New method of traveling on water

In summary, the conversation discussed a design concept called R.P.S. (Rotating Planing Surfaces) which uses freely rotating disks to plane across the surface of the water. The lift/drag ratio and potential for improvement were questioned, and it was suggested to test the concept with a small model. The idea of powered rotation and its potential benefits were also brought up. Ultimately, the conversation highlighted the need for experimentation and consideration of different factors in order to fully understand the potential of this design.
  • #1
Colin Wilson
4
3
My question concerns what I call R.P.S. (Rotating Planing Surfaces). This version uses freely rotating disks to plane across the surface of the water somewhat similar to wheels on a car going down the road. Specifically what the lift / drag ratio might be and will it be higher than a typical planing hull at about a 5:1 ratio. My explanation of why I expect an improvement goes like this:

Since the disks rotate freely the skin friction is limited to the deflection of the boundary layer into a shallow arc from the front of the planing edge of the disk to the back of the planing edge of the disk. This results in an average differential in velocity between the planing surface of the disk and the water that is much lower than a non-rotating planing surface such as a planing hull or a lifting surface such as a hydrofoil would experience traveling at the same speed.

The following illustrations show the disks (attached hull not shown) with about 15% of the bottom surface area submerged. The attack angle of 5 degrees and the deadrise angle of 15 degrees being typical of a planing hull at speed.

Front view
Disks with WL front.jpg


Side view

Disks with WL side.jpg

Bottom view submerged area in orange
Disks with WL bottom.jpg
 
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  • #2
Take a pair of water skis and add a set of your planing disks. You will quickly find if it works, if there are any control issues, and if you need to try different geometry. This is a case where one experiment is better than 1000 opinions.
 
  • #3
A hydrofoil flies with its foils submerged so it is not affected by small surface waves. Your design appears to be a hydroplane that skims on the surface, and so is more sensitive to surface waves.

The downward weight of the vessel is still imparted to the water, so the vessel will radiate the same energy as wave pattern, circulation and wake.

You have reduced the whetted area, and reduced the differential fluid velocity, but I wonder how thick the boundary layer will need to be if it is to drive free disk rotation. Without a differential velocity the disk will not spin. Should the disk be rough, dimpled or smooth?
 
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  • #4
Welcome, Colin :cool:

Interesting idea!
I am not sure, but it seems to me that reducing the relative speed would reduce the desired lift also, which would lead to inceasing the induced drag.
 
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  • #5
Thanks for your replies. I've attached a PDF to better explain the concept and (page 4) to answer your replies. I believe I would need test tank like results to be taken seriously (test bed page 3) but I'm retired now with limited resources. I thought of maybe a crowd funding project? Any suggestions.
 

Attachments

  • RPS short ver.pdf
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  • #6
Thank you for posting that.
I like that RC boat. :cool:
 
  • #7
Interesting idea. I agree that an experiment will be the best thing to see how this works. To make a experiment that is not so expensive you can make a small model, and get a small boat that you can drive at a constant speed. Then make a rig where you can pull the model a distance off the side of the boat (so the bow wave does not affect it) and make the disks on the model able be locked. then pull the model with a line and have a fishing scale or something like that to measure the difference in drag force with the disks locked and free rotating.
 
  • #8
@Colin Wilson
You should also consider powered rotation of the disks.
 
  • #9
Baluncore said:
@Colin Wilson
You should also consider powered rotation of the disks.
He needs another form of propulsion to get up planing on the wheels anyway so i don't think adding a second mode of propulsion for after it is up on a plane is of any benefit.
 
  • #10
Stormer said:
He needs another form of propulsion to get up planing on the wheels anyway so i don't think adding a second mode of propulsion for after it is up on a plane is of any benefit.
I am not suggesting it as a form of propulsion.
It may provide more lift from the area of disk contact, by breaking or separating coanda effect.
 
  • #11
Baluncore said:
I am not suggesting it as a form of propulsion.
It may provide more lift from the area of disk contact, by breaking or separating coanda effect.
Ok. Then i misunderstood. I thought it was for boundary layer propulsion.
 

1. How does the new method of traveling on water work?

The new method of traveling on water is based on a concept called hydrofoiling, which involves using hydrofoils (wing-like structures) to lift a vessel out of the water and reduce drag. This allows the vessel to travel faster and more efficiently on the surface of the water.

2. What are the advantages of this new method compared to traditional water travel?

The main advantages of this new method of traveling on water include increased speed, improved fuel efficiency, and reduced environmental impact. By reducing drag, the vessel can travel at higher speeds with less resistance, resulting in less fuel consumption and emissions. Additionally, the use of hydrofoils causes less disturbance to marine life and reduces the risk of collisions with other vessels.

3. Are there any limitations or drawbacks to this new method?

One potential limitation of this new method is that it requires specific water conditions, such as calm and relatively flat water, in order to operate effectively. Rough or choppy waters can make hydrofoiling difficult and potentially dangerous. Additionally, the initial cost of implementing this technology may be higher compared to traditional water travel methods.

4. How does this new method impact the marine environment?

The use of hydrofoils can have a positive impact on the marine environment by reducing fuel consumption and emissions. However, it is important to carefully consider the potential impacts on marine life, particularly in sensitive areas, and take measures to minimize any negative effects.

5. Is this new method of traveling on water safe?

As with any form of transportation, safety is a top priority. While there are risks associated with any type of travel, proper training and maintenance can help mitigate these risks. Additionally, regulations and guidelines are in place to ensure the safe operation of vessels using hydrofoiling technology.

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