2013 is a big year for me, not least because at the end of 2012 I gained my authorisation from the CAA to display the Pitts aerobatically. This is a huge step for me, and not one I necessarily thought I’d actually be doing quite so soon.
Anyway, it’s happening, and as everyone knows, a good display has lots of daring, lots of noise and of course, lots of SMOKE.
G-BKDR is a fabulous little machine and has taught me more about myself than any other single item or event in my life has to date. She’s light, powerful, nimble and far more capable than I am at present. She was just lacking one thing to be the perfect airshow steed – smoke. Hence, over this winter my main project has not been a flying endeavour, but an engineering one. My little machine is now fully equipped with an absolutely first class smoke generating set-up. All we are waiting for are the final modification paperwork to be approved by the LAA and we’ll be back in the air practicing, training and tuning our sequences to not only [hopefully] win some more competitions, but to wow the crowds at the numerous displays I’m already booked for.
In between flying the Extra 200 (to save my sanity) and the Skyranger (for pure aviation enjoyment), I’ve been working hard on the mod for the aeroplane – there are several aspects to fitting something like a smoke system that you mightn’t necessarily ever think about, that is until you come to actually do it.
Firstly, it’s expensive. Ok this one was always obvious, but I decided to steer away from the DIY route as for me, a system like this, on an aeroplane as beautiful as ‘KDR, I wanted the workmanship to be better than I could produce myself. I also didn’t really know exactly what needed to go where or how to actually make things work. I was not in a position to take the easy option of fitting an off the shelf kit (such as the ones sold by Smoking Airplanes) as the only place the tank could go already housed an additional fuel tank…this meant a custom crafted tank to fit in the remaining gap was the order of the day. Definitely NOT something I could make myself.
Secondly, if it hasn’t been done in EXACTLY the same way on the SAME type of aeroplane, with all the same bits it is classed as a PROTOTYPE mod with the LAA. This means lots of paperwork, drawings, calculations and general headache. I cunningly managed to pass most of this on to my LAA inspector (in exchange for doing some work on his website).
Thirdly, it’s all so much more complicated than it first seems and the panels are an absolute pain in the backside to remove and replace – all told I think the strip and re-panel took me 12 hours of solid work in a very cold hangar!
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So how does an aerobatic smoke system actually work?
- You have a tank that holds a quantity of ‘smoke oil’. The oil is essentially a white mineral oil, very similar to baby oil. Diesel can also be used but is utterly horrible stuff so I’m steering well clear.
- Inside the tank is a ‘flop tube’ – a flexible tube with a whacking great brass weight on the end that flops around inside, allowing oil to feed even when the aeroplane (and tank) are upside down.
- Next up the line is a pump that pulls the oil from the tank, through the flop tube and out into the injectors.
- My system has two smoke injectors mounted into the exhaust pipes – the injectors work to simply spray the smoke oil into the hot exhaust where it vaporises and burns to produce the thick white smoke you see behind the aeroplane.
- Also in the system are a solenoid cut-off switch, to enable a really crisp on and off (rather than simply relying on the pump) and also a safety back up to cut off the oil supply in the event of any weird pump failure.
- The pump is powered from the aircraft battery and has various fuses and circuit breakers along the way. The actual use of the system is via two switches – one toggle switch on the panel ‘arms’ the system and an on/off switch next to the throttle actually commands the smoke on or off. Simple!
Getting under her skin…
So there we have it, all of the means to make some serious impressions in the sky!
Unfortunately the current phase is the tedious one – waiting for the paperwork. The system is finished, the panels all back on and the relevant stickers in all the right places, but until I’m given the ok we will be stuck safely on the ground. I can’t tell you just how excited I am to test this little lot out, watch this space…
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