Hovercraft V2

This is my hovercraft I will be competing with at the NYS Div. C Science Olympiad StateWide Tournament. Me and my partner build this, and is based off by Hovercraft V1, posted previously by me. To see V1: https://www.instructables.com/Rechargeable-Battery-Powered-Hovercraft/

Update 3/23/26: Me and my partner medaled 7th place at the Statewide Tournament, the top60 teams out of 570 total teams were there.

I bought everything from Amazon except the Tenergy charger and soldering iron I got from my coach, and some basic tools from my dad. The total cost ended up being around $140-160, but I already had 9 of the tools. I put in around $100 worth of items, with my friend putting in $40.

1. 1 12v centrifugal blower fan ->$10-13 https://a.co/d/bHMVSFl
2. 1 12v PC cooling fan -> $9-16 https://a.co/d/gC4ZXEc
3. 1 2-pack NiCd Tamiya connector batteries w/ charger -> $20-30 https://a.co/d/a7KfvzK (if charger works, don't buy separate charger)
4. 24 AWG electrical wire -> $6-10 https://a.co/d/dlI3hJH
5. 1 Alligator clips -> $5-8 https://a.co/d/3V6suXn
6. 2 spade male connectors -> $6-10 https://a.co/d/5cCWaOA
7. 2 DPST switches-> $5-8 https://a.co/d/gvuvUN4
8. 4 pair Tamiya connectors -> $8-10 https://a.co/d/cinXDnW
9. 25 pair 22AWG XH2.54 2 pin jst connectors -> $7-11 https://a.co/d/6tSSQiw
10. Foamboard -> $0.50-2 https://www.michaels.com/product/12-x-18-foam-sheet-by-creatology-10597609
11. Cardboard -> Use an old box
12. 1 Tenergy NiCd charger(must include Tamiya charger) -> $40-50 https://a.co/d/1HWvTC8
13. hobby knife or X-acto knife -> $7-10 https://a.co/d/b2UnoJl
14. tape -> $3-5 https://a.co/d/bgAWhKT
15. soldering iron -> $10-40 https://a.co/d/3jQLtTi <- this is $15
16. electrical tape -> $3-7 https://a.co/d/bzSyeg4
17. CA Gel glue
18. hot glue -> $10-20 https://a.co/d/hJkqM7D
19. screwdriver -> $10-20 https://a.co/d/5knqafq <- this is the screwdriver set i use for $13
20. 100 W 10 Ohm rheostat -> $25 https://a.co/d/08PSd1dO
21. wire stripper -> $7-15 https://a.co/d/6SWftmz
22. Set of 10 100g weights
23. 3 pairs of velcro straps
24. voltimeter

First, you have to cut out a piece of cardboard/foamboard that is 39cm x 39cm big. It doesn't have to be insanely perfect, but close enough. This will act as the base for the hovercraft. Draw the midway lines on the hovercraft base, so it will be easier for later stages. Draw a 2.5 cm border around the hovercraft. This will help for knowing how big the skirt will need to be cut. Now draw a 12 cm by 2.5 cm box in front of one of the sides, centered along the skirt border. Shade this box in, it will be where the thrust fan will be placed. Now comes the midway lines into play. Draw a dot in the intersection of the midway lines. Put a dot 1.6 cm above that dot along one of the lines. Now put another dot 1.6 cm below the center dot along the same line. Now draw a 3 cm long line, with the newly put dot as the endpoint. Repeat with the other dot(NOT the center dot). Connect the ends of the 2 lines. Now cut this box out, it will be where the air will come out of from the lift fan. Use the images provided as help

Mark a dot from each side (30% of the width), and create lines for each dot. The 2 longest lines should have foam board placed on them with the height being 10% of width. Cut out a piece (trapezoid-like) from a plastic bag that connect one end to the foam board, and one end to the cardboard edge. Create 2 of these pieces. Glue one side to the foam board, and one to the cardboard. Then create 2 more pieces, that connect one end to the cardboard, and one end along on of the lines along to shorter side, but make sure it is big enough to connect to the corners of the foam board. Glue the smaller opposite sides of the trapezoid ( /__\ ) glue the __ to the cardboard, the / \ to the / \ of the bordering plastic pieces. Use images provided for help.

Place the hole of the lift fan aligned with the hole in the cardboard/foamboard. Align the lift fan such that the the air flow vent is facing forwards toward the 39cm front side. Once you confirm the position, glue it down securely and place protecting cover if you want. When glueing it down, use hot glue so if you make a mistake, you can change it later. Glue to edges of the hovercraft, but make sure not to put too much glue down. Connect a XH2.54 2 pin jst connector to the wire of the fan. Check the images provided for help.

Then at the back side of the lift fan, at the other 39cm side, place a velcro strap on the place marked down, and also attach a velcro strap to the bottom of the cooling fan. place the PC cooling fan on the far side where u have it marked down. Make sure the side with the label is facing outward. Put in the protecting cover (facing outward) with the screwdriver and a wrench to tighten the nuts. Put the side with the label pointing outwards and the side without a label pointing inwards towards the lift centrifugal fan. now connect a XH2.54 2 pin jst connector to the wire of the fan. Check the images provided for help.

Make a small box out of foamboard by cutting out 4 squares and connecting them together such that the top and one side of the box is open. then simply place the rheostat inside. Hot glue the bottom of this box to the top of the lift fan.

I used 2 12v NiCd batteries, one per fan in 2 different circuits. (for Science Olympiad, only 2 fans were allowed, and only max of 12V per circuit). Place one battery left of lift fan, and one right of lift fan. Add velcro to the sides of the batteries and to the cardboard/foamboard, and just attach them. Try to balance it out, doesn't have to be perfect. Connect a Tamiya connector to the ends of both the batteries.

Lift Fan + 12V Battery + Rocker Switch: Get a Rocker Switch. Take the red wire of the Tamiya connector of the other battery and solder it to one pin of the switch. Cover in electrical wire. Take the remaining black wire of the Tamiya connector and solder it to the pin of the switch on the opposite sides such that there is a barrier between the two wires. Cover in electrical wire. Take 1 of the Spode Male Connectors. Put the wires of the JST-connectors of the lift Fan into the open end of the connector. Repeat with the other wire. Place the connector with the black wire onto the pin opposite the already soldered red wire such that they are on the same side. Place the connector with the red wire onto the pin opposite the already soldered black wire such that they are on the same side. Check the images provided for help.

Thrust Fan + 12V Battery + Rocker Switch + Voltimeter + Rheostat:

Look at the diagram shown above which explains it very clearly. The circuit is a remix of https://unphayzed.com/kit-instructions/hc26/, but with changes to the items used, the connectors, the fans, and the batteries.

Place the hovercraft in a smooth location. It doesn't matter which switch you turn on first, just turn both. It will just naturally head straight. If it is tilting to another side, just balance out the batteries or the rheostat. To change the speed, turn the knob of the rheostat. Max speed would be the side where the far wire is attached to, min speed or not moving would be the other side. To check what voltage the thrust fan is running, look at the voltimeter. If it moves in a different direction, turn the thrust fan by taking it off and putting it on again differently, as in more to the right / left.

Attention: The voltimeter is removable such that when removed, the circuit still works normally.

Hovercraft is not moving.

1. Make sure the batteries are charged to the max.
2. Turn the knob of the rheostat towards the max speed, min speed on the rheostat can also equal no speed or not moving.
3. Let the hovercraft rest for 30 minutes, before testing again.
4. Check internal parts.
5. Make sure no electrical points have been broken.
6. Check the skirt for rips
7. Check for physical damages.

One of the fans are not working.

1. Make sure the electrical solder points have not been broken.
2. Check if any of the wires have slipped out
3. See if the corresponding battery is charged
4. If the problem is with the Thrust Fan, turn the rheostat knob towards the max speed

If problems persist:

1. Take off the batteries fully charged and see if they work with other devices. If not, they need to be replaced. Warning: Do not throw the batteries out, take them to a recycling center, or search up a NiCD recycling plant, they can slightly toxic and poisonous if battery pack has been ripped, wash hands thoroughly after each use.
2. Replace the fans, they may have fried internally.
3. Check for physical damages, and replace as needed.