This week we’ve been continuing to set up the test – verifying equipment and ensuring any measurements we will be taking are accurate and traceable.
We calibrated the displacement on the actuator we’re going to use for loading – this will tell us exactly how much the plane is moving as we pull it up and down. We’ve borrowed a height gauge from the Integrated Manufacturing Group (IMG), which is calibrated to national standards, and used this to check and calibrate our linear potentiometer in the loading actuator. Now we know that if the actuator tells us the plane has moved 50mm , we can say within 0.05mm that that’s how much it has moved! The load cell has been calibrated externally obviously not with a height gauge! But against calibrated standard load cell. We take this measurement thing very seriously you know that if you buy a pound of apples from us you’ll be getting exactly 1 pound
After all the verification and checking we’ve installed the actuator ready for use and coupled it up to the plane. Unfortunately, there was a slight misalignment where the actuator bolts onto the loading pin. It’s only 20mm but we have to make sure everything is exactly right before we proceed any further so we’ll take it out and make it right!. Luckily for us, the job of re-aligning the actuator shouldn’t be too difficult, it’s only bolted down with four holes so we are hoping to have it done within a couple of hours and then we can re-check the alignment.
After this, we’re hoping to be in a position for a Test Readiness Review (TRR). At the TRR we will sit with the client and we will look at exactly where we are in the process. We will explain the progress and demonstrate to both ourselves and the client that we have prepared and checked every last detail to ensure that we are meeting the requirements of both the client and the airworthiness authorities. Once the TRR has been completed, we are hoping to be in a situation where we can place small loads into the plane and check the instrumentation for results. The client will be present for this and they can check the readings and see whether they tie in with the results they initially thought they were going to find. If everybody’s happy, we and the client will both sign the TRR. We won’t start testing unless everyone is 100 percent happy.
The client has also been in and modified the tail of the plane by cutting two holes and bonding two ballast boxes into which weight scan be placed to help ‘trim’ the aircraft . The centre of gravity of the plane has to be balanced and determines the peak performance of the aeroplane . Typically, the majority of the plane’s weight is in the engine and the propeller and the client wants to alter the centre of gravity slightly and this can be done by adding weight to the the tail.
Steve has just finished wiring all the strain gauges and coupling them up to the data logging system. The strain gauge wires are laid across the length of the strong floor, so we have been scrounging (by fluttering our eyelashes!) and have managed to get some metal caging we can use to cover the wire to protect the wiring from being damaged by people stepping on it.
Outside of the workshop, to celebrate the final of the Great British Bake Off, Phil has been busy baking and made the office a chocolate courgette cake. Despite its peculiar sounding ingredient list, everyone agreed it was extremely tasty, except Shane who thought it wasn’t sweet enough – you can’t please everyone, Phil! The first boxes of mince pies have also made their way into the office; it’s never too early to get into the festive spirit in Structural Testing!