[KrisWood]

Hi everyone! Now that my research thread has served its purpose, I'm ready to actually begin work on the project, so here I am with a fresh start.

Having no experience or equipment for welding, I'm wary of building a Frankenstein trike out of chopped up bikes bolted together.

A more sensible idea to me (and reinforced by my research) is to build it from a material I DO have the materials and skills to work with. This blog showed me that a wooden tadpole is indeed doable. He says he's already put 7000km on it and no major problems.

http://blog.borisbeaulant.com/

Plans for his "Zelo" can also be found on his site:
http://blog.borisbeaulant.com/wp-con...n-tricycle.pdf


While his design is beautiful and functional, he mentions in a few places that the steering is not very good, and that the design is not terribly efficient. It's mostly attractive and durable.

The design I've decided on for my trike is the Thunderbolt by Practical Innovations:

http://www.ihpva.org/Projects/Practi...ons/index.html

and incorporating some elements of the Thunderbolt MKIII / Spitfire later developed by the same person:

http://www.hellbentcycles.com/

My end goal is to use the design precision of the Thunderbolt trikes, and some of the methods of assembly seen in the Zelo. In this way I should end up with a vehicle that is structurally sound, efficient, and aesthetically pleasing.

I will of course need to work the electric motor, batteries, and supporting hardware into the design, but I'm fairly certain the motor will fit under the seat, and the batteries can be built into a framework on either side of the rear wheel. If I need additional battery space I could foreseeably put some below the crank in the front as well to further balance weight distribution.

Because I'm building out of wood I decided the methods used in the Thunderbolt construction via welding tubes together would be impractical to emulate. Instead I've decided to use methods of joining wood together used in boat building, which will give it a bit of a nautical visual theme.

Thus the name: The stormy element of the Thunderbolt name, combined with the nautical visual theme, evoked images of Shakespeare's "The Tempest", and I instantly knew the name would be perfect for it.

And now for some images! The following are my concept sketches that may or may not reflect the actual placement of components. The crank will likely move farther aft, since it was designed for a 36" inseam and I'm a 34". Doing so will also reduce the amount of material going into this and make it lighter.

Aside from the sketches we have some photos of my work space and available materials. The boards I've got laid out on the floor are a sketch model of approximately what the body will look like when assembled. The pieces are not cut to scale and were simply pulled from the pile based on their approximate sizes. Also while doing this I realized the 2"x2" main bar (I keep wanting to call it the keel) is going to be far too slender for the amount of weight that'll be going on here. It'll need to be a 2x4 instead, or maybe two 2"x4"s bolted together around the horizontal frames, the way the keelson is attached to the keel on a boat. Hmmm I like that idea.

Without further ado, the pictures from Day 1!

[Amberwolf]

I like the idea so far; I've little relative experience with woodworking, so I'll have to leave possible help with that for you to people like Woodsmith. You might see if he's interested in this project by PMing him with a link to the thread.



In case anyone new to your project would like to see the research thread without digging for it:
http://www.diyelectriccar.com/forums...xii-44876.html

[Darxus]

Neat.

One of the things that frustrates me about the way these forums get laid out is how long it can take to figure out the current state of a project.

"120VDC Permanent Magnet motor. 2.25HP 6200RPM and 18 amps."
"The first prototype has a target goal of 5mph (unassisted by pedaling) with a pedal assisted maximum range of 5 miles."
Single 12v car battery.

And it looks like you're planning to dangle a couple very small children in panniers over the rear wheel?

"36v with a 20amp motor, which gives a maximum power at the motor of 720w. If I were to use a similar setup, assuming that my motor's max amps is 18a as shown on the label, that would give me 648w at full power. If I go with 48v that'd give me 864w."

Yup, you can take it up to 120v, since that's what it was made for. Of course, that's if you run it the way it was designed, as previously mentioned. Running for the amount of time somebody would use a treadmill, and with active cooling (fan / air ducting).

120v * 18 amps = 2,160 watts.
2,160 watts = 2.90 horsepower - not some approximation, they're equivalent units of power. Before loss due to inefficient conversion from electricity to force, and friction (gears, chains, tires). Based on that 2.25hp figure, that motor itself is 77.7% efficient (peak?). Your 864 watts = 0.87hp, and with the 77.7% motor efficiency, is 0.68hp (plus loss from gearing and tires).

You can get batteries that are cheaper than car batteries, with higher voltage (and lower amps). Tiny 12v lead acid motorcycle batteries might be useful. I'm curious how much you can get away with, say, doubling your amps and halving your volts to achieve the same watts, without melting or snapping something.

If you are going to put kids in seats at the rear wheel, I encourage you to calculate your center of gravity. People seem to often be of the opinion that with a reverse trike, the CG should be one third of the way from the front wheels to the rear wheel, to equally distribute the weight among all the wheels. I mostly bring this up out of concern for your tip over angle. If your CG is at the rear wheel, tip over angle is 0, and you fall over. If your CG is at your front wheels, your tip over angle is based on the width of your front wheels (angle between vertical CG and contact patch of a front wheel).

[KrisWood]

Thanks for the reply and all the great info! I guess putting the batteries up front is a good idea after-all? Prototype 1 won't have any back seats of course, that'll be saved for the second prototype which should be a bit better designed. I suppose I could test it out with panniers full of sand or something? hmmm...

The state of Oregon allows 1000w motors in electric assisted HPVs, so if we keep amps at 18, that means the max voltage I can legally put through this is 55.556v for 1.34hp, or with 77% efficiency is 1.03hp. If we calculate the 77% efficiency into the equation, 72v (6 x 12v) for 997.92 for 1.338hp. My question is, how does this horsepower effect the performance of the vehicle on the road? And would it be worth carrying around 6 batteries?

I am only using the single 12v car battery for the second prototype during initial testing. It will be replaced by more, smaller, and more efficient batteries. When I first started planning this project I had zero funds for the project. That has changed. I'm wondering if the battery pack would be better placed under and slightly forward of the driver's seat. They'll easily be heavier than anything I will put in the back.

I'd rather not increase amps to save on voltage because that would give me a lot of power for a very short time, since battery charge is measured in amp hours, right?

Also something I've been wondering the last few days is, is amp usage independent of the batteries? Meaning, if the controller is sending 18a to the motor would it be drawing 18a from each battery, or would it divide it up into an equal amount per battery, so that 6 @ 12v would get 3a each? If the former is the case adding more batteries will be considerably more detrimental to performance since I would not be gaining ANY running time off the extra batteries and would be better off using fewer, higher quality batteries.

[Darxus]

I really don't know what ~1hp would be like on your vehicle. I look forward to hearing

I think you've got the electrical stuff pretty confused, which is easy to understand.

Power = watts.

Volts x amps = watts.

More volts, or more amps = more power = go farther and / or faster.

The amount of power in a battery is measured in watt hours. Which is heavily affected by how fast you drain the battery (the faster you drain the battery, the less power (watt hours) you get out of it).

Adding batteries will add run time. I'm pretty sure it's as simple as controller output of 18 amps = input of 3 amps per each of 6 batteries (plus, of course, loss from imperfect efficiency of the controller).

I still don't get the difference between volts and amps. Fortunately, I seem to have pretty much nailed down what I'll use for my project without that understanding.

[Woodsmith]

Interesting idea!

I would be tempted to construct from a hard wood rather then a softwood for the final testable version, lots stronger and less bulky giving more space for you and the batteries.

I don't know what facilities you have but I would prefer to see the main backbone made of bent laminations to form the shape and then the front axle, also in laminations, interleaved for strength.

You will need to ensure the front axle is rigid enough to stop it being knocked out of square with the backbone and to not allow the backbone to twist out of the axle.

Make sure you bond some tight fitting metal sleeves into any holes you add to the wood for the BB and steering kingpins and other structural bolts and fixings.

I would avoid mounting bodies on each side of the rear wheel. Luggage you can balance but unless the bodies are inert or severly restrained they will move and tip you over.

Have you thought of making a tow along two seat, two wheel trailer?
You could put a motor and batteries in the trailer too, if the laws allow, and then have a throttle pot on the drawbar so that it only drives if you pull on it and stops if you push on it. A controller with plug braking would be good for this. That way you can cycle or drive off and your trike won't notice the trailered load so much and the trailer can never push the trike along or over.