mabman
Member
It is going to take more like 2850mpg to win that competition. Last years winner had 2800.
Gunning for high gas mileage
- Thread starter DougPan
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S
skyl4rk
Guest
It depends how the track is set up. A lot of the mpg runs have a rolling start and they just keep rolling until it is done. So there is never a dead stop during the contest.
The questions to answer for the pilot are:
1. What is the "start motor" speed
2. How much throttle to apply
3. Which gears to use while accelerating, and what are the start and stop speeds for each gear
3. What is the "stop motor" speed (30mph)
As long as the pilot has a speedometer and knows which gear they are in, they can do the actual driving by feel. An rpm gauge is useful but not necessary.
ZnsaneRyder said:
We currently have the engine set up so that we have a centrifugal clutch and one way bearing so that we can accelerate accelerate the wheel, cut off the engine, and let the wheel coast without moving the chain. A video of our intended setup can be seen here (http://www.youtube.com/watch?v=NXJhVOFls2I&eurl)
In the video, the wheel is running with minimal load and probably spinning way fast. Therefore we need some way to gearing the engine output down (up?) so that the chain speed that the wheel "sees" is in the vicinity of a bicycle's chain speed. That way, as mabman pointed out, we have flexibility in terms of which gearing type we use.
skyl4rk said:
Hmmm. You're right. I was going off the specs provided by Nu Vinci in terms of drive train efficiency. According to "Bicycling Science" by David Wilson, chain and sprocket systems have efficiencies in the high 90's (95 -98%). I had thought about how heavy the wheel would be after sticking the nu vinci hub in, but did not realize that the car would also suffer a ~10% drive train efficiency drop.
I guess I'll be paying for the hub out of pocket and keeping it for myself then. No matter, the hub is cool enough to use for my own projects.
mabman said:
The car starts from a dead stop, so the initial acceleration to top speed would consume the most fuel for that specific pulse and glide cycle. However, the track that we will race on is notorious for strong winds, so depending on the wind gods (lateral winds please!), there may be an entire section of the track where we're just burning gas just to maintain speed.
For an ideal case of a flat track, no wind, we still need to determine the actual drag coefficient of our fairing and actual wheel friction numbers. Based on that, we think our minimum speed of the line will be the point where the losses from the wheel are equal to the losses from wind drag. And the maximum speed will be the lowest possible speed to achieve the 15mph average. Could you elaborate on the 5:1 gear box reduction? I tried a simple google search for "scooter gearbox" and didn't get too many pertinent hits.
Regarding the EFI, the benefits of EFI increase the more time the engine is running, but right now, the guys who did the project can't tell me if it's more or less fuel efficient than a properly calibrated carb.
The big problem is that the oxygen sensor that we use is meant for use in cars so it needs ~6 seconds to warm up and after that we aren't even sure if there is enough exhausted gas to properly activate the sensor. Delphi makes a mini-switching 02 sensor, but I haven't had any luck in finding someone who actually sells it.If you end up competing at the shell eco-marathon (31 days till end of registration!), maybe I'll see you there. It's a fun time, even though it's in the middle of the semester. Bring the bike too, it sounds pretty neat.
mabman
Member
I don't have any designs on that competition, it is not real world enough for me. As I said I would be happy with a fully loaded cargo bike with motor assist getting 300mpg on surface streets while able to keep up with the flow of traffic. Going to France would be ok I guess.
Here is one source for the gearbox. http://www.scooterparts4less.com/web_gas/transmission.htm It is cheap and it reverses the rotation of the crankshaft also please note. But it is the smallest and lightest gear reducer that I know of and can be gone through I think to optimize it's function.
There are some better shots of the blue bikes drivetrain here taken by the bikes maker, Jim G. http://www.outsideconnection.com/gallant/hpv/mblue/ That is the same type of gear reducer on that setup.
As you can see the bike is pretty burly and not a wind cheating machine at all. But form follows function and you can see how it does here in town at this vid: http://au.youtube.com/watch?v=GjsWm...e.com/my_videos_edit2&feature=player_embedded
This is another prototype that we are working on:
We are trying various types of off the shelf drives in order to shave down the cost of the final product but haven't hit the lottery yet there. We are focusing on load capacity at this time because it works and we had to choose between that and about 5 other concepts for monetary reasons.
Thanks for opening up this aspect to the board. It really makes one think!
Here is one source for the gearbox. http://www.scooterparts4less.com/web_gas/transmission.htm It is cheap and it reverses the rotation of the crankshaft also please note. But it is the smallest and lightest gear reducer that I know of and can be gone through I think to optimize it's function.
There are some better shots of the blue bikes drivetrain here taken by the bikes maker, Jim G. http://www.outsideconnection.com/gallant/hpv/mblue/ That is the same type of gear reducer on that setup.
As you can see the bike is pretty burly and not a wind cheating machine at all. But form follows function and you can see how it does here in town at this vid: http://au.youtube.com/watch?v=GjsWm...e.com/my_videos_edit2&feature=player_embedded
This is another prototype that we are working on:
We are trying various types of off the shelf drives in order to shave down the cost of the final product but haven't hit the lottery yet there. We are focusing on load capacity at this time because it works and we had to choose between that and about 5 other concepts for monetary reasons.
Thanks for opening up this aspect to the board. It really makes one think!
Thanks for the links. Googling "scooter transmission" yields a lot more useful results.
The vid was also pretty eye opening. I didn't realize these motorized bikes went quite so fast. I had initially wanted to make a recumbent bike frame to act as the super mileage vehicle's chassis, but welding takes a long time to learn how to do it well.
I'm curious as to how you plan to improve the load capacity. I thought that with more load, the only thing that could be done is to lower the gear ratio. And that decrease in gas consumption mileage is unavoidable. What ideas are you thinking of?
Even though it may be "wind cheating", a front fairing/windshield should greatly reduce the drag. One of super mileage vehicle's teams predecessors was the human powered vehicle teams. They were around seven or eight years ago, set a string of world records, then disappeared. Here is the design report for their 1999 tandem cycle. Even though fairing manufacture is a REALLY labor intensive project, it's pretty neat.
One other thing I was thinking of (which may not be feasible) is to distribute the weight of the cargo to both the front and the back even though that may compromise the ability to steer well. Having all that weight in the back, can't be good for the rolling resistance of the rear wheel.
The vid was also pretty eye opening. I didn't realize these motorized bikes went quite so fast. I had initially wanted to make a recumbent bike frame to act as the super mileage vehicle's chassis, but welding takes a long time to learn how to do it well.
I'm curious as to how you plan to improve the load capacity. I thought that with more load, the only thing that could be done is to lower the gear ratio. And that decrease in gas consumption mileage is unavoidable. What ideas are you thinking of?
Even though it may be "wind cheating", a front fairing/windshield should greatly reduce the drag. One of super mileage vehicle's teams predecessors was the human powered vehicle teams. They were around seven or eight years ago, set a string of world records, then disappeared. Here is the design report for their 1999 tandem cycle. Even though fairing manufacture is a REALLY labor intensive project, it's pretty neat.
One other thing I was thinking of (which may not be feasible) is to distribute the weight of the cargo to both the front and the back even though that may compromise the ability to steer well. Having all that weight in the back, can't be good for the rolling resistance of the rear wheel.
mabman
Member
A big part of our high mileage plan includes actually pedaling along with the motor. If you don't want to pedal you get worse gas mileage. Pretty simple really.
Based on our experiences riding tandem bikes over the years we are not that worried about trying to distribute the load evenly front to rear. These bikes are about the same wheel base as a tandem and so with the motor/drivetrain/fuel load weighing in around 16 kilos that leaves us with 90 kilos of capacity safely. Plus a trailer can be towed. But for us pedaling efficiency is about as high a priority as engine.
The blue bike has a 20" rear wheel which is inherently strong but weak when it comes to gearing. The current gear ratios allow for good torque off the line but the pedaling stops at 25 mph and the motor will pull it to 35 on level ground. If you can pedal at that speed you can "get on top" of the motor, similar to riding with a strong stoker on a tandem, except there are no humans that can put out the wattage a 1.5 hp engine can
The next bikes will have the ability to run larger diameter wheels up to 29"es which will help alot on top end gearing. But we are thinking that you could also run 24" diameter wheels if you need a lower COG and are shorter in stature. The bb height will be lower but for on road use that shouldn't be an issue. As you can see on the blue bike it is really high and the bike handles well enough but could be better. Especially with some fatter tires because the roads tend to be rougher than you think.
Distilling alcohol is next on the agenda after the bikes are somewhat dialed in. This will open up many possibilities for the future of this type of LSV and others.
. If you don't want to pedal you get worse gas mileage. Pretty simple really.Based on our experiences riding tandem bikes over the years we are not that worried about trying to distribute the load evenly front to rear. These bikes are about the same wheel base as a tandem and so with the motor/drivetrain/fuel load weighing in around 16 kilos that leaves us with 90 kilos of capacity safely. Plus a trailer can be towed. But for us pedaling efficiency is about as high a priority as engine.
The blue bike has a 20" rear wheel which is inherently strong but weak when it comes to gearing. The current gear ratios allow for good torque off the line but the pedaling stops at 25 mph and the motor will pull it to 35 on level ground. If you can pedal at that speed you can "get on top" of the motor, similar to riding with a strong stoker on a tandem, except there are no humans that can put out the wattage a 1.5 hp engine can
The next bikes will have the ability to run larger diameter wheels up to 29"es which will help alot on top end gearing. But we are thinking that you could also run 24" diameter wheels if you need a lower COG and are shorter in stature. The bb height will be lower but for on road use that shouldn't be an issue. As you can see on the blue bike it is really high and the bike handles well enough but could be better. Especially with some fatter tires because the roads tend to be rougher than you think.
Distilling alcohol is next on the agenda after the bikes are somewhat dialed in. This will open up many possibilities for the future of this type of LSV and others.
S
skyl4rk
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graucho
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A lot of the computer programs you use and fuel intake are over my head. But, I do under stand the EFIE portion
(due to hydrogen fuel cell installations in vehicles)
Doug, would your competiton allow any perpetual motion in your design? A few years ago I made a perpetual motion
wheel enclosed in one of my hydrogen bike-experimental builds. It would add weight, but in a good way. We machined
a perfectly balanced disk, 1"center shaft, 18" wide, 1" thick, complete with magnetic assist. (28.4 lbs)
When we had it mounted on the axle (with no load) at 35 mph it spun for over an hour before we stopped it.
Between the weight and magnetic assist It didnt want to stop. When the bike was completed I would pull in the
clutch between 25-30 mph and I could roll for a good mile.
I wanted to get 100 miles from 1/2 litre of hydrogen out of a 350cc engine. Im more of a backyard inventor and
no where close to you guys. Your goal of 2850 mi WOW! makes my head spin. I just wanted to know if these
principals could relate or help in your cause? Or maybe you have to go strictly from engine and intake mods. I wish I
was younger and lived in CA. so I could hang out and learn from you guys. Good luck on your project. graucho
(due to hydrogen fuel cell installations in vehicles)
Doug, would your competiton allow any perpetual motion in your design? A few years ago I made a perpetual motion
wheel enclosed in one of my hydrogen bike-experimental builds. It would add weight, but in a good way. We machined
a perfectly balanced disk, 1"center shaft, 18" wide, 1" thick, complete with magnetic assist. (28.4 lbs)
When we had it mounted on the axle (with no load) at 35 mph it spun for over an hour before we stopped it.
Between the weight and magnetic assist It didnt want to stop. When the bike was completed I would pull in the
clutch between 25-30 mph and I could roll for a good mile.
I wanted to get 100 miles from 1/2 litre of hydrogen out of a 350cc engine. Im more of a backyard inventor and
no where close to you guys. Your goal of 2850 mi WOW! makes my head spin. I just wanted to know if these
principals could relate or help in your cause? Or maybe you have to go strictly from engine and intake mods. I wish I
was younger and lived in CA. so I could hang out and learn from you guys. Good luck on your project. graucho
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mabman
Member
Hey Graucho, we don't see nearly enough of your work around these parts. You include little dribs and drabs but how about some content!
John-Forrest
Member
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Getting max gas mileage...
It should be obvious that most of us got into this way of getting around because we're trying to cut costs and save gas. We have reached peak oil production and are going to have to start rationing what's left while we figure out other ways to get energy. Biodiesal fuels would be ideal for these kind of bikes since we use so little compared to cars. I've heard of using algae in ocean to make fuels.
The chart is very educational and answers a question of my own. What is the best way to save gas while riding? Good maintenance is a start - if you have a loose sprocket or spark plug is coming out, you are not going to get very good gas mileage.
I shut off engine whenever I can. I shut it off at stop lights and enjoy a few minutes of quiet, then pedal to get going again. (If a car starts honking behind me, to **** with them, I'm setting an example.)
Going down steep slopes is an ideal place to start coasting. Pull in the clutch handle, lock it, and fly! You can actually go faster since engine tends to get in way. Then just as you start climbing the next hill, pedal it going again. Occasionally, I just like peace and quiet, so I pedal on flat ground and get some exercise. If you have a light bike, you can just use engine for climbing.
Going up steep slopes I really think it helps to LEAN towards hill - just like you would on a bicycle. If engine starts working hard, I also help it along by pedaling.
I recently got an 80 cc engine so I could climb hills better and keep up better downtown. (I think it's really safer to be in middle of lane, since people getting out of parking lots can't see you very well.) I thought I'd be going a lot faster, and I can get up to 35 mph but I don't like it since engine starts working too hard and vibration loosens nuts.
I discovered engine is most "comfortable" at 20 mph and there I save most gas. It's quieter and better for engine. I actually get about the same gas mileage as a 49 cc. As pointed above, even on a 150-250 cc motorcycle you get best gas mileage at 45-50 (around 70) and can get similar gas mileage to a moped riding top speed.
Also, you can take time to enjoy ride, look at the scenery, and feel a LOT safer. Who needs to go fast?
Along that line, I notice that downtown when some car impatiently swerves around me, I catch up with them at the next stop light and the first to go. I've wound up going over a couple of miles and get to my destination the same time that car did, and have less time parking, so I'm in the store before that car driver!
It should be obvious that most of us got into this way of getting around because we're trying to cut costs and save gas. We have reached peak oil production and are going to have to start rationing what's left while we figure out other ways to get energy. Biodiesal fuels would be ideal for these kind of bikes since we use so little compared to cars. I've heard of using algae in ocean to make fuels.
The chart is very educational and answers a question of my own. What is the best way to save gas while riding? Good maintenance is a start - if you have a loose sprocket or spark plug is coming out, you are not going to get very good gas mileage.
I shut off engine whenever I can. I shut it off at stop lights and enjoy a few minutes of quiet, then pedal to get going again. (If a car starts honking behind me, to **** with them, I'm setting an example.)
Going down steep slopes is an ideal place to start coasting. Pull in the clutch handle, lock it, and fly! You can actually go faster since engine tends to get in way. Then just as you start climbing the next hill, pedal it going again. Occasionally, I just like peace and quiet, so I pedal on flat ground and get some exercise. If you have a light bike, you can just use engine for climbing.
Going up steep slopes I really think it helps to LEAN towards hill - just like you would on a bicycle. If engine starts working hard, I also help it along by pedaling.
I recently got an 80 cc engine so I could climb hills better and keep up better downtown. (I think it's really safer to be in middle of lane, since people getting out of parking lots can't see you very well.) I thought I'd be going a lot faster, and I can get up to 35 mph but I don't like it since engine starts working too hard and vibration loosens nuts.
I discovered engine is most "comfortable" at 20 mph and there I save most gas. It's quieter and better for engine. I actually get about the same gas mileage as a 49 cc. As pointed above, even on a 150-250 cc motorcycle you get best gas mileage at 45-50 (around 70) and can get similar gas mileage to a moped riding top speed.
Also, you can take time to enjoy ride, look at the scenery, and feel a LOT safer. Who needs to go fast?
Along that line, I notice that downtown when some car impatiently swerves around me, I catch up with them at the next stop light and the first to go. I've wound up going over a couple of miles and get to my destination the same time that car did, and have less time parking, so I'm in the store before that car driver!
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