Monthly Archives: January 2016

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.

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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.

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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.

 

A gremlin in the works?

After the Christmas break, we are back up and running again here at the Advanced Structural Testing Centre. Testing is in full swing and we are currently just shy of reaching the 10 per cent mark in the current testing cycle we started just before Christmas. We have a long way to go yet but that doesn’t faze us. During the testing cycle we hear regular creaking from the airframe, but our ears certainly prick up when we hear something new and the aircraft has been making a few unusual noises we are not familiar with.

A creaking sound has been detected at the bulkhead of the aircraft where the baggage compartment is situated, so the client has come up to the Testing Centre to inspect the aircraft and see if they can shed any light to why this may be occurring.

Part of our job is to flag up anything out of the ordinary that we may find during testing and pass these on to the client. In addition, as our role is to test the aircraft and then provide the client data. The majority of our data that is logged onto graphs is consistent and symmetrical, but we get the odd data set where there may be an unexpected spike in the results and flags up a query for us to pass on to the client.

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The client will then analyse this data and compare it to their model and give them the chance to inspect the airframe during testing, whilst the aircraft is active in the testing cycle.

For the previous two days, System Services have been at the ASTC. System Services are a technical support company for users of fluid power motion control systems who besides ourselves, work with major international companies such as BAE Systems, Jaguar, Moog and Rolls-Royce.

As we run the testing cycles for the aerobatic aircraft constantly, our hydraulic ring main system and power pack are under constant pressure. These systems have filters on which must be regularly maintained, so the oil within the system is cleaned constantly and meticulously. We have a three micron filter in place meaning there will be no dirt or sediment within the system bigger than three microns. Due to this, we use a specialist company such as System Services who specialise in the maintenance of test systems.

We work very closely with Steve Barrett from System Services as he has an immense wealth of experience and knowledge of the maintenance of test systems, so this gives us the chance to pick his brains whilst he is helping us out here at the ATSC. Shane has used Steve and his knowledge for 30 years after he worked alongside test systems based at the University of Sheffield. Besides his work involving the maintenance and calibration of test systems he also works as a trainer with a wealth of experience, so if we experience something we are unfamiliar with, there is a likelihood Steve will have had first-hand experience of it can help shed a bit of light for us.

As our systems are operating in tip-top condition, we will carry on running through the testing cycle as planned, ready to make any modifications requested by the client should their investigations into the unusual noises we picked up require it.

 

ATSC’s interesting fact of the week

On this day in 1745 Jacques Etienne Mongolfier was born.

With his elder brother they would go on to demonstrate the first ever flying machine in 1783 first carrying a duck, a sheep and a rooster. Later that same year Jacques Etienne became the first human to lift off the surface of the earth in a tethered fight of a larger balloon!

What a legacy he left behind!