Removal of trailing antenna - Revision history

Moleski at 15:48, 13 October 2009

2009-10-13T15:48:23Z

← Older revision		Revision as of 15:48, 13 October 2009
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	=== Exit point relocated ===		=== Exit point relocated ===

	"A trailing wire antenna came standard with the Lockheed Model 10. [[Earhart]]'s Model 10E Special was delivered with a trailing wire antenna installed in the tail, visible externally as a small white cone protruding just below the tail nav light. ... Sometime in January or February of 1937, as part of the preparations for the first World Flight attempt, that antenna was removed and was replaced by a different type of trailing wire unit mounted in the cabin. This antenna is visible externally as a mast sticking down from the belly just forward of the cabin door. On the end of the mast is a lump which is, in fact, the lead weight on the end of the wire. Oddly, the mast protrudes from the belly at a right angle rather than at the customary shallow angle which allows the wire to play out more directly into the slipstream."<ref>[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]</ref>		"A trailing wire antenna came standard with the Lockheed Model 10. [[Earhart]]'s Model 10E Special was delivered with a trailing wire antenna installed in the tail, visible externally as a small white cone protruding just below the tail nav light. ... Sometime in January or February of 1937, as part of the preparations for the first World Flight attempt, that antenna was removed and was replaced by a different type of trailing wire unit mounted in the cabin. This antenna is visible externally as a mast sticking down from the belly just forward of the cabin door. On the end of the mast is a lump which is, in fact, the lead weight on the end of the wire. Oddly, the mast protrudes from the belly at a right angle rather than at the customary shallow angle which allows the wire to play out more directly into the slipstream."<ref>[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/Projects/Earhart/forum/Forum_Archives/199801.txt Forum.]</ref>

	=== Potentially unreliable ===		=== Potentially unreliable ===
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	=== Aboard NR16020 ===		=== Aboard NR16020 ===

	"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>		"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/Projects/Earhart/forum/Highlights101_120/highlights104.html Forum].</ref>

	"The trailing wire’s disadvantage was that it had to be reeled out after takeoff and in before landing. A manual switch was also needed to transfer the transmitter output from the H-F Vee to the L-F trailing wire. This switch, necessarily, was located close to the transmitter which was mounted in the aft section of the fuselage next to the navigator's table. Since the fuselage was almost filled with huge fuel tanks between the navigator’s station and the cockpit, it was very awkward to change antennas if the navigator was riding up front."<ref>[[Mike Everette]], [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>		"The trailing wire’s disadvantage was that it had to be reeled out after takeoff and in before landing. A manual switch was also needed to transfer the transmitter output from the H-F Vee to the L-F trailing wire. This switch, necessarily, was located close to the transmitter which was mounted in the aft section of the fuselage next to the navigator's table. Since the fuselage was almost filled with huge fuel tanks between the navigator’s station and the cockpit, it was very awkward to change antennas if the navigator was riding up front."<ref>[[Mike Everette]], [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>
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	== Removal after [[Luke Field\| Luke Field crash]] ==		== Removal after [[Luke Field\| Luke Field crash]] ==

	[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]		[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/Projects/Earhart/forum/Forum_Archives/199801.txt Forum.]

	When Earhart wrecked the airplane in Hawaii on March 20, 1937 the trailing wire installation was, of course, crushed. Photos of the airplane in Burbank on May 20, 1937 (the day after repairs were completed) show no trailing wire in the tail or on the belly. A letter written to Earhart author [[Fred Goerner]] in 1982 by [[Joseph Gurr]] who claimed to be Earhart's radio consultant alleged that the trailing wire installation was left aboard at this time but not hooked up. All we can say for sure is that there is no evidence of the antenna visible externally when the airplane emerged from the repair shop.		When Earhart wrecked the airplane in Hawaii on March 20, 1937 the trailing wire installation was, of course, crushed. Photos of the airplane in Burbank on May 20, 1937 (the day after repairs were completed) show no trailing wire in the tail or on the belly. A letter written to Earhart author [[Fred Goerner]] in 1982 by [[Joseph Gurr]] who claimed to be Earhart's radio consultant alleged that the trailing wire installation was left aboard at this time but not hooked up. All we can say for sure is that there is no evidence of the antenna visible externally when the airplane emerged from the repair shop.

Moleski at 00:12, 13 October 2009

2009-10-13T00:12:38Z

← Older revision		Revision as of 00:12, 13 October 2009
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	== Purpose of the trailing antenna ==		== Purpose of the trailing antenna ==
	The trailing antenna on the [[Electra]] was installed to communicate on 500 kHz. "In 1937, this was the international distress frequency, employed aboard ships since the early days of radio and consequently adopted for aircraft."<ref>[http://~~www.~~tighar.org/Projects/Earhart/Research/~~Bulletins~~/~~52_ElectraRadios~~/~~52_ElectraRadios~~.htm Electra Radios]</ref>		The trailing antenna on the [[Electra]] was installed to communicate on 500 kHz. "In 1937, this was the international distress frequency, employed aboard ships since the early days of radio and consequently adopted for aircraft."<ref>[http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm Electra Radios]</ref>

	500 kHz is a low frequency and therefore has a [[wavelength\| long wavelength]]. Long wavelengths require long antennas for effective transmission.		500 kHz is a low frequency and therefore has a [[wavelength\| long wavelength]]. Long wavelengths require long antennas for effective transmission.
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	=== As delivered ===		=== As delivered ===

	"For 500 KHz, a second antenna was originally employed. This antenna was the trailing-wire type. The antenna was reeled out from the belly of the aircraft and had a full length of 250 feet. This was still shorter than a resonant length at 500 KHz, but a much larger relative component of the wavelength than the [[dorsal antenna\|46-foot Vee]]. With the addition of a special loading coil, mounted inside the fuselage near the transmitter, connected in series with the antenna to electrically lengthen it, the trailing wire could be effectively [[frequency\|matched to the transmitter]]."<ref>[[Mike Everette]], [http://~~www.~~tighar.org/Projects/Earhart/Research/~~Bulletins~~/~~52_ElectraRadios~~/~~52_ElectraRadios~~.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>		"For 500 KHz, a second antenna was originally employed. This antenna was the trailing-wire type. The antenna was reeled out from the belly of the aircraft and had a full length of 250 feet. This was still shorter than a resonant length at 500 KHz, but a much larger relative component of the wavelength than the [[dorsal antenna\|46-foot Vee]]. With the addition of a special loading coil, mounted inside the fuselage near the transmitter, connected in series with the antenna to electrically lengthen it, the trailing wire could be effectively [[frequency\|matched to the transmitter]]."<ref>[[Mike Everette]], [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

	=== Exit point relocated ===		=== Exit point relocated ===
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	"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>		"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>

	"The trailing wire’s disadvantage was that it had to be reeled out after takeoff and in before landing. A manual switch was also needed to transfer the transmitter output from the H-F Vee to the L-F trailing wire. This switch, necessarily, was located close to the transmitter which was mounted in the aft section of the fuselage next to the navigator's table. Since the fuselage was almost filled with huge fuel tanks between the navigator’s station and the cockpit, it was very awkward to change antennas if the navigator was riding up front."<ref>[[Mike Everette]], [http://~~www.~~tighar.org/Projects/Earhart/Research/~~Bulletins~~/~~52_ElectraRadios~~/~~52_ElectraRadios~~.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>		"The trailing wire’s disadvantage was that it had to be reeled out after takeoff and in before landing. A manual switch was also needed to transfer the transmitter output from the H-F Vee to the L-F trailing wire. This switch, necessarily, was located close to the transmitter which was mounted in the aft section of the fuselage next to the navigator's table. Since the fuselage was almost filled with huge fuel tanks between the navigator’s station and the cockpit, it was very awkward to change antennas if the navigator was riding up front."<ref>[[Mike Everette]], [http://tighar.org/Projects/Earhart/Research/ResearchPapers/ElectraRadios/ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

	== Removal after [[Luke Field\| Luke Field crash]] ==		== Removal after [[Luke Field\| Luke Field crash]] ==

Moleski at 23:13, 12 October 2009

2009-10-12T23:13:00Z

← Older revision		Revision as of 23:13, 12 October 2009
Line 1:		Line 1:
	== Purpose of the trailing antenna ==		== Purpose of the trailing antenna ==
	The trailing antenna on the [[Electra]] was installed to communicate on 500 kHz. "In 1937, this was the international distress frequency, employed aboard ships since the early days of radio and consequently adopted for aircraft."<ref>[http://www.tighar.org/Projects/Earhart/Bulletins/52_ElectraRadios/52_ElectraRadios.htm Electra Radios]</ref>		The trailing antenna on the [[Electra]] was installed to communicate on 500 kHz. "In 1937, this was the international distress frequency, employed aboard ships since the early days of radio and consequently adopted for aircraft."<ref>[http://www.tighar.org/Projects/Earhart/Research/Bulletins/52_ElectraRadios/52_ElectraRadios.htm Electra Radios]</ref>

	500 kHz is a low frequency and therefore has a [[wavelength\| long wavelength]]. Long wavelengths require long antennas for effective transmission.		500 kHz is a low frequency and therefore has a [[wavelength\| long wavelength]]. Long wavelengths require long antennas for effective transmission.
Line 10:		Line 10:
	=== As delivered ===		=== As delivered ===

	"For 500 KHz, a second antenna was originally employed. This antenna was the trailing-wire type. The antenna was reeled out from the belly of the aircraft and had a full length of 250 feet. This was still shorter than a resonant length at 500 KHz, but a much larger relative component of the wavelength than the [[dorsal antenna\|46-foot Vee]]. With the addition of a special loading coil, mounted inside the fuselage near the transmitter, connected in series with the antenna to electrically lengthen it, the trailing wire could be effectively [[frequency\|matched to the transmitter]]."<ref>[[Mike Everette]], [http://www.tighar.org/Projects/Earhart/Bulletins/52_ElectraRadios/52_ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>		"For 500 KHz, a second antenna was originally employed. This antenna was the trailing-wire type. The antenna was reeled out from the belly of the aircraft and had a full length of 250 feet. This was still shorter than a resonant length at 500 KHz, but a much larger relative component of the wavelength than the [[dorsal antenna\|46-foot Vee]]. With the addition of a special loading coil, mounted inside the fuselage near the transmitter, connected in series with the antenna to electrically lengthen it, the trailing wire could be effectively [[frequency\|matched to the transmitter]]."<ref>[[Mike Everette]], [http://www.tighar.org/Projects/Earhart/Research/Bulletins/52_ElectraRadios/52_ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

	=== Exit point relocated ===		=== Exit point relocated ===
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	"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>		"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>

	"The trailing wire’s disadvantage was that it had to be reeled out after takeoff and in before landing. A manual switch was also needed to transfer the transmitter output from the H-F Vee to the L-F trailing wire. This switch, necessarily, was located close to the transmitter which was mounted in the aft section of the fuselage next to the navigator's table. Since the fuselage was almost filled with huge fuel tanks between the navigator’s station and the cockpit, it was very awkward to change antennas if the navigator was riding up front."<ref>[[Mike Everette]], [http://www.tighar.org/Projects/Earhart/Bulletins/52_ElectraRadios/52_ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>		"The trailing wire’s disadvantage was that it had to be reeled out after takeoff and in before landing. A manual switch was also needed to transfer the transmitter output from the H-F Vee to the L-F trailing wire. This switch, necessarily, was located close to the transmitter which was mounted in the aft section of the fuselage next to the navigator's table. Since the fuselage was almost filled with huge fuel tanks between the navigator’s station and the cockpit, it was very awkward to change antennas if the navigator was riding up front."<ref>[[Mike Everette]], [http://www.tighar.org/Projects/Earhart/Research/Bulletins/52_ElectraRadios/52_ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

	== Removal after [[Luke Field\| Luke Field crash]] ==		== Removal after [[Luke Field\| Luke Field crash]] ==

Moleski at 14:55, 28 February 2009

2009-02-28T14:55:36Z

← Older revision		Revision as of 14:55, 28 February 2009
Line 4:		Line 4:
	500 kHz is a low frequency and therefore has a [[wavelength\| long wavelength]]. Long wavelengths require long antennas for effective transmission.		500 kHz is a low frequency and therefore has a [[wavelength\| long wavelength]]. Long wavelengths require long antennas for effective transmission.

	~~Most accounts say that~~ the ~~antenna was capable of being~~ extended 250 feet.		The trailing antenna on the Electra could be extended 250 feet.

	== Design of the trailing antenna ==		== Design of the trailing antenna ==
	=== ~~Theory~~ ===
			=== As delivered ===

	"For 500 KHz, a second antenna was originally employed. This antenna was the trailing-wire type. The antenna was reeled out from the belly of the aircraft and had a full length of 250 feet. This was still shorter than a resonant length at 500 KHz, but a much larger relative component of the wavelength than the [[dorsal antenna\|46-foot Vee]]. With the addition of a special loading coil, mounted inside the fuselage near the transmitter, connected in series with the antenna to electrically lengthen it, the trailing wire could be effectively [[frequency\|matched to the transmitter]]."<ref>[[Mike Everette]], [http://www.tighar.org/Projects/Earhart/Bulletins/52_ElectraRadios/52_ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>		"For 500 KHz, a second antenna was originally employed. This antenna was the trailing-wire type. The antenna was reeled out from the belly of the aircraft and had a full length of 250 feet. This was still shorter than a resonant length at 500 KHz, but a much larger relative component of the wavelength than the [[dorsal antenna\|46-foot Vee]]. With the addition of a special loading coil, mounted inside the fuselage near the transmitter, connected in series with the antenna to electrically lengthen it, the trailing wire could be effectively [[frequency\|matched to the transmitter]]."<ref>[[Mike Everette]], [http://www.tighar.org/Projects/Earhart/Bulletins/52_ElectraRadios/52_ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

			=== Exit point relocated ===

	"A trailing wire antenna came standard with the Lockheed Model 10. [[Earhart]]'s Model 10E Special was delivered with a trailing wire antenna installed in the tail, visible externally as a small white cone protruding just below the tail nav light. ... Sometime in January or February of 1937, as part of the preparations for the first World Flight attempt, that antenna was removed and was replaced by a different type of trailing wire unit mounted in the cabin. This antenna is visible externally as a mast sticking down from the belly just forward of the cabin door. On the end of the mast is a lump which is, in fact, the lead weight on the end of the wire. Oddly, the mast protrudes from the belly at a right angle rather than at the customary shallow angle which allows the wire to play out more directly into the slipstream."<ref>[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]</ref>		"A trailing wire antenna came standard with the Lockheed Model 10. [[Earhart]]'s Model 10E Special was delivered with a trailing wire antenna installed in the tail, visible externally as a small white cone protruding just below the tail nav light. ... Sometime in January or February of 1937, as part of the preparations for the first World Flight attempt, that antenna was removed and was replaced by a different type of trailing wire unit mounted in the cabin. This antenna is visible externally as a mast sticking down from the belly just forward of the cabin door. On the end of the mast is a lump which is, in fact, the lead weight on the end of the wire. Oddly, the mast protrudes from the belly at a right angle rather than at the customary shallow angle which allows the wire to play out more directly into the slipstream."<ref>[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]</ref>

	"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>		=== Potentially unreliable ===

	Prior to the [[first attempt]], "we got into a hassle about the trailing wire antenna installed in the airplane, and which was intended for use on 500 kilohertz. I had previous experience with trailing wires, and it is an efficient radiator. However they are not reliable mechanically. The wire has a rather heavy lead ball attached to its end. An airplane moving at cruising speed puts an enormous strain on this wire, and the wire is subject to breaking, especially in rough air, the lead ball can break off, and you have no antenna. Airlines used them in the early days when low frequencies were used, and they soon discarded them.<ref>[[Gurr]] to [[Goerner]], 3 May 1982.</ref>		Prior to the [[first attempt]], "we got into a hassle about the trailing wire antenna installed in the airplane, and which was intended for use on 500 kilohertz. I had previous experience with trailing wires, and it is an efficient radiator. However they are not reliable mechanically. The wire has a rather heavy lead ball attached to its end. An airplane moving at cruising speed puts an enormous strain on this wire, and the wire is subject to breaking, especially in rough air, the lead ball can break off, and you have no antenna. Airlines used them in the early days when low frequencies were used, and they soon discarded them.<ref>[[Gurr]] to [[Goerner]], 3 May 1982.</ref>

	== Using a trailing antenna ==		== Using a trailing antenna ==

			=== General considerations ===

	Depending on the communication needs of any particular aircraft, the trailing antenna might be extended for the whole flight and retracted before landing. In other situations, it would make sense to extend the antenna only when it was needed.		Depending on the communication needs of any particular aircraft, the trailing antenna might be extended for the whole flight and retracted before landing. In other situations, it would make sense to extend the antenna only when it was needed.
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	Since Earhart had only one [[frequency\| low-frequency, long-wavelength]] band on her transmitter (500 kcs or 500 kHz), the optimum extension of the antenna was 246 feet--one eighth of the 500 kcs wavelength. The [[modifications by Joe Gurr]] were intended to allow some 500 kcs capacity on the [[dorsal antenna]] without extending the trailing antenna; when Gurr made the modifications to the radio system in Burbank before the [[first round-the-world attempt]], he left the trailing antenna system intact so that the radio operator ([[Manning]]) could decide which antenna to use.		Since Earhart had only one [[frequency\| low-frequency, long-wavelength]] band on her transmitter (500 kcs or 500 kHz), the optimum extension of the antenna was 246 feet--one eighth of the 500 kcs wavelength. The [[modifications by Joe Gurr]] were intended to allow some 500 kcs capacity on the [[dorsal antenna]] without extending the trailing antenna; when Gurr made the modifications to the radio system in Burbank before the [[first round-the-world attempt]], he left the trailing antenna system intact so that the radio operator ([[Manning]]) could decide which antenna to use.

			=== Aboard NR16020 ===

			"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>

			"The trailing wire’s disadvantage was that it had to be reeled out after takeoff and in before landing. A manual switch was also needed to transfer the transmitter output from the H-F Vee to the L-F trailing wire. This switch, necessarily, was located close to the transmitter which was mounted in the aft section of the fuselage next to the navigator's table. Since the fuselage was almost filled with huge fuel tanks between the navigator’s station and the cockpit, it was very awkward to change antennas if the navigator was riding up front."<ref>[[Mike Everette]], [http://www.tighar.org/Projects/Earhart/Bulletins/52_ElectraRadios/52_ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

	== Removal after [[Luke Field\| Luke Field crash]] ==		== Removal after [[Luke Field\| Luke Field crash]] ==

Moleski: /* Design of the trailing antenna */

2009-02-28T14:40:48Z

Design of the trailing antenna

← Older revision		Revision as of 14:40, 28 February 2009
Line 7:		Line 7:

	== Design of the trailing antenna ==		== Design of the trailing antenna ==
			=== Theory ===
			"For 500 KHz, a second antenna was originally employed. This antenna was the trailing-wire type. The antenna was reeled out from the belly of the aircraft and had a full length of 250 feet. This was still shorter than a resonant length at 500 KHz, but a much larger relative component of the wavelength than the [[dorsal antenna\|46-foot Vee]]. With the addition of a special loading coil, mounted inside the fuselage near the transmitter, connected in series with the antenna to electrically lengthen it, the trailing wire could be effectively [[frequency\|matched to the transmitter]]."<ref>[[Mike Everette]], [http://www.tighar.org/Projects/Earhart/Bulletins/52_ElectraRadios/52_ElectraRadios.htm A Technical Analysis of the Western Electric Radio Communications Equipment Installed on Board Lockheed Electra NR16020.]</ref>

	"A trailing wire antenna came standard with the Lockheed Model 10. [[Earhart]]'s Model 10E Special was delivered with a trailing wire antenna installed in the tail, visible externally as a small white cone protruding just below the tail nav light. ... Sometime in January or February of 1937, as part of the preparations for the first World Flight attempt, that antenna was removed and was replaced by a different type of trailing wire unit mounted in the cabin. This antenna is visible externally as a mast sticking down from the belly just forward of the cabin door. On the end of the mast is a lump which is, in fact, the lead weight on the end of the wire. Oddly, the mast protrudes from the belly at a right angle rather than at the customary shallow angle which allows the wire to play out more directly into the slipstream."<ref>[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]</ref>		"A trailing wire antenna came standard with the Lockheed Model 10. [[Earhart]]'s Model 10E Special was delivered with a trailing wire antenna installed in the tail, visible externally as a small white cone protruding just below the tail nav light. ... Sometime in January or February of 1937, as part of the preparations for the first World Flight attempt, that antenna was removed and was replaced by a different type of trailing wire unit mounted in the cabin. This antenna is visible externally as a mast sticking down from the belly just forward of the cabin door. On the end of the mast is a lump which is, in fact, the lead weight on the end of the wire. Oddly, the mast protrudes from the belly at a right angle rather than at the customary shallow angle which allows the wire to play out more directly into the slipstream."<ref>[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]</ref>

Moleski: /* Design of the trailing antenna */

2009-02-25T20:18:41Z

Design of the trailing antenna

← Older revision		Revision as of 20:18, 25 February 2009
Line 12:		Line 12:
	"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>		"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>

	"~~At this point~~ we got into a hassle about the trailing wire antenna installed in the airplane, and which was intended for use on 500 kilohertz. I had previous experience with trailing wires, and it is an efficient radiator. However they are not reliable mechanically. The wire has a rather heavy lead ball attached to its end. An airplane moving at cruising speed puts an enormous strain on this wire, and the wire is subject to breaking, especially in rough air, the lead ball can break off, and you have no antenna. Airlines used them in the early days when low frequencies were used, and they soon discarded them.<ref>[[Gurr]] to [[Goerner]], 3 May 1982.</ref>		Prior to the [[first attempt]], "we got into a hassle about the trailing wire antenna installed in the airplane, and which was intended for use on 500 kilohertz. I had previous experience with trailing wires, and it is an efficient radiator. However they are not reliable mechanically. The wire has a rather heavy lead ball attached to its end. An airplane moving at cruising speed puts an enormous strain on this wire, and the wire is subject to breaking, especially in rough air, the lead ball can break off, and you have no antenna. Airlines used them in the early days when low frequencies were used, and they soon discarded them.<ref>[[Gurr]] to [[Goerner]], 3 May 1982.</ref>

	== Using a trailing antenna ==		== Using a trailing antenna ==

Moleski: /* Design of the trailing antenna */

2009-02-25T20:17:48Z

Design of the trailing antenna

← Older revision		Revision as of 20:17, 25 February 2009
Line 11:		Line 11:

	"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>		"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>

			"At this point we got into a hassle about the trailing wire antenna installed in the airplane, and which was intended for use on 500 kilohertz. I had previous experience with trailing wires, and it is an efficient radiator. However they are not reliable mechanically. The wire has a rather heavy lead ball attached to its end. An airplane moving at cruising speed puts an enormous strain on this wire, and the wire is subject to breaking, especially in rough air, the lead ball can break off, and you have no antenna. Airlines used them in the early days when low frequencies were used, and they soon discarded them.<ref>[[Gurr]] to [[Goerner]], 3 May 1982.</ref>

	== Using a trailing antenna ==		== Using a trailing antenna ==

Moleski at 03:15, 25 February 2009

2009-02-25T03:15:45Z

← Older revision		Revision as of 03:15, 25 February 2009
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	"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>		"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>

			== Using a trailing antenna ==

			Depending on the communication needs of any particular aircraft, the trailing antenna might be extended for the whole flight and retracted before landing. In other situations, it would make sense to extend the antenna only when it was needed.

			For those aircraft that had the capacity to transmit on multiple frequencies, the length of antenna extended could be varied so as to match the active length to the [[wavelength]] of the frequency being used at the time.

			Since Earhart had only one [[frequency\| low-frequency, long-wavelength]] band on her transmitter (500 kcs or 500 kHz), the optimum extension of the antenna was 246 feet--one eighth of the 500 kcs wavelength. The [[modifications by Joe Gurr]] were intended to allow some 500 kcs capacity on the [[dorsal antenna]] without extending the trailing antenna; when Gurr made the modifications to the radio system in Burbank before the [[first round-the-world attempt]], he left the trailing antenna system intact so that the radio operator ([[Manning]]) could decide which antenna to use.

	== Removal after [[Luke Field\| Luke Field crash]] ==		== Removal after [[Luke Field\| Luke Field crash]] ==

Moleski: /* References */

2009-02-25T01:07:53Z

References

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	<!-- Please leave this category marker at the bottom. You may add this article to other categories if you wish -->		<!-- Please leave this category marker at the bottom. You may add this article to other categories if you wish -->
	[[Category:Radio considerations]]		[[Category:Radio considerations\|Antenna]]

Moleski at 03:16, 24 February 2009

2009-02-24T03:16:45Z

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	~~"Manning was to have been the radio operator, and one~~ of ~~his jobs would be to manually reel out and in~~ the trailing ~~wire (as well as to throw the~~ antenna ~~selector switch, located in~~ the ~~aft section)" (~~[[~~Mike Everette~~]], ~~7 September 2000~~ [http://www.tighar.org/~~forum~~/~~Highlights101_120~~/~~highlights104~~.~~html Forum~~]).		== Purpose of the trailing antenna ==
			The trailing antenna on the [[Electra]] was installed to communicate on 500 kHz. "In 1937, this was the international distress frequency, employed aboard ships since the early days of radio and consequently adopted for aircraft."<ref>[http://www.tighar.org/Projects/Earhart/Bulletins/52_ElectraRadios/52_ElectraRadios.htm Electra Radios]</ref>

	[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]		500 kHz is a low frequency and therefore has a [[wavelength\| long wavelength]]. Long wavelengths require long antennas for effective transmission.

			Most accounts say that the antenna was capable of being extended 250 feet.

			== Design of the trailing antenna ==

			"A trailing wire antenna came standard with the Lockheed Model 10. [[Earhart]]'s Model 10E Special was delivered with a trailing wire antenna installed in the tail, visible externally as a small white cone protruding just below the tail nav light. ... Sometime in January or February of 1937, as part of the preparations for the first World Flight attempt, that antenna was removed and was replaced by a different type of trailing wire unit mounted in the cabin. This antenna is visible externally as a mast sticking down from the belly just forward of the cabin door. On the end of the mast is a lump which is, in fact, the lead weight on the end of the wire. Oddly, the mast protrudes from the belly at a right angle rather than at the customary shallow angle which allows the wire to play out more directly into the slipstream."<ref>[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]</ref>

			"Manning was to have been the radio operator, and one of his jobs would be to manually reel out and in the trailing wire (as well as to throw the antenna selector switch, located in the aft section." <ref>[[Mike Everette]], 7 September 2000 [http://www.tighar.org/forum/Highlights101_120/highlights104.html Forum].</ref>

	Over the years a great deal of folklore has grown up around Earhart's trailing wire antenna. A close look at photos of her airplane at various times during its brief service life (July 1936 to July 1937) and a careful review of Lockheed and Bureau of Air Commerce records disclose the following chronology.		== Removal after [[Luke Field\| Luke Field crash]] ==

	~~A trailing wire antenna came standard with the Lockheed Model 10.~~ [[~~Earhart~~]]~~'s Model 10E Special was delivered with a trailing wire antenna installed in the tail~~, ~~visible externally as a small white cone protruding just below the tail nav light. Sometime in~~ January ~~or February of 1937~~, ~~as part of the preparations for the World Flight~~, ~~that antenna was removed and was replaced by a different type of trailing wire unit mounted in the cabin~~. ~~This antenna is visible externally as a mast sticking down from the belly just forward of the cabin door~~. ~~On the end of the mast is a lump which is, in fact, the lead weight on the end of the wire~~. ~~Oddly, the mast protrudes from the belly at a right angle rather than at the customary shallow angle which allows the wire to play out more directly into the slipstream~~.		[[Ric Gillespie]], January 24, 1998, [http://www.tighar.org/forum/Forum_Archives/199801.txt Forum.]

	When Earhart wrecked the airplane in Hawaii on March 20, 1937 the trailing wire installation was, of course, crushed. Photos of the airplane in Burbank on May 20, 1937 (the day after repairs were completed) show no trailing wire in the tail or on the belly. A letter written to Earhart author [[Fred Goerner]] in 1982 by [[Joseph Gurr]] who claimed to be Earhart's radio consultant alleged that the trailing wire installation was left aboard at this time but not hooked up. All we can say for sure is that there is no evidence of the antenna visible externally when the airplane emerged from the repair shop.		When Earhart wrecked the airplane in Hawaii on March 20, 1937 the trailing wire installation was, of course, crushed. Photos of the airplane in Burbank on May 20, 1937 (the day after repairs were completed) show no trailing wire in the tail or on the belly. A letter written to Earhart author [[Fred Goerner]] in 1982 by [[Joseph Gurr]] who claimed to be Earhart's radio consultant alleged that the trailing wire installation was left aboard at this time but not hooked up. All we can say for sure is that there is no evidence of the antenna visible externally when the airplane emerged from the repair shop.

	It has often been alleged that the trailing wire was removed in Miami prior to Earharts's departure from there on June 1, 1937. Others have it removed at Darwin, Australia on June 28. As far as I know, all such accounts lack any real documentation. It appears more likely that the unit was never removed per se, but was simply not reinstalled after [[Disaster at Luke Field\| the accident in Hawaii]]. The reasoning behind such a move is, of course, speculative. It may be that, because [[Harry Manning]]'s departure from the endeavor left the flight without anyone who knew [[Morse code]], and because the trailing wire was seen as most useful on the 500 Kc frequency which was primarily a code frequency, Earhart decided that its potential usefulness did not outweigh its considerable weight.		It has often been alleged that the trailing wire was removed in Miami prior to Earharts's departure from there on June 1, 1937. Others have it removed at Darwin, Australia on June 28. As far as I know, all such accounts lack any real documentation. It appears more likely that the unit was never removed per se, but was simply not reinstalled after [[Disaster at Luke Field\| the accident in Hawaii]]. The reasoning behind such a move is, of course, speculative. It may be that, because [[Harry Manning]]'s departure from the endeavor left the flight without anyone who knew [[Morse code]], and because the trailing wire was seen as most useful on the 500 kcs frequency which was primarily a code frequency, Earhart decided that its potential usefulness did not outweigh its considerable weight.

	Amelia's attitude toward radio has been roundly criticized, and perhaps rightly so. She saw it as a luxury, not a necessity. In fact, reading her own account of the world flight, as published in the heavily edited ''[[Last Flight]]'', it's hard to find any occasion when she successfully used the aircraft's radio equipment for either voice or DF.		Amelia's attitude toward radio has been roundly criticized, and perhaps rightly so. She saw it as a luxury, not a necessity. In fact, reading her own account of the world flight, as published in the heavily edited ''[[Last Flight]]'', it's hard to find any occasion when she successfully used the aircraft's radio equipment for either voice or DF.

			== References ==
			<references/>

	<!-- Please leave this category marker at the bottom. You may add this article to other categories if you wish -->		<!-- Please leave this category marker at the bottom. You may add this article to other categories if you wish -->
	[[Category:Radio considerations]]		[[Category:Radio considerations]]