Autotricycle Design

SimpleSimon

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Apr 18, 2008
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1,181
WOAH! I can't wait to see this thing!
Since you said that, LF, I figured I'd show you where I am with design work on the dual rear-wheeled autotricycle design I started yesterday. Louisiana does not consider a three-wheeled conveyance a bicycle, and the motorized bike laws are quite specifically addressing "bicycles" (two wheels only). So far as I have been able to discover, three-wheeled bicycles (delta or tadpole) are a total non-entity under LA laws, which leaves motorizing one in limbo as well.

The law does define an autotrike, and since I want a road worthy vehicle that meets my needs, I figure I'll just design and fabricate the d****d thing myself. As shown, it's just the bare ladder frame and the the rear subframe. Note that as designed, the rear subframe remains normal to the road surface whilst the front suspension and the ladder frame is leanable, to 35 degrees off vertical either way. In addition, the rear subframe is so mounted as to be able to flex vertically through approximately 3.5 inches (shock absorber controlled). I'll likely add more pics to this thread as the design process develops.

Right now I'm contemplating a common axle with 3 hubs mounted for the rear - two 26 inch outer hubs and a 16 inch middle hub and rim moddified to run an industrial link belt from the jackshaft immediately behind the engine. I've found a new Robin America 5.5 hp 4 cycle engine for $199 ($0 shipping!), and will modify the engine mount between the pivot and the fender/shroud frame of the rear subframe as needed for that.
 

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imperfectionst

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I've seen a recumbent like that. What's the advantage besides not having to balance?
 

SimpleSimon

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I've seen a recumbent like that. What's the advantage besides not having to balance?
Fair question. The "not having to balance" part is. for me, the biggest concern.

All trikes involve trade-offs. Trafitional delta trikes typically experience significant tire scrubbing, inside wheel lift, and other issues in turns at any speed at all, in large part due to the high center of gravity, and the mass distribution. Tadpole trikes with rigid frames experience similar issues when built with a conventional high COG.

By incorporating into the design significant caster angling (I'm going for 12.5 degrees), camber of approximately 1.5 degrees (adjustable), and careful implementation of Ackerman angle steering geometry, those problems are greatly reduced. The semi-recumbent seating lowers the COG greatly, the locked pivot parallelogram front steering with active self-leveling and the leaning ladder frame and self-leveling rear subframe go further toward insuring consistent power delivery and non-scrubbing rear wheels.

It's a process of trade-offs and compromises aimed at maximizing desirable characteristcs while minimizing undesirable ones.
 
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Alaskavan

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I'll be following this thread. I have a small Wankel that I'm thinking about putting on a full size fully suspended tadpole.
 

Eco Speeder

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May 11, 2008
Messages
158
SimpleSimon; Right now I'm contemplating a common axle with 3 hubs mounted for the rear - two 26 inch outer hubs and a 16 inch middle hub and rim moddified to run an industrial link belt from the jackshaft immediately behind the engine. I've found a new Robin America 5.5 hp 4 cycle engine for $199 ($0 shipping!) said:
Absolutely awesome my friend!! Keep up the good work. I am very enthused and impressed.

One humble suggestion; when you get to this aspect; try to keep deck part of the frame as high off the ground as possible. This thing has to be able to compete in traffic. Your design so far should make that easy to accommodate.
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Michael
 

Eco Speeder

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May 11, 2008
Messages
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I've seen a recumbent like that. What's the advantage besides not having to balance?



Wrong question perhaps; What's that advantage of 4 wheels over two?

To delve into that further...Whats the advantage of 4 wheels with suspension that lean??

Simon is working on a vehicle concept that is as potentially more revolutionary and as impacting than the automobile or airplane has been. Moreso perhaps. We need this now. The first autos were perceived as a rich persons nuisance toy for years.

Once the various attributes of this design type are dialed in it will easily handle freeway speeds. The handling will make sport motorcycles seems archaic, dicey and dangerous.

How does 95 miles per gallon and a driving experience that makes an expensive sports car seem like a dead lay register?:LOL:


Michael
 
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Alaskavan

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Simon, if it's not too much trouble, please post links to sites where you find important relevant information.
 
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JemmaUK

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I do hate to be a killjoy, but I do see one problem with this build and thats the engine...

5.5hp is liable to get the local cops bouncing around with joy especially if its that distinctive a machine...

You get a nice friendly one whos not in the middle of a divorce and they might just stop you to have a look at the machine... you get the other sort and they'll try and hit you with every law they can think of...

I do like the idea of a protected drivewheel but what happens if the chain/belt jumps and twists itself round the axle?

Is the machine going to be pedalable? because if it isnt in most places it would be seen as a moped/motorbike and taxed/controlled accordingly...

If you have something similar to SVA out where you are they will make it a royal pain to get that through just because of its unusual configuration...

I just worry that you will finish all that work to get it on the road and then find out that even leaving it outside on the driveway will have every cop in the neighbourhood trying to be the first to ticket you :(

Jemma xx
 
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Alaskavan

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Jemma, I had many of the same concerns when I built my trike. So far the police smile and wave. If they told me tomorrow that I couoldn't ride it anymore, I'd still be happy I built it.
 
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