BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

GOTJ started a thread called 'Air Flow Control', and not to steal his thunder, I don't think his title is strong enough to attract the attention it deserves.

I believe as he suspects, that the major source of 'dirty' air we contend with is being forced up from the 2 wells at the front of the gas tank. If you look at them critically, it's like they were surreptitiously designed to annoy the crap out the rider.

My theory is that this air is interacting with the air coming in from the front (over a shield or otherwise) and is creating the very turbulent rumble we all love to hate.

Try it yourselves. Get up to highway speed and put your hand on top of these channels. It gets significantly quieter as your helmet is suddenly in MUCH smoother air. I am quite amazed no-one has noticed this before. What's wrong with you people?!?

I'm going to try cobbling some kind of diverter together & see how it works.

Race you to the solution!

Peter

Peter - be interested in the result of your test.

One thing to consider when moving your hands around - you're changing your body shape/position - which can (BTDT) directly influence how you perceive turbulence. On the CalSci shields - if I moved my head to certain positions - it became much quieter (but I couldn't keep my head there.. it was painful), and if I moved my hands around I could quiet things down, but putting some solid blocks in the same place my hands were didn't have the same effect. The effect was caused by my body moving position.

Good luck and let us know how it works out.

Since I took the hit on the Wudo I propose Peter purchases a wind tunnel set up for more precise testing, we will all be grateful

Dave

PS You may be on to something as I believe the Wudo blocks some of this air you are referrring to.

Carbon Fiber tank well covers from Wunderlich just $500 ea.

Mark.

You may be on to something. I have the Parabellum Scout fairing and with the tall shield (20") there is just a bit of turbulence on the helmet at highway speeds.

We've had a bit of warm weather in San Francisco (as opposed to the usual 58 degree summer weather) and I swapped to the shorty shield (10"). This shield is ideal for me for most conditions other than very cold weather and rain. The air flow hits me on the upper shoulders (6'1" ht) and there is very clean air around the helmet. At 80 mph, I don't have to grip to stay upright like I did with the OEM sport shield. And the earplugs don't have any low frequency beat that happens with the tall shield's turbulence, as light as it is.

I suspect that much of this great performance is due to the headlight fairing portion controlling the air flow.

Here's 2 photos:

http://tinyurl.com/6ffhvk

http://tinyurl.com/y9j7xbh

Bill

Using the short stock flyshield there is no turbulence on mine either, just clean air.

I call it a flyshield rather than windshield as it seems to keep the bugs off the back of the gauges, but I wonder if it is actually doing anything else.

Dan-A wrote:Using the short stock flyshield there is no turbulence on mine either, just clean air.

Have you tried removing it completely? I didn't realize how much turbulence the flyscreen was causing until I ran without it.

But regardless, if there's no turbulence either with the flyscreen or with no screen at all, how can the fuel tank channels be causing the turbulence?

NeilS wrote:... if there's no turbulence either with the flyscreen or with no screen at all, how can the fuel tank channels be causing the turbulence?

I'm certainly no aeronautical engineer, but it seems likely to me me that with no screen, the wind blast obliterates any currents coming up through the tank channels. But with a screen on, there's a negative pressure area behind the screen that sucks the tank channel currents up toward the rider, where, mixed with the currents coming around the sides of the screen, turbulence can be created.

I think that's a pretty good story and I'm sticking with it!

NeilS wrote:

Dan-A wrote:Using the short stock flyshield there is no turbulence on mine either, just clean air.

Have you tried removing it completely? I didn't realize how much turbulence the flyscreen was causing until I ran without it.

But regardless, if there's no turbulence either with the flyscreen or with no screen at all, how can the fuel tank channels be causing the turbulence?

Ah but there is, it's just lower with the flyscreen. It's really bothersome to me when it hits me at ear level (BMW 'Touring' screen). Like ShinySideUp said, it seems to be the convergence of the two airflows that really kicks it up a notch.

All you need to do is look at the plastic lining the back of the recesses - it's beautifully sculpted to catch the air on either side of the headlight and direct it up at the rider. It may not be the only culprit here, but it can't have zero impact, and the 'covering it with your hand' method does produce a positive effect.

I still haven't had a chance to mess with this due to a heavy work schedule, but I hope to soon. I have high hopes this combined with an 18" Cee Bailey will prove to be much nicer on the highway.

Peter

As an afterthought for the nay-sayers, the Wudo and similar fairings seem to drastically reduce turbulence, with shorter windshields than most of us use, and I believe their directing air to either side of the tank scallops is the reason. DDerig, as a new (I'm not jealous) user of one - with presumably very fresh memories of the 'before' condition - would you concur?

I concur Peter, I believe the fairing from the Wudo makes for cleaner air. It's not perfect but it's (the combo of the fairing and the rake of the windshield) better than both the BMW screens (and I liked both screens).


Dave

Frankly the R1200R is a nacked bike and therefore turbulence is to be expected. Suggest riders who cannot stand turbulence and want a lot of wind protection should buy an RT.
My 2 cents worth
Peter

After trying several windshields on my F650GS with limited results I remembered something from my sailing days. I taped several pieces of yarn at various places on the front of the bike and windshield. All I had was yellow yarn and it reminded me of an old Tony Orlando song, but that is another story. The air coming off of the Ztechnik windscreen had a nice curved flow from the sides, well away from me, and the top was going over my helmet. The yarn on the handguards, mirror stems and handlebar cross bar was pointing right at my head! I sewed some rubber tool box liner between the bar and crossbar and mounted an old pair of Tourtech handguard spoilers on the mirror stems. It looks funny and is far from perfect but certainly is an improvement.

Frankly the R1200R is a nacked bike and therefore turbulence is to be expected. Suggest riders who cannot stand turbulence and want a lot of wind protection should buy an RT.
My 2 cents worth
Peter"

I use to ride a naked bike with a nice rounded tank (Yamaha Maxim). There was basically zero turbulence. Wind, yes, but not turbulence.

This particular naked bike (R12R) is dissapointing in this regard. I think a $20,000 naked bike should not be dissapointing. Especially if the manufacturer claims to have a wind tunnel at their disposal. IMHO.

Railbender wrote:After trying several windshields on my F650GS with limited results I remembered something from my sailing days. I taped several pieces of yarn at various places on the front of the bike and windshield. All I had was yellow yarn and it reminded me of an old Tony Orlando song, but that is another story. The air coming off of the Ztechnik windscreen had a nice curved flow from the sides, well away from me, and the top was going over my helmet. The yarn on the handguards, mirror stems and handlebar cross bar was pointing right at my head! I sewed some rubber tool box liner between the bar and crossbar and mounted an old pair of Tourtech handguard spoilers on the mirror stems. It looks funny and is far from perfect but certainly is an improvement.

This is the best advice I have heard yet. I can stop guessing where the wind is coming from. I might tape some to my helmet also and have the passenger in a cage photograph me from each side.
I don't need the special density foam from George (GOTJ) anymore but I bet he can supply me with special aerodynamic yarn for this testing. Thanks for the great advice Railbender.