Monthly Archives: May 2018

Air-powered rocket launcher

I built a rocket-launcher on the weekend. How often can you say that? This one is air-powered, and launches paper rockets high into the air.

My brother built one for himself a while back, and for Christmas he gave me the key part (the air solenoid) and some fittings.

The basic design is a H-shape, to provide stability for the base. Apart from the solenoid, all the pieces for the launcher are made from standard PVC pipe. A quick trip to Bunnings provided everything I needed.

Typical Bunnings trip. I then cut the PVC pipe into the right lengths. I drilled a hole into one of the end-caps, and put through an old bicycle-tube valve. I made sure that it was glued and silicon-sealed it well, for air-tightness.

All the parts were then joined together with standard PVC sealant.

I then put together the solenoid section.

Put all together:

I then have another pipe that goes in the top, which the paper rocket sits one. It’s just lauched with a simple 9v battery in a box with a momentary switch:

Overall, it works great. I think I definitely over-built it, it doesn’t nearly need to be this big, could easily be half the size and still work well. I left two joins to be screwed-in, rather than sealed, so that it could be disassembled to lie flat.

Script to change keyboard on Windows 7

I’m currently working in a client’s office, on an extremely locked-down Windows 7 PC. As usual, I want to change to the dvorak keyboard layout, which is my standard. However, the environment on the computer is reset every couple of days, which wipes out my keyboard setting.

So I started looking for a way to change it through a powershell script. Unfortunately, Windows 7 only has an extremely limited version of powershell. But I was able to find a way to change it using an xml script at these two sites:

Combining them both together, I put together the following xml file:

<gs:GlobalizationServices xmlns:gs="urn:longhornGlobalizationUnattend">

<gs:User UserID="Current"/>


<!-- Add Dvorak -->
<gs:InputLanguageID Action="add" ID="0409:00010409"/>

<!-- Remove US default-->
<gs:InputLanguageID Action="remove" ID="0409:00000409"/>


The trickiest part was finding the code for the dvorak keyboard, which is 0409:00010409

The code to execute the xml file is:

control intl.cpl,, /f:"Desktop\changekeyboard.xml"

Which I then put into a .bat file which I keep on the desktop. So, whenever, the keyboard changes, I just double-click the bat file, and the keyboard is fixed again, and I end up with the keyboards as so: