Highlights From the Forum
October 8 through 14, 2000
|35||Betty’s Story vs. Photographs||Bill Carter|
|36||Re: Pilot Question||Tom Van Hare|
|37||Re: Japanese Broadcast Stations||Judy|
|38||Re: LOP||Randy Jacobson|
|39||Re: LOP||Tom MM|
|40||Re: Betty’s Intercept||Mike Everette|
|41||Re: Pilot Question||Skeet Gifford|
Maybe I’m confused but it seems that about a month ago, there was a lot of discussion and debate about whether the pitot and the belly antenna on the bottom of the Electra sustained damage on the runway at Lae. If that damage in fact occurred and it affected AE’s ability to establish radio contact with Itasca (which was in the general vicinity of Howland before AE’s disappearance) how is it possible that (assuming AE was able to land the plane) a transmission from AE could be received in Florida? Well, let’s assume for a second the belly antenna wasn’t damaged at Lae in spite of the photographic evidence. What are the chances AE could land the Electra on a reef or beach without damaging the pitots or belly antenna? Maybe the Forum members with a much better understanding of radio signals than I have can help piece this together.
The damaged belly antenna and pitots would have no effect on the aircraft’s ability to transmit which was accomplished via a wire antenna on the top of the airplane. The lost belly antenna was a receiving antenna. Some contend that reception could also be accomplished over the antenna on the top of the airplane. Others (myself included) think that reception (in the absence of the belly antenna) would rely upon the DF loop over the cockpit. In either event, the accident at Lae would have no effect on the post-loss radio question.
Birch Matthews wrote:
> I have a question
for piston engine pilots on the Earhart Forum.
Ok, to start off this discussion topic, I think it would be important to discuss these issues from a more general perspective. Therefore, with Ric’s permission, I will talk about this one from the layman’s perspective for those who are not pilots out there.
Generally speaking, there are a lot of issues that come into play here. When looking at very long distance, endurance flights, the most critical factors are going to be the engine setting, maintaining minimum rpm while running at higher manifold pressures (often called "over square"), and the winds that vary at different altitudes.
(To address the modern pilots in the forum, running an engine "over square" is not a bad thing, in actual fact, from an endurance and engine maintenance perspective, it is quite rather the opposite -- just check with a good maintenance guy and he’ll confirm this -- and if it is in the POH, then you can run it that way, despite the common wisdom....)
However, when you’re flying a relatively slower airplane like the Electra, "hunting the wind", an old Pan Am Clipper term which means looking for a favorable tailwind or minimum headwind at the least by climbing through various altitudes, may be far more important than the engine setting.
Now think about the fact that the winds commonly vary in both direction and windspeed depending on the altitude. In the old days, when the planes were slower, the winds played a very big role in getting there -- when you have a top speed of 400 kts, a difference of 30 or 40 kts in windspeed are not proportionately very significant. However, when you’re flying a plane that tools along at 80 kts, that can mean nearly doubling your time in the air if you’re facing a headwind of 40!
Now, imagine yourself in a Lockheed Electra. The plane cruises nicely at 140 kts and runs for about 8 hours at that engine setting. If you push the power, you can maybe fly at 150 kts and run for 7 hours. If you throttle way back to maximum engine efficiency, maybe you will fly at 125 kts for perhaps 9 hours.
Now, we’ll imagine that today you’re facing a tailwind of 20 kts down low. However, it switches around to a 40 kts headwind up high. Being a macho man of a pilot, you believe that flying high and fast will always get you there faster -- oh, so wrong, as you will see....
So, you push the power in and fly up high. The result is a ground speed of 110 kts (150 kts speed minus that 40 kts headwind) and a higher fuel burn. Amelia Earhart, however, might have flown at her best efficiency engine settings down low. That would yield a ground speed of 145 kts (125 kts speed + 20 kts tailwind).
Now add in the number of hours of fuel on board depending on the engine setting (the faster you push it, the more fuel you burn), and you will see some interesting numbers.
Flying low and slow, using that good tailwind, the smarter Amelia Earhart in this example would fly fully 1305 miles (145 kts ground speed multiplied by 9 hours of air time). The fly high and fast macho man would end up going only 770 miles (110 kts ground speed multiplied by 7 hours of air time).
So if your destination is an island 1,000 miles away, flying smart means the difference between crashing in the ocean or arriving with two plus hours of fuel on board -- enough time to circle around looking for that little dot of land somewhere out there and maybe even fly to an alternate destination!
Returning to reality, to really examine this issue for Earhart’s particular situation, it would take solid information about winds along her route of flight (not known with any certainty), her actual power settings (potentially could be surmised), the exact engine specifications on her twin radial engines (I believe the Kelly Johnson numbers have been discussed before here), her planes performance and endurance at each power setting, and much more, those being the most critical items. Some of this is known, some of it is not.
What could follow on this topic could be a long and very involved discussion that reaches no solid conclusions. Mr. Long in his book seems to find it quite acceptable to make educated guesses about power settings and projected winds aloft, as well as guessing what altitudes Earhart may have flown.... That’s a lot of guesswork to depend on if you are going to say that she ran out of gas at a particular moment in time. For my part, I can’t remember ever flying a single long distance flight without adjusting my power settings at least several times.
All of this aside, suffice it to say that Noonan and Earhart would have done their best -- and they were pretty damn good by the standards of those days.
Thomas Van Hare
Re: were the Japanese picking up AE’s broadcasts and did they understand her name, and English? In 1937, the Japanese were in preparation for their big military blowout..their objective....to own and control all of South East Asia which would have meant owing and controling over 1/2 of the world’s population. And, in 1937, Japan’s military establishment was angry with the US because we would not send/supply them with oil/fuel to aid with their munitions buildup (no oil in Japan). It follows that the Japanese military intelligience was ’listening’ very closely to everything coming out of the USA, (they didn’t want us to give them any problems) and certainly their intelligence officers knew English. Of course they did. They also knew when the Americans turned tail after 18 little days of searching for AE/FN and went home. And where would u suppose the Japanese military might go after the Americans went home.....remember, at one point in her last flight, Earhart was only 100 miles off shore from one of those Japanese occupied islands with munitions buildup. The Japanese could have swum to Gardner, or taken a row boat.
As Cary Grant supposedly once said, "Judy, Judy, Judy...". Your impression of Japan in 1937 is pure Hollywood. At the time of the Earhart disappearance Japan was hardly the aggressive monolith it was to become in later years. The political power of the militarists had not yet become firmly established ( a general election in June showed strong continued popular support for a parliamentary government).
It was not until July 7th that the army, in a successful effort to undermine democratic leanings at home, staged the Marco Polo Bridge incident which sparked war with China. Japan, at that time, was still trading freely with the United States. The freezing of Japanese assets in the U.S. and the embargo on oil sales didn’t happen until 1940. No "munitions buildup" had yet begun in the mandated territories in 1937 and Earhart (assuming she was on course) never came closer than about 500 miles to any Japanese island. If she was on Gardner she was a thousand miles from the nearest place controlled by the Japanese. That place -- the oft mentioned Mili Atoll -- was nothing more than a few Marshallese fishing villages with some Japanese commercial supervisors.
Answers to Mike Muenich’s questions:
>1. Is a LOP altitude
sensitive; i.e. If FN is over Howland on July 3rd at
Yes, but only at a 0.1 degree level.
>2. Is a LOP time
sensitive; i.e. if his navigational chronometer broke on
Most definitely, as the LOP depends upon the time of day. LOPs change most rapidly during noontime, but this particular LOP was at sunrise, and was stable for approx. 1.5 hours.
>3. Is a LOP date
sensitive; i.e. if FN took a LOP on July 3rd, would it
Yes, but only slightly at this time of the year.
>4. Can a bubble
octant and a sextant perform all of the same functions;
LOP is derived from a bearing relative to true north to a target, and is usually extracted from a detailed table. It is where that LOP lies that is obtained from using a sextant-type device. Sextant, octant, and bubble octant, if used correctly, are equivalent for determining positions.
>5. Depending on
your response to #4 above, is it possible that FN could
LOP is not directly observed, but is inferred. Latitude is easy to measure; longitude requires precise time.
>6. Depending on
your response to #2 above, could a time error cause the
>7. Depending on
your response to #3 above, could the progression in dates
Yes, but I don’t see why this is relevant to AE’s navigation or where they think they are.
>8. Assuming all
of FN’s equipment is in working order and he is accurate,
Yes, probably each day of the year, but the time it happens will vary from day to day in a regular fashion.
>9. Would the change
in altitude from 2,000′± MSL to 10′± MSL cause
Not measurable within normal precision.
>10. If FN was severely
hurt, could he talk AE through the process of
Unlikely, but possible if she knew mathematics and what she was doing. It’s tough even when the books are right in front of you.
>11. Is it possible
that only a LOP could be calculated with some of the
LOP could be inferred directly from the tables with reasonable accuracy.
For Mike Muenich’s questions:
Well, I’ll try to take a crack at these. Some of these relate to LOPs in general, but others can only be answered if it is understood that a single celestial body is being discussed. In those cases, these responses relate to the sun only -- not to the moon, stars and planets. It became clear while typing these that a lot of simplification had to take place. Hope this does not just make things worse.
I have to say that once the aircraft was down, an LOP would not be the thing to report to the world (coordinates or island name would be the thing) unless you didn’t know where you were, but were trying to describe how you got there. In that case, you would expect only one leg of the LOP to be broadcast (ie, "we flew on 157 true for about xxx miles on an LOP thru Howland." At least that would specify a narrow search band. Anyway, Q & A’s follow.
1. Is a LOP altitude sensitive; i.e. If FN is over Howland on July 3rd at 8:00 and at an altitude of 1,500 feet MSL, would the LOP be different if he were on the ground at the same time and position?
2. Is a LOP time sensitive; i.e. if his navigational chronometer broke on landing (crashing) and he was unable to get a reliable time hack, would an error of several minutes on his wristwatch affect the LOP?
3. Is a LOP date sensitive; i.e. if FN took a LOP on July 3rd, would it change on July 8th at the same time and place?
4. Can a bubble octant and a sextant perform all of the same functions; i.e. can an octant produce each of a LOP, Lat. and Long; can a sextant?
5. Depending on your response to #4 above, is it possible that FN could only calculate a LOP and not Lat. or Long.?
6. Depending on your response to #2 above, could a time error cause the creation of a LOP of 158/338 for Gardner?
7. Depending on your response to #3 above, could the progression in dates from July 3rd to July 6th, 7th, 8th etc cause a change in a LOP?
8. Assuming all of FN’s equipment is in working order and he is accurate, is there a date on NIKU that’s its LOP is 158/338?
9. Would the change in altitude from 2,000′± MSL to 10′± MSL cause a shift in the LOP?
10. If FN was severely hurt, could he talk AE through the process of calculating a LOP with either a sextant or an octant and what would the theoretical amount of error be; would he be equally able to talk her through a Lat./Long. equation?
11. Is it possible that only a LOP could be calculated with some of the equipment at hand and not an accurate Lat./Long. by either AE or FN?
That’s all I have
to say ’bout that,
>Did Band 2 on the WE 20B not cover from 550 to 1500 KHz?
Yes it did, on the standard 20A (local control) and 20B (remote control), but not the modified 20B that AE had.
In order to reach the 500 KHz marine distress freq (and this was the only universal distress freq used in 1937), the tuning range of the receiver was modified. The Band 2 coverage was "fudged" downward.
Because the low end was moved, the high end of the AM broadcast band was lost. This is a result of the shifting of the tuned circuit either by placing "padder" capacitors across each of the Band 2 coils, or by replacing the standard Band 2 coils with others having greater inductance.
I do not know which method was used. Either will work, but the replacement of the coils would be preferable. Since we are talking about Western Electric, who normally did things in a very thorough manner, I’d sort of bet on that method; but then again, seeing how they modified the transmitter for CW -- a sort of Rube Goldberg arrangement -- who knows?
Nonetheless, the tuning range was indeed shifted downward.
The published specs for the 20AA and 20BA, which are the models for the range-modified units, list Band 2 as 485-1200 Kc (KHz). I may have said 1250 yesterday; sorry, that was a typo.
So if KGMB was transmitting on 1320 in 1937, she could not hear that station on the WE receiver.
Ergo... second receiver. Unless they had some kind of emergency receiver, like a "portable" full of tubes and heavy "A" and "B" batteries.
I am going to have to research this... for some reason I thought, all along, that KGMB used 630 KHz at that time, and just never looked it up. For a station whose primary coverage area includes all the Hawaiian Islands, a lower freq would certainly give better ground wave coverage over a wide area day and night. Also, the high end of the AM band (considered to be above 1000 KHz, and especially above 1200) is mostly the province of "local" stations, many being low power peanut whistles (1 KW or less). 1320 KHz, in fact, is a frequency populated by many such outlets in the modern era.
(Yes, I know, there are notable exceptions to that, including WCKY Cincinnati, WCAU Philly, etc etc etc.)
LTM (who likes them
newfangled transistor radios) and
Whadya wanna bet you find that 1320 is not the frequency that KGMB was using in 1937?
The simple answer to Birch Matthews’ question is, no, it was not common practice to step-climb piston-engined transport aircraft as gross weight decreased. Other factors were of far greater importance in determining cruise altitude.
For UNPRESSURIZED aircraft:
1) Cruise altitudes are necessarily limited due to oxygen requirements.
2) If possible, altitudes were selected to avoid visible moisture and temperature combinations that would require use of carburetor heat (less than 15 degrees C). Reciprocating engines are significantly less efficient when using carb heat--but much more efficient than they would be if the carburetor iced up .
3) The airplane (and the pilots) are less efficient in turbulence, so selection of an altitude that was smooth was more than just a "passenger comfort" issue.
For PRESSURIZED aircraft:
1) Speed was the overriding consideration for the airlines. Therefore, cruise altitudes were determined by the altitudes offering the best True Airspeed at maximum cruise power. This occurs in high blower in the low-to-mid 20s.
2) Avoidance of turbulence and carb ice were still important.
Birch, if you would like any more information, I’d welcome an excuse to dig into my library of old flight manuals.
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