In order to research the operational characteristics of a proposed "Flying Automobile - the 4-D, Triangular, tubular framed, auto-airplane", architect and inventor R. B. Fuller constructed three non-flying, streamlined, three-wheeled ground transportation vehicles. Their primary purpose was to test the high speed taxiing stability should the auto-airplane ever be built. Important technological inventions necessary for the completion of the Flying Car had not been perfected at the time of the visionary design. Some included, but were not limited to, inflatable, retractable wings and gas turbine engines for lift and propulsion.
Fuller built and tested three (3) chassis configurations - all with two non- steering front wheels providing traction and braking with a single (1) rear, non- powered, steerable rear wheel.
While essentially similar in concept and physical placement of powerplant and transmission, the location of the three wheels and the general streamlined, aircraft fuselage like body, there were subtle external features which differed between models 1, 2, and 3. Driver/operator seating position is in front of the front axle, similar to a modern mini-van placement (VW - Vanegon, Toyota Van, etc.) utilizing a rear engine or under the floor engine/transaxle.
One version (Scale Drawing E18, p 100, The Dymaxion World of Buckminster Fuller) had a pair of recessed headlights, multi-paned windshield and side windows, seating for four, "teardrop" shaped front and rear doors, and a massive, girder-like subframe extending from pivot points at/above the front axle and extending rearward and upward to the rear wheel pivot stanchion.
In this version the rear sub-frame has parallel side components which converge inward at a point about at the front of the engine compartment and terminates at the rear wheel pivot support. In the elevation view the girder like structure is straight without a dogleg bend seen in other versions. The "straightline" design of this girder intrudes into the passenger compartment and would make entry and egress difficult through the rear side doors.
In the plan view of this design, the main chassis frame which supported the rear-mounted engine and the passenger cabin is a complex, curved - almost serpentine - platform with gusseted crossmembers at strategic locations to reduce torsional deflection. This frame structure was less massive and was supported by transverse leaf springs at the rear and at the widest part of the body above the front axle. Plan and elevation scale drawings labeled Dymaxion Car #1
This configuration is shown in one of three photographs ( mistakenly all of which are labeled as E29, E30 & E31 chassis of Car #1) In reality, only photo E31 which shows partial bulkheads, stringers and longerons of the body as well as the distinct, straight line girder like sub frame which match the scale drawings.
This completed vehicle - light colored finish and a single headlight appears in Photographs E34 - E39 displaying a 1933 Connecticut license plate FV 453 In one photo the multipaned windshield is shown while in several others there appears to by a curved aircraft like plexiglas, single piece windshield and side windows.
The most significant engineering differences were evident in a comparison of the sub-frame which positioned and facilitated the rear wheel suspension and steering.
In photograph E40 a comparison between a relatively heavy two-frame structure used in Car #1 and a delicate, three frame structure introduced in Car #2. I believe that it is this second frame which is actually shown in photos E29 & E30.
While the serpentine perimeter frame seems to be retained, the rear wheel supporting sub frame seems to be shortened and have its front most pivot points moved back from the driving axle position to a new location approximately in front of the engine. This removes the intrusive girder from the passenger compartment although it decreases the arc of rotation (the "swing arm action") and, perhaps adversely affects the castor angle (King Pin Inclination - KPI) of the rear wheel.
This car #2 shown painted Black in photos has two recessed headlights and carries a dark colored, 1934 Connecticut license plate SL 187. It shows a multi- paned windshield made up of triangular and rectangular panels and three flat paned, horizontally divided side windows rather than two single piece windows. As in car #1, there are no louvers for engine compartment air cooling in this version either.
Photo E42 shows a modification to the steering post angle and "A" frame construction in Car #2. Note that there is a canting of the wheel to one side with a corresponding angle of the pivot post away from the vertical so as to tilt the rear tire slightly. The chain steering sprocket is no longer flat and horizontal - it is tilted to match the pivot post inclination. It is supposed that a line drawn down through the steering fork "tine and a corresponding line drawn down through the centerline of the tire would intersect at the contact point at or below the roadway.
Car #3. photos E46-E48 on p. 106 shows a two-toned color scheme - light top, darker body with a chrome trim strip on the lower body displaying a 1934 Connecticut license plate HF 349. This version also utilizes a multi-paned windshield made up of triangular and rectangular panels and three flat paned, horizontally divided side windows. Unlike the two previous cars, there are four sets of louvers on either side of each engine compartment side doors. The prominent roof mounted air scoop on the previous models is absent while a "dorsal fin" like exhaust vent is added.
Both the driver and passenger doors are rectangular in shape and generously proportioned for ease of entry.
The Patent Drawings. This version shows a single headlight, three, two piece, side and door windows and a curved two-piece windshield. The third version of the rear wheel support with a front axle mounted pivot point is show, There are a pair of subframe side rails extending rearward - below floor level - to a point behind the rear bulkhead where the rails both angle upward and inward to the rear wheel steering stanchion.
The pivot axis of the rear wheel is again, vertical in orientation and a more conventional chassis/frame with parallel side members running from the engine support to the front of the vehicle is in evidence. Transverse, lateral, floor supporting members are carried by this main frame which is "Z'd" or kicked up to clear the live front axle.
The original vehicle was a compromise between the innovative and visionary plans of a gifted architect-inventor who envisioned a unique blend of what was and what might be. Materials science, manufacturing technology and the automobile and aircraft industries were somewhat bound by the traditional methods and materials. The Laws of Physics and the properties of materials and power sources then available to him, were dealt with in an atmosphere of, "when this or that becomes available, then these ideas will work as planned." Until then, we will design and test those concepts which are within our grasp waiting for the next phase which rely on inventions not yet realized.
Today, in 1998, with over 65 years of inventions, new materials, refinements and developments in automotive and aircraft technology and the advances in Manufacturing methods and technologies - What improvements, refinements, substitutions or alterations can be made to produce a Modern Day DYMAXION CAR?
Premise #1. The original, 1933 design incorporated some standard automotive components which were, more-or-less, state of the art for the period, utilized in some unconventional ways , ie, (1) solid front axle with transverse leaf spring. essentially a conventional Ford, live rear axle turned 'round to become the front, non-steerable, traction element, and (2) the rear mounted Ford V-8 flat head engine was reversed in the frame and, utilizing the standard transmission, drives the vehicle with a conventional driveshaft.
Q1. Could the use of a modern, IRS axle (Trans-Axle) with articulated CV joints and disk brakes be used effectively?
Q2. Can a modern torsion bar suspension with tubular - coil-over - shocks be used to advantage?
Q3. Can a pure Air Shock (Pneumatic, non-coil spring) be used?
Q4. Could an OLEO STRUT ( Air over oil) as in the French CITRON car be adapted?
Q5. Can the patented Jeff Stockton Positive Linked Suspension System - PLSS - suspension be incorporated as both a suitable front and rear springing device?
Premise #2. The original DYMAXION sub-frame which supports the steerable rear wheel extends from bearing hangers on the front axle housing. It was heavy (Version #1) and required several cross braces to resist twisting and torsional distortion. A subsequent design seems to be less bulky and perhaps has its forward pivot points at a location more to the rear of the vehicle.
Q1. How does this reduced overall length of the side members affect the "King Pin Inclination" (Castor Angle) of the rear wheel now swinging in a reduced radius arc? If the caster angle - KPI- goes negative during load will the rear wheel "flutter" like a grocery store shopping cart?
Q2. Does the use of an IRS axle set-up preclude the mounting of the front pivot points on the axle ( which now moves independently) or can they be mounted on a more stable frame member elsewhere Without Upsetting the original "Unsprung Load" Design equation?
Q3.Can the rear wheel axis of rotation be designed so that, at maximum deflection, the KPI never goes negative and maintains at lease 3-5 degrees of positive caster?
Q4. Can a form of the PLSS suspension component be adapted for use as the rear spring element?
Premise #3. The original cable/pulley/chain/sprocket steering had a 30 to 1 ratio with the rear wheel free to rotate, at a minimum, 180 degrees lock-to-lock. While the ratio was reduced so as to make manual ( non-powered) steering possible it also reduced the overreaction by a "novice driver" who might "oversteer" and cause the car to ground loop..
Q1. Can a more effective - power assisted - steering method be devised which retains the rear wheel travel but reduces the effect? Perhaps there could be a "co- steering effort" which would incorporate some limited steering action by the front wheels coordinated with the rear wheel?
Premise #4. The original water cooled, 90hp, Ford flathead V-8 engine might be replaced by a modern straight four, V-4, V-6, or even an air cooled VW "pancake" Type IV engine.
Premise #5. The original vehicle utilized aircraft grade chrome-molly steel I beams perforated with lightening holes to reduce weight.
Q1. Can aluminum be used / Could composite, built-up components be used instead of I beam girders?
Premise #6. The original vehicle was 19 1/2 feet long and approximately 6 feet wide and 6 feet high. The position of the driver was out in front of the front axle. The fuselage was made of metal, wood formers and/or aircraft fabric covered skin. It was designed to accommodate ten (10) passengers plus the driver. The elegant streamlining and the full belly pan were air resistance cheating and resembled the flying craft design envisioned by the inventor.
Q1. Could a two or three place, roadster, run about, sport vehicle body (envelope) be designed and constructed of foam/fiberglas to more modern appearance? The driver/passengers could be situated between the front and rear wheels to provide additional safety. The vehicle need not have "all weather" closed cabin configuration but should retain all the benefits of the unique suspension and maneuverability.