Wood Frame and Skin
One of the alluring design features of this Austin 7 Special is the Birch wood skin that begins at the front of the cockpit and carries through to the boat-tail back end.  I love wood working and this is one of the main reasons I chose this particular design.  

I will use Ash for many of the structural elements of the body frame beginning at the cockpit. The skins will be made from Birch.  I have never planked a wooden boat, but I can presumably follow those proven techniques on this cyclekart.  Most applications; however, use heavy planks which will not be desirable in this application.  Old WWI aircraft employed light wood skins to provide cover and strength and the brief description of this car suggested they used similar techniques.  I have not found planking on aircraft, it appears they use larger flat sheets then steam bend and fasten them to the aircraft frame.  But this does not give the striped, planking appearance of the inspiration car.  I am considering using 4′ x 8′ x 5 mm thick Birch plywood sheets that are ready available at big box store lumber outlets and then marking, engraving, or wood burning the individual slats.  This is something I need to test out.  In the meantime I will research it further.

The Birch skins will be treated to protect it from the elements and give it a little bit of color.  Apparently Birch does not do well in weather, so I will need to do a good job of sealing it thoroughly with either a flat or satin finish.  Do I dare say satin, or is that too shiny?

Front Mounted Engine
The wood skins encapsulating the rear boat-tail presents a significant challenge of how to accommodate all the heat that the typical rear-mounted engine produces.  That would almost certainly have a very adverse affect of splitting and discoloring the wood skins over time.  So I’ll follow the logical solution of mounting the engine up front.  I will use a standard 6.5 HP Predator engine with stronger valve springs, removed governor, and electric motor start.

Drive Shaft/Gear Box
Not liking the idea of a long chain drive between the front mounted engine and the back wheels, I’ve chosen to employ a driveshaft and rear gearbox.  Colin Warnes came up with a design that I will copy.  While it will make the cyclekart heavier, my main motivation is not striving for speed, so I’m OK with the added weight penalty.  Colin’s design appears to work, and he provided enough design detail that I should be able to replicate the parts I need.  I will depart from his design where he employs externally exposed gears to drive his wheels; mine will follow the more traditional internal, centrally located, gear setup.

“A” Frame Chassis
Austin 7’s employ an “A” style chassis that I will copy.  I like the idea of sticking to the original design to the extent possible while still balancing the fact these are caricatures not exact replicas.  The “A” style frame should in theory work out very well.  Rather than the typical 3″ x 1″ rectangular steel design, I am going to use 1-1/2″ square tubing.  I believe it will be strong enough given the design I have in mind. 

Front Axle and Spindles
On this project, I will build my own axle and spindles.  I’ve done a lot of research on the design and components and believe my welding, while not the prettiest, will be more than strong enough.  I am considering moving up to a TIG welder, but that may not be within the time frame or monetary budget constraints.  Besides, I told my wife that last years purchase of a MIG welder would be good for many builds in the future.

Rear Axle
I am teetering on whether to use a solid axle or a Peerless differential axle.  I already own a Peerless differential axle, so there’s a better than even chance that’s the way I will go.  Again, while a little heavier, it makes driving corners so nice.  Since speeding past all my fellow cyclekarters is not my main objective, I’ll be content with a nicer cornering cyclekart as I wave all of you on bye.

Rear Wheel Suspension
The Austin 7 Special rear suspension used quarter elliptic leaf springs, cantilevered from the rear of the chassis.  My “A” style chassis will accommodate this type of setup.  Ideally I’ll be able to come up with a floating configuration, but it will be difficult.  More than likely, I will use an axle that is firmly fixed to the chassis and then use fake leaf springs like I did on my Bugatti.  My Bugatti rear quarter leaf springs faked out many onlookers, so I can easily do the same on this project.

Wheels
I was able to find four very affordable old Honda 90 wheels that will need considerable refurbishment.  Thanks to Kelly Wood’s shared enthusiasm for wheel building, I was able to refurbish one wheel very successfully on my Bugatti, so I am confident of repeating this.  While I like the more authentic looking creations Kelly has recently developed and shared, I am not excited by the associated cost.  I am considering creating 3D printed covers that can screw on the outward face of the Honda hubs to give a simular appearance (from a distance).  If that does not satisfy me, I can always shell out another grand later on if it irks me badly enough.  But I’m OK with the tried and true Honda 90 wheels for now.

Bomber Seat
I love the bomber seat style this race car employs.  There are a lot of YouTube videos on how to build you own either from scratch of via a kit you can buy.  While it may not be the most comfortable design, it certainly matches the time period and of course invokes a WOW-like smile.

Onshape Design
I have moved over to Onshape to conceptualize this design.  My original occupation back in 1978 was design drafting, so I am employing the same elementary techniques with this modern marvel of engineering.  

My design process only considers the overall layout and dimensions for the cyclekart.  One huge advantage Onshape provides me over my old style drafting is it allows me to draw over an imported picture that I scale to fit my parameters.  That ensures I have the right overall size, shape and appropriate placement of the major components.  Once the chassis is built, I then proceed to the engine mounting and body framing.  All other details get figured out on the fly as I go or as I lie down at night before falling asleep.  I truly admire the more advanced designers who take their designs to a full 3D rendition whereby they figure out the loads, assemblies, parts movements, interferences, etc.  Maybe I’ll reach that level of expertise someday, but my old ways blended with this new tool works perfectly for me.