Paddle blade P-47 and P-38J

FLYBOYJ said:

Point made here, it the real world combat pilots are going with what's in the POH, some may get more out of their mounts, some a little less (I'd bet not by much), but bottom line the POH (or -1) is the bible.

Click to expand...

This is true, the POH is designed to be achiveable by any aircraft on the line with an average pilot. BTW thats why I added the note on the graph it is almost identicle to the POH for the P-38J/L in military power. Remember to, the POH does not include WEP numbers probably because they can vary so much.

FLYBOYJ said:

If tests were done at places like Wright Patterson that got different data, someone felt it wasn't significant enough to place in the -1.....

Click to expand...

Actualy, I belive, in many cases it was factored in to create the average for the POH. Something else that must be considered is air quality - density, moisture content ect. the chart above being performed by Lockheed will be on the west coast where ideal flying conditions exist. Many of the AAF tests were at Eglin Field where conditions vary wildly and humiditity is on the average higher than other locations. With the P-38 or other turbocharged aircraft this can affect turbo speeds and effectiveness greatly.

FLYBOYJ said:

And as usual, great info JJ!! I love the page that shows the relationship tp MP and RPM - REMEMBER THAT GUYS!!!! It torques me to hear conversation about "boost" when no mention is made about engine RPM - they go hand in hand!!!!!!

Click to expand...

This is criticle to, as a turbo puts out pressure in relation to the heat content of the exaust fed into it - the harder the engine works the better the turbo works. The prop pitch can increase/decrease manifold pressure due to the workload required of the engine for a particular rpm. This is why the P-38 was more fuel efficent with Lindbergs lower rpm higher manifold pressure cruise technics than it was with the standard cruise procedures.

wmaxt

There are several Allison technical notes clearing the P-38 for 64" Hg on 100/130 after 1943.

The problem is that the Allison V-1710-111/113s on the L model had were just rubber stamped with the same engine rating at as the 89/91s, when in practice they were much more powerful. The 111/113s introduced a much more solid 12 weight crankshaft, over the 6 weight crankshaft which allowed them to run at higher revolutions for longer periods with lower crankcase and bearing pressures.

Full War Emergency power of 1,725 could only be achieved at 64" Hg @ 3200 rpm with 100/130 fuel. However, there were tests of P-38s with 89/91s with 150 grade at 70" HG and eventually the 8th AAF increased the WEP power rating up to 66" HG with 150/100 grade.

wmaxt said:

FLYBOYJ said:

Point made here, it the real world combat pilots are going with what's in the POH, some may get more out of their mounts, some a little less (I'd bet not by much), but bottom line the POH (or -1) is the bible.

Click to expand...

This is true, the POH is designed to be achiveable by any aircraft on the line with an average pilot. BTW thats why I added the note on the graph it is almost identicle to the POH for the P-38J/L in military power. Remember to, the POH does not include WEP numbers probably because they can vary so much.

FLYBOYJ said:

If tests were done at places like Wright Patterson that got different data, someone felt it wasn't significant enough to place in the -1.....

Click to expand...

Actualy, I belive, in many cases it was factored in to create the average for the POH. Something else that must be considered is air quality - density, moisture content ect. the chart above being performed by Lockheed will be on the west coast where ideal flying conditions exist. Many of the AAF tests were at Eglin Field where conditions vary wildly and humiditity is on the average higher than other locations. With the P-38 or other turbocharged aircraft this can affect turbo speeds and effectiveness greatly.

FLYBOYJ said:

And as usual, great info JJ!! I love the page that shows the relationship tp MP and RPM - REMEMBER THAT GUYS!!!! It torques me to hear conversation about "boost" when no mention is made about engine RPM - they go hand in hand!!!!!!

Click to expand...

This is criticle to, as a turbo puts out pressure in relation to the heat content of the exaust fed into it - the harder the engine works the better the turbo works. The prop pitch can increase/decrease manifold pressure due to the workload required of the engine for a particular rpm. This is why the P-38 was more fuel efficent with Lindbergs lower rpm higher manifold pressure cruise technics than it was with the standard cruise procedures.

wmaxt

Click to expand...

AGREE!!!!

Jabberwocky said:

There are several Allison technical notes clearing the P-38 for 64" Hg on 100/130 after 1943.

The problem is that the Allison V-1710-111/113s on the L model had were just rubber stamped with the same engine rating at as the 89/91s, when in practice they were much more powerful. The 111/113s introduced a much more solid 12 weight crankshaft, over the 6 weight crankshaft which allowed them to run at higher revolutions for longer periods with lower crankcase and bearing pressures.

Full War Emergency power of 1,725 could only be achieved at 64" Hg @ 3200 rpm with 100/130 fuel. However, there were tests of P-38s with 89/91s with 150 grade at 70" HG and eventually the 8th AAF increased the WEP power rating up to 66" HG with 150/100 grade.

Click to expand...

Heard the same thing - the one thing you didn't want to do is exceed boost at the given RPM setting for the given fuel used - it will detonate and probably blow up the intercooler and ducting....

Sal good to see you back… Nice chart which I see seems to confirm my climb data from where we left off; wish you had posted this then…

??? I'm not sure what you're talking about. Have I ever indicated that the paddle bladed prop P-47D could not do 7 minutes to 20,000ft, or alternatively, pull the climb rate indicated?

Incidentally, the internal fuel capacity of the P-38J was 416 gallons so the 300 gallon fill in the P-38J Airplane, AAF, No. 42-67869 data you provided is less than 75% fuel capacity. I know you aren't advocatiing tests with less than full internal fuel

Sal I refer to >>
Edited from ( http://www.ww2aircraft.net/forum/about1116-0-asc-80.html ) Sal Monella Posted: Wed Nov 23, 2005 9:33 pm: "…Your data on the climb rate of the D-23, however is still in error, It was 2,920fpm. It had a greater climb rate than the D-25 because the D-25 was burdened with an extra 100 gallons of fuel in its internal tanks."

Below I repost your table; I see a greater accuracy in my number, do not see any handicap other than speed related to your statement of the added burdens of the -25 models.

With regard to my advocating of the test, yeah I do. Not because they 'correctly' loaded the aircraft to what I would consider 'combat weight', but because the aircraft will perform as they stated, loaded as they stated; they stated what they believed combat weight was, going further to recommend that all further tests be 'run' at combat weight.

What this statement really implies, sad to say, is that there was no standard method in the testing of aircraft as run by the Flight Test Engineering Branch at Wright Field before or during Feb 1944. So they started a dialog towards a standard, a combat weight standard. I can not conclude from reading this what reason they truly had used in their choosing of 300 gallons. I can only assume, once again I must use my 'judgment', they arrived at this vale by doing one of the following… They neglected to fill the 'outer wing tanks'; or 'figured' they would be dry during combat. I also have to consider the mentioning of an 'automated observer' and 100 lbs of ballast in the nose, can this explain the 110 gallon offset. More scary, is that you indeed have a very valid point forcing this conclusion to my attention, maybe they actually were testing a P-38-H, the numbers posted are closer to this aircraft. A quick check of the serial number at Joe Baugher's site, not that he is always the last word, shows this aircraft as a J model. Whew!!! But you still have a point, so last but most probable of all, 300 gallons is close enough for 'military' work. If true, this is a fine attitude practiced the FTEB… NOT!!!

This is not how my table's figures were generated, nor do I agree with the FTEB @ WF with regard to the definition of combat weight, heck combat weight is not defined this way in the '38 manuals either.

Last few points, I condone this test not because it is perfect, but because the primary motive was not to 'commercially promote' one type's ability over another, or to secure a contract; but to determine what the aircraft's true ability was at climbing and going fast.Then using this collected comparative 'combat weight' data they could view specific aircraft design 'strengths' weaknesses', to promote their 'proper usage'. Cold pilot-less data; just what I need for simming; just what we need to determine what truly was the 'empirical' best machine at the roll of ....

Jabberwocky, can you direct me to some of this Allison info... Please.

I did indeed state the portion of text you excerpted. I looked back at the data I relied on and noticed that it was for 10,000ft. My bad. As you yourself are aware, the D-23 and D-25 did in fact have a 100 gallon difference in internal fuel capacity.

100 gallons of avaiation fuel weighs about 600 pounds. The bottom line is that at 16,597lbs, she was 800 pounds below combat weight of 17,400lbs

And Jon, again, you said: Sal good to see you back… Nice chart which I see seems to confirm my climb data from where we left off; wish you had posted this then…

And again, where exactly did you ever indicate your climb data for the D-23 with a climb rate corresponding to my chart posted on this thread?

You did say the following below at - http://www.ww2aircraft.net/forum/viewtopic.php?t=1116&postdays=0&postorder=asc&start=80

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

You know, before I start, everything with you is where does your data come from. I post where it comes from all the time. I have nothing to hide… However, once again Sal, for you, I'll go backwards…

47D-23 Prop Climb:

http://www.xs4all.nl/~fbonne/warbirds/ww2htmls/repup47.html#repup471
Although specifically for D-22 (This site asks that nothing be reprinted) some climb rate Specs.

http://home.att.net/~jbaugher1/p47_4.html
Joe puts the climb rate at 2750ft/min, but >>> "Beginning with production blocks D-22-RE and D-23-RA, a larger (13- foot diameter) paddle-bladed propeller (either a Hamilton Standard Hydromatic 24E50-65 or a Curtiss Electric C542S) was fitted to make full use of the additional power provided by water injection. It added 400 feet per minute to the climb rate, but during landings and takeoffs there was only a scant six inches of clearance between blade tips and the ground. Takeoffs and landings must have both been hair-raising."

Hey Sal, Thanks.

Edited from ( http://www.ww2aircraft.net/forum/about1116-0-asc-80.html ) Sal Monella Posted: Wed Nov 23, 2005 9:33 pm: "…Your data on the climb rate of the D-23, however is still in error, It was 2,920fpm. It had a greater climb rate than the D-25 because the D-25 was burdened with an extra 100 gallons of fuel in its internal tanks."

Sal, your referral of my data goes back to my post: Mon Nov 21, 2005 12:53 am ( http://www.ww2aircraft.net/forum/about1116-0-asc-60.html ) which asked you download rev 4.1, or v5.6 of my fighter comparison table. The 3120 FPM derived by calculation climb rate is posted there as it can be found in my 'latest' revision of those tables, I invite you to download here ( http://www.ww2aircraft.net/forum/viewtopic.php?t=962&postdays=0&postorder=asc&start=520 ) at the top of the page.

Our P-47 debate raged for a time; during the lapse I started to gather more and more 'actual pilot manual' 'test' data that supported my 'calculations'.

My conclusions on the fighter comparison tables can be found here ( http://www.ww2aircraft.net/forum/viewtopic.php?t=962&postdays=0&postorder=asc&start=540 ) JonJGoldberg Posted: Wed Dec 14, 2005 1:34 am.

As for the P-47 thing, you know where to go to review this, and if you agree, as I would prefer, we should return there continue this 'sidebar' as it relates to this thread, as I believe the fuel increase in the -25 to be 65 US gallons, moving from 305 to 370 gallons. One of my recently acquired flight manuals cover the B, C, D, G series aircraft before the Bubble, which was the other 'L' modification Incorporated into '47D-25-RE. I believe the 'L' mod was performed on a '47D-20-RE pulled from the line. Anyway I have no way of 'knowing' for sure that the 390 lbs + or - that the 65 gallons of fuel represents, may have been largely off set by the reduction of mass due to the cutting down of the fuselage, the removal of the 'bird-cage', at least until the appearance of the -27-RE, which added the dorsal extension; as my other manual covers only the N, the install of the bubble increased drag.

Ah yes. But your data DID NOT then indicate 3,120fpm now did it? It was, of course, later changed. Clever Jon.

You are correct on the fuel increase of 65 gallons. My error.

Sal, come on now, you are telling me I went to all my posts and changed what was there... Updated the attachments... Left no edit markers... Damm I am clever 8)

Sal, your referral of my data goes back to my post: Mon Nov 21, 2005 12:53 am ( http://www.ww2aircraft.net/forum/about1116-0-asc-60.html ) which asked you download rev 4.1, or v5.6 of my fighter comparison table. The 3120 FPM derived by calculation climb rate is posted there as it can be found in my 'latest' revision of those tables, I invite you to download here ( http://www.ww2aircraft.net/forum/viewtopic.php?t=962&postdays=0&postorder=asc&start=520 ) at the top of the page.

Your fighter comparison table was subsequently changed after our discussion. You will note that the table is a .pdf and not part of this forum.

Perhaps clever was a bit too optimistic of a description.

Sal Monella Posted: Sun Mar 12, 2006 3:59 am

"...Your fighter comparison table was subsequently changed after our discussion. You will note that the table is a .pdf and not part of this forum.

Perhaps clever was a bit too optimistic of a description. "

Sal you believe what you wrote?
You are being a bit .

When you, or I , or anyone attaches something to a 'post' at this site, a copy is placed in storage within this site's server, and becomes the 'master file' from which all requests may be satisfied. In order for you, or I, or anyone to 'change' this 'master file' we must gain access to it. Access by my level of membership, I'm not admin, is gained by opening the post to edit it, leaving an edit marker. I've done this once, to add my fighter comparison chart to my posting appearing at the top of a page, as can be evidenced here ( http://www.ww2aircraft.net/forum/viewtopic.php?t=962&postdays=0&postorder=asc&start=520 ). Edit markers seem not to appear until someone else posts.

This is obvious, but, anyone in admin may correct, or change what I wrote above.

Lastly, as this is boring me now, you and I disagree on the climb of the N as well, yet that figure is as unchanged within the tables as my figure for the D… Odd .

Jon is infact correct....

Nice Henschel 129 pic Lesofprimus.

Henk

No, I'm not wrong. When you post a link to a web page or .pdf, the system records the link. If that link thereafter becomes defunct, you cannot revive the web page or .pdf that the link was to by downloading it from the "master file" as you say. Therefore, when you posted your thread with a link to the .pdf, the .pdf as linked at that specific moment was not frozen in time in the system. (It's a good thing for you too because we would be able to go back and establish that your 3,120fpm figure was not part of the .pdf back then)

Jon, we all throw around a lot of facts and data on this site. You need to be able to admit your mistakes. Already twice on this thread I have admitted to errors.

1) Erroneously relying on 10,000ft altitude

2) Asserting that the difference in fuel was 100 gallons when it was really 65

I have no problem admitting to errors on my part Jon. You do. I recall the colorful story you spun to support your assertion that the P-47N's length had changed from the preceeding D model's in order to maintain the center of gravity. That was classic! (Which emoticons should I insert here?)

Sal Monella said:

100 gallons of avaiation fuel weighs about 600 pounds. The bottom line is that at 16,597lbs, she was 800 pounds below combat weight of 17,400lbs

Click to expand...

The 800lbs you mention is for the L model with the extra fuel, boost pumps, hydralic ailerons, added heat ducting for the cockpit. The J-25 had some of this but not all of it and so was still lighter than the L.

The early P-38Js did not have the wing leading edge fuel tanks. The leading edge tanks were intermittently installed starting with the P-38J-10 and were not standard on all aircraft until somewhere between the J-15 and J-25. So that machine may have only hat the standard ~300gal capacity. That aircraft also had 100lbs ballast extra in the nose that was removed as it was found that the CG was fine without it.

There is also a question of the exact qty of the leading edge fuel tanks, some sources report 62gal and some report 55 gal. Not even Lockheed sources are difinitive, probablities are: they tried both, rated a 62gal at 55gal to allow for expansion or the reduction is a result of the boost pump installation in the J-25 and L models and/or a combination of the above.

Both Lockheed and Allison certified the 111/113 engines for 64" and 1725hp and the AAF sent out a field order allowing it. However it is not clear that the AAF ever made it offical and there is no evidense that it was ever approved overall. Both Allison and Lockheed worked in the field directly with the pilots and ground crew so it was probably used where it was reasonable and pilot comments confirm it happened on occasion.

wmaxt

Sal your description of how web servers work I was not able to fully follow, but the attachments are frozen in time, as you state in the added in the brackets, and stats are visible for all to see, all of my old links (revisions, attached .PDF-s) still work, display different documents; they contain all of my original, as you claim, erroneous, that are now good cause I changed them numbers. You may find them here… Notice that each file is located a different location, locked each in its own WW2aircraft vault. This is a major reason some of us post to servers like these. If it didn't work this way there would be no 'archive' to reference, therefore no point.
Rev 4.1 ( http://www.ww2aircraft.net/forum/download.php?id=20848 )
Rev 5.6 ( http://www.ww2aircraft.net/forum/download.php?id=21303 )
Rev 5.6 corrected shading ( http://www.ww2aircraft.net/forum/download.php?id=21522 )
Rev 5.6 top of page 27 ( http://www.ww2aircraft.net/forum/download.php?id=21828 )


I do not make them much due to the time I put into my posts; however my posts contain 'admissions'.
Recent examples:
{( http://www.ww2aircraft.net/forum/about3820-0-asc-0.html ) Posted: Sun Feb 19, 2006 11:29 am}
{( http://www.ww2aircraft.net/forum/about3703-0-asc-100.html ) Posted: Sat Feb 04, 2006 1:26 am}
Relevant examples, there are a few here starting with:
{( http://www.ww2aircraft.net/forum/about1116-0-asc-100.html ) Posted: Thu Nov 24, 2005 3:16 pm}
I'd be happy to concede to you, or anyone, about any error that I have made, once it is brought to my attention, as this one of the best 'learning' methods I know of.

Sal why do you really want to go back to the end of November and the 2" question? I hope at the end of this there is something more meaningful as a reward for you, other than my admission of fabrication, or what I see as an admission of an error… Yes, my memory can be flawed from time to time (For example I thought wmaxt had mentioned the Allison rated to 66"Hg, in fact he posts 64"Hg; by the way sorry wmaxt…). Before I do this; to the other members here I'd like to say sorry to put you through this; I'm too easily taken in for a man of 45; I should be ignoring Sal's most recent post, entirely, not trying to help him.

My 1st post which started the 2" discussion…
Edited from JonJGoldberg Posted: Sat Nov 19, 2005 10:31 pm
( http://www.ww2aircraft.net/forum/about1116-0-asc-40.html )
"…Fuel in the wings, and the fuselage extension did not benefit the '47's aerobatic performance; although the increased power, fuselage extension (2"), wing air flow improvements did increase its speed."

Sal's 1st direct comment…
Edited from Sal Monella Posted: Sun Nov 20, 2005 2:50 am
( http://www.ww2aircraft.net/forum/about1116-0-asc-60.html )
"Jon, I think you're looking at a typo as far as the dofference in length. I have never seen any lengthening of the fuselage referenced in any publication. If you can point out a reference to the lengthening of the fuselage that would support this length discrepency, I would concede…"

Edited from JonJGoldberg Posted: Sun Nov 20, 2005 5:04 pm
( http://www.ww2aircraft.net/forum/about1116-0-asc-60.html )
"…I can not 'quickly' find reference as to why there is a 2" discrepancy in the data between P-47D N lengths. You may be correct, they may indeed be typos. My memory; however seems to tell me that it was done to reset CG due to the increased mass behind CG of the wheels. However I repeat, unlike the 8" extension between B C, where documents are easy to find, I can not find a document with a reason. Wish I could ask Alexander Kartveli."

Edited from Sal Monella Posted: Sun Nov 25, 2005 2:50 pm
( http://www.ww2aircraft.net/forum/about1116-0-asc-100.html )
"…You read a typo (I think I was being too generous. I think it was probably just another instance of garbage data) regarding a difference in length between the "D" and "N" models and then suddenly have a "recollection" that the "N" model was lengthened 2" to move the center of gravity…" "…You have no such "recollection" because you have NEVER read or heard it anywhere. You made it up to support the use of your erroneous data because you can't admit that you're wrong…"

Edited from JonJGoldberg Posted: Sun Nov 27, 2005 11:27 pm
( http://www.ww2aircraft.net/forum/about1116-0-asc-100.html )
"…I thought the 2" exchange closed: You asked me to post source info, I posted it. You rebutted, asking for justification. I explained continue not to be able support my statement with any documented reference, in perfect cadence of our exchange; not as you suggest, by 'sudden recollect'. I may be erroneous ( serving a vat of bull), as declared when I answered your question the 1st time. If it is found that the 2" difference is bull, or because of anything other than CG adjustment, I will, as always, admit error/s. I've not made the admission Sal; I'm still waiting on access to your 'service manual' source data, which is to include 'D' dimensions please."

You never provided your service manual evidence, even now as I write this Sal, I have found posted this info for all, with WW2aircraft member help.

OK now… What happened during your vacation from this site is I aquired, and exchanged a lot of data, with the members here. I have learned so much in the past 6 months about WW2 aircraft I'm shocked. The two inch question is still a mystery to me. I now have the manuals yet there still is a question… I post photos of 'errors within source documents' as evidence as to why below.

Theories I've considered other than CG, any one of which may force me to apologize to you; proof I'm out of my mind; none of which do I remember reading a tie to the two inches, nor were they covered in our exchange originally:
*Spinner Cap no Spinner Cap
*Hamilton Prop or Curtiss Prop Spinner Cap
*P-47N
*P-47N-1 1944 Additional internal and external fuel tanks, Curtiss paddle-blade prop. Was the aircraft lengthened here in this mod, can anyone help here?
*P-47N-5 1945 R-2800-73. Last combat model
*P-47N-15 1945 Ten Rocket Shackles
*P-47N-20 1945 ?

You should read further on…. Start here: JonJGoldberg Posted: Sun Nov 29, 2005 10:12 pm
( http://www.ww2aircraft.net/forum/about1116-0-asc-120.html ) to find out about your assertions about my 'combat weight numbers' ammo, radios.

As for the emoticon you should use Sal, I'd rather not,

Wmaxt, let me apologize again for my mis-quote of you, thank you for the '38 clarification. I should have figured that the leading edge tanks may not have been installed, as opposed to not filled. I also owe a qualified apology to the FTEB @ WF, because wmaxt if you are correct, I discredited them unjustly .

Sal your description of how web servers work I was not able to fully follow, but the attachments are frozen in time, as you state in the added in the brackets,

Huh? Where did I state that "the attachments are frozen in time"?

I said the opposite - "Therefore, when you posted your thread with a link to the .pdf, the .pdf as linked at that specific moment was not frozen in time in the system."

Think about it. Create a pdf. Label it JJG. Link it to this forum. Now make a change to the JJG pdf. Open the link and the changed pdf will be what opens. The master file as you put it, doesn't keep a copy of the pdf as it existed when it was merely liked on the forum. Now if you had posted the pdf chart itself instead of merely a link to a pdf chart, it would have been frozen in time. You understand this very well Jon.

As to your length data. I don't know what to say except that there appears to be some screwey data flying around.

Sal I left out the word not; the sentence should read:

Sal your description of how web servers work I was not able to fully follow, but the attachments are frozen in time, not as you state in the added in the brackets, and stats are visible for all to see, all of my old links (revisions, attached .PDF-s) still work, display different documents; they contain all of my original, as you claim, erroneous, that are now good cause I changed them numbers.

I apologize.

Last time, the links that you refer to, that I or other members use to 'attach' files to postings are links to files within WW2aircraft.net servers. They are not links to my nor your nor anyone else's computer. At the time you attach a file to your post, you are creating a 'one time' permission instruction to the WW2aircraft.net server to 'retrieve' the file you identified by supplying a file path or 'link' through the 'Browse' button on the 'posting' page.

The 'one time' permission instruction, or link, is stored by depressing the 'Add Attachment' button, so that another permission instruction, or link can be accepted; or discarded by pressing the 'Delete Attachment' button.

The 'Preview' button will execute your permission instructions by locating and displaying either the images from your computer, or by displaying a 'download target icon' in the from of a 'link' to your computer; allowing you to change and or update until you either exit, leaving the data un-posted on the WW2aircraft.net server; or you press the 'Submit' button.

Pressing the 'Submit' button will execute your permission instructions by locating, copying, then 'submitting' your targeted files from your computer onto the WW2aircraft.net server; 'archiving' them.

Once this is done, you are 'returned' to the forum; you are viewing a snapshot of that archive you provided the members of WW2aircraft.net from the WW2aircraft.net server. The post and attachments no longer have any association with the 'donor' computer.

Since they are now not on your computer, I may continue to view them even if your computer was 'taken-out' for what-ever reason; you may use the files to restore your computer.

So that events such as you now claim happened, can't happen without 'notification', Aviation forum postings attachments, unlike our personal WW2aircraft.net siggie image embedded message, when edited, or changed, are marked with an 'edit' stamp.

The 'links' in my (anyones) postings taking you to pages within Aviation threads, with the exceptions of personal WW2aircraft.net siggie images their embedded messages, on WW2aircraft.net server are covered by the rules explained above. Therefore you, anyone else interested may see what I posted, as I posted it, as verified by the time or edit stamp. The only changes that may take place un-announced are changes to a siggie image its embedded message; or to a member profile message; or by admin.

Last time, the links that you refer to, that I or other members use to 'attach' files to postings are links to files within WW2aircraft.net servers.

Really? So when you merely create a link to a web page, the web page itself is frozen in time in the "master file" as you say?

It is neither necessary nor practical for this to be the case Jon. It's called limited hard drive space! If I linked to an entire encyclopedia that would completely open under one link, the "master file" would NOT save the entire encyclopedia by virtue of linking to it.

Lets say there are 30,000 changes to the encyclopedia (under the same link) over the course of a year. Will the "master file" save 30,000 entire copies of the encyclopedia or just the copy that existed when initially linked? Why is that?

It will save none of them Jon. It is never necessary to pull a copy from the "master file" when it can be retrieved via the linked servers. Therefore it is not saved which conserves hard drive space.

Like I said earlier. If a web page was merely linked to this forum and thereafter ceases to exist, you can not bring it back from the dead by resort to the "master file"