Introduction & Cross wind solutions to motorcycle Streamliners? - Page 3 - Fuel Economy, Hypermiling, EcoModding News and Forum

Teri_TX · 03-04-2014, 08:16 PM

Hi P-hack,

I didn't mean to imply your were trying to start a helmet safety thread hijack but I wanted to throw ice water on anyone trying to. This thread is about cross wind aerodynamics and possible solutions.

I'm glad you think a Honda CBR250R is good possible base. From my search of cycles, it seems to be the best for a number of MY considerations. I have been studying how to minimally modify it by hacking off the rear frame and changing the airbox to allow a lower seat.

Back to Cross wind solutions to motorcycle Streamliners?

-- Teri

Quote:

Originally Posted by P-hack

I wasn't trying to start a helmet safety thread, I use mine for comfort in the winter and rain, and like to feel the wind in my hair in the summer, it's like a convertible

P-hack · 03-04-2014, 08:25 PM

I dunno, probably the "best" solution, since a streamlined bike is like a cantilevered wing in even a bit of crosswind is some sort of high up control surface in the tail (nose?) plus appropriate consideration of the torque moments and demands on the traction points, plus some way to control it under various conditions. "fly" it (vertically) through the crosswinds.

Teri_TX · 03-04-2014, 09:38 PM

Hi P-Hack,

Are you suggesting active counter measures like "fly by wire". I had thought of this in a moment of madness. If we had military or NASA budgets, that might be a possible solution. Think of the F-117. Besides, do we really want a bunch of code monkeys designing active control systems for our streamliners? Fighter jocks volunteer and get paid to risk their lives on monkey code. Unfortunately, if you fly on a modern airliner, you're a potential victim of bad code. I haven't flown since before 11 Sept 2001 and don't plan to. Apologies in advance to the real code monkeys among the readers.

Once, when I was looking at Vetter's long tail, a trim tab came to mind but he routinely rides through areas of rapidly shifting side wind directions, a worst case situation. A trim tab may be an option for some conditions but be aware of situation changes!

I have tried to think of how an active spoiler system could be implemented but nothing remotely simple comes to mind. Stall strips are the simplest solution I presently know of. Remember, K.I.S.S. (Keep It Simple, Stupid)

Passive automatic means are best for reliability in the real world.

-- Teri

Quote:

Originally Posted by P-hack

I dunno, probably the "best" solution, since a streamlined bike is like a cantilevered wing in even a bit of crosswind is some sort of high up control surface in the tail (nose?) plus appropriate consideration of the torque moments and demands on the traction points, plus some way to control it under various conditions. "fly" it (vertically) through the crosswinds.

P-hack · 03-04-2014, 11:30 PM

I hope you are not calling me mad or stupid... You wanted this to be an intelligent discussion, that is the intelligent approach, and I doubt even a million monkeys with a million keyboards will stumble on the right code.

P-hack · 03-04-2014, 11:52 PM

But if you are a software luddite (2014, hello!!) there may be passive control possibilities using control surfaces too.

Teri_TX · 03-05-2014, 12:20 AM

Hi P-Hack,

I'm not a software luddite but having done some programming in my career (only as a side activity as a design engineer), I am fully aware of unknown software bugs and their unintended consequences. I know and have known code monkeys who are clueless about what they are really trying to do. Beautiful and gorgeous GUI's and artistic code are more important than true functionality. Example, Airbus knew how to control their A330 with the loss of air speed indicators and their instructors know the procedure. Now, why wasn't that procedure automatically offered to the (inexperienced) co-pilots of AF447 by the software (SW)? The control software just bailed out when they needed it the most. There may be extenuating reasons but I have a hard time imagining I'm the only one that sees what should have been done. I wonder if the latest version of the SW has fixed this?

Enough of this thread drift unless you can offer how it can be implemented.

-- Teri

Quote:

Originally Posted by P-hack

But if you are a software luddite (2014, hello!!) there may be passive control possibilities using control surfaces too.

PeterS · 03-05-2014, 12:21 AM

I've been chatting with Teri on this subject and am of the opinion that for the kind of riding I normally do ANY tendency to veer from a fluke cross wind would be very dangerous. In heavy highway traffic big rigs generate very complicated gusts . Having a sudden lift applied in that situation would not be good.

I've come to the conclusion that a straight sided fairing ( no convex surface) but with a flat taper to the rear might solve this problem but at the cost of aero efficiency.The front would have a wedge shape vaguely reminiscent of this photo posted earlier http://bikeweb.com/files/images/royce-578.preview.jpg .
Gentle rounding to reduce drag but no convex surfaces . As can be seen in the photo, the flat sided shape lends itself quite well to closing "doors" on the sides but probably with foot opening down low.