Highlights From the Forum
October 22 through 28, 2000
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|35||Antenna & Propagation Simulations||Bob Brandenburg|
|36||No Choice Belief Systems||Marty Moleski|
|37||Who Visited Gardner||Tom King|
|40||Re: Kites Again||Bob Brandenburg|
|41||Electra’s Vee Antenna||Marty Moleski|
|42||No Choice Belief Systems||William Webster-Garman|
For Hue Miller:
The point of my little "quiz" was to illustrate that this is a very complex issue, and that we need to reduce uncertainty to the irreducible minimum if we are to make any headway toward the truth. Making arbitrary assumptions doesn’t help. We need to make assumptions carefully derived from what we know or can logically deduce.
The point of my question was that, since we have no way of knowing the actual spectral power distribution of any harmonics radiated by the Electra’s transmitter/antenna, there is no point in guesstimating it at this stage of the analysis. I think the best approach is to assume an ideal harmonic spectrum using Terman’s numbers applied to the WE-13’s rated output power, and see what happens. If signal reception under that ideal assumption proves to be infeasible, then we’re done. But if the ideal assumption results in feasible reception, then we can incrementally lower the assumed harmonic power levels until reception becomes infeasible. At that point, there can be an informed debate about whether the range of harmonic power levels consistent with feasible reception is reasonable.
My brain-finger connectivity failed there. I intended to say "high-Q" antenna.
Yep. But we don’t know the parameter values, so it’s moot.
See discussion above.
See discussion above.
A better starting point would be to use the spectral assumptions in the discussion above, applied to the antenna gain pattern for the relative bearing and takeoff angle. We have a good model-generated approximation of the 3-dimensional antenna gain pattern at both 3105 and 6210. For example, at 6210, the net input to the antenna (after deducting resistive losses) is about 40 watts. At a takeoff angle of 5 degrees on the main lobe bearing, the antenna gain is about -15 dB, giving a radiated power output of about 2.5 watts. Applying Terman’s ideal spectral levels to the harmonics gives correspondingly lower power output levels.
I don’t have a "favorite" figure. Don’t know yet how the harmonic levels will affect feasibility. We need to proceed carefully, using the best estimates we can. Raw guesses only make things more difficult.
Since the wire antenna is on a metal aircraft, and is close to the fuselage, the fuselage is the ground that the antenna sees, so the gain pattern on the ground or in the air is essentially the same.
I’m not suggesting that at all. I’m asking a question. The antenna model shows that the transmitter antenna gain is significantly higher at the harmonic frequencies, by as much as 15 dB or more on some path geometries. The question is whether that gain improvement is enough to compensate for harmonic spectral power falloff. Dunno yet. See discussion above.
It may turn out that you are right. But whether you are or not, it’s important that we get to the answer in a deliberate, methodical, scientific way.
Maybe they will, and maybe they won’t. I have not decided what the answer is. I’ll rely on the facts to tell me that. When all the work is done, I’ll give the details to Ric for posting on the TIGHAR web site where they can be reviewed and critiqued by forum members. In a very fundamental way, my work is only the beginning of the process of finding the truth. The informed insights and opinions of forum members will be vital additions which will help illuminate the way ahead.
That issue can be addressed using the same methodology as we are applying in the case of Betty’s intercepts.
I don’t have a thesis. The facts will tell me what the answer is. Whether you pass or fail this little (ungraded) "quiz" is irrelevant.
If we’re going to grind facts, than let’s grind facts. Intuition and supposition have their place, but they don’t weigh as much as facts.
What I think about those messages doesn’t matter. What matters is whether dispassionate analysis establishes their credibility beyond a reasonable doubt. Forum members are working on that problem now.
If the Earhart mystery could be solved by using gut instinct and emotional arguments, the matter would have been resolved long ago. But TIGHAR is using the scientific method, which is a harsh task master. It’s hard, often tedious, work that requires the practitioner to suspend judgment until the facts are in. But the result is well worth the effort.
Hint: the numbers and locations of other SWLs has no bearing on the feasibility of Betty hearing the signal. It does not logically follow that if Betty heard the signals, then others MUST have heard it also.
Dunno. I was only trying to follow your argument. You seemed to be claiming that other SWLs had to have been tuning across the same frequency that Betty was listening to, and thus should have heard the same signal.
It was a rhetorical question. We know with near certainty the make and model of Betty’s receiver. It was a very good shortwave set, and we can readily get the specs when we need them.
Nothing magic about the receiver per se. But there is no point in using generic assumptions when we can use the actual specifications for Betty’s receiver make and model. The more uncertainty we can eliminate from the process, the more reliable the final result will be. As for the number of "templates", I don’t know how you define "few", but you’ll be interested to know that the manufacturer of Betty’s receiver had at least ten different electronic configurations on the market in 1937.
Just trying to understand your reliance on the assumption that other listeners must have been on the same frequency as Betty and therefore should have heard the same signal.
By the way, how is "prime time" defined for listening? Betty says she heard the signals between about 3 PM and 6 PM Florida time. I’ve been SWLing for over 50 years, and it has been my experience that "prime time" depends upon which stations I want to hear.
I’m not aware that anyone has said that there was a relationship. I take it that you claim there was no SW broadcast band that included any harmonic of AE’s transmitter frequencies. I’m not familiar with the SW broadcast bands of 1937, but perhaps someone on the forum can provide the details. Clearly, if the Maine intercept was on a frequency that was not a harmonic of AE’s frequencies (or more particularly, harmonics of her crystal frequencies) then it would be a tough sell to claim that the intercept was of an AE signal.
Well, I must defer to your perspicacity. As for me, I haven’t noticed anyone being entranced by this possibility. And I don’t know of anyone trying to justify it. Neither am I aware of anyone trying to stretch the physics, or downplaying "glaring problems", whatever that means. I am, however, aware of your a-priori dismissal of the feasibility of Betty’s reception, without application of the laws of physics and probability.
In the fullness of time, it may turn out that you have been right all along. If so, you will have bragging rights, plus the satisfaction of knowing that you guessed the right answer without having to do any real work to get there. As for me, I prefer to take the slower, plodding, deliberate, scientific path to the answer.
Janet Whitney wrote:
> Interesting that
we’re seeing complementary postings from practitioners
My view is that all humans operate with belief systems (BS).
If you have found a way to "prove everything," using no unproven assumptions, you should publish your results. Mathematicians and philosophers of science have been trying to find out how to prove everything for a couple of hundred years now and have not succeeded. Goedel’s work suggests that it is impossible in principle.
In denigrating my belief system, you merely exhibit your own.
I gave some information about my religious, ethnic, and educational background in response to some teasing from Dennis. But in my comments on "proving negatives," I made no appeal to any authority of my own or of my Church. I based my case on public sources and gave some URLs where people could read more about the fruits of others’ labors.
I make no dogmatic claims about whether or not the any-idiot-artifact (the McGuffin) can be found on Niku. The reasons for which I accept the dogma of the Roman Catholic Church are almost totally irrelevant to the question of whether the mystery can be solved next year on Niku IIII.
I love TIGHAR because it is a model of how to do sound historical research. That matters to me because so much of human knowledge and culture is transmitted through history. (You can’t prove me wrong about this, because if you try to, you will have to appeal to history to do so.) TIGHAR aims to be educational, not just about AE and FN, but about how to distinguish what is known from what is not. Hauling a bunch of fallible human observers, each with their own BS, out to a speck of land in the Pacific is the right way to test the TIGHAR hypothesis.
I’ve bet $80 so far that TIGHAR is right. I’m gonna plunk down my (OK, the Society’s) money for the 8th edition, too. In doing so, I’m making what seems to me to be a reasonable choice. I’m not staking the money on the conviction that the "Betty hypothesis" is true. If the McGuffin is found on Niku, the Betty hypothesis gains credibility in my book, though I would not think it proven by any means.
So far as I know, discussing the BS of Roman Catholicism is off-topic in this forum. I apologize for my contribution to thread drift. (But if anyone wants to know what I think on the off-topic topic, you can buy my book from Amazon for an absurdly high price. My publisher will thank you. My provincial will thank you. I will thank you.)
> ... I consider
Me, too. I believe you guys are gonna bring back the McGuffin next year.
> TIGHAR is not
a religion. We’re not that respectable. TIGHAR is a
And an addiction.
Actually, there IS some evidence of prehistoric Polynesian (or Micronesian, or Melanesian) occupation on Niku, though it’s very thin. In 1989 we found one fragmentary basalt adze bit, typical of such artifacts found in prehistoric sites throughout this part of the Pacific, on the surface in the village. Trace element analysis showed that it had almost certainly come from a known basalt quarry in Samoa. There was also a flaked core of what appeared to be andesite, found near the landing monument. Certainly not native to the island, quite likely a prehistoric artifact. Both could have been brought in by the colonists, of course, but Dan’s right, there’s extensive evidence of prehistoric occupation on nearby islands (Manra and Orona), so there’s no reason not to think that Niku was at least visited from time to time. There’s no archeological evidence that prehistoric voyagers in this part of the Pacific wore blucher-style oxfords, however. I’d guess that they were rare footgear for pirates, too.
LTM (who goes barefoot)
In a later posting I said it "might have" worked. Anything is possible.
There are some technical reasons why it might have. If y’all really want to get into that I will... but hold the thought for now. There is also the old standby, PBL "Pure Blind Luck" but obviously they did not have quite enough of that, if it did work.
With regard to the walkie-talkie/flagpole trick, all I know is, I did it, I know it worked THAT TIME. Why? I have no real clue. I can make a SWAG approximation but the point is, it worked. And if you want to hear it, I’ll explain that one too.
But that does not mean it DID work in AE’s case.
The real trick, as I see it, would have been for them to attach the kite wire to the aircraft antenna in such a way that the strain from the kite would not pull the whole antenna out by the roots... or at the very least, break the porcelain feed thru insulator or tear the mast at the apex of the Vee away.
Bob Brandenburg, what say to this?
Suppose (AHA! Supposition...! But we gotta start somewhere) one were to attach a 200, 250 or 300 foot wire, flown by a kite, to either the feed thru insulator, or to the apex of the Vee... Suppose again the average angle of the wire to the ground is 30 degrees.
With no retuning of the radio... what’s this gonna do to the radiation? And we are leaving the original Vee antenna connected too.
Remember the ground plane beneath the antenna (NOT "grounded plane" but the earth surface beneath the antenna) is darn near perfect... salt water.
Which way do the prevailing winds blow on the island? From the west? That would take the kite over the water from the reef, right?
Please, Hue and Janet... we are not grasping at straws; only looking at possibilities.
The probabilities come later.
LTM (who says nothing
is impossible to the person who does not have to do it himself) and
Out there on the reef a 300 foot kite antenna is going to be over water (or at least big puddles) no matter which way the wind is blowing.
It just occurred to me that you might have been asking me to comment on the radiation question rather than the mechanical loading problem, so here’s the radiation response.
> Suppose (AHA!
Supposition...! But we gotta start somewhere) one were to
Dunno for sure, but the antenna model would tell us. Offhand, I reckon it would be some funky (technical acronym for Fundamentally UNKown Yet) combination of a sloping long wire with a pseudo ground plane (the vee wire). My guess is that it would have a higher net gain than the vee antenna alone. Need to feed it to the model to get a useful answer.
The lengths and angle you propose seem reasonable to me. If there’s no objection, I can run those cases and see what happens.
> Remember the ground
plane beneath the antenna (NOT "grounded plane" but the
A sloper over salt water - - should be pretty good. The kicker is what the vee does to the overall performance.
Mike Everette wrote:
> The real trick,
as I see it, would have been for them to attach the kite
Excellent point, Mike. The vee antenna suspension system was able to handle wind loading on the antenna wire in the horizontal plane. But it’s not clear how well it could handle a load with a vertical stress component.
The forward mast had a guy wire running to the top of the fuselage forward of the mast. If the mast was merely riveted to the skin of the aircraft, I wouldn’t expect it to be able to handle much of a vertical load. But if it was well-anchored to a fuselage frame, it might be able to handle the kite load.
But hooking the kite wire to an arbitrary point on the vee wire could put an intolerable catenary stress load on the insulators at the ends of the wire.
LTM, who thinks
too much stress is a bad thing.
Janet Whitney wrote:
> ... The Itasca
did copy Earhart from at least 200 miles away on 3105
What, if anything, might be deduced from the fact that Lae did not hear anything on 6210 until AE was four hours out and that the Itasca never heard anything from her on 6210? Is it normal for 6210 to have that kind of "cone of silence"? (I refer, of course, to Maxwell Smart, since I know more about that program than antennas.)
> Any discussion
of what we hope to find on Niku would be entirely
I can list some things that I hope you might find:
5. pirate treasure
Cult: Definition 5 of Merriam-Webster’s Collegiate Dictionary, Tenth Edition, 1994: "a. great devotion to a person, idea, object, movement, or work...b. a usually small group of people characterized by such devotion."
Now we just need to figure out where to build the compound.
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