Project 100 (custom enclosed Honda C90 targets 100 mph vmax and 100 km/L FE)

[PeterS]

Cover that front wheel!

[Quasiff]

Steering damper won't stop a tank slapper. In some cases it may make it worse. See Tony Foale's web site www dot tonyfoale dot com for sources of info, especially his book. Another very useful source is John Bradley's "The Racing Motorcycle- a technical guide for constructors". Hard copy only, order direct from his web site. I know we're not talking about racing bikes here, but there's lots in common.

Tele forks, or whatever you have, will be simpler for a prototype, and I expect the frame build will be done again or much modified anyway after the prototype is running. Building an alternative front end is a significant project in itself and has virtually no effect on fuel efficiency. There are so many new (to Visionary) ideas being applied he will discover lots of things he will want to change. There are always compromises in engineering and this is no exception. I find that (cosmetically good) bodywork is NOT easily modified. Frames are much easier in my experience.

I think the biggest challenge is to keep the bike light enough that the little engine will cope.

Pneumatic actuators are fast and reliable, but not energy efficient. I've designed and built many machines that used them for all sorts of applications. What is wrong with the machine tilting onto a side stand when the rider gets out? The Quasar used a double sided, internally hand operated side stand and it works fine. I've ridden one, so I'm not just speculating.

[Curtis in Texas]

About your kickstand. I've spent considerable time hashing though how I'm going to approach this probelm when I get started putting mine together. Let me see if I can explain this without confusing eveyone! Sorry, I tend to get a bit wordy!

Have you considered an under the dash foot operated parking brake lever to activate a pair of outrigger side stands by cables? With one kickstand outrigger on each side you wouldn't have to worry about being able to get your leg outside the body work as much. Those doors are going to be tricky, especially with the hatch type entry door. Those parking brake levers ratchet on the downward stroke and are released by raising the latching cogs with either a solenoid or manual release levers.

With some small limited swivel style jockey wheels on the kickstands tips you could apply as much pressure as needed to keep the bike upright. The wheels will give you enough rollout from a stop to aquire your balance from a dead stop befire stowing. Add some solenoid to release the brake lever rachet and you can stow them quickly with nothing more than simple springs and a push on a button or yanl on a small lever.

I've thrown this idea out before, but I can't find where I've mentioned it here in thei thread. I went back 8 pages!

My design for my bike will have two pedals side by side so I can innitiate both together. (I've got big feet!) Then if I find myself on a lean it will just be a simple matter of pushing the low side to get back to center. Then with individual release buttons when at a stop light I can use my foot to hold pressure on the high side pedal and let some down pressure off the high side gradually. Maybe add some manual release levers to allow fine tuning the down pressure without tripping the solinoids.

I would think that if the E brake pedals were on the left side mounted above a foot shifter and you used a hand clutch they wouldn't add too much activity to the left foot. A push button mounted on the steering stem would make stowing the parking stands a simple matter once underway.

But, then again if you added a Vespa/ Lambretta style clutch /left hand grip rotation shifter, your left foot could concentrate on balancing on the outriggers when stopped.

It makes perfect sense to me without adding all those potential leaking hose fittings and slow reaction times with pneumatics. Parking brake cables and housings are plentiful in salvage yards and almost free. Not much demand for them.

Just thought I'd throw that out for consideration.
I hope it makes sense!!!!!

Curtis

[ElectricRider66]

I didn't say they would prevent tank slappers, I said they should "reduce the frequency of this happening".

Please include a quote from your sources explaining how a steering dampner can actually make it worse. I'd need to know about this.

Here is my theory/opinion on steering dampners. Every system has a set of natural frequency's where the system achieves resonance. The purpose of the steering dampner is to have a resonance that is different than the steering system so that they provide checks and balances to each other.

Can a system go into harmonics with a dampner in place. Sure. But, if the dampner is selected and applied properly I'm assuming it will reduce the frequency of circumstances underwhich "tank slapping" will occur.

In my experience, I've been able to take two bikes that were prone to tank slapping and make it them less prone to tank slapping via a steering dampner.

[Quasiff]

Originally Posted by ElectricRider66

I didn't say they would prevent tank slappers, I said they should "reduce the frequency of this happening".

Please include a quote from your sources explaining how a steering dampner can actually make it worse. I'd need to know about this.

Don't take my word for it. Have a read of Tony Foale's "Motorcycle Handling and Chassis Design" for an expert explanation. I posted where you get the book from. It's a cheap investment compared to building anything to get an understanding of what happens.

In case people are wondering, tank slappers are not the same as the hands-off slowing down wobbles which a damper (or resting a hand on the bars) can cure.

[BenjaminT]

Originally Posted by visionary

Some replies
Benjamin T ...My opinion is that telescopic forks, while far from perfect, function adequately. Just take a look at MotoGP bikes, with incredible loads and massive grip from slick tyres, ridden to absolute precision using this lightweight and simple technology – what’s not to like? My requirements for handling precision are likely to be far lower, and hence below the critical limit for performance.

From a design viewpoint, a commuter vehicle requires the same level of consideration as a racer. (If Moto GP et al allowed Hossack, they'd all be running them within a season. Being able to brake harder/later than the rest puts you in front.) Just because something isn't going to run on the track doesn't mean you can slack off on the design. You hope this will take-off with the general public, right? That means you're hauling wives, brothers, daughters, fathers, and so on. Safety is a critical point of performance.

Tank slappers are not limited to high rake-angled racers. Here's a nice cruiser getting laid down.

ouch

Heck, I've managed to do it on a suspension bicycle, once. While braking, that front fork shooting forward and bucking the bike during a loss of traction is killer.

Additionally, as is true of any prototype, I don’t fully understand my handling requirements yet. Until I do, I want to use a “known constant” or control, which will allow me the chance to evaluate the vehicle handling – hence use something familiar. If, a year from now, I’m struggling with a handling anomaly, please feel free to remind me.
I am very grateful to you for “the rule of ten” and other manufacturing theories that I found at your suggestion.

Okay, I actually re-reviewed the entire thread and gave a closer look to the pictures and drawings. I don't mean to make this sound testy, but. It's just the way it's being delivered:

Ask yourself, where exactly are you in the design stage? Because it looks like you never built a model to study the structure and suspension geometry. You really, really, really, need to stop and re-evaluate. I don't have a clear picture of where your build is at this exact moment but, I can tell you right now your steering is unbalanced.



The handlebar axis is not parallel with the steering head axis. (I can't tell from the pics if the connecting rod forms a parallelogram. The joints should be positioned at the same relative angle and distance from their axes.)

I'm going to leave the criticism there for now...

(One last plug for the Hossack and sharing a design theory of my own.)

The KISS principle doesn't really give one a scale to go by. So I say a design is simple when guys banging rocks together in a cave can make it. While we have access to the latest and greatest in precision fabrication equipment and techniques, it's also expensive. A Hossack can be made by a home hobbyist with shoddy equipment. Tele-forks require precision machining, hardening, and plating and a lot more QC. So when it comes to production, there's a significant price-point difference when the other design can be made from two stampings, four bushings, and two spherical joints.

The final consideration I'm going to lay on you is "tuning." You can do all the development work you want, but, as you said. You won't know how it's going to perform until you build it. With threaded Heim joints positioned between shims, you can adjust the angles and dimensions until you find the sweet spot for production. No such luck with telies.

Take care, and at the very least fix the steering before you take it on the road.

[Quasiff]

Originally Posted by BenjaminT

From a design viewpoint, a commuter vehicle requires the same level of consideration as a racer. (If Moto GP et al allowed Hossack, they'd all be running them within a season. Being able to brake harder/later than the rest puts you in front.) .

There's nothing in the MotoGP rules that prevents any front suspension so far envisioned. I suspect it's conservatism and some unfamiliar feedback issues with some designs that prevents it.

Originally Posted by BenjaminT

Tank slappers are not limited to high rake-angled racers.

Tank slappers are not a characteristic only of tele forks. They could occur with any front end with positive rake and trail combination, given the right conditions.

Originally Posted by BenjaminT

The handlebar axis is not parallel with the steering head axis. (I can't tell from the pics if the connecting rod forms a parallelogram. The joints should be positioned at the same relative angle and distance from their axes.)

It looks to me like Visionary has a single drag link, so unless he runs out of angularity his steering will work OK. A bit different at extremes, but not noticeable withing the 2 or 3 degrees used in normal steering. Having said that, the bent link looks like it could have a problem with stiffness, and I too would prefer to see the handlebar and steering axes closer to parallel. Anyway, it can easily be checked statically.

Originally Posted by BenjaminT

A Hossack can be made by a home hobbyist with shoddy equipment.

The final consideration I'm going to lay on you is "tuning." You can do all the development work you want, but, as you said. You won't know how it's going to perform until you build it. With threaded Heim joints positioned between shims, you can adjust the angles and dimensions until you find the sweet spot for production. No such luck with telies.

A poor Hossack can be made simply. A Hossack that performs better than a modern tele fork is a project on its own. What is chosen depends on what the aim of the project is. This is a Honda 90 powered bike, which is hardly going to stress any tele fork, let alone the one he's selected. One advantage of the Hossack over the tele in this case is that it can be lighter. However, a simpler way to save mass is to make a leading link fork that uses the steering head and geometry of the tele fork. Or pick a lighter front fork and wheel.

No argument that the Hossack looks to be a better concept long term though.

[big shafe]

Originally Posted by visionary

Some replies

Big shafe – just to clarify, I have two things to consider. Firstly, temporary support when stationary during a journey (stop lights) and secondly, permanent support when entering/exiting the vehicle (parking). Each solution must be independent of the other.
Stop lights. In the short term I will use access panels in the lower side area to allow the driver to place his/her feet on the roadway, just like a regular motorcycle. These panels will move independently of the top canopy, and will require a degree of automation. I like pneumatics for this task, but have not finalised a design yet.
Parking. The parking stand will comprise a pair of “legs” which need a fairly wide base, and so will deploy at about 45degrees (viewed from front). They must lock into an “overcenter” position to remain deployed for long periods, and must allow for suspension travel when the driver gets out. Therefore a degree of lifting is essential, which will require power assistance. I like pneumatics for this role too, specially as some synergy with the stop-light solution is possible. Here is an image of how I think it will all work

Why do they have to be separate solutions? Surely you could adapt one mechanism to serve both purposes.

If you hit city traffic, opening and closing the doors will become monotonous very quickly.

[visionary]

Update 012 Let testing commence!
All preliminary building work is now complete. The “dummy” engine has been swapped for the original C90 engine, the inlet port extended and braced, exhaust primary stage completed, temporary (test) fuel tank fitted, and wiring loom extended to fit. The images below show most of these solutions, some temporary others are permanent.







The motor runs OK in its new location, despite severe vibration. The engine is exactly as I removed it from the C90 frame, where it was bolted firmly in place. During its original use I was never aware of a particular vibration problem, but then footpegs, bar grips and seat kept me isolated from the full effects, but mounted in my frame this seems a BIG problem. Everything rattles and shakes, and tools keep falling off the workbench with alarming regularity, so I’m quite surprised by the effect. I’m not sure why these vibration effects should be so different, perhaps it’s the “box” nature of the frame design.

The gearchange solution I’m using at the moment is a simple hand operated lever reaching down to a cut-down footchange lever. This rests alongside my left thigh and has a light simple operation. Eventually it will be replaced by a handlebar level system, but I can use it like this while I work on more urgent issues.

The first tests will be a short run around the industrial estate before going to a local disused airfield. At this stage all I’m checking is the driveline, brakes and steering are operative prior to going on the road. I will report on how it performs but I expect a further month of work making it road legal (fitting lights, indicators, etc).

[bschloop]

99% of all automobile engines sit on rubber bushing style isolation mounts, you can really feel it when one goes bad the whole car shakes. you may want to do the same with your bike as the frame and seating do not isolate you from the vibration of the engine. otherwise maybe a seat suspension like on a tractor or semi would give you a smoother ride.