How the Rotor Challenge works

By Nicola Parr, who has volunteered with Hands On The Future and presented the Rotor Challenge as a STEM Ambassador since 2018

 Nicola Parr instructs an awe-struck female student. Photography by Tina Knowles.

The Rotor Challenge requires young people to use micrometers and verniers to precisely measure each of a set of 6 bolts to find the one used within the rotor. The accuracy of the bolt needs to be within a hundredth (0.01 ) of a millimetre to fit tightly into the aperture, and any mistakes could be costly when in operation. Compare this with width of a hair from your head which may range from 40 to 120 microns and is typically 70 microns (0.07 mm).

The 'Goldilocks' bolt is exactly 14.00mm in diameter, and the range of sizes available is from 13.90mm to 14.05mm, a difference of only 150 microns. Over the years, 99% of the students I've met have never seen or used such precision-measurement equipment (your average 30cm ruler from school wouldn't cut it here), so this is a massive challenge for them to use the equipment correctly.

Once they think they have found the correct bolt – which, believe me, takes some time to find - they comment on the fit of the bolt and why they think it's suitable. Does it have some wiggle room, does it require a lot of force to get in, or is it just the right size? And what of the effects if it isn't the correct size of bolt?

The rotor itself is the tail rotor from a Lynx Helicopter, kindly donated by the Army Flying Museum in Middle Wallop.