I think I finally figured it out

[Robert]

After much time playing with the air flow on my bike I think I finally figured how to make a small air wing to decrease the flow of air and turbulence on me. Since I put throttle lock on my bike I have had time while driving to play with airflow. Honda really did a good job of directing air on these bikes and I did not think to change the comfort level of the driver there needed to be much of a fairing. Well this weekend while out on a ride I was able to redirect the air flow from in front of the tank up and to the sides. It made a significant difference in the turbulence that you normally feel as the driver.

A short air wing about 1 to 1  1/2 in v on the front of the tank just under the front where the chrome gas cap cover attaches then to the side radiator cover nacelle is enough to direct the air directly up or over and out the side. Basically all air goes around the headlight and from the front into the flat front between the radiator nacelles and then clings to the front of the tank rounds the top of the tank and comes back and hits the driver. This causes the turbulence that the driver feels. If you divert this flow you still keep the pressure inside the driver bubble but stop the direct air hitting the driver and therefore less buffeting.

The air actually goes into the pocket, calms down and maintains a stable flow of air and stops the buffeting.

Now going to try and make something soft, low and able to hold on and bolts to the bike without marring the surface.

It amazes me just how directed and forceful this air flow is, its almost like water rather than air going over the surface of something. You can put your hand above it and feel it go under your hand between your hand and the tank, if you hold your hand about 1 inch above the front curve of the tank.

Cant have anything to high since you do not want to interfere with the handle bars. You still get hit with wind from over the windshield but the air that hits you about stomach up is gone.  

[Bill Havins]

I agree.  And if you'll refer to some of my earlier posts about my fairing build you'll note that I discovered a "half-soccer-ball" sized pattern of turbulence just above the filler cap behind my fairing.  I indicated a desire to build a simple "chin spoiler" or "bib" that would attach to the bottom of my fairing (two 8mm bolts are already there in the bottom of the bottom triple clamp - they hold the bottom of my fairing in place).  I think that a chin/bib, combined with the fairing itself, will "deflate" the soccer ball of turbulence.

Now, I don't think a chin/bib with the standard headlight will do anything much, because there are air inlets on either side of the headlight that will still let turbulence in.  However, a person could block those inlets and not cause problems.

A chin/bib would eliminate the possibility of interference with the handlebars (as might happen if an air dam/deflector is mounted above the tank).  And it might be very easy to fabricate a sheet metal chin/bib just to test the idea.  I intended to do that months ago, but I got a bit distracted by Judy's broken ankle, broken hip, and now knee replacement.  Maybe I'll fiberglass one up during these winter months.

I'm continuing to build my new instrument cluster for my Valkyrie.  It's really quite a deal.  That may keep me from getting the chin/bib built.

Carry on!

Bill

[Robert]

The problem is as I see it is the flat area in front of the bike. Basically the whole area between the nacelles and the lower cowl. Anything on the front forks is really not going to help to much since its the area behind the forks and the total flat face of the bike that acts like a scoop. Why do we have a scoop at the bottom a scoop on both radiator pods and no outlet? That is alot of air to direct. The design of this bike is directly opposite what would be normal wind mitigation on vehicles. Who in their right mind makes the whole front a wind scoop and flat face come on, really?

 The air hits the front and has outlets through the radiator,engine area vents, over the radiators vents between the tank and the radiators on top of them and flow out above the knee so it decompresses the pressure bubble just in the front area between the forks and the front face of the bike. When this decompression occurs it leads to a stable flow of air following the tank like the wing of a plane. You would have to build something along the line of the F6B or Wing fairing since they encompass the forks and this area.

This air dynamic is the exact reason our bikes are not really subject to turbulence like many other bikes and is pretty smooth going along at 80.

A simple demonstration is water coming out of a faucet. Slow the water down to a single stream of water put your finger in it so that the water follows the curve of your finger and is diverted. It will actually cling to your finger but once it does that it is turbulent on the backside. This is what we are fighting. This is the air that hits the face of the bike and then flows over the top of the tank since the rest of the air is pretty well accounted for. No fairing is going to totally stop this since the bottom of the bike is a scoop for air the front lower cowl is a scoop for air and the flat face of the timing cover is a distribution area for the air that comes in and redirected.

For years I had wondered how they ever designed a bike with such a prominent flat face forward and not worry about it and now I know. I would have to say they use a pressure bubble on the front of the bike to smooth things out and use the pressure in this bubble to distribute air to where its needed and to relive the pressure. A Manifold comes to mind.

Any air that is in front of the gets scooped up by this whole lower area pushed upwards and then along with the minimal air by comparison from around the forks gets pushed into appropriate slots like radiators and little openings. This same air being pushed up from the bottom is like that stream of water that you stick your finger in and it clings to. That is why no fairing will totally work because the air is not only from the top but a big scoop from the bottom and pushed up basically behind the fairing. This is also the reason why a small air dam on the front of the tank will stop this air and direct it up or out since that is the direction of travel of the air.

[st2sam]

YEP.
I have owned many bikes in over 50yrs. of riding. The wind management on my Valk is second to none.
And it's the coolest (pun intended) bike I ever rode in Hot weather.
IMO a small or better yet NO windscreen gives the best air flow.

Robert, thanks for figuring it out. 

[Kidd]

I talked  to the folks at Baker air wings about making something that I can mount on the tank , even sent them photos of what I had in mind  , never heard back from them and I did not pursue it .

Still considering a pillow  , something that can be worked into  areas where air is coming from .
A  pillow being  pliable , soft  ,  stuffed in to  the right areas  will stop most of the problem

[Bill Havins]

Robert,

We're saying the same thing.  On my bike the forks are blocked off to the level of the lower triple clamp.  The "half-soccer-ball" of turbulence that appears at the level of my filler cap (and it is very predictable and really not very big) is air that hits the flat face of the engine and comes up behind my fairing.  For my setup, a simple chin spoiler at the base of the fairing would "redirect" air through the radiator scoops as well as below and to the sides of the bike.  I think that would quiet the "half-soccer-ball' enough for me.



To me, it is important to think of wind management on this scooter like you would rigging on a ketch, but in reverse - we are not trying to "create a vacuum," we're trying to "build a directional shield."  And I use the analogy of a ketch because it has two masts and can fly three sails (or more).  Putting a windshield on our bikes is like raising a foresail on a ketch without flying a mainsail or mizzen.  It makes for really funny aerodynamics.  Of course, that's just IMHO.

Bill

[Hot Rod]

WOW ..... Glad to see someone address this . One of the only things I don't care for on this bike ! I'm sure I'm not alone in this but after experimenting with different windshield heights I just can't get a smooth air flow. I always suspected it was coming from around tank area. A small spoiler like that would be great ! Everyone who owned a valk would want one !   

[ledany]

Nope, not for me. I have a french Secdem windshield



and I never thought about this kind of problem at any speed     

@Bill : sorry for your Judy

[Robert]

Robert,

We're saying the same thing. 
Bill

 

This weekend I think I will try and fabricate something to see, since my hands on the tank all the time might lead to trouble. 

Also sorry to hear about your other half is still under the weather.

[Robert]

Nope, not for me. I have a french Secdem windshield

and I never thought about this kind of problem at any speed     

@Bill : sorry for your Judy

Hey did I see a car in the picture, I think there was one but I cant be sure. 

[Adirondack Bill]

Robert, another issue to keep in mind when building your wind deflector is how it will look on the bike. The bike has a lot of plastic on it already. I am sure you won't put anything ugly on your bike. Forgive me but in my opinion, the wind in my face is one of the things I enjoy about riding a motorcycle. I do not want the same feeling you have when traveling in a car.I guess for me, the wind is part of the riding experience. Windshields belong on cars, not bikes. I feel they detract from the looks of a bike.

[Robert]

Robert, another issue to keep in mind when building your wind deflector is how it will look on the bike. The bike has a lot of plastic on it already. I am sure you won't put anything ugly on your bike. Forgive me but in my opinion, the wind in my face is one of the things I enjoy about riding a motorcycle. I do not want the same feeling you have when traveling in a car.I guess for me, the wind is part of the riding experience. Windshields belong on cars, not bikes. I feel they detract from the looks of a bike.

The wind in your face wont change since that would come from over the windshield or just air in the cockpit. Its the air that follows the tank top like a wing and hits you.

It would be a small wing at the front rise of the tank about 3 or 4 inches long, about 2 inches high thats it. Going between the chrome for the gas tank cover to the radiator pod bolt top front. Believe it or not that would be enough to deflect the air that hits the driver and buffets him.