Velomobile in virtual windtunnel

Veloci-velo in virtual wind tunnel at 32 km/hr (20 mph). At this speed the cdA= 0.08, with further tweaking this could be reduced but will do the fine tuning on working prototype using wool tufts and video footage. In combination with lightweight chassis (under 22kg) I hope this velomobile will be competitive in average speed with more performance biased velomobiles such as the DF and the WAW but at a significantly lower cost.

Veloci-velo design philosophy

veloci velomobile ©2018

The design philosophy for this velomobile are low vehicular mass, aerodynamics, ease of manufacture, cost and minimal environmental impact.

Main benefits are...

• Non-polluting - 65% of all carbon monoxide emitted into the environmental is from road vehicles.   Veloci-velo is a Zero Emission Vehicle.
• Healthy and Fun - Easier than riding a bike, get fit commuting, shopping or just out cruising.
• Easy to park and store - Requires no wall or object to lean it against, takes up less than 1/6 loadspace of average automobile.
• Secure and safe - Stable and nimble tadpole trike design. Built in frontal crumple zone.

To understand my vision you really need to understand the problem...
The problem with most of todays personal transport options comes down to one thing - MASS!
Everyday 66% of vehicle journeys are under 6km in distance are taken by just one person!
This seems incredible especially when drawn to the fact that the single occupant only makes up 2-8% of the total mass being transported. So why do we need a 1000+ kg machine to transport one person such short distances? Is it for convenience sake?

Common chassis open or enclosed wheels

The great thing about designing my own velomobile is that I can have one of two options for the bodyshell. I can have an open wheel design like the one on the left or an enclosed version on the right. Both use the same chassis. The advantage for speed goes with the enclosed version, but style and practicality the winner has to be the open wheel design velomobile. What's your favourite?

Noise inside a velomobile

From my experience in riding velomobiles I have found one of the most irritating aspects to be the amount of noise (rumbling) when inside a moving velomobile. All this noise adds up to rider fatigue and makes the velomobile annoying to use when compared to a diamond frame bicycle.

Commercial fiberglass or carbon fibre monocoques are hollow tubes that echo like a drum with all the drivetrain and road on tyre noise as well as the suspension noise being transmitted to the rider.

Quest Velomobile Fiberglass Monocoque 

Solutions? I really like the foam shells of John Tetz the only issue with this construction method is the labour involved and the shell only provides limited crash worthiness. But it is lightweight and noise would be minimal due to the sound absorbing properties of the foam.

John Tetz Foamshell

Another great design is this Softshell concept velomobile has been made by Czech designer Martin Miklica. This approach would mitigate noise but if the fabric is too tight it may cause a drum effect.

Martin Miklica Softshell

Of course there are other solutions such as used in the car industry such as acoustic soundproofing, rubber mounted sub chassis etc. etc. but this approach always adds weight which is undesirable in a velomobile. Maybe even an approach of using all three of the above for one design could be a way of making riding a velomobile a quieter experience?

Quality renders of open wheel velomobile

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".

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

Wheels out velomobile

Here is a render with exposed wheels on Veloci Velomobile. Advantages of this design is the ability of  a tighter turning circle and ease of changing a tyre. I like the look of such velomobiles with the only downside being loss of aerodynamic efficiency (this would be quite small).

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 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 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.

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...

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

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!

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.

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.