Introduction: SaturnV Vacuum Rocket Launcher

Picture of SaturnV Vacuum Rocket Launcher

This project uses vacuum to try and launch a model of the Saturn V rocket into space !

It is is quite impressive to watch the forces involved, and guaranteed to impress anyone regardless of age. Firing one of these vacuum rockets, is an excellent way of understanding just how much one atmosphere of pressure actually is, and how much the air from ground to space weighs.

It is a great project for getting kids interested in science, including a bit of space exploration history.

Here is a slow motion launch of the Saturn V:

How does it work?: The rocket launcher consists of a long acrylic tube, with a thin layer of packing tape at both ends. To begin with the pressure inside and outside the tube is the same. When you then turn on the vacuum pump, you remove the air inside the tube, whereby the pressure inside the tube approaches zero, and remains one atmosphere outside. If you image doing this under water, then all the water above the tube, would try to enter the tube, with a pressure equal to all the water above the tube. The deeper under water you are, the more water above it, and the higher the pressure. On land the same thing happens, only air weighs much less than water, but the air above the tube stretches up all the way to the border of space ! You then rupture the tape at the bottom of the acrylic tube, whereby the the air is very rapidly pressed into the tube, pushing the Saturn V rocket upwards. Because there is no air above the rocket i the tube, there is little resistance, and it can be accelerated unobstructed to a very very high speed.

The project is partly based on 3D printed partes, and the final step explains how to get help printing the parts if you do not have a 3D printer, and which files to adapt to non-metric materials. If you do not own a 3D printer or a vacuum pump, this project is all the excuse you need :)

Step 1: Bill of Materials

Picture of Bill of Materials
  • Piece of wood 50x50x1000mm (1)
  • Heavy garden tile for base
  • Acrylic tube 100cm. Inner diameter 40mm. Outer diameter 50mm. (2)
  • Printed parts (See file names in images)
  • Mold making silicone (3)
  • Vacuum pump (4)
  • Vacuum tube. Inner diameter 6mm
  • Packing tape, or another self adhesive foil min. 50mm wide
  • Epoxy glue, or another strong glue
  • A few grains of rice
  • Screws, nails and paint
  • Eye and ear protection, it is loud !
  • Optional: Vacuum manometer and 6mm T-piece

(1) It can be anywhere between 45-52mm.

(2) If you can not get an acrylic tube in these metric measurements, the 3D parts can be changed +-20% to accommodate some variation. See the last step on 3D printing.

(3) http://www.makeyourownmolds.com/copy-flex

(4) You can get one- and two-stage vacuum pumps on eBay. One-stage is the cheapest, and sufficient for this project.

Parts needed for the Gantry:

  • 1x GantryA
  • 10x GantryB
  • 1x GantryC
  • 4x SupportArm
  • 1x Crane
  • 1x Hatch
  • 1x Trigger

Step 2: Gantry Base

Picture of Gantry Base

The base of the Gantry is a heavy garden tile. You want to make sure that the rocket launcher does not tip over. Place it towards one side, to allow room for the acrylic tube.

Place one of the Gantry elements on the garden tile, and mark with chalk where the wooden beam is going to be.

Step 3: Gantry Fixation

Picture of Gantry Fixation

Drill four holes all the way through the tile.

Step 4: Gantry Fixation

Picture of Gantry Fixation

Insert four long screws so that they just peaks through. Press the wooden beam onto the screws to mark where the screws are going to enter. Drill holes where the marks are, to prevent the wooden beam from splitting. Screw the beam securely in place.

Step 5: Gantry Paint

Picture of Gantry Paint

Paint red :)

Step 6:

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Glue GantryA and a GantryB together, and screw onto base. Add the remaining nine parts, and GantryC on top.

Step 7: Support Arms

Picture of Support Arms

Mount the four SupportArms, and the Crane at the very top.

Step 8:

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Unscrew the Crane again, and glue it onto the acrylic tube using epoxy or another strong glue.

Step 9:

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Insert some loose zip ties into the support arms. Add glue and tighten the zip ties. Screw in the Crane again

Step 10: Trigger

Picture of Trigger

Press the trigger into the socket. If you insert the socket into some hot water first, it becomes a bit more flexible, and less likely to break.

Insert and glue a small nail into the end. You can cut the head of a nail if you haven't got one without head. The nail is used for rupturing the packing tape at the bottom of the rocket launcher.

Step 11: Trigger

Picture of Trigger

Mount the trigger on the base, so that the nail hits the opening of the acrylic tube in the middle.

Step 12: Vacuum Pump

Picture of Vacuum Pump

Attach the vacuum tube to the Crane and the vacuum pump. The vacuum tube fits inside the Gantry.

Step 13: Hatch Silicone Seal

Picture of Hatch Silicone Seal

The rocket launcher has a removable hatch at the bottom with a silicone seal. If you do not want to play around with silicone, you can just glue on the hatch like you did the Crane, but it makes loading the rocket and applying packing tape much more difficult.

I have recently discovered a two component moldable silicone called Copy Flex, and it is now one of my favourite materials for DIY projects. Super easy to work with, and it creates a great flexible, durable and food safe part.

Mix them 1:1 and pour into the channel inside the hatch.

Scrape off any extra silicone to get an even surface. Just dump it into the middle, it is easy to remove afterwards.

Step 14: Hatch Silicone Seal

Picture of Hatch Silicone Seal

When cured, remove any overflowing silicone. This is easily done with your fingers.

Remove the inside guard, which was only there to keep the liquid silicone in place.

Use a knife to remove the last bits.

Step 15: Paint

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Paint the rocket black in the recessed parts.

Step 16: Launching the Rocket

Picture of Launching the Rocket

Put packing tape on the hatch, and press it on the bottom of the acrylic tube. Add a few grains of rice on the tape, to prevent the rocket from sticking to the tape.

Prepare the rocket by gluing on the three spacers. (I found that the spacers are actually not necessary)

Place the rocket on the support plate, and drop it into the acrylic tube. (the plate prevents air from rushing past the rocket)

Put packing tape on the top of the acrylic tube, the Crane.

Put on eye and ear protection !

Turn on the vacuum pump, and wait until the pressure does not drop anymore. If you do not have a manometer, this takes about 4 seconds.

Pull the string on the trigger.

Go look for your rocket in the neighbourhood :)

Step 17: 3D Printing and Files

When you print 3D files yourself, or get them printed somewhere, there are some parameters that are important, and some that are not. Only a few of the parts have some important parameters, so these are mentioned below, the rest does not matter:

Hatch and Crane: Print 100% to make them air tight.

Support arms: At least 4 outside layers to make them sturdy.

The .stl files are the ones you should print, or give to a print shop.

The .scad files are the ones you need to change, in order to accommodate non metric sizes, or other sizes of acrylic tubes. If you need to change them, I will gladly help, and upload a set a files for another tube size. Just let me know, I would be glad to see another Saturn V rocket launcher :)

Comments

Ethan1023 (author)2016-08-12

We are go for launch...

KronBjorn (author)Ethan10232016-08-13

We are indeed :)

ThomasK19 (author)2016-08-09

Doesn't the top film take quite some of the energy from the rocket's movement when it has to break through? And what strength does it need to be? I guess if it's too strong it will simply not let pass the rocket. And if it's too weak it will not hold the air pressure.

KronBjorn (author)ThomasK192016-08-09

I have tried two types of packaging tape (brown and clear), and foil cut round from a big sheet. They all work, so my impression is that it is not that sensitive to type of film.

Sometimes the rocket will break the tape, and sometimes the air pressure will lift the tape, before the rocket passes. You can only see this with a slow motion recording.

I have experimented with two layers of film, and it sometimes work, but a single layer is most stable.

Thank you for commenting,

amclaussen (author)KronBjorn2016-08-13

Nice Instructable. How about putting a lightweight cover that is held down by the vacuum, and then just blown away by the rocket. A simple way would be to seal the cover to the tuve with some thin grease. That could add some máximum height.

KronBjorn (author)amclaussen2016-08-13

That's a good idea. I'll have to experiment with that.

Thank you for commenting.

ThomasK19 (author)KronBjorn2016-08-09

I think that the slow motion of the rocket breaking through the tape would be fun to watch (maybe you can invite the Slow Mo Guys https://www.youtube.com/user/theslowmoguys)

KronBjorn (author)ThomasK192016-08-10

Yes wouldn't it be great to have equipment like that ! :)

I only once caught a single blurry frame of an object going through the tape.

AlexAndAmigos (author)2016-08-11

cool

KronBjorn (author)AlexAndAmigos2016-08-11

Thanks,

AlexAndAmigos (author)KronBjorn2016-08-12

I would have voted if I cold still vote. I hope you win.

sorry, typo, could, not cold

Mogger (author)2016-08-11

I made for my son an air pressure- water rocket from a soft drink bottle which is cheaper to make ( you need only a bicycle tire pump). It came back to earth parachuting. Ok, it does go up about 50- 80 m- not so high as the VAC rocket. But also a lot of fun!!

KronBjorn (author)Mogger2016-08-11

Yes, there is nothing like rockets, fire and explosions to get kids excited about science :)

John T MacF Mood (author)2016-08-10

Pretty darn neat work!

Having watched every manned launch from Alan Shepard's Mercury flight up to the last Apollo launch, and several shuttle launches, (all on TV, wish I'd been there.) This brings back memories.

Great job!

Thanks for the comment, I couldn't wish for a better reaction to a build :)

DylanD581 (author)2016-08-10

Nice rocket and launcher! Are you using a vacuum pump?

KronBjorn (author)DylanD5812016-08-11

Yes, a cheap single stage from eBay.

It is also good for other experiments, like inflating marshmallows and boiling water at room temperature :)

rbclima (author)2016-08-09

Really nice! Maybe u could blow some smoke around the launching base, it would make an awesome video

KronBjorn (author)rbclima2016-08-10

Thanks, that is a great idea.

Maybe it would also illustrate how air/smoke is pushed into the acrylic tube ? -I'll see if I get time in the weekend.

rbclima (author)KronBjorn2016-08-10

Yeh.... thats the idea, to illustrate the airflow

rbclima (author)rbclima2016-08-10

https://www.instructables.com/howto/Smoke+bomb/

Honus (author)2016-08-08

What an awesome project!

KronBjorn (author)Honus2016-08-09

Thanks,

tomatoskins (author)2016-08-08

This is so cool! I've seen this method for shooting ping pong balls laterally, but using this to shoot a rocket vertically is great!

KronBjorn (author)tomatoskins2016-08-09

Thanks, glad you like it.

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