Project News

Electric flight isn’t new, and we were reminded of that in last month’s issue of Light Aviation with the feature on Rolls-Royce’s record-breaking NXTe aircraft. Of course the naysayers will point out that you can’t make a three-hour flight in an electric aeroplane and refuel it in 10 minutes. Maybe not just yet, but Tim Bridge is looking to provide the benefit of electric flight to remote communities in the developing nations who don’t have access to roads, fuel or mains electricity so that they can access medical services. An update on Tim’s project is below, and that first flight is getting very close.

Electric flight is coming and spin-offs from the automotive world will also help – did you know that last year nearly 12% of all new car registrations in the UK were pure battery electric vehicles?

As the world’s most popular kitplanes, RV’s are a constant feature in both the New Projects and Cleared to Fly lists at the end of this column each month. Serial builder Robin Rotherwick has shared some details of his latest project, an RV-8.

There’s another Sling 4 TSi build too, with Trevor Henegan and Lizzie Biggin choosing to complete their aircraft, at the factory in South Africa.

Finally, a little housekeeping. Project News has a new email address! To share your story, report a milestone or just to send a picture, please get in touch, and you can contact us at: projectnews@laa.uk.com

G-CLRR (LAA 381A-15664) Zenair CH750 Cruzer

Built by Tim Bridge – Nuncats

Tim has set out to show that not only is electric flight possible today with off-the-shelf components that are readily available but that it can provide social benefits to remote communities that a conventionally powered aircraft can’t offer.

Just a little over two years ago we heard from Tim when the project was an aspiration and a part-built standard Zenair CH750 airframe. At that point the structure was progressing normally as a regular airframe kit, with plans and designs for the electric propulsion, storage and charging infrastructure. Now it is almost ready for flight testing, as is the whole charging solution, which is burning only sunshine. This isn’t just an aircraft, but a whole ecosystem intended for use in remote areas where there is no reliable supply infrastructure for petrol or electricity.

The airframe is standard from the firewall back with the exception of the wing fuel tanks, their locations have been left as empty voids to hold two battery modules in each location. Forward of the firewall, the custom engine mount has the very compact electric motor at the front where the Rotax gearbox would be, and the volume occupied normally by the engine contains two more battery modules and all of the power electronics. A custom cowling will enclose the firewall forward in traditional style. With this approach the original design goal has been met where a ready-made component has been used unmodified, i.e. a standard Zenair CH750 airframe kit. No modifications, no new structural testing and no issues with weight and balance as the batteries are located in the same position as the fuel and engine.

The electric motor and all of the power electronics are also standard, commercially available items, some in use already for flight, making this an economic and repeatable process that has deliberately striven not to be bleeding edge.

The somewhat over-engineered prototype charging station has been constructed at Tim’s home airfield of Old Buckenham in the form of an ultra-sturdy steel carport, with solar panels on the roof and a couple of cabinets to hold the charge point and local battery storage. It is not intended to be grid connected and will collect solar power over many days in periods of poor daylight and accumulate it in the station’s battery storage. When required to charge the aircraft, the energy is taken from these batteries, not the solar panels directly, and so it doesn’t matter if the sun is shining or not. This ‘store and dump’ model is in use today in high-output electric vehicle charging stations. Under African skies, something far less elegant would suffice, just a few solar panels and a container a little larger than a bathtub to hold an array of lead acid batteries would accumulate enough stored energy to recharge the aircraft.

In use, the aircraft would not need to charge quickly, as typically a doctor or midwife transported to a remote community clinic may be there all day, consequently a bush charging site needs only a standard charger similar to a home EV charge point, although Tim has plans for an optional fast charger that would charge the aircraft in under 90 minutes.

Three real world interested parties have come forward as potential test cases, one in the Amazon, one in Congo and one in Uganda. The Ugandan case is a health clinic only 15 miles from base, but due to the terrain and lack of roads, the doctor is transported to site by canoe, therefore wasting a lot of medical time. Not a pipe dream, this is an existing all-day clinic being provided once a week the hard way, and potentially a perfect application of sustainable electric flight – and well within range and recharge times.

While waiting for the paperwork to test fly Romeo Romeo, Tim has plenty of ground testing to be getting on with. The aircraft will fly like the standard CH750 that it is but the power delivery, charge / discharge cycles, battery and electronic temperatures all need monitoring over many simulated flight cycles, fortunately this can all be done on the ground.

The only real custom part on the aircraft is the custom engine mount. That is now in its final iteration as a manufacturing jig allowing their ready reproduction. In fact, the second airframe kit has been received and its construction is to be overseen by second year students at the International Aviation Academy Norwich. A really interesting project and I’m sure we all wish Tim every success with that first flight.