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Old 11-24-2008, 04:55 PM   #1 (permalink)
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Aerofairing for a sport bike, Design and Creation

I am plannning on building a full aerofaring for my SV650s. it will cover most of the front wheel, most of the rear wheel (bottoms only open), and should be very aerodynamic when I am in a tuck position.

I would also like to be able to regulate where the hot radiator air goes, in the summer I would like it to vent out the sides of the bike and away from my legs, in the winter I want it to warm my legs, this should be an easy moveable panel.

creating some airflow to seat to, well, blow cold air at my butt would also be just awsome for hot summer days.

I want to integrate storage into the fairings, so I can stow a spare helmet, my boots, my jacket and pants, lunch, a rainsuit, and other such stuffs.

It should be easy to mount and unmount, and not require much in the way of "ghetto" supports, it should support itself off the frame of the bike. I wanna make it out of fiberglass or carbon/kevlar if I find the cash.

I have full access and a pretty good mastery of autocad (its sorta been my job for many years now) so I can design it and print sections for easier building (print section onto paper, glue paper to foam, cut. also allows for me to layout peices on a board to find the obtimal cutting patterns to fit parts inside parts and then assemble like a puzzle).

this is the begining, there are no pictures or concept drawings or flow testing yet. there will be. I am hoping to have help from some here who know their flow testing software (we dont do that here) and have ideas on strength or constructability. I will also present my ideas and designs for scrutiny and for you guys to have fun with.

my goal MPG with all this: no idea, the bike gets from 45 (riding HARD and to redline) to 55mpg right now, is a 650cc 90degree twin with water cooling and fuel injection.

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Old 11-24-2008, 06:49 PM   #2 (permalink)
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For starters I would check out Craig Vetter's Freedom Machine. Go to the bottom and read the "Follow the progress on my own Freedom Machine". It is very informative and he talks about the process and mistakes and redesigns along the way. I believe he still sells the fiberglass Rifle streamliner body that you can possibly modify to fit your needs.

Freedom Machine intro
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Old 11-24-2008, 07:06 PM   #3 (permalink)
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Very interested in your project. This is exactly what I would do if I had an extra 5 hours a week, but I'd use a Kawasaki Ninja 650 or better yet 250, just cause I like 'em. Your SV will do quite well anyway but be sure to address gearing and cam timing to optimize the engine efficiency at higher speeds. Doing this alone should net you 65mpg+ in current form.

I think the project you and Craig Vetter are undertaking have great potential. Not sure why Craig isn't getting the mileage he should. Something tells me the Helix 250 drivetrain, though capable, is not optimized for highway speeds.

Good luck and go forward with this. Blaze the trail for all of us that want to do it someday. We'll be watching...
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Old 11-25-2008, 10:32 AM   #4 (permalink)
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Originally Posted by beatr911 View Post
Very interested in your project. This is exactly what I would do if I had an extra 5 hours a week, but I'd use a Kawasaki Ninja 650 or better yet 250, just cause I like 'em. Your SV will do quite well anyway but be sure to address gearing and cam timing to optimize the engine efficiency at higher speeds. Doing this alone should net you 65mpg+ in current form.

I think the project you and Craig Vetter are undertaking have great potential. Not sure why Craig isn't getting the mileage he should. Something tells me the Helix 250 drivetrain, though capable, is not optimized for highway speeds.

Good luck and go forward with this. Blaze the trail for all of us that want to do it someday. We'll be watching...
yeah you need a certain amount of power to go fast. plus he cant really swap out gears nice and easily, I can. I can run a 17 sproket up front and a 44 in the rear, right now I am at 16front 45 rear, which is up from 15 front stock and 45rear stock. it would just lope along at that speed. the engine will lug pretty easily below 3,000rpms but 3500-5500 is a nice sweet spot.

I will be doing it quite a bit different from vetter though, he thinks his thick aluminum and plastic version is light, but not as light as a thin fiberglass shell. he's also designing his to work when he's sitting straight up, mine will only be slippery when I am tucked, this has a couple reasons:
1. I like to tuck, all my weight is held on my butt and chest and none on my hands, its really comfy.
2. I want to regulate the airflow over my body, when its hot, I want lots of air hitting me, when its cold, I want none hitting me, this is easy to accomplish if all I have to do is sit up.
3. my bike rides really nice tucked or sitting, either way, so why not use both?

my design will also be a fair more attractive and easy to bolt on when done, without any frame mods and all as 1 peice.
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Old 07-05-2009, 05:14 PM   #5 (permalink)
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Old 07-10-2009, 03:08 PM   #6 (permalink)
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Excellent idea and bike to use, esp. the engine and handling. I've considered such as a replacement for my BMW bikes due to better weigh and handling from the Suzuki.

For starters, use flat-wrap Coroplast sheet, bent into airfoil leading edge shape, with vertical alignment. For exit vents for the radiator study fish gills, and exhaust the spent cooling air out the sides. Bernoulli/Venturi will draw the air through the rad. and out. A simple flapper valve could be used in winter to vent the radiator air onto your legs, but out the sides during summer. The radiator on that bike, btw, could be turned 90 degrees so its long axis is vertical, for reduced frontal area.

The front wheel could stand improvement in the fender. Some of the companies that make aftermarket stuff for Bonneville racers may have a bolt-on replacement fender that is suitable. However, too much coverage will get you squirelly handling in crosswinds, so don't get too carried away with the front wheel fairing.

For bottom and top caps for the airfoil, consider free-blown vacuum forming techniques, as seen on YouTube.

Keep in mind that punching a clean hole in the air is only half the battle--you need a smooth and proper trailing edge fairing behind the rider and machine so the airflow can recover with reduced turbulence.

My son has an unfaired Suzuki SV650, and it gets 50+ mpg @ 70+ mph. With a good full fairing, I suppose mileage would improve by ~50% at that speed.

Got pics of your bike?
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Old 07-16-2009, 12:55 AM   #7 (permalink)
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Hello ditchoto.. I would suggest forming your fairings first on a model. It really doesn't take that much time. A few supplies from your local hobby shop will do the trick. I'm developing one for my Bonneville bike and it started with a scale model like the one posted. I have a pix of the final model that I can't get off my camera at the moment. I don't know how familiar with aerodynamic principles you are but here are just a couple to keep in mind in your design ie: basic air drag, lift, basic directional stability and dynamic directional stability. The more important basis for the model is to have something small enough to scale in order to do some DIY wind tunnel testing. You can use string or smoke depending on how large your model is.
I too drive an SV650s. Great bike and is my daily driver. I used lexan pieces to form some extra faring on my SV for the winter that cuts down on some forward drag and of course keeps me a bit warmer. Living here I drive all year round even though I've driven in 15 degrees, temperatures arn't typically that low. The lexan is fairly easy to form with simple bending and fastening. Heating to form is a bit more difficult, but simple mods can be done with an oven. Google lexan and you'll get a bunch of usefull information. Fastening and supporting is critical.
BTW, I changed the rear sprocket to 43 teeth which made a much more flexible gearing range. Still decent for 1st and 2nd and I can cruise 75 at 5,100 on a straight road. I like to keep the rpms under 6500 at cruise. With an adjustable air box change I can lean out stock jetting for my higher elevation and get 48 to 52 mpg. When I drive in town and use costing and turn the bike off at lights my usual average best is around 52 to 54mpg. I don't baby it much also. Obviously better fairing will increase mpg.
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Old 07-27-2009, 04:58 AM   #8 (permalink)
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I have Vetter's DVD “How they got 470 MPG” and it says a whole lot. In a few words he would say that good aerodynamic forms are rounded in the front, pointed at the back and consist of smooth continuous contours. Trout shaped if you will. No heads, mirrors or tires (limited anyway) sticking out and upsetting the airflow. This combined with light weight takes very little HP to go 60+ MPH. Very little HP equals very little fuel burn.

A great deal of information and the DVD is worth the asking price.
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Old 07-27-2009, 08:19 PM   #9 (permalink)
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Thanks for the response fidalgoman. I've studied Vetters information and he's long got it figured out for street motorcycles and mileage design. For me, running at Bonneville creates different problems of stability with a bullet type design. The model is utilizing ideas from the stealth configurations, if you will, in order to balance down force against uplift. Obviously you don't want any uplift even for the street. The crosswinds are a huge issue for us at Bonneville and just regular driving. Typically wind escapes through open areas over the engine and through the bike. In my design, because of my engine operating temperatures, I don't need much air and so far, in wind tunnel testing, it seems that cross winds over this design seems to add some equalized down force especially if you are already leaning into it as we often do.
yes ideally an actual bullet design is preferred. For the class I'm in and for the sake of keeping some aesthetics to the motorcycle design itself is also the experimentation of this funky fairing idea. The guy who helped with this idea is an aeronautics engineer. Of course the real test is real world driving. So I've got a bit more to do but I've got most of the fairing on the bike. There will be tweeking for sure. You really never know until you try it. Mostly just curiosity prevails.

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