I haven't tagged as OT this time as I has dawned on me that the Cyclemaster is likely to remain as stationary as any of my other engines - I really can't see myself going through the bureaucratic nonsense of getting it registered and then for ever after either MOTing and taxing or declaring 'SORN' every year. I believe that in the USA and much of continental Europe there is a whole class of marginally powered vehicle which can be used on the road without these encumbrances (why is it that we only get the crummy stupid restrictive bits of European law?), while in UK this luxury is enjoyed only by electrically assisted pedal cycles, presumably due to the illusory 'pollution free' nature of electric vehicles.
In this respect, may I bore you with the following edited version of an article which I wrote for 'Stirling News' a while ago:-
Stirling Rider UK?
Flicking through Andy Ross' book "Making Stirling Engines" a while ago, I began to ponder whether his 'Stirling Rider'* bicycle, which he uses as a mobile engine test bed, would be road legal in this country and if it could perhaps be developed into a commercially viable product.
It is interesting to note that there has recently been something of a revival in electric vehicles of a type that had been largely forgotten since the failure of the Sinclair C5. These are covered by a piece of legislation known as 'EAPC (1983)' which defines an Electrically Assisted Pedal Cycle as a two wheeled solo machine with a maximum continuous power of 200W and weight under 40Kg, rising to 250W and 60Kg for tandems and trikes. Powered speed is limited to 15MPH in both cases. A 'dead mans handle' type of power control is required such that drive is removed if the rider releases the control, other than that the regulations are no more stringent than for a push bike and the machine can be ridden on the road by anyone over 14 with no need for a licence, road tax, insurance etc. Certainly an attractive proposition. If it could be demonstrated that a stirling powered version was able to meet these requirements, then its use on the road should logically be permitted on the same basis.
Unfortunately, road vehicle legislation in this country seldom has much to do with logic and I suspect that 'pioneers' would be in questionable position with regard to the law until the authorities decided how to treat such a vehicle. A similar situation arose recently with the Go-Ped, a sort of unholy union between a child's scooter and a two-stroke strimmer engine. Some people apparently used these extensively on the road with impunity while others were stopped almost as soon as they set out, the distinction being made largely at the whim of local authorities or even individual police officers. In that instance, I believe, a test case eventually determined that the Go-Ped should be classified as a 'light moped' and, since they fail to meet practically any of the construction and use requirements for that class of vehicle, their legal use on the road is now virtually impossible. However, Go-Peds are typically capable of over 20MPH, sound (and smell!) like a demented chain saw and are said to be somewhat deficient in the braking and steering department. A near silent and civilised stirling engine mounted on a standard bicycle would attract much less attention and one would hope that, should it ever get that far, the courts would ultimately decide a stirling assisted bicycle should indeed be regarded as equivalent to an EAPC.
One objection that might be raised is that the legislation is intended to promote zero emission vehicles, and to use any nasty fossil fuel burning combustion (internal or external) engine would be missing the point. While it is true that electric vehicles produce no pollution at the point of use, what their proponents usually fail to appreciate is that the vast bulk of our electricity still comes from coal, oil or gas fired power stations, and the process of getting the chemical energy stored in those fuels to the wheels of an EAPC is by no means loss free. Looking at some approximate figures for the most obvious sources of waste; generating efficiency is typically 40% and there is a transmission loss of some 7% in the national grid, then there are the NiCad batteries for which the usual charging instructions (14 to 16 hours at 0.1C) imply an efficiency no greater than
71%, and finally the electric motor for which data on units of similar output used in model aircraft suggests a figure of 75%. Multiply that lot together and you will see that without trying too hard, overall efficiency is already below 20%. Suddenly your 'zero emission' vehicle looks somewhat less environmentally friendly! Clearly an efficiency of 20% is still a pretty tall order for a small stirling, but at least it puts things into perspective and a more thorough examination of the battery-electric system could well reduce the target figure significantly (for instance NiCad chargers get quite warm and those motor efficiency figures are given at a fixed, optimum, speed). So, in this respect, a stirling assisted bicycle need not be at any great disadvantage to its battery-electric counterpart.I suspect the biggest barrier to any commercial prospects would be cost. EAPC kits range from about £400 for a fairly basic device driving the back tyre through a roller, to twice that for a deluxe job with a hub motor. Most of the component parts are probably off the shelf items in quantity production and therefore available at economical prices. Many parts for the stirling variant would have to be specially produced and therefore expensive, the challenge would be to simplify as much as possible. Could the clutch be dispensed with? If roller drive were used the engine could be disengaged simply by moving the whole power unit to take the roller out of contact with the tyre. Or perhaps the engine could simply be started and stopped as required, removing the need for both clutch and idle control. Once warmed through a small stirling should start easily at the first prod of the pedals. A variable power control then begins to look something of an extravagance and In reality would probably not be necessary with only 200 watts on tap (I once owned a Velo Solex moped which had a simple on-off throttle (coupled to the front brake!) and, though the thing had many other shortcomings, it certainly never felt in any danger of running away).
One question remaining is why bother when the battery-electric system seems to do the job perfectly adequately? The conventional EAPC is not without its deficiencies and, as ever with electric vehicles; batteries are at the heart of the problem. Firstly NiCads have a life of typically only a few hundred fast charge cycles and while some companies offer a recycling service, many more will probably end up gracing the local landfill site when their useful life is over. This not only means throwing away the energy and materials invested in the battery's manufacture but also releases some pretty unpleasant chemicals into the environment. The stirling variant would have no such short lived and potentially hazardous disposable parts. Then there is the matter of the range, variously quoted as 5 to 25 miles, after which a recharge taking several hours is required. By using readily available fuel, the range of the stirling variant could be extended almost indefinitely. One need never be caught out with what amounts to a rather overweight pushbike to pedal home. The batteries also slowly self discharge and must therefore be kept continuously, and wastefully, topped up if your EAPC is to be available for immediate use. The stirling variant would of course consume nothing during periods of inactivity and, given suitable fuel, would always be ready for use at a moments notice.
- I think the picture caption (in James Rizzo's Stirling Engine Manual) from which I took the title 'Stirling Rider', actually refers to the engine configuration (i.e. Alpha), but it seemed such an appropriate and catchy name that I just had to use it to describe the complete vehicle.