Project Slipster: Streamlining the Kawasaki Ninja 250 (WIP Thread)
 

I tried to think if a good name for this project. All i could come up with is a cross between "slippery" and "sipster" (from Top Gear America's project).

I have mentioned previously in my Ninja 250 general thread about my ambitions to design and build a streamlined fairing for my motorcycle. I'm a 22yr old college graduate with a BS in PreMed Biology, and will soon be starting a new job with the degree that may require lots of driving. My motorcycle is my primary vehicle, so the main goal with this project is not only to improve the fuel efficiency of my motorcycle, but to also improve the comfort of the ride as well as extend the conditions for which i can ride (Temperature, weather, etc). The fairing will be made entirely out of steel or aluminum bar stock for the framing and a thin layer of fiberglass for the shell.

There are a few design considerations that i would like to follow:

1. The design will accommodate an upright riding style. This means i will be sitting comfortably with my back straight and arms relaxed.

2. The fairing will be at least as easy as the stock fairings to remove from the bike.

3. The fairing will at least consist of a front and rear fairing, and mounting and unmounting the bike will be easy. If possible, i would like to enclose the sides for better airflow from front to rear.

4. The front fairing will be as wide as my handlebars and foot pegs (approximately 30"), and as tall as my helmet in an upright position. The front fairing will extend forward past the front wheel and fully enclose it.

5. I'd like to retain the stock headlight, tail light, and blinkers with the fairing. The less parts i have to buy, the better.

6. The rear fairing will cover the passenger seat and extend up to the back up my helmet, possibly even having a back rest built in. The rear fairing will follow a tear dropped shape.

7. I'd like to incorporate storage spaces in the fairing, ideally front and low on the bike, but also behind me. I'd like to be able to carry a bunch of clothes, maybe some groceries, and a laptop.

Goals that I would like to meet:

1. Allow riding in sub freezing temperatures without having to wear 4 layers of clothes under my riding gear, a ski mask under my helmet, and ski gloves instead of riding gloves.

2. Be able to safely store payload on the motorcycle and not have to worry about it falling off the bike (a bungee coming loose)

3. New MPG goal : 125MPG

I plan on starting on the fairing soon. However, i would like to open this thread up for discussion and allow the EM community to provide suggestions and insight on this project. I have read the quests of Craig Vetter and others and understand a bit about full fairings on motorcycles.

Here are some designs i have whipped up real quick to get the discussion started.

First, a mock up with clay of a possible design:
http://i422.photobucket.com/albums/p...4425200531.jpg

Heres a quick side view of a fairing that fits an upright riding position:
http://i422.photobucket.com/albums/p...ryan/Body1.jpg

Heres a top down view of what the shape of the sides will probably look like:
First closed:
http://i422.photobucket.com/albums/p...dyTopView2.jpg
Second, opened
http://i422.photobucket.com/albums/p...pView2Open.jpg

Here is a current picture of my bike with extended windshield:
http://i422.photobucket.com/albums/p...3654972625.jpg

And here is an older picture with me sitting on the bike:
http://i422.photobucket.com/albums/p...3479417754.jpg

It could look something like the Prometheus EV Ninja:
http://www.blogsmithmedia.com/www.au...motorcycle.jpg

Craig Vetter Fuel Economy better mileage

Here some interesting reading for you...

Oh ya, Go Go Go!

Edit: Just saw that you've read Mr. Vetters stuff...

That clay model you made, almost perfectly resembles the "Rifle" body that Vetter sells.

My suggestion to aide in your 125MPG goal would be replacing your lights with LED versions. Of course, if you use the stock lights that hang out in the wind, it will completely ruin your aero... :P

I don't think a funtional backrest would do you any good, really. Seems like you're still slightly leaning forward in that pic, so unless the backrest was further forward than it needed to be, you'd never contact it anyway. Your back is slightly arched toward the thoracic vertebra, so the lumbar area could benefit, slightly.

Excellent! This will be interesting.

Suggestions... Well, there's likely nothing you don't already know if you've read through Vetter's site.

But I want to emphasize using CAD (cardboard aided design) because it's quick, practically free (tape costs a bit), and relatively fast way to come up with fairings you can test before building "good versions".

Highly recommend TUFT TESTING your work before committing to a design. I've seen more than a couple of members here put hours of work into aero projects without tuft testing, and then end up disappointed when the mod doesn't appear to work well.

I hear a lot about the great mileage the KZ250 gets. Personally, I think there is something very special about a 125s bore and stroke. The KZ is just 2 of them which could help explain why it is so good. You have probably seen that I am very specific about conditions. "Vetter Conditions" are 70 mph, into a 30 mph headwind, with a good load, (I like 4 bags of groceries) sitting up and comfortable. It needs to be our first choice in a garage full of vehicles.
Will you be operating in these conditions?

It is really important to document the mileage are you getting now, before you make changes, in these conditions. Can you do that and post the results? Can others with Ninjas document their fuel consumption in the "Vetter Conditions"? This will go a long way in helping us understand the results of the streamlining we come up with.
Craig Vetter

It's neat looking. I'd be worried about the effect of high speed winds getting between the front 'faring' and the 'fender' (Not real sure what you'd call them on this)

My 08 FZ1 seems to be rather particular, when I rode w/o the faring once WOW, it was far less stable.

I also second tuft testing for the same reason MetroMPG said. (;

I would say another way of testing is also top speed runs, but unless you have your own track thats illegal. And always dangerous.

My 250 topped out at 110 mph or so but that was on a good day.

Do you plan to carry passengers?

Craig,

I appreciate the comments from you. You can view my ongoing fuel economy log in my main thread here: http://ecomodder.com/forum/showthrea...50-a-8686.html

Craig's a genie... say his name enough times, and he shows up to speak. ;)

So, theycallmebryan -

Wire coat hangers can be wrapped togehter to make a nice sub-structure for a skin to be applied to. Or, you could get fence wire from a farm store, if there's one near you. That stuff is fairly stiff, as well.

Let's not forget that coastdown testing (A-B-A) is another quick, easy and relatively controlled way to compare fairings which are easily installed/removed.

It won't directly give you MPG figures, but it will give you an answer about whether "A" or "B" is better.

http://www.velomobiel.nl/allert/Recu...n/image074.jpg

I just came across this man's project in streamlining a Honda Innova 125. I had seen this months ago, but figured i'd add it to this thread for further discussion.

De ligmotor

The thing i like about his design is that hes sitting in a recumbant position and the fairing slides forward on rails so that he can exit. He noted that side winds up to 40mph weren't much different than an unfaired bike.

Wow!! I really like that! So many faired production bikes go for either a forward crouch RR position, or a full upright touring position, It would be great if recumbents got more recognition as viable instead of "geeky". My recumbent experience is with bicycles, and it's been nothing but positive. It's so much more comfortable, and you present so much less area to the wind. The major downside is that you have to stick flags on poles to be seen by people in SUVs. And since my head is at about bumper level on a lot of those vehicles, I do want to be seen.

Thanks for the link. That's really informative.

De ligmotor

Agreed - great link. Lots of good info there. Thanks for posting.

That's a great link and a wealth of knowledge!

Hi thatguitarguy,

I really think you are on to something here....

If one wanted to build a really aero motorcycle (I have ridden since I was too young to have a license), then starting with recumbent based on the Gurney Alligator would be my first choice.

The Alligator sits lower, so the CG is lower, there is less side area for inevitable side winds to grab hold of, and makes the frontal area less, for a better CdA.

Take the Gurney Alligator, sit as low as you can before your butt touches the rear drive chain, extend your feet forward, and then work your magic with the body panels!

I have an old Honda VF500, and would do exactly that to the bike if I were going full out with two wheels. Making the foam/fiberglass panels would just be icing on the cake!! For me, that's the fun part.

Look forward to seeing what Brian comes up with.

Jim.

This isn't my project, I'm just following along.

I had to google the Alligator, because I'd never heard of it.
Dan Gurney's Alligator motorcycle - Road Test & Review - Motorcycle Cruiser
With an MSRP of $35,000 for the Alligator, I think that little Dutch bike is more my style.

So i showed my girlfriend pictures of my ideas and she said " (Sigh) You'll look like a complete idiot." I responded "(chuckling) Why?". She replies "You'll look like a mouse."

Just a funny tid bit :) . Shes now sitting next to me giving me the eye....

That's funny. I was just looking at the Dutch bike, and thought that once he installed the mirrors, they look like Mickey Mouse ears.
http://ecomodder.com/forum/member-th...mouse-ears.jpg
Once the price of gas spikes again, I'm hoping to see a lot more mice on the road, and a lot fewer monsters. The elephants should fear we humble mice.

Hi thatguitarguy,

No, I understand. You know how it goes sometimes, where your conversing about something, and someone else throws in an idea, and then first person throws in something else, and viola, you have an excellent idea floating about...

Well, that is what happened to me when I saw your post about the recumbent style seating, which allowed me to recall the Alligator, and I threw that into the pot for Theycallmebrian to consider.

And, no I did not intend for anyone to actually *purchase* the Alligator, but simply, shall we say, *utilize* some of the major design concepts.

Since Brian already has a fine set of wheels, maybe he would consider *altering* the shape of things a little...

.... All part of the design process....

Jim.

I saw a phone book earlier today with a computer mouse on the back... it had a guy sitting in it with a aero windshield and it actually looked quite streamlined. It was odd. Maybe someone should build one? :)

The "Alligator" bike -

Looks like someone took a bike from OCC and added a fairing and turned the ape-hangers back a bit... I like it!

Brian,

My wife gives me the same look. LOL :)

And I respond, "It's just the engineer's curse"!!

Jim.

From the streamlined bike page:
I guess that's a warning for ya!

Coincidentally, Googling "Slipster" places this page in the search results at #5.

:thumbup:

One ball bearing on the ground - less RR!:thumbup:

You know your on to something here...

About 10 years ago, I had the crazy (cool) idea of covering the entire front wheel on the Honda VF500 with a small foam/fiberglass fairing. Similar to a Suzuki Hayabusa, but with *full* coverage. Just a portion of the tire sticking out next to the ground.

And after spending a large portion of the winter working on it in the basement, I was delighted to find out it worked great.... As long as I was not behind a semi trucks draft....

It turns out the air turbulence coming off the back side of the semi trailer creates a buffeting air movement at about 4 Hz.

....It also pretty much meant that I had about zilch for handlebar control of the front wheel while in that draft....

Needless to say, the beautiful and delightful front wheel fairing disappeared from the motorcycle, never to return.

Jim.

I plan to extend the front fairing over top and around the front wheel, not have it actually attached to the forks.....much like you see in the aero recumbent on the previous page.

The problem seems to be that turbulence is causing instability in the steering when a fairing is attached to the forks. Air hits this rotating object and simply wants to move it.

Well, I was mostly referring to CAD design before really using materials, but the front wheel thing is a lesson well learned as well. I ate dirt road for nearly 500 feet on a pedal bike because I lost front stability.. I don't think I'd ever do anything that intentionally caused the effect.

I think you are going to have "weathervaning" problems any time you increase the lateral surface area of anything on the front fork, whether it be a wheel fairing, or even a headlight or headlight fairing. These should all be mounted to the frame - not the fork. The balance and control of the bike are dependent on your relationship with the front wheel through the fork and bars. It's strictly 1:1, with no mechanical advantage or separation like in a car. And when you try to shorten the bars for better aerodynamics, any problem is going to be more pronounced.

http://www.blogsmithmedia.com/www.au...motorcycle.jpg
This may look cool, but I think that any turbulence is going to be amplified by all that extra surface area on the front wheel.

http://www.velomobiel.nl/allert/Recu...n/image074.jpg
Here the front wheel is protected from those turbulent forces. The frontal area may be larger, but control of the bike is paramount.

The great thing about designing bikes is that it costs a lot less money than designing cars, and you have fewer rules and regulations that you have to deal with in getting it on the road.

You may be able to shortcut the laws of man - but you still have to abide by the laws of physics. And what you don't pay for with money, you may end up paying for with your body if you don't get it right the first time.

Just trying to make a plan of attack for this project. Tomorrow i think i'll pick up the framing supplies and try to find some cardboard for some CAD testing. I figure i can start by making the frame adjustable (ex: Be able to elongate the tail if i need to), overlaying cardboard, and tuft testing to find a good shape.

Let me see if i have this right:

From what i understand, the objective for stability is to keep the center of pressure behind the center of gravity, if possible (this is Rocket Science!). The Center of Pressure wants to follow the Center of Gravity through the air. The entire mass will want to rotate around the center of gravity, so having that more forward would be beneficial for stability. Also, it seems that the more you can separate the distance between the CP and CG the better because variances in turbulence across the fairing would try to turn a shorter distance faster (harsher).

So if i have this correctly, i want to choose a fairing shape that will keep the CP as far back as possible while maintaining an aerodynamic shape.

Today I did some measurements on my bike. The fairing at the widest point will be 32-34" wide at the handlebars in order to give me about 2-3 inches of room on the sides of the bars. From the handlebars back will be the tail section. With this in mind, i tried to find a good shape in DesignFoil. I figured that the chord width will be a 30% profile,which would make the fairing about 9 1/4 feet long (A total extension of about 3 feet).

In DesignFoil, i tried to find a shape that in itself (in a 2d world), had a Cd under .01 with a chord of 9.5 feet and a width of 30%, all while having a CP as rearward as possible. It seems like the NACA 0030-93 looks like the best bet. It indicates a CP of about 88% the chord length.

http://i422.photobucket.com/albums/p...ACA0030-93.png

So i took this shape and overlayed it on a top view of the Ninja and this is what it looks like.

http://i422.photobucket.com/albums/p...ayedonbike.png

What do you guys think of this?

Also... I was thinking about the Side view of the bike, and it came to me that MOST of the air ill be pushing through will travel to the sides of the fairing and not overtop. Would it be safe to say that the shape of the side view doesnt matter TOO much? I know a 10-15* taper from the back of my helmet to the edge of the tail would be beneficial.

Would it be better to have the bottom half of the fairing the same exact shape? Here's what i mean visually.

http://i422.photobucket.com/albums/p...viewbottom.png

So in other words, that whole black area (in side view) would be the NACA 0030-93 shape (in top view).

What do you guys think?

Fully Faired front wheel
 

I thought De Ligmotor should have kept the full fairing for rain and foot protection inside the fairing. He says he kept some of it to keep his feet out of the wheel but he's going to get some wet legs if he rides that in the rain. I can tell you that there is a lot of water that sprays out sideways after it impacts the fender. If the fully faired wheel is inside the outer fairing it shouldn't affect handling adversely even in crosswinds. The wind can't get to it, right? Inspiring work though, great link:thumbup:

He's clearly a smart guy. It won't take him long to figure out that he'll want that front wheel enclosed inside the fairing. It'll be interesting to see how he encloses the suspended front wheel. That'll help to quiet it down a bit. I'd think that eventually he'd want to isolate the noise of the engine also, but he'll still need airflow to cool it. His helmeted head is above the fairing, but still the noise inside that thing must sound amplified.

It is a great link, and I hope he keeps it updated for us vicarious inventors.:)

I think you're right about the air traveling much more around the sides than up and over the bike. It's different in a car, because the car is so wide.

I think that the NACA shapes are a good starting point, but don't be locked into it. Be ready and willing to change your shape as tuft testing with your CAD fairings as more guidance than NACA theory.

And the first thing I'd be wary of is the length after the rear wheel. You're not making a straightline Bonneville speed bike, and with that short wheelbase, you're looking at some handling problems. I'd chop it off not far past where your photo ends in a Kamm shape, or at the very least, have a sharper upsweep, and bring the tail into a cone shape, rather than a fin.

You see the longer boattails on cars because of the inherent stability of 4 wheels on the ground. Having a long tail on a bike is going to give you the same type of weathervaning problems as an independently faired front wheel, especially with that short wheelbase.

Take it slow, use a lot of cardboard, and be very ready to change your design if it doesn't feel stable.

Stay safe!!

Brian,

Here is confirmation that you indeed, do not want to add a fairing to the front wheel by itself...

... The fairing around the front wheel needs to be supported by the frame...

Ask me how I know!!

Picasa Web Albums - jsmosher - Motorcycle-Fa...

Needless to say, the beautiful work on the front fairing did not last. The fairing however, is still going strong.

P.S. It took a while to find these old photos from 1988.

Jim.

You might also consider borrowing from modern bicycle technology:

http://www.lightningbikes.com/sf40blu.jpg


Lightning F-40: World's Fastest Production Bicycle

So i was doing some modeling in Blender to see what this beast would look like using a NACA 0030-93..... and MAN it looks so cool!!!!!! I still have to add a tail section, but everything in this picture is exactly to scale how it would be on the bike (of course, with smoother edges). I could have added a couple more vertices on the top of the canopy to make it smoother, but you get the idea.

http://i422.photobucket.com/albums/p...n/Sideview.jpg
http://i422.photobucket.com/albums/p...rlowerview.jpg
http://i422.photobucket.com/albums/p...yan/render.jpg

And a rider view shot! :D
http://i422.photobucket.com/albums/p...ockpitview.jpg

Heres a side view showing a picture of me on the bike behind the model. You can see where my head is oriented in relation to everything.
http://i422.photobucket.com/albums/p...lenderWork.jpg

Ok i finished the tail modeling.

http://i422.photobucket.com/albums/p...rTailFront.jpg
http://i422.photobucket.com/albums/p...ilFrontTop.jpg
http://i422.photobucket.com/albums/p...erTailRear.jpg

http://i422.photobucket.com/albums/p...enderWork2.jpg

I dont know about you guys, but i think this mock up looks absolutely BEAUTIFUL.

One thing to note: in that model, the dimensions are base on me sitting on my bike with the suspension compressed in an idle state. I dont think i would be able to have the underside of the fairing that low to the ground as it is in the model. Ill have to do some testing to see how low my bike can get with the suspension fully compressed.

Now i have to figure out if i can get this model into SolidWorks for some CFD testing :D

It looks like a blimp that was stretched in Photoshop with 2 wheels below it.

I don't think a flat front end is 'ideal' shouldn't it be more rain droppish?

http://i422.photobucket.com/albums/p...n/Sideview.jpg

Looks like a pointy baby carriage in reverse.

Sorry.;)

It would be pretty hard to cover the bike inside with a teardrop shape, and blunt in front is good.

I'd still be concerned about the length of that tail, though.:eek:

Refer to Mr. Vetter's "Rifle" body fairing.

The nose isn't quite blunt in that design, but the wind isn't really concerned about where it separates, so much as how it comes back together.

While a more rounded nose would be more "ideal", the design doesn't lend itself to use in this case, at least not as easily.

I'm sure there will be refining and tweaking as the design goes from digital to real.

Chopped tail anyone?

http://i422.photobucket.com/albums/p...hoppedtail.jpg

http://i422.photobucket.com/albums/p...oppedtail2.jpg

A blimp is aerodynamically designed for its purpose. Cool!

About the front end bluntness, i had mentioned this a few posts back. Most of the air will flow to the sides of the fairing since that is the most parsimonic path. Motorcycles are taller than they are wider (opposite of what you would find in most cars), so more concentration should be made on the sides of the fairing than the top. Having a blunt front end is not necessarily detrimental, and as Christ mentioned, its the ass that matters :thumbup:.

That having been said, these pictures are a first take at a possible plan for the fairing. I will try some other things to improve the aesthetics.

It looks safer. But just chopping it off so abruptly leaves a good sized void for the air to rush in and pull you back. I think if you tighten your taper before the rear axle a little bit you can bring all the surfaces much closer together, still within that framework, and keep enough air attached that you won't have nearly as big a void. It may seem like a compromise, but safety shouldn't be compromised. Good work and good luck!:thumbup: