Streamliner tail box for the steel tandem

Hello folks,

It's a long time since the last posting, so here is an update:
To find out, how the numerous 3d-sketches will look in reality, I've scrapped the old ugly rear box of the steel tandem and build a new tail with a more sophisticated shape and enclosed rear wheel wells.
To reduce the increase in weight, the drivers seats are now an integral part of the tail box.
With this much more massive body, the weight is just 4kg/8pounds higher than before.
For a racing velomobile this would be a catastrophe, but for a cargo-tandem like this it's acceptable.
I have used 4mm birch plywood, except the sides, which are pine (left over from an abandoned project)

structurally integrated bench

internal partition with wheel wells

top panel is on

A look in the trunk, childs backrest not in place

My first test drivers

the attached retro rear lights 

Although it looks really wide, it's just 119cm/3 ft, 10inches in width.

The entire box is attached to the frame via 4 bolts and can be easily removed if maintenance or repair is necessary.

There is not enough space to make any repair on the wheels or even to adjust the derailleur or brakes, as long they are inside the wells, so easy removing is essential.

We have driven 100km since the modification and are very happy with the new tail.

It provides a lot of space behind the backseat (ca. 100 litres/ 4 cu.ft.), our childs are much more protected from the airstream than before, it's rock solid and looks way better, so the pluses outweights the few drawbacks in our opinion.

Next building projects are a front hood and a light soft top to make it a fully faired retro pedal car.

I had made a paper model two years ago, which I had given a pointy nose, instead of the more blunt front of the CAD designs:

Pointy front

Pic from previous post for comparison

Which looks better in Your opinion ???

Kai

More improvements of the design

Here is my latest sketch.
It shows the convertible top version with the childs backseat and luggage space behind.

 

 

 

As shown below, the luggage space of the convertible is around 90litre/3,17cubic feet, the space for the childs has twice the volume.

 The translucent bodys represents the space provided for childs and grocery.

With a disassembled backseat the space in the rear is around 270litre/10 cubic feet.
 

 

The same partition of the space behind is also possible with the formerly shown Kamm tail.
 

 

Kai

 

CAD design #2 in three versions

I changed the lines and measurements of the previous design slightly,
the most important as follows:

Bottom bracket height: 40cm/16"
Seat height: 20cm/8"
Backrest angle: 40° from horizontal
Min. distance heel to ground: 7,5cm/3"
Car body height at crank position: 75cm/30"
Car body height at knee position 80cm/32"
Maximum height of soft top: 105cm/42"
Width: 120cm/47"
Length: 320cm/126"
Wheel base: 210cm/83"
Ground clearance: 12cm/5"
Weight: around 60kg/130lbs (with two drivetrains)

Here are three different versions of my pedal car.
It's basically the same car body with different rear versions, which can be simply attached to the tail.

 

Basic car

 



 

The convertible

 

 

 

The Kamm tail

 

 

 

The pickup

 

 

 

There's still some work to do on the front, which has to be changed.

 

 

Kai

 

 

The monocoque in 3D CAD

Did I mention that I want to make the tandem fully faired?
For the first time a non stressed fairing attached to the frame, a further development could be a rigid, frameless monocoque.

To find the desired retro design I prefer, I have played around a bit with SketchUp.
Although I'm not a big fan of CAD, it's useful to see a planned design from different angles before the build starts.
I confess I'm not a skilled CAD designer, but hope to improve my abilities soon.

 Lenght: 320cm/126 inches

 Width: 120cm/48 inches

Height is 105cm, maybe I have to raise the roof a little bit



SketchUp is a rather simple program.
It's easy to use but has just a few tools.
For example the step at the bodys edges should be a 45 degree bevel, but I haven't found the necessary tool.
Furthermore I wanted the front and rear end of the body a bit narrower, but I wasn't able to alter the body of my pedal car that way.

The build will be done with 4mm gaboon plywood ( as the blog name suggests) and epoxy as a stitch&glue project.

By the way, here are the newest parts for the sociable:

Front wheels with 90mm SA drums and one rear wheel with Nuvinci N360

The second rear wheel is fitted with the Alfine11.

I can't decide wich hub is better for our needs, we have to find it out while riding :)

Kai

Tandem Videos

Here are two movies, which shows the maneuverability and speed capability of our tandem.

 

 

I'm still trying out the new action cam, hope to improve my skills in making short movies.

Surely a few more vids will follow the next weeks.

Kai

Ruegen vacation

We travelled to Rügen island on the Baltic Sea this year, for just one week.
The bed of our truck was full of childs bicycles, a big tent, camping stuff and the tandem.
Weather was perfect, not too hot and our camping ground was just 100m away from the beach.
Our childs were most interested in playing on the beach and swimming in the waves.

 I'm proudly present  my self build "Pyramides of Gizeh".
The scale was slightly different from the original and they were washed away after two days, because the "Nile" was on high tide.


We managed to left the car in the parking lot and used the tandem and bicycles instead, to make the way to the nearby market.
Cape Arcona with it's  two lighthouses was just 4 or 5km away and thus a nice reason for a bicycle tour.
As you can imagine, we got a lot of positive attention and friendly comments about our tandem.

Cape Arcona

Harbor of Vitt

In some cases the bicycle paths were too narrow to drive on with a 1,2m/4ft wide sociable, especially the very beautyful path on the northern shore of the Wittow peninsula, wich I had driven on last year with my one tracked Peer Gynt recumbent.

And these roads with two separated track stripes, which are not a problem for a normal car, were sometimes a little bit tricky to drive with the tandem, because the small rear track is just 5-10cm/2-4inches wider than the grass stripe in between.
It was very difficult to keep both rear wheels on their track stripes.

Our over all distance we had cycled during vacation was just 60km.
Not THAT much, but child friendly.

Kai

Now the inspection hatches

Over the last days I had no time to work on the frame.
But since yesterday I have completed the four inspection hatches.
These parts are important for several reasons:
When installing the axle connectors, I have to work from the inside of the boxes.
(Drilling holes, tighten screws and so on.)
I want to protect the inside of the boxes with linseed oil.
Furthermore I want to use the boxes for stowing my gear, while underway.

The making of the hatches are pretty easy, although a little bit time consuming.
At first I mark the respective hatch form on the surface.
Then I have cutted it out with the jigsaw.
The next step was the making of edge reinforcement frames, 1 1/2 inches wide.
These frames are oversized at the outer edge and undersized at the inner.
The trick is, to make no exactly round hatches, because then it's difficult to get the frames inside the hole as one part.

Here you can see one of this frames glued in place.

Many woodworkers used to say, it's impossible to own too many clamps.

They're right!

The three hatches in the seat box.

The cutted out parts back in place

 

New and old frame

 side by side

 

Kai