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Side-wind resistant streamliner.

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Balor View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Balor Quote  Post ReplyReply Direct Link To This Post Posted: 03 July 2020 at 6:56pm
Ok... I think I've solved the wind steer problem given positive trail for good.

https://imgur.com/a/ytuaU50

If you flip the VPS steering (like that on Horn's bike) upside down, instead of getting virtual positive offset in turns (due to virtual steering axis inclination), you get virtual negative offset, a ton of return to center force yet close to zero 'trail' in conventional sense - as seen from the side, hence SIDE force has no leverage to steer you, and when you brake in a turn the wheel will try to self-right instead of going to full lock.

The problem is, you need a ball joint with rigid connection to the frame somewhere *inside* the wheel... or above it and you still get what amounts to a head tube and the effect of lateral steering axis tilt gets greatly aimplified.

I thinik it will work just wonderfully with a bogie forks with wheels spaced wide enough apart, and you can have suspension in a similar fashion like on Horn's bike too (but, again, flipped upside down).
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Balor View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Balor Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2020 at 10:08pm
OK, here is my take on it so far:


Zero trail geometry and a steering damper for stability... maybe I should add a wee bit more trail after all, but I'll need to do actual experiments with a fairing... which is getting severely delayed due to Covid-related (and work-related) stuff :(

It's is quite fine at speed up to about 50 kmh, but could not make it go faster yet w/o a fairing, but I think I want more stabilty after all (not to mention it is quite flimsy due to 3d printed connectors).

Maybe I should go with the way of Matt Weaver and DIY myself an electronically controlled steering damper - should not actually be hard, just need to find a way to actuate the damping setting on existing damper with, say, a simple servo...

Other than that, side wheels with steering damping should take care of strong unwanted toppling moments.
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RoyMacdonald View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RoyMacdonald Quote  Post ReplyReply Direct Link To This Post Posted: 06 October 2020 at 6:50am
I'm impressed that you can get it to 50kph unfaired.Clap 

All the best.
Roy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AlanGoodman Quote  Post ReplyReply Direct Link To This Post Posted: 06 October 2020 at 7:26am
Interesting choice of front tyre...

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Balor View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Balor Quote  Post ReplyReply Direct Link To This Post Posted: 06 October 2020 at 8:29am
Techically, nothing prevent me from hitting a steep hill, but here are not much of those around... so yea, that was on the flat, but accidentally with a different front wheel :)

I've also experimented with installing low-power e-assist, it's a great help for starting and uphill boost.
Ultimately, I want to install no less than two motors - a geared crank drive and dedicated regen brake, but I need to have it 'clutched' and this is not that easy.

Offroad setup is, well, because I'm using it for offroad for now. Great fun actually :)
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