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

[visionary]

Update 003

So here is a concept sketch for the project. On the basis that a picture is worth a thousand words, it should make it easier for anyone to understand what I am aiming for.



The “sketch” is done in photoshop with actual photos of each of the major components (inc driver) laid over a CAD drawing to ensure scale remains accurate. I have left the body transparent so the internals can be viewed. I will post a plan view and front & rear views when I complete them. The size and approximate mechanical layout are all fixed at this point, but styling issues can be changed in the final bodywork. I would like to hear any comments about the body shape and its probable Cd, I am aiming for less than 0.2.
Since this project as all about aerodynamic performance to achieve the goals, any suggestions would be welcome.

[visionary]

Update 004
Although progress over past couple of weeks has been slow, I have made some decent steps forward. Firstly I won an e-bay auction for a Honda CBR600 frame, which I decided would make the perfect front –end for the project. The twin disc and decent telescopic forks will make a substantial improvement over the C90 drum and leading link set-up. Here are the parts cut ready for fabrication.




Secondly, I have arrived at a reasonable solution for the rear spring/damper unit which I am mounting in the lower body section. Initially it seemed to conflict with the location of the intermediate shaft, but I have been able to fit both items.




The intermediate shaft is needed to align the engine gearbox sprocket with the chain to the rear wheel. When centralised, the engine is too “slim” for the 160 rear tyre, and the chain dimensions would require custom sprockets making. I have solved this problem by driving the intermediate shaft (loose awaiting final machined spacers before welding) with a standard C90 chain and two engine sprockets. The original Z750 front sprocket is then fitted to the intermediate shaft and drives the stock chain and rear sprocket.
This allows more opportunity for gear ratio alteration to match the std 3speed box and target top speed. It also allows the opportunity of fitting an additional drive source (eg: electric motor) to further improve efficiency – but that’s more than I want to take on at present

[Frank Lee]

It looks nice. Quite the change, from C90 to CBR600- must be one hella change in the performance parameters? Seems that front end would be overkill (heavier, mismatched wheels) if the rest of the machine is still all based on C90 bits?

[visionary]

Hi Frank - yeah you are right about the mismatch. I know the front end (CBR600) and rear swing arm assy (Z750) are more than whats needed but I still want decent brakes on this thing! I'm hoping for about 130kg which is 45 more than the stock C90. if it does hit 100mph I want to feel safe - the C90 brakes and suspension are so inadequate (even for 50mph) that I have no choice but to upgrade
I could have spend weeks trying to find lighter parts but these came up cheap!

[Patrick]

Originally Posted by visionary

Update 003

So here is a concept sketch for the project. On the basis that a picture is worth a thousand words, it should make it easier for anyone to understand what I am aiming for.



The “sketch” is done in photoshop with actual photos of each of the major components (inc driver) laid over a CAD drawing to ensure scale remains accurate. I have left the body transparent so the internals can be viewed. I will post a plan view and front & rear views when I complete them. The size and approximate mechanical layout are all fixed at this point, but styling issues can be changed in the final bodywork. I would like to hear any comments about the body shape and its probable Cd, I am aiming for less than 0.2.
Since this project as all about aerodynamic performance to achieve the goals, any suggestions would be welcome.

Are you going to use outriggers like the E-tracer for when you're stopped?

[JasonG]

Might I suggest fully enclosing the rear swing arm and tire ?

[visionary]

Replies
Patrick - for my main prototype (dont forget this is just a spin-off project) I found a more elegant solution to the outrigger problem but it is not perfected yet. For this vehicle I will start with a simple movable body section through which I can extend my leg(s) when needed
JasonG - I'm agonising over that point. I know I really should but I also like the look of an open wheel. Reading other threads there seems to be a big question about sidewind stability, which I'm sure will be worse with a fully integrated body enclosure of the rear wheel. I could make a section that moves with the swing arm (like a "super hugger") and try that but it will be one of the final jobs on the list. But I do intend making the exhaust muffler as a deflector to clean-up airflow to the rear tyre (theres a new kawasaki does something similar) and energise the wake with exhaust gasses.
Thanks for your interest guys - I would love to hear more opinion
Pete

[Quasimoto]

Originally Posted by visionary

So here is my first project update. Images are of the Honda C90 motor, which I am using and the rear wheel/tyre & swing arm.
Motor first. I bought a blown motor (seized big-end) to use as a dummy for fabrication purposes. I’ll swap it for my good unit when I strip the bike apart, but I don’t want too much stuff apart at once. I’m using the electric start version as kick starting will be impossible with the motor mounted below the seat and fully enclosed by chassis and bodywork. The starter adds a bit of height to the assembly but without a purpose built unit I don’t think I can do any better. The carb needs to be remounted – eventually I will go to fuel injection but in the short term I will cut-and-shut the inlet manifold to create a lower profile. This part will sit just below the bend in my knees, so it can be a bit higher than the seat base.
The rear wheel assembly is from a Kawasaki ZR750, no idea what year, I just bought it from a motorcycle breakers because I liked the fat 160 rear tyre. Despite the difficult aims of this project I continue to make compromises because this thing has to look “cool”. I know mass and drag penalties will come with this set-up but running around on skinny tyres could kill the attractiveness of the finished article.

Craig Vetter has a point about the best vehicle being your first choice, and for me there is great appeal in a “good-looking” machine. In the few weeks that I have had the C90, my eyes have been reopened about the practicality of motorcycles. Although I have always considered myself a “biker” the truth is that I have not used a bike as regular transport since my teens. They make great toys but no way would I choose one over my car for anything but a “fun” journey.

With all the unsprung weight you're adding I believe you'll have a hard time meeting your goals.

[Patrick]

Originally Posted by Quasimoto

With all the unsprung weight you're adding I believe you'll have a hard time meeting your goals.

Unsprung weight? It looks to me like the additional weight is all sprung.

Visionary - I suggest you move the engine over and back and eliminate the jackshaft. That will reduce weight and driveline losses. Also, you could go with a pull-start system like the California Commuter used. They adapted a lawnmower pull starter to turn the kick starter. That should save you some weight in the electrical system (smaller battery, no starter motor, no solenoid).

[Quasimoto]

Originally Posted by Patrick

Unsprung weight? It looks to me like the additional weight is all sprung.

Actually, you know not of what you speak. Unsprung weight is all of the motorcycle that is not supported by the suspension, such as the wheels, brakes, tires, etc. Check it out.