Air bubble lubrication successful trials

I would be hesitant to accept that the engine produces this much hp in say a real rubber tire to asphalt traction method. Generally, you cannot get a coefficient of friction of more than one in a dry smooth interface between surfaces. BUT that being said, most 1/4 milers do achieve a higher CF but just barely, due to a couple of factors. 1) adhesion of the rubber to asphalt due to heat, ie stickiness and the slight mechanical friction gain due to the irregularities of surface.

So there is pretty much an upper limit of what traction ie CF that you can produce, and in order to create more forward thrust/force you need more weight which then increases the need for more thrust for F=MA

To be clear, I do not doubt that the motor CAN produce 1,000 hp, but the amount of hp that the engine needs to produce is determined by the friction that the vehicle can produce between the tires and the asphalt.

 

Thanks, Barry.

My guess is the Tesla has quite a sustainable range 200 Mi? at highway speeds which are about 70 mph oh, may only draw about 50 horsepower to do that cruising. But it is capable of over 1000 horsepower, and not sustainable at that level. Maybe that's a similar situation to getting a boat up on plane, except that after getting up on plane the horsepower level never drops back down very much from the peak required, so most likely it is not sustainable, would be my guess.

 

Hi Jake
Listed below is the design and performance data of my boat Turtle which you witnessed at the last CCC, The air injection system worked great but the boat design failed and was very slow.
Race 1 length 300 m
No air was used to meet the race rules on voltage limits.
Max speed 3.6 mph
Due to the boats high drag the motor/ battery over heated and the boat was subjected to fluctuation of speed as the power cut in and out towards the end of the race.
Race 2 length 500 m
Air injected at full available rate
Max speed 4.5 mph. 25% faster than race 1 with no over heating due to the reduced drag.
Race 3 length 144 m
As the race length was shorter more power was available and the pitch was increased on the prop.
Max speed 5.01mph which was a increase of 39% over race 1 and enabled my boat to beat you in that race.
Design Data
The air rate used was fixed by the most power full cordless blower then available
Air rate 2.5 cubic m/min
Air pressure 550 mm wc
Air Velocity 72m/s
The under water discharge orifice formed a slot positioned in a 20 mm step and directed along the hull of the boat. At the step the turtle was 0.27 m wide and had 48 orifices 3.75 mm x5.36 mm which gave a discharge velocity of 45 m/s.
You should study
Air lubrication drag reduction on great lake ships
By Michlan Engineering
Fig2.3-2.6
Based on my trials I think that your boat with the 640 watt drive and the 36 volt blower should get a speed increase of over 36% but you could need to change the prop.

 

The craziest 0-60 times were on prepared drag strip with sticky substance etc.

one peculiar often over looked thing is how much speed affects the power needed for the same thrust.
P=F*V
Same force at higher speed requires more power. Thus same exact friction can soak much more power at 50mph than at 10 mph.
It's doubtful even close to 1000hp is at play at low speeds but towards the end of the run it is very possible. roughly 2 second 0-60 is pretty crazy.

 

Interesting, but off topic. Still, it bumps the thread.

 

Many whitewater playboats have been designed with concave portion, sometimes called a "foam pile", on the bottom at the center, where I assume foam gathers.

I don't know the exact reasoning for the concave portion. Perhaps it makes it easier to turn or spin. Perhaps it makes it easier to tilt the boat - forwards, backwards, to the sides.

Whitewater boats have also sometimes been designed other concave portions on the bottom - e.g., at the stern. Supposedly for maneuverability as well.

The term is confusing, because other types of "foam pile" exist in the water under whitewater conditions, in particular, in some river features, the surface flow is upstream, and frequently becomes aerated. It is therefore much easier to go upstream in such features. e.g., see another definition of foam pile. But, AFAIK, that upstream movement efficiency is due to the upstream surface flow, NOT to the aeration, which is just a side effect. In fact, many types of boats take advantage of places with upstream river surface flow for efficient upstream travel, not all of which have bubbles.

And in whitewater, bubbles are often an indicator of other features that are fun to play with.

But whitewater playboats aren't designed for maximum propulsive efficiency. They are designed to play tricks, somewhat resembling acrobatics or gymnastics. I've not personally seen any racing whitewater boats that had this feature, but I might be wrong. I suppose you could say that such boats can be more efficient for playing tricks. Is that good enough?

BTW, foam in whitewater can sometimes be a lot less dense than water, maybe especially if there are surfactants (like detergents) present. You can drown paddling through foam. Very low density foam is often found at the base of falls. I think Surfboarders can also drown in foam created when a breaker collapses. I think there are also some well known cases of oil platforms sinking when gas bubbles are released from below.

If I had to guess, a layer of foam in water, created by something external, might reflect sound of some frequencies (and maybe light too), and might therefore be useful for hiding submarines - but that is only a guess. Also, the collapse of the bubbles might generate noise, which could also hide a submarine - assuming the layer is not generated by the submarine. But that wouldn't be to increase efficiency - just stealth.

Dolphins sometimes use bubble nets - they surround a school of fish by bubbles, to herd them in for an easy mass kill. But again, not for propulsive efficiency.

Do I have this right?: foam next to a normal ship would interrupt smooth laminar flow, increasing wetted surace drag. They would also make it easier for streamlines to separate from the ship, rather than converge at the stern, increasing wave drag? Not good things if you want propulsive efficiency.

Also, bubbles created by propeller cavitation are often said to be a waste of energy, reducing propeller efficiency.

I don't think hovercraft qualify, even they do ride a cushion of air, and some of them can be quite fast, like an air hockey puck, because they are supported by an entire layer of air, not by bubbles.

Surfactants have been used in racing boats of many types - paddled, sailed, motor - successfully. They have also been banned by some racing organizations. I assume the idea is to create a more laminar flow, reducing drag, not to support the weight of the boat, though I don't know the details.

Wax has also been used to make race boats more efficient - I think mainly to make the hull surface smoother. But I think I recall reading somewhere that there are other perhaps equally effective but longer lasting ways to make a hull smooth, like painting and sanding. Perhaps the net effect reduces rather than increases the number of bubbles?

But oil or grease often create a long-lasting dark wake, as seen by backscatter imaging radar (backscatter is when you send out a signal, especially at a low angle to the surface, and it reflects back at you) - probably indicating the surface behind the leaky ship is much less rough, though I am out of date on this, and was never an expert. Perhaps it simply creates a more viscous surface layer - which again is less rough, and perhaps has fewer bubbles. Given that most countries outlaw significant oil or grease leakage, because this can be quite unhealthy for the environment, this has sometimes been used to find ships that break those laws. AFAIK, it does not make the ship more efficient.

Anyway, my conclusion is that bubbles can be useful for many purposes. Just not the one the original poster wanted.

 

First, any type of movement of air across a wetted hull is a type of air lubrication. This includes skirted and hard skirted ses vessels, air bubbler systems and more. In use any reduction in friction between the hull and water increases efficiency. Working with Air Ride Crafts SeaCoaster design was unique and eye-opening. The test results from ONRL proved it could be done in a twin hull SES. The working platform had elements Burg and Harley worked together and added a hydrofoil between the hull forms for extra lift and stability. Harley has continued the work on his form. The focus of air lubrication is to improve overall efficiency without losing load capcity. I am seeing many posts that distort the facts. The test data and reports are available. The results were eye opening and compelling. Why advances in this area have not progressed is simple. Shipyards have licence agreements they can't violate and typically and not willing to venture out of there comfort zone. In the military arena it's more about money and who pays the most. I leave that there.

Most advances in hull forms that incorporate advanced air lubrication comes from individuals who have an idea over marine architects who stick to what they were taught. This too extends to most marine engineers. As a marine engineer I look at data and test results to form my opinion. Nor conjecture and hyperbole. I think the a a twin hulled semi surface effect air lubricated hull is not just feasible it was proven. Test data I have from ONRL show the SeaCoaster had a sprint speed of 80+ knots and cruise of 40+ knots. Test data on a full scale vessels built to test the platform.

From stepped monohulls to air washed hulls and twin hull semi surface effect vessels, air lubrication has been proven to work. It is all in how its done.

 

So many successful demonstrations.....

Yours truly had the unfortunate experience of trying to deliver the Burg Air Ride ferry from LA to NY back in the day.

Then there was Purrseaverance, of course....

 

I don't know what your backround is. I worked with Don Burg on aspects of the SeaCoaster and assisted in agregating numerous tech to enhance and improve the vessel. The last iteration being very successful. I don't know recall a single SeaCoaster being on the west coast unless you are referring to the Ship Yard, Austal in Lousianna. The AVH SeaCoaster. Don Continued to work through the design with substantial improvements.

In a reference your claim to be a coast guard officer, or a vessel designer, now a delivery captain. Not sure what's up, but I know the SeaCoaster, Don Burg and The Harley ship design from Howard Harley, at Harley Boat Corp.

Your opinions are way off base on air lubricated hulls and the efficiency of the SES designs.

But I am just a Licenced Chief Marine Engineer with an unlimited horsepower endorsement.

 

Tsen66,

Welcome to our Forum.

An unlimited horsepower endorsement as a "Licensed Chief Marine Engineer".
That's infinity! I can't even imagine that much power.
Incredible.

Wow, you sure know a lot about what other people don't.
How can you be so clever? Gifted I suppose.

What papers have you written, reviewed and/or co-published?
And what books have you written that we could reference?

Are you on any medications we should be aware of?
If so, do you take them regularly?
(This has come up before, trust me on this one.)

Please consider elaborating on a new thread.
Either way, please elaborate on your incredibleness.

Thanks so much for visiting our little Forum, you're amazing!

BB

 

I am not an expert.

But, at least about 10-20 years ago (I'm not sure about now), when I was taking group lessons from Eric Jackson and company (who were competitive whitewater playboats) many whitewater playboats and I think surf boats (for surfing shore break) had what was called a foam pile under the center of the boat - i.e., a concave roughly partial ellipsoid spot. The idea, I think Jackson said (or maybe it was David Knight, who designed, with Erics help, the boats Jackson and company were using - and who had a background in Naval Architecture as well as submarine design), was that foam would gather in that spot, in place of water alone, making the boat easier to turn, maneuver, and maybe do some types of "freestyle" tricks (which at that time was sometimes referred to as whitewater rodeo). BTW, none of these were inherently fast boats, paddled on flatwater.

In addition, I think the concave spot helped emphasize the "edges" - whitewater kayakers and canoeists sometimes deliberately bury on front or back side edge, to drive the boat into vertical stance moves. A little like the bottom of figure and hockey ice skating blades has a concave cross section to create stronger edges.

Like all such boats, they were designed primarily for front surfing waves. By sliding down the front of a wave, gravity provided the force that allowed them to have a substantial amount of speed, which allowed them to plane somewhat (in the sense that they rode higher than Achimedes principle would specify when the boat isn't moving with respect to the water. And turbulence created the foam, not deliberate active bubble injection. (Foam sometimes dominates whitewater boating - in certain conditions it can be deep enough that whitewater boats sink, and paddlers can drown in it, especially after large drops, like waterfalls. My suspicion is that surfactants such as detergents, sometimes play a role there. In addition, aerated water can greatly affect density and water clarity.)

The boats in question, from the manufacturers, were single person closed deck kayaks (K1s). But sometimes they were adapted into small closed deck canoes (C1s), by replacing the seats with platforms on which you could kneel.

I do not know how common concave centers are in the most modern playboats and surfboats. I also don't know whether these moves are especially common now. Though many whitewater boats have a concave section on top, at the ends, or in other places, to simplify doing forward and backward somersault-like moves, and perhaps (I'm not sure if it helps there) cartwheels, which you initiate by burying one end of the boat under a crashing wave or hydraulic. It should be noted, that many people have gone back to earlier generations of boats now, so they are using boats like that.

It should also be noted that some kayaks and canoes, left out in the sun, develop "oilcan" concavities, which might be mistaken for the deliberate concavities I am talking about.

I do not know whether foam and otherwise aerated water play a role in allowing such boats to plane. I.E., whether there is any reason why aerated water (which is less dense) would make planing easier to achieve. Intuitively, I think it might make it harder.

But I assume by lubrication, you don't mean to enhance maneuverability and tricks, like I am talking about. I assume you want to lubricate for speed, and under less turbulent conditions than whitewater and surf playboaters favor. AFAIK, the fastest competitive whitewater and surf boats for downriver boating, and for the most part slalom racing, are displacement hulls, and never had foam piles.

I believe some racers in many boating categories have used wax, possibly oil, and surfactants for lubrication - but I'm not sure that all racing competitions allow that sort of thing. It is possible such deliberate surfactants could help generate bubbles. (Of course, it is very common in certain classes for people to sand and/or paint boats before a race to make their skins smoother, but I guess that isn't related).

I suppose hovercraft might incidentally create bubbles in the water below them... I'm not clear if or how that would help anything. And it is certainly true that hydrofoils sometimes create bubbles. I wonder if that is a cavitation phenomena. Again, I'm not sure that it helps - as a matter of fact, if I understand correctly cavitation is generally seen as a bad thing for propellers, though that might have to do with the damage it can do to them.

 

I see nothing in my post where I claim to be a "coast guard officer" nor "delivery captain".

I've headed up the design team for a few SES' over the years though and have spent a lot of time underway on them over the last 37 years I've been doing that. ;-)