Hobie Mirage Drive

[JonathanCole]

Anybody have any comments on this? It looks unbelievably efficient. Is there a reason that this can't be scaled up? Check it out at:
http://www.hobiecat.com/kayaking/index.html

[Sander Rave]

Dear Jonathan,

Can you be a little more specific? What is it you're wondering about. What do you want to scale it up for? What kind of power do you like to apply? What kind of vessel do you like to use it for?

I think this is te first thing you need to find out: how to apply force by lineair motion.
That's the first question that rises to me reading you question
Regards,

Sander

[JonathanCole]

Originally Posted by Sander Rave

Can you be a little more specific? What is it you're wondering about. What do you want to scale it up for? What kind of power do you like to apply? What kind of vessel do you like to use it for?

If you go to the web site there is a movie showing, the Mirage drive with a single operator winning a race against two champion athlete double paddlers.

This indicates to me that the Mirage drive is is able, by design, to couple horsepower much more effectively than other drives. Perhaps part of the reason relates to the fact that the Mirage drive operator is using his legs and the two man boat is using their arms. But it may also be that the unusual movement of the Mirage drive wings is an inherently better way to propel a boat through the water. It certainly seems to have other advantages as well.

Other unusual drive concepts are arising lately. This one uses a flapping hydrofoil wing to create 16 knots of speed powered by one person . Checkout the movie download on this.
http://www.newscientist.com/article.ns?id=dn7414

The use of these ideas may not be limited to human powered drives.

[mackid068]

It's probably possible to scale this up and have it powered by a small inboard motor.

[Sander Rave]

Dear Jonathan,

my first remark is the restriction the system is a one way only.
Second, it's easy to win a race legs to arms.
Third, this propulsion system operates by (almost) continous power, the guys whith their paddles don't have time to speed up because of their momentary power transmission.

I'm wondering what happens when you just put them side by side. I'm a little sceptic about this system (does it show;-) The idea is hot though, but also I'm wondering what the effectiveness is, related to other propulsion systems. delivered power <--> vessel speed.
I just love the fin thing, the leg in stead of arm force...
Regards,

Sander

[mackid068]

Legs are much stronger than arms, that's a fact, but it may be able to be powered by a motor attached to the drive mechanism.

[icetreader]

Legs are much more powerful than arms and better suited for propulsion and control of small boats but the recumbent position is problematic both biomechanically and ergonomically.
This is why out of hundreds of millions of bicycles sold worldwide each year only few are recumbent, although such bicycles have been around for many decades.

[mackid068]

Icetreader would know! His boat would be great as a testbed for the hobie mirage drive on a non-kayak.

[icetreader]

Originally Posted by mackid068

Icetreader would know! His boat would be great as a testbed for the hobie mirage drive on a non-kayak.

I really believe in leg propulsion and the Hobie drive is cool. There are some other nice drives out there that are not classic propellers, like the Pacific Tailboat "Tail" propulsion system but the challenge is to provide them with enough continuous power, and that has to be done standing, and then the problem is obviously that of stability...

Yet another "micronautical" issue...

Yoav

[yokebutt]

One of you mathematically inclined people should be easily able to elucidate what the efficiency of the system is, and how it compares to more traditional ones.

Yoke.