(Well, we ask you to think about what we’ve learned don’t we…)
I almost wish I’d been doing an Application of Number project because this would have fitted perfectly…
I spent my annual leave attempting to build a hangar. (For this) Fortunately, given that I don’t know the first thing about construction, one of my flying partners is well clued up and arrived with a tape measure, roll of brickies’ string and a plan and all I needed to do was follow instructions.
Interesting and quite good fun to be a beginner at something occasionally!
We had a few ‘system requirements’ and ‘constraints’ to work to:
- It was not to look like a escapee from a shanty town and/or a refugee camp
- It was to be green (yes really – we’re trying to be non-obvious in the interests of neighbourly behaviour!)
- It was to have the same backline, frontline as the hangar (as yet un-built) next door
- It was to be no higher than strictly needed
- It was to have a three foot clearance from the next hangar and sufficient clearance from the hedge to get around behind for maintenance
- Someone my size has to be able to open the doors and get the aeroplane back out again, alone without inducing a hernia…
So we bunged the first peg in (at the back lined up with the back of the previous hangar and three foot further down the field.)
Things I learned…
- Eyeballs aren’t as accurate as you feel they are when estimating right angles!
- The way to double check you’ve got right angles at all four corner of your rectangles is to measure the two diagonals and check they’re the same length
- How to make a DIY land drain (Ditch, half lined with plastic, filled with stones then turf back over the top)
- Something called ‘postcrete’ exists which is superfast setting cement
- Renting a hole making machine only costs 25 quid and saves days of hard slog
- The slope on the roof so the water goes off without hanging around and leaking needs to be at least 1 in 20 (So 1 foot down for every 20 foot along – Ours is sloping from the front to the back because the top tip propellor sits higher than the top of the tail and we’re on backed onto the side of a field which slopes to the edges)
After pegging out (based on string, eyeballs and actually parking the aeroplane there to ‘draw round’!) we measured it out.
Across the front was 11 metres – that’ll be the length of the RSJ girder we need across the front to support the roof – it’s got to be strong enough to support that full length because no supports can be there or we wouldn’t get the wings out! 11m of RSJ is a big lump of metal…
We wanted a T shaped hangar (with the wings sitting in the crosspiece of the T and the tail in the upright – means there’s less roof and thus less weight and materials needed.)
Next job there fore was to figure out the proportions of the T. Again – this was mainly done by eyeball and string and pacing around the aircraft.
Silly mistakes avoided…
My scribbly diagram to take the measurements down looked like this…
“Hmm” I thought as I noted down the 6.3m on the arm of the T. “I didn’t draw that to scale very well…”
Can you see my error yet?
Perhaps not because my diagram isn’t (and wasn’t) really all that good, scribbled as it was on the back of a magazine pinched from the tea-cabin. But we’d divided it up equally, the T. The sections for the two wings and the body and tail were equal. We’d divided it into thirds.
So the base of T, on no account should have been different from the arm!
Neither should the measurements along the back add up to almost 5 metres more than the measurements along the front… (A little hangar we were building not the TARDIS)
I’d flipped two digits – the 3 and the 6… The 3.6 I’d measured got written down as 6.3!
What Application of Number would call “Sense checking” – my looking at the diagram and thinking it odd, and my remembering that the sections should be equal, hadn’t quite managed to clue me in.
Fortunately my formal checking method (“Adding back” in this case) did! Could have been something of an embarrassment otherwise!
The postholes are in and the timber is arriving on Friday for a weekend concrete postcrete mixing! We’re sharing the delivery of the RSJs with the builder of the hangar next door later and have prevailed upon the local farmer to lift it up for us when the time comes!