Passed with flying colours!

Today was a great day! Last Friday, after all the ups and downs, we finished all the fatigue testing after we reached 71 633 cycles.

With this complete it was time for us to move onto the ultimate load test, performed once before, where the aircraft gets boxed in insulation and heated up to a toasty 72 degrees Celsius. This definitely helps take the edge of the February chills we have here in South Yorkshire.

So with the airframe all boxed up as you can see in the picture, we were all ready for the residual strength test to 64.85 kN which the airframe had no trouble getting through.

When this first pre-load test was complete, we moved onto the static ultimate load test which took the Game Bird 1 up to 82.65 kN. This is the highest loading that the airframe has seen to date, so it was a tense time for all involved. The Game Composites team were on site during the testing today, so we were all feeling the pressure!

17.02
The Game Bird 1, boxed in insulation for today’s ultimate load testing.

 

Fortunately relief spread across us all when the airframe passed with flying colours. There was the odd creak which was expected, although this didn’t help with the tension levels when we were all watching!

It has certainly been a very exciting week for us here at the AMRC and guided by the Civil Aviation Authority (CAA), it is now time for us and the team from Game Composites to decide what’s next when it comes to further testing for the Game Bird 1 aerobatic aircraft!

Stay tuned!

ASTC’s fact of the week…

On the 13 February 1923, Charles Elwood Yeager, better known as ‘Chuck’ was born. Chuck joined the US air force and flew out of RAF Leiston. During the second world war, he was shot down, escaped to Spain and ultimately to the UK and was flying again before the end of the war.

Afterwards he became a test pilot for the USAF and on the 14 October 1947 he became the first man to fly above the speed of sound in an aircraft named Glamorous Glennis, which he named after his wife.

Only two days beforehand he had fallen off a horse and broken two ribs – he was so worried about missing the flight that he did not tell the air force of the incident and chose treatment by a local vet to keep it secret!

Heres to Chuck, a living aviation pioneer!

Sometimes good things fall apart, giving us a chance to build better for the future…

After having a great week last week running the Whiffletree through the night and flying through some more of the fatigue testing cycles, we unexpectedly encountered a failure of the bolts connected to the engine mounting bracket.

That area of the aircraft is more highly loaded during testing than it would be in real life when in-flight, so it is running through the fatigue cycles in an ‘over-test’ situation. Unfortunately the bolts, which are grade 12.9 high tensile bolts, simply weren’t strong enough and had fatigued over time.

The failure caused the bolts to shear and pop off the rig, allowing the engine mounting bracket frame to bend, ripping through the weld and bening the arm of the bracket out of line.

IMG_7547crop
The sheared bolts from the engine mount bracket

 

IMG_7529crop
The failure ripped through the weld on the bracket

 

All testing stopped without any damage to the aircraft and we had to remove the whole front engine mount bracket to grind the entire weld out. This took Mission Controller Shane an entire day before we could then pull the bracket back into place and tack weld it together ready for re-welding.

The bracket was sent to our Nuclear AMRC colleagues who welded it back together on Monday. When it was returned we had some re-fitting to do, as the re-welding was done to both sides of the bracket instead of one this time. This caused the bracket to close up slightly from its usual shape so we had to jack it out to make sure it would fit.

The extra strength should serve us well as the fatigue testing continues, so taking the bracket off turned out to be a good opportunity to make some improvements and plan for future preventative maintenance; such as changing the bolts on a more regular basis.

The rig was back up and running this morning, so we conducted a 30 minute test run to bed the rig back in. We will then go round the rig, tighten everything back up and make sure nothing has moved out of place before resuming full testing again this afternoon and evening.

So even though we are only up to 54,400 fatigue testing cycles, should today go as planned, we could be back on 24 hour testing as early as Wednesday; maybe even finishing the fatigue testing completely by Friday!

Pop back next week to see what happens!

 

Making sure we have the perfect fit

After everything had been running smoothly last week, we began to notice an increase in movement and creaking of the air frame on the rig which we wanted to investigate.

Our client came in to also see what was going on and together we both decided to take off the wings of the Game Bird for a closer look. We re-looked at the bushings in the wings and realised there were a few tweaks we could make that would hopefully solve the unnecessary movement and creaking sound so these were changed and re-installed.

We also noticed on there wasn’t quite a perfect fit on the pin used at the front of the rig which was contributing to the unnecessary movement we had been experiencing. This was because it had been laser cut, which has the tendency to be a bit rough around the edges!

To solve this, we bored through with one of our lovely machines to make a bigger hole and fitted a brass bush so we could just push that onto the rig and the pin would go straight through it. Now we have a nice, tight-fitting pin which has reduced the creaking, so we are very pleased with the outcome.

All in all, everything took us about a week to complete but we are now back up and running.

Mission controller for the project, Shane, describes the plane running as “beautifully” so we have a very happy office. The alterations have made a great difference to the control so the movements are more progressive.

Shane decided to leave the aircraft to run through the night and has a webcam which is used to check the aircraft when it’s left to run alone. Unfortunately Shane has been checking it constantly through the night, much to his wife’s despair!

The plane did indeed run beautifully which was great news and this greatly increased the speed at which we are progressing through the fatigue testing cycles, having now completed 50,708 out of 71,000!

Here’s a quick video of the Game Bird aircraft during fatigue testing on our new and improved quieter and smoother rig…

 

We are going to run it through the night again which means we will be fast approaching the end of the fatigue testing cycle, when we will have another ultimate load test at high temperature to complete. Stay tuned for more news!

Introducing our aerobatic aircraft, the Game Bird 1

We can now announce the creators behind the aerobatic aircraft we have been testing here at the Advanced Structural Testing Centre (ASTC)!

For the first time in 30 years we can say that full airworthiness certification of a aircraft is taking place in the UK thanks to a pioneering partnership involving a championship-winning aerobatics pilot, an aircraft builder and ourselves.

Former German National Freestyle Aerobatic Champion and aircraft designer Philipp Steinbach is the brains behind the Game Bird 1 (GB1), which is being built by Lincolnshire-based Game Composites and is intended to be the world’s most fun to fly two-seater aircraft.

Headwaters of the Ganges River
The Game Bird 1 in flight!

The GB1 has been designed and built in the UK, but Philipp and Game Composites’ co-founder Stuart Walton, faced the expense of shipping the aircraft to the Czech Republic for full airworthiness certification, until Game Composites’ met our head of the ASTC (and project Show Boss) Phil Spiers at a Royal Aeronautical Society meeting.

Phil was determined that the production process should be kept within Britain, and although it would be the first time a plane has been designed, built and tested in the UK for 30 years; Phil was sure we had the skills and experience to make it happen.

The bespoke Whiffletree test rig was designed and built from scratch right here at the Advanced Manufacturing Research Centre (AMRC) with the help of welding specialists from the Nuclear AMRC and the AMRC’s own apprentices.

Phil and the team believe that the successful completion of airworthiness tests will open the way for the testing of light aircraft to return to the UK.

You can see the aircraft’s amazing capability, designed to help it carry our impressive aerobatic feats in the video’s below.

ASTC’s fact of the week

Concorde’s first flight was 40 years ago today in January 1976!

Its maiden voyage flew passengers from London to Bahrain in complete luxury, serving champagne, lobster, caviar and fillet steak during the journey.

Concorde flew passengers at supersonic speed during its lifetime, meaning a trip from London to New York was reduced from approximately seven hours to only two hours and fifty-two minutes!

Business as usual here at the Advanced Structural Testing Centre…

Everything is working as it should this week here at the centre and we are rapidly accruing cycles in the fatigue testing of the aerobatic plane.

So it’s business as usual and on with the show. We are now halfway through the fatigue testing having gone through 36,000 cycles and have started running extended cycles of testing setting the rig to perform from 6am until 10pm at night.

Should we get good performance from this rate of testing, we will return to setting the rig up overnight to clock up some more testing cycles.

Watch this space!

Even the best laid plans…

We’ve had a fairly good week at the Advanced Structural Testing Centre since our last post. As mentioned the customer visited us to see the aerobatic aircraft in action on the whiffletree testing rig to check out an unusual creaking sound and to review the data sets captured every 10 cycles of fatigue.

The aircraft is assembled on the whiffletree in an asymmetric way to induce twisting into the wings and fuselage as the load is applied. To achieve these torsional loads, it is necessary to mount the whiffletree on the right wing in front of the centre of pressure (CoP), to induce the correct amount of ‘twist’ in the left wing that is mounted slightly behind the CoP. Loading in front of the CoP wouldn’t happen in normal flight.

This means the right wing is not being tested representatively (it is being over tested). As the root spar of the left wing is smaller, which is the critical wing for testing; so if the left wing is good and the identical right wing with a bigger interface will also be good.

As the right wing is carrying this forward CoP twist it was necessary to put some patches on to stop the flexing of the skin inside and stiffen the assembly, hopefully preventing the unusual sounds, data and make the test run smoother.

The fatigue testing continued on Friday and Saturday morning and on Monday we felt confident enough to let the testing run through the night.

We set the testing cycle going at 4.00 pm and as all good parents do – kept a keen eye on its progress via a webcam – we do like to know what our children are up to! Just after 10pm the shutdown lights came on as the rig was no longer running. A brief investigation on Tuesday morning found the reason for this was a fatigue failure of a rig part.

The part was the thread of an adaptor where the actuator is joined to the load cell; this had fatigued and broken so the actuator could no longer put the loads onto the rig.

img_0344crop[1]

The MOOG controller had then automatically shut down safely. As the actuator became detached it fell onto the engine fairing attachment beam below the representative engine mount causing some damage DOH! This is the worst nightmare of the test engineer! Fatigue testing really does discover every little issue with the entire system.

img_5131crop[1]

The damage has not caused any structural problem to the aircraft and the customer was more pleased that we had tried to run through the night to get the test completed more quickly. Repairs were made by the customer on the same day.

We are now modifying the back end of the load cell to change the broken part to a larger diameter, this is so it will connect directly onto the actuator, hopefully minimising the risk of this failure reoccurring.

The larger diameter part is currently being machined by our AMRC apprentices based onsite at the Knowledge Transfer Centre workshop. A great advantage of being so close to our other centres here at the AMRC is the ability to collaborate closely with our colleagues and our customers, allowing us the flexibility to modify and repair parts at short notice. The apprentices are machining the modified part which should be back with us by the end of Tuesday, allowing us to start testing again on Wednesday if possible.

We are now just under 30 per cent of the way through the testing cycle, so once the modified part is fitted and we are running the fatigue testing cycles day and night, we should run through them fairly quickly!

 

ASTC interesting fact of the week…

Today is the 150th anniversary of the Royal Aeronautical Society, the oldest society relating to aeronautics and astronautics in the world.

Formed by the Duke of Argyll in 1866 to explore the science of heavier than air flight, some 37 years before the Wright brothers would take to the sky at Kill Devil Hills in North Carolina.

It is not just today that we have innovative thinkers and pioneers, The Duke was very much the Steve Jobs or Elon Musk of the 19th Century.