Genius or insanity : motorcycle hypermiling

[Rikugun]

I give you a lot of credit in the riding department. That takes some effort and skill to counter those kinds of crosswind handling characteristics.

[Extent]

Nice, the frame mounted fairing will open up a lot of options.  You can probably pull some more out of it if you point the nose a bit more so it isn't quite so flat straight into the wind.  I would see if you can figure some way to fashion a belly pan for it as well, there's going to be a lot of turbulence down there with all the exhaust piping and casework.

The final angle on your tail section before the very end looks really aggressive to me, way over 10*.  I'll bet you're getting boundary layer separation there.  You could probably do a string test and find out fairly easily, but I suspect that you need a longer tail with a shallower angle.  Relocating your plate and putting bodywork there blending up into your tail would probably help a lot too, keeping lots of turbulence from getting under your tail section.

Also your windscreen terrifies me  ;D

Nice to see big progress tho, 15% is no slouch.

[QBS]

If I'm remembering correctly, by the early 1950's, "dust bin" racing fairings were found to be such a complete, unfair, aerodynamic advantage that they were outlawed forever by the international race sanctioning body of the time.  The organizations' name escapes me.

Edit: Upon further codjitation, it seems that there was more to the ban than concern for unfair advantage.  It seems that the excellent aerodynamics of the fairing allowed engines to motivate their chassis to speeds that the frame, brake, and tire technologies of the time were not capable of rendering safe.  Hence, the aerodynamic technology was handicapped to match the rest of the design mix.

The ban forced the creation of, "work around", vastly inferior fairing designs, that have evolved into what  we have today.

I think the "dust bin" name was derived by the fairings' supposed resemblance to an English dust bin.  Although, having never seen an English dust bin, I can't say for sure.

The design first appeared in the early to mid 1930's and was very common, almost de rigour, in all classes of motorcycle road racing up until the early 50's when it was killed.

Look for pictures of bike road racing during those years for excellent examples of shapes that were
found to work well.  

[supervision]

  Just read the craig vetter link ,, way cool.

[Extent]

"dust bin" racing fairings were found to be such a complete, unfair, aerodynamic advantage that they were outlawed forever by the international race sanctioning body of the time.

That's the idea, they look a lot more like the streamliner bodies you see today.  The hard part is I assume you don't want to drastically change the riding position, which is really what you need to do if you want to shrink that tail section down to help w/ crosswinds

DV sent me a couple of pics, most are already up on Vetters site, but here's a nice full rez shot from the front.

[fret not]

If you really want to get serious about 'cheating' the wind, find someone fluent with CFD (Computational Fluid Dynamics) to help out.  I stumbled onto a site that was selling CFD programs, it was on one of the Globalspec engineering search engine news letters.  from what they were saying you would need a pretty powerful computer.  We have come so far since the Commodore 64, haven't we? ;) :D ;D

Oh, yeah.  Those dustbin fairings were considered dangerous from all the turbulence and debris (dust, dirt, fumes, fuel, smoke, etc) flying around inside at speed.  Those race cars with the big fans sucking them down to the road were also banned due to the debris they threw into the air, a hazard to the following drivers.

[darkvision]

Thanks for all the suggestions.  Actually the frame-mounted fairing I made is a big improvement over my previous handle -mounted shark fairing with the longer & taller windscreen.  I live in a pretty windy area ( Livermore CA ) and the winds we encountered between Barstow CA and Las Vegas were extra strong. None the less, the other streamliners were much better in the wind and I will make some more changes to improve it. 

Extant, thanks for posting the pictures for me.  Here is the link to the Vetter website for his report and better pictures on the event : http://www.craigvetter.com/pages/2011-Streamliner/2011-vetter-streamliner-p50.html

I looked at a couple of 250 Ninjas today for my next fuel economy/ streamliner project. I should be able to break the 100mpg barrier with some gearing and aero mods.
all the best,  Dark V 

[artbone]

Where can I get a set of the Euro gears for my Vision? I've never seen any on ebay.

[Re-Vision]

Look at these:

http://www.ebay.de/itm/Yamaha-XZ-550-Getriebe-/130437518568?pt=Motorrad_Kraftradteile&hash=item1e5eae94e8#ht_2512wt_905

http://www.ebay.de/itm/Yamaha-XZ-550-Getriebe-Schaltgetriebe-Gear-box-/350412786858?pt=Motorrad_Kraftradteile&hash=item51963accaa#ht_915wt_1213

BDC

[jefferson]

Love to see you reach your goal there. Pretty neat what you are doing. What have you done to the bike other than the aero stuff? Are you running synthetics in the engine and diff? For a competition you could even run 10w40 in the diff for that extra edge. Shouldn't hurt anything as the front gears are lubed by the engine oil. Another thing I though of is gutting your speedo drive gears on the front wheel and using a gps for your speed. Lowering the bike a couple of inches would help, but your ride and handling would deteriorate pretty bad and it sounds like you ride it alot. Another trick is to reduce the tension or number of seals on the wheels, but once again maybe not a good idea for a daily ridden machine.
I think the euro gears would help out too as you have reduced the amount of power it takes to move the bike down the road with your aero improvements so the lower rpm and power the gears provide should match up nicely. Good luck.

Jeff

[The Prophet of Doom]

Look at these:

BDC

Bobby -
The Euro / US / XZ400 Gear swap is not these gears, it is done by replacing the clutch basket, and the gear off this.
Part 1 and 6 in this picture.  I can be done without splitting the crankcase which is a very good thing.
http://www.cmsnl.com/yamaha-xz550rj-1982_model8893/partslist/C-09.html

[Rick G]

I once got 49.98 mpg on a stock '82  running at 65 mph mostly on interstate 5 , in OR. The air movement of the traffic flow will have a bearing  on milage .

[Hartless]

I once got 49.98 mpg on a stock '82  running at 65 mph mostly on interstate 5 , in OR. The air movement of the traffic flow will have a bearing  on milage .

Shortage you could even get up to 65mph on I5. It's usually so congested, at least through and around portland

[artbone]

Where can I get a set of the Euro gears for my Vision? I've never seen any on ebay.

I found a set in Germany and bought them. A friend of mine is going to bring them to me when he comes to MX or the US, thus avoiding the $150 shipping.

[darkvision]

Hi, Its bee n a while since I posted on my projects. After competing in the 11/2011 Las Vegas to Barstow Vetter Fuel Economy Challenge, I thought a lot about my future participation in these real-world fuel economy contests. While I'm pleased to have improved a 40mpg bike ( 1982 Yamaha Vision 550 )into a 60mpg+ machine I have to recognize the inherent disadvantages my Vision ( 550cc, shaft-drive ) presents versus the 250cc gas bikes and the diesel bikes that have been the previous Vetter Challenge winners ( 134 mpg to 157 mpg). I decided to start looking for a used 250cc bike to modify for future fuel economy runs.
Last Decemeber after about 2 weeks of searching I found a 1999 Kawasaki Ninja 250 in good running condition for a good price and well under my project budget. It was a salvaged bike and so I had to have it inspected by the police and the engine and frame #s verified to get it titled and registered for street usage.

I adjusted the valve clearances, sparkplug gap, cleaned and re-oiled the air filter and changed the oil and filter. I topped off the tank and rode it around running errands for a few days before doing my first official mpg calculation: 65 mpg.

12/31/2011- I rode with my friend and fellow MC hypermiler, Alan Smith( Ninja 250 streamliner, 116 mpg best ) and another stock 2008 Ninja 250 as well as a Triumph 1100 and a BMW 1200. We topped off our tanks at the start of ride and refueled at the end of the ride 126.7 miles later. The ride was at a spirited pace on twisty backroads on a cold day with with about 20 freeway miles on the way back. Alan got 89.47 mpg, the 2008 ninja got 62.1 mpg and I got 72.8 mpg. I was pleased with how the bike runs and how well it handles. It was interesting to compare the 2 stock ninjas with Alan's to see how effective his modifications are. I'm pleased to already have beaten my best tankfill on my Vision 550cc ( 66.8 mpg) .

Once I had my baseline I was ready to start my modications. I began with some aerodymic modifications: larger windscreen , fully faired front fender, changed to a lower seat pad and a small strap-on tailsection. I got a best tankfill of 76 mpg.
Next I changed my front and rear sprockets from 14/45 to 15/41. I also modified the tail section so it was taller and came to a point in the back. I got a tankfill of 78 mpg and then on a longer run, I got my best tankfill of 104 mpg!

I plan on continuing to modify my bike for even greater fuel efficiency and hope to be much more competititive in future fuel economy competititons( maybe even win).

I realize many people are currently not interested in fuel economy but I believe that as the price of fuel increases this will change. I hope to help others who are interested in getting great fuel economy out of their motorcycles. I'm doing this because I think its important for all us to do our part to reduce our dependence on foreign oil and to efficiently use our limited natural resources. This is my personal contrbution in reducing the flow of American dollars to the sponsors of terrorism. I believe we all can make a positive difference. I also find it to be an interesting and fun activity.
best wishes, Darkvision

[fret not]

This has been an interesting thread and going in the right direction, higher mileage.

In my work on streamlining for the salt flats I was the beneficiary of loads of advice from some very experienced speed guys.  It's all about smoothing out the flow of the air around the vehicle and NOT creating any turbulence.  Well, it is probably impossible to totally avoid making some turbulence, but the idea is to get LAMINAR FLOW and maintain it as long as it is in contact with the vehicle.  Anytime you stick something into the flow it creates turbulence unless it is supremely designed to avoid that .   An idea for your front fender is to use a section of an air foil (wing) with the leading edge vertical, sort of like a rudder on an airplane.  Ideally a curve along the front/top would be good but the more complex the shape the more complex the remedy needs to be. 

A wing section just cut off flat on the end creates some turbulence, but if you put a flat plate across the end and allow the edges of the plate to protrude an inch or two past the profile of the wing section it helps a great deal to create and maintain laminar flow.  If you look at airplanes a lot you will see this fairly often.  Check out NACA air foils on the internet.  NACA is the predecessor of NASA, and their engineers came up with great ideas long ago and they still hold true, after all, it's physics.   

Another important thing is from the widest section of your vehicle (with you on it) the body work should converge toward the rear at no more than 10 degrees, at a little over 11 degrees a surface begins to make it's own turbulence by creating a low pressure area.  Make the tail as long as you need it but here is another thing to keep in mind, the longer the surface the more drag.  Bring the sides of the tail in about 9 or 10 degrees and cut it off where you want it stopped.  There is controversy regarding whether to cap the end or leave it open, but that one is easy enough to test and use what helps the most.  The top of your seat should also taper down no more than 10 degrees, though it probably doesn't make a great deal of difference because your helmet and shoulders create turbulence in the wind, and that turbulence creates drag on any surface it touches.  Turbulence is called "spoiled air". 

This competition thing can become addictive, and figuring out puzzles, like air flow, is just another form of competition (beating the wind).  They made wind tunnels to test theories and make improvements in designs and now the understanding of air flow has been very well developed, and much free information is available.

I mentioned only two areas for improvement but as you well know every part is effected in some manner or other.  Like we used to do for our road racers, drill holes where stuff wasn't needed, use smaller washers, drill bolts, always thinking of cutting weight any and everywhere.  No one thing probably made so much difference but all the little things would add up to a noticeable change in performance.  The more you know the better you can do.

[darkvision]

Mike, Thanks! You are spot on about laminar flow.  I'm currently working on a new tailsection that will be longer and have less abrupt angles.  I also need to change sprockets again for even taller gearing. Also my previous tail was too small to carry the 4 bags of groceries mandated by the Vetter Challenge rules. Hopefully onward and upward.

[fret not]

There probably is no end to things you can do to improve the air flow, how about replicating the surface of a golf ball all over the surface of your vehicle? :D

A longer tail is probably not the answer, as it has a degree of drag all over the surface even though it does make laminar flow.  It's a trade off to get the slipperiest form and most usable configuration.    The larger tail, as you already know, catches lots of side wind.  I suggest cutting the tail off where there is no more stuff to cover that can create turbulence.   The body work just guides the air around the bulk, if there is no more bulk, frame, lights, wheels, etc.  to create spoiled air just chop it off.  That is called a Kamm tail or Kamm back, after the inventor.

Another area where there is turbulence is just behind the tires, and not many folks bother to improve this area.  Look at the really fast rigs that run for land speed and they have had to deal with this area and lots of other areas we probably will never think of.  One fellow I talked with was concerned of the air flowing INSIDE the rig, after all, it is still air.  He has the inside of his car just as smooth as everyone else has outside.  Of course there are other reasons like ease of clean up after something blows oil or worse around the inside,  but we are not likely to be pushing 400 MPH either. 

There is a lot of room for improvement on Vetter's rig just making the surfaces smooth.  Good luck with this and above all, keep it fun.

[Rick G]

Hartless, I rode  from Stayton on 22 to Salem  and I 5 to Vancouver , then to motocross track east of there. Return trip down I 5 to Brooks. Then back roads to Sublimity . Ran out of gas at the stop sign in Sublimity  and coasted in to the Union station on one cylinder.  Yes, Portland was congested , but most of the way on I5 , I was running 65 to 70 .
Here in AZ I don't get nearly as good mileage .We have miles and miles of open space and I do love a tight throttle cable , Ask anyone who has ridden with me.

[Hartless]

Hartless, I rode  from Stayton on 22 to Salem  and I 5 to Vancouver , then to motocross track east of there. Return trip down I 5 to Brooks. Then back roads to Sublimity . Ran out of gas at the stop sign in Sublimity  and coasted in to the Union station on one cylinder.  Yes Portland was congested , but most of the way on I5  I was running 65 to 70 .
Here in AZ I don't get nearly as good mileage .We have miles and miles of open space and I do lone a tight throttle cable , Ask anyone who has ridden with me.

Next time you ride through Portland let me know! There. Are a few gas stations by my house btw!