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Author Topic: Radios for the Second Attempt  (Read 22657 times)

Ric Gillespie

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Radios for the Second Attempt
« on: January 08, 2016, 10:42:37 AM »

As part of the research for the new Electra book, Bob Brandenburg and I have been trying to pin down how the radio systems aboard NR16020 evolved over time and exactly what radios were present for the second world flight attempt.  It's an important question because Earhart's failure to find Howland was essentially a failure of radio navigation. 

In piecing together what happened we've uncovered another mystery and I'm hoping the Forum can help us.  Here's a quick overview. (Sorry if this gets a bit down-in-the-weeds but there's no avoiding the technical aspects of the problem.)

In Burbank, on or about March 7, 1937 as NR16020 was being prepared for a planned March 15 departure from Oakland, the Hooven Radio Compass (installed back in October) was removed and replaced with a Bendix loop, loop coupler, and receiver.  The loop and loop coupler appear to have been a Navy RDF-1 system and the receiver seems to have been an early version of the RA-1.  This new receiver was installed on top of the fuel tanks behind the cockpit bulkhead behind the copilot - the same location where the Hooven receiver had been situated.

One advantage of the new receiver was that it covered 500 kHz, the marine calling and emergency frequency.  The Western Electric 20B receiver under the copilots seat did not include that frequency.  In February, W.C. Tinus at Bell Labs had convinced Earhart that it would be good if she could communicate with ships on 500 kHz and he had modified her Western Electric 13C transmitter to include a 500 kHz crystal.  500 kHz requires a long antenna and the airplane was equipped with a trailing wire for that purpose. 500 kHz is also a code-only frequency but Earhart had Harry Manning aboard as navigator and radio operator.  Manning was adept at Morse code.
With the new receiver Manning would have two-way communication in code with ships at sea.
Helping Earhart with radio matters at this time was United Airlines technician Joe Gurr.  Gurr later said that he helped Manning learn how to use the Bendix DF system but had little luck getting Earhart to pay attention long enough to really become familiar with it.

Manning left the team after the accident at Luke Field.   Gurr later said that he reinstalled the radios in early May while the plane was in the Lockheed repair shop.  Gurr was under the impression that the plane had the same radios aboard for the second world flight attempt as for the first.  Based primarily on Gurr, Elgen Long was quite sure there was a Bendix receiver aboard for the second attempt. That does not seem to be the case. In the time between when Gurr reinstalled the radios in early May and when the plane came out of the shop on May 19 the Bendix receiver was apparently removed and the loop and loop coupler were attached to the Western Electric 20B receiver. There are two sources to support this conclusion:

1.  A statement made by Chicago Tribune reporter and Earhart friend Carl B. Allen in a manuscript reportedly now in the Smithsonian National Air & Space Museum archives.  The following is from East to the Dawn - the Life of Amelia Earhart by Susan Butler (page 387):
"When Allen first arrived in Miami and caught up with Amelia at the airport, one of the first things he did was to go over the equipment list to see if there had been any changes since Oakland. he noted one change that he was;t sure he approved of - the elimination of the marine frequency radio that operated on the 500-kilocycle bandwidth.  “Oh,” she said, ‘that was left off when Manning had to drop out of the flight. Both Fred Noonan and I know Morse code but we’re amateurs and probably would never be able to send and receive more than 10 words a minute …The marine frequency radio would have been just that much more dead weight to carry and we decided to leave it in California.”
This is an extremely important quote and I want to check the source myself.  I’ve put in a request to NASM to confirm that they have the manuscript and whether it’s at the Udvar-Hazy archives at Dulles or at the NASM Library downtown.

2. In "Last Flight, chapter titled Karachi, Earhart described the "Bendix direction finder" as an instrument on her "dash."  She says the Western Electric receiver is under the copilots seat.  No mention of a separate Bendix receiver. In fact, nowhere in the 1937 literature (Earhart, Chater, etc.) does anyone say anything about a Bendix receiver.

The mystery is who made the changes in those last days before the plane left the Lockheed shop? 

 As an aside, there is a rather strange quote via Fred Goerner:
"Lieutenant Commander William Van Dusen, U.S. Naval Reserve (ret.) (who worked with Pan American Airways for many years) has written, "The simple reason ships and shore stations were unable to communicate with the Earhart plane or to transmit bearings, is that the radio transmitter for these marine frequencies was left sitting in the corner of a hangar in Miami when Earhart and Noonan left the U.S.  At the last minute she decided to leave it behind because it weighed so much: it meant more work paying out and reeling in an aerial line."

It's not clear where Goerner got this. The Bendix radio was a receiver not a transmitter. This may have been the start of the myth that the trailing wire was removed in Miami.  Photos of the plane in Burbank prior to departing for Miami clearly show that the trailing wire was already gone.
« Last Edit: January 08, 2016, 10:47:14 AM by Ric Gillespie »
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Martin X. Moleski, SJ

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Re: Radios for the Second Attempt
« Reply #1 on: January 08, 2016, 11:18:16 AM »

Photos of the plane in Burbank prior to departing for Miami clearly show that the trailing wire was already gone.


It's amazing how much can be discovered after all these years!


Looking forward to the new book.   :)
LTM,

           Marty
           TIGHAR #2359A
 
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tom howard

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Re: Radios for the Second Attempt
« Reply #2 on: January 11, 2016, 04:47:28 AM »

It is not too much of leap to conclude losing Manning killed Earhart.
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Ric Gillespie

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Re: Radios for the Second Attempt
« Reply #3 on: January 11, 2016, 04:38:45 PM »

It is not too much of leap to conclude losing Manning killed Earhart.

If we're looking for root causes of the tragedy i think we have to start further back. Manning bailed because he lost faith in Earhart's ability to safely operate the airplane. The Luke Field accident had nothing to do with radios.  Perhaps the root cause is the simple fact that Earhart was in over her head, as was her habit throughout her flying career, and this time her incredible run of luck ran out.
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Dale O. Beethe

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Re: Radios for the Second Attempt
« Reply #4 on: January 11, 2016, 05:36:35 PM »

Thank you!  That's been my opinion for years now (after reading a lot of the content of your site), but it's not a popular one on many fronts. 
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Ric Gillespie

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Re: Radios for the Second Attempt
« Reply #5 on: January 12, 2016, 09:03:06 AM »

This just in:

"This is on file in the NASM Archives and is known as:
Amelia Earhart Collection [Allen], Acc. XXXX-0520
Dates: 1932-1971
Description: Carl B. Allen learned to fly during World War I.  He was active in aviation events and as an aviation writer.  Allen was the first airmail passenger to make a continuous flight across the continent in 1927 and he made an air tour of South America in 1933.  He won the Sportsman Pilots' cup at the National Air Races in 1930.  Allen was the aviation editor of several newspapers, including the New York Herald-Tribune, and he wrote several aviation books, including 'ghosting' Clarence Chamberlin's 'Record Flights.'  He was also a flight advisor to Amelia Earhart. 
This collection consists of correspondence and writings of Mr. C. B. Allen on the disappearance of Amelia Earhart."

Somehow we missed this source.  I'll be making a pilgrimage to Udvar-Hazy Center NASM Archives to review the collection for any new nuggets.
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Leslie G Kinney

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Re: Radios for the Second Attempt
« Reply #6 on: January 13, 2016, 08:43:33 PM »

and archived at NASM
This just in:

"This is on file in the NASM Archives and is known as:
Amelia Earhart Collection [Allen], Acc. XXXX-0520
Dates: 1932-1971
Description: Carl B. Allen learned to fly during World War I.  He was active in aviation events and as an aviation writer.  Allen was the first airmail passenger to make a continuous flight across the continent in 1927 and he made an air tour of South America in 1933.  He won the Sportsman Pilots' cup at the National Air Races in 1930.  Allen was the aviation editor of several newspapers, including the New York Herald-Tribune, and he wrote several aviation books, including 'ghosting' Clarence Chamberlin's 'Record Flights.'  He was also a flight advisor to Amelia Earhart. 
This collection consists of correspondence and writings of Mr. C. B. Allen on the disappearance of Amelia Earhart."

Somehow we missed this source.  I'll be making a pilgrimage to Udvar-Hazy Center NASM Archives to review the collection for any new nuggets.

I have copied all the Allen material; however, much of the "good stuff" Allen memorialized and found at the Smithsonian can also be found in:  Amelia Earhart: A Biography, by Doris Rich, Smithsonian Institution Press 1989. 
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Ric Gillespie

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Re: Radios for the Second Attempt
« Reply #7 on: January 14, 2016, 03:59:07 PM »

I have copied all the Allen material; however, much of the "good stuff" Allen memorialized and found at the Smithsonian can also be found in:  Amelia Earhart: A Biography, by Doris Rich, Smithsonian Institution Press 1989.

Rich's book is poorly footnoted and contains many errors. 
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Ted G Campbell

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Re: Radios for the Second Attempt
« Reply #8 on: January 30, 2016, 08:02:37 PM »

Ric,

Re the current subject;  I have come to the conclusion by reading past posts on the subject of radios that AE’s final flight had the Western Electric radio as the transmitter radio – is that correct?

Also, I’ve seen pics of the 10E’s panel that shows radio controls that indicate:

MIC on/off and TRANS on/off

Would the following combinations give the results suggested?

   MIC on, TRANS off – for intercom purposes without broadcasting outside the aircraft

   MIC on, TRANS on – both intercom on and transmission outside the aircraft

Would these switch combinations take the place of a “push-to-talk” mic configuration we use today i.e. when in the Mic on/Trans on you end up with an open mic with no finger pressing a button necessary?

Ted Campbell
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Ric Gillespie

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Re: Radios for the Second Attempt
« Reply #9 on: January 31, 2016, 07:30:16 AM »

Re the current subject;  I have come to the conclusion by reading past posts on the subject of radios that AE’s final flight had the Western Electric radio as the transmitter radio – is that correct?

That is correct.  I don't think anybody disputes that.

Also, I’ve seen pics of the 10E’s panel that shows radio controls that indicate:

MIC on/off and TRANS on/off

Would the following combinations give the results suggested?

   MIC on, TRANS off – for intercom purposes without broadcasting outside the aircraft

   MIC on, TRANS on – both intercom on and transmission outside the aircraft

Would these switch combinations take the place of a “push-to-talk” mic configuration we use today i.e. when in the Mic on/Trans on you end up with an open mic with no finger pressing a button necessary?

I agree that MIKE (sic)/on, TRANS/on might create an "open mic", but if the plane had intercom capability why did AE and FN communicate by means of written notes?
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Ric Gillespie

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Re: Radios for the Second Attempt
« Reply #10 on: February 04, 2016, 09:16:06 AM »

Ted Campbell's query about the radio panel got me wondering whether that panel was standard for Model 10s or unique to NR16020.   Digging back through the records, I discovered that we have an engineering drawing for that panel (see below) Drawing Number 42690.  I got it in 2004 from the guys in the restoration shop at the National Museum of Naval Aviation in Pensacola.  At that time they were working on finishing the rebuild of Electra c/n 1130 as a replica of NR16020 but the museum abandoned that project and the rebuild was completed as a sort-of replica of the Electra the Navy had as a VIP transport.  (The actual Navy airplane is c/n 1052 at the New England Air Museum which has been rebuilt as as Northwest Airways airliner - go figure.)
Anyway, looking through the lists of Lockheed engineering drawings for the Model 10 - both the NASM microfilm and the Lockheed Maintenance Parts Catalog - there is no Part Number 42690.  I have no idea where Pensacola got the drawing they gave me but it is clearly the same control panel shown in photos of the NR16020 cockpit.  There is no reference to c/n 1055 on the drawing but the drawing was made on July 15, 1936.  That's exactly when c/n 1055 was being completed prior to delivery.  This looks very much like something that was done specifically for Earhart at her request.
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Patrick Dickson

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Re: Radios for the Second Attempt
« Reply #11 on: February 04, 2016, 11:51:18 AM »


Quote
[Anyway, looking through the lists of Lockheed engineering drawings for the Model 10 - both the NASM microfilm and the Lockheed Maintenance Parts Catalog - there is no Part Number 42690./quote]
 
Ric,
 
In aircraft mfg., is the Lockheed part number always associated with the engineering drawing number ??
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Ric Gillespie

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Re: Radios for the Second Attempt
« Reply #12 on: February 04, 2016, 12:40:21 PM »

In aircraft mfg., is the Lockheed part number always associated with the engineering drawing number ??

The part number IS the drawing number.
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Ric Gillespie

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Re: Radios for the Second Attempt
« Reply #13 on: February 08, 2016, 09:08:10 AM »

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Daniel R. Brown

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Re: Radios for the Second Attempt
« Reply #14 on: June 03, 2016, 01:23:10 PM »

In support of the "second receiver" theory, the response to C.B. Allen's concerns about marine frequency reception may explain these otherwise anomalous Associated Press reports:

“EARHART IN MIAMI ON TEST FLIGHT: Radio Direction Finder Installed in Plane”. [Dateline 5/23/37 Miami FL] “Pan-American Airways loaned her two technicians to install in her plane a radio direction finder similar to those used in South American and Pacific flights.” Source: 5/24/37 Atlanta Constitution

“A radio direction finder has been installed by Pan American technicians.” Source: 5/30/37 New York Times

“Their own mechanics installed the radio direction finder which they developed for their clipper ships…” Source: 6/1/37 New York Times

The standard receiver used in PAA Clippers was "distinguished by its wide frequency range (250 kc to 25 mc), its light weight (6 pounds) and its simplicity of design...". The Clippers were equipped with crossed-loop DF antennas. Source: "Flying the Pacific by Radio" April, 1936 Electronics, p. 7-10.

The Bendix RA-1B receiver weighed 25 pounds. Source: Instruction Book for Models RA-1B, RA-1I and RA-1J Aircraft Radio Receiving Equipment. Bendix Radio, 1941.

But, GP still referred to the DF as a "Bendix beam-finder" in a late June interview. Source: 6/26/37 Atlanta Constitution (United Press)

FWIW

Dan Brown, #2408
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