It’s A Plane

When I was a teenager, I used to belong to the Chester Model Flying Club (which now appears to be defunct :( ) and I flew electric powered gliders of about 2M wingspan. Typically a balsa framework, with a 540 motor and a 6 cell NiCad battery. Power (& skill) were marginal, weight was high, but I had fun.

I’ve always hankered getting back into it, partly becuase my route to and from work can go via the Nomansland Common where there are facilities to fly planes. I recently got a £200 award at work for being there 10 years, so I thought I’d get back into it.

Changes To The Law

Originally, I could basically fly anything. Being a club member gave me access to flying fields and a mdoicum of insurance. The planes I flew weighed about 1-2kg, and the radio gear I had was a basic 35MHz 4/5 channel set. It was a present from my parents for doing OK in my ‘O’ levels which cost >£400 in today’s money.

Today, if a plane weighs more than 250g, you need to register as an Operator which costs about £11, so I thought trying to build something below that would be a good challenge. Seeing as that is half the weight of the 7.2v NiCad batter I used to use, it was going to be fun! I had to register to get a Flyer ID by answering 40 multiple choice questions (I got 39 right) which tended to be of the form ‘Charlie wants to fly his 10kg jet 20m above the main runway at Heathrow. Is this a good idea?’ My Flyer ID is “GBR-RP-SFP7S69WHTQ9”

There were two models I attempted as a teenager that were failures. The first¹ was a twin boom pusher which I built too heavy and the best I ever achieved with it was a powered glide into the ground. This seemed like a good target to recreate if I was going to do it.

The original was a pull out plan in one of the magazines, which I’ve long lost so I’m basically going on memory. It was about 3ft wingspan, constant chord, elevator, aileron & throttle. Wing was meant to be foam, but I created a built up one.

In the interveining 35+ years(!) three things have changed

1. 3D printing
2. Much better battery/motors
3. The internet

Working with balsa and ply was hard. The wood was expensive and mistakes were easy. Printing ABS is cheap and mistakes are easily rectified. I’ve been able to weigh designs whilst they are still in FreeCAD. Whilst I was typing the last sentence, another 1Kg reel of ABS arrived that I ordered yesterday for circa £14. That would have bought me a couple of sheets of balsa in 1987. I learned about Kf aerofoils and how trivial wings are to make out of foam. Cut out a rectangle, fold it over and call it done. I bought a pack of 8 sheets from B&Q for £16.55 and I haven’t finished my first sheet.

The radio gear is a FlySky 2.4GHz 10 channel set with telemetry. I got it for £68, 16% of the cost of the original set, and much superior. The three servos I’m fitting to the plane weigh less than a single one from my original set. I’m spending a bit of my weight budget on a 3 axis gyro for stabilisation and an altimeter as if I’m meant to fly below 400 feet, I’d like to know what that actually is.

The big win is in motors and batteries. The circa 500g 7.2v 1200mAh NiCad is now a 30g 7.4v 600mAh LiPo. I’ve lost half the capacity and 94% of the weight. The motor is a brushless thing that weighs about the same as the battery.

All in all this hobby has got so much cheaper and simpler I can see this keeping me amused for a while. I’ll probably write more posts about the detail of the design/build in the coming days/weeks.