Robert Wood's Leaning Delta Recumbent Trike

Robert Wood's Leaning Delta Trike project
Building a practical streamlined commuter vehicle

My motivation for this project started long ago. I built a Tadpole trike some years back, and I made a full fairing for it with coroplast. It had several problems that kept me from riding it. 

1)  Since the frame is fixed you can't lean it into a corner. This means you lose speed, eat tires off the front, and you have to have a very wide track to keep all the wheels on the ground in a turn. The wide track also means a very wide body if you want to keep the front wheels inside the body for good aerodynamics. 
2)   Tadpole trikes will wobble from side-to-side due to the momentum of the riders legs as they go through a pedal stroke. Some tadpole trikes do this more than others. The determining factor is the size of the rear wheel. The bigger the wheel the worse it gets. Now if you put a full fairing on a tadpole trike this situation gets much worse as speed increases. The only way I could work around it was to run a really high gear and turn a low cadence at speeds above 25 MPH.
3)  With the body fixed riding into cross wind was a workout in itself keeping the vehicle going in a straight line. It was almost uncontrollable in wind speeds above 15 MPH. 

Please, people with tadpole trikes. I am not knocking your vehicles. The tadpole trike is a great machine and there are a lot of people who ride and love them. I just wanted to share some of my experiences with this type of HPV,  yours may have been different.   

O.K. with all the drawbacks of the tadpole trike above the vehicle was disassembled and the remains are still hanging in my garage. I was into racing and my quest for speed led me to build my first lowracer during the winter of 97&98. I built a coroplast body for it and raced it very successfully for the next two years. I trained and rode this bike on a daily basis but it to had some draw backs. I couldn't ride it back and forth to work, I couldn't ride it in bad weather conditions and it couldn't be ridden at night (no place for lights).

Last fall I was surfing the web and came across a web site that featured tilting three wheelers. I was interested so I kept researching and found Paul Sims Leaning Delta Trike. I read the article and saw the pictures of him racing it and I knew I had found the answers to almost all the problems I had had building a reliable, fast, all weather commuter. I e-mailed Paul and he was kind enough to send me the dimensions of his machine. With this and a couple of pictures on the web I built my machine. My trike has a much narrower track than Paul's machine. I did this to keep the body as narrow as possible. My head tube angle is not laid back as much as Paul's. 

1/13/01 - 

The starting point for this project was two 20" Boy Mountain bikes. I bought them at Toys "R" Us for $60.00 each. I cut the Head tube out of both of them, used the chains, derailleur, three sets of brakes, two front wheels, one back wheel, three brake handles, shifter cable, brake cable and half of the rear swing arm assembly.   

Here is the wooden jig for building the trike frame. This is an essential for creating a straight frame.

Detail of the bottom bracket in the jig being braised in.
Front wheel with derailleur and brakes mounted
Rear suspension part laid out, ready for assembly
Front wheels from the donor mountain bikes, reshod with new Primo tires.
Here's the frame before the addition of the rear suspension
Here's the frame with the rear suspension in place
A closer shot of the rear suspension showing the suspension bushings in the center, as well as the lean control mechanism.
Fully suspended front wheel drive, with skate wheel idlers. 
Here are the major specifications of Rob's trike:
  • Head tube angle 70 degrees
  • Wheelbase  45" Track 18"  
  • Maximum lean angle 50 degrees
  • Weight  34 pounds (without fairing)  
  • Full suspension front and rear
I test rode this vehicle on 01-13-01 and it handled great and did not show any tendency to wobble as a tadpole trike does. It rides like a 2 wheeled machine. 

2/12/01 -  

The painted delta trike frame with all of the manufactured components. 

The next step of the project involves making the body. It will be constructed by gluing together pink Styrofoam and then hot wiring the basic shape. I will then sand all the compound curves of the outside body. After the sanding is complete I will epoxy a layer of fiberglass on the outside portion of the body. Then I will hollow out the inside and glass it. This will be a little heavier than a body constructed with the vacuum forming process but it will be much faster to build because I will be skipping the process of making the molds.  

The fairing templates are made out of Coroplast. The top and side view forms are made to hot wire the foam that will be the body.
The fairing top view template. Note that only 1/2 of the template needs to be made as the two halves are mirror images
The side view template
The completed top view plywood template, which will be used as a guide to hot wire the block of Styrofoam.

2-17-01 - 

The spring loaded pin (below), is what keeps the trike from falling over. The extra brake handle (Left) is what I used to disengage the pin. The piece coming off the Brake handle above is what holds the lower brake handle while the trike is in motion. When I stop, I take the lower brake handle out of the holder and the pin re-engages the rear assembly, holding the trike in an upright position.


Detail of the spring loaded pin, which keeps the bike upright when it is stationary.
The completed delta leaning trike. 

I was talking to Garrie Hill on Friday and he asked me if the paint made the trike any different. I told him I thought it made it a good 5 MPH faster. He laughed and said "he needed some of my paint".

Now it's time to work on the fairing. The fairing mold will be constructed of Styrofoam slabs, which will be hot wired to shape and then sanded smooth. The Styrofoam mold will be covered in fiberglass, finished smooth, cut open and then the foam will be removed. 

The hot wire tool is made from 2x4, 3/16 all thread, 25' of lamp cord, a solid state ceiling fan controller and an AC transformer. 

The hot wire tool works pretty well, I cut the small pieces of foam in the picture in a matter of seconds.


Samples of foam cut with hot wire.

3-18-01 - 

This is a streamliner. Well not exactly yet, but this pile of 4 foot by 8 foot by 2 inch pink foam will soon be shaped into a streamlined body for the leaning trike. 

This fairing will be built using the "lost foam" method.

In order to make the streamliner just under 9.5 feet long, it was necessary to make some 18 inch extender pieces, and then interleave the 8 foot and 18 inch pieces together in the stack of foam.
Here is the stack of foam, glued together. You can see the extender pieces interleaved with the 8 foot sections. This seemed to take forever because I could only get a couple of pieces done every day
The stack of 32 inch wide foam, with the hot wire template on top. The hot wire will be drawn along the plywood templates (one on top, and one on the bottom) to carve the "top view" streamliner shape.
In this picture, 50 pound bags of kitty litter are strategically placed on the top template to keep everything in place while hot wiring the foam. I knew all those cats of ours would come in handy some day.
Here's the streamliner plug after carving with the hot wire. There are only a few places that  will have to be filled and sanded smooth.

The "lost foam" method of streamliner construction is when you carve the fairing shape out of a block of foam, cover it with a couple layers of fiberglass or carbon fiber, finish it, then cut it open and remove the foam. The advantage is that it's relatively fast, the disadvantage is that it make it harder to replicate the fairing.

In the early summer of 2001, after finishing the fairing and taking it for many test rides, Rob decided to put the project aside for a while.  He discovered that the faired trike was too much slower than his Coroplast streamliner to make it worthwhile at that point in time. The drag associated with the width of the fairing needed to fair the wheels, along with the added rolling resistance of the additional wheel, outweighed the benefits of being able to lock the bike upright. 

Rob says:
"I haven't abandoned this project. I have put it on hold for the next few months while I get my new streamliner together. I plan on pulling the delta back out of hibernation some time next year. I have some ideas I want to try before giving up on it. I am going to widen the track to 30" and put the rear wheels as far back as I can. This will do two things for me. 

1) The widened track will be more stable in the locked position.

2) With the wheels that far back I can use the same fairing that I am making for the projectile 2 project. Also with the wheels that far back the air flow won't delaminate from the body. If I fair the rear wheels it should help push the air flow back on the body because of the compression from the air flowing between the body and the wheel fairings."

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