Project News
Zenith CH 750 (LAA 381-15664) An initial report by Tim Bridge
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uncats is a registered Community Interest Company (CIC) established to change the shape of E-Mobility in developing countries. They have the blessing of, and indeed have partnered with, the Zenith Aircraft Company to develop an electric power system for an otherwise almost standard Zenith CH 750, plus an off-grid charging station to suit. Their goal is that the whole system could be used to provide really useful rural transport and medical supplies in areas where fuel, roads and infrastructure are a problem in general. The airframe is under construction now and they have just started on the first of the power system elements. The key aim of the project is to demonstrate the viability and utility of electric powered flight, using cost effective and existing technology. Subsequently, supplying the home market on a commercial basis would then allow charitable organisations to be supplied at cost. There are NGOs in Africa working on health and conservation projects on tight budgets and in very remote locations, using light aircraft as flying jeeps. Totally ‘off grid’, the supply of fuel can be a challenge, and these aircraft need to be cheap, rugged and easily maintainable. In this environment, some of our Permit to Fly types could be made perfectly suitable. Rural solar generation is not uncommon in much of Africa and, by tapping into that existing infrastructure, an energy source is potentially available to fuel such an aircraft – after all, sunshine is far more widely available than avgas in the bush. There are many projects underway by big names in the aerospace world to produce fast, efficient, loadcarrying prototype electric aircraft, stretching the limits of current knowhow to eke out that last little bit of performance. Nuncats’ approach is different. Why design a new aircraft when they can work with what currently exists, sacrificing leading edge performance for economy and quickly bringing it to market. We know it takes a long time for a new type to be developed, so what’s the point for a small gain in efficiency? Its premise is to use what’s already out there and that includes the airframe. As an aside, consider any airfield, many of the aircraft are decidedly vintage, these older craft are unlikely to be scrapped any time soon, so even some of these could be electrified. For bush operation, an aircraft needs to be rugged and repairable, a delicate composite tadpole would probably not last past the first inevitable mishap – nuts, bolts, pop rivets, aluminium and straight lines make for a much more maintainable structure. The Zenith CH 750 and similar models are just the sort of ‘jeep’ that are needed, and there are a number in the theatre already. The creative focus in this project is almost purely firewall forward, where an electric motor with sufficient power to replace a Rotax 912 is a tiny affair – imagine a stack of six to eight dinner plates and you just about have the shape and size. So, a new motor mount will be required, and this may well be longer than the original item, and as a result, new cowlings will need to be moulded. All of that space between the firewall and motor can then be filled with power electronics and some of the battery storage.
Above The fuselage ready to come off the bench and onto its wheels. Photo: Tim Bridge
Meeting 100-hour services in the middle of nowhere also presents its challenges, so the almost total lack of a frequent maintenance requirement upon an electric motor, with perhaps two moving parts as opposed to hundreds within an internal combustion engine, also benefits remote aircraft operation. Apart from building the airframe, they will create a total system where a practical and useful electric aircraft is the outcome of the project. It is a fact that today the energy density of petroleum spirit cannot be matched by batteries, and it possibly never will. Equally, the simplicity of refuelling by pouring that energy dense liquid into an aeroplane’s fuel tank will be hard to match. So, their solution is for multiple yet manageable battery packs that are rapidly swapped at turnaround to provide a reasonable range. They even envisage the possibility of a partial battery load so that fuel can be traded for luggage as we would consider in current aircraft. Solar powered charging stations will hold spare battery packs at the various stop off points along the regular route, with future plans to develop automatic reporting of their charge and availability status by radio or over the internet. Consequently, a modest range of 50 to 70 miles is perfectly adequate to fly a route that is effectively several hundred miles, but made up of multiple legs, as are the existing missions flown by charities. These outlying charging stations, a mesh network, can then take days or perhaps all week to replenish the packs deposited there. This might not be flight as we currently know it but it would enable off grid operations that can both save and improve lives. Closer to home, the endurance would be very suited to flying school one-hour training slots. April 2020 | LIGHT AVIATION | 15
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