Let us review the human powered commuter vehicle criteria
that were the requirements for the design of the EcoVia.
1.
Weather Protection
2.
Statically Stable
3.
Reasonable Cruise Speed
4.
Cargo Carrying Capacity
5.
No Wider than a Bicycle
6.
Same Height as an Auto
7.
Comfortable posture and ease of entry
8.
Two-wheel drive
9.
Car-type Wheels
10.
Electric Assist for Hills
The first two posts on the design of the EcoVia can be found below
and here
The first two posts on the design of the EcoVia can be found below
and here
The completion of the faring essentially brings the EcoVia
Mk1 project to a close. In this post, I will discuss the construction of the
faring and reflect on how well the design criteria were met, comparing the
EcoVia to the yardstick for commuter vehicles, the Pedicar.
The foundation of the faring was a lozenge shaped rectangle
of ½” dia. cro-mo tubing. This rectangle is orientated parallel to the ground.
The front of the rectangle screwed on both sides to a framework that attached
to the trike chassis. Pivoting around the axis formed by the two screws allowed
the faring to tilt forward for rider access. Attached at the front of the
cro-mo rectangle was a smaller vertical rectangle of 3/8” dia. cro-mo tubing.
This is where the nose cone attached
The nose cone was made from EPS insulation foam, five 2”
sheets glued together and formed to the correct shape. The final shape was coated
with Styrocoat to form a hard-protective shell. The back surface of the nose
cone was glued to a 1/16” thick sheet of polycarb and the polycarb was in turn
screwed the vertical portion of the cro-mo frame.
The skeleton of the faring was made from ½”x 1/8” soft
aluminum strips screwed to the cro-mo frame and pop-riveted to each other. ¼” x
1/8” aluminum strips were used between the larger strips.
The two sagittal strips along the top of the framework are
spaced about 10” apart. With the nose cone removed, a rectangle of double-stretch
fabric wrapped around the cro-mo frame tube at its bottom and the aluminum
strips at the front, back and top. The fabric was sewn in place with Kevlar
thread. The fabric was Spandura, which in addition to being double-stretch that
could be made water repellant with a spray like ScotchGuard.
Screwed to the framework along the faring top between the
fabric strips and behind the nose cone was a polycarb strip. Behind the nose
cone the strip was left clear. Around the rider’s head the strip stopped to
allow for a polycarb windscreen. A second polycarb strip continued behind the
riders head. A third polycarb strip enclosed the back of the faring and was
hinged at the top to allow opening and access to the luggage compartment. This
hatch was held closed by a magnet screwed to the framework.
Wireless turn signals were mounted behind the front window
facing forward and at the top behind the rider’s head facing backward.
The front turn signal is shown above.
A wireless speedometer was attached to the inside of the
windscreen along with the turn-signal controls.
Rear view mirrors, which really didn’t work very well were
bolted to the framework through the fabric.
The weight of the entire vehicle was 83#. The weight of the
faring, without the front mounting bracketry and rear faring support, was 16#.
Of course, the nagging question was how would the faring improve cruise speed of the EcoVia? In an attempt to assess that objectively, I spent two weekends doing four test rides over a 6 mile stretch of road that, except for one gradual downhill, was essentially flat. Three of the rides were without the faring to familiarize myself with riding behavior and the fourth was with the faring in place.
I must say up front that I no longer ride recumbents but
instead ride an upright mountain bike. I never could go as fast on a recumbent
as an upright, despite 21 years of riding an Avatar 2000.
I noted two speeds from each run. One was a speed past a
traffic monitor set up to advice motorists of their speed that I encountered
early in the ride. I had routine readings on an upright of between 17 and 19
mph. The second speed was the average for the entire six mile run.
Without the faring the speed past the speed monitor was
17mph and the average over the six miles was 14mph.
With the faring the corresponding speeds were 20 and 16mph
respectively.
Needless to say, the speed increase with the faring was
unexpectedly low, despite the faring appearing relatively streamlined.
Three reasons for the low improvement come to mind. One is the
added drag from the flow under the faring, since its bottom is open. The second
is that mechanical losses from all the drive components dominated the
aerodynamic losses. The last is that a vehicle as high as the EcoVia has a large cross-sectional area than typical streamlined vehicles, even though its width approximates that of a bicyce.
The day I used the faring was a chilly 40deg F and the space
within the faring was comfortably warmer that the outside with only my face and
neck feeling the chill.
So against the original design criteria and compared to the
Pedicar (below), how did the EcoVia fare?
1.
Weather Protection: Assuming the fabric was
sprayed with ScotchGuard, only the riders head is exposed to moisture.
Internally the wheels were covered with fenders. So like the Pedicar the EV
provides weather protection.
2.
Statically Stable: The EV has a lean-lock to
make it statically stable and the Pedicar is naturally so.
3.
Reasonable Cruise Speed: I feel the EV fall
short here, at least with me riding it. The 16mph average should be closer to
20mph. The Pedicar had a 15mph cruise speed.
4.
Cargo
Carrying Capacity: Currently the EV has about a 2cu.ft. cargo capacity which
could easily be increased to 3cu.ft. The Pedicar easily has twice that.
5.
No Wider than a Bicycle: The EV has a width of
28” and the Pedicar 38”.
6.
Same Height as an Auto: Both the EV and the
Pedicar meet this criterion.
7.
Comfortable Posture and Ease of Entry: Again
both vehicles satisfy this criterion.
8.
Two-wheel Drive: Both vehicles satisfy this
criterion.
9.
Car Type Wheels: The EVs wheels can be removed
with one screw. They are all the same and it carries a spare. It is not clear
how the one would remove the Pedicar’s wheels.
10.
Electric Assist on Hills: Attempts to add
electric assist to the EV have been put on hold indefinitely because the electrical
engineer assisting me had more important obligations. Two attempts to develop a
motor controller were unsuccessful. Only a small fraction of the motor’s 600
Watt potential were delivered by the batteries. The Pedicar has no electric
assist.
I would say the EcoVia met seven of the 10 criteria. Bumping
up the cargo capacity to 4cu.ft. should be straight forward. Bringing the
cruise speed up to 20mph appears to be a lot more difficult.
With the addition of the faring it was difficult to get the support foot back to the ground after unsuccessful launches. The presence of structure and the narrow width of the faring inhibited getting a foot back on the ground. Several painful crashes ensued during unsuccessful launches.
So successful launches with the faring required the use of the lean lock. Below, the disk brake that acted as the lean-lock for the EV.
When the lean lock is engaged the vehicle is like any other
statically-stable tricycle. The level of static stability is therefore a
function of the c.g. height, the track width and the load distribution of the
wheels.
Engaging the lean lock also makes climbing slow-steep hills
much easier. You don’t have to waste energy and concentration on trying to
balance the vehicle at very low speeds, which is where balance is poorest.
So for the EcoVia Mk2 I will be lowering the seat height
from 24” to 20” and increasing the track from 20” to 24” to improve static
stability when the lean-lock is engaged. The other improvement will be pivoting
the faring at the back instead of the front to eliminate the weight and the
foot interference produced by the faring-support structure around the front
wheel.
Below is the EV with the seat height reduced about 4”. Compare this to the second picture in the post.
I do take hope in the success of the Velotilt design. While the Velotilt drives the front wheel instead of both rear wheels it is the design that is most similar to the EV.
a.
An 11 x 1
drive will replace the two-stage 7 x 3 system with it twin bottom brackets.
b.
The structure for front faring pivoting will be
eliminated.
c.
The Soft-Ride-type seat suspension will be eliminated
in favor of a mountain-bike shock connected to a link that holds the linkage
that synchronizes the pivoting wheel beams. This will remove one large frame
tube
d.
Hydraulic disk brakes will eliminate the brake
synchronization linkage that allows one lever to activate both rear brakes.
e.
Tube size and gauge will be optimized and not
overdesigned as is currently the case.
So I consider the EcoVia Mk1 to be a successful
proof-of-concept of a two-wheel-drive tilting trike, but much must be improved
in production prototype.
Hephaestus
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