This week we have been making preparations for the temperature controlled static limit load test. This will involve us heating plane up to 72°cand performing a single cycle test on the structure. The plane will get pushed up and pulled down once so there’s a lot of work is going into 20 seconds worth of testing but it’s all worth it!
Show Boss Phil has been in touch with a company called SIG Technical Insulation. They kindly agreed to supply us with all the insulation material we require to insulate the plane, free of charge (he must have been fluttering his big eyelashes!). SIG pulled out all the stops to get the insulation material to us in break-neck speed. They bypassed the depot and got it delivered direct to us straight from the manufacturer in South Wales – we could get
used to this special treatment! A huge thanks goes out to SIG Technical Insulation for their support.
The team has been busy constructing a steel frame to lift the insulation that will surround the plane, a metre off the floor so we don’t unnecessarily heat up a lot of dead space. If we built a big box around the plane and the whiffletree as well, we would probably end up heating up around three times more the volume of air than necessary. By building a sealed chamber around just the plane, it will take less time to heat up and also use less energy in doing so, so it’s a win-win for structural testing and the environment! We are also making sure the whiffletree structure, that’s made of steel, the hydraulic actuator and the load cell are insulated too to reduce the amount of heat they absorb and ensure there’s no adverse effects on the measurements when we do the test.
On top of the steel frame we’ve built we’ve started to build a flat table-top structure which is a bigger footprint than the plane, to allow us to sit the four big electric heaters, which will be used to heat up the insulated enclosure, on. The client fitted a thermocouple on the wing spar of the plane; the wing spar is one of the main structural points of the plane; and it’ll be that thermocouple we monitor to decide when it’s hot enough to do the test.
If everything goes to plan with the temperature controlled static limit load test,, (the plane’s design engineer is as nervous as an expectant parent so for the sake of his sanity, we hope it does!) we can move onto the next step of the plan which is to remove the insulation and perform an inspection before conduct another static limit load at room temperature. If all that runs smoothly, we will rebuild the insulation chamber around the plane and conduct a static ultimate load testat 72°c.. This means putting an even higher load onto the plane at a high temperature so it will be a tense but exciting time for us all!
If all the static load tests go to plan, we’ll have the green light to start on the fatigue test which is made up of 71,633 cycles – but more on that in the coming weeks.