Am I a weirdo? Just wondering....

Discussion in 'General Questions' started by Guest, Mar 28, 2007.

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Has Bike Guy Joe lost his marbles?

  1. Yes

    90.2%
  2. No

    9.1%
  3. He had Marbles???

    0.8%
  1. Guest

    Guest Guest

    O.K., I know some of us are more adventurous than others....I've gotten that impression from reading the forums here.

    Being that I have a background in aircraft and model aircraft, I was wondering has anyone tried using a weedwacker engine and propeller to drive a bike?

    We have "experimented" here with a backpack blower and skateboard combo, but that's too cumbersome and the thrust is wrong for a bike. (the air moves too fast with not enough static thrust to do much, right around jogging speed and the fuel consumption is nothing to brag about.

    I think the neighbors get a kick out of watching the eccentric guy go up and down the road though. :???:

    I was just thinking, it wouldn't be very expensive to rig up a bike mounted 35-50cc engine with a prop from the hobby shop.

    Anyone try it before?
     

  2. woods39

    woods39 Guest

  3. Bill Snow

    Bill Snow Guest

    Yes, I have.

    Some time ago I saw a prop mounted on the back of a bicycle. Don't think it did that well as I recall, plus the danger of the spinning prop.

    I have even seen a small jet engine mounted on a bicycle.

    Bill Snow
     
  4. gone_fishin

    gone_fishin Guest

    i haven't, but i HAVE had really vivid visions of 2 chinese 70cc's on a kitty-hawk replica...

    btw-ya forgot the MBc trademark "i don't vote in polls" option :p
     
  5. Guest

    Guest Guest

    Oh yeah, keep forgetting that.

    Two of these engines would fly a model O.K. but if you recall the Wright Flyer has one big lump that use chains to power the two props....the Bros. were bike builders afterall....

    I agree that the prop thing is not a real good idea unless there are no hills in your area. I wouldn't worry about the spinning prop any more than local traffic! :grin:

    BTW, I have dial up, so trying to watch a YouTube video is a process I'll forego.
     
  6. psuggmog

    psuggmog Guest

    If you use a weedeater motor, use the full crankshart version, some of the cheaper motors use a "1/2 crank" that is ,only one side of the crank has a bearing. The way to tell is if the recoil starter is on the clutch side of the engine, it probably only has one crank main bearing. I had a couple of friends who made a hovercraft using two leafblowers for lift, using an inflatable child's wadingpool for the skirt. We pulled it in a parade with an small kid on it. I rode this bike in the parade. I could hardly stand up afterwards.
    [​IMG]
    I haven't figured where to mount the engine yet, but I figure a weedeater motor would move this one pretty well.
     
  7. Guest

    Guest Guest

    How about a "backpack" mount with a modified weedwacker cable drive to a gearbox/reduction to the wheel?
     
  8. srdavo

    srdavo Active Member

    hmmmm......cable drive......what kind of gearbox would one use?
    Is it do-able?

    8) Gearheads unite 8)
     
  9. Guest

    Guest Guest

    Wellllll....I have a Troybuilt tiller (big weedwacker type) that has a gearbox at the end iof the "stick" on the interchangable tiller drive. You can use it as a weewacker/edger/tiller ect.

    The weedwacker is pretty much 1/1 gearing, the edger I'm not sure but the tiller attatchment is definitely geared down a bit, maybe 2 or 3/1.

    It's a bigger than normal engine on the top part of it. It wasn't that expensive at Lowe's. I think the main part plus the tiller attatchment were around 200 bucks.

    Or.....just wear a backpack leaf blower, modified of course, and jet along. :D
     
  10. JFleck

    JFleck Guest

    Wow that looks like a lawsuit waiting to happen . . .

    Good Luck Though . . .
     
  11. Kaos

    Kaos Guest

    Man that looks dangerous!!! the guy stops a liitle short at the end of the clip and it looks like it comes close to hitting him in the back of the head. I saw a guy loose a couple fingers once starting a model airplane using his finger to spin the prop instead of a chicken stick so i have seen the damage they can do. with out some kind of a guard around the prop I would'nt ride that thing, it's a accident waiting to happen
     
  12. DougC

    DougC Guest

    Yea, I'd say somebody's tried it:
    http://www.thrustpac.com/

    ......although it seems to make a lot of noise for what speeds they're getting.

    You can make them work, but it's really pretty tough to make these things efficient--because what you need is a prop/fan speed that comes fairly close to the bike's speed, but no place out there makes high-efficiency fans for such speeds,,,, and all the little engines available have RPM curves that make them spin way too fast to directly drive suchy a fan, if you could even get one.
    ~
     
  13. Guest

    Guest Guest

    Those look awesome! Too much money though, I could make one for under a hundred.

    The "efficient" prop part is easy. I have all kinds of charts and ect. pertaining to how much pitch for any given speed. You could always use a reduction of some kind and make a larger, slower turning prop.
     
  14. propellor prop power seems feasible, simple, fun

    Here's a reduction drive for giant scale RC use.

    http://www.rcgroups.com:80/forums/attachment.php?attachmentid=154765]

    The builder says this is "a belt reduction unit for a 41cc "weedeater" engine that is turning a Topflite Powerpoint 24x10 prop."

    My reading about this generally suggests you get 50% more thrust with a reduction drive. The guy in the vid here;

    http://youtube.com/watch?v=RUwJRnc6uLo

    says he gets 45 mph. I get no response from him by email. I was curious about his engine, prop dia. & pitch etc.

    Playing with the numbers of my Honda GX31 & a prop I have (36' dia. & 16" pitch) leads me to a reduction of about 3.5 to 1 to get about 30 mph. It should give better acceleration & hill climbing than direct drive model plane props, designed for much higher speeds.

    It seems you could use a lightweight bike this way. You could use rear suspension easily too.

    I'd like to see it on a fully enclosed, streamlined recumbent with the engine/prop mounted higher to intercept 'cleaner' air.
     
    Last edited by a moderator: Dec 30, 2007
  15. mopedjay

    mopedjay Guest

    i built one of the backpack fans out of a leaf blower and a homemade prop out of plywood it didnt work out too well

    i would think it would be better just to have the engine driving the wheels cause even friction drive would be better than a propellor drive unless your in the water
     
  16. Tom Bartlett

    Tom Bartlett New Member

    Propeller Driven Bicycle (warning long Post)

    Back in 2000, a Zipcycle customer (I've forgotten his name) in Ohio built a propeller-powered bike, and shipped it to us for evaluation. He used a 30cc string trimmer engine with a 22" RC airplane propeller and mounted the entire rig on the back end of the bike, and included a fan guard. Unfortunately, I cannot find the photos, but we kept the bike about a month, and all the guys at the plant (including me) rode it daily. The additional weight at the extreme rear took getting used to, but overall, it worked fairly well. The initial acceleration was not great, but we simply added human power to get it started faster. Once under way, the power continued to build until about 25 mph, then it sort of peaked. The noise was greater than a normal Zipcycle, but not unduly uncomfortable. We decided not to market the bike, but overall the power train worked, it was controllable (a little more balancing was required), and (relatively) safe with the fan guard. It is almost worth building another just to re-create the looks on the faces of those you have passed. It has to be seen to be believed.
    On a side note about propeller-powered vehicles, the Lane Motor Museum in Nashville, TN has a propeller-powered tadpole trike driven by a Harley hung way up and out on front. I was there one Saturday when they took it out in the parking lot for a demonstration run. First, a very brave mechanic hand-propped the engine while the driver held the brakes. Then it was driven carefully around the parking lot (no one, absolutely no one got very close). The sight alone was worth the trip to Nashville.
    Tom Bartlett
     
  17. Sianelle

    Sianelle Guest

  18. mopedjay

    mopedjay Guest

    i was thinking i could make a hat with the weedwacker engine mounted on the back with the prop then with it on my head it would be out of the way then it would power me on anything

    and i think since the motor is attached to me and not the bike then it doesnt have to be registered right
     
  19. Sianelle

    Sianelle Guest

    [​IMG]
     
  20. Tom Bartlett

    Tom Bartlett New Member

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