Introduction: Hydrodynamic Testing Water Tunnel

About: I'm16 and in my free time I control cockroaches, weld, make canoes from duct tape, 3D print, make helmets, light big pieces of wood on fire, and other awesome stuff

I love the mythbusters! and have always wanted to test stuff with their equipment but it is sometimes one-of-a-kind! So I set out on a journey to build an inexpensive hydrodynamic testing water tunnel!]

a water tunnel is like a wind tunnel, it shows you how aerodynamic an object is. for example the cone I put in is aerodynamic at the front but at the back you can see that the dye is swirling and that would tell us that it has suction drag thus if this was a car less fuel efficient

Step 1: First Try

my first try didn't go too well but I took what I learned and built one that did work!

Step 2: Items and Tools.......


  1. gorilla glue
  2. glue sticks
  3. (2) 4 in to 2 in reducers
  4. (2) 2 in to 1 screw bushings
  5. 4 in (diameter) 2 ft (length) piece of SCH 40 PVC pipe
  6. a brazing/welding tip for an oxy acetlyne torch
  7. cement for PVC
  8. purple primer
  9. small nuts and bolts
  10. plastic eyedropper
  11. gasket maker
  12. food coloring (I recommend blue or black)


  1. drill
  2. saw
  3. tape measure
  4. glue gun
  5. hacksaw
  6. dust mask

Step 3: Prime and Glue

purple prime the ends of the pipe, all of the inside of the reducers, the outside and inside of the bushings and the outside of the screw bushing then using the PVC cement cement them together

Step 4: Measure and Cut a Window

find the exact middle (of the whole thing) then measure 3 inches in both directions. after that measure 2 3/4 inches up and down

after all that you will want to saw the vertical lines first then drill a few holes in each of the corners (so you can fit the saw in) and then saw along the lines!

SAFETY NOTE: PVC dust is toxic, always wear a mask when cutting or sanding PVC

Step 5: Cut a Piece of Wood

cut a piece of wood so it is 6 inches by 3 1/2 inches

luckily I found a piece that was 6 inches wide

Step 6: Chisel or Cut

measure a half inch all around (and mark it)

the objective of this step is to get a square window inside of the piece of wood. I did this two ways

  1. I drilled a few holes (so I could fit the saw in) and then sawed along the marked line
  2. I thought that was taking too long so with a screwdriver and a hammer I chiseled my way through the wood

after you have done either one (or both!) you will want to file down the pieces of wood that are sticking out

Step 7: Make the Piece of Wood a Window!

put the lexan onto the piece of wood and clamp it down then drill four holes in the corners (all the way through the lexan but only about a quarter of an inch into the wood) then take off the lexan and get a drill bit that is bigger than the head of the bolt and widen the quarter of an inch hole

after you have done all of that you'll want to glue the heads in

NOTE: though I say 'drill a quarter of an inch into the wood' I had a few problems with the bolts coming out so you could drill all the way through and put the head on the other side

Step 8: Make a Seal

using the gasket maker squirt a ring around the inner hole (of the wood) and put the lexan on it

then glue the wood onto the PVC pipe with gorilla glue

after you have done wait 24 hours (so the glue can dry)

NOTE: though I don't use it you will want to coat the places (that the gasket maker will touch) in anti-stick stuff

Step 9: Make Models (to Put in the Water Tunnel) and Glue a Medium Sized Bolt in the Water Tunnel

get a model car or something (cone shapes are the best) and hot glue a nut to the middle of it

then glue a bolt (it has to fit the nut) to the bottom/side (depending on how you look at it)

Step 10: Drill a Hole and Put the Torch Tip in It

my titles are really getting longer :)

using a drill bit that is about the same size as the torch tip drill a hole about an inch away from the window

then if you can't get the torch tip in (from the inside out) cut it a little bit shorter until it fits

after that use the caulk to seal the hole where the torch tip is is (remember you will want the head of thetorch tip where the model will be while the caulk is drying)

Step 11: Hot Glue the Pipe in Place and Add the Eyedropper

using hot glue glue the torch tip in place then get the eyedropper and push it into the pipe

NOTE: if the eyedropper doesn't fit into the pipe you will have to buy a different eyedropper

Step 12: Last Minute Flow Adjust and Defog

while I was testing it I found that the water was flowing too fast so I just screwed a CPVC piece

I also found that the lexan was fogging up so I added some SCUBA defog gel

Step 13: It Works!

screw your hose onto the opposite end that the eyedropper is on, turn on the hose, put in your model, and squirt some food coloring in!

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