Titanic's propellers


Jan 5, 2001
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The graphic below which you showed as proof is not accurate...It is a manipulation to create the false impression that the blade is completely hidden underneath

Aaron, there was no manipulation involved and I certainly don't think there was any intent to 'create' any sort of false impression.

Best wishes

Mark.
 
A

Aaron_2016

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The diagram below was presented as proof that the blade is hidden by the alignment of the blades, but the overlay image is not in sync with the propeller behind. This is I believe a form of manipulation to create the impression that her blade is completely buried.


The overlay image is not aligned with the middle of the top blade.

upload_2018-8-26_16-34-55.jpeg



Left - shows the wrong alignment. Right - shows the right alignment.


direction.png





Below we can see both sides of the starboard propeller. The gap between each blade should be equal, but we can see the difference is very noticeable.


upload_2018-8-26_16-44-10.png




.
 
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Mar 22, 2003
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Aaron, there was no manipulation to create a false impression. It was merely an attempt to use 3D graphics of the 3 bladed prop so it can be oriented into having the exact same view as is in the wreck photo. The 3d prop was of an airplane prop which is why it is relatively narrow. I tried to get the leading edges aligned so they are parallel to the two leading edges of the two blades that can be seen on the wreck photo. What this shows is that if a blade is there, it would be buried under the sand. To claim that the blade is actually missing, or was broken off before the stern section hit bottom, in my opinion, requires some solid proof that has not not been offered up yet.
 
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Aaron_2016

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I agree the alignment was an attempt by your good self, but it was used by another member as a source of proof to dismiss my claim that the blade is gone. I merely proved that it was not a justified means of proof. The gap between each blade should be the same but we can see on photos of the starboard propeller how close the blades were on the right side, and yet we see how far apart they are on the left side. That discrepency needs to be addressed, but seems to be ignored as a wild claim made by me when it is so obvious that both sides are not the same distance apart. So there is yet to be any convincing evidence to suggest the blade is still there.

.
 
Jan 5, 2001
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Aaron, regardless of the merit of that statement - it's one I disagree with - the burden of proof is on you, not anyone else.

If you're making a claim, it's incumbent upon you to support it. It is not incumbent on others to disprove it, even if they chose to do so. (For instance, if I claimed that Captain Smith's sitting room was fitted with pink carpet, I would expect to be challenged on the matter: it would not be appropriate for me to ask others to disprove it. Rather, the burden of proof would be upon me to show that there was a carpet and that it was coloured pink.)

Best wishes

Mark.
 
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Aaron_2016

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Agreed, but like I said, nothing convincing has been provided to suggest the blade is still there. After reading survivor accounts and observing the photographs I am convinced the blade is not there for the same reason we believe the Titanic struck an iceberg and broke on the surface. We have faith in the survivor accounts. Withstanding that we have photographs of the starboard propeller which shows the large gap where the mounting and bolts should be, and they are not there. We also have a large smear on the sand which examiners believe was caused by the stern when it landed and smeared itself against the sand as it rotated and came to a stop, yet we have no evidence at all that the third blade is still there. No scarring of the sand as the propeller smeared clockwise with the stern, and no mound of sand adjacent to the propeller that would be driven up by the deep impression of the third blade if it were underneath.

There's just nothing there and no reason to believe the blade is there. I can't be forced to believe something when there is no evidence to suggest it is there. A number of survivors made the claim that a blade had been lost. The photographs I believe prove their claims are true. I can't disprove their claims because there is nothing to convince me otherwise. Until a proper exploration of the starboard propeller is made all I can do is repeat what the survivors said and what I can observe from the photographs.

Best regards.

.
 
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Mark Baber

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Moderator's hat on:

Folks, Adam's belief that a blade was missing has been thoroughly discussed elsewhere and the enormous pictures posted in this thread have appeared on the board a number of times. Let's not re-create the prior discussion here.

Moderator's hat off.
 
Mar 22, 2003
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A number of survivors made the claim that a blade had been lost.
There is a difference between what something feels like and what actually took place. And if the blade is missing, which has yet to be proved beyond any doubt, the question then is when did that particular blade break off, before or after the stern reached the sea floor?

I recall some years ago an incident that happened when I was taking a check ride in a Cessna 152 with a flight instructor that belonged to the same flying club that I did, a guy by the name of Frank Fine. We took off without incident from our home airport in Marlboro, NJ, when upon reaching a height of about 500 ft, or thereabouts, something shattering seemed to happen, with the plane shaking like something drastic to the prop took place. It was a feeling that something was very unbalanced, and the thought that something happened to the prop actually crossed my mind because of the feeling that took place. I immediately pulled the power to reduce the shaking hoping to stop the engine when Frank called out "I got it!" and took control of the plane and did exactly what we were taught never, ever to do, and that was to turn back and try to put her back down on the runway. Well, we make it back on the ground OK, and as they say, any landing you walk away from is a good landing. Well, I asked him what just happened, and he said we probably blew a cylinder head, or something like that, but we had 3 other good ones which he thought would develop enough power that if needed would allow us to make the airfield instead of putting the plane down in some recently plowed farm field that was in front of us. That was the shortest flight I ever took. The prop, of course, was intact, but I think I began to shake almost as violently as the plane did after we got out.

PS - I never asked Frank where he developed that bad limp that he had. However, someone else told me that it was from some accident a long time earlier in his career, and he came out of it in worse shape than the plane he was flying. I asked how could that be, and was told that plane was fixed and put back in service before Frank was able to fly it again. My only response to that story was, "Oh,OK."
 
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Nov 14, 2005
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That must have got the heart rate up. I never had an engine failure flying so I cant relate to that. Of course we all practice for that but its not the same. I did have one bad flying day I remember. I was flying over the desert in summer. Most people fly out here in the morning or at night if they can. I took off flying back home and got about 5 miles from the airport when the port side engine access cover came open and was flapping and making a racket. I decided to go back and land. I was able to fix it so it stayed shut. Took off again and about half way home I hit some really bad thermals and was dropping 4 to 500 feet before hitting flyable air again. It was slamming me around really bad and had me rattled a little. Between that and the cover being loose I was not at the top of my game when I came in to land. Everything was fine on the final while I was over the cooler farm fields but when I crossed to the hot blacktop of the runaway and the hot air (less air density) I dropped liked a rock about 10 feet and bounced about 3 times. I knew better and should have grabbed more flaps and more power. I don't drink but after that I went and had a few beers. Later on as time went by a few people said "you like to come in and land a little hot don't you". I said "yes, yes I do"..*L*.

P.S...as for propellers. None of the instructors I had ever covered this but a crop duster pilot who was also a Vietnam fighter pilot told when when doing your pre-flight give the prop a rap with your knuckle and listen for certain sound like a pinging. If it has internal cracks not visible the 2 props will sound a little different and there could be a problem. It sounded logical to me so I got in the habit of doing that on my pre flights. Never found anything that sounded different.
 
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Rob Lawes

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when when doing your pre-flight give the prop a rap with your knuckle and listen for certain sound like a pinging

That's how rivet quality would be tested back in the day. Men would go around with a hammer and tap the rivet head. If there was a dull thud instead of a ping then the rivet was faulty and would have to be replaced. Railway men also used the same procedure to test the wheels of trains to ensure they weren't cracked.
 
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Mar 22, 2003
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Good advice Steven. As you know, the biggest problem with props is the blades getting dinged by small rocks on dirt fields. A little nick on the leading edge will almost always get larger over time. A hidden crack could be catastrophic. I like the ping test.
 
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Thanks! The credit goes to that crop duster pilot. I would always shoot the breeze with him every chance I got because he had so many good tips from a life time of flying. Besides being a nice guy he was the best stick and rudder flyer I've ever seen.

Rob..that makes sense. I didn't know that about the rivets and the trains. I wonder if they still do that or have a more sophisticated way today...like scheduled x-ray scans or something.
 

A. Gabriel

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There are confusions I have which I hope can be addressed. In the Speed and Revolutions article, Mr Halpern mentions the area of Titanic's center screw as being 125 square feet and the pitch of the wing screws as being 34'6". However, according to the esteemed Mr Chirnside in the article The mystery of Titanic's central propeller , the wing screws' pitch is listed as 35' and the area of the center screw as being 120 square feet (the same as Olympic's).

Would this necessitate a recalculation of the speed/revolution/slip table?
 

A. Gabriel

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Unable to edit so I must doublepost, my apologies. Permit me to rephrase my query in a more exhaustive/technical/scientific manner:

Footnote 10 in the Speed and Revolutions article mentions that the thrust produced by Titanic's center propeller was (125/120) = 1.04166... times greater than that produced by Olympic's. Since the center propeller produced (16/46) of the total thrust, and since according to the article Titanic's wing propellers were of the same dimensions and pitch as Olympic's, the total thrust produced by all three propellers is

1(15/46) + 1(15/46) + 1.04166...(16/46) = 1.0145 times greater than the total thrust produced by Olympic's propellers.

Now, if I were to substitute the propeller dimensions from Mr Chirnside's article, the (125/120) term becomes (120/120)=1 since Titanic's center propeller is noted to have the same area as Olympic's, with only a difference in number of blades. However, the pitch of Titanic's two wing propellers is now listed as 35.00 feet instead of 34.50 feet. How does this affect the thrust produced, i.e. what is the relationship between pitch and thrust? The resulting value x will replace the ones in the 1(15/46) terms, so the final thrust expression for Titanic's screws versus Olympic's becomes

x(15/46) + x(15/46) + 1(16/46) = improvement over Olympic's thrust, to be determined
 
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Mar 22, 2003
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Hi, A. Gabriel. You can address me as Sam, no need for formalities here.
I have to go back and take a hard look at what I wrote in the article. It has been some time since it was released. But from what I do recall, the thrust of a propeller for a given number of revolutions, will go up in approximate proportion to the increase in angle of attack before it starts nearing the stall point. And of course the angle of attack is proportional to the pitch. But I have to go back and look at all the numbers. I' will get back to you.
 

A. Gabriel

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Looking forward to it! Looking at Olympic's speed/rev curve and associated table brings me great satisfaction in seeing just how decent the propelling machinery of Old Reliable was, and it is my hope that understanding the various relationships between speed, power, thrust, and pitch will allow for the creation of speed/rev curves and tables for all the Olympic-class: for Titanic, Britannic, and all of Olympic's numerous propeller refits.
 

A. Gabriel

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A. Gabriel,
My article, 'Speed and Revolution' that is on this site is a much earlier version which has been subsequently revised on 16 October 2015, and can be accessed here: Speed and Revolutions.
Sorry for any confusion that this may have caused.
Cheers,

Many thanks Sam. So it would seem, going by the derivation in your revised article, that speed is linearly proportional to pitch, as the equation for Titanic is to be found by multiplying that for Olympic by the ratio of the propeller pitches:

V(Titanic) = V(Olympic)*(35/34.5)

With this assumption in mind, and taking into account the other factors (speed proportional to square root of thrust, and to cube root of power), I present here a rough model of speed/rev tables for all the Olympic-class liners at the various stages in their lives, using the speed/rev equation for 1912-era Olympic as the baseline.
 

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