Advantages of different types
Advantages of different types of FF Single Track vehicles
A single track vehicle with a seat base less than 20â€ above ground level at ride height, fitted with a seat back capable of supporting the rider. The front suspension should not be steered.
The following applies to all FFs. It is intended to be chiefly useful to designers seeking to define the type which best meets their requirements
The Quasar and Voyager projects both involved study of the 'performance envelope' of the FF single track to try to gain a picture of the full potential. Since those projects others have gone on the produce other examples of roofed FF's (BMW, Benili, Ian Peagram) and the Peraves Ecomobile represents an excellent example of full enclosure. All these vehicle appear on this site.
The overall envelope.
Compared with a car the single track vehicle offers a solution to traffic congestion and usually parking problems. In some locations it also allows use of special lanes. Single tracks are normally faster, with more acceleration than cars. There are theoretical, but rarely obtained, efficiency and cost advantages.
Any effective FF, one that offers a genuine functional advantage, must retain these advantages, while avoiding the problems of motorcycles. It must be more comfortable. It must be easier to ride, with less marginal features, and it must be safer.
Or it must offer such a unique level of luxury (Ecomobile) or high performance ( NSU Hammock), that compromising some of these basic advantages is acceptable..
The performance trade off familiar to motorcycles - handling OR comfort - is largely avoidable in an FF. Like a performance car it is not necessary for an FF to be uncomfortable. Comfort, a good fit, is an essential part of a performance vehicle. An FF can also be manageable at higher weights than motorcycles, due to the low CG, although weight should always be considered a Bad Thing.
This implies that, for a road going FF there is no reason why the basics; - Comfort, Handling and Safety - should not be incorporated from the outset in all types of FF. The question of which type hangs on other issues.
Any individual constructor will discover that a motor vehicle costs several thousand pounds to complete. The basic 'open cockpit' type, typified by 001 Ducati 450 FF, is the most minimal and hence cheapest type. As an open cockpit single seater it has no seat transport, no wipers, washers, de-misters, closing transparencies or doors. These are substantial savings.
Every extension beyond 001-like, basic, FFs, increases the design and construction costs. FJ is significantly more complex, and better equipped, than 001and cost more in time and money to make. The Quasar, with just a roof, plus a windscreen to wipe, wash and demist, adds further components. All roofs add weight in the last place it's needed, above the riders head. Doors, even with an open cockpit will require careful design and more materials.
Most challenging of all is full enclosure, where opening doors with large transparencies are required along with controlled airflow and heating. Some level of the technical difficulty can be gauged by the number of very expensive supercars that leak through their exotic door arrangements. The Ecomobile demonstrates that all can be done, with some style but there is a substantial cost.
Although the 295Kg Voyagers are much easier to handle than a similarly heavy motorcycle, there is no doubt that this figure is close to the top of the acceptable weight for a leg-supported single track vehicle, especially if a passenger is envisaged. I believe the Quasar is above the acceptable envelope for general use.
Above this envelope some form of outrigger system is needed. The Ecomobile demonstrates a functional system and although the dramatic shape and aerospace construction excite more interest the outriggers are actually the key components. Anyone building a vehicle with a design weight above 300Kgs should be considering outrigger systems.
These are not simple, fail-safe is difficult to achieve, ergonomics are tricky and some cost is unavoidable. I have done some design work on outrigger systems but other designers and constructors have real experience of such systems and a better qualified to describe the problems and solutions.
The weight and cost factors are just the consequences of more basic design decisions. Chief of these is the nature of the passenger arrangement. If no passenger capacity is required there is little reason to go beyond 001's level of complexity. If a passenger is to be carried then the open cockpit 'leg-supported' type demands careful packaging to achieve a reasonable weight and drivability. It also requires the two occupants to be closely fitted together. Although the rear bodywork obscures it the Voyagers just use the â€œKing and Queenâ€ stepped seat familiar on 'low-riders' with a movable single seat back..
Two-up, the rider uses the passenger as a seat back. This may be regarded as excessively intimate by some designers, although motorcycle passengers have always been in similar proximity.
If it is desired that the passenger sits further from the rider, using a separate seatback for each, it is extremely difficult to fit these people inside a motorcycle-like wheelbase and urban agility will inevitably suffer. Again, the Ecomobile demonstrates the wheelbase/agility consequences of providing a car-like passenger space.
The open-cockpit type is the simplest, lightest and smallest version. It should also be the most agile and efficient. Quite reasonable examples may be achieved by modifying a suitable motorcycle and Arthur Middleton's simple Kawasaki 500cc twin is a better than average example of a very basic â€œCut'n shutâ€ FF. The Comfortmax is also very good.
At the other end of this range FJ and it's relatives demonstrate the upper limit to weight and complexity for this type. Their major advantage might be described as â€œUtilityâ€ The ability to do everything useful a motorcycle can do, whilst approaching the comfort and serviceability of cars.
The next stage, avoiding outriggers but hopefully further improving the comfort, has universally been roofs. Some of this has been done in the hope of avoiding compulsory helmet use. In reality very few open-sided, roofed FFs improve the cockpit environment to the extent that wearing a helmet wouldn't be warmer, drier and quieter. The cheapest and simplest so far, the Benelli Adiva, seems one of the best.
All roofs, whether accompanied by doors or not, impose limitations on entry and exit to the vehicle and prevent the rider standing up and looking around. The visibility needed above the normal limits of windscreens, when turning into a corner has to be considered, as does the need for extremely narrow windscreen pillars to avoid obscuring obstacles.
The Quasar fails in all these aspects. These are important restrictions. Roofs do offer some improvement of the basic aerodynamics, 'hard tops' are generally cleaner than open tops, but a poor roof on an FF may be less use than a well-controlled open cockpit.
It may be worth considering side doors as an alternative route to better efficiency and a warmer cockpit. There needs to be provision for putting the feet down - or outriggers - but the result, resembling a Formula car should be efficient and offer a good cockpit environment. It would be easy to fit a cover over the cockpit opening not filled by the riders helmeted head and the small space occupied by the riders body would be easy to heat. Getting the legs in and out would seem to be the key problem to be solved.
Total enclosure takes the FF to the upper limit of it's range. Cockpit environment is completely controllable and the experience should be similar to a modern car in terms of ride, and noise. Safety should be the best available with seat belts and sensible cockpit design.
In theory, having solved the leg access problem with side doors, a fully enclosed, leg supported lightweight FF could be designed. Sketches of such vehicles, usually looking like a personal spaceship, are popular with potential customers.
The problems of combining so many features in such a small and lightweight package are challenging. If such a vehicle was made by a major manufacturer a team of people would take on the multiple problems, from the ergonomics of door and roof design, through the heating and demisting problems, to the careful integration required to get everything inside that leg-supportable weight limit
In practice it seems probable that the Ecomobile represents the typical total enclosure package, with well separated passengers and outriggers. However all these vehicles are packages of components intended originally for other layouts. The appearance of a powertrain that would fit entirely under the passenger space might allow packaging improvements that would make a smaller and lighter, even leg-supported versions possible.
Summary of types.
Designers will probably have a good idea of the type they intend to produce. Attention should be directed at the most pressing problems of the type chosen.
An open cockpit will need careful attention paid to it's environment, This is a matter of aerodynamic development which may be achieved with a few holes and some ducting.
Roofs need attention to the ergonomics and design, the windscreen requirements are as complex as for full enclosure.
Full enclosure probably requires outriggers, of which there are few successful examples and doors, with transparencies, that seal. These features present the most daunting technical challenges.
Open cockpit with side doors and leg-supported full enclosure have yet to be prototyped.
In reality open cockpit FFs have proved eminently practical all-round vehicles with many prototypes in daily use decades after the projects that generated them ended. A designer or constructor wishing to experience FFs for the first time would have no reason to go beyond this type. If later, a more complex type was desired, a basic vehicle would exist to carry out development on the specific problems of that type.
Clearly there is scope for experimentation and ample technical challenges to meet. Ian Peagrams development vehicle, based on a 650 Burgman scooter is an excellent example of a small roofed FF already showing exceptional fuel economy. Others are addressing the problems of full enclosure and outriggers and it will be interesting hear of their results.
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