Squid

I am thinking to design a boat moving like Squid....any supportive idea?

Abo Hamza

 

Jet propulsion, in other words.
And since it is expelling the water, it becomes... a waterjet.

 

Squid propulsion is akin to rocket propulsion in that it loses mass as it jets out the water in a single pulse. It then has to reload ready for another pulse. It is very effective for quick getaway over short distances.

It is an efficient form of propulsion if you only consider the first pulse. For steady operation its theoretical efficiency is limited to something like 50% - it has been a while since I worked out.

If you are contemplating some form of pulsating bladder drive then you need to get it so you simply apply force to the moving stream rather than having to bring the water up to boat speed first. I have contemplated something like a peristaltic pump but have never tested anything to see what can be achieved in practice. With reasonable size components I could get theoretical efficiency similar to screw type jets - around 65 to 70%

To put the 50% in perspective a well designed prop has a theoretical efficiency over 90% for easily driven boats in the 10 to 20 knot range.

Rick W

 

Sqid Boat

Jet Propulsion is not the target. I am thinking in the -Cuttlefish or Squid- side fin as a new propulsion system.

My idea is design a side fins moving in a controllable & homogeneous sinusoidal wave The generated waves at boat sides are the propulsion system.

 

Ah, it is not squid then - it's cuttlefish we're talking about. I see them as one of the most amazing animals on this planet.
About the boat - did you see this one?
http://www.youtube.com/watch?v=nS8i...-News.asp?NewsNum=815&feature=player_embedded

 

The little side fins or flaps can provide gentle manoeuvring but are not used for the high speed propulsion.

This explains how squid move:
http://www.pmmh.espci.fr/fr/gouttes/recherche/squid.html

If you want to look at effective flapping propulsion then take a look at penguins. This method of propulsion is similar to that used in the Hobie mirage drive. It achieves about half the efficiency of a good propeller.

Rick W

 

You can see the different forms of propulsion here:
http://www.youtube.com/watch?v=OBg0k9GbHiw
The flaps are used for slow economic moving but the jet is used when the squid want to move rapidly. The ink trail indicates they are in an agitated state. Some are just blurs as they rocket past. Giant squid can reportedly get to 20mph.

This clip shows more effective flapping propulsion of a penguin:
http://www.youtube.com/watch?v=uDahltR7pYg&feature=fvsr

This shows the Hobie mirage drive from under water:
http://www.youtube.com/watch?v=VljpEpjVdts

Rick W

 

What is the advantage of flapping propulsion like Mirage drive over a prop?

 

Maybe it is like the motion of a fish, where the fish is able to cancel out each opposing side ways force and turn it into very efficient fwd motion?..or just simply, because "it's there"...sounds like a fun project

 

1. It can operate in very shallow water by making very small movements. Meaning it is easily beachable.

2. Being rubber blades they can take hard hits without any damage.

3. There is a really good sales pitch that gets inexperienced users sucked in:
http://www.hobiecat.com.au/images/video/kayak/miragedrivemd.wmv

4. Not yet convinced then try this:
http://www.hobiecat.com.au/images/video/kayak/tugofwarmd.wmv

5. Not yet convinced then how about this:
http://www.hobiecat.com/kayaking/images/miragedrive/Tug-O-War_MD.wmv

Now you want one - right.

What you have to realise is that the efficiency at zero speed is that - zero. A tug-of-war has no relevance to moving through the water. How often do you want to tow a power boat with a pedal boat!!!

Rick W

 

This puts the Hobie Mirage into perspective:
http://ftlauderdaleyakfishingclub.org/hobieunplugged.html

Irrespective of this I think the Hobie Mirage is the most commercially successful pedalled craft and is making inroads into the territory held by paddled craft. You see more of these boats around every day.

Rick W

 

That is exactly my target. The boat is mainly used in shallow water as a pleasure boat or for marine structure maintenance .High speed is not essential.

As well as, another design will be as a pleasure submarine or ROV just like the attached youtube video.

More information....?


Abo Hamza

 

Daquiri

Neat little robot...bet it was a blast to design.

 

Rick,

what is the principle of the flap propulsion system?

 

if those liquified gasses called water would burn and compres it could be simple, even valveless

cant find a drawing back posted long ago of an pulsejet ob driving a pump squiting water