A few weeks ago on the "suspension for spool" thread I said I would post a sketch of a Twin Beam-Wing concept. I think this is a more suitable thread, so here it is (warts and all ).
(Edit: Made image bigger.)
Main features:
* This is an "aero above all" car. Everything else is there just to support the aero. I figure "drive on the ceiling" at less than maximum FSAE speeds (ie. DF=W at <100kph, (maybe <70kph?)). And more is possible!
* Aero is direct acting on the wheels, and easily adjustable for F/R balance via the flaps. Since wings are close to ground, and with wheels as skirts/end-plates, drag is low (no induced drag). The streamlined fuselage and wheel pods also lower drag for good economy.
* The aero centres of pressure are unlikely to be exactly above wheel axle lines, so some force acts on chassis through BJs causing some pitch/heave. This can be fixed by either; a) not worrying about it, b) reshaping the wings, or c) interconnecting the wings with two torsionally flexible spars running alongside the chassis and attached flexibly to the beams on their axle lines. Extending this last solution sideways gives a full width "live" undertray.
* The rest of the car is as simple and robust as possible, for quicker build and more testing. Chassis is mandatory roll-hoops/side-impact-structure plus a minimum of extra tubes. Direct acting springs can be soft because little aero load through them, and wheel cambers unaffected by body roll, pitch, or heave. So dampers also soft.
* If the beams look a bit bulky, then think of them as the main spars and ribs of the heavily loaded wings. Each beam-wing is attached to chassis at only four hard points, namely the 2x spring-dampers, 1x heavy duty ball-joint (say 12mm or 1/2"), and 1x low friction "peg and slot" for lateral control (using, say, 2 x 12mmID 6201 ball bearings). Jigging can be done with stringline and tape measure.
* Rear wheels are 10" diameter (x 8" wide), but fronts are smaller, maybe 8" diameter. Less is more! This is subject to finding appropriate tyres, maybe from off-road quad racers with knobs cut off. If necessary, fronts can be narrow 10" diameter. Note semi-circular panels in front wing that turn with the wheels.
* Steering is bevel-gearbox-&-pitman-arm, for less friction, backlash, weight, and cost than R&P+UJs, and better ackermann (two sinusoids to work with).
* "Necessary ballast" is Royal Enfield! Shown is the old style engine with the separate gearbox relocated to front of crankcase. Jawa or similar single also possible, either upright as shown, or laydown as discussed "Objectively" elsewhere.
* Important note: the final drive chain as shown will give some anti-squat under power (good), but also some wedge (bad - less LR load, more RR). So OS out of left turns, US out of right turns. This can be fixed by moving engine sideways so chain is on car centreline (or, less desirable, move BJ so in-line with chain).
* A Rob Woods/UB style spool-axle is shown, but a live diff can also be fitted (this is the reason for the 4 x axle bearings). Also camber and toe can be made adjustable by using two half axles connected in the middle with CVs (or well greased splines).
* A De-Dion layout with chassis mounted diff is also possible (my preference). In this case only the 2 outer axle bearings are required, together with CV'd half-shafts. BUT, this requires different kinematic location of the beam-wing to the chassis or else too much pro-squat (I didn't have room to show this on sketch - it's only A4). De-Dion is structurally similar, just some relatively small (but important) kinematic changes, so can be done as bolt-on "option".
* Finally, a first year or "limited resource" team can do this car without the aero. Use a RE, B&S, or similar engine and you have a simple lightweight car that is quicker to build than the usual wishbones-and-pull/pushrods&rockers-everywhere cars. And, all other things equal, it will have high grip and benign handling because of soft springs with no camber change (not possible with normal independent suspensions).
Comments and criticisms welcome!
Z