Quote Originally Posted by Z View Post
Jay,

"[In FSAE] To get the 40/60 distribution I imagine you would have to run some very short linkages, or else run them alongside and underneath the driver..."

All of these recent Beam-Axle drawings are meant to be quite general, and apply to a whole range of cars, not just FSAE.

For example, along with Ralph's examples from a few pages back (ie. racing on very rough tracks!), I have also got PM's from Baja students, and other more general enquiries. So, I drew the B-A(2) and B-A(3) sketches with quite long links so that they would suit long travel suspensions, much longer than is needed in FSAE.

In short, all the sketches would work fine in FSAE even if the physical links were MUCH shorter than sketched. Even with, say, 10" (250 mm) long links, the full bump or droop travel of 1" (25 mm) only changes the slope of the links by 1:10 (at most!), so much shorter links are NO PROBLEM.

And the Cylindroid itself is a "virtual" thing, so it can be placed anywhere, even off at "infinity".
~~~o0o~~~

"What are your thoughts on mounting the engine on the rear axle/arm with regard to driver controls? I imagine an engine moving about would have negative effects on throttle/clutch/gear control. Also there's the rule (assuming it's still a rule) that the intake must be hard mounted to the chassis. I guess one could argue that the suspension is part of the chassis but I could see it being an issue."

Yes ... the main problem is the Rules...

Again, considering the smoothness of FSAE tracks, I see NO PROBLEM with having an engine rigidily mounted to one of the "triangular" Axles, either the "Twin Beam-Wing" sketch, or B-A(2) or (3). With the engine mounted at the front of the triangle, nearer to the Body, it moves much less than the wheels when they go over bumps. And since no bumps in FSAE... (Or, looking at it the other way, many cars have won FSAE with effectively NO suspension at all...) And given that throttle/clutch/gear control can all be done via cables (and often are), I see no problems there either.

In fact, I reckon the ideal candidate for such Beam-Axle-mounted-drive would be the electric cars! Mount the heavy but compact motor(s) near the front of the Axle "triangle", just under the driver's back (ie. where the gearbox is in TBW sketch), and then take a chain or toothed-belt reduction back to the no-CV-driveshafts.

Importantly, the above amounts to "Outboard-Drive", so longitudinal n-lines have to be appropriately chosen. These are shown in B-A(1) as n2, but for good "antis-" they should have a LOWER slope, closer to that of n1. So either use a linkage similar to the TBW sketch, or if using linkages B-A(2), (3), or (4), then P should be lower, about the same level as R.
~~~o0o~~~

"I don't think the front beam plus flat floor underneath would be allowed/safe. I'd imagine you'd have to have another floor over the top of the beam. Was this your intention?"

Yes. The bottom-floor would be part of the aero-undertray. Any "cockpit-floor" above the Beam would be for the Rules.

"If so I envisage a humongous front end..."

Well, NO DIFFERENT to most Double-Wishbone FSAE cars.

Most every FSAE DW car out there today has a "stepped floor". This rises up roughly 100 mm from the seat-base to the footbox, just to provide suitable attachment "nodes" for the lower wishbones. Then there is a R&P that necessarily sits above this floor so that the tie-rods can get out to appropriate pick-ups on the upright, and keep away from the wheel-rim. And then another "cockpit-floor" above the R&P, to comply with Rules.

I figure many DW cars have this cockpit-floor at about 150 mm above ground (ie. at R&P location). Anyone care to share their numbers?

Anyway, a B-A(5) type Beam-Axle, albeit bent into a very wide "V" for FSAE, should be able to fit under a similar height cockpit-floor. Note the Pitman-Arm and tie-rods can be in front of, or behind, the beam, and the beam cross-section can be a widish, lowish, RHS, as sketched. Add the 350 mm high foot-box template, and the underside of the steering-shaft and Bevel-Gear-Box can be less than 500 mm above ground (the template has big semi-circular cut-outs at top and bottom for the steering).

It all looks very similar to most DW cars I have seen. From a quick check of photos, these have the top of their FRH at 600-700 mm above ground. Certainly, the tops of most noses at the front-axle-line are well above the tops of 13" front wheels (= 500+ mm diameter).

Z
Z,

The Cincinnati 2013 car had the nose around 150mm off the ground. A few weeks ago, myself and a fellow UC alumni put together some rough conceptual drawings for a frame that had the top tubes maybe 20mm above the OE of a 10" FSAE tire, that would package direct acting dampers at both ends of the car, use pitman arm steering and a whole host of other fun things. It's possible, but people have to think outside the box of what is common. We were using SLA front and rear suspension as well, so there is plenty of weight to be saved with a rear beam as well. I personally like the way SLA packages with the new bullhead support rules.

-Matt