Advanced search  
Pages: 1 ... 4 5 [6] 7   Go Down

Author Topic: News July 9 1937  (Read 81164 times)

richie conroy

  • T5
  • *****
  • Posts: 1412
Re: News July 9 1937
« Reply #75 on: February 15, 2012, 01:52:29 AM »

very good points harry and gary

so she basically was sole reliant on noonans navigational skill's an RDF

now does Earhart's RDF Loop antenna, work the same way as the one itasca had on howland island

I.E you had to rotate it left or right to pick up a signal ?

an that would mean that the loop antenna had to be "dead centre" to plane for it to work properly ?   
We are an echo of the past


Member# 416
 
Logged

Gary LaPook

  • T5
  • *****
  • Posts: 1624
Re: News July 9 1937
« Reply #76 on: February 15, 2012, 03:14:47 AM »

very good points harry and gary

so she basically was sole reliant on noonans navigational skill's an RDF

now does Earhart's RDF Loop antenna, work the same way as the one itasca had on howland island

I.E you had to rotate it left or right to pick up a signal ?

an that would mean that the loop antenna had to be "dead centre" to plane for it to work properly ?


dit dah  dit dah  dit dah dit dah dit dah dit dah       dit dah dit dah  dit dah dit dah  dit dah dit dah  dit dah  dit dah

   10     20     30    40    50    60    70    80    90   100   110   120   130   140   150   160   170   180   190   200   210   220   230   240

What do you think the bearing is?

gl
Logged

Tom Swearengen

  • T5
  • *****
  • Posts: 818
  • earhart monument, Hawaii
Re: News July 9 1937
« Reply #77 on: February 15, 2012, 07:20:46 AM »

ok---I'm going to give myself another certificate for being crazy----
now if YOU were going to fly 1/2 way across the pacific, and radio communication was paramount to your survival, wouldnt you be more prepared? Its almost like her complacency was on purpose. Arrogant, maybe, purposeful, maybe too. What if----all those naysayers that said she got herslf 'lost' to enable the Navy to do a search was 1/2 true? She could have figured that she would be found and everything would be ok, after a search of the Gilberts and Marshalls was done. That theory doesnt work either, because she had no provisions for hanging out on Niku for several weeks. Maybe that plan fell apart when Fred was injured in the landing.  Another mystery inside a mystery inside another mystery---
Tom Swearengen TIGHAR # 3297
 
Logged

C.W. Herndon

  • T5
  • *****
  • Posts: 634
Re: News July 9 1937
« Reply #78 on: February 15, 2012, 08:30:35 AM »


For you younger guys who have only flown with the newer ADF's with digital tuners, when I started flying the ADF's had what was called a "coffee grinder" tuner. You had to manually tune in and identify the station using the sense antenna and switch to the loop when you were close enough for the loop to work. Great fun.
Do you remember "whistle stop" tuning on your Superhomer?

I never had to do that myself but I remember my uncle doing it while I was flying with him.

gl
Woody (former 3316R)
"the watcher"
 
Logged

C.W. Herndon

  • T5
  • *****
  • Posts: 634
Re: News July 9 1937
« Reply #79 on: February 15, 2012, 09:07:31 AM »

Gary, I am still trying to figure out this system. As I was trying to say, while I never used the civilian model you listed here I did use the same type system in Army flight school when we trained in the L-19. By the time I got out to regular units the comm sets were digital but the old type ADF's stayed around for many more years.
Woody (former 3316R)
"the watcher"
 
« Last Edit: February 15, 2012, 09:12:29 AM by Clarence W. Herndon »
Logged

C.W. Herndon

  • T5
  • *****
  • Posts: 634
Re: News July 9 1937
« Reply #80 on: February 15, 2012, 09:41:17 AM »

And neither [RDF or ADF] will indicate whether you are going toward or away from the station without the "sense antenna".
This comes up all the time, the erroneous idea that you can't resolve the "180 degree ambiguity" without a sense antenna. You can, it is easy, and every pilot knows how to do it. Let's say Earhart has been traveling directly towards Howland and listening for the "A's" (dit dah,  dit dah,  dit dah......) from Itasca. She is now about 200 NM from Howland according to Noonan's dead reckoning, about 1730 Z. She starts to hear them but they are still to weak for her to get a minimum. Now it is 1745 Z and the signal is loud enough for her to get a minimum. She gets two minimums, one with the loop indicator 20° to the right of the nose and the second one at 20° to the left of the tail. Which is the correct bearing? Well, duh, the one in front of the plane is the only possible correct bearing because for the bearing behind the plane to be correct they would have had to have sneaked past the Itasca without hearing anything. The DR shows them approximately 170 NM short of the Itasca so we know this isn't the case so, for this scenario, there is no ambiguity to resolve. So just turn 20° to the right, the bearing is then right on the nose and you are on your way directly towards the Itasca. This is the most likely scenario for Earhart's approach to Howland.

But what if when you first get a null, the bearings are straight out to the side, over the wingtips? Then you do have an ambiguity since you might have missed the island either to the right or to the left so either bearing could be the correct one. Oh! what to do?

It's simple, just continue straight ahead. The bearings will change and the correct one will swing towards the tail. The incorrect one will swing towards the nose. Here is an analogy that might help you remember this. Let's say you are driving your car down the street and you see a really hot chick standing on the sidewalk on the other side of the street, about 45° degrees to your left. Which way does you head swing to follow her as you drive by? It swings counterclockwise, to the left, towards her tail.

If the original bearing is somewhere in between then just turn the plane to place the bearings over the wingtips, hold that heading for a few minutes and look for the one that swings towards the tail.

gl
Gary, your explanation is right on as usual. The web site that I qouted for Harry, http://en.wikipedia.org/wiki/Radio_navigation, when combined with the references it lists, gives a fairly good explanation of how the low freq nav systems worked.
Woody (former 3316R)
"the watcher"
 
Logged

Harry Howe, Jr.

  • T5
  • *****
  • Posts: 576
  • Nuclear Physicist(Ret) Pilot(Ret) Scuba(Ret)
Re: News July 9 1937
« Reply #81 on: February 15, 2012, 11:31:02 AM »


Tom
May I borrow your "Crazy "certificate?   hehe

Might her problem have been arrogance and plain old every day stupidity?
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
Logged

Gary LaPook

  • T5
  • *****
  • Posts: 1624
Re: News July 9 1937
« Reply #82 on: February 15, 2012, 10:37:46 PM »

And neither [RDF or ADF] will indicate whether you are going toward or away from the station without the "sense antenna".
This comes up all the time, the erroneous idea that you can't resolve the "180 degree ambiguity" without a sense antenna. You can, it is easy, and every pilot knows how to do it.
gl
Also see:

https://tighar.org/smf/index.php/topic,555.msg9587.html#msg9587

https://tighar.org/smf/index.php?action=dlattach;topic=555.0;attach=1391

gl

Logged

C.W. Herndon

  • T5
  • *****
  • Posts: 634
Re: News July 9 1937
« Reply #83 on: February 16, 2012, 08:37:37 AM »

Both good reads and I agree with you about Hooven.
Woody (former 3316R)
"the watcher"
 
Logged

Harry Howe, Jr.

  • T5
  • *****
  • Posts: 576
  • Nuclear Physicist(Ret) Pilot(Ret) Scuba(Ret)
Re: News July 9 1937
« Reply #84 on: February 16, 2012, 10:34:48 AM »


Richie
You tune your RDF to the frequency of the "Beacon", you identify by its identifier signal that it is the desired station, you listen for a signal and rotate the loop antenna ( doesn't matter which direction) until the signal stops (the null point), you read the needle on the direction card in the cockpit and "fly the needle"  i.e turn the plane in the direction that the needle is pointing relative to the nose position (the nose position is 0).  When a null is reached and the needle points to 0 then ya know the station is directly on your nose.  Fly in that direction until ya see the island.
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
Logged

Harry Howe, Jr.

  • T5
  • *****
  • Posts: 576
  • Nuclear Physicist(Ret) Pilot(Ret) Scuba(Ret)
Re: News July 9 1937
« Reply #85 on: February 16, 2012, 11:19:50 AM »


The proper operation of thr RDF in AE's plane was  critical to sucessfully finding Howland and I find it unbelievable that she would takeoff after she had indications that her RDF wasn't operating properly.  I understand that I am looking at it with hindsight and that, given the other delays for repairs and time calibration of FN's chronometer, their schedule was all akelter and "get homeitis" night have reared its ugly head, but the RDF was their lifeline.
I wonder when during the flight she discovered that it wasn't working ? Perhaps at the time that she reported being 200 miles out and asked that Itasca take a bearing on them?
Really sad, so close.
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
Logged

richie conroy

  • T5
  • *****
  • Posts: 1412
Re: News July 9 1937
« Reply #86 on: February 16, 2012, 03:05:50 PM »

so did Earhart have to rotate her RDF ? and shud the RDF be 0 to nose cone , i only ask because on one off the photo's of lae take off u see Electra about to take off from side view

but the RDF doesn't seem to be aligned to front nose cone looks more turned to left

so just wondered  :)
We are an echo of the past


Member# 416
 
Logged

Harry Howe, Jr.

  • T5
  • *****
  • Posts: 576
  • Nuclear Physicist(Ret) Pilot(Ret) Scuba(Ret)
Re: News July 9 1937
« Reply #87 on: February 16, 2012, 04:20:33 PM »


Richie
Let's say that you are flying North and the RDF "beacon" is coming from NE (45 degrees),  you turn on your RDF and tune it to the frequency of the "beacon".  Wherever the plane of the loop is facing you will hear a signal.  You then rotate thbe loop until the signal disappears (the null).  At that time the loop will be perpendicular to the direction from which the signal is coming and the needle in the cockpit will be pointing at 45 degrees indicating that the station is 45 degrees to the starboard side of your nose.  You turn your plane to the right by 45 degrees and fly that direction.  Then you take another bearing with your RDF (rotating the Loop until you get a null) and this time te null occurs when the needle indicates that the station is on your nose, i.e.  the zero   indication on the rdf card.  You continue flying that heading and checking the RDF reading .
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
Logged

Harry Howe, Jr.

  • T5
  • *****
  • Posts: 576
  • Nuclear Physicist(Ret) Pilot(Ret) Scuba(Ret)
Re: News July 9 1937
« Reply #88 on: February 16, 2012, 04:59:13 PM »


Richie
Modern day DFs are ADFs which stands for Automatic Direction Finder and you don't have to fool around rotating an antenna, its all done for ya.  All ya have ta do is follow the needle on the ADF indicator.  If it points 15 degrees to the right (starboard) ya turn right and watch the needle move towards zero i.e. the nose.  Fly that direction keeping the needle pointing at zero and ya will fly right over the station abtenna.  Then, if ya keep flying in the same direction the needle will move from zero to 180, i.e. the tail cause the station's antenna is behind you.  Easy smeasy.

Now you're a pilot   LOL
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
Logged

Gary LaPook

  • T5
  • *****
  • Posts: 1624
Re: News July 9 1937
« Reply #89 on: February 17, 2012, 12:35:01 AM »



But what if when you first get a null, the bearings are straight out to the side, over the wingtips? Then you do have an ambiguity since you might have missed the island either to the right or to the left so either bearing could be the correct one. Oh! what to do?

It's simple, just continue straight ahead. The bearings will change and the correct one will swing towards the tail. The incorrect one will swing towards the nose. Here is an analogy that might help you remember this. Let's say you are driving your car down the street and you see a really hot chick standing on the sidewalk on the other side of the street, about 45° degrees to your left. Which way does you head swing to follow her as you drive by? It swings counterclockwise, to the left, towards her tail.

If the original bearing is somewhere in between then just turn the plane to place the bearings over the wingtips, hold that heading for a few minutes and look for the one that swings towards the tail.

gl
I have attached a diagram to show how the 180° ambiguity is resolved which is shown on the bottom diagram. The top diagram illustrates something I didn't mention before, that by timing the bearing change you can also determine how far you will then have to fly to get to the transmitter. The formula is:   

   Time to station = 60 x time for bearing change / number of degrees of bearing change.

An easy way to do this is to time the bearing change in seconds and then the answer will come out in minutes because a minute is 60 times one second. For example if it takes 5 minutes (300 seconds) for the bearing to change by 10 degrees then, when you turn to put the needle (null) on the nose, you will arrive at the station in 30 minutes. (5/10 x 60 = 30) or (300/10 = 30)

gl
« Last Edit: February 17, 2012, 12:38:06 AM by Gary LaPook »
Logged
Pages: 1 ... 4 5 [6] 7   Go Up
 

Copyright 2024 by TIGHAR, a non-profit foundation. No portion of the TIGHAR Website may be reproduced by xerographic, photographic, digital or any other means for any purpose. No portion of the TIGHAR Website may be stored in a retrieval system, copied, transmitted or transferred in any form or by any means, whether electronic, mechanical, digital, photographic, magnetic or otherwise, for any purpose without the express, written permission of TIGHAR. All rights reserved.

Contact us at: info@tighar.org • Phone: 610-467-1937 • Membership formwebmaster@tighar.org

Powered by MySQL SMF 2.0.18 | SMF © 2021, Simple Machines Powered by PHP