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Author Topic: The flight plan, magnetic course, headwinds.  (Read 470475 times)

John Ousterhout

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Re: The flight plan, magnetic course, headwinds.
« Reply #225 on: January 18, 2012, 06:39:04 AM »

gl sez: "...what they thought was a forest fire."
If they thought the smoke would rise up like smoke from a forest fire, then they would have been looking for the wrong shape, especially among scattered clouds (a quick search didn't find any evidence that they even knew the smoke would be produced, so the point may be moot).  I agree that they would have followed any clue they spotted, but I'm suggesting that a person searching for "smoke" might be looking for a rising column of smoke, like forest fires produce, rather than a trail of smoke on the water.
To Heath's point, would a trail of smoke be expected to remain visible after an hour and 20 miles?  I have no experience with smoke from boilers, only smoke from common sources, such as forest fires.


Cheers,
JohnO
 
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #226 on: January 18, 2012, 06:45:21 AM »


I believe it was Thompson that claimed the smoke stretched out for 100 miles, probably at the point when they quit generating the smoke.. Even if that is the case, it only probably stretched 12 miles at the time that they were on approach to where they thought Howland was. By 20:15, it was only 20 miles. Assuming that the actual visibility was say 25 NM, this 12 mile smoke trail was really ineffective. If they could see the trail they should have seen the island. Now had the Itasca been laying smoke for say 12 hours, then it would have stretched out the 100 miles claimed by Thompson. That would have been much more effective but it was not to be.

What is interesting looking back on it is that Thompson convinced himself that they must be North because they did not see the smoke trail. I convinced myself of that thinking that it was 100 miles long however this could not be further from the truth. I now believe that Thompson's thought process was completely flawed.
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Harry Howe, Jr.

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Re: The flight plan, magnetic course, headwinds.
« Reply #227 on: January 18, 2012, 01:40:12 PM »


The smoke leaving the stack of the Itasca would have two forces acting on it as it left the stack, the force (velocity) pushing it UP in the vertical direction and the force (velocity) of the wind  BENDING  it over  intothe horizontal direction. 

The concentration of the smoke is a complex exponential function of the height of the stack (release height), the actual height added to that by the velocity of emission, the turbulence of the atmosphere, and the distance from the point of release.

Thompson's "recollections" must be taken with a grain of salt since they are after the fact of failure and probably have a large componet of CYA.
No Worries Mates
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Irvine John Donald

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Re: The flight plan, magnetic course, headwinds.
« Reply #228 on: January 18, 2012, 10:02:23 PM »

Interesting. Is it possible, if Itasca was laying down smoke, that the smoke screened Howland from being seen by AE and FN?  This is exactly the purpose behind military smoke screens in the first place.
Respectfully Submitted;

Irv
 
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JNev

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Re: The flight plan, magnetic course, headwinds.
« Reply #229 on: January 18, 2012, 10:17:10 PM »

Interesting. Is it possible, if Itasca was laying down smoke, that the smoke screened Howland from being seen by AE and FN?  This is exactly the purpose behind military smoke screens in the first place.

Good grief - I never thought of that.  It's not something that can be proven, obviously, but it might be demonstrated that such smoke might obscure the island itself if conditions were 'right' for that - light, glare, haze or not, contrast with sea, etc.

Very interesting thought of one more thing that could be a factor in the failure to spot Howland.  I would think the flight would need to be on a fairly direct course toward the island for that to happen, though, and I tend to believe that wasn't the case - another thing that can never be proved.  Very interesting idea though, for sure.

LTM -
- Jeff Neville

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Martin X. Moleski, SJ

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Re: The flight plan, magnetic course, headwinds.
« Reply #230 on: January 18, 2012, 10:44:31 PM »

I have not found where Thompson claimed the smoke trail to stretch for 100 miles, but I may be overlooking something.

Thompson did not make that claim.

The Keane report to Associated Press from the first attempt to reach Howland says, "Shoshone will make smoke screen starting daybreak. Should be visible more than hundred miles" (record #1457).

Writing about the second attempt, Kamakaiwi noted, "Itasca was letting a big stream of black smoke out, streaming low over the water with the trade [sic]."  I presume that he meant "with the trade winds." 

I've started a section on the smoke controversy.
LTM,

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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #231 on: January 18, 2012, 11:44:23 PM »


I do not know why I missed this but on the 'Transmissions heard from NR16020' page:

http://tighar.org/wiki/Transmissions_heard_from_NR16020

It states at 17:42GMT (The 200 miles out message) "Vessel began laying down heavy smoke to assist Miss Earhart.". Is this really the case? I was under the impression that they started the smoke much earlier?

At 19:12 GMT is the "we must be on you" message. That is a time difference of only 1.5 hours. If the wind was out of the East at 8mph (not sure if that is 100% accurate) that would suggest the smoke trail was only 12 miles long. If they searched for another hour, the trail was only 20 miles long (20:13 GMT, last message).

A reporter also stated that the smoke was laying "low on the water". While Thompson noted that the smoke stretched out 100 miles, that observation is not really valid so far as AE spotting the smoke is concerned.
The deck log gives the time of the "200 mile out" call as 0614 (1744 Z) it then states that smoke was started (probably a short time later) and definitely prior to the next entry at 0645 (1815 Z) of "100 mile out" call.

gl
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #232 on: January 19, 2012, 01:09:55 AM »


- Itasca's deck log mentions laying down the smoke - but never comments on how long that actually continued.

- The smoke was observed to “stretch out for ten miles and not thinning out greatly.”

- Winds for the two hours following were easterly at 7 - 11 knots.


The deck log shows the surface wind speed at 0600, 15 minutes prior to starting the smoke, as Beaufort force 1. At 0700 is is force 2 and at 0800, 13 minutes prior to the last radio call from Earhart, it was force 3. Force 1 is 1 to 3 knots; force 2 is 4 to 6 knots; and force 3 is 7 to 10 knots. See attached Beaufort scales.
(BTW, do not go by the Beaufort scale included with the Itasca deck log, it is completely wrong, I can't understand where it came from. I was looking at it and it jumped out at me since everyone knows that force 8 is 34 knots and a hurricane, force 12, is 64 knots.) I am attaching this incorrect Beaufort table.
So the surface winds did not exceed 10 knots during this period so an average would be about 5 knots on the surface. But the wind several hundred feet up will be faster because the surface winds are slowed by friction with the earth and this is why the upper sails on a square rigged sailing ship are trimmed to a different angle than the lower sails and every pilot who has landed with a cross wind knows that the wind speed usually drops off as you get lower approaching the runway so you can reduce the cross wind correction control input.  So, it is reasonable to use 7 or 8 knots for the speed at the height of the smoke so the smoke should have blown to the west about 15 NM during the two hour period that the smoke was made and prior to the last transmission. But the Itasca continued to make smoke so it would have extended even further if Earhart was conducting a search pattern after the last transmission. But, we know that they never saw the smoke or we all wouldn't be spending our time discussing this.

gl
« Last Edit: January 19, 2012, 04:27:11 AM by Gary LaPook »
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #233 on: January 19, 2012, 01:22:19 AM »

I'm not aware of AE or FN having any experience with sighting smoke from steam-ship boilers.  Was the approach to Howland going to be their first time to see what it looked like?
At one time there was considerable interest in determining just how far smoke from ships' funnels could be seen. Several studies were done and thousands of experiments performed. I don't have the documents handy but I remember that the result was that the smoke could be seen from a considerable distance. There were two periods in particular when these studies were conducted, 1914 through 1918 and 1938 through 1945. The second set of studies were conducted under the supervision of Karl Doenitz.
gl
« Last Edit: January 19, 2012, 01:41:22 AM by Gary LaPook »
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #234 on: January 19, 2012, 01:47:13 AM »

gl sez: "...what they thought was a forest fire."
If they thought the smoke would rise up like smoke from a forest fire, then they would have been looking for the wrong shape, especially among scattered clouds (a quick search didn't find any evidence that they even knew the smoke would be produced, so the point may be moot).  I agree that they would have followed any clue they spotted, but I'm suggesting that a person searching for "smoke" might be looking for a rising column of smoke, like forest fires produce, rather than a trail of smoke on the water.
To Heath's point, would a trail of smoke be expected to remain visible after an hour and 20 miles?  I have no experience with smoke from boilers, only smoke from common sources, such as forest fires.

I was discussing this same issue with a friend on August 14, 2007 when I sent him the following:

--------------------------------------------------------

There is a brush fire burning north of Santa Barbara California and I
can see the smoke from my office in Thousand Oaks California. I
measured the distance on a Sectional chart and the distance is a
little more than 60 NM. Of course the brush fire is making a greater
volume of smoke than Itasca but it does show that you can see smoke
from this distance.

AE many not have been able to see smoke from 50 NM due to their low
altitude as I explained in a previous message but is should have been
visible at least 20 NM since that was the visibility reported by
Itasca. (Actually they reported visibility of "9" on a "1" to "9"
scale which means the visibility was at least 20 NM and may have been
a thousand NM, though unlikely, but we don't know so using 20 NM is being conservative.)

Itasca's estimate that the smoke would be visible for 40 NM might have
been optimistic but it is the only estimate that we have so we have to
accept it as being at least approximately correct., surely it exceeded
20 NM.


The main point of my post is that the smoke screen eliminated any
navigation problem associated with Noonan aiming for the wrong
coordinates for Howland. It also eliminates Long's theory that they
flew past Howland southeast bound passing to the west of Howland as
they would have seen the smoke. It leaves the most probable place for
the aircraft as too far to the northwest, more than 40 NM, under a low
cloud deck.

------------------------------------

A short explanation for why this is the case. The distance that an object can be seen at sea is limited by the horizon, the edge of the earth, getting in the way of the line-of-sight. The distance to the horizon in nautical miles is determined by the formula 1.144 times the square root of the height, in feet.  (For statute miles the multiplication factor is 1.32 or one-third more than the square root of the height.) These distances are listed in table 8 of Bowditch.

To do the calculation you calculate the distance to the horizon from the height of the object and then you add to this the distance to the horizon from the height of eye of the observer. If the smoke went up only 50 feet the distance to the horizon from that height is 8.1 NM; if it was up 100 feet then 11.4 NM; and 200 feet then 16.2 NM. The distance to the horizon from a submarine's periscope, three feet high, is only  2.0 NM  so the distance the smoke could be seen from the periscope at the various heights are 10.1 NM, 13.4 NM and 18.2 NM. The smoke at 200 feet is visible almost twice as far away as at 50 feet from the periscope.

The distance to the horizon for a plane flying at 1000 feet is 36.2 NM so the distance that the smoke could be seen from the plane for the various heights of the smoke are 44.3 NM, 47.6 NM, and 52.4 NM respectively.

This is the reason for "crow's nests" on ships. A lookout in a crow's nest 100 feet above the waterline will be  able to see more that 3 times farther compared to an observer on deck only 10 feet above the waterline, 11.4 NM versus 3.6 NM. This is also the reason that lookouts were stationed up in the periscope shears, as high as possible on a surfaced submarine, when searching for enemy ships in WW 2.

The Commanding officer of the Lexington said that the "Itasca was laying a heavy smoke screen which hung for hours." He also said that "the Itasca's smoke plume could have been seen 40 miles or more." Now the captain of the Lexington was not there at the time, so he was relying on reports from others, but the captain of the Lexington would know the capabilities and characteristics of smoke made by ships in 1937. See the Dowell report.

gl
« Last Edit: January 19, 2012, 04:28:47 AM by Gary LaPook »
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #235 on: January 19, 2012, 02:15:05 AM »

Interesting. Is it possible, if Itasca was laying down smoke, that the smoke screened Howland from being seen by AE and FN?  This is exactly the purpose behind military smoke screens in the first place.
That's because you SEE the smoke and can't see the tank or troops on the other side of the smoke that you are SEEING.

If they saw the smoke then they would have known something better than the cold blue sea was at the end of the smoke trail and would not have simply ignored it.

I used to fire obscuring smoke rounds with my 8 inch howitzers (artillery pieces) and when I was a tanker we had red phosphorous smoke grenade projectors that threw out six smoke grenades when you push the button on the ceiling of the turret to hide the tank in an instant cloud of smoke to throw off the guidance of an incoming ATGM (anti tank guided missiles.) The enemy then could not see the tank but the smoke cloud itself is highly visible. The smoke grenade projectors are those big wart like objects with many holes mounted on each side of the turret in the attached photo. (BTW, the photo is reversed right to left.)

Here is a link to a naval smoke screen being laid by two destroyers, ship not much larger than Itasca, can you see the smoke? Here's another one.

gl
« Last Edit: January 25, 2012, 06:25:13 PM by Gary LaPook »
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Heath Smith

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Re: The flight plan, magnetic course, headwinds.
« Reply #236 on: January 19, 2012, 04:10:18 AM »

Quote
I have not found where Thompson claimed the smoke trail to stretch for 100 miles, but I may be overlooking something.

Jeff, I am not sure why I thought that as Thompson did only say 10 miles in the his report. I must have read the reference that he said that they must be within 100 miles and because they did not see the smoke trail they must have been to the North-West.


« Last Edit: January 19, 2012, 10:07:55 AM by Heath Smith »
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Irvine John Donald

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Re: The flight plan, magnetic course, headwinds.
« Reply #237 on: January 19, 2012, 04:54:11 AM »

Interesting. Is it possible, if Itasca was laying down smoke, that the smoke screened Howland from being seen by AE and FN?  This is exactly the purpose behind military smoke screens in the first place.
That's because you SEE the smoke and can't see the tank or troops on the other side of the smoke that you are SEEING.

If they saw the smoke then they would have known something better than the cold blue sea was at the end of the smoke trail and would not have simply ignored it.

I used to fire obscuring smoke rounds with my artillery pieces and when I was a tanker we had red phosphorous smoke grenade projectors that threw out six smoke grenades when you push the button on the ceiling of the turret to hide the tank in an instant cloud of smoke to throw off the guidance of an incoming ATGM (anti tank guided missiles.) But the smoke cloud itself is highly visible. The smoke grenade projectors are those big wart like objects with many holes mounted on each side of the turret in the attached photo. (BTW, the photo is reversed right to left.)

Here is a link to a naval smoke screen being laid by two destroyers, ship not much larger than Itasca, can you see the smoke? Here's another one.

gl

I know what a smoke screen does and why. I used to lay smoke rounds with a mortar while in the infantry to obscure troop movements.  However, as you point out, you see the smoke. I have no idea if this was the case and the idea is unprovable but AE and FN didn't find Howland but thought they were near. If FN did his job right, and no radio messages suggest they thought otherwise, then why didn't they see Howland?  Maybe they didnt't understand what it was they were seeing. It's not called a smoke screen for nothing.  Just an unprovable idea.
Respectfully Submitted;

Irv
 
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Harry Howe, Jr.

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Re: The flight plan, magnetic course, headwinds.
« Reply #238 on: January 19, 2012, 11:28:54 AM »


Ever hear the military ditty?

When in Danger or in Doubt,
Run in Circles, Scream and Shout.
Raise the Flag and Shoot the Gun,
And cet the Words,   Well Done!!

Substitute :Steam" for :Run"  and ya can understand the "Search"
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
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Gary LaPook

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Re: The flight plan, magnetic course, headwinds.
« Reply #239 on: January 19, 2012, 12:33:34 PM »

Interesting. Is it possible, if Itasca was laying down smoke, that the smoke screened Howland from being seen by AE and FN?  This is exactly the purpose behind military smoke screens in the first place.
That's because you SEE the smoke and can't see the tank or troops on the other side of the smoke that you are SEEING.

If they saw the smoke then they would have known something better than the cold blue sea was at the end of the smoke trail and would not have simply ignored it.

I used to fire obscuring smoke rounds with my artillery pieces and when I was a tanker we had red phosphorous smoke grenade projectors that threw out six smoke grenades when you push the button on the ceiling of the turret to hide the tank in an instant cloud of smoke to throw off the guidance of an incoming ATGM (anti tank guided missiles.) But the smoke cloud itself is highly visible. The smoke grenade projectors are those big wart like objects with many holes mounted on each side of the turret in the attached photo. (BTW, the photo is reversed right to left.)

Here is a link to a naval smoke screen being laid by two destroyers, ship not much larger than Itasca, can you see the smoke? Here's another one.

gl

I know what a smoke screen does and why. I used to lay smoke rounds with a mortar while in the infantry to obscure troop movements.  However, as you point out, you see the smoke. I have no idea if this was the case and the idea is unprovable but AE and FN didn't find Howland but thought they were near. If FN did his job right, and no radio messages suggest they thought otherwise, then why didn't they see Howland?  Maybe they didnt't understand what it was they were seeing. It's not called a smoke screen for nothing.  Just an unprovable idea.
Did you operate the FOUR-DEUCE? I ended up as CHIEF OF SMOKE for an M110 firing battery.

gl
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