The Bernoulli Effect


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Okay, several years ago here in the DC area there were several instances where small light aircraft were rather suddenly bounced out of the sky by some unseen force. It was later discovered that this nearly always happened after a large jet took off. Studies were done and it as found that there was a large wave or air that was created by the jet merely going through the air space that would bring the small plan down tumbling.

Well, my question is this: please note that when I was trying to find out infomration, I discovered the term Bernoulli Effect on Richard Edkins web site.

It seemed to me that when a ship is traveling at a high speed and it sits very deep into the water, it would tend to bring things into itself. The New York, Hawke, and now I find that the Fort St George met a similar fate with Olympic. The Ft St George captain felt that he had plenty of room and even witnesses felt that he did as well. He stated as did others that it seemed as if his vessle was drawn into the Olympic. Needless to say the Ft St George captain and crew were found to be negligent. Hmmm. I think that this is worth looking into guys.

The Ft St George case is Federal Reporter Volume 22 (2d) 22 F (24) 195 of the DC SD NY July 29, 1927. Any thoughts?
Maureen.
 
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Dean Manning

Guest
Hi Maureen!

I think I may be able to help you here. The Bernoulli equation (which has an effect, which I'll get too...) uses the conservation laws of energy and mass in an attempt to describe fluid flow given pressure differentials. Does this sound like Greek?!

In any case, the implication is simple, if you have two points, one with a lower pressure than the other, the fluid will flow to fill in that pressure difference. Note here that fluid comprises not only things such as water, oil, ect, ect, but also air. There are plenty of examples of this phenomena around us. For example, when wind blows across a chimney, it creates a lower pressure at the top of the chimney than at the bottom of the chimney. The result is that the air rushes to the top, and carries the smoke with it. Another good example is a drinking straw.

In the case of a ship, remember I said that ships displace water, and that after the ship leaves a particular space, the water rushes to fill back in. That is an example of the Bernoulli principal.

It might also be noted that the equation is by no means flawless. It gives a rough estimate as to what may happen. For instance, I calculated the flow of water through a hole with an area equal to 12 square inches at a depth of around 28feet below the water's surface. I got a flow of about 15tons\second. This figure doesn't come close to the 7 tons\sec the water was rushing in the Titanic.

later!

-Dean
 
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Okay Dean, you've got me now. I guess what I am trying to get at...would it be possible that this Bernoulli principle could have been at work to actually draw the iceberg into its path. That the iceberg was not in front of the Titanic, but on the side of its path...but this effect on the water drew the iceberg into the ship's path just at the last minute.

I gues that I keep thinking that the crows nest and Murdoch seemed to almost work in tandem as if they saw or noticed the berg at the same instance. This could possibly be due to the "movement" of the berg rather than by cahnce that these men saw it at the same time. A person's eyes are drawn to movement and will notice something that moves rather than an idle target much sooner. When something moves in a room the cahnce of people turning to see the thing that moved is higher than if the thing is already in place and does not move.
Like witnesses and what they see or remember seeing during a hold up or robbery or such things.

Anyway, just curious. And the fact is Randy, I am switching to Kaisar Rolls in my research of the Wilhelm.
Maureen.
 
Jul 9, 2000
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Mo,From the Flight training I've had, I can tell you a thing or two about what aviators call wake turbulance which is the effect you mentioned in regard to the unfortunate light aircraft. It's one of the consequences of generating lift. Air flows over the wing with high pressure on the underside and low pressure created as a given volumn of air flows over the greater distance of the curved upper surface of the wing. At the tips of the wings, the high pressure air beneath will be drawn up and over to the zone of low pressure in a swirling and turbulant mass known as a vortex. This effect is reletively negligable with small general aviation type aircraft, but it can wreck you if your behind one of the big boys. It's been known to litterally flip small aircraft over on their backs.

I have to confess to some surprise if the incidents in DC were recent as the wake turbulance problem has been known for a VERY long time. I had training in how to avoid it...and my usual practice was to keep a long and very respectful following distance whenever I was in line behind a large high performance aircraft in the pattern. (I prefer to land right side up and under control, thank you very much.)

Dean Manning has covered the effects your interested in in the water. He's another one of the fine researchers that I look forward to hearing from anytime I come on this board.

I'm not sure it was much of a factor in the Titanic's collision with that iceberg though. The Titanic was a 52,310 ton ship at full load displacement. That iceberg was at least a quarter of a million tons, and that's a lot of inertia you have to overcome.

Cordially,
Michael H. Standart

Cordially,
Michael H. Standart
 
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Great to have you back Sir Standart. I have rumored around here that you were perhaps deep in books, reading.

The incident in DC with the planes was a very long time ago, but I had remembered it and thought it might impact things in the water as well.

I am not sure, but I thought that somewhere someone had mentioned the iceberg at a much lower volume than 250,000 tons (60-70,000 tons) and fully loaded I thought Titanic was over 60,000 but then I've been wrong before...at least once...

Anyway, I wonder if Dean is back from his mission to the copying shop for those 5,000,000 copies of that information for all of us? Dean?

Bill Desena probably knows all this stuff but isn;t telling us.

BTW Michael, flight training? Is there anything that you haven't done fine sir?

Maureen.
 
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Dean Manning

Guest
Hi guys!

First, thank you so much for your compliments, Mr. Standart! I as well find you very knowledgeable and look forward to your posts!

As far as the Bernoulli theory is concerned, you can read about it in just about any physics book. As soon as you mentioned the Bernoulli effect, I got whipped into bad memories of a crappy physics professor I had my freshman year.
happy.gif


In any case, I agree hole heartedly with Michael about the Titanic drawing the iceberg towards it. The massive displacement of the Titanic is very powerful when interacting with objects of a lighter or just a bit heavier nature than her. The iceberg, even it was on the smaller side, had a mass many times that of the Titanic.

One other note. The 52,310 tonnage that Michael quoted is about right. Just as a side, that number, which represents the weight of water the Titanic displaces is the actual weight of the ship. The gross ton is misleading, it's actually a number that reflects the interior space of the ship.

I'm off to dig through and go to the copy shop tomorrow. You should be receiving e-mail from me shortly.

I'm going to bed. It's 3:30am. Good night.

-Dean
 
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Dean Manning

Guest
One other thing I forgot to address. Keep in mind that Frederick Fleet rang the warning bell three times before he telephoned the bridge. It could be possible that Murdoch heard the bell and scanned the horizon himself. By the time Moody got done with the conversation with the crows nest, Murdoch may have spotted the berg.

Just a thought...

Ok, now it's 3:40am. I'm going for real this time!

-Dean
 
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Dear Michael Standart and Dean,
Okay, many humble apologies my dear sir standart, sorry you work for a living or was that Erik,...hmmm....anyway. I did warn you that I had been wrong before....anyway....sorry Michael...and sorry that I kept Dean up so late.

And Dean you have a point about the bell and the response time for the phones and what not.

Thanks for the information and not blasting me in the process...you guys are always gentlemen ...first class.
Maureen.
 
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Dear Dean,
Sorry about your high school physics professor. Mine was "out there" with his ideas and made us drop eggs from 5 story building in designer boxes to attempt to not break the eggs. And successfully fly a inch square kite and crazy stuff like that. See I am the one who should have had your teacher and you with your brains should have had mine.
I spread rumors on the board that you had been kidnapped by a photocopy shop manager for attempting to copy 7,896,345,000 copies of the same document alledgedly for some members of ET.
Enjoy your day. Maureen.
 
Jul 9, 2000
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Just for the information of all, my source for the full load displacement of the RMS Titanic came from the report issued by the British Board of Trade, page 7, and is calculated on a draft of 34 ft, 7 inches.

Mo, my flight training was with general aviation type aircraft and I started it when I was stationed at Naval Air Station Keflevik, Iceland. They had a nice flying club there with a single Piper Warrior. I found myself flying in all sorts of conditions from an airfeild used by some VERY large military aircraft as well as civil airliners. Avoiding wake turbulance was something you learned damned quick if you valued your life.

Is there anything I haven't done? Well, I never joined the notorious "Mile High Club" Something about having at it with a lady freind in a crowded aircraft in a seat designed by the Spanish Inquisition just doesn't work for me. Now bring on the wine, soft music, candle light...and a nice even bed so my chiropractor doesn't say, "You messed up your back HOW?"

In regards to icebergs, size varies quite a bit from small growlers which weigh in at only a few tons to some real monsters which can tip the scales at several million tons. What complicates avoiding them at night is that when they melt, they'll turn over so that what shows is a nearly clear mass with no tell tale white frost on the surface to make seeing one a little easier.

Dean, your kind words are much appriciated. As to poor science teachers, I can sympathize. I've had some that were so bad, it was a wonder anyone learned anything in their classes at all.

Cordially,
Michael H. Standart
 
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Dear Michael Standart.
I am impressed with your flight experience and your knowledge base for my wave question. Thanks.

The information about the icebergs was great as well. Several million tons...it makes you wonder how they float. I mean I know the physics and chemistry of water/ice and what not but it seems impossible and yet it does.

Oh, and don;t think you got off light with that comment up there somewhere...."having at it with a lady friend in a crowded aircraft in a seat designed by the Spanish Inquisition" ...Mile High Club.... versus wine, soft music, candle light and a nice even bed....

Well, I would never ever be able to join the mile high club because I have never had at it with a lady friend in a crowded aircraft either...however I would like a try for membership in the ground zero club someday with the right guy, right wine, right soft music and the right candle light...I figure it this way...right guy and just being with him would make the bed nice and even! Of course, there would be the checking to see if it were a moonless night and the refraction of the rocket making it seem blue and all. All for science right.
he he Maureen.
 
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Dean Manning

Guest
hi!

Just a thought or two. You guys are a trip! I laughed hysterically when I read the above posts!

For whatever reason, I trust the inquiry report with regards to the actual draught and displacement. I've heard the 66,000 ton number, but to me this is just another one of those things that's been blown way out of proportion.

One more thing. Because I'm anal, I need to point out that it was a college prof.

I'm sorry about the delay with the article. I had three exams this week.

later.

-Dean
 
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Sorry Dean. College Professor Physics Teacher. Not High School. Mine was my high school teacher and he was this older gentleman with a wonderfully groomed handlebar moustache and black thick rimmed glasses. He took us everywhere and taught us all kinds of things. But he retired after our class I think...my questions got to him too.

You just do well on those exams and get those things to us when you can. you are great Dean!

Glad you enjoyed our humor.
Do well on them!
Maureen.
 
Jul 9, 2000
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G'day Mo; another reason the Mile High Club didn't tempt me; turbulance! I'd rather make my own in a safer place, that way you see the rockets when you want to rather then stars when your skull meets the luggage bin.(Ouch).

Dean; THREE exams? I hope you found some time to catch some sleep. Otherwise, somebody's going to take you for a refugee from the Zombies Convention. I think you're right about that 66,000 ton figure too and the way it parts from reality. Some stories tend to improve with age. I'm just glad I have the BOT report, the transcripts and the Shipbuilder articals. There's little so precious as having the primary sources right at your fingertips.

I'll echo Mo's sentiments in re the exams; you just do the best you can. We're rooting for you.

Cordially,
Michael H. Standart
 
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Dean Manning

Guest
Hi Michael and Maureen!

This may sound like a really stupid question, but, what's the BOT report? I have a copy of the transcripts which I acquired on line. I have yet to get the Shipbuilder articles, although, I have been able to down load some of them off the internet.

Also, I'm not to sure how interested in propulsion you guys might be, but I ran across this web sight that you may want to check out:

http://www.history.rochester.edu/steam/parsons/

I haven't had the chance to read all the links yet, but supposedly this page deals with turbines, including low pressure parson types which were used in the Olympic class ships. Also, you may want to check out the "steam engine library" link, which contains a couple of interesting links, including one called "A history of the growth of the Steam Engine".

One other thing. I can't thank either Maureen or Michael enough in their interest in my academic pursuits. Both of them barely know me, yet they are, as Michael described, both "pulling for me". I can't thank them enough for their support!

Later.

-Dean
 
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Dean.
We're actually quite selfish folks(that is Michael and me). See ,we're hoping to get you all "fatten up" with knowledge see and then we have this brilliant resource later. (he he)

Actually, can't speak for Michael, but quite frankly I went to college right after high school and majored in Music, got married, did not use my degree in the way that I could have and then was a single parent and went back to college to major in Computer Science in order to survive.

Now, nn my job, I have to learn many things on the fly and pick up and go running with things so you learn to appreciate time as an entity and boundaries, yours and others.

School is important and supporting a friend in their achievement of their educaiton goals and respecting their boundaries is what it is all about. That is what friends are for! (Well, and also to learn about things like Mile High Clubs and the after effects of turbulence so that one does not have to actually experience these things for one's self.) You are great Dean and I am glad that you are here. You are definitely value added here.
Maureen.
 
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And no Michael Standart, I did not forget about you. Thanks for your educational pointers on turbulence. Next time I am in that Spanish Inquistion Chair(SIC) I will try to buckle up...no wait....what I meant was...I mean, when I ever am ever in that SIC position I will remember your warning and buckle up! Hmmmmm....I know that my imagination is really going crazy. We've most likely placed Pat into a staring frenzy to his screen and Mike Herbold has permanently bonded with his golf balls. So we had best stop this Mile High talk or Phil will zap us.
Maureen.
 
Jul 9, 2000
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Get some sleep Mo. Exhaustion is clouding your mind. ;-)

Seriously, I wish I had the time and the patience for further formal education. I went into the Navy right out of high school. I had to pick up what I could from books...a helluva lot of books! And I've had to be careful about the source material that I obtain as there is a lot of flotsem and jetsum floating around out there that was a waste of a forest to publish. Fortunately, there are people here who can help sort out the trash and point the way to sources that can be trusted.

Dean, the BOT report I referred to is the "Report of the Loss of ther Titanic (S.S.), The Merchent Shipping Acts, 1854 to 1908, Report of the Court, Dated this 30th of July 1912" It's the report issued by the investigation conducted by Lord Mersey. If you have the link to the transcripts on line, it should be in there. I'll be checking ouit that link you offered. Looks like something I may be bookmarking for future reference. Thanks.

Cordially,
Michael H. Standart
 

Inger Sheil

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Feb 9, 1999
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Maureen-

Re the Hawke and the Olympic collision, there's some tremendous material in the PRO - boxes of evidence, including many letters from individuals (many of them RNR or ex-RNR) who wrote to Churchill to report that they had feared the effects of the large new liners on smaller craft. I was looking for specific WSL material, but found myself rather distracted by these fascinating unsolicited accounts of what these mariners thought of the large ships.

On the other hand, there were those who shared the view of one Wadley, who wrote to Seabreezes in the 50s to recall the outrage that many witnesses felt at the Olympic being held at fault. The letter drew the following response from pilot Bowyer's daughter (the WSL was exonerated on the grounds of 'Compulsory Pilotage):

I was most interested in Mr Wadley's eyewitness account of the collision between HMS Hawke and the Olympic (August Issue). My father, the late George William Bowyer, was the Olympic's pilot while her master was the late Capt. EJ Smith.

My father, in his book 'Lively Ahoy,' reminiscences of 58 years years in the Trinity House Pilotage Service, states: "I had a clear conscience which nothing on earth can alter. The case was taken to the House of Lords, but the verdict was not altered. However, the company thought we were right and I have piloted the Olympic, Homeric and Majestic up to my retirement on December 31,1929.

As Mr Wadley mentioned the verdict caused a storm of indignation; it was a decision that was absurd and unjust.

PI Johnson (Mrs)
Milford-on-Sea
Hants
 
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