TIGHAR
Amelia Earhart Search Forum => General discussion => Topic started by: Ric Gillespie on April 03, 2020, 12:03:16 PM
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An email from Forum observer David Land in Scotland raises an interesting possibility.
"Re the question of WE 20B coverage of KGMB on 1320 kHz, since the IF frequency is 96 kHz, if the receiver is tuned to 1128 kHz, within its possible Band 2, KGMB would be on the image frequency. There might be an adequate response to hear a signal. (Earlier Tighar analysis of Electra radio equipment.)
However Earhart and / or Noonan would have had to reconnect the transmitter-to-WE 20B link to enable the dorsal antenna. The cable might have been left in-situ when the Hooven equipment was removed.
Night-time sky-wave reception of KGMB at Gardner Island might then have been possible."
I'm not familiar with "image frequency" so I can't comment on that part, but it's true that the dorsal vee antenna could serve dual purpose for transmitting and receiving through terminals on the WE 13C transmitter. We've been assuming that, since the belly wire receiving antenna was lost on takeoff from Lae, any reception of signals from then on (the "A"s on 7500 heard in-flight and any post-loss receptions) were heard via the loop antenna.
Is there any chance Earhart and/or Noonan could have connected the receiver to the dorsal vee?
First, they would have to know enough to try.
Second, there would have to be a cable and connectors laying around they could use. It seems to me like the only way that would be possible is if the dorsal vee had, at some point, been connected to the receiver via the transmitter.
That doesn't seem to be the case. Both the Hooven Radio Compass and the Bendix RDF used a "sense antenna" to resolve the 180° ambiguity. This was a belly wire antenna that ran down the port side of the belly parallel to the belly wire on the starboard side. (See illustration below.)
A photo taken in the cabin some time between October 1936 when the Hooven Radio Compass was installed and March 1937 when it was removed, shows no cable connected to the receiver terminal on the transmitter. So, at least at that time, the dorsal vee was being used only for transmitting. (see photo)
The lead-in for the starboard-side belly antenna was under the nose directly below the WE20B receiver (see photo).
There was another lead-in aft that appears to be more or less on the centerline between the two belly antennas and under the transmitter, but it's not clear which antenna it's connected to. (see photo) The starboard antenna lead-in is in the nose, so the aft lead-in must be to the sense antenna. It wouldn't make any sense for the sense antenna to be plugged into the transmitter so there must have been a long cable connecting it to the Hooven, and later Bendix, receiver on top of the fuel tank forward. The sense antenna and Bendix receiver were not re-installed when the plane was repaired after the Luke Field wreck. I suppose it's possible the long connecting cable was still in the airplane during the second world flight attempt but it wouldn't be long enough to reach from the WE20B to the receiver terminal on the transmitter.
NOTE: The belly antenna illustration below is wrong. See posting on 4-5-20 for correction.)
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I'm not familiar with "image frequency" so I can't comment on that part,
But Bob Brandenburg can.
"The WE 20B design precluded the problem David Land raised re image frequency. .
The image frequency is plus or minus twice the intermediate frequency (IF). If there is insufficient selectivity prior to the input of the receiver mixer stage (where incoming RF signals are converted to the IF), then two signals from stations on frequencies spaced at twice the IF could get through to the subsequent amplifier stages, interfering with each other. This selectivity problem is avoided in receiver design by including a tuned RF amplifier stage prior to the mixer stage, as was the case with the 20B."
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Ric, thanks so much for this post and the very helpful diagram and photos with labels. The radio gear on the Second Try has for some time been my favorite AE briar patch.
Two queries that may or may not prove relevant:
1. In the diagram of the belly, shouldn’t the position of the Hooven or Bendix DF receiver be shown on the starboard side (not port), and shouldn’t it be a few feet aft of the WE 20B receiver position under the copilot’s seat, to allow for the space occupied by the bulkhead and the R1 tall fuel tank? This will be relevant to the question you asked, whether the long connecting cable that during the First Try ran from the sense antenna to the DF receiver, IF it was still in the plane during the Second Try, might have been repurposed to run from the transmitter antenna post to the WE 20B receiver under the copilot seat. That is, can we estimate the minimum length of that long connecting cable?
2. On the Second Try, what was the location of the cabin entry-point of the lead-in from the dorsal Vee antenna? Yes, the Hooven-era cabin photo you posted shows it clearly, where it no doubt still was for the First Try in March. But for the Second Try the dorsal Vee was lengthened and its forward mast moved forward, close enough to where the Hooven dorsal faired loop was located, that it makes me wonder if the lengthened dorsal Vee lead-in might have entered the cabin about where you note the Hooven dorsal antenna in the photo. But the question here is not so much that cabin entry point, I guess, but whether, once landed on Niku, they could have reached the dorsal Vee antenna from the open hatch over the pilot seat, in order to run a wire directly from the dorsal Vee in to the WE 20B receiver, through the open hatch?
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The transmitters and receivers of the 1930's and most of WWII did not use coax (a controlled impedance transmission line with shield) or any of the special connectors involved. Coax in aircraft radio use really didn't happen until late WWII with radar and IFF transceivers like the BC-645 operating in the VHF/UHF frequencies.
Instead, the lead-in wire for the transmitter or the receiver would have been no more than a well insulated wire without a shield. In the photo you show on the aircraft interior and transmitter, the antenna connections to the WE transmitter are the white ceramic 'bee-hive' insulators just visible. The connection to these is a push-insert-bare-ware connection that requires no tools. I verified this by finding a picture of the WE 13C on the web.
I didn't find a picture of the antenna connection on the WE 20B receiver, but most likely it's the same type of bare wire connector. Receivers of the era had high-impedance inputs, and a piece of wire was sufficient for quick use. The bigger the antenna, the better. I've used these old short-wave receivers with no more than the hook of a coat-hanger straightened and poked into the receiver terminal.
Looking at WWII RDF loops (on ebay) they seem to use circular connectors with several pins, probably to connect to the several windings inside the RDF loop for phasing.
So, if Amelia and Fred needed to change around antenna connections at Gardner, all they would have needed is wire, or several lengths of wire, ends twisted together, connecting to the antenna lead-in with no special connections. Wire could have been removed from anywhere in the aircraft wiring if it was not among their spare parts.
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1. In the diagram of the belly, shouldn’t the position of the Hooven or Bendix DF receiver be shown on the starboard side (not port), and shouldn’t it be a few feet aft of the WE 20B receiver position under the copilot’s seat, to allow for the space occupied by the bulkhead and the R1 tall fuel tank? This will be relevant to the question you asked, whether the long connecting cable that during the First Try ran from the sense antenna to the DF receiver, IF it was still in the plane during the Second Try, might have been repurposed to run from the transmitter antenna post to the WE 20B receiver under the copilot seat. That is, can we estimate the minimum length of that long connecting cable?
Thanks Bill. You're absolutely right. Corrected illustration below.
2. On the Second Try, what was the location of the cabin entry-point of the lead-in from the dorsal Vee antenna?
When the mast for the dorsal vee was moved forward by Joe Gurr in Burbank, the lead-in point was moved down on the cabin wall, effectively further lengthening the total antenna length supposedly to give the aircraft some ability to transmit on 500 kHz after the trailing wire was eliminated. All it accomplished was to screw up the other two frequencies. In Miami, Pan Am was apparently able to improve 3105 and 6210 somewhat by adding a "loading coil" but there was no meaningful propagation on 500 kHz.
But the question here is not so much that cabin entry point, I guess, but whether, once landed on Niku, they could have reached the dorsal Vee antenna from the open hatch over the pilot seat, in order to run a wire directly from the dorsal Vee in to the WE 20B receiver, through the open hatch?
No problem. See photo below.
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Instead, the lead-in wire for the transmitter or the receiver would have been no more than a well insulated wire without a shield. ...
So, if Amelia and Fred needed to change around antenna connections at Gardner, all they would have needed is wire, or several lengths of wire, ends twisted together, connecting to the antenna lead-in with no special connections. Wire could have been removed from anywhere in the aircraft wiring if it was not among their spare parts.
When we first found Artifact 2-2-V-1, there was a length of insulated wire jammed in a tear in the metal. The NTSB Lab examined the wire and found:
"The wire was a single strand of 0.024 inch diameter copper wire that was 34 inches long. Remnants of what appeared to be degraded and hardened insulation were found randomly along the the length of the wire. Examinination of a portion of the insulation with the aid of a scanning electron microscope (SEM) revealed fibrous strands, encased in the insulation jacket as denoted by arrow "T" in figure 11B.
Samples of reportedly common aircraft antenna wire labeled "1938" and "1941" were also supplied by the investigator for comparison purposes and displayed in figure 11C. The "1938" wire sample had a single strand, solid wire core with an easily fragmented inner insulation and a woven fabric outer covering. EDXA analysis determined that the copper wire core had been tinned prior to being insulated. The inner insulation had two longitudinal fibrous threads, arrowed "T1" in figure 11C, embedded within the insulation material. The wire small labeled "1941" had a similar outer covering but in contrast had a multiple strand twisted wire core and a rubbery inner insulation with no indications of imbedded threads."
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Think about this for a second. If the wire entangled on 2-2-V-1 is, indeed, aircraft antenna wire vintage circa 1938, where did it come from (regardless of whether or not 2-2-V-1 is the patch)? As a stand-alone artifact it's pretty interesting and potentially extremely important. Could this hunk of wire be merely garden-variety British electrical wire?
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I suppose it could be but how likely is it something likely of value to the colonists, even if no longer usable as an antenna lead or other electrical use, would be discarded in such a manner, even up to the time the colony was evacuated, that it could become hung up in 2-2-V-1? I guess we'll need to find examples of British wire from the mid-30's to the mid 60's.
(added Monday AM)
It could have come from the Norwich City as well but that would require quite a mixing of debris over the years.
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Ric...in regards to what you guys have been discussing about...I have a question..and it merely relates to the Norwich City. Now, I was never there some 20 years ago when you had your first expedition. But, do you think it was possible if Amelia had the means to use the Norwich City radio if she could. Again, I dont know the status condition of the ship after the fire. I would love to believe that some part of the ship was salvageable. But, it makes me wonder if Fred and Amelia didnt attempt to get on the ship somehow to get access to a better radio, or more batteries.
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But, do you think it was possible if Amelia had the means to use the Norwich City radio if she could. Again, I dont know the status condition of the ship after the fire.
In 1937 Norwich City was a burned out hulk. I don't think there is any chance the radio was usable. Even if it was, Norwich City communicated only in code. Neither Earhart nor Noonan knew Morse code.
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When the mast for the dorsal vee was moved forward by Joe Gurr in Burbank, the lead-in point was moved down on the cabin wall, effectively further lengthening the total antenna length supposedly to give the aircraft some ability to transmit on 500 kHz after the trailing wire was eliminated.
Earhart researcher and Forum observer Les Kinney sent me the snapshot below of a May 5, 1937 letter from Joe Gurr to Paul Mantz.
Lots there to digest. Repairs were completed and the airplane was inspected on May 19, so the the letter dates from two weeks earlier. It's Gurr's recommendation about what should be done, not a report of what was actually done.
We also have the following excerpt from a letter Gurr wrote to Fred Goerner in 1970.
"On the take off at Honolulu, with Amelia, Harry Manning and Fred Noonan aboard on their next leg to Howland Island the landing gear folded and the airplane ended up in a ground loop. The damaged plane was shipped back to Lockheed at Burbank for repair. I was called in regarding the radio installation, as everything had to be removed. I took the whole installation home. My job was to make sure that the equipment was not damaged, I took everything apart and checked completely. There were some repairs and adjustments made which I am sure were not required because of the accident, but nothing serious. I worked the transmitter into a dummy antenna and it put out a good signal. While the airplane was being repaired at Lockheed, I took the opportunity to redesign the top antenna. This required a new stub mast on top of the fuselage, behind the cockpit, with a wire to each rudder, and a lead-in from one side to an insulator in the fuselage. The antenna looked similar as before, but now we had about 50% more wire. It made a great deal of difference in radiated energy. Also, because of the added wire, this top antenna now would be more effective on 500KH. I made a loading coil. and tuned it for maximum output. It was still not much under the circumstances but it got out and Amelia was pleased. We designed a belly sensing antenna for preliminary reception of signals to be used for direction finding. I left the reel antenna on board, and it could have been used. Harry Manning knew how to switch it in if necessary. This work was done at Lockheed. However, Captain Harry Manning's leave of absence would now run out before Amelia could make her flight, so he bowed out and returned to Washington."
In his 1970 letter, Gurr says the belly antenna was a sense antenna for the direction finder. Could the belly antenna be used as both a receiving antenna for voice and a sense antenna for the DF?
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Could this hunk of wire be merely garden-variety British electrical wire?
Forum observer Dan Cotts writes:
"If that wire is 0.024 inches in diameter then there is no way it could carry
any appreciable amperage. So would not be used in any household electrical
system. Seems to me something like that would be used in communications or
control circuits."
We also have this from Norman Chipps of Chipps Research, an expert in aircraft radio history, in a letter to TIGHAR dated January 31, 1992.
"In most cases the [antenna] wire, until later days, was a heavy rubber and varnished cotton covered small gauge conductor which was very flexible. The fairlead wire (wire inside of the aircraft to connect receivers to antennas ) was a small conductor cable with smaller diameter cloth and rubber covering.
The 22 gauge wire you have found entangled in artifact 2-2-V-1 could possibly be from the external lead or the internal fairlead. Normally electrical lighting wiring and electrical appliance wiring is supported every 6 to 18 inches but the wire you have has no evidence of mounting brackets unless it had been earlier removed by a person in need of a piece of wire or a salvor trying to recover usable items from a wrecked aircraft."
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Here's a puzzle.
We have two photos that show the front of the 13C transmitter. In the first photo below, we can see there is nothing attached to the receiver terminal, indicating the dorsal vee is not being used to receive.
In the second photo below, the terminals are hidden behind AE's right leg, but what's the connection at "A" going down through the floor? Also, what are the features at "B" and "C" that are not present in the previous photo? The date for the photo is unknown but it was taken before the navigator's table was installed.
The third photo was taken March 12, 1937. The navigator's table has been installed (you can see the "goose neck" of the lamp) but features "B" and "C" are no longer present. Also, the fuel tank vent line manifold "D" has been wrapped with wire(?) and there's a bundle of wire or cable "E" running to either the transmitter or the aft battery.
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Feature A appears to not have an insulator but looks more like a cylindrical, push-button connector or a knurled nut/post, both of which I've seen on older radio gear. Could it be the chassis grounding connection to a welded lug on the keel of the Electra?
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Several days ago I wrote Ron Hashiro of Hawaii an email in regards to an article he wrote on radio history in Hawaii. He wrote me back and it was quite interesting. Thought this might help...
If I may suggest, contacting KSSK radio in Honolulu, which is the successor to KGMB.
Supposedly at the time of Amelia Earhart, KGMB was in the 1300's kHz. The other station was KGU-AM 760 kHz, which was located in the then Honolulu Advertiser building on Kapiolani Blvd and South Street. Because the 760 kHz frequency was also used on the West Coat, KGU-AM had to vacate that frequency at night in order to not interfere with the West Coast.
I know the 590 kHz AM tower was on 1710 (?) Ala Wai Blvd, and is since long gone. The AM facilities have moved to a "new" tower next to Kapalama Canal. I'm guessing it was the tower on Ala Wai Blvd (it may have been elsewhere) that did the work. I know up until the 70's, that the RCA 1D transmitter (the one used on the day of Pearl Harbor) was housed there. The entire building has since been vacated of radio equipment.
additional information...
https://www.qsl.net/ah6rh/am-radio/hawaii/history.html
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Could it be the chassis grounding connection to a welded lug on the keel of the Electra?
A grounding connection would be my guess.
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The three photos (on the previous page of this thread) show a number of differences.
Photo 1: Lead-in for dorsal antenna is high in the fuselage cabin. In this photo we can see the first stand-off support for the lead in, but it may be a different style standoff from what is in Photo 2. For the antenna, the stand-off supports would have been important as the antenna lead-in has no shielding, and you don't want close nearby metal to affect your antenna coupling and you want to control where the lead-in wire is so it doesn't move about and affect the pre-fixed tuning of the transmitter (i.e. you want to control the parasitic capacitance to ground). Transmitter tuning did not involve maximum signal into the antenna, but minimum signal reflected back into the transmitter. Too much signal reflected back into the transmitter results in heating of the output power tube.
Photo 2: We do not see the lead-in entry. We do see the lead-in as it goes vertical on the sidewall. The lead in is supported by ceramic standoffs (a proper installation practice). In photo 2 we do not see the ends of the 1"x 1" wood supports for the fuel tank crawl-over platform (that should be near the arrow of C and visible in photo 3). So photo 2 may be prior to a crawl over being installed. Does the 'pipe?' in C represent a different fuel-tank vent setup? (I assume those are the tank vent tubes) Feature A on the WE 13C Transmitter is definitely an antenna ground connection. It can be seen in this photo of another WE 13C. https://kn4r.com/kn4r/Western_Electric_13-C.html And the ground connection for the antennas shows up on the schematics. https://aafradio.org/docs/Western_Electric_WE_13C_Transmitter.pdf
Photo 3: With D it appears that a wire harness is now running along the fuel vent manifold, and tied-down with a wax lacing cord?/wire loom method. As the cable comes to the end of the vent manifold, it goes down the cabin wall - indicated with arrow E. but at E an additional black cable can be seen. Is this the antenna lead-in? That would explain the shielding added to the cable. Shielding the harness would be necessary to keep antenna RF from coupling into the wiring and creating issues elsewhere in the aircraft. Also, the point at where the lead-in exits through the cabin wall cannot be as high as it was in Photo 1, so Photo 1 and photo 3 must have had different antenna arrangements.
Frankly, if I have interpreted photo 3 correctly, the lead-in laced directly to a shielded harness looks to be poor installation practice for this kind of open-wire line. I'm not familiar with acceptable signal and transmission line integrity practices of the 1930's. Close proximity results in a some of your transmitter power shunted somewhere other than the antenna. No doubt that when they did this Photo 3 installation they re-tuned the transmitter output, but that only keeps the transmitter happy.
Since installation manual for a WE 13C Transmitter is not available, I went a aircraft transmitter with similar power output, frequency range, and antenna attachment method. The following is from a installation manual for a military ARC-5 "Command Set" transmitter developed in 1936 and used throughout WWII until the early 1960's. Document: "AN 16-30ARC5-2" Dated Dec 15 1954, Page 9 section 2-6 "Installation" paragraph i. followed by paragraph l.
i. Short antenna leads inside the fuselage are essential. This requires the use of the minimum, practical spacing between the antenna relay unit, the antenna binding posts on the receivers and transmitters, and the antenna lead-in insulator. Bare wire supported on ceramic insulators, where necessary, should be used for all antenna connections. These installations precautions are necessary to minimize voltage breakdown, to reduce r-f losses, and to keep to a low value the capacitance to ground of the antenna wiring inside the fuselage.
l. To accomplish proper grounding of the transmitters, connect a 'short' flexible lead from the aircraft frame to each of the ground binding posts on the rack. ...... Reduced antenna current from the transmitters will result if these precautions are not observed.
You indicate the NTSB lab reported a wire diameter of 0.024". If a precise measurement (neglectable diameter change from corrosion), then this is the exact nominal diameter of 22.5 AWG wire (0.0240"). This is also 0.61mm. Solid magnet wire is available in 1/2 gauge steps in the present era but what about wire in the 1930's?
I used to play with some of the radios back in the 70's when a teenager and actively experimenting amateur radio ham. Today I work as an electrical engineer (designing power inverters for the aviation General Aviation market) but have done a bit of RF work in my career.
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Here are some items I couldn't figure out about the pictures.
What are the two horizontal 'tubes' running along the wall next to Amelia's left knee in photo 2? They are at a level higher than the top of the transmitter in that picture. There is nothing at that height in photo 1. Just a different 'tube' at a lower level (about the level of the lower row of fuel tank rivets of photo 1). I seem to recall something in the history of the Electra that the fuel tanks had to be removed for some kind of work - is that correct? Did they re-arrange some of these less accessible items then? Could these be for control cables for something associated with the navigators table? Didn't the Electra have a boot de-icer on the tail early on, and could this be for that system?
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What are the two horizontal 'tubes' running along the wall next to Amelia's left knee in photo 2? They are at a level higher than the top of the transmitter in that picture. There is nothing at that height in photo 1. Just a different 'tube' at a lower level (about the level of the lower row of fuel tank rivets of photo 1).
The attached illustration shows how Bill Harney drew the interior of the cabin. Bill's 25 years of research were exhaustive, drawing on every photo he could find. He didn't get everything right, but the errors I've found have been minor.
He shows the "tubes" connecting to the auxiliary battery. He also shows the dorsal vee antenna lead-in in its final position low on the cabin wall.
I seem to recall something in the history of the Electra that the fuel tanks had to be removed for some kind of work - is that correct?
That's correct but it was in August 1936 shortly after the plane was delivered.
Didn't the Electra have a boot de-icer on the tail early on, and could this be for that system?
De-icing boots were in the original specs but were never installed.
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The three photos (on the previous page of this thread) show a number of differences.
Photo 1: Lead-in for dorsal antenna is high in the fuselage cabin. In this photo we can see the first stand-off support for the lead in, but it may be a different style standoff from what is in Photo 2. For the antenna, the stand-off supports would have been important as the antenna lead-in has no shielding, and you don't want close nearby metal to affect your antenna coupling and you want to control where the lead-in wire is so it doesn't move about and affect the pre-fixed tuning of the transmitter (i.e. you want to control the parasitic capacitance to ground). Transmitter tuning did not involve maximum signal into the antenna, but minimum signal reflected back into the transmitter. Too much signal reflected back into the transmitter results in heating of the output power tube.
Photo 2: We do not see the lead-in entry. We do see the lead-in as it goes vertical on the sidewall. The lead in is supported by ceramic standoffs (a proper installation practice).
I think we see the same kind of ceramic stand-off in the first photo as we see lower down in the second photo. I don't think the lead-in has changed between the two photos.
In photo 2 we do not see the ends of the 1"x 1" wood supports for the fuel tank crawl-over platform (that should be near the arrow of C and visible in photo 3). So photo 2 may be prior to a crawl over being installed.
I see what you mean. Good catch. So Photo One probably predates Photo Two and they both predate Photo Three.
Does the 'pipe?' in C represent a different fuel-tank vent setup? (I assume those are the tank vent tubes)
Yes, those are tank vent tubes. so it probably does represent a different vent set-up - a further indication that Photo Two predates Photo One.
Photo 3: With D it appears that a wire harness is now running along the fuel vent manifold, and tied-down with a wax lacing cord?/wire loom method. As the cable comes to the end of the vent manifold, it goes down the cabin wall - indicated with arrow E. but at E an additional black cable can be seen. Is this the antenna lead-in?
I don't know what else it would be.
That would explain the shielding added to the cable. Shielding the harness would be necessary to keep antenna RF from coupling into the wiring and creating issues elsewhere in the aircraft. Also, the point at where the lead-in exits through the cabin wall cannot be as high as it was in Photo 1, so Photo 1 and photo 3 must have had different antenna arrangements.
So it would seem, but a photo of the airplane in the hangar at Wheeler Field in Honolulu on March 18 shows the lead-in entry in the location shown in Photos One and Two, and yet we know Photo Three was taken on March 12. I can't explain it.
Frankly, if I have interpreted photo 3 correctly, the lead-in laced directly to a shielded harness looks to be poor installation practice for this kind of open-wire line. I'm not familiar with acceptable signal and transmission line integrity practices of the 1930's. Close proximity results in a some of your transmitter power shunted somewhere other than the antenna. No doubt that when they did this Photo 3 installation they re-tuned the transmitter output, but that only keeps the transmitter happy.
The shielded harness was apparently done in early March around the time the Bendix RA-1 receiver was installed. Is it providing power to the new receiver? Poor installation practice would be par for the course for the Earhart operation.
You indicate the NTSB lab reported a wire diameter of 0.024". If a precise measurement (neglectable diameter change from corrosion), then this is the exact nominal diameter of 22.5 AWG wire (0.0240"). This is also 0.61mm. Solid magnet wire is available in 1/2 gauge steps in the present era but what about wire in the 1930's?
AWG stands for American Wire Guage - I looked it up :-) As confirmed in the NTSB report, the artifact wire and insulation matches 1938 vintage aviation fairlead.
"The "1938" wire sample had a single strand, solid wire core with an easily fragmented inner insulation and a woven fabric outer covering." The lead-in we see in the photos of the Electra is encased in a fairly thick rubber covering. If the artifact wire is fairlead from the Electra, the rubber covering must have come off over the years.
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The lead-in we see in the photos of the Electra is encased in a fairly thick rubber covering. If the artifact wire is fairlead from the Electra, the rubber covering must have come off over the years.
The rubber covering on shielded cable we found near the island radio shack in 1996 was originally encased in rubber covering that had become brittle and had mostly fallen off.
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Here's a new discovery.
The entry-point insulator for the fairlead to the transmitter had been moved down to right beside transmitter before the plane left Burbank.
In Miami, some time between Saturday, May 29 and Monday, May 31, the attach-point of the fairlead to the antenna was moved forward, thus shortening the effective total antenna length. This was undoubtedly part of Pan Am's efforts to improve the performance of the transmitter.
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Ric
If you look at the photo of the aircraft taxiing in Miami "the morning of her take off" it looks to me like both wires are there, one angled forward from the attach insulator, and one angled to the rear. Is it just my eyes?
See attached and
https://flashbackmiami.com/2016/05/31/june-1st-1937-amelia-earhart-takes-off-from-miami/ (https://flashbackmiami.com/2016/05/31/june-1st-1937-amelia-earhart-takes-off-from-miami/)
Do you have a better resolution copy of this photo?
Andrew
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Thanks, Andrew. For me the Miami_taxiing photo shows up more clearly in the FlashbackMiami link you provided. There what I see is only the one lead-in attached more forward, in the same position as in the Darwin photo that Ric posted. So that verifies what we expected, that the change was indeed made in Miami, and during the same time period in which that starboard navigation window was skinned over (and yes, with that patch in Tighar's possession, I have no doubt!).
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Do you have a better resolution copy of this photo?
Here's a detail from the highest-resolution copy we have. There's only one wire and it's in the forward location.
You can also see what appear to be two of the rivet lines on the shiny new patch.
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In Reply #10 in this topic, I attempted to attach a .jpg of a letter from Joe Gurr to Paul Mantz, but it was too big. Here it is as a .png file. It should come through okay this time.
Thanks to Bill Davenport for pointing out the error.
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Paul Mantz:
Build dural stand for transmitter...
I had to look through several on-line dictionaries to get a non-medical definition of dural. Basically dural is a short form of duralumin.
A change in height would also affect the point at which incoming tides at Gardner would disable the transmitter. Water only has to reach the bottom of the transmitter. It has to reach the top of the aux battery.
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Many thanks to James Champion for his very helpful analysis of the three photos in Ric’s Reply #12.
Let me return our attention to “Photo Two,” the one of AE seated on top of the WE transmitter.
I wish to ask whether we might in this photo be observing a couple of optical illusions --
first, with respect to “Feature C”, and second, as to what AE might be up to, if anything, besides posing for a photo.
First, I suggest that Feature C in this photo is simply the edge of the “crawl-over platform” that also appears in the other two photos. The end of the 1”x1” wood support for the platform is not easy to make out, but it’s there, and once you see it, and look at C again as resting on it, you begin to realize that it’s merely an optical illusion that C appears to be a tube connected with the fuel-tank vent tubing adjacent to the cabin wall. Yes, I could only see it that way at first.
My second optical illusion is this: AE at first appears to be posing a bit oddly, by holding her chin in the palms of her hands. But look again much more carefully. Could she rather in this photo be using headphones? It appears to me that the forefinger of each hand might be pressing to her ear the respective earphone of a headphone set, providing the illusion in the photo of holding her chin.
If she is using headphones, does that tell us anything useful? How and why would there be a headphone jack anywhere near that WE transmitter back in the cabin? That transmitter did not receive, it only transmitted, thus no need for a headphone jack there. Receivers did provide headphone jacks, but the WE 20B communication receiver was about 15 feet forward in the cockpit, and the DF receiver which we cannot see in this photo, if there, was about half that distance forward. So why the headphones there in the cabin?
Here’s one possible explanation: press reports about preparations for the First Try implied that Manning would be able to do radio work from his position in the cabin. To do that he would have needed to have back there a remote control and a headphone jack, connected at least to the WE 20B receiver, duplicating the ones already in the cockpit.
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I don't see headphones. I think she is just posing for the press.
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First, I suggest that Feature C in this photo is simply the edge of the “crawl-over platform” that also appears in the other two photos. The end of the 1”x1” wood support for the platform is not easy to make out, but it’s there, and once you see it, and look at C again as resting on it, you begin to realize that it’s merely an optical illusion that C appears to be a tube connected with the fuel-tank vent tubing adjacent to the cabin wall. Yes, I could only see it that way at first.
I agree. Good catch. There is still the issue of Feature "A". It's not present in either of the other photos and Photo Three definitely post-dates both of the others. Is "A" something that was added early on but removed before the Hooven installation in October 1936? Or is it something that was added after the Hooven installation but removed before March 12, 1937 (the date of Photo Three)?
My second optical illusion is this: AE at first appears to be posing a bit oddly, by holding her chin in the palms of her hands. But look again much more carefully. Could she rather in this photo be using headphones?
The photo below shows what she looked like wearing headphones.
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I agree. Good catch. There is still the issue of Feature "A". It's not present in either of the other photos and Photo Three definitely post-dates both of the others. Is "A" something that was added early on but removed before the Hooven installation in October 1936? Or is it something that was added after the Hooven installation but removed before March 12, 1937 (the date of Photo Three)?
From a purely personal point of view....I know that my pinkie toe, either in a boot or a shoe, would very likely geo-locate feature "A" rather quickly. Perhaps it was removed as it was found to be a trip point or was in a location that caused it to be frequently stepped upon (either the possible connector or the possible grounding lug) resulting in damage, disconnection, or source of injury/hazard???
A question: I'm not seeing "A" in either the "first" or "third" photos on page one of this thread due to camera angle or photo composition. Am I missing something or are these two photos cropped preventing me from seeing that lower corner of the transmitter and/or feature "A"? Or do I need new reading glasses?
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Am I missing something?
No, I am. A brain. I meant to say feature "B", the dial-like thing on the wall.
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No, I am. A brain. I meant to say feature "B", the dial-like thing on the wall.
;D I've have those days.....everyday!!
As mentioned up-thread, "B" very well could be a remote headphone/microphone/Morse key connection point or junction/switch box of some sort. It appears to have 2-3 cables (wiring or something) connected into it.
Could it be related in some way to "E", the possible "wiring loom" in the "third" photo??
Another thought which I'm sure has been covered in the past: How was the deployment and retrieval of the trailing wire antenna controlled? I haven't seen how that worked, just that it was removed before the second attempt. If electrically, perhaps "B" is an extend/retract control? Forgive me if I've missed that bit of detail....
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In Photo One, showing the Hooven DF gear, at the left edge the portside cabin window seems to be lacking that bar or stringer. The Timeline for Dec 10, under the photo of the Cord and AE holding the cabin door partly open, with the dorsal antenna mast clearly visible, states the following:
"The bar through the cabin window (actually a stringer) was removed in January 1937 at the same time windows were added to the cabin door and right-side lavatory area."
If that's correct, it narrows down the time period for Photo One to the time after the navigation windows were installed.
I keep wanting to date Photo Two, with its Feature B round gizmo, as earlier than Photo One, which lacks that gizmo, though I cannot yet prove that. But there was ample time in December for Photo Two to be earlier, even if the dark vertical wire is lead-in from the dorsal antenna that was installed some time before that Cord photo in Burbank.
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My eyes are getting old ..... but what do you think that the object crossing the upper left corner of the 'navigation' window might be in the 'Miami taxi wire.png'? It looks like it crosses the same area of window that the rear connected antenna lead did in previous photos. Curiousier and curiousier.
Bill Torgerson
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To Herbert William Davenport on Reply #27 - OK, I see what you mean about an optical illusion. The line that appears to be going aft-to-forward is actually going left-to-right and is the edge of the crawl-over. I also see what you mean about possible headphones on Amelia.
Now for "B" in photo 2. I keep trying to think of what might be needed in that general area. Could 'the dial-like thing' be an Aux Battery disconnect switch? The location seems unusual unless it was meant to be reachable from the crawl-over without going all the way back to the battery.
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Another thought which I'm sure has been covered in the past: How was the deployment and retrieval of the trailing wire antenna controlled? I haven't seen how that worked, just that it was removed before the second attempt. If electrically, perhaps "B" is an extend/retract control?
I think that's a pretty good guess. The trailing wire originally deployed through the extreme end of the tail as shown in the photo below taken in New Jersey in February 1937. Some time before March 14 it was moved forward and deployed through a mast in the belly just forward of the cabin door. It was a bad set-up, requiring the wire to bend 90° when deployed. We don't know whether the wire was reeled out mechanically or electrically. My guess would be the original installation was mechanical and the second was electrical. If my guess is right, and if "B" is an electrical extend/retract control, it dates the photo to after AE's return to Burbank in February but before the navigation table was installed.
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My eyes are getting old ..... but what do you think that the object crossing the upper left corner of the 'navigation' window might be in the 'Miami taxi wire.png'? It looks like it crosses the same area of window that the rear connected antenna lead did in previous photos.
I'm confused. 'Miami taxi wire.png' shows the patch, not the navigation window and I don't see an object crossing the upper left corner of the patch. The patch is new and shiny, so we see reflections of the people watching the plane taxi out.
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When we first found Artifact 2-2-V-1, there was a length of insulated wire jammed in a tear in the metal.
Returning for a moment to Artifact 2-2-V-1a (which will soon get its own thread), way back in January 1992 aircraft radio historian Norman Chipps of Chipps Research Ltd in Hyattsville, MD looked at photos of the wire and wrote:
"In most cases the [antenna] wire, until later days, was a heavy rubber and varnished cotton covered small gauge conductor which was very flexible. The fairlead wire (wire inside of the aircraft to connect receivers to antennas ) was a small conductor cable with smaller diameter cloth and rubber covering. The 22 gauge wire you have found entangled in artifact 2-2-V-1 could possibly be from the external lead or the internal fairlead. Normally electrical lighting wiring and electrical appliance wiring is supported every 6 to 18 inches but the wire you have has no evidence of mounting brackets unless it had been earlier removed by a person in need of a piece of wire or a salvor trying to recover usable items from a wrecked aircraft."
It was Norm who provided the 1938 and 1941 wire samples the NTSB lab compared to 2-2-V-1a. They found that the artifact matched the 1938 sample. My question is this:
In his letter, Norm specifically mentions "The fairlead wire (wire inside of the aircraft to connect receivers to antennas )."
That may be because, at that time, we were speculating that 2-2-V-1 came from the belly of the Electra in the vicinity of the lead-in to the receiver under the copilots seat. But is there any reason to think the fairlead connecting the belly antenna to the receiver would be any different from the fairlead connecting the dorsal vee to the transmitter?
I'm trying to get back in touch with Norm but we haven't heard from him in many years. He was no spring chicken in 1992. His cell phone number is still active so that's a good sign. I left a message.
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Mr Chipps lived in Wickenburg, AZ, as of 2014.
When we first found Artifact 2-2-V-1, there was a length of insulated wire jammed in a tear in the metal.
Returning for a moment to Artifact 2-2-V-1a (which will soon get its own thread), way back in January 1992 aircraft radio historian Norman Chipps of Chipps Research Ltd in Hyattsville, MD looked at photos of the wire and wrote:
"In most cases the [antenna] wire, until later days, was a heavy rubber and varnished cotton covered small gauge conductor which was very flexible. The fairlead wire (wire inside of the aircraft to connect receivers to antennas ) was a small conductor cable with smaller diameter cloth and rubber covering. The 22 gauge wire you have found entangled in artifact 2-2-V-1 could possibly be from the external lead or the internal fairlead. Normally electrical lighting wiring and electrical appliance wiring is supported every 6 to 18 inches but the wire you have has no evidence of mounting brackets unless it had been earlier removed by a person in need of a piece of wire or a salvor trying to recover usable items from a wrecked aircraft."
It was Norm who provided the 1938 and 1941 wire samples the NTSB lab compared to 2-2-V-1a. They found that the artifact matched the 1938 sample. My question is this:
In his letter, Norm specifically mentions "The fairlead wire (wire inside of the aircraft to connect receivers to antennas )."
That may be because, at that time, we were speculating that 2-2-V-1 came from the belly of the Electra in the vicinity of the lead-in to the receiver under the copilots seat. But is there any reason to think the fairlead connecting the belly antenna to the receiver would be any different from the fairlead connecting the dorsal vee to the transmitter?
I'm trying to get back in touch with Norm but we haven't heard from him in many years. He was no spring chicken in 1992. His cell phone number is still active so that's a good sign. I left a message.
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Thanks Christian. I just got off the phone with Norm. He's alive and kicking and eager to help.
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How was the deployment and retrieval of the trailing wire antenna controlled? I haven't seen how that worked, just that it was removed before the second attempt. If electrically, perhaps "B" is an extend/retract control? Forgive me if I've missed that bit of detail....
Does this 3/3/37 photo show the trailing antenna reel and weight? Could be a small electric motor directly in front of the reel on the floor. (Hope it's not the aileron trim cable again...).
Dan Brown, #2408
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Does this 3/3/37 photo show the trailing antenna reel and weight? Could be a small electric motor directly in front of the reel on the floor. (Hope it's not the aileron trim cable again...).
I knew we had that photo but I couldn't find it. Thanks. Yes, that has to be the tailing wire in the new location, but apparently the mast hasn't been installed yet. That's the ball weight that goes on the end of the wire in the foreground. The rig is anchored to the auxiliary batter box. Gotta be an electric motor. The reel of wire is too close to the floor for there to a be manual crank.
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The third photo was taken March 12, 1937. The navigator's table has been installed (you can see the "goose neck" of the lamp) but features "B" and "C" are no longer present. Also, the fuel tank vent line manifold "D" has been wrapped with wire(?) and there's a bundle of wire or cable "E" running to either the transmitter or the aft battery.
While there are a lot of eyes on this, please consider also this photo from approximately 3/3/37 showing electronics on top of the R1 fuel tank. In the 3/12/37 photo there seem to be cables extending from that same apparatus across the doorframe into the cockpit. What is that apparatus?
Dan Brown, #2408
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If you look at the wiring bundle just behind the black box behind the copilot, you can see that a thick black cable enters the bundle at that point. Some of the other photos in this thread show that this black cable leads to the 3 steam gauges at the Navigator station. The 3 gauges appear to be altitude, fuel quantity (?), and airspeed, which is seen next to Amelia in the 3-3-37 photo along with the trailing antenna rig.
Perhaps this box feeds the fuel gauges fore and aft, or it is some sort of "repeater" junction box for all of the gauges in back?
The third photo was taken March 12, 1937. The navigator's table has been installed (you can see the "goose neck" of the lamp) but features "B" and "C" are no longer present. Also, the fuel tank vent line manifold "D" has been wrapped with wire(?) and there's a bundle of wire or cable "E" running to either the transmitter or the aft battery.
While there are a lot of eyes on this, please consider also this photo from approximately 3/3/37 showing electronics on top of the R1 fuel tank. In the 3/12/37 photo there seem to be cables extending from that same apparatus across the doorframe into the cockpit. What is that apparatus?
Dan Brown, #2408
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My eyes are getting old ..... but what do you think that the object crossing the upper left corner of the 'navigation' window might be in the 'Miami taxi wire.png'? It looks like it crosses the same area of window that the rear connected antenna lead did in previous photos.
I'm confused. 'Miami taxi wire.png' shows the patch, not the navigation window and I don't see an object crossing the upper left corner of the patch. The patch is new and shiny, so we see reflections of the people watching the plane taxi out.
I think he means the object that can be seen through both the starboard and port windows. see this photo
Andrew
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The third photo was taken March 12, 1937. The navigator's table has been installed (you can see the "goose neck" of the lamp) but features "B" and "C" are no longer present. Also, the fuel tank vent line manifold "D" has been wrapped with wire(?) and there's a bundle of wire or cable "E" running to either the transmitter or the aft battery.
While there are a lot of eyes on this, please consider also this photo from approximately 3/3/37 showing electronics on top of the R1 fuel tank. In the 3/12/37 photo there seem to be cables extending from that same apparatus across the doorframe into the cockpit. What is that apparatus?
Dan Brown, #2408
Could it be the coupler or coupling unit component of the Bendix Radio Direction Finding (RDF) system?
That Bendix RDF system was installed in the Electra in Burbank from Friday, Feb 26 to about Friday, March 5, after Bendix radio expert Cyril Remmlein arrived there on Feb 26 from the east coast to supervise the installation. (See Timeline.) That Bendix DF system replaced the Hooven DF system that had been in place in the Electra since the previous October.
It is my understanding that the Bendix DF system had five key components: 1. the familiar overhead open loop antenna; 2. the coupling unit; 3. the Bendix DF receiver; 4. a ‘sense’ antenna; and 5. a remote control unit for operating the system from the cockpit. (There was also a dial in the instrument panel that I will ignore for present purposes.)
The Timeline shows published newspaper publicity photos of three of those components: the loop antenna, the remote control unit, and the receiver. I have never seen a photo of the coupler unit, except for the one you’ve posted, if that is indeed the coupler, and perhaps a few other photos of the cabin like it, in which that black box is barely visible in the background.
I would like to know more about the coupler, in part because of the likelihood that it was retained as a necessary part of the modified DF system that was in place in May for the second attempt. In that modified system, the WE 20B communication receiver under the copilot seat was co-opted into doing double duty as the DF receiver, replacing the Bendix DF receiver which was eliminated from the modified system. My understanding is that the coupler unit was still needed in its place, between the loop antenna and the WE 20B receiver.
For some time I labored under the misunderstanding that the remote control unit pictured in the photos being held by Remmlein was the same thing as the coupler unit, or incorporated all the needed coupling components within its small box. Only recently have I realized my mistake, and I now believe that those coupling components were contained in their own separate larger box, the one we see in the photo posted by Dan Brown.
I hope that Ric and our radio experts will weigh in to correct any misunderstandings on my part and to help further my understanding, as I lack radio expertise and have barely begun to research these issues.
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I think he means the object that can be seen through both the starboard and port windows. see this photo
I dunno what that is, unless it's the seam between the wing and aileron on the left wing.
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The "steam guages" beside the window are, top to bottom, altitude, outside air temperature, and indicated airspeed - all needed by the navigator to calculate True Airspeed.
I hope that Ric and our radio experts will weigh in to correct any misunderstandings on my part and to help further my understanding, as I lack radio expertise and have barely begun to research these issues.
Thank you for making a distinction between me and a radio expert which - despite the best efforts of the the U.S. Army Signal Corps Advanced Radio Systems School at Ft. Monmouth, NJ - I most certainly am not.
That said, I think you nailed it. Remmlein shows up to supervise the installation on Feb 26. We don't know exactly when the RA-1 receiver was installed but it's present in the March 12 photo. There are photos dated March 7 of AE posing with the about-to-be installed-loop. The photo Dan posted is circa March 3. I think the box is the loop coupler. There's no wire going forward because the loop has not been mounted yet. BY March 12 the loop has been installed and the wire going from the box into the cockpit is headed straight for the base of the loop.
Nice work gentlemen.
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After more (much more) analysis of photos and written source material, we have reason to believe the antenna set-up on NR16020 at the time of the aircraft's disappearance was different than we previously thought. As a reminder, there were three antennas on the Electra when it arrived in Lae.
• Dorsal vee wires from a mast on top of the fuselage to each vertical fin.
• A belly wire extending extending along the starboard underside of the fuselage.
• A loop antenna above the cockpit.
We have long believed the dorsal vee was used exclusively for transmitting and the belly antenna for receiving. The loop was used for DF (direction finding). Hence, the loss of the belly antenna on takeoff conveniently explained why Earhart was unable to hear Itasca's voice transmissions on 3105 but when trying to DF on Itasca she was able to hear the transmission via the loop.
Earhart's Western Electric 13C transmitter had a receiver relay terminal which allowed the transmitter and receiver to share the same antenna. Our belief that this feature was not used was based on a photo of the cabin in which the terminals on the transmitter are visible. The receiver relay terminal is clearly unused (see below). However, that photo shows the cabin as it was when the airplane was equipped with the Hooven Radio Compass system and before the installation of a "navigator's station" in early March 1937. At that time, the Hooven system was replaced with a Bendix system, a plywood table was built over the transmitter, and duplicates of some cockpit instruments (altimeter, airspeed indicator, and outside air temperature gauge) were installed for the navigator. A series of photos of Earhart sitting on the navigator's table, when correctly daed in sequence, shows the instruments were first installed on the cabin wall beside the window but were later moved down into the table.
In a photo of the cabin taken on March 12, 1937 (see below) there is a bundle of cables extending aft, secured to the fuselage fuel tank vent manifold. The cables probably serve the duplicated cockpit instruments mounted in the table. Included with the cables is a black wire that leaves the bundle and goes to a different destination. It is most logically a line from the receiver to the receiver relay terminal on the transmitter, thus allowing the dorsal vee to be used for both transmitting and receiving.
Such a change would be a smart move. The belly antenna was poorly situated for receiving unless the aircraft was close enough to the station to receive signals via "groundwave" (about 30 miles). At greater distances, signals arriving from above as "skywave" (bounced off the ionosphere) are blocked by the fuselage. The March 12 photo is the last photo we have of the cabin, so we don't know what it looked like for the second world flight attempt. We do know that, during the rebuild after the wreck in Hawaii and Manning's departure from the project, the trailing wire was not reinstalled and the Bendix receiver was removed, but there is no reason to think the ability to use the dorsal vee for both transmitting and receiving was not retained. That would explain why the port-side belly antenna was not replaced. The Bendix direction finder needed a "sense" antenna to resolve "180° ambiguity." The starboard-side belly antenna could serve that purpose.
Of course, if the dorsal vee was being used to receive, we need a new hypothesis for why Earhart was not able to hear Itasca on 3105 but was able to hear the signals sent on 7500. There is a simple explanation:
During the test flight on July 1st, Earhart was able to hear the station at Lae on Lae's frequency, 6522 kHz, so she must have had Band 4 (4000 to 10,000 kHz) selected on the WE20B. The was no need to change the setting when she left for Howland the next morning because she planned to receive hourly weather reports from Lae. Whether she ever heard them is debatable. If she later tuned the receiver to 3105 to listen for Itasca without switching to Band 3 (1500 to 4000 kHz) she wouldn't hear anything, but when she tuned to 7500 to use the loop, with the receiver still set on Band 4, she would hear the signal. The loss of the belly antenna on takeoff meant only that, without a “sense” antenna, the direction finder would not be able to resolve “180° ambiguity,” but the point is moot because the 7500 frequency was far above the DF’s 1500 kHz limit.
On the reef at Gardner, she must have realized her error because that evening she seems to have been able to hear Itasca on 3105 and send the dashes they requested that were heard by Achilles and New Zealand Star. She has to be on Band 3 to hear Itasca. To later hear KGMB on 1320 kHz she has to be on Band 2 (550 to 1500 kHz).
If our conclusions are correct, there are two take-aways from this new research.
• Earhart's failure to hear Itasca was due to operator error, not an accident on takeoff.
• If Artifact 2-2-V-1a is from the Electra, it is most likely internal receiver feed line. If the receiver under the copilot seat was connected to both the belly antenna and the transmitter in the cabin, there was much more internal receiver feed line aboard the airplane than we thought.
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Ric...are you by chance seeing part of the window from the other side?
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Ric...are you by chance seeing part of the window from the other side?
I'm not sure I understand your question. Part of the port-side cabin window is visible in the Jan/Feb 1937 photo. No window is visible in the March 12, 1937 photo.
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So, in the March 12, 1937 picture, the dorsal vee lead in is just-out-of frame to the right.
To get a 'repeater' of the cockpit altimeter and airspeed to the navigators table would have required two pressure tubes with a pitot-static port system. I don't think the technology of the 30's would allow for mechanical diaphragm-pressure based instruments like these to be repeated electrically. I would guess-estimate that a 'repeater' for air temperature would need 3 to 4 wires.
What I'm getting at is the size/routing/bending of the shielded wire bundle we see in the March 12, 1937 picture explained fully by the needs of these three instruments? I state 'bending' as ideally these pressure based indicators would be routed with metal tubing. I say ideally as they might have used rubber hose, but would that lead to instrument accuracy issues? Is the shielding on this harness really an attempt to constrain flexible hoses from vibrating and/or changing size with pressure? Is what is marked in the photo as "Receiver line" actually one of the pressure lines?
I'm just pondering these issues outloud.
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So, in the March 12, 1937 picture, the dorsal vee lead in is just-out-of frame to the right.
Yes.
To get a 'repeater' of the cockpit altimeter and airspeed to the navigators table would have required two pressure tubes with a pitot-static port system. I don't think the technology of the 30's would allow for mechanical diaphragm-pressure based instruments like these to be repeated electrically. I would guess-estimate that a 'repeater' for air temperature would need 3 to 4 wires.
What I'm getting at is the size/routing/bending of the shielded wire bundle we see in the March 12, 1937 picture explained fully by the needs of these three instruments?
I don't know.
I state 'bending' as ideally these pressure based indicators would be routed with metal tubing.
The wire bundle is new. I don't see any new metal tubing.
I say ideally as they might have used rubber hose, but would that lead to instrument accuracy issues? Is the shielding on this harness really an attempt to constrain flexible hoses from vibrating and/or changing size with pressure? Is what is marked in the photo as "Receiver line" actually one of the pressure lines?
I can't say it's not, but it's different from everything else in the bundle and it leaves the bundle as it comes down the wall and appears to be headed for a different destination.
I'm just pondering these issues outloud.
Pondering is good.
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Mr. McKenna:
My apologies but I have been away from the forum for a bit. However this is the photo my comment was referring to. If you look at the 'high resolution' version of this photo you can see whatever 'it' is clearly crossing the upper left of the navigation window. To me 'it' appears to be inside the aircraft.
Bill
3046R
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If our conclusions are correct, there are two take-aways from this new research.
• Earhart's failure to hear Itasca was due to operator error, not an accident on takeoff.
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I accept it was not the loss of the belly antenna that directly resulted in the inability to receive, but is operator error the only possible, or even likely, conclusion?
* When your radio doesn’t receive, isn’t the first thing you do is flip the receiver’s controls on and off and into different positions to eliminate a transient fault and confirm that you have the proper setting?
* Is it possible that Earhart was so unfamiliar with this receiver that she wouldn’t properly position the band selector, and would not repeatedly check its position?
* When the belly antenna was ripped out (violently I might add) is there a possibility of damage to the other antenna and/or the receiver?
I am sure there are other possibly reasons.
We should not default to operator error until we have done our best to eliminate the alternatives.
Thanks,
Jon Romig
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I accept it was not the loss of the belly antenna that directly resulted in the inability to receive, but is operator error the only possible, or even likely, conclusion?
It's a fair question.
* When your radio doesn’t receive, isn’t the first thing you do is flip the receiver’s controls on and off and into different positions to eliminate a transient fault and confirm that you have the proper setting?
I've never had a receiver fail but I've frequently failed to get a response when being handed off from one controller to another. The solution is to check that you've correctly selected the new frequency, try again, and if no response go back to the previous controller and request a different frequency. Today, changing frequencies is a simple matter of dialing it in. For Earhart, changing frequencies was a multi-step process that may or may not involve changing bands.
* Is it possible that Earhart was so unfamiliar with this receiver that she wouldn’t properly position the band selector, and would not repeatedly check its position?
It was the same receiver the airplane was delivered with but she seems to have rarely used it.
* When the belly antenna was ripped out (violently I might add) is there a possibility of damage to the other antenna and/or the receiver?
It's hard to see how the loss of the belly antenna would have any effect on the dorsal antenna. The two were not connected. The receiver itself was clearly working because she was able to hear Itasca on 7500.
We should not default to operator error until we have done our best to eliminate the alternatives.
I agree, but that's kinda what we did, and it fits a pattern. Time and again with Earhart, communications problems are traceable to operator error, i.e. trusting Joe Gurr to set up her radios and antennas while the plane was being repaired, not being able to diagnose and repair a simple blown fuse which disabled the receiver for much of the world flight, incorrectly converting meters to kilocycles in Darwin, blaming the DF's failure to home on Lae during the testflight to being too close to the station, and ultimately, asking Itasca to send signals on a frequency her DF could not respond to.
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Here's a puzzle...... <snip>... but what's the connection at "A" going down through the floor?
Yup, definitely a ground lug - see the first photo below.
For Earhart, changing frequencies was a multi-step process that may or may not involve changing bands.
In reference to the second and third photos below: The band switch is the upper rightmost knob on the receiver remote control unit. I can see that having to look AND reach across to a knob behind the yoke AND adjust the crank to tune to the correct frequency might have been one too many things to deal with when things became dicey as they reached the advanced LOP. Under ordinary circumstances, it wouldn't be a big deal.....but Amelia and Fred were not in an ordinary situation. Flying fatigue had to be a contributing element.
(Don't ask me how many times I've forgotten to switch the work truck out of 4WD until I was more than a ways off the mountain and on pavement....and that 4WD switch is right in front of me, I haven't been driving for 20+ hours, and I'm firmly on the ground!) ;D
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Ric...In response to your recent post about new theories on the antennas aboard the Electra...I have a question and it goes back to when you guys had one of your very first ROV missions and took several videos from that. But, do you remember the cable that was found several yards from the reef and it was everywhere. Did you guys come to an analysis on what that cable was and where it came from? Also, in relation to extra cable that may have been onboard the Electra...Is it possible that Noonan and Earhart tried the old shortwave radio method with running antenna cable along the ground. I personally saw this being done from a shortwave "Ham" radio operator several years. As a matter of fact, my friend Tim was the engineer at HJCB Radio in Quito, Equidor and had showed us how that was done. At the time he had several major radio antennas that they used for their broadcast and was very knowledgeable. Also, wandering and help me out with this, cause I'm definately no radio man...but will the radio transmitter/receiver work by itself without the help of starting the motors to the plane. Also, if antenna cables on the bottom of the plane are submerged in salt water will they still do the job effectively or not? Also, how fast would it take Noonan and Earhart to remove the radio from the plane if need to be in case of total destruction of the plane from going over the reef? Or is that possible at all?
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But, do you remember the cable that was found several yards from the reef and it was everywhere.
No cable was found. There was what appeared to be a small piece of wire and there was a length of rope. Elsewhere there was a tangle of fishing net.
Also, if antenna cables on the bottom of the plane are submerged in salt water will they still do the job effectively or not?
Not, but the belly antenna was lost on takeoff anyway.
Also, how fast would it take Noonan and Earhart to remove the radio from the plane if need to be in case of total destruction of the plane from going over the reef? Or is that possible at all?
The radios, power supply, and antennas were an integral part of the plane and would not work if removed
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John Romig asked above about damage inside the aircraft when the belly antenna was lost when taking off at Lae. I expect the antenna broke free at the point where the lead wire connects to the antenna (that would seem to be a weak point), but I have to wonder if enough force would have transferred inside to stretch or break the lead wire where it attached to the receiver. I wonder if that would have been something Fred could have noticed.
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I expect the antenna broke free at the point where the lead wire connects to the antenna (that would seem to be a weak point)
It's hard to say. The antenna was attached to the starboard-side pitot tube, a mast roughly amidship, and a mast aft. We've speculated that the aft mast was knocked off as the airplane swung around to begin its takeoff run, with the antenna wire now dragging the broken mast along the ground. The puff of dust we see in the takeoff film might be the broken mast snagging on something and ripping the wire free. I would think the external feed line would fail where it attaches to the fairlead insulator.
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In reply #49, Ric says:
>>If she later tuned the receiver to 3105 to listen for Itasca without switching to Band 3 (1500 to 4000 kHz) she wouldn't hear anything, but when she tuned to 7500 to use the loop, with the receiver still set on Band 4.
Do we know if this is actually possible to do - does the dial and (apparent) selectable range for Band 4 on the remote control unit go that far below 4000kHz down to 3105kHz ?
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does the dial and (apparent) selectable range for Band 4 on the remote control unit go that far below 4000kHz down to 3105kHz ?
The central dial shows the complete range of frequencies from 200 up to 10,000 kHz. By cranking the Tuning Control you can set the needle on any frequency regardless of what band you have selected on the Band Selector. Unfortunately, we don't have a detailed image of the central dial.