Fin Drive and Stabilization

[swashdrive]

I will try to explain what is happening from my observation, and why a bollard pull test does not work with my fin propulsion old mate !
At static with a tow line to a load cell or scales, the fins tear a hole, aeration occurs and thrust is lost.
Once there is a certain flow over the fin, sufficient to resist this stall type situation, thrust is produced and forward acceleration increases, this grip level increases the faster the flow over the fin. You might compare the condition similar to a hydrofoil or even a boat rudder, they don't work without any flow over them !
I'm sorry but if you can't get your head around this i cannot help you, or is it you think you are helping me ?

 

[kjell]

Hydrofoils and rudder don’t produce any thrust. I am trying to help you from inventing the wheel again. It is good to trying to copy from the nature and learn how fishes are using their tails.

 

[swashdrive]

. I am trying to help you from inventing the wheel again.

Please show me were this wheel has already been invented ?

I know that for efficiency calculation "thrust" is a required field and when i apply the bollard pull in Newtons to the equation it is a very poor outcome indeed !
These figures are not the same what i'm gathering from practical tests with the fin and watt meter, they are however correct for the electric outboard.
Do you have any suggestions to better calculate efficiency ? wise Guru !

 

[kjell]

What you are trying to do is more difficult than what you think. I have been experimenting with tail propulsion for over 40 years , and I am still waiting to find the formula how to calculate the optimum tail movement/power.

 

[swashdrive]

No suggestions then, said 40yr Guru ?

Seeing that static thrust is equal to overall top-end boat speed less drag,
I am suggesting a run test were i test both units from a standing start and set to a certain power (wattage) then record what the test boat max speed gathered, time & distance covered to reach max speed.
Alternatively at a set speed, say 5 knots what is the power required in watts to maintain 5 knots !
will this work ?
Anyone else with suggestions or an equation to help explain !
regards
Craig

 

[swashdrive]

I have been experimenting with tail propulsion for over 40 years , and I am still waiting to find the formula how to calculate the optimum tail movement/power.

That one is easy, i have already done the practical test to confirm my assumptions, there is no speculating here, its 45 deg pitch 90 freq, something that may not be achievable with a Z pin (your bent shaft).



regards
Craig
Swashdrive

 

[kjell]

Craig.
Part from the years I have been experimenting with tail propulsion. I have been working as Propeller expert for 20 years, resolving propeller and engine power problems.
The power you need for a given speed is different to different types of boats. Do you know the power you need for different speed with your test boat?

 

[swashdrive]

The power you need for a given speed is different to different types of boats. Do you know the power you need for different speed with your test boat?

Again Kjell you are stating the obvious ! show me some of your wisdom !
All tests i conducted are done on the same boat, so drag is exactly the same, the different value is power, measured in watts and speed measured in knots between the two drives !

I have already conducted speed tests with both drives in this scale manned boat, the results are impressive to say the least, but i see no point if you cannot agree on a test type.

 

[kjell]

If you give me the following information and a picture of the boat out of water so I can see the hull shape, I can calculate the power needed for different speed.
Boat length in waterline. Total weight, full load with one person onboard. With these values in my program I can tell you the power you need for every speed.

 

[swashdrive]

G'day Kjell

That looks like a great program, this is what I'm talking about !
Info:
The hulls the are outriggers of a windrider sail trimaran
http://www.windrider.com/windrider16.aspx
Hulls x 2
length 3.7 metre
width 300mm
weight 40kg+ 1 person 70kg =110kg

can you calculate what theo max boat speed @ 30lbs thrust (at the shaft) in metric Watts or Kw Please !

regards
Craig

 

[kjell]

I like your 4 FIN drive. To get the best out of the Kjell-Effect, you need to make some modifications.
http://www.youtube.com/watch?v=ZKK-WXStiv4&list=ULDtD09MTUsnE

 

[frogger1225]

Eureka !

Patent pending oscillating foil

Frogging Illustrated
http://youtu.be/GRIb0EkjyTk

Frogging in the dark
http://youtu.be/gSgCFYlyCmo

Frogging in the dark (slow motion and enhanced digital lighting)
http://youtu.be/LcCzl7SzOVs