The Orion Speedtrike By Raymond Gage

Orion Speedtrike

Trike Construction By Raymond Gage
Latest Trike Fairings Frame 2 Integration CasaGrande


Orion SpeedTrike Sponsors


Introduction: 
At the recent World Human Powered Speed Challenge (WHPSC), 2004 edition, I had my first chance to try out the chassis for a speedtrike design that I have had floating around for almost 15 years. The concept is to make a fully faired tricycle human powered vehicle (HPV) designed for high speed, and specifically to compete for prizes being offered for record speed through 200 meters with flying start (the .deciMach Prize) and distance covered in one hour (Dempsey-MacCready Prize).

When I was at the WHPSC ’04 event, held outside of Battle Mountain, Nevada, I was a little surprised by the amount of interest people have shown in my project. I have even been contacted by people who have seen only an early rendering of the project as it appears in the WISIL screensaver. I am excited by the design, and because other people seem to be as well, I thought I would try to keep some info and progress reports on the WISIL site, which Warren Beauchamp has very graciously offered to host, “as long as I promise to keep working on it!” Please consider this write-up to be my “official” promise!

You can click on most of the images on this page for a higher resolution view.

The Concept:
The concept behind the trike is to try and combine the stability of the three wheel design with the low drag of a two wheeled low racer. Two this end, I have come up with a single driven and steered wheel in front, similar to several successful two wheeled speedbikes, but with two non-driven and non-steered wheels mounted on a wide outrigger (which I call the wing) in the rear. Note that while the fairing is not a true surface of revolution, it is derived from one, which should have lower drag than an extruded surface. This is because the revolved surface has less skin area in the turbulent region than the extruded one, a very important factor when you are trying to achieve laminar flow over ~60 % of your length. Also, the revolved surface allows a more direct path for the air from nose to tail than a typical extruded type design The fairing is symmetrical top and bottom so as to half the amount of plug work required.
I chose to use 700c size wheels throughout. This option was selected because with my 34 inch inseam, I can still fit the 700c front wheel between my legs and reach the pedals. Also, a study I did suggests that the improvement in rolling resistance of the 700c sized tires available (for which there is a huge selection of very high quality options) will surpass the added aerodynamic drag of the larger wheel fairings. The larger wheel fairings also contribute to improved high speed stability, as described later.

Like several modern speedbikes, I have chosen a fully reclined rider position to minimize the frontal area presented to the wind. In this position, I should still be able to produce good power output.
With a trike there are several sources of drag not present in a bike. But I believe there are also some drags present in bikes which are minimized in a three wheeler. So to be competitive with the bikes, this design must do what it can to capitalize on its strengths, while minimizing its excess drags.
Many trike designs choose to place their wheels inside the same fairing as the rider. This practice makes for some very large and consequently draggy (by speed bike standards) vehicles. 
The Orion design places the wheels outside of the main fairing in smaller individual wheel fairings. This approach does several things. First, it greatly reduces the frontal area of the total vehicle. It can also reduce the surface area, depending upon the details of the design. Secondly, these individual fairings act as their own wheel enclosures, reducing the wheel pumping drag that becomes significant with speeds above about 50 mph. Third, the wheel fairings act as vertical stabilizers like on a twin tailed aircraft, enhancing high speed stability, especially in gusting crosswinds. Forth, having the wheel fairings out on the tips of the wing may actually reduce their drag compared to a single inline rear wheel in a bike. The reasoning here is that both the front wheel and the main fairing are sources of turbulence. This turbulence may greatly increase the skin friction on the rear wheel of a two wheeler, but with the Orion design, the two rear wheels should see “clean” air, allowing them to maintain a high degree of laminar flow. We’ll have to wait until I can perform some tuft testing to verify this theory.
Bikes are subject to a control power loss. That is, a certain amount of power is lost just keeping the vehicle upright. Theoretically a trike would not have this loss, but in practice I have found that it can still be an issue. So the challenge here is to make the trike supremely stable so that all power can go into propulsion, sparing almost none for control.

So, all of this theory is interesting, but is it real or just bull? Well, there is only one way to find out!

Progress: 

Picture by Mike Mowett
Sept 29, 2004:
As I mentioned above, I was able to take the trike chassis to Battle Mountain this September, and even entered it in the quarter mile drag competition. My goals for doing so were to test how well I could put a lot of power into the pedals, and to see how it handled in a “high speed” situation. I had only finished getting to trike ready the morning of the race and did not put on gearing for fast accelerations. Consequently, I did not win a single drag race. However, since winning a drag was not a goal, that was not a problem. I felt that the trike took all the torque 
I could stomp into it very well, and it showed it’s high speed by gaining on each of my competitors at the end of the three races I entered. Since two of these races were against Mark Mueller in his fully streamlined Boxster, I was very happy with the results. If I had only had the right gearing……….. Estimated top speed in the drags was 33-35 mph based upon Mark’s cyclometer max speed.
Since Battle Mountain, I have attached a tail light, a rear view mirror, and a cyclometer, all to make the vehicle more trainable and roadworthy. I am also fabricating a new narrower wing to reduce the track from 36 inches down to 26 inches. 

In a recent test out on the country roads outside of Chico (see picture above in the ‘Concept’ section), the tail light and rearview mirror worked better than expected, offering a clear view of overtaking traffic, which obviously saw me from a long ways off, as they would change lanes hundreds of yards behind me. The cyclometer must have been broken though as it registered faster than expected cruising speeds, but slower than expected top speeds. Darn thing must not be working right.


New Narrow wing 

Original chassis for rear wheel steer
If I had known then what I know now… When I started this version of the project I wanted to have the Orion be rear wheel steered. But as I got into the nuts and bolts of how that would happen, I decided that was too much work for a first generation vehicle. So in mid fabrication, I changed to front wheel drive with a traditional fork. I had some concerns about the design because of the 700c front wheel, but the machine seems to work fairly well. At this stage, I am using 6063-T6 1/8 wall box tubing because it is available (i.e. I have a bunch left over from a previous project), and easy to work.
Cut and weld. Chassis jigged to accept a front steering fork
Just add heat and a little filler rod, and it looks like this.

I have a full sized lathe, and a small hobbyist sized milling machine that I have retrofitted with CNC. These two machines are invaluable in making all of the various frame parts and fittings.


The bottom bracket shell in 7075-T6 aluminum. Made almost entirely on the lathe using the 4-jaw chuck.
Below is the Midshaft assembly. Cassette body is Shimano 7/8 speed with pawls removed. Attach fitting is turned in 7075-T6.
Rear derailleur hanger CNC machined on the mill in 6061-T6 aluminum. Borrowed from an upright frame project also in progress.
Below are the rear wheel mounts, which were squared and turned entirely on the lathe using 4-jaw chuck in 7075-T6. The raw material is ‘scrap’ from my old job.
The Wing is held on by this quick and dirty 4-bolt clamp. Seems to work so far.
Steering column in 6061-T6. Kind of clunky, but designed for adjustability at this point. Later will make a simpler design when I decide where to put my hands.
Front derailleur pin to hold clamp-on style derailleurs. Will mount one when I figure out the cable routing (unanticipated geometry issue #237).
Current configuration of drive train. Single speed 16 tooth freewheel on old 126 mm rear hub, with spacers removed to bring it down to about 102 mm. The Cro-moly fork can just spread to accept this width. Currently can use 4 speeds on the mid shaft, as the cage hits the single speed chain if I try to use the fifth. Hope to move to 10 speed componetry to allow more gears. I see that Campagnolo just came out with 10 speed flat bar style ergo shifter/brake levers! Drool!

Next step - Fairing Construction


 


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