Monday, May 30, 2011

Day 1 of assembley

We began launch pad assembly today with a trip to the local hardware store.  Our plan is to make 11 ground-level launch pads, and one overhead launch pad.  We had quite an interesting cart load of PVC fittings, with 44 end caps, 22 t-connectors, etc.  Unfortunately they did no have all of the female couplers, nor did they carry tire stem valves.  No project is complete without having to make multiple treks to the store.

Of 1/2 inch PVC we had plenty from a previous project where we built a kid's sprinkler.  We just had to plan our cuts to avoid the holes I had drilled in the PVC to make the fountains. (we will revisit that project probably this summer with some lessons learned from this version)

So, cut list for one ground level launch pad:
In 1/2 inch PVC pipe cut:

  • 4 pcs 6" long (side legs)
  • 2 pcs 4" long (middle legs)
  • 1 pcs 1" long (bottom upright)
  • 1 pcs 17" long (main upright)
You will need the following connectors for 1/2" PVC:
  • 4 end caps
  • 3 t-connectors
  • 1 male coupling
  • 1 female coupling
  • PVC cement
The male/female threaded couplings are optional; I want to be able to break these down for easier transport.

When we get to the trigger portion you will need
  • 8 zip ties
  • duct tape
  • hose clamp (to fit the 1/2 inch PVC)
  • The center portion from a 2 liter bottle
  • String
  • A scrap piece of PVC for the string to go throug
Not sure exactly how much all of this would cost, as I have a few of these laying around (particularly the 1/2 inch pipe).  Looking at my receipt:
  • 1/2" end caps: 4 @ $0.26
  • 1/2" tee: 3 @ $0.30
  • 1/2" Female adaptor: 1 @ $0.44
  • 1/2" Male adaptor: 1 @ $0.31
  • Hose clamp: 1@ $1.05
So, that much is about 3 bucks.  Under $10 for the entire launch pad and I have party favors for the LDRB birthday party!

Here are some shots of construction:
Not precision cuts, due both to the fact that there are random holes in our re-used PVC, and that it is hot as heck out there!

The new batch is shorter than the Mark 1 launcher we built as proof of concept.

Sunday, May 29, 2011


29 May 2011

This past Christmas one of the kids received this book: Soda Pop Rockets.  After reading it and doing some experiments I found that the clothes hangar launcher method described in the book just did not work well, at least in the rock hard clay soil of our area.  I was also able to get some used inner tubes from a local bike store (free!), but still had problems with reliable launching.

In the mean time, my eldest asked if she could have a rocket birthday party.  When a young lady asks to have a rocket birthday for her 13th, how could I say no?  However, we had to solve the launcher issue.  Thank goodness for the Internet and helpful people like Slater Harrison who has some wonderful instructions on his web site,  His method of heating and bending PVC, along with the launch release described there, is nothing short of genius.

I have successfully implemented my Mark 1 launch pad based on the picture he attributes to Tracy Bahr of Wisconsin.

We are able to reliably and repeatedly launch 2 liter bottles to an impressive height.

So, now we are on to the project of building 10 of these launchers.  These launchers will be the party favors the kids take home from the upcoming birthday party, or

Large Dangerous Rocket Bottles
Named, of course, after the show that was on the Science Channel, which was extremely popular at our house.  I'll try to post cut lists and pictures in the coming days.

So, let the countdown begin!