RTFA: http://www.youtube.com/watch?v=xHsXcHoJu-A

This is our submission for the Mythbusters video challenge

This post contains the parts list for constructing a DWFTTW vehicle, along with pictures of the finished DWFTTW product. I think the solution is for a few people to build this thing and test it out.

For some background, here’s Boing Boing’s Mark Frauenfelder:

Over a year ago on Boing Boing, I linked to this video from a guy who made a propeller-powered vehicle that he claimed could travel downwind faster than the wind. Some people think it was a hoax, and some don’t.

In Make Vol. 11, Charles Platt made a miniature model of the vehicle and came to the conclusion that there is no such thing as a wind-powered vehicle that can travel faster than the speed of the wind.

Now there’s a new video on YouTube (above) that claims it is possible to sail directly downwind faster than the wind (aka DDFTTW).

It’s obviously not a closed system, and it’s obviously not creating energy out of nothing… but that’s not the question here, either. Assuming the vehicle moves forward, it’s doing this with wind. Honestly, I don’t care how the energy gets transferred into forward motion. If it works, then it is useful. If it doesn’t work, then it just takes a few people to build this kit and it will be proved to be useless.

Well, I haven’t spent any time analyzing this, but it doesn’t seem impossible to me. I’ve been sailing dozens of times, and I’ve flown in a plane a few dozen more times. The short story of my experience is that wind, and air pressure in general, are capable of weird things. This isn’t any reason to conclude anything one way or the other, but I guess I’d like to see this one be proven incorrect before I disbelieve what my eyes are telling me. If I had a few bucks to spend, I’d like to make one of these things.

Here is the parts list, compliments of Spork (the creator of the video above):

- 4.15 Century Tail Gear Set Hawk (Tower LXMJX7)
- 6.95 Century Tail Gearbox Hawk Pro (Tower LXLKD0)
- 2.00 5×13x4 Revolution (2 front prop shaft bearings) (Avid 695-RSZ)
- 3.00 5×11x4 Revolution (2 axle bearings & 1 rear prop-shaft bearing) (Avid MR115-RSZZ)
- 21.00 Prop GWS 15×7.5 Propeller (6 for $21.00) (Tower LXHHZ1)
- 1.75 GWS 3.00″ Wheels (2 for $1.75) (Tower LXHHZ8)
- 7.00 5mm x 40″ Carbon tube for prop shaft and axle (AeroMicro)
- 4.00 4mm x 40″ Carbon tube (40″ for $4.00) (AeroMicro)
- 2 pieces at 2″ used for axle step-down
- 3.20 3mm x 40″ Carbon tube (40″ for $4.00) (AeroMicro)
- 2 pieces at 2″ used for axle step-down
- 9.99 0.08″ Music wire (2 pieces at 2″ used for axle (Tower LXWV01) step down)
@ 9.99 for 15 pieces at 36″ each
- 9.69 1.25″ of 0.063″ Music wire for rear axle (Tower LXWV00)
@ 9.69 for 15 pieces at 36″ each
- 2.00 3/8″ soft aluminum tube (24″) from plumbing dept at OSH
- 2.99 Dubro 2″ Micro Lite wheels; 2 for $2.99 (Tower: LXAZC6)
- 1.00 Nuts and bolts to hold aluminum tube to gearbox
- 1.00 HDPE Bearing block to support rear prop-shaft bearing (Tap Plastics)

Total: $79.72 Plus Tax & shipping (but you’ll have lots of leftovers)

You’ll need:
- super glue
- sand-paper
- 5mm drill bit and some standard sized bits
- exacto knife
- Metric allen wrenches

Suppliers:
www.towerhobbies.com
www.AvidRC.com
www.AeroMicro.com
OSH: Orchard Supply Hardware

The finished version should look something like the following photo gallery. These images are based on the high-quality version of the YouTube video, above.

Representing the skeptics, Charles Platt on Makezine says:

In this forum and in others hosted by Make I have explained repeatedly why a treadmill demonstration does not satisfy my original requirement. The cart should be on a level surface, experiencing a steady tailwind; it should accelerate up to the speed of the wind and should then exceed the speed of the wind. This is what Mr. Goodman claimed to have achieved. For reasons stated in my original article, I believe it is impossible.

There are a few other threads that discuss this topic, too:

James Randi Educational Foundation

Discovery Channel Community

Physics Forum

If you make this kit, please post a comment!

RTFA: http://www.tgdaily.com/content/view/33853/113

Los Angeles (CA) The inventor of the KillaCycle electric motorcycle almost killed himself during a demonstration at the Wired NextFest conference. Bill Dube, a government scientist during the day and electric bike builder at night, did a burn out in front of the Los Angeles Convention Center, but accidentally accelerated too much and crashed into a Minivan.

Freaky video. It’s totally shocking how quickly this motorcycle accelerates. I’m glad the guy was conscious and talking at the end of it, but shit. The worst part is that I can see this happening to myself - killed by my own invention… classic.

RTFA: http://www.youtube.com/watch?v=ORxRpd2RqqU&NR=1

This video was taken during an MRI scan. A scanner was installed in an old trailer without securing the grad cables!! They are hanging vertically at the back of the magnet, flapping in the magnetic breeze. This caused HUGE artifacts, both from spiking and from temporal variations in the main field and gradient fields giving the appearance of very bad eddy current compensation. Of course, eddies measured fine under the low power conditions of the eddy current compensation protcols.

Look at them fly.

RTFA: http://www.popularmechanics.com/science/extreme_ma…

Learn how to throw a boomarang, among other things.

RTFA: http://en.wikipedia.org/wiki/Space_tether#Rotovators

The word rotovator is a portmanteau derived from the words rotor and elevator. Rotovators would be momentum exchange tethers, with a retrograde motion of the tip closest to their parent body relative to the center of the tether.
Because the tips have a significant speed (typically ~1-3 km per second), it can be possible in some cases to cancel the orbital speed such that the tips are stationary at their lowest point with respect to a planetary surface or lunar body.
On bodies with reasonably low orbital speed (such as the Moon and possibly Mars), a rotovator in low orbit can actually touch the ground, thereby providing cheap surface transport as well as launching materials into cislunar space.

Even better than space elevator: Space tether!