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Dare
22nd March 2010, 21:10
I'm designing a spokeless bike for a class in CAD for the hell of it, but for accuracy's sake wondering if there is a bearing and drive configuration would be cheap/light/strong for a lightweight bicycle. I'ts not important in any sense it's more a test of solidworks than engineering but I like to get things right.

Think something like this but less blatantly ridiculous.
http://www.welcometohr.com/wp-content/uploads/2008/10/bike-500x357.jpg

bogan
22nd March 2010, 21:21
hmmmmmmmmm, one of the obvious challenges is to be able to get enough rigidity so it wont collapse under drive or cornering. So a wide angle between the bearings, and wide rims as well, probly 9 bearings per wheel, plus internal ring gear on the rear. Obviously wheels would be heavier than standard, but would look pretty cool!

Ocean1
22nd March 2010, 21:34
There's no rules dude. Try a recirculating ball arangement direct on the rim, wrap a synchronous drive belt outside it.

It’s one of those “everyone tries it” ideas. Cute, but some perfunctory FEA work shows it’s not structurally a great solution. Spoked wheels and chains are still around for a damn good reason.

Dare
22nd March 2010, 21:52
Obviously wheels would be heavier than standard, but would look pretty cool!

It’s one of those “everyone tries it” ideas. Cute, but some perfunctory FEA work shows it’s not structurally a great solution. Spoked wheels and chains are still around for a damn good reason.
That's pretty much the gist of it, there are only a few situations I see spokeless being a good option and this isn't one of them but as a styling exercise they are pretty fun to mess around with. Who knows, one day we might have materials or designs capable of coping with such craziness.

Thanks for the ideas :)

It has been done a few times but not with any great seriousness...
http://www.crunchgear.com/2010/02/16/nine-mechanical-engineers-build-a-spokeless-bicycle/
http://www.hyd-masti.com/2009/05/hubless-chopper-wicked-bike-without.html

Dare
26th March 2010, 23:14
Mua ha ha. :Punk:

Ocean1
27th March 2010, 09:20
What's the assembly at 12 oclock on the front wheel?

Dare
27th March 2010, 09:40
Anti dive suspension ala bmw, needs to be a bit further back for leverage to work I think, cbf drawing springs in photoshop. The assembly is now over the wheel for extra tinyness.

bogan
27th March 2010, 09:42
so how does it hold the wheels on?

Dare
27th March 2010, 09:53
Like this http://www.youtube.com/watch?v=UHoHAmrEbrk

bogan
27th March 2010, 10:02
ah yip, so not hubless (for some reason i thought you were going for hubless), just a massive diamter hub. With a lot skinnier tyre used in bicyles you should get away with less weight as the single sider bit wont be so far offset.

Urano
28th March 2010, 01:18
i've been thinkin on that solution for a while.
it came to me with three main problems:
1- with that dimensions (and use) is pretty impossible to seal the bearing properly, so if you are going to use your bike outside a showplace you'll get stuck soon, after a pair of puddles....
2- as somebody sad, the wheel is going to be a ton heavy.
3- if you use the whole wheel width, you'll have pretty hard time to brake it. and disc brakes, like it or not, are still the most efficient.

so i'd turn to think that the best middle way could be a "diameter only wheel".
the fork connects to a rod which is in the diameter of the wheel. the wheel is a light alloy frame that rolls on balls put only where the diameter rod hit the circle. the diameter rod gives rigidity to the assembly and aside you can still put a disc, like buell...


now for a completely different thing. (can i borrow your thread? ;) )
is there any engineer that is familiar with brayton?

Dare
11th June 2010, 23:36
Eeeeeef anyone is interested here is how it turned out. Slightly unfinished. Click le piccie for more uh, piccies.
<a href="http://www.novoalias.com/2010/university/solidworks-project-renders/" target="blank"><img src="http://www.novoalias.com/wp-content/uploads/2010/06/11.jpg"></img></a>

schrodingers cat
12th June 2010, 10:27
Let me know when you build it. I'd be keen to pay to watch you jump it off something and learn what spokes actually do...

bogan
12th June 2010, 10:36
looking good dude, how much are those big mutha bearing gonna cost? also have you considered how the front pivot suspension would effect stability, methinks it'd get well twitchy under brakes.

Dare
12th June 2010, 12:24
Let me know when you build it. I'd be keen to pay to watch you jump it off something and learn what spokes actually do...
Nothing a big soft shock couldn't fix http://www.youtube.com/watch?v=wzLCgooA9KQ


looking good dude, how much are those big mutha bearing gonna cost? also have you considered how the front pivot suspension would effect stability, methinks it'd get well twitchy under brakes.
Probably not more than one of those 50g wheels on those fancy carbon road bikes. Yeah rake is directly affected by shock length/that bracket on-top of the wheel, is a bit exaggerated at the mo.

bogan
12th June 2010, 12:35
Nothing a big soft shock couldn't fix http://www.youtube.com/watch?v=wzLCgooA9KQ


Probably not more than one of those 50g wheels on those fancy carbon road bikes. Yeah rake is directly affected by shock length/that bracket on-top of the wheel, is a bit exaggerated at the mo.

lol, pretty sure he was sposed to land bout a meter furthur forward!

you mean 50gram or $50grand wheels? possibly adding another link to mimic the bmw front link suspension (forget the name) would eradicate any front end 'folding'

Ocean1
12th June 2010, 16:47
Eeeeeef anyone is interested here is how it turned out. Slightly unfinished.

Nice work.

Working with solid primitives is a bit like machining everything from solid stock, can make for slightly crude and overweight structures unless you spend a lot of time refining stuff.

SW does tend to encourage that...

Check this out: http://www.rhino3d.com/

schrodingers cat
13th June 2010, 16:57
Nothing a big soft shock couldn't fix http://www.youtube.com/watch?v=wzLCgooA9KQ


Why? Does the force magically disappear?

bogan
13th June 2010, 17:26
Why? Does the force magically disappear?

read the thread from the start dude, essentially he's getting rid of spokes by using a huge hub with equally huge bearings.

schrodingers cat
13th June 2010, 17:37
read the thread from the start dude, essentially he's getting rid of spokes by using a huge hub with equally huge bearings.

Assumptions are mother of all fuck ups.

I have read from the beginning. The trouble it getting sufficient strenght into the rim - excuse me - large skinny hub. You could add a ton of material to ensure it is strong enough but that rather defeats the fundemental performance principals.

Its good to explore ideas but the wheel isn't a new design. Asthetics at the expense of performance isn't engineering, its architecture.

Don't let me rain on your parade. Carry on. As I said, I'd pay good money to watch you jump it off something

bogan
13th June 2010, 17:50
Assumptions are mother of all fuck ups.

I have read from the beginning. The trouble it getting sufficient strenght into the rim - excuse me - large skinny hub. You could add a ton of material to ensure it is strong enough but that rather defeats the fundemental performance principals.

Its good to explore ideas but the wheel isn't a new design. Asthetics at the expense of performance isn't engineering, its architecture.

Don't let me rain on your parade. Carry on. As I said, I'd pay good money to watch you jump it off something

strong enough for what? everyday use, easy, cycle equivalent of MX, not so much. And having a shock in there will soak up a lot of the impulse forces associatied with bumps etc, so i spose in that sense the shock does make some of the force dissapear.

Dare
13th June 2010, 18:02
Working with solid primitives is a bit like machining everything from solid stock, can make for slightly crude and overweight structures unless you spend a lot of time refining stuff.
I have used Rhino (albeit years ago) And it wasn't too bad, at the time it had some issues regarding what it thought constituted an 'intersect' which made complex 3d shapes fun.
That said solidworks has pretty robust lofting features should you choose to make use of them.

I was going for a more beefy oldschool jeepesque look although I wouldn't want to be the one pedaling this hunk of junk around...


Don't let me rain on your parade.

Nothing to rain on, it's finished with. I was doing it as an aesthetic exercise not a technical one, since I already know there are many reasons hub-less bikes aren't available from your local bike shop...

Real_Wolf
14th June 2010, 12:56
Its good to explore ideas but the wheel isn't a new design. Asthetics at the expense of performance isn't engineering, its architecture.


Hit it on the money. He was merely curious about what the engineers thought of it, but he was designing it because he "thought it looked cool"

Dare
14th June 2010, 16:03
Hit it on the money. He was merely curious about what the engineers thought of it, but he was designing it because he "thought it looked cool"

I'd be worried if you didn't know that about me by now :P

avgas
14th June 2010, 16:37
Mua ha ha. :Punk:
Thats pretty badass - what software you using.

In terms of bearings I would use an old school consistent roller arrangement, otherwise you might get some crazy warp out of the bearing due to the pedal and roll torque. Roller bearings are simple and have nowhere to go. But need lotsa greasin

jono035
15th June 2010, 07:40
Hit it on the money. He was merely curious about what the engineers thought of it, but he was designing it because he "thought it looked cool"

Very true, at least he knew what the correct firing order for an inline-4 engine was, though!

Real_Wolf
15th June 2010, 12:14
I'd be worried if you didn't know that about me by now :P
I do, was explaining it to other people who might not be used to your "i want to find otu everything, then ignore it and do it my way cause it looks cooler"

Very true, at least he knew what the correct firing order for an inline-4 engine was, though!
Lol, he was so adamant about it aswell

Ixion
15th June 2010, 12:27
There's at least three different firing orders used by in line four cylinder engines. DAMHIK

Dare
15th June 2010, 13:11
I do, was explaining it to other people who might not be used to your "i want to find out everything, then ignore it and do it my way cause it looks cooler"
Damn straight sonny jim.


Thats pretty badass - what software you using.
Thanks, solidworks and I'll bear that in minds, pretty sure the bearing i was thinking of wouldn't stand up to anything much without some amazing materials.


Very true, at least he knew what the correct firing order for an inline-4 engine was, though!
I thought that was Indy? Feet and arms!


There's at least three different firing orders used by in line four cylinder engines. DAMHIK
Which one is bestest?

Ixion
15th June 2010, 13:16
Damn straight sonny jim.


Thanks, solidworks and I'll bear that in minds, pretty sure the bearing i was thinking of wouldn't stand up to anything much without some amazing materials.


I thought that was Indy? Feet and arms!


Which one is bestest?

The one that fires all four together! (Actually, taht's a fourth firing order. And firing a two big twinbs would be a fifth) .

Dare
15th June 2010, 13:24
The one that fires all four together! (Actually, taht's a fourth firing order. And firing a two big twinbs would be a fifth) .

That sounds torquey. I wonder why it's not done... After all there are 4 valves to a piston these days.

bogan
15th June 2010, 13:29
That sounds torquey. I wonder why it's not done... After all there are 4 valves to a piston these days.

I'm guessing cos you would get massive pulsing on intake and exhaust flows which would create a big powerband by fucking the rest of the rev range.

Dare
15th June 2010, 13:35
I'm guessing cos you would get massive pulsing on intake and exhaust flows which would create a big powerband by fucking the rest of the rev range.

So.. Same as a normal thumper then :P

bogan
15th June 2010, 13:42
So.. Same as a normal thumper then :P

hmmm, good point, maybe not so much of a powerband then, perhaps the pulsing just rob power over the whole rev range as I can't identify anything but smooth power on the 4T bikes in below dyno

<img src="http://i27.tinypic.com/zm1lw1.jpg"]http://i27.tinypic.com/zm1lw1.jpg"/>
spot the two smokers :D

motorbyclist
15th June 2010, 13:48
all of them but the 400 yamaha and the 600 husky (IIRC)

good to see further evidence that honda engineering beats kawasaki :woohoo:

bogan
15th June 2010, 13:52
all of them but the 400 yamaha and the 600 husky (IIRC)

good to see further evidence that honda engineering beats kawasaki :woohoo:

yeh, I made it too easy leaving the names there. I would have put the KTM into the 4T just going by the curve, and fuck they rev'd the snot out of it, extra 2,500rpm after max power :shit:

avgas
15th June 2010, 14:23
all of them but the 400 yamaha and the 600 husky (IIRC)
good to see further evidence that honda engineering beats kawasaki :woohoo:
210630 I see a believer, can i get an amen......AMEN!!!!!!

Dare
15th June 2010, 14:27
I see a believer, can i get an amen......AMEN!!!!!!

Goddamn threads lose track fast around here...

bogan
15th June 2010, 14:33
Goddamn threads lose track fast around here...

:laugh: aren't you finished with it yet?

Dare
15th June 2010, 16:31
:laugh: aren't you finished with it yet?

Point. Ok how many cylinders is best?

bogan
15th June 2010, 16:50
Point. Ok how many cylinders is best?

thats easy, two! in a V configuration though

avgas
15th June 2010, 16:50
Point. Ok how many cylinders is best?
0 cylinders
2 pistons
2 valves
and the most elaborate induction system known to man.

well you are making a bicycle...........(there you go dragged it back on topic for ya)

jono035
15th June 2010, 17:58
Lol, he was so adamant about it aswell

Yeah, but he was also right, whereas you were wrong. Actually it may have been Indy, in fact I think it was a few of us.

Crank angles ignored, firing order (for cars at the very least, not 100% on inline-4 bikes) is always 1342 except for a couple of random old ford pushrod engines...

schrodingers cat
15th June 2010, 18:44
0 cylinders
2 pistons
2 valves
and the most elaborate induction system known to man.

well you are making a bicycle...........(there you go dragged it back on topic for ya)

What is the total efficiency of a bicycle - calorific input to power source (rider) to output power * efficiency of vehicle?

Dare
15th June 2010, 18:54
What is the total efficiency of a bicycle - calorific input to power source (rider) to output power * efficiency of vehicle?


A human being traveling on a bicycle at low to medium speeds of around 10-15 mph (16-24 km/h), using only the power required to walk, is the most energy-efficient means of transport generally available. Air drag, which increases roughly with the square of speed,[4] requires increasingly higher power outputs relative to speed, power increasing with the cube of speed as power equals force times velocity. A bicycle in which the rider lies in a supine position is referred to as a recumbent bicycle or, if covered in an aerodynamic fairing to achieve very low air drag, as a streamliner.


Racing bicycles have dropped handlebars, a narrow seat, and minimal accessories.
On firm, flat, ground, a 70 kg person requires about 30 watts to walk at 5 km/h. That same person on a bicycle, on the same ground, with the same power output, can average 15 km/h, so energy expenditure in terms of kcal/(kg·km) is roughly one-third as much. Generally used figures are
1.62 kJ/(km∙kg) or 0.28 kcal/(mi∙lb) for cycling,
3.78 kJ/(km∙kg) or 0.653 kcal/(mi∙lb) for walking/running,
16.96 kJ/(km∙kg) or 2.93 kcal/(mi∙lb) for swimming.
Amateur bicycle racers can typically produce 3 watts/kg for more than an hour (e.g., around 210 watts for a 70 kg rider), with top amateurs producing 5 W/kg and elite athletes achieving 6 W/kg for similar lengths of time. Elite track sprinters are able to attain an instantaneous maximum output of around 2,000 watts, or in excess of 25 W/kg; elite road cyclists may produce 1,600 to 1,700 watts as an instantaneous maximum in their burst to the finish line at the end of a five-hour long road race. Even at moderate speeds, most power is spent in overcoming aerodynamic drag, which increases with the square of speed.[4]

According to google: 100 hp = 74 569.9872 watts (74.6kw)
Compared to say, 5 w/kg * 70kg = around 350 watts or 0.47 hp

I'd say bike wins efficiency stakes, fun stakes... Not so much.

schrodingers cat
15th June 2010, 18:57
Yes, but what is the conversion rate of the person - Calories in - power out. A human generates a lot of heat.

Dare
15th June 2010, 19:02
Yes, but what is the conversion rate of the person - Calories in - power out. A human generates a lot of heat.

Wouldn't know, although I think an engine probably produces more waste heat in comparison.. Humans generally stay under 37 odd degrees.
Can anyone find out a human powerband? Rolling road with a bicycle perhaps...

jono035
15th June 2010, 19:05
From memory humans are about 1hp peak for very brief bursts (sprinters etc.) but about 0.1-0.2hp sustained.

I'm guessing that humans are probably less efficient in terms of mechanical work done divided by heat energy out. A sweating human in a breeze could probably dissipate a hell of a lot of energy as heat.

schrodingers cat
15th June 2010, 19:06
Correct - an internal combustion engine is only 25 - 30% efficient due to heat rejection.

Just curious because I'm always interested in TOTAL energy cycles. is their a doctor in the house?

I remeber reading once that peanut butter has a higher calorific value than gasoline...

Real_Wolf
15th June 2010, 22:48
Yeah, but he was also right, whereas you were wrong. Actually it may have been Indy, in fact I think it was a few of us.

Crank angles ignored, firing order (for cars at the very least, not 100% on inline-4 bikes) is always 1342 except for a couple of random old ford pushrod engines...

What? I didn't say anything about it, it was indy who was arguing for what was it, 1324? Meh, I was just talking to Janis mostly, trying to avoid any conversation which involved indy.

As for the internal combustion engine, curious fact is our most efficient energy in terms of the thermodynamic efficiency is the diesel engine, but its still quite a bit below the carnot engine

Dare
15th June 2010, 23:22
What? I didn't say anything about it, it was indy who was arguing for what was it, 1324? Meh, I was just talking to Janis mostly, trying to avoid any conversation which involved indy.

As for the internal combustion engine, curious fact is our most efficient energy in terms of the thermodynamic efficiency is the diesel engine, but its still quite a bit below the carnot engine
Ooookay.
Also, what about the stirling engine? Or the dipping head bird
Edit: Oh the carnot is hypothetical.

Slyer
15th June 2010, 23:30
1-3-4-2 bitches. Except for the new crossplane R1 which is 1-3-2-4.

jono035
16th June 2010, 08:41
What? I didn't say anything about it, it was indy who was arguing for what was it, 1324? Meh, I was just talking to Janis mostly, trying to avoid any conversation which involved indy.

As for the internal combustion engine, curious fact is our most efficient energy in terms of the thermodynamic efficiency is the diesel engine, but its still quite a bit below the carnot engine

Really? Wow, in that case my memory of the entire conversation is just backwards as hell... My apologies... No where did Indy get to...

Slyer: Interesting, wasn't aware of that, that's a weird crank angle too, to get a big-bang firing order, isn't it.

bogan
16th June 2010, 09:21
1-3-4-2 bitches. Except for the new crossplane R1 which is 1-3-2-4.

pffft, whats with all this 3s and 4s BS, the only firing order you need is 1-2 :D or even just 1!

avgas
16th June 2010, 09:38
Correct - an internal combustion engine is only 25 - 30% efficient due to heat rejection.
Just curious because I'm always interested in TOTAL energy cycles. is their a doctor in the house?
I remeber reading once that peanut butter has a higher calorific value than gasoline...
Dunno about that - but I know that Sugar is pretty damn combustible.
Sugar dust makes a good floating explosive membrane.

avgas
16th June 2010, 09:40
pffft, whats with all this 3s and 4s BS, the only firing order you need is 1-2 :D or even just 1!
Or like my old Chevanne
1342,34,1,3,2,1234,1324,1342,1342,142,2,3,1....... .............................

bogan
16th June 2010, 09:56
Or like my old Chevanne
1342,34,1,3,2,1234,1324,1342,1342,142,2,3,1....... .............................

:lol: bet that had a mean cool exhaust note, kinda like them harleys even?

Real_Wolf
16th June 2010, 13:13
lol, thats an awesome firing order.

Lol Dare, yes, the carnot engine is the hypothetical engine where the maximum possible efficiency is observed, due to no process being fully thermodynamically reversible it can not be achieved.

jono035
16th June 2010, 13:37
http://en.wikipedia.org/wiki/Scuderi_Engine

Just remembered this from a lecture given a few months ago by one of the Audi high-ups.

Interesting idea really, one of the key aspects that the guy mentioned was that it allows much higher combustion chamber temperatures which are key to efficiency.

Edit: Also a few other neat parts like allowing the fuel to be sprayed directly into the hot pre-compressed charge air without having the hassle of injecting into the combustion chamber. This has some pretty big advantages for predictable fuel-air mixing etc. Their main selling point seems to be the after-top-dead-centre firing...

bogan
16th June 2010, 13:49
http://en.wikipedia.org/wiki/Scuderi_Engine

Just remembered this from a lecture given a few months ago by one of the Audi high-ups.

Interesting idea really, one of the key aspects was allowing much higher combustion chamber temperatures which are key to efficiency.

hmmm, I'm guessing the intake valve on the combustion cylinder is still partially open at TDC to give a high enough compression ratio? I'm kinda struggling to see any benifits over the conventional cycle tbh.

Some of my personal favourites are the steam based 6 stroke (http://en.wikipedia.org/wiki/Six-stroke_engine) and the supercharged two stroke (only diesel so far as can't direct inject petrol yet) (http://en.wikipedia.org/wiki/Two-stroke_diesel_engine)

jono035
16th June 2010, 14:05
hmmm, I'm guessing the intake valve on the combustion cylinder is still partially open at TDC to give a high enough compression ratio? I'm kinda struggling to see any benifits over the conventional cycle tbh.

Some of my personal favourites are the steam based 6 stroke (http://en.wikipedia.org/wiki/Six-stroke_engine) and the supercharged two stroke (only diesel so far as can't direct inject petrol yet) (http://en.wikipedia.org/wiki/Two-stroke_diesel_engine)

It's a little difficult to visualise because it's so similar to a standard otto cycle engine, but behaves so differently. One of the features they mention is that by separately compressing the input charge air, they can cool it before it enters the combustion chamber, allowing the equivalent of higher compresion.

In the combustion chamber, the intake valve only opens at TDC, at which point the pressure in the crossover chamber (where the compressed air from the other cylinder ends up) is at the compression pressure. The pressure differential means that after a short period the combustion chamber has enough charge in it to start a power stroke so the intake valve closes and the mixture is ignited.

So basically the stroke is TDC-intake-ignition-power-BDC-exhaust-TDC.

It's a neat idea, and I like it because of the novelty but it certainly seems to have a few design challenges associated with it.

One of the main advantages they mention is that basically it can be considered as a separate compressor and 'combustor', allowing a large air reservoir to be placed between them. This means that a certain amount of energy can be regenerated while braking by disabling the combustor cylinder (by simply leaving both valves closed, similar to existing cylinder-disabling tech) and using the compressor to raise the pressure within an air tank. This energy can then be 'retrieved' by disabling the compressor and only running the combustor. That's the only way that I've heard of to do regenerative braking entirely within a petrol engine (i.e. doesn't require an electric drivetrain). There was a mention of it being a possibility with good enough valve timing control to even use an air tank to run the thing entirely on the compressed air without any combustion at all for a short period of time.

I've seen that 6 stroke thing mentioned before, very interesting idea.

Slyer
16th June 2010, 14:14
So have we answered the question? Yes, there are mechanical engineers in the haus.

bogan
16th June 2010, 14:17
hmmmm, the intake valve will be open so briefly as to become a design/rpm constraint I reckon. Also storing energy in a tank also means storing petrol vapor in there as well, which would condense out wouldn't it? The supercharged two stroke direct injection design does all this without the valve constraints, or compressed vapor issues. And with orbit's apparent breakthrough allowing direct injection of petrol (albeit with a bunch of air) perhaps the design could be made to work with petrol.

jono035
16th June 2010, 14:34
hmmmm, the intake valve will be open so briefly as to become a design/rpm constraint I reckon. Also storing energy in a tank also means storing petrol vapor in there as well, which would condense out wouldn't it? The supercharged two stroke direct injection design does all this without the valve constraints, or compressed vapor issues. And with orbit's apparent breakthrough allowing direct injection of petrol (albeit with a bunch of air) perhaps the design could be made to work with petrol.

Could very well become a design/rpm constraint, although it will be an ultimate-power-output constraint, not necessarily an efficiency constraint which is what they're shooting for primarily. I believe they are injecting into the air-stream right before the valve, using the swirl over the valves to ensure an even charge density.

It's not that dissimilar to the idea of a supercharged 2-stroke. I'm sure there are a lot of advantages that are shared between them.

Also, none of this is an all-or-nothing type approach. There may be merits to both and specific advantages/disadvantages that make each one more or less useful for any given example. Both could end up being useful for entirely different purposes.

The ability to use the compressed air as a block of regenerative storage is an interesting one though. Could also possibly be used to provide for other systems such as power steering etc. if the intake compressor was sized to have a longer stroke than the combustor or something.

jono035
16th June 2010, 14:38
So have we answered the question? Yes, there are mechanical engineers in the haus.

Don't look at me, I'm an electrical kinda guy, the mechanics quickly leaves me baffled.

bogan
16th June 2010, 14:46
The ability to use the compressed air as a block of regenerative storage is an interesting one though. Could also possibly be used to provide for other systems such as power steering etc. if the intake compressor was sized to have a longer stroke than the combustor or something.

have you seen the modded ducati which uses the rear cylinder to supercharger the front one? ended up making slightly more power than stock I think, it uses a charge tank for engine braking I think, which is a fantastic idea as you can run on tank air for brief acceleration bursts without any hp losses associated with running a supercharger.

bogan
16th June 2010, 14:47
Don't look at me, I'm an electrical kinda guy, the mechanics quickly leaves me baffled.

I'm a mechatronics major, means everything only leaves me slighty baffled :confused:

jono035
16th June 2010, 14:51
have you seen the modded ducati which uses the rear cylinder to supercharger the front one? ended up making slightly more power than stock I think, it uses a charge tank for engine braking I think, which is a fantastic idea as you can run on tank air for brief acceleration bursts without any hp losses associated with running a supercharger.

No, I'll have to take a look around for that, that's very interesting...

bogan
16th June 2010, 14:53
http://thekneeslider.com/archives/2009/01/12/ducati-v-one-twin-to-supercharged-single-conversion/ there ya go, the ducati v-one

schrodingers cat
16th June 2010, 17:17
Don't look at me, I'm an electrical kinda guy, the mechanics quickly leaves me baffled.

electrics is all just pipes and smoke. If you kink the pipes the smoke comes out and it doesn't go.

Thats how I understand 'white-mans magic' anyhoo

motorbyclist
17th June 2010, 16:01
thats easy, two! in a V configuration though

nah, v-four ftw



Slyer: Interesting, wasn't aware of that, that's a weird crank angle too, to get a big-bang firing order, isn't it.

it's to get a v4 firing order with appropriate exhaust note ;)


Correct - an internal combustion engine is only 25 - 30% efficient due to heat rejection.
.

IIRC the human digestive system was marginally more efficient than an ideal carnot cycle (which was only a maximum of 35% or something given a typical four stroke)



So have we answered the question? Yes, there are mechanical engineers in the haus.

actually, we're all mechatronics or electrical or not engineers at all..... of course it's pretty hard to find automotive engineers in this country at all and they're all working on bio-diesel or similar as that's all there's funding for at the moment

the mechanical guys are all doing structural stuff, manufacturing (not the cool part that the 'tronics guys do) or HVAC.

HVAC. Heating, ventilation and air conditioning. woo hoo :rolleyes:


have you seen the modded ducati which uses the rear cylinder to supercharger the front one? ended up making slightly more power than stock I think, it uses a charge tank for engine braking I think, which is a fantastic idea as you can run on tank air for brief acceleration bursts without any hp losses associated with running a supercharger.

long story short, they went from 84hp all the time, to around 40hp most the time (ie around most IL4 250 bikes) and 100hp for ten seconds.

begin rant

i'm a bit annoyed about that:

for one, that motor was pretty lame anyway; I'd be interested to see what it does given some basic performance work without the supercharger (ok, maybe major work considering it has only 2 valves per cylinder). you'll note their new claimed power output has a redline 30% higher than the stock arrangement, without mentioning modification to the belt driven desmo two valve. Surely they should have dyno'd the stock motor tuned to run at that speed too? Otherwise how much power was the charger and how much was due to the revs?

next, heat; it's air cooled with a tiiiny oil cooler, and the working cylinder has had it's power output more than doubled. how do they deal with the extra heat? ie how long can this run under boost?

volumetric efficiency; the dragging cylinder won't help without major work. It physically can't as its pumping the same air the firing cylinder would suck anyway with extra valves to hinder the flow. The only way this would work is with in a 2 stroke arrangement with significant overbore, which required reed valves or re-engineering the cams and rockers to run at double speed.

the fine print; they run an air tank under the seat at 40bar to give a ten second boost. The "supercharger" is only really there to pump up the tank to give boost. ie, their power claim will be with the boost on as high as they dare to run it. safety issues aside, there ARE pumping losses associated with that supercharger simply to pump that presssure, plus they lost a cylinder to drive it!

so 95% of the time they're pulling less than half the stock motor power, except for brief, intermittent bursts where the motor is well past it's limits and will probably seize given any longer boost time. and the more often you want the boost the harder you're going to have to pump the compressor, which means less power the rest of the time

they may as well have removed the dead cylinder entirely and fitted a normal, purpose built supercharger in it's place. Maybe even re-worked the ducati electrics with a heavy duty charging system and run an electric super instead? Heck, why not fit an appropriately sized turbo?
If you want to avoid supercharger losses when wyou don't want the power, just use a clutch!

/rant

jono035
17th June 2010, 17:55
nah, v-four ftw



it's to get a v4 firing order with appropriate exhaust note ;)



IIRC the human digestive system was marginally more efficient than an ideal carnot cycle (which was only a maximum of 35% or something given a typical four stroke)




actually, we're all mechatronics or electrical or not engineers at all..... of course it's pretty hard to find automotive engineers in this country at all and they're all working on bio-diesel or similar as that's all there's funding for at the moment

the mechanical guys are all doing structural stuff, manufacturing (not the cool part that the 'tronics guys do) or HVAC.

HVAC. Heating, ventilation and air conditioning. woo hoo :rolleyes:



long story short, they went from 84hp all the time, to around 40hp most the time (ie around most IL4 250 bikes) and 100hp for ten seconds.

begin rant

i'm a bit annoyed about that:

for one, that motor was pretty lame anyway; I'd be interested to see what it does given some basic performance work without the supercharger (ok, maybe major work considering it has only 2 valves per cylinder). you'll note their new claimed power output has a redline 30% higher than the stock arrangement, without mentioning modification to the belt driven desmo two valve. Surely they should have dyno'd the stock motor tuned to run at that speed too? Otherwise how much power was the charger and how much was due to the revs?

next, heat; it's air cooled with a tiiiny oil cooler, and the working cylinder has had it's power output more than doubled. how do they deal with the extra heat? ie how long can this run under boost?

volumetric efficiency; the dragging cylinder won't help without major work. It physically can't as its pumping the same air the firing cylinder would suck anyway with extra valves to hinder the flow. The only way this would work is with in a 2 stroke arrangement with significant overbore, which required reed valves or re-engineering the cams and rockers to run at double speed.

the fine print; they run an air tank under the seat at 40bar to give a ten second boost. The "supercharger" is only really there to pump up the tank to give boost. ie, their power claim will be with the boost on as high as they dare to run it. safety issues aside, there ARE pumping losses associated with that supercharger simply to pump that presssure, plus they lost a cylinder to drive it!

so 95% of the time they're pulling less than half the stock motor power, except for brief, intermittent bursts where the motor is well past it's limits and will probably seize given any longer boost time. and the more often you want the boost the harder you're going to have to pump the compressor, which means less power the rest of the time

they may as well have removed the dead cylinder entirely and fitted a normal, purpose built supercharger in it's place. Maybe even re-worked the ducati electrics with a heavy duty charging system and run an electric super instead? Heck, why not fit an appropriately sized turbo?
If you want to avoid supercharger losses when wyou don't want the power, just use a clutch!

/rant

Well in terms of 'pumping losses', a normal engine has those anyway, and if everything were perfect, the rear cylinder pumping full capacity every cycle and then that being solely fed into the front cylinder would result in the same total airflow, with the same total 'pumping loss' with the same total output power because the same total petrol is being burned.

Of course, it won't work out like that but it doesn't seem all that far off.

I certainly think that they'd pick up the extra 16 HP with tweaking to the original engine, but I like the idea nonetheless.

Also, 40hp is enough to keep you moving at 100km/hr so with some modification to be able to entirely shut off the pump once the tank is full, it could end up having similar performance (boosted single cylinder for accel, N/A single cylinder for cruising) to the original bike under cruising conditions.

Assymetrically sized cylinders could be an interesting one too.

All in all, an interesting exercise but I would have expected an engineer student to be a bit more in tune with people doing things like this 'because they can'.

bogan
17th June 2010, 18:12
All in all, an interesting exercise but I would have expected an engineer student to be a bit more in tune with people doing things like this 'because they can'.

indeed, though the article was pretty biased by the sounds of it, pity that.

also worth adding that the stock wouldn't have made more power at higher revs as without any forced induction it wouldn't get a significant amount of air, thats why the modded engine runs higher rpm.

Still a cool idea to use existing equipment to supercharge the engine, though when it boils down to it, its a supercharged engine with half the cc, can't expect too much.

schrodingers cat
17th June 2010, 18:52
note ;)

IIRC the human digestive system was marginally more efficient than an ideal carnot cycle (which was only a maximum of 35% or something given a typical four stroke)




Ewwwwwwwww interesting.

So here's another question - whilst food is a 'renewable resourse' by the time it gets on our plate it has had a good deal of carbon expended on it (Production, processing, storage, distribution, preparation)

Which energy source is more efficient in a total sense - 100 000 calories of diesel or 100 000 calories of food?

Maybe the lentil eating (methane farting) treddly greenies should shut the fuck up about how great the bicycle is. After all - the majority of bicycles aren't carved from wood are they? There is a whole industry supporting bicycles - just like cars and motorcycles.
It is a product of the industrial revolution with all its inherant problems.

jono035
17th June 2010, 19:08
I'm not sure what's worse, incoherent ranting greenies or incoherent anti-greenie ranting...

bogan
17th June 2010, 19:12
I'm not sure what's worse, incoherent ranting greenies or incoherent anti-greenie ranting...

well i always go for both angles, incoherently ranting at greenies and the anit-greenies, what really gets my goat is vegetarians who drive suvs :angry: or people who use solar powered bbqs, you can't stand round them having a beer and a good yard, too fucking shiny init.

schrodingers cat
17th June 2010, 19:22
I'm not sure what's worse, incoherent ranting greenies or incoherent anti-greenie ranting...

There is a very real question in here darling. Care to try to exercise your brain?

bogan
17th June 2010, 19:27
There is a very real question in here darling. Care to try to exercise your brain?

bit of an open ended question isn't it, efficiency as in total work in / total work out doesn't really apply as your food has to be grown before it is 'picked', whereas oil is out there ripe for the 'picking' as is

bottom line is its humans that are overusing all the resources, doesnt matter how efficient your shit is, too many is still too many.

motorbyclist
17th June 2010, 19:47
Well in terms of 'pumping losses', a normal engine has those anyway, and if everything were perfect, the rear cylinder pumping full capacity every cycle and then that being solely fed into the front cylinder would result in the same total airflow, with the same total 'pumping loss' with the same total output power because the same total petrol is being burned.

......

All in all, an interesting exercise but I would have expected an engineer student to be a bit more in tune with people doing things like this 'because they can'.

a normal engine isn't fighting 40bar except for when it's producing power. their one goes from two cylinders pumping and producing power, to (effectively) three with two fighting a very high head, being driven by only one!

without the reservior it's just an exercise in reducing efficiency

it would be an interesting project if it made the bike better.

in my view, it didn't, and they're going to be ripping off the 40 customers who buy these bikes....

maybe i just don't like ducati motors, if they did it to my favourite V4 and did a fair power comparison i'd still have a go at them for ruining a perfectly good V4....



bottom line is its humans that are overusing all the resources, doesnt matter how efficient your shit is, too many is still too many.

or rather too much is too much; americans/australians use far more per capita than other developed nations (we aren't that good ourselves, mind you).

biggest irony in energy efficiency is that it results in higher overall energy consumption. it's kinda like how having more shelves just means you find more stuff to fill it - using less energy just gives you more money to spend on other ways to consume energy or use the more efficient device in a more wasteful way.

ie not turning energy efficient bulbs off because "it still works out cheaper" and using the money you saved to go do a coro loop instead ;)

bogan
17th June 2010, 19:55
ie not turning energy efficient bulbs off because "it still works out cheaper" and using the money you saved to go do a coro loop instead ;)

where you have to run bout 80w of lighting anyway, negating any energy gains befor you even take the kinetics into account! though i did find out recently that you can just run running lights instead of a headlight under the new law :yes:

schrodingers cat
17th June 2010, 20:14
Actually it is all a solar cycle. Oil also is biomass that was grown and is in effect 'stored' solar energy.

My point is that methods of transportation seldomn get an apples/apples comparison

Your closing staement is well intentioned but a generalisation. Poor position for as engineer to take when trying to strike the death blow

bogan
17th June 2010, 20:27
Actually it is all a solar cycle. Oil also is biomass that was grown and is in effect 'stored' solar energy.

My point is that methods of transportation seldomn get an apples/apples comparison

Your closing staement is well intentioned but a generalisation. Poor position for as engineer to take when trying to strike the death blow

my point was that its too hard to do a proper comparison, you asked the question so kinda renders your point confusing :confused: i'm also confused by the 'death blow' thing, I am an engineer, but an unbiased one who calls it how he sees it.

Unless of course you weren't refering to my post in which case, or even if you were, quote button is good :yes:

schrodingers cat
17th June 2010, 20:40
I realise that because there are so many variables the question is difficult.

Have you ever wondered tho? Or is all human energy considered 'free'

jono035
17th June 2010, 20:42
Maybe the lentil eating (methane farting) treddly greenies should shut the fuck up about how great the bicycle is. After all - the majority of bicycles aren't carved from wood are they? There is a whole industry supporting bicycles - just like cars and motorcycles.
It is a product of the industrial revolution with all its inherant problems.

I think you guys are just feeding a troll, to be honest. I'm staying out of this, I don't need the blood-pressure-spike.

bogan
17th June 2010, 21:03
I realise that because there are so many variables the question is difficult.

Have you ever wondered tho? Or is all human energy considered 'free'

its considered renewable, which is important for the greenies. And more interesting than trying to figure out the relative efficiencies is considering the implications ;)


I think you guys are just feeding a troll, to be honest. I'm staying out of this, I don't need the blood-pressure-spike.

meh, i need a diversion from trying to get my link geometry to work, tis not going well :no:

jono035
17th June 2010, 21:14
meh, i need a diversion from trying to get my link geometry to work, tis not going well :no:

Fair enough, I find my brain works better when I take some time away from banging my head against brick walls, though ;)

bogan
17th June 2010, 21:28
Fair enough, I find my brain works better when I take some time away from banging my head against brick walls, though ;)

something must have worked, got it sorted now i think,hope it works in practice though :yes:

jono035
17th June 2010, 21:43
something must have worked, got it sorted now i think,hope it works in practice though :yes:

Hahaha good stuff...

motorbyclist
17th June 2010, 23:34
Fair enough, I find my brain works better when I take some time away from banging my head against brick walls, though ;)

and that's why i go through so much coffee :D

avgas
18th June 2010, 09:48
Which energy source is more efficient in a total sense - 100 000 calories of diesel or 100 000 calories of food?
Very simple actually - if you burn 100KCal of Diesel, you receive it all in 1 burst. Where if you eat it all, you use some and store the rest.
Very smart TDi does this to an extent, it has stored diesel, and only uses what it can depending on what it knows.
So does this make one better than the other - nope.
Efficiency is a wonderful thing - its absolutely fucking useless without a system.
Otherwise everything is 100% efficient as you should never lose energy, it just changes.

Real_Wolf
18th June 2010, 10:16
Very simple actually - if you burn 100KCal of Diesel, you receive it all in 1 burst. Where if you eat it all, you use some and store the rest.
Very smart TDi does this to an extent, it has stored diesel, and only uses what it can depending on what it knows.
So does this make one better than the other - nope.
Efficiency is a wonderful thing - its absolutely fucking useless without a system.
Otherwise everything is 100% efficient as you should never lose energy, it just changes.

Gotta just say, nothing is 100% efficient because of entropy. But your right that efficiency means nothing unless the efficiency applies to a system. After all, your heater is averagely efficient in terms of electrical to heat, but how efficient is it in heating up a room?

bogan
18th June 2010, 10:24
Gotta just say, nothing is 100% efficient because of entropy. But your right that efficiency means nothing unless the efficiency applies to a system.

oh i dunno, my entropy generator seems to be working pretty well :whistle:

jono035
18th June 2010, 10:55
Gotta just say, nothing is 100% efficient because of entropy. But your right that efficiency means nothing unless the efficiency applies to a system. After all, your heater is averagely efficient in terms of electrical to heat, but how efficient is it in heating up a room?

That's a perfect example because in actual fact it isn't even the efficiency of heating the room, it's the efficiency of making the people inside the room feel warm, which is an entirely different kettle of fish altogether!

Real_Wolf
18th June 2010, 11:25
That's a perfect example because in actual fact it isn't even the efficiency of heating the room, it's the efficiency of making the people inside the room feel warm, which is an entirely different kettle of fish altogether!

Yeah, I'm really suprised, because usually my analogies are terrible

jono035
18th June 2010, 12:57
Yeah, I'm really suprised, because usually my analogies are terrible

Well it was a good example to begin with, but the fact that you'd singled out the wrong outcome of that same discussion made it a better one. Success with partial extra credit.

schrodingers cat
18th June 2010, 18:43
its considered renewable, which is important for the greenies. And more interesting than trying to figure out the relative efficiencies is considering the implications ;)




Ok then, ignore the efficiency question. Implications are interesting. Biofuel for instance. It really isn't terribly 'green' is it? That's why we have a responsibility to ask hard questions.

As a point of interest, the last year of A1GP, a big fuss was made of them running BioFuel and having a green conscience. It was E85 made from sugerbeet - no problems there then - until they AIRFREIGHTED the meeting supplies to New Zealand.

Real_Wolf
18th June 2010, 20:27
tbh shrodinger, most of us here don't particularily care, either way.

The greens do have some good points, we are polluting the environment. The anti-greens also have some good points, the things we're doing to save it aren't helping. The ones on the fence also have a good point, politicians will always try to look like their doing something important

bogan
18th June 2010, 20:39
tbh shrodinger, most of us here don't particularily care, either way.

The greens do have some good points, we are polluting the environment. The anti-greens also have some good points, the things we're doing to save it aren't helping. The ones on the fence also have a good point, politicians will always try to look like their doing something important

so in the end it doesn't matter which horse you back, you can still look down on everyone from atop it :yes: if you're into that sorta thing that is.

Real_Wolf
18th June 2010, 21:23
lol, bogan, if we're taking an 'in the end it doesn't matter', we might as well not be energy efficient, as entropy will catch up to us anyway. We already know what will 'end' the universe.

bogan
18th June 2010, 21:48
lol, bogan, if we're taking an 'in the end it doesn't matter', we might as well not be energy efficient, as entropy will catch up to us anyway. We already know what will 'end' the universe.

perhaps i should have said at the moment it doesnt matter, thats more what i meant, anyway the whole end of universe is ages away, we will have found another one by then.

motorbyclist
20th June 2010, 01:20
tbh shrodinger, most of us here don't particularily care, either way.

The greens do have some good points, we are polluting the environment. The anti-greens also have some good points, the things we're doing to save it aren't helping. The ones on the fence also have a good point, politicians will always try to look like their doing something important
dude i think someone else has been using your account

Real_Wolf
20th June 2010, 01:43
why, cause i made a good point?

Slyer
20th June 2010, 02:24
I believe that was the jab, yes.

Dare
20th June 2010, 14:46
lol, bogan, if we're taking an 'in the end it doesn't matter', we might as well not be energy efficient, as entropy will catch up to us anyway. We already know what will 'end' the universe.

The big crunch?

jono035
20th June 2010, 15:35
The big crunch?

I think the latest idea is that the universe will keep expanding and will reach an equillibrium in its lowest energy state...

bogan
20th June 2010, 16:14
I think the latest idea is that the universe will keep expanding and will reach an equillibrium in its lowest energy state...

fuck, we must be running out of energy cos those bastards in suv's are using all the dinosaur juice; shun them!

avgas
14th August 2010, 11:08
thought you all might find this interesting

http://www.yankodesign.com/2010/08/13/no-spokes-cycle/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+yankodesign+%28Yanko+Design+-+Form+Beyond+Function%29

Squiggles
14th August 2010, 15:45
thought you all might find this interesting

http://www.yankodesign.com/2010/08/13/no-spokes-cycle/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+yankodesign+%28Yanko+Design+-+Form+Beyond+Function%29

Be fooken easy to go over the bars no?

Slyer
14th August 2010, 16:26
It looks pretty heavy on the rear so that's probably not as much of a consideration.
I don't get why the wheels have to be such different sizes though.

PirateJafa
15th August 2010, 02:51
Because they over-thought the rear then had to tack the front on as best they could?

Real_Wolf
15th August 2010, 08:57
"The small front wheel saves space and enhances maneuverability."

Sure... cause small wheels are best

motorbyclist
15th August 2010, 23:18
saves space? the front wheel makes for a horrible ride and lethal potholes perhaps....... low pivot vs high weight means it probably would do mean faceplants