I built this biplane glider out of straightened beverage can – estimated radius 70 mm.

It sort of works, but it needs frequent tweaking, and I’m never quite sure which tweaks are the effective ones.

Clearly there is stuff going on here that I don’t yet understand.

The next aim is to work out how to build a glider that works straight away.

What might be the important features. Here’s my list:

• symmetry
• right size of tailplane
• correct ballast
• Suitable angle of attack
• suitable wing loading
• Suitable wing camber

You might see from the photo that I have installed thin wires to help me to assess symmetry.

And why am I concentrating on biplanes? It’s because the wings of aluminium monoplanes are floppy and it’s difficult to maintain consistent angles of attack.

As you can see, I seem to have devised a reliable design for the fuselage.

Next I’ll see if I can build a glider that will fly without first requiring a long series of test flights.