The cycle that broke the camel’s back

This week we have been running fatigue testing on our aerobatic aeroplane. We managed to get up to 4,792 cycles out of a mammoth 71,693 before we had a slight technical hiccup…

The loading fixture on the Whiffletree broke due to a failure in the welding. This happened simply because of the continual loading and reloading of the forces applied and began to form a crack in the weld which grew until it eventually failed basically fatigue which is what we are testing the airframe for!. This isn’t forgetting that we are placing a significant load on the structure, +/- 63 kN every 20 seconds! Happily  , our colleagues at the Nuclear AMRC quickly re-welded the loading fixture for us, so now we just have to reinstall it to get started with the fatigue testing again. This time, the join has been welded with a much deeper penetration weld than we were specified to start with, so we are very hopeful that this issue won’t recur.

Engine mount damage copy

Before anyone begins to worry, there was no damage to the aircraft itself because we had all our test limits tied down. This means when the airframe moves too far, more than it would move when it was cycling up and down, the digital computer control will shut down the cycling and return the actuator to a safe position. We currently only allow the loading actuator  to move 3mm outside the specified range during its cycles before it cuts off.

In other news, Show Boss Phil got the chance to go down to The Royal Institution in London to watch the launch of the Soyuz rocket with British astronaut Tim Peake on board yesterday (lucky sod). He was also able to have a look through the archives whilst there and got to peek inside the notebooks of Michael Faraday and Humphrey Davy – not a bad Tuesday as far as they go!

Set Designer Steve and Best Boy Ed are very excited about the launch of Star Wars: The Force Awakens, no spoilers please! Of course, Christmas treats are still being consumed in mass volumes, now so much so, that project Director Lynn says she never wants to see another mince pie again.

We wish everyone a peaceful and joyful Christmas holiday and the team will have more Whiffletree news stories for you when we return in 2016!

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s