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 Author  Topic: Some Documents from my Elco collection
  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Dec 15, 2016 - 6:52am
Andy;
That is an interesting photo of PT 613, where did you find it? Also, are there any Port or Starboard photos of this and the PT 614-619 photo(Al's), so we can see the difference from a better angle?
Take care,
TED


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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 16, 2016 - 9:47am
Photo is an ELCO one that is part of the Naval War College collection. The description from the PT613 trials (National Archives) from July 45 is as follows:

The slippers... consist of plywood planes which continue the bottom surface of the boat to a point about thirty inches aft of the transom. Port and starboard slippers are adjusted independently by means of a pinion gear crank which engages teeth on a bronze nut. This bronze nut, when rotated, moves the pipe stanchion and the slipper.

Pushing the slippers down, raises the stern and depresses the bow of the boat, pulling the slipper up has the opposite effect. In each case, the amount of change of trim depends on the speed and loading of the boat.

PT 613 was also testing the new spade type monel metal rudders (design #6223) and 29 x 26 propellers. During the turning tests, the flippers (seems the test guys called them this) were set at an optimum setting for the 124,000 lbs displacement at 1" down setting. This pushed the bow down and gave a trim angle of 3 degrees at high speed.

I've been developing a PT Boat turning comparison chart from data I've collected from 1942 to 1945. The ELCO was by far the turning pig of the 3 types of PT Boats mainly due to the lack of a forefoot which is key to providing the counter forces needed for quick turns. The introduction of the 40mm aft greatly affected its turns whereas I have found no such issues with the Higgins or Huckins. PT 103 did 360 degree turns at 2100 rpm (94,000 lbs displacement - two torpedo tubes, 2.5 degree trim) in 48 seconds to the right, and 47 seconds to the left. Three years later, PT 614 weighing in at 30,000 lbs more, and at 2400 rpm, took 77 seconds to the right and a whopping 115 seconds to the left.

PT 613 with the slippers (flippers) and new spade type rudders (slight wedge shape), and at the same displacement, recorded the right turn in 50 seconds and the left in 49 seconds basically restoring the ELCO to it's original turning capability. For comparison with the Higgins, PT 650 recorded 36 seconds to the right and 35 seconds to the left at 2500 rpm and 117,000 lbs displacement.

I do have some more PT 613 photos which I will post once I locate them.

Cheers,
Andy


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  Jerry Gilmartin

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jerry Gilmartin   Send Email To Jerry Gilmartin Posted on: Dec 16, 2016 - 6:34pm
So Higgins Boats DID handle better than 80 ft Elcos! I knew it. They could turn faster effectively. That is important in trying to avoid kamikaze planes and bombs etc. This proves once and for all the VAST Superiority of the HIGGINS 78ft PT Boat! HAH!
Thanks ANDY!

Jerry Gilmartin
PT658 Crewman
Portland OR

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  TED WALTHER

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of TED WALTHER   Send Email To TED WALTHER Posted on: Dec 16, 2016 - 7:54pm
Jerry;
C'mon man!
All you have to do is look at the rudders. They were too small. with the added weight of the 1945 load out, changed the balance, it would slide the hull, making it harder for the rudders to react and causing them to be even less efficient than they originally were. Also the fact that the ELCO rode at high speed with more of the hull out of the water, Slightly larger props with a different pitch, probably would have helped too.
Take care,
TED


P.S. ELCO's still look better!!

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Jimbo Melanson

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Post a Reply To This Topic    Reply With Quotes     Edit Message   Posted on: Dec 17, 2016 - 3:10pm
Elco's Rule Higgins Drool!





Jimbo

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Jeff D

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jeff D   Send Email To Jeff D Posted on: Dec 18, 2016 - 6:06am
Very interesting and nice work Andy! Keep your eye out for any testing done with PTs 163-174, a drawing of a triangular fin mounted at about bulkhead 9 shows these boats listed. I'm guessing it was added to improve turning but proved ineffective. I had an image of a PT at speed with the bow out of water showing the fin but can't find it...



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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 20, 2016 - 10:04am
I did not know that about the fins on the earlier 80 footers. The Elcoplane drawing No. 3107 (see below) shows a small fin. After the war (Oct 45), there's a mention of installing fins on the RON 42 boats. Adding forward fins was used on race boats in the early 20s. One of the most interesting was the fin added to Oleo III (Hickman Sea Sled race boat). It was installed only on the port side since the race course was to port. The Sea Sled was up against very small and nimble hydroplanes with bow rudders, and while the fin helped the turning, as did the sea sled's faster straight away speeds, it wasn't enough to overcome the hydroplane advantage on the race course.

I've attached another photo of PT613 adjustable slipper and spade rudders. I've also attached two photos of Mr Johannes Plum's Fantail Flipper. This was in a Buships package from Sep 38 and shows the young Dane's invention. The boat was a stepped hydroplane. I'm sure that Elco used this as the basis for their later design.

photo

photo

photo

photo


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Jeff D

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jeff D   Send Email To Jeff D Posted on: Dec 21, 2016 - 9:32am
Again thanks Andy, very interesting! They sure did a lot of experimenting trying to increase speed and turning. And no wonder they used the Fantail design as a start, this article mentions that even with 4000 pounds added ballast the speed remained the same: http://www.woodyboater.com/blog/2016/08/26/its-time-to-play-another-round-of-look-whats-in-my-drawers/

I'll e-mail you some drawing notes on the 487 you might find interesting.

I had a small shallow V R/C race boat that although very fast, my friends that had experience with the hull said would never turn well. I tweaked the strut until it would run straight with zero rudder offset and added a turn fin like the hydros used on the stbd (we ran a clockwise oval course) outboard stern. It ended up faster and turned like it was on rails and had my buds shaking their heads. Sometimes it pays to experiment.



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Jeff D

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Jeff D   Send Email To Jeff D Posted on: Dec 21, 2016 - 10:34am
How about a 6 second turn? ELCO RULES From Dick's An Administrative History of PT Boats available on the downloads page:

The fastest run ever made by any PT and the quickest turns ever made at high speed were undoubtedly accomplished by Elco’s PT 487, which hit 55.95 knots during trials for the Board of Inspection and Survey, and made a 180 degree turn at top speed in about six seconds – a turn so fast that at its completion the boat had sternway on! The secret of this amazing performance was the addition by Elco of five steps to the bottom of a standard eighty foot boat.

The tests on the boat took place on 26 December 1943, and although this was the first time that a PT had ever been equipped with Elcoplanes, as the steps were named, the principle of multiple steps on Elco boats had been conceived more than thirty years before. On 14 January 1913, Irwin Chase, Elco’s design genius, was granted a patent for a hydroplane-boat which was “a boat comprising a buoyant hull having an unbroken surface skimming hydroplane, secured to said bottom surface . . . “ The sketches accompanying the patent show a boat with a series of steps similar to those employed on the PT boat thirty years later.

Mr. Chase's design:





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Andy Small

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Post a Reply To This Topic    Reply With Quotes     Edit Message     View Profile of Andy Small  Posted on: Dec 21, 2016 - 10:40am
Thanks Jeff! The Buships notes on the Fantail are very interesting and maybe someday I'll transcribe all the pencil writing from their evaluation.

For those who have not done so, I highly recommend going to the National Archives to research all the amazing materials they have. I'm a research hound and love to find new things and fill in holes and create new ones My favorite parts are the sometimes sarcastic engineer comments written in the margins or in the routing memos.


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