The Artifacts of R. Buckminster Fuller. A Comprehensive Collection of His Designs and Drawings in Four Volumes. Garland Publishing Co. ISBN 0-8240-5082-7 1985. VOL One. pp 97 - 184. FOUND AT THE UNIVERSITY OF TEXAS AT ARLINGTON (TEXAS)
I found this to be the best and most extensive collection of photos, Engineering Drawings and sequential cataloging of the five (5) basic design variations of the DYMAXION Car - three of which were actually constructed - AND drawings of the Tudor Sportster(s) and well as the Kaiser concept vehicle - none of which were built.
Judicious use of a magnifying glass on the fine print and the photo reproductions of the Engineering Drawings gives remarkable insights into the planning and experimentation that accompanied the building and testing of the three prototypes. Most of the Engineering Drawings are labeled "Car # 1 or 2, or 3 or 5" and there are some apparent variations within the design of the "A" frame and leaf spring placement even on the same car.
NOTE: Contrary to various descriptions of the Dymaxion Car as, "... not much heavier than a VW beetle ...(http://www.thirteen.org/bucky/car.html) the Drawing on page 163 of this publication, Labeled DISTRIBUTION of WEIGHT (loaded) shows 4850 lbs with 3450 (71%) on the front wheels and 1400 on the rear wheel. Unfortunately, the photo quality of this Engineering Drawing is poor and, therefore, the EMPTY weight is almost unreadable. (Perhaps 3100 OR 3400 total with 2300 front and 1100 rear???)
The proposed 1943, D-45, Kaiser car - which was never built - shows a drawing with a 960lb projected weight as designed. Architectural and Engineering drawings are always "Stronger and Lighter" than the "as Built versions."
The Dymaxion World of Buckminster Fuller Robert W. Marks, Reinhold Pub. 1960. Library of Congress # 60- 5487. Obtained from Amarillo, Texas Public Library (This seems to be a hardbound copy although there is also a paperback edition with slightly different arrangement of Figures and photographs - the page numbers don't match either.
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, the primary differences were in the design and construction of the sub-frame assemblies which supported the rear wheel. The length, placement of pivot points and the complex castor angles and wheel inclination differ across the three test vehicles.
There were also subtle external features which differed between models 1, 2, and 3. These include the shape and placement of doors and hatches, air scoops and louvers, the number of headlights and the construction of the windshield and side windows.
Driver/operator seating position for all vehicles is in front of the front axle, similar to a modern mini-van placement (VW - Vanegon, Toyota Van, etc.) which use a rear mounted engine/transmission or one placed under the floor.
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 - inward and upward - at the rear wheel pivot support. In the elevation view the girder like structure is straight without a dogleg, upward 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 cross members 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 "A" frame, 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 10 degrees from the vertical 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 (Referred to as Car #5 on p. 158- 59, The Artifacts of R. Buckminster Fuller.) 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 two 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.
Inventions: The Patented Works of R. Buckminster Fuller, St. Martins Press, Inter Library Loan from East Texas State University, Commerce, Texas. This perhaps is the best set of Patent office Drawings - much better than the 300 dpi printouts from the BFI website, which was my first source.
This book contains the complete text of the Patent Application where as, the computerized version has several paragraphs related to the rear suspension OMITTED due to incomplete entry of columnar text appearing above and below drawings.
The Patent Drawings. It is difficult to tell whether this version is the "final" combination of elements tested in the first two vehicles. The "A" arm, rear wheel sub-frame seems to be a compromise between the #1 car (heavy, intrusive, girder like arm) and the shorter, less bulky "A" arm of car #2 (pivot point amidships.)
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 again with a front axle mounted pivot point is shown, 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.
In the final analysis - after reviewing all of the "A" frame designs - ie. overall olength, position of pivot points, angle of the steering post, castor angle and position and type of leaf springs (transverse or longitudinal?) and the various steering mechanisms (non-gear reduced pulleys, angle/bevel gears and worm & wheel) what is the best configuration based on the various designs tested??
There are two sets of drawings labled Car #5. One has the typical, symmetrical "A" frame with a vertical steering post, while the other has an asymmetrical "A" frame with the inclined steering post. Which one was actually used on the last car built is not specified.
It is interesting to note that the pivot point for the "A" frame in this final version is toward the rear of the vehicle - AND, there is no pivot point or axis of rotation at the front axle as noted in the Patent Drawings.
It would seem that Fuller abandoned the "articulated" support of the engine supporting sub- frame and the use of transverse leaf springs opting for two sets of parallel leaf springs and the fifth, rear mounted, transverse leaf spring which supports the "A" frame structure.
Is there any narrative description/explaination of the "final design" which might be found in another source. Perhaps the best source of information would be the Car #3 (Design # 5??) which is in the museum in Reno, NV.