boats that are designed with car aerodynamic method?

Ok but do you have any comments on the post #41?

 

Be it hydo or aero the main point to all this is making better shapes that will slip through and over the surface of the water and throught the air much more efficently than the shapes of boats today that have not really changed very much at all since the 1920s and before !
Hydo is only a part way ,you need aero as well !!,its a whole pacakge deal not a part of !!! why do one without the other ?. with powerboats that get up and go it has to be both ,plus weight has a big influance in all this and comes into it as well so theres a third thing !!.
Take a heavy brick shape 20 feet long ,it needs to travel at 58 mph continuosly for 12 hours so how would you make it move quickly and efficently through the air and across the surface of the water ?? Theres 3 things you need !! and you have to use the least amount of energy possible to make it move and maintain the speed specified !

In reality this is what is going to be happening in the coming years !!! so you designers have a lot of thinking to do !! How can it be done ??

almost forgot this as well!! how can you stop a wing from producing lift ??



OOh the jet plane is still siting on the runway with it jet engine roaring its head off full out with just its brakes on !! is this possible or not ?? come on need an answer !!:idea:

 

I think the answer to that question is, some of us don't know a darned thing!

I wonder if the question may have originally had more to do with the underwater shape than the topside. I am reasonably sure it had little to do with racing hydroplanes and the like. The comparison with cars is hardly relevant: a comparison between a submarine and a car would make far more sense. Cars are all about looks: from a dynamic friction point of view the underwater shape of even a tug or barge is probably better than the average family car, and a decent rowboat is in another class altogether.

The point that is so easily missed here is, the above-water part of a moderately sized boat is the part that's occupied, and it's limited by the physical characteristics of the human beings frequently found lurking there. Very few owners are willing to tolerate the discomfort required to achieve a 1 or 2% performance improvement when a little additional horse power will do the same thing.

Far greater aerodynamic performance benefits are possible in automotive design than in boats, but those silly car buyers want to put stuff in the trunk and kids in the back seat and even see where they are going. Drag factors for automobiles have improved, from around 0.7 for early models to around 0.3 for the best of today's offerings - a miniscule improvement compared to engine improvements - and it has almost no effect on economy around town where the average family car spends most of its time. It's even less relevant to the average family boat, which rides out even a minor puff of wind safely tied up to the dock.

It's all a question of degree ultimately, and not much interest to a canoist, although when paddling back home against that headwind that always seems to strike up when I'm getting tired, wind drag is able to get my full attention.

 

Tell me why do bikers where fancy slippery cloths and shave there legs smooth and put there helmets on back to front ?? why are the spokes of there wheels flat instread of round like they used to be and like ancient kayaker just stated the wind affects his paddling and its harder into a head wind !! Even walking into a head wind is hard work !
This is all slow speed stuff !!!
Wheres your heads at ?? what are you thinking ???the slower the speed the more you need to have better shapes that are user friendly !! or aerodynamic !! Its all about wind speed not nessasarily the speed of the boat !! if you out in a 20 knot wind traveling at 20 knots into the wind its going to make a hell of a differance to your performance if your boat is all square and boxie !!!but going with the wind theres nothing at all !!
Some people need to get off there hight stools and take a look and see what really goes on in this world we all live in .Need get there heads out of those dark smelly places and see the light and smell all the sweet smelling flowers
I do know some small boat manufactures of small family cabin boats where they changed there cabins and have no side decks and no foredecks and are more rounded and bulbus and are much better handling boats in windy conditions and dont get buffeted like they used to !!
You want to exsperiance wind and its effects try rowing a 8 foot aluminium boat by yourself on a windy day in a rough sea !!.

 

By the way the jet plane ran out of fuel after sitting for two days roaring it engine and it brakes hard on . and it didnt move !! why ??? thahats what i want to know the answer to why didnt it simply skid its wheels and go ???

I have a son in the nz airforce and i went to see him one day on my way past the base and this single engined fighter plane was sitting away down the runway blasting its self full out but not moving . Hes said its ok and the brake hold no problem untill it starts to move and when it build a little speed it reall gets moving in a big hurry . Never ever did find out why it didnt move !!

How do you stop a wing from lifting ??
stall the top surface !!. a small strip sticking straight up is enough to disturb the air flow and cause so much turbulance it will stall the wing and it wont produce lift !!
Neat ahh learn something new every day !! so what did you learn yesterday ?? ummmmmm !

 

Hydro dynamics should play a big part in the shape of a canoe ! you seen some of the really really old eskimo canoes like really old they have a unusual front below and above the water line just like the bulb on the front of our modern ships !! how did they discover that and why ??
We live with blinkers on and really dont see whats around us . just little things !! things that have been handed down for generations . the old saying there nothing new under the sun is true !! its all be done before just they didnt have the materials we have today to refine and make the objects better !!

 

Some interesting things we used and do in our every day lives

http://autospeed.com/cms/title_Low-Drag-Car-Aerodynamics/A_112609/article.html

Its interesting to see how the shapes of things influances the air flow in other parts of a car !!

You into sports try this one http://people.stfx.ca/smackenz/Cour... Aerodynamics and hydrodynamics in sports.pdf

 

This is normal, modern tyres should be able to have a coefficient of friction approaching 1.
As an example the Boeing 767 weighs 175,400lb empty it has two 50,000lb thrust engines ie 100,000lb total, which is much less than 175,400lb. It will not move.

 

Look folks he just doesn't get it. He doesn't appreciate the huge difference between air and water. Cars, bikes, aircraft and bottle rockets don't have to deal with the nearly 800 to 1 density difference that boats do, which is why most pleasure craft don't even bother with aerodynamic considerations. Human powered devices, be they bikes or canoes do have to consider Cd, simply because of the available power. It's not an aerodynamic efficiency thing, it's a maximizing the efficiency of the available power thing. In bicycles, more engineering effort is spent on weight and friction reduction than aerodynamics.

Again, can you get some measurable efficiency improvements with aerodynamic changes? Sure, but they'd be measured in 100ths of a knot, so why bother. You can talk out your butt all you want, but the resistance figures are clear on this, in spite of what you might think is relevant. Then of course we all don't have the brains that you do. We're just out of step in comparison to your towering intellect, on the subject of flow dynamics. You know, the subject we've spent a life time of study with, likely just to catch up to your innate understanding of it.

 

PAR, I have to agree with you... I have almost ran out of arguments, though the examples I've given so far should be very simple and easy to grasp.

But I'll give one last try:
Tunnels, so you like the cars analogy? Ok, let's use one more car analogy. Please answer to this question - why is it that the biggest part of motorhomes are produced with this kind of shape:



Big, boxy and with vertical walls. Yes there are some fairings and round lines, but overall not very aerodynamic. Why?

In the meanwhile, I'm answering your question about that airplane, so that we can go on: the plane is not moving because the engine thrust is smaller than the force produced by the action of brakes and tires. No magic there. And nothing to do with boats anyways.

 

Slavi, I don't understand his refusal of the basics either. Even rockets don't pay all that much attention to aerodynamics, even though they need to travel over mach 23 to get into orbit. They have bumps, protrusions, explosive latches, bolts and all sorts of stuff sticking out if them, but just use a little extra force to shove themselves into space. After you use 100 HP to blast your trailer queen up on plane, does the lose of a couple of HP to a crappy Cd, really mean all that much in the big picture? So if that couple of HP was given back to the boat, with really supper clean aerodynamics, how much more top speed do you get or how much more fuel economy do you get? Measurable, yes, but the 1/2 pint of fuel you save each hour or the 1/5th of a knot you get at the top end, just can't justify the effort.

 

If you guys want to play stupid games you can have it !! so you want to see my skills at figures and calculations and mumbo crap . Well im not into those things I do practical work and hands on and can look and see what works and what needs to be done and how to lke it of not smooth flowing lines on any boat are much better than square mindless shapes and whats been done since man first sat on a log and hung onto a branch and drifted down the river !! You should join him because you havent progess very far since those days .
This is all going no where and im outta here . so belittle me as much as you like !
buy by bi

 

Because of the speed of the F111 and all its strange angles and lack of what appears to be aero dynamics and the rocket you referring to its entred a phase that aerodynamics dont apply to !! didnt you Know that or didnt it register ???? why do you keep dancing away from the purpose of this thread and the origanal question . So far i have not seen and possibly no one else has either any sensable contributions to the origanal question asked !!
whats ya problem
0 great high and mighty person/s ?? go find some one else to pick on !!
any way im outta here

 

See, this is precisely what we've been talking about Tunnels, you talking out your butt about things you don't know. For example, the F-111 is and always was a pig, which required gimmicks to accommodate is SOR, which had to be revised (downward) so it could be acceptable. Maybe you're thinking of the F-117, which does have strange angles, though is also a pig, a not even supersonic pig, in fact.

You've been offered example after example and you've cast it aside, for your own interpretation of flow dynamics, which of course has no bearing in reality. Just admit it, you don't have a real clue about flow or it's dynamics. This is brainiak stuff, which by your own admission, isn't what you want to deal with, let alone understand. Just because it doesn't make a lot of sense to you, doesn't mean it's flawed. It just means you don't understand. Blaming us, for your inadequacies in flow dynamics, isn't the best approach.

 

That’s because they are looking for the extra 1% that most of us don’t bother about and can’t even measure. I rarely shave my legs to go canoeing . . .

My head is in it’s customary place, looking at the whole picture.


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