coupler. Mount the clamp ring on the Gardena coupler (roughly at the bottom of the orange ring). Put the Gardena coupler in the launcher. Put the trigger ring on top of the clamp ring around the Gardena launcher and push the trigger rods in from the side. The old launcher base had design flaw and you had to file and sand the guides for the launching rod. This new design should correct that. Put the air valve in the tubing (You likely need some type of filler material). Clamp all tubing connections. Check if the whole system is air tight. Of course you have to adapt these instructions depending on the tubing materials you found. Operation: Insure the the launching area is free. Not close to power lines, rail- and other roads or buildings. Put some water in the rocket approx ⅓ ( approx. 2 dl for a 0.5 l bottle). Place it on the launcher. Pin the launcher to the ground with the tent pins. Lay out the small tube and the launching rope. Connect a bicycle pump to the valve. Make sure that no-one is close to the rocket when you start pumping. I did not go over 60 PSI in my tests yet, be careful. I am not liable for any accidents. Before you launch make sure that no one is close (You might get wet... or worse) The bottle can explode so never use any metal parts on the rocket!

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