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.

Velomobile - Photorealistic of Veloci

Veloci-velo as a photorealistic scene

Velomobile Plans

Now that I have finished the design phase. It is now time that I got on with building Veloci-velo!
I sent the unfolding file to a large format printer to get printed out at 1:1 scale. At this size the coroplast needs to cut out the bodyshell is only two sheets which equates to about 2kg which is what I calculated and hopefully will keep the total weight of Veloci-velo below 22kg (48 pounds).

Plans at 1:1 coming out of the printer.

Here is a image of the plans with the 'mule' chassis in position on the floor plan.

High Quality Veloci-velo renders

In a moment of spare time while designing the chassis and suspension, I decided to render a few high quality images of Veloci-velo in it's final format. Design changes include a larger entry/exit hole and wider at the riders shoulders. I hope to have some more info on the chassis soon and get building!!!

LHS

RHS

Rendering and Unfolding of the bodyshell

I am happy with the final shape and the Cd factor of this shape. Have unfolded it now to cut out to make 1/10th size model and then I will make a 1/4 size to sort out any small problems.

Aero tests continued

Last post I had a result that provided a cdA of 0.027. Unfortunately this result was wrong and after more testing I would have to put that result down to a glitch in the system.
Anyway I really liked the look of that particular shape which also allows more shoulder room for the rider. I ran the new tests after calibrating the software against a shape with a known Cd ( a sphere = 0.5). The new shape came back of a best of Cd=0.18 and with a slightly smaller frontal area of 0.44m2 with calculates to a CdA of 0.792 which is pretty good for a shape that can be produced using corflute/coroplast.

Veloci velomobile CdA=0.792

Veloci velomobile in virtual windtunnel

I am very happy with this shape now and the chassis design is going very well. I considered buying a KMX kart to use as a chassis but there were three things that I didn't like about these trikes...

1. Quite heavy at 19kg
2. Wheelbase not quite long enough
3. No suspension

KMX Karts are great value however and a fine product and would be suitable for a low cost velomobile. I will be building my own chassis this winter and hope to have Veloci-velo ready for Spring.

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 aerodynamics final design

After re-drawing the bodyshell to fit the exact dimensions required I have found that the CdA figure has dropped to 0.081 Here is a few images of latest and final renderings before I make a full size working prototype.

This is a great result as I had thought that anything 0.10 or less would be adequate. My goals for the design have been reached with the low drag co-efficient, the low weight due to the construction in coroplast/corflute and I think I have achieved a a good looking design which is important for consumer acceptance.

I have been reading a lot about vehicle & chassis design and one thing really stood out to me was the way the automobile industry goes about designing a new vehicle as they take a very different approach.
Their most important criteria is asthetics. This is a basic overview of the design process...

1. Draw-up concepts
2. Choose a concept
3. Refine the concept
4. Larger scale concept produced concept adjusted to fit people and parts
5. Adjustments made to fit chassis platform and suspension
6. Body changes for aerodynamics
7. Prototypes built andtested, changes made
8. Production readying

Again the auto industry starts by defining the design by its appearance, designing a velomobile in such a way would lead to a vehicle that would not perform as expected. The design process for a velomobile and indeed Veloci-velomobile has been...

1. Application definition - lightweight, aerodynamic, single occupant, human powered vehicle
2. Chassis and suspension design - lightweight, stiff, independent suspension
3. Aerodynamically designed to envelop rider and chassis - again lightweight
4. Development of the entire design to make it user friendly and asthetically pleasing

So the design process is quite the opposite to the auto industry approach, I think I have achieved my goals in this design. Please feel free to comment.

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!

Velomobile safety and drag co-efficient

There has been a few cases of late of cyclist being hit by cars with major injuries or death being the result. I still think it prudent that some sort of passive safety is designed into Veloci Velomobile. I really like the construction method used on the eco-car TREV It is lightweight, reasonably easy to construct but very strong and with the foam as a core would have some energy absorbing capacity.
For Veloci Velomobile I will design a semi-monocoque with the monocoque being where the rider sits while the suspensions and crank boom are attached to the monocoque. I believe this would be the best approach to keeping it lightweight and having some crash/impact protection.

In addition to the crash protection of Veloci Velomobile I have been redesigning the bodyshell to make it a little more slippery and make the forward vision for the rider a lot better. I now have the Cd figure down to 0.20 thus the CdA= 0.45 x 0.20 = 0.09 which is really good and better than the Quest velomobile now. 

Veloci Velomobile drag co-efficient now 0.20

June 2013 Veloci Velomobile latest shape rendering

Velomobile Design Considerations

Quest Velomobile. The ultimate velomobile?

Part of the design process is considering what and how a product will be used. Like all good designs a set of criteria is needed. My criteria for a human powered vehicle are as follows...

LOW MASS - Must be under 22kg, more mass means more power to accelerate and push up hills. Ideally I would like to get the weight down below 20kg. This will be achieved by building Veloci with a separate chassis/body shell. The body shell will be made of coroplast/coreflute - a flexible but lightweight material while the chassis will be large diameter aluminium tubing.
AERODYNAMIC - What is the use of having a bodyshell (mass) if it is not aerodynamic! The Quest Velomobileis seen as the ultimate in this respect but again the Quest weighs in at 30+kg. The design of Veloci will have a small frontal area as well as an aerodynamic shape, maybe not as slick as a Quest but again it won't be as heavy and will have a smaller frontal area which should counteract this fact.
FULL SUSPENSION - Suspension is a must on velomobiles. Suspension must allow maximum grip for the narrow bicycle type tyres and absorb power robbing "road buzz".
LOWER COST - Current Velomobiles are expensive. One of my aims is to lower the cost of buying such a machine. Simple elegant design will help achieve this goal.
I have already made up a prototype chassis which will test dimensions and suspension geometry. The bodyshell is still under development but on the website you can see 3D renderings I have done which is very close to the final shape and proportions.