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

A first mockup

The top panel is cutted out now and loosely screwed to the frame.
I have to install several parts inside the frame,
thus the top needs to be removeable for the next days.

To raise up my motivation I have made a quick mockup.
Very crude, I just leaned four wheels against the frame and the designed ground clearance was provided by my old battery charger and a toolbox under the frame bottom.

Wheel size is 24'' all around

The narrow track of the front wheels will be widened to 110cm/44''

 when the axle will be installed 

The two beams behind the front wheels will take up the bottom brackets and cranks

First "test ride"

Amelie on the back seat

So long...

Kai

Side boxes

Today I have build the side boxes.

 

At first I have made four plywood frames from 18mm(3/4'')birch ply, stacked them together and sanded the pieces to an exact equal shape with the belt sander.

The two frames of the left box are glued and screwed in place

Finally the framework is covered with the usual 4mm ply.

Needs still some sanding.

 

 

Kai

 

The frame takes shape

Todays progress:

The spacers between the beam panels installed

Side view, front is left

All side panels assembled.

The small sheet on the top was a torque test on the fly.

While the frame has still a lot of twist without the top side,

 the frame becomes very stiff with the panel screwed on .



Today I decided to give the side boxes a curved design too.
Just a rectangular box looks really stupid and doesn't fit visually to the curvature of the frame.
Furthermore it adds weight, air resistance and a sharp edge 12cm/5" above the ground behind the ankles and heels of the pedallers is not what I want. (Ouch)
I don't want to explain this further, a picture is worth a thousand words.
I hope to get the boxes ready this week and that the look it will have, is at least a little surprise.

Kai

The plywood frame, first steps

After three days of part time work on the plywood frame I want to show you the results.

At first I have build the four vertical sides of the two beams.
You can see these parts (2,4m/8ft long) leaning against the fence.
I used 4mm exterior birch ply and 20x20mm stringers.
It was a little bit tricky to bend the stringers around the curved edges of the panels, while I have to glue and screw simultaneously, 20mm stringers are real stiff.

Then I spend one day with cutting out the bottom panel, marking all the necessary lines and hundrets of points for screw holes, which must be drilled afterwards.
But it's more comfortable to drill all these holes before assembling and makes the build much quicker.

Yesterday two (inner) beam sides were fastened to the bottom.
Several bulkheads and frames are mainly done now.
Now the frame is 3D but I estimate 50% of work is left to do.
In the picture the frame can be seen from the front and right side up.
The bottom is cutted out, where the glue bottle is standing.
This gives the necessary room for the legs of the two pedallers.
The "wings" on the sides are the bottom of the boxes, which will doubleact as side part of the seat bench and swing arm support for the rear wheels.

Next working steps will be the completion of all eight bulkheads and the supports for bottom brackets and rear swing arms.
Then finally the outward sides of the two beams, the top panel from 6mm okoume and the side boxes will complete the frame.

Kai





 

Sunday ride with a new bicycle

Hello again
At first sorry, that I can't tell you something new about the building process of the new frame.
The building of the frame has been delayed by the very long winter.
Even more than two weeks after equinox we have patches of snow all around.
In my backyard I have shoveled a hill of snow that is now two meters high.
Because of the fine gravel surface I had made last summer in my backyard, the snow was mixed a bit with the gravel while I shoveled it away.
When the sun shines over the last days, the white snow is reflecting most of the sun heat.
But the small gravel pebbles are absorbing the energy, heating up, melting their way down through the snow and forming bizarre structures.

Today we have choosen to make our sunday bicycle tour with our (more) normal bikes.
I have driven my old Peer Gynt with the trailer.
We made a coffee break at the nearby playground, time for the kids to play around a bit.

Last week I have purchased a racing bicycle for my wife, fitted with a Nuvinci N360, wich was proudly driven by my ten year old daughter.

Despite the frame is a bit too small for me, I have driven it on my way to work on friday, just to try it out.
I found out, I will have to exchange the rear sprocket by a larger one, because climbing up hills is a real pain.
Furthermore the longest gear is not driveable with a reasonable cadence, unless I would be able to drive at a speed of 30mph.
But the larger sprocket is just a small improvement.
The Nuvinci is a ingenious example of what is possible nowadays.
I want to test the Shimano Alfine too, but more on this later.
My plan is, that one of both gear hubs will be part of the drivetrain of the new tandem. 

Kai

First rollout 2013, spring is near!

After the snow chaos the last few weeks the sun shines today and the streets are mainly dry.
The tandem has a dusty (and rusty) look after several months in the garage.
Today we have made the first real tour this year, but the snow is still everywhere.
Our normal tour through the nearby forest is not possible, because the small forest roads are still covered in snow.
So we can only drive on public roads, without the sunshine it becomes quickly cold.

Just 9km on the tandem today.
We are waiting for warmer weather.

Best regards
Kai