My World Record Attempt
Author: Mark Hopkins
The ECO Project, and how it all started.
The ECO-Project as I called it, started when I got into model helicopters in late 2001. My wife bought me a ECO-8 electric helicopter kit for my birthday which was my first ever RC flying model, I built it within a couple of evenings and learnt how to hover it in my back garden. I wanted to improve my flying ability and improve the performance of my model too, so I searched the internet to see what information I could find. After finding various tips on improving the model I stumbled across The Tyldesley Model Flying Club website, and on their records page was Richard Fry with details of his records. I was extremely impressed with his achievements. I also looked at the time he had achieved for his electric helicopter duration flight and saw that it was 13 mins 38 seconds. As I was already achieving flights of well over 10 mins at this time, using a fairly low spec battery and a basic ECO-8 set up for a beginner, (me) I thought that with a little practice and a decent battery I might be able to do better. As I know a bit about rechargeable battery technology, I was confident I could build a battery to fly my model for around 20 mins with my present set-up and beat this record. This seemed like a good opportunity to try to improve myself, so I decided to try my luck. The ‘ECO-Project’ had begun……….
I built a relatively mediocre Li-ion battery and tested the model, it could now fly for over 19 mins, so I contacted the BMFA to discuss about making an official attempt. John French the BMFA Records Officer kindly sent me a set of rules, and I started making my preparations.
While I was making my preparations, I was curious to know who the World record holder was, and what the record breaking time was. After a little investigation I discovered that the record was held by Jacques Boyer from France, and stood at 21 mins 41 seconds. I realised this was well within reach, if I used a more efficient motor, so I fitted one and tested the model,. I was pleased to discover that it could now fly for over 33 mins consistently, so it seemed as if I could have a go at beating the World record too. After contacting the BMFA again though, I found that Jacques Boyer had just had a new world record of an incredible 1 hour, 6 mins, 56 seconds, ratified. I was very impressed at this fantastic achievement, and I immediately knew that if I was going to beat him I would have to improve a little more.
I knew I would need an even better motor and a much better battery, also I needed to make the model more efficient. Jacques and the Aerodes Team had built a brilliant twin rotor model to increase efficiency, but as I did not have the time or space to take on this kind of project I would have to use a different approach, luck however, was on my side. When visiting my local model shop for some upgrades, Dave Charles, the shop owner, mentioned that one of his customers was interested in my little project and passed on his email address. The modeller was a very modest, amiable, and extremely knowledgeable chap called Nigel Fraser Ker, he asked if I needed any help with my project, which I duly accepted, and we formed a very successful team as you will see.
Improving the Model
The first step was to fit a brushless motor, but which one? Everyone I spoke to had a different idea. Eventually I spoke to the British Electric Flight Association (BEFA) and the Sandown Radio Control Show, and they referred me to Gordon Tarling who imports the Hacker range of brushless motors, he contacted Rainer Hacker who recommended the one I used.
Very shortly the model was flying far longer than ever before, but still not quite long enough for a serious world record attempt, so the next step was to improve efficiency. I started by fitting an ali chassis plate and carbon frames, to reduce vibration and for cooling. An ali swash plate went in next, which got rid of the plastic sliding plate mechanism making the model a lot more stable. Nigel then suggested switching from my new symmetrical glass blades to asymmetrical ones as these are more efficient for hovering, the problem was where could I get a set? I ordered the Ikarus glass ones but unfortunately they had been discontinued, so I seemed to be stuck! Nigel however remembered that the standard wooden ones that come with the kit are asymmetrical, I pulled them out of the box and fitted them back on and got an immediate improvement. This added about another 7% to my duration, but I still needed to do more. Next I experimented with pinions until I found the optimum ratio for my requirement, I also changed the gear ratio to the tail rotor, this increased duration slightly, but made the model harder to fly. Nigel suggested fitting a longer tail boom, to increase efficiency, I knew the ECO-16 tail boom would drop straight in, and is an ‘off the shelf’ part so that went in next. The result was an extra 2-3% duration, and a far more controllable model.
For the final stage I concentrated on the battery pack. I done a few calculations, figured out the best strapping configuration for the cell pack so the cells would current-share properly, and spot welded my new pack together. I was lucky enough to get hold of some