Proposed Twin FWE-boosted Recumbent Trike

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larry cottrill
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Re: re: Proposed Twin FWE-boosted Recumbent Trike

Post by larry cottrill » Fri Jul 29, 2005 3:04 pm

Mark wrote:Here's a link on this topic.
Mark
http://wannee.nl/hpv/abt/e-index.htm
Ha ha ... note that while he has been very analytical in most ways, he has nothing to say about the gyroscopic precession effect! Note also that in the two reasonably successful examples he shows, the adverse effect of "wrong way" precession has been minimized by making the rear wheels very small and low mass.

What's seldom realized is that turning a bike is similar to turning an airplane: you don't turn a plane by stomping on one rudder pedal, you bank it so that part of your lift becomes a centripetal force that accelerates you smoothly around a center point. Similarly, you turn a bike by banking it, so that part of your weight is converted to a centripetal force from the street into the bike at the wheel contact points. One time, I happened to see a motorcyclist make a low-speed snap turn at an intersection such that the angle of the bike centerline was no more than 45 degrees from the pavement. If he had hit a patch of grease or sand, he'd have killed himself doing it - the sidewise force of a 45-degree bank is equal to the full loaded weight of the vehicle !!! The force felt by the rider would be 1.41 Gs (not downward, but outward and downward through the bike CL toward the contact point).

Riding in an airplane making a properly balanced 60-degree(!) banked turn, the coffee in your cup will stay level with the brim, and the cup will not slide on your tray - but it will "weigh" twice as much if you pick it up to drink from it. Needless to say, an airline pilot will never make such a turn under normal circumstances, but the plane is perfectly capable of a 2G turn and much more. No bike could make such a turn on an ordinary flat surface, but could do so on a banked track, I suppose.

When my dad would take me through the midway of the Iowa State Fair, I always wanted to see the guys who ride motorcycles around the inside cylindrical surface of a giant "barrel". While the speeds are not really very high, they must be operating at 3 or 4 Gs to do that [pulling blood away from your brain toward your seat], since the cylindrical wall was only about 20 ft (6 metres) across, possibly less. Traction was not a problem, of course, because the wall was perpendicular so as to be flat "under" the bike - the ultimate "banked turn". There was a small conical "ramp" zone at the bottom of the cylinder for getting started and stopping. As a kid, I was mightily impressed by such a feat. My dad was not as easily impressed, especially when the operators invariably 'passed the hat' during the performance for some extra cash beyond the price of admission. This was for the "riders insurance fund". Ha.

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Killing Top Wheel Drag with Your Pulsejet

Post by larry cottrill » Fri Jul 29, 2005 5:37 pm

Ha ha! I just had a wonderful idea - a perfect way to utilize your LINEAR pulsejets for bike power.

I have always wondered why more hasn't been done on bikes to kill the huge drag of the wheel tops while you're rolling. Note that the tops of your wheels are moving forward through the air at TWICE the speed of the bike and rider! What a huge source of unneeded drag.

I have thought of thwarting this with a special 'top wheel fender' that would use air scoops or miniature pedal-powered blowers to channel air up from the rear over the top of the wheel, but of course little efficiency can be achieved when we're talking about something the shape of a tire and rim. But now, I have a better plan:

Instead of the Reynst-breathing engine design I showed above, go ahead and use your LINEAR engines. Instead of fitting recuperators, space an inlet out front of each engine intake and use long flexible ducts to channel the augmented blast into the rear end of special fenders around the tops of the front and rear wheels. Use specially shaped fenders, and make rims with small 'turbine buckets' at intervals of a few cm all around the sides [you'll have to go to disk brakes, I guess]. The buckets would be curved to offer good pickup of the augmented flow, and would be streamlined for traveling through outside air below the fender.

No more top wheel drag - top wheel propulsion instead!

L Cottrill

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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mike Everman » Fri Jul 29, 2005 10:07 pm

The main problem the natural inclination to design the rear wheel to be trailing the steering pivot point. It is an unstable system. Anything you come up with must want to straighten itself out after a turn.
With a trailing wheel, once you turn, the inertia of the rear end toward the outside of the turn multiplies the force you'd have to apply to straighten it out, and the more it pivots, the higher the force making it pivot and so on.

Putting the pivot directly over the axle gives you a chance but still doesn't inherently want to straighten you out when you let go of the wheel, which should be considered a mandatory feature. You might put springs with a damper to center the wheel again.

Interesting problem...
Mike
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mark » Fri Jul 29, 2005 11:55 pm

Some other thoughts I ran across.
Mark
http://www.wiskit.com/marilyn/bicycle.html
And here's a tangent I came across.
http://sidewaysbike.com/
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mark » Sat Jul 30, 2005 12:14 am

And I don't know where this topic is going but this looked quasi interesting.
Mark
http://arxiv.org/PS_cache/physics/pdf/9711/9711006.pdf
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mike Kirney » Sat Jul 30, 2005 3:32 am

A RWD bicycle would be a nightmare but a RWD tricycle would be a manageable vehicle I think, even at pulsejet induced speeds (40 -60 mph?). You could limit the angle through which the rear wheel is steered and that would help reduce spin-outs and mis-steering. You could put in some pulleys or something too to change the steering rate. I would try it but I am busy with a whole bunch of other stuff right now and just don't have time.
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mike Kirney » Sat Jul 30, 2005 3:41 am

The author in the first link mentions the negetive effect of negetive trail. It would be not be a big deal to build a RWS bike that has positive trail. I'm glad I read that page. I had not thought of that. Damn, I just realized I put RWD in the other post and not RWS. I meant RWS.
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mark » Sun Jul 31, 2005 12:00 am

Bears, boards, bicylces and stuff.
Mark
http://www.rain.org/~mkummel/stumpers/11oct02a.html
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Re: re: Proposed Twin FWE-boosted Recumbent Trike

Post by pezman » Sun Jul 31, 2005 6:44 am

Mark wrote:And I don't know where this topic is going but this looked quasi interesting.
Mark
http://arxiv.org/PS_cache/physics/pdf/9711/9711006.pdf
You post some of the most interesting references. That one was a jewel.

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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mike Everman » Sun Jul 31, 2005 7:48 am

Yeah, I liked that one too. I am fascinated by the potential of passive bipedal motion. I've got a collection of different robot walkers if anyone is interested in my posting them...
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mark » Sun Jul 31, 2005 5:28 pm

If you had a way to refresh a smallish chamber, a way to spark it at about once per second or two, you could make little feet that lifted up under the force of ejected gases, kind of a slow cycle jam jar hiss action.
Another thing that would be fun to try would be a slow cycle airplane, have as thin and light of a vessel as possible and again have some tricky way to refresh the chamber every few seconds, the little airplane could pulse along in the sky, using methanol or such, with an intermediate pulsating action, similar to a darting squid.
And as a typical jam jar volume "darts" at 20 cycles per second, you would have to trick it into refreshing with some other means than the single port breathing. Perhaps a giant flap valve on the opposite end that has a slow response, I don't know. My little platinum wires will relight methanol vapor for hours on end in a jar with a hole in the lid, as the air refreshes it glows brighter until it fires off another whoosh of gas, then it grows dim until convection brings in enough fresh air.
It all looks so easy and fun on paper. ha ha
Mark
http://chemlearn.chem.indiana.edu/demos/OscMeth.htm
http://www.chem.umn.edu/services/lectur ... monia.html
http://www.nanotechweb.org/articles/news/4/4/16/1
http://www.smartplugs.com/news/boz010900.htm
http://www.techbriefs.com/spinoff/spinoff2001/t1.html
http://www.automorrow.com/articles/smartplugs.html
Last edited by Mark on Sun Jul 31, 2005 6:04 pm, edited 3 times in total.
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mike Kirney » Sun Jul 31, 2005 5:29 pm

Here is a general explanation of bicycle physics.
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mike Everman » Tue Aug 02, 2005 1:00 am

here's a biped doing a flip.
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mark » Tue Aug 02, 2005 1:50 am

Nice flip, what is it using to hop, flip, and skip along, -- earth, air, fire, or water?
Mark
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re: Proposed Twin FWE-boosted Recumbent Trike

Post by Mark » Tue Aug 02, 2005 8:32 am

What runs the storky legs, is it pneumatic or what?
Mark
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