Final wheels out design

Decided to go with wheels out design, More practical and only slightly less aerodynamic (plus it looks cooler).

Open wheel Velomobile

On my previous post "F1 inspiration" I tested a open wheel design which surprised me with it's aero efficiency. I decided to model this up a bit more in detail with some of the renders below.

What I really like about this design is its simplicity, ease of construction and ingress and egress would be very much easier than a wheels in design.

I can see many benefits especially I think this type of velomobile design would be more accepted by the general public as still being a "bicycle".

Simplify and add lightness

Colin Chapman's quote "Simplify and add lightness" should be the catch-cry of anyone designing a velomobile or human powered vehicle. One of my favourite designs which has been designed along this mantra is Bob Stuarts Car-Cycle X-4 https://microship.com/bob-stuart/

This is a fine example of integration of parts to make a simpler vehicle. The use of different materials such as fibreglass for the chassis and coroplast for the body is using the correct material for the job. The fibreglass chassis incorporated the hinges for suspension so in fact the chassis IS the suspension. The coroplast body is tough and resilient to bumps and knocks as well as being lightweight.

Another consideration I see in this design is the cost factor with no real "exotic" materials used.
Too often Carbon fiber is seen as a miracle material and used inappropriately or used in a way that does not utilise its specific properties (i.e.. stiffness with low weight). Read about this wonderful vehicle from the link above.

Practical City Velomobile

I see a need for a velomobile that can integrate well with city traffic. This would mean a higher seat height and room for a child and/or groceries in the back. Again the design must be lightweight and aerodynamic. I really like the Mochet Velocars of the 20's, 30's and 40's . Below is what I see as a possibility.

Length = 2400mm   Width = 1000mm   Height = 1050mm  Weight = 45kg

Electric assist on velomobiles

After about six months of no progress due to building a new home I have finally got my workshop back and will be starting work on Veloci-velomobile once again.

In this time of limbo I have thought about having electric assist on  a velomobile and came to the conclusion that it would be advantages to have such a system.
Advantages would be...

• Faster acceleration from standstill and rolling acceleration
• Easier climbing of hills

From reading reviews of various systems including hub motors, mid-drive and direct drive I believe that a mid-drive system would be best due to the fact it will use the gearing already in the bike. I really like the 8fun system which can be configured with different power outputs to suit regulations. Most common is 250W (Australia & Europe) 300W (New Zealand) and 750W (USA).

Even with 250W the acceleration would be quite impressive and with the aerodynamic advantage of Veloci-velo top speeds would/could  be..

• 250W = 75 km/hr (46 mph)
• 300W = 82 km/hr (50 mph)
• 750W = 120km/hr  (74 mph)

When designing Veloci-velo the design brief was to have a vehicle that could maintain 40km/hr for the average rider so the electric assist needs to be no more than 300W and geared to provide the best acceleration up to the 40 km/hr limit.

See table below...

Velomobile - Photorealistic of Veloci

Veloci-velo as a photorealistic scene

Semi-monocoque velomobile

Final render of velomobile semi-monocoque to be manufactured from plywood. The render does not include a few cut-outs for other components. I hope to get the final weight of this component down to less than 5 kilograms. This final design allows a 'safety capsule' around the rider a feature that I really wanted to have. Making from plywood makes an easy build and the possibility of a true 'flat pack' kitset velomobile. I am exploring the possibility of this being a Open Source Velomobile as this may lead to faster development once the basic design has been done.

©2016 James McLeod

Semi-monocoque velomobile

Final render of velomobile semi-monocoque to be manufactured from plywood. The render does not include a few cut-outs for other components. I hope to get the final weight of this component down to less than 5 kilograms. This final design allows a 'safety capsule' around the rider a feature that I really wanted to have. Making from plywood makes an easy build and the possibility of a true 'flat pack' kitset velomobile. I am exploring the possibility of this being a Open Source Velomobile as this may lead to faster development once the basic design has been done.

©2016 James McLeod

Velomobile front beam suspension design

Most commercially availible velomobiles feature Macpherson Strut independent front suspension. A popular choice for full monocoque designs.

Tadpole design three wheeelers require roll stiffness at the front because the single rear does not have anti-roll stiffness so suspensions have to be correspondingly stiff to reduce body roll.
I intend to have a very simple beam front suspension with the advantages being...

• Simplicity
• No track variance when bumps encountered (zero scrub)
• Can be made lightweight (for velomobile applications)
• Great roll stiffness

The beam axle can be mounted to the monocoque section using four elastomers which will be the spring and damper all in one. The benefit of this is that the elastomer will provide vibration isolation and reduce the "road buzz" to the occupant. This isolation reduces the fatigue on the occupant.

Go to this link to see a an arguement for a beam axle front Vs Macpherson Strut.

Semi-monocoque velomobile chassis

Still fine tuning the monocoque design.

Will prototype full size out of plywood to test size and rigidity of design. Enough computer work!

Velomobile Chassis monocoque

Semi- monocoque design for Veloci-velo.
Sub frames for front and rear yet to be finalised. This design is really the best compromise for crash protection Vs weight.

Velomobile in Virtual Wind tunnel

Since I have established the final shape which now has a larger opening and is wider at the shoulders to accomodate the rider. I thought I better re-run the final shape in the virtual windtunnel to get an idea on how aerodynamic the shape is.

The results surprised me a little with the figures coming back at a Cd factor of 0.20 at a velocity of 11.2 m/s or 40kph. This was excellent as I was expecting the Cd figure to be a little higher with these changes. Now with a frontal area of 0.35m2 the CdA is now 0.07!

This final design is the result of appox. 200 hours testing and tweaking in the virtual windtunnel. I am confident that the figures are pretty close as I have calibrated the results against shapes of a known Cd figure.

Veloci-velo Velomobile 2014©

Power required to have a velocity of 40kph is a very achievable (for the majority of people) 122 watts.

see below...

Safety capsule/monocoque

One of my design criteria is to make this velomobile as safe as possible. If a velomobile is too be used on the same roads as automobiles some degree of crash protection has to designed into the vehicle. My plan is to have a monocoque seat/safety capsule. I have been designing a few different types and so far this is what I have come up with...

Veloci-velo safety capsule ©2014

The integrated seat will save on weight. I will construct a few test models out of card to check for strength etc. With the rest of the bodyshell, front frame and rear swingarm attached to this monocoque construction.

Velomobile Frontal area

I finally have measured the frontal area of the new shape and the result has been good as the frontal area for this new shape is 0.36m2.

Calculating the CdA is now 0.36 x 0.21 (Cd) = 0.0756 CdA.
I can calculate using this excellent calculator power outputs and speeds for Veloci-velomobile. The graph below shows that for a modest 150W of power  a speed of  approx. 46 km/hr can be attained. I used 150W because this is what a untrained but fit cyclist could acheive for any length of time.

I also found that smoothing my final shape did not make any real difference to the Cd factor, at the most  it would have changed it by 0.1 so it is best to leave it as is. Now to build the models and then the real thing!

Aero Revelations

I have recently read an article on Mercedes-Benz modelling a car on a animal called the Box Fish. This fish has a remarkable ability to swim in very turbulent currents. Mercedes-Benz then took the basic shape of a Box Fish and built a car which then has a Cd of 0.19 which is very impressive for such a boxy looking vehicle.

I thought I would give this a try on the model on Veloci-velo with startling results.

The previous best cDA figure I achieved was 0.081

Re-modelled "Box Fish" shape cDA= 0.027 !!!

I could not believe it so I ran three separate tests and all tests came back with the same result!

This is quite a reduction in drag and would make Veloci-Velo and very fast velomobile.

I am conducting more tests and calibrating with objects of known Cd factors, More to come on this!

Velomobile Kit? or Retro-fit?

With the Veloci Velomobile method of body construction it will possible to scale it to fit a wide range of different recumbent trike chassis.

This is already been done by other manufacturers with the Borealis velomobile as well as the Ocean Challenger .These are both fine examples of fitting bodyshells to existing recumbent trikes. The drawback is that they are quite heavy (32-36kg) and still relatively expensive.

Veloci Velomobile would weigh in at 20-23kg depending on the trike used as the chassis. This would be a great option for someone who already owns a trike and wants to have a cost effective way of converting their recumbent trike to a velomobile. The estimated cost for a retrofit to an existing trike chassis would be $US = 1000 or Euro = 780.

This is only one option as a custom designed chassis would have less compromises and maybe even be lighter! I have built three recumbent trikes - two with rear suspension, with the lightest being 13.5kg and the others 15-17kg so in theory Veloci Velomobile could be as light as 18-20kg complete!