Re: What do "d" and "v" really stand for?
From: Gary LaPook
Date: 2008 Jun 20, 09:34 -0500
From: Gary LaPook
Date: 2008 Jun 20, 09:34 -0500
I wrote: >-- > Yes, I put up that web site to provide authoritive information about the process and accuracy of celestial navigation as practiced in the air in the 1937 time frame to allow everyone to evaluate for themselves TIGHAR's hypothesis. The excerpted texts were contemporary or nearly contemporary navigation standard reference works. Read through the documents, especially the single LOP landfall procedure; accuracy of sextant LOP; and accuracy of DR position topics: Greg R. wrote: Were they at least open to the material that you posted? I add: Rick didn't like me since I might have upset his applecart or broken his rice bowl but I did manage to post a lot that disputed his position and he would come up with some way to change the data (evidence) in an effort to preserve his theory. He had some other navigators that he would sic on me and I posted challenges to them to which they never responded. I am suprised now about how much I was allowd to post but some of my postings were also censored. Greg R. wrote: I pretty much soured on the TIGHAR group when the couple of items (and other questions) that I tried to post to the list apparently got "censored" by the moderator (I guess not being worthy of their time). And from looking over their website it almost looks like a fund-raising operation for the select few who actually get to go on the expeditions (with the majority of the group apparently expected to provide the bulk of the funds but only get to experience them vicariously). I add: I agree with you, it was just a business from which Ric made his living. http://www.geocities.com/fredienoonan/topics.html I wrote: and you will see that the celestial navigation using the single LOP landfall procedure had suficent accuracy to locate an island as small as Howland. Greg R. wrote: Even allowing for unforeseen winds aloft? After all of those hours without a good fix (other than maybe a running one from sun lines along the way)? I add: Yes since the technique takes into account the possible DR error due to un anticipated wind changes (in fact this makes them "anticipated") The Navigator knows the time of his last fix (we don't know when Noonan took his last fix but he knew) and you allow for the maximum possible error in the DR since that time, plus a safety factor, in determining where to intercept the LOP. Also, they were flying at night so would have been able to get good fixes. They should have been able to get a star fix within two hours of their land fall so they could have been confident of their position within 36 NM, 10 mile uncertainity in the last fix plus uncertainity due to DR of 10% of the distance flown in the last two hours, 26 NM. If you assume some earlier time for the last fix then you just add 13 nm for each hour and aim off to the side of the island by that additional amount to intercept the sun line. There is no way they would be hundreds of miles off in their DR. Even if they had DRed all the way from Lae, 2222 NM, the error in the DR should have not exceed 222NM. We know that they got fixes on a ship and at least one island while enroute so the maximum DR leg was much less and the possible error in the DR also much less. I wrote: This technique was taught to thousands of WW 2 navigators and used sucessfully many, many times by those navigators to find island landfalls. A knowledge of this technique is still required by federal aviation regulations and this knowledge must be demonstrated on the flight test for a Flight Navigator's Certificate. Look at item 34 on Appendix A to Federal Aviation Regulation Part 63 available here: Greg R. wrote: I'm surprised they still offer that certificate (realistically, does anyone even get them any longer?) - and much like the FEX (flight engineer) one I thought they'd both been exiled as historical relics of an earlier age. I add: I don't know if anybody is still getting the certificate but it is still in the regs. The Boeing 747 with INS put flight navigators out of their jobs but B-707s and DC-8s still used FNs into the 1970s. And the air force still has them and they used CN till the end of the cold war. http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=7901ef0a7d09b0a9b8b7132ad615a8eb&rgn=div9&view=text&node=14:22.214.171.124.126.96.36.199.13&idno=14 I wrote: If the technique didn't work it would not have been taught as a standard technique for many years and it would not be on the Flight Navigator test today. My "pet theory" is that they were utilizing the single LOP landfall procedure to find Howland as evidenced by their reporting being on the "157-337� LOP" which was obviously a sun line since the azimuth of the sun was 067� from the time of sunrise at Howland and remaining the same for almost an hour later, the time period of their approach to the island. Based on the known accuracy of this technique (and I have done it many times myself in flight) they should have been very close to Howland at the time of fuel exhaustion and I have no explanation for their failure to find the island. Greg R. wrote: I keep meaning to ask if maybe you were a Navy or Air Force navigator in a prior life. I add: No, but I still did plenty of CN in flight preparing for the FN certificate and while ferrying airplanes back in the '70s. Greg R. wrote: Well, the only thing I can think of that would have prevented it would be that they were a lot further off their intended course than they'd realized - do you have a better theory than unforecast winds like I mentioned earlier? I add: see above. I wrote: I do know that they are not on Nikumoro (TIGHAR's hypothesis) which is 380 NM from Howland on a true course of 169�. TGHAR's hypothesis is that they continued to follow this LOP all the way to that island (formerly, Gardner Island.) As anybody with any knowldge of CN knows, that during the three hour period necessary to fly from the vicinity of Howland to Nikumorro the azimuth of the sun would have changed significantly and there would be no LOP to follow to the vicinity of Nikumorro. Greg R. wrote: Agreed, unless that's where they ended up at their ETA because of being so far off course. I add: see above. gl -- gl On Jun 19, 11:32 pm, "Greg R."
wrote: > --- glap...@pacbell.net wrote: >> > Here are excerpts from the 1937 N.A The first page shows the >> > time of transit of the moon of the Greenwich meridian and contains >> > a "Var. per hour" column, variation? > > > > Sounds "probable" to me... > > Thanks also for the Earhart/Noonan connection - is that your site by > any chance?. Up until recently that was another pet interest of mine > (and seems like I've seen your name pop up on the TIGHAR mailing list > too). > > But after reading "Amelia Earhart: The Mystery Solved" I have to concur > with the author's conclusion that after all of those long hours from > Lae (New Guinea) they were nowhere near where they thought they were > (probably different winds aloft than they'd counted on), ran out of > fuel, and had to ditch at sea. > > Even more mind-boggling (at least in 20/20 hindsight) is that they'd > try to locate the tiny Howland Island just on DR/celestial alone > (neither of them apparently knew how to work the radio > direction-finder), and if I remember right they also weren't able to > communicate with the Itasca on the frequencies that they'd planned on > (seems like they either didn't have voice or CW capability, I don't > remember exactly right now). > > What's your "pet theory" on the Earhart mystery? > > -- > GregR --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To unsubscribe, email NavListfirstname.lastname@example.org -~----------~----~----~----~------~----~------~--~---