WarHorse is great - but to exceed 65mph it needs More Power & a better Transmission. We explored our options, and concluded:- Build New - using Lessons Learnt. Trojan - retains our carbon frame concept, but with a simplified roller arrangement. It uses the same size of rotating hoop, but the subframe is a larger fabrication, with stronger engine, better transmission, & larger driving wheel. That driving wheel carries a vulcanised rubber drive surface (first used at end of our developments with Silver).
WarHorse loads up its drive wheel with an air spring, plus another for suspension. Trojan combines these, and uses rider weight to put load on the drive wheel. That wheel is made with integral flanges (to eliminates a separate guide roller), has a freewheel built into its hub, and brake disc attached to its side. The goal was to reduce number of parts, and achieve lowest possible rolling resistance, with the mass concentrated at BDC. We spaced out the guide rollers (taking advantage of the High Tensile hoop that we'd developed for WarHorse), modified those guide rollers (with deep parallel flanges), and mounted them on special rubber bushings. We increased space in front of the rider, and flattened the frame behind him. That straight edge is best to identify which of our wheels you're looking at.
Trojan is built around an Aixro XR50 Rotary Wankel Engine. Smooth, Novel & Sweet.
The lower roller is a large flanged wheel under the seat with rubber drive surface. It’s mounted in a sub-frame with the water cooled engine, transmission, freewheel, hydraulic brake & exhaust system. The carbon frame, twin radiators, handlebars, battery & rider are separated from sub-frame with an adjustable air spring.
Our Aixro Rotary Engine produces 45hp & runs smooth at 11,000rpm (3 times the power of WarHorse) & involves a custom inlet manifold and centrifugal clutch. It's a superbly compact internal combustion engine from Germany, with an amazing pedigree in Kart racing. Maybe a bit strong for a Monowheel? but we set ourselves the challenge to tame it - because it's Novel & Fun. It has excellent Power to Weight, and suits our need to focus mass at BDC.
It is fantastic (up to 3/4 throttle), but extracting that last 25% has caused us some challenges with heat & fuelling. We're still working thru carburettor mods, & soul searching wrt a switch to Fuel Injection. It's tricky to analyse at this rating on track - so we built ourselves a load rig to help us address these issues (see Load Rig page).
Trojan Parts:-
"The whole is greater than the sum of its parts" - Aristotle.
Manifold
Mock-ups concluded that we would package our Aixro XR50 rotary power plant tipped up at 30deg from horizontal, which meant there was no way the standard manifolds would be suitable for Carb or Exhaust. The exhaust is shown above, but the inlet manifold was a sub-project of its own. That's because this engine uses a vacuum actuated power valve to a boost port - which needs a manifold to feed 2 engine ports. We had to make our own, and chose to do this as a casting. Geometry was developed by 3D printing. When satisfied, we printed again to make male & female casting patterns. We paid for this to be cast in sand, then got our machinist to mill & tap to produce the finished part. Massive thanks to all who helped.
Carbon Frame:-
Up to 20 layers of carbon & glass are bonded in a wet layup with lasered inserts over pins on a 2D jig. Boards are used both sides of the layup (for a smooth finish), vacuum bagged to squeeze out surplus resin - and achieve incredible strength to weight. The jig was designed so Left & Right sides are identical, with the pins and metal inserts ensuring accuracy and strength at critical points. After trimming, the two sides are bolted together with a combination of plastic, aluminium & stainless spacers. The fuel tank is also structural and reduces flex under the handlebars. Suspension pick-up points are further reinforced with external spreader plates.
Subframe:-
Everything starts on CAD, but we follow that with mock-ups to check that parts (& ourselves) will fit the design. This route also allows rest of the team to input their ideas. We feed these improvements back into the CAD (& further mock-ups) before starting the build.
Once frame design was agreed, we made a jig board to tack weld cut sections of stainless box. Like the carbon frame, this jig was made to suit both sides of the structure. When tacked, each side is joined by various cross members, and & folded plates that carry the main axle bushes & brake assembly. Once we have a fully tacked 3D structure - we move into structural welding. We are fortunate to have access to some phenomenal welders (some say they can weld Wood to Glass !). We use Stainless for all of this fabrication - 'coz it's Nice.
Suspension points, support stands and axillary items are all considered during this detail design & mock-up, resulting in a Master CAD Model. We take geometry from that master model to generate Detail Drawings for virtually all of our part. The principle has proved a godsend during this years covid restrictions (see WarHorse-E).