Add this to your electric bike

[ZOMGVTEK]

It didn't even do a burnout off the line. I always make sure to put some heat in the tire before I take off, and my 50% less effective wheel hub motor can do that with ease.

I know a 350W hub would be faster than this thing. Then you throw in the fact that its less ridiculous looking, and nearly silent, I would call this a joke.

 

[Lock]

Actually, if they put the prop up front (see cooling/bug chopping)... Made it a trike... Gave it a big comfy seat... they might be on to something

 

[alan]

Direct drive IS more efficient... fighting the air waste alot of energy

A properly designed prop can deliver well over 95% efficiency (shaft power in to air thrust out). Note that a good prop has a well designed airfoil that generates lift just like a wing. Also, a pusher rear prop can be more efficient on an airplane than a front tractor prop. I'm not saying a prop will be more efficient than a direct drive, but that you might be very surprised to see how little difference there is.

-- Alan

 

[Toorbough ULL-Zeveigh]

I'm not saying a prop will be more efficient than a direct drive, but that you might be very surprised to see how little difference there is.

WAG based on your figure, say ummm....
more than negative 5% ??

I think our community should challenge that company to a head to head competition.

with marty's rocket bike

 

[John in CR]

A properly designed prop can deliver well over 95% efficiency (shaft power in to air thrust out)....
-- Alan

Source please. What I found was 85-87% peak. That 13-15% loss compares to 0% similar losses for a direct drive hubbie. Also, having a rider in front of the prop wouldn't be anything like a nice aerodynamic form of a plane, so there would be a lot more turbulence in the flow going to the prop, which would devastate prop efficiency.

The only thing in the prop setup's favor is that it can run a small high efficiency motor like an Astro at its peak efficiency all the time, so no doubt the motor itself runs significantly more efficient than those on our bikes, but the prop losses are going to kill it. I agree that others are being overly dismissive about the claims, due to the simple fact that performance is nil. That means very little thrust is actually needed, so power consumption may not be terrible over distance. For the comparison to be in its favor it must be apples and oranges against a much higher performance ebike using the same battery.

On a bike it's definitely a fail, but it sure is a slick looking unit that I'd love to have as a gift and find some fun use for.

John

 

[amberwolf]

What I would like to see done is have one of our members who has the same motor but in a direct drive configuration do a side by side comparison.

A Kepler eboost or similar would be a nice setup to use for that, especially since it could probably install in about the same time.


FWIW, I find the appearance of the unit itself beautiful and elegant, although I do not know if it's design actually is elegant or not.

Without numbers to go on, under known conditions, it's impossible to tell if any of their comparisons or claims are accurate (or even close).

Personally, if I were going to make comparisons and claims that I'd actually tested and found true, proving my device better than some other device, I'd be posting the whole test setup and results, to brag about it.

When this doesn't happen with a product, I tend to disbelieve anything they say about it. Which means I tend to disbelieve just about *every* products' claims. :lol:

 

[VoKuS]

Maby a Turnigy CA120-70?

This looks more reasonable...

[youtube]fe9kyi5_JtM[/youtube]

Testing low-cost motor unit from Turnigy (distributed by HobbyKing in Hong-Kong, P/N CA120-70), ESC controller is a SPIN 300 Opto.
Lipo configuration is 16S2P, 8 packs of 4S (2,650mAh). Carbon prop is 24x10
no-load voltage was 67.0 volts, max-load voltage was 53.6 volts
power draw (peak) was 13.4 kW (18.2 HP), max output was 57 lbsf of static thrust. Max RPM 9,370 - temp was 20C/68F
Actual kV was around 175. (while factory rating is listed at 150kV)

This benchmark is linked to wingtip puffer testing for our 1S UL.

 

[LI-ghtcycle]

I look at it this way-

Just because a tail wind helps you on your way and is pretty efficient way to move you once your already moving, it's nothing like the power you need to actually get going in the first place.

Even Jet engine thrust powered vehicles are slow to get off the line compared to a direct mechanical connection to the wheels.

If you had enough thrust to make it worth it, you would either have way too much power to really control it effectively, or it would be so underpowered at take-off that unless you have a test track where you can just keep going around with out needing to do the typical stop and go in traffic, so either way, it's impractical.

That being said, it would still look interesting, and attract a lot of attention. Not that I would spend any money on it. :wink:

 

[LI-ghtcycle]

Here's a perfect example of what it would look like going down the road if you had enough thrust to be worth anything (and it's NOT pretty :lol: )

[youtube]ZFyvLz74X_E[/youtube]


If the prop powered bike gets rid of fart smell, this one sounds like it's powered by them!

 

[Lock]

Another data point, the sound of twin props from an ePPG pack:
http://www.youtube.com/watch?v=b9QedZlRwvc
[youtube]b9QedZlRwvc[/youtube]

 

[VoKuS]

Is it me or is this guy going up a big ass hill?

Looks to me like their is not problems with pushing you along...

Another data point, the sound of twin props from an ePPG pack:
http://www.youtube.com/watch?v=b9QedZlRwvc
[youtube]b9QedZlRwvc[/youtube]

 

[Pure]

That has to be the dumbest (most un-safe) setups I've ever seen. I can just see him taking a spill and eating one of those props into the side of his head. Not to mention with it strapped to his back like that, a sudden twist and he blows himself over. If you go through all that trouble to fabricate that harness, he really should have put it on the bike not his back.

 

[Lock]

@Pure. It's a prototype pack in development for a powered paraglider, so missing safety cages still.

@VoKus The guy's pedaling on the up hills...

Lock

 

[John in CR]

He's pedaling some, but those motors are obviously supplying the vast majority of the power. That's quite a few thousand watts being sucked out of the batteries and it wasn't much a grade. It's obviously impractical, but it does work. If idiots want to strap propellers on bikes more power to them. It accelerates evolution.

 

[dodjob]

lol M:E:G:A __ F:A:I:L
http://en.wikipedia.org/wiki/Betz'_law

 

[Pure]

@Pure. It's a prototype pack in development for a powered paraglider, so missing safety cages still.

Lock

Ah-ha! That at least makes sense. lol

 

[Eclu Lardbut]

Video http://www.youtube.com/watch?v=R6mxr-ANKIo&sns=em

It wasn't April 1st when that was made, was it?

 

[999zip999]

I'm suprise you guys are so close minded I have a propeller on the front of my ebkie and get 15% more out of my battery at 30mph. It's 6in. and on my handle bars, Oh and made from recycled plastic. Confirmed by my C.A. No pic's top secret. Please NO qyestions and No answers. JUST DROP IT.

 

[sn0wchyld]

Direct drive IS more efficient... fighting the air waste alot of energy

A properly designed prop can deliver well over 95% efficiency (shaft power in to air thrust out). Note that a good prop has a well designed airfoil that generates lift just like a wing. Also, a pusher rear prop can be more efficient on an airplane than a front tractor prop. I'm not saying a prop will be more efficient than a direct drive, but that you might be very surprised to see how little difference there is.

-- Alan

yea, they do (theoretically?) get to the mid 90%'s, but only as you approach the same speed as the air they're pushing out. and all the while, the thrust is dropping off, in an almost directly inverse relationship with efficiency. so basically, you can have good push while being about 5% efficent, or no push so long as your going about 100km'h (though at 95% efficency :lol: )

ps
im pulling the speed numbers out of my ass, it could be that you reach 95% eff. at 50km'h, though I doubt it. More likely 400km'h.

 

[Lock]

Why ebikers need this technology (nobuddy will EVer complain your ebike is "too quiet" or "too fast")
http://www.youtube.com/watch?v=GfhBH2t5Z5o
[youtube]GfhBH2t5Z5o[/youtube]

 

[parabellum]

Direct drive IS more efficient... fighting the air waste alot of energy

A properly designed prop can deliver well over 95% efficiency (shaft power in to air thrust out). Note that a good prop has a well designed airfoil that generates lift just like a wing. Also, a pusher rear prop can be more efficient on an airplane than a front tractor prop. I'm not saying a prop will be more efficient than a direct drive, but that you might be very surprised to see how little difference there is.

-- Alan

yea, they do (theoretically?) get to the mid 90%'s, but only as you approach the same speed as the air they're pushing out. and all the while, the thrust is dropping off, in an almost directly inverse relationship with efficiency. so basically, you can have good push while being about 5% efficent, or no push so long as your going about 100km'h (though at 95% efficency :lol: )

ps
im pulling the speed numbers out of my ass, it could be that you reach 95% eff. at 50km'h, though I doubt it. More likely 400km'h.

you are almost right with the numbers, I was kind of involved with model airplanes PJ engines (interested mostly in valveless). Static thrust is highly inefficient and high efficiency is only available on the setup designed speed. And those speeds/efficiency are different for any engine type, propeller setups get quite efficient wide over bicycle speeds.

 

[HoverBoarder]

I would actually like to try it just for kicks..

Having built a number of fan systems that I have put on the back of my bike, I can tell you that it is a lot of fun, but none of the ones that I have made have come anywhere close to matching the efficiency of Ebikes.

They have been fun though. It is a different feeling and experience.

I have most of the pieces for my next model ready to build, I just need to find a good place to buy some LiFePo4 or A123 batteries from, decide what voltage I want to run it at, and choose a motor controller/bike throttle.

This model looks fun, and I am very happy to see that other people have been making fan systems for their bikes as well. I like a number of things about this model, but I wouldn't have made all of the effeciency claims without more data to back it up.

Still, one of the things that I have always done is use cage protectors for the fans. It is less efficient, but it is safer.

 

[elttob]

sorry, duplicate post

 

[elttob]

I think that belongs in the same category as the PMP cranks:
http://www.classicrendezvous.com/Italy/PMP_crk_ad.htm
And with all that extra speed you're gonna get, maybe you should use an airbag helm.
http://sheldonbrown.com/airbag-helmet.html
:lol:

 

[HoverBoarder]

YT changed something in their scripting, and the pages no longer let me post comments.

Can someone else post this up there for me?

It is unfortunate that you've prevented anyone from hearing how loud it might be, with your orchestral score.

If you can provide specific test numbers for Wh/mile (or Wh/km) as well as at what speeds and slopes those are given, and for what range, without any pedalling and over multiple passes in both directions on the same stretch of path or road in a short period of time (to eliminate wind as much as possible from the results), they would be helpful in determining if your claims are true or not.


It is also unlikely that you could actually "fly your bicycle" as claimed in the video, as that propeller is far too small to give you speed needed for flight, even if you had lifting surfaces to accomplish that. So at least one claim of the video is definitely not true.

I couldn't get that whole comment in as it was more characters than allowed, the person in charge of the channel also seemed to be very opposed to any critical comments (which is very unfortunate), and so I tried to make it nice in hopes that they would respond to it.

"I have been building fan systems for the back of my bike for 4-5 years for fun, and I am happy to see a company produce a comercial ready product.

It would be nice to hear how loud the bike in operation would be. We only get a small part of the operational sound when it is starting up, but there is no sound of the bike in operation.

It would also help If you could provide specific Wh/km test numbers and note which specific ebike model you comparing it to. I look forward to more videos. Thanks"

You can see it working in the video on flat ground, and it is clear that it gives a boost of speed at least when not on a hill, but it is annoying that they would have made fantastical claims without data and claimed that they got "silence" at higher speeds.

From my last version of the fan attachment for my bike that I made, I found that there was definitely noise in the operation. However, my last version used dual 16" fans with S-shaped blades, and these were enormously less noisy than the 4 smaller ducted fans that I had first used.

I also found that I got a very noticeable boost of speed on flat grounds, a small noticeable boost of speed on small hills, and a very small boost/negligible boost of speed on larger hills. My last model used two 12V 16" 1000 CFM fans, and the next version that I was thinking about making would use four 12V 16" 3600 CFM fans. That would be about 7 times the amount of power as my last version if I decide to go with a 12V version.

It would probably be better to go with a 36V or 48V motor, but that would end up being more expensive, and this is just for fun anyways.

The Aerobicle is probably more efficient than my designs, but it would be nice to have data to back it up.

I am happy to see that there is a company that is making fan attachments for bicycles, but I am disappointed that they have made such fantastical claims without data to back it up.