Just joined the aerodynamic crowd.

[JeffM]

Vic Valdez brought me a little gift today from Alan Smith - A couple of Alan's old aero parts.

I plan on cleaning up the parts I just attached, changing the gearing, and making an aero tail for the bike.

So far:



Took it for a short check-ride around the neighborhood today and nothing fell off and there is a very clean pocket of air behind the screen.



Jeff

[choneofakind]

Cool!

[fr1dayn1ght]

i dont even...

[Daks]

Sure, why not

[LNasty]

all I can say is wow

[CC Cowboy]

I bet you look good on that!

[Panda]

Looking forward to hearing your results! Are you going to baseline your MPG and then record the changes as you make modifications?

[Joshorilla]

You don't look in the least bit silly with that on your bike, infact, I am sure it makes all the women within a 100ft radius moist, and if they are lucky enough to be within a 4ft radius they spontaniously contract a case of pregnancy by virtue of how sexy your bike now looks.

[Ytse Frobozz]

You should get tiny, barely legal (tee hee) side mirrors and put on a rear view camera to reduce drag!

[LNasty]

not far off from getting bike to look like this...

[LNasty]

the you could get this sweet inflatable Helmet...

[JeffM]

You should get tiny, barely legal (tee hee) side mirrors and put on a rear view camera to reduce drag!

I'm planning on smaller mirrors attached to the windscreen. The stock mirrors are a wee bit barn door like.

I am sure it makes all the women within a 100ft radius moist, and if they are lucky enough to be within a 4ft radius they spontaniously contract a case of pregnancy by virtue of how sexy your bike now looks.

Yep, happens without the bike anyway.

Looking forward to hearing your results! Are you going to baseline your MPG and then record the changes as you make modifications?

I average 50mpg stock - Commuting, freeway and canyon runs. I'll be checking at next fill up to see if there is a difference.

not far off from getting bike to look like this...

The Colani-Egli MRD-1: The Colani-Egli MRD-1 produced 320hp from its turbocharged, nitrous-breathing engine, and broke the World Land Speed Record for 10km from a standing start, at 170.26mph (272.41kmh); his top speed was 330kmh (198mph). The record was previously held by the Honda ELF, with full Works support of rider Ron Haslam (265.4kmh).





Thanks for the comments.

Jeff

[JeffM]

Originally Posted by LNasty

the you could get this sweet inflatable Helmet...

I know my bike is weird but WTF that air bag helmet is really weird. I suppose it goes with her riding gear.

[LNasty]

Lol, just giving you a hard time. I actually wish I had a shield like that for riding on interstate, the wind kicks my a#@ some days

[JeffM]

Originally Posted by LNasty

Lol, just giving you a hard time. I actually wish I had a shield like that for riding on interstate, the wind kicks my a#@ some days

I haven't taken it on the interstate yet but up to around 55-60 it seems fairly calm. I may use a little piece of Lexan as a adjustable tab on top of the screen to change the airflow just a bit. When I place my hand there it kills a little rumble of turbulence just off the top of the screen.

This is what Craig Vetter did:



Jeff

[JeffM]

I rode my bike it some crosswinds and the additional surface area makes it a little twitchier in gusty conditions. 20mph side gusts cause the bike to skate to the side a bit. Nothing scary, but noticeable compared to the stock bike.

I believe the only way to calm down the cross wind skating is to take off the front wheel cover or add a tail. Since my goal it to increase aerodynamic streamlining, I will go with a tail. I may first try a Kamm tail vs. a full boat tail because it will make storing the bike a bit easier. A Kamm trailing edge reduces aerodynamic drag by tricking the air into thinking a trailing edge of a shape is longer than it is.

Speaking of air flow, it is amazing how a small change can cause a noticeable result. Point in case: I did not like the rough edge on the lexan screen so I added some windscreen edging material. I ended up taking it off as the little-tiny lip it added caused a very distinct rumbling noise.

The Kamm effect from http://www.tonyfoale.com/Articles/Aerodynamics/AERO.htm:

[JeffM]

I got to work on the tail section. After a little CAD (Cardboard Assisted Design) work I have created the main and tail bulkheads. I am using 1x2 stringers to tie the bulkheads together.

This is a small start and only took an afternoon to accomplish. I decided on a simple wood structure, well, because it is simple and I have the hand tools to accomplish the work.

I will cut lightning holes in the bulkheads and will be using steel supports to attach the structure to my bike. I am attempting to keep the stock seat in place.

[Ytse Frobozz]

I would just paint a smiley face on that board and call it a day.

[JeffM]

[BRad704]

I like where you are going with this.

but as an honest question... Do you think the additional weight of the wood and steel tail will negate any gains from the smoother airflow?

[JeffM]

Originally Posted by BRad704

I like where you are going with this.

but as an honest question... Do you think the additional weight of the wood and steel tail will negate any gains from the smoother airflow?

Thanks.

Craig Vetter weighed the tail parts removed from Alan Smith's 250 and they weighted 17 lbs. I figure after I add the tail my net gain in weight should be around 20-25 lbs on the tail and a few pounds at the nose. Now, by adding the tail I can get rid of my saddle bags so I will lose a couple of pounds there too.

The big chunk of plywood in the photo will be lightened by cutting out the entire center leaving only a 2-3 inch border. I will face the front side with 1/8 inch ply. I currently plan on skinning the tail with 4mm fluted plastic sheet. That could change.

So I will gain 20-30 lbs of additional weight. However, if I can increase my mileage to around 90-100 mpg via gearing and aero-mods I still think I can come out ahead.

Plus - it is fun to try

Jeff

[BRad704]

I'm first-in-line to applaud you making it on your own! I love making 'stuff', just for the fun of creating.

Have you thought about the heat-shrinking plastic sheeting? Like what they use for ultralight (airplane) wings and tails. Requires a good skeleton, but could work well for light-weight.

[JeffM]

Yes, I have thought of that and shrinkable plastic would be a light, elegant, solution. I used to fly R/C gliders so I know exactly what you are talking about.

I am trying to get the bike together for Craig Vetter's October Fuel Economy Challenge so I am trying to do a quick n' dirty build. Might be a great idea for later.

Thanks, Jeff

[gantt]

looking good. I am tuned in to stay up to date on your project!!!

[CynicalC]

Why steel over aluminum or any other durable lightweight material?

[IF13]

In all honesty, it looks fine. Makes you look really serious about commuting or doing some long distance riding on that bike.

[JeffM]

Originally Posted by CynicalC

Why steel over aluminum or any other durable lightweight material?

I'm leaning to make the main supports strong vs. light (at least initially). Last thing I want is the tail to work loose while on the freeway. I'd rather over engineer initially.

I may use aluminum for some of the lesser supports. I am going to try to use mounting locations that are already on the frame vs. creating my own.

[Samer]

I highly doubt that piece of wood will help to reduce drag. In fact, I'm pretty sure it will increase drag. It should be fairly easy to test it if it is easy to remove and replace it.

I looked up the Kamm effect and all of the examples show cars having an airfoil shape that gets cutt off, like the image you shared. However, in your case you're just adding a flat plate somewhat offset from the body. Flat plates normal to the flow have pretty much the worst drag coefficient of any shape.

[Motofool]

Originally Posted by JeffM

...........I believe the only way to calm down the cross wind skating is to take off the front wheel cover or add a tail..........

Jeff,

Great project !!!

The worst surfaces for crosswind are the transverse ones higher respect to the contact patches and more aft respect to the steering column; for that reason, I believe that you will not gain anything by removing the front wheel fairing.

This video is not an animation but real wind tunnel demonstrations:

Link to original page on YouTube.

[JeffM]

Originally Posted by Samer

I highly doubt that piece of wood will help to reduce drag. In fact, I'm pretty sure it will increase drag. It should be fairly easy to test it if it is easy to remove and replace it.

I looked up the Kamm effect and all of the examples show cars having an airfoil shape that gets cutt off, like the image you shared. However, in your case you're just adding a flat plate somewhat offset from the body. Flat plates normal to the flow have pretty much the worst drag coefficient of any shape.

You are correct. Having a single bulkhead behind me would cause a ton of drag. However, I am building a boat tail from that bulkhead back.

Like this:

[JeffM]

Hernan great vid

I lightened the main bulkhead, test fit some stringers, and played around with the cargo shelf.

I priced corrugated plastic board and .032 aluminum: 4X8 sheet of the fluted plastic is $13 and a 4X10 aluminum sheet was $45 (I think). I am leaning toward the aluminum.

Next: Mount the main Bulkhead.

Photos (ignore the extra long stringer sticking out the front of the bulkhead it will be cut off) with a grocery bag to check if 4 of them will fit in the area per Craig Vetter Challenge rules :

[Motofool]

I wonder what your neighbors think about that project

[Sipper']

I'll be intersted in seeing how it works for you. I bought my 04 with a project in mind but enjoy riding it so much I have kept mods limited to suspension/lighting.

Lifetime average (since Nov 2012) is 73.8 mpg.

[Samer]

This is quite ambitious. It reminds me of the aero civic

http://www.aerocivic.com

[JeffM]

Originally Posted by Motofool

I wonder what your neighbors think about that project

So far -

And a little of this -

[JeffM]

Originally Posted by Sipper'

I'll be intersted in seeing how it works for you. I bought my 04 with a project in mind but enjoy riding it so much I have kept mods limited to suspension/lighting.

Lifetime average (since Nov 2012) is 73.8 mpg.

I absolutely understand. Having the bike ripped apart is really cutting into my riding time. It has crossed my mind to throw it back together and just ride.

Nice average

[JeffM]

Originally Posted by Samer

This is quite ambitious. It reminds me of the aero civic

http://www.aerocivic.com

Thanks. Lots more like that over at http://ecomodder.com/

[Panda]

Can you create an enclosure for you to sit in? If you can keep the airflow smooth from the front to the rear and enclose the cockpit you'd get the benefits of the less turbulent flow off the boat tail without the attendant drag penalty of the vertical piece behind you.

[greenaero]

Jeff, Good Progress! But The Vegas Vetter Challenge will be here before you know it. Have you changed your gearing yet?
Alan says if you use aluminum to skin it go with.020" thickness, otherwise it will get too heavy. keep up the good work!

[JeffM]

@Panda No full enclosure. Actually, having the gap allows the airflow to cross-over and kill any lift to either side which makes the bike more stable.

@greenaero Hi Vic. No, have not changed the gearing yet. What would you suggest to start with? 15/39- ish?

Hmmmmmm, .035 is too heavy. Coroplast may be the way to go. It is very light light. How did you attach your skin to your bulkheads?