Paddle blade P-47 and P-38J

[Magister]

Lanc said: what's your point? does the spit's climb rate suddenly become void because the P-38's heavier? if the P-38 was the same weight as the spit would she climb the same? if the Queen had balls would she be the King?

Huh? The point is that the P-38 doesn't have the 4.5 minute climb rate indicated by that chart and couldn't do anything close to 5 minutes either. And yes, if the queen had balls, he would be the king.

Flyboy, 7 minutes is what I have as well.

[Dogwalker]

However, even the chart show a time of 5.37 (or only slightly inferior) to 20000. Every orizontal space in the chart means two minutes. It's only that the "6" of the chart seems a "5".

[Magister]

Tou are right. My eyes aren't very good.

Now that I look at it more closely, it looks like about 5.1 rather than 5.37 (It's just over 5.0 on the P-38L-5 at WEP and of course, that number is also suspect if you think the number is actually 7 minutes.

Thanks for setting me straight.

[JonJGoldberg]

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…

Jabberwocky I have a lot of respect for you; however, in this issue I do not agree with you… Full War Emergency Power could be used for a max duration of 5 minutes & the initial sea level climb rate at ‘full combat weight’ (Sal, another point from back in the day, by coincidence...) is 4,000 ft. p/m (@ 60”Hg)… but that is not maintained… & requires pushing the aircraft to beyond it’s ‘safe operating limits’

Magister, wmaxt in the past has pointed out that the Allison was cleared for higher operating pressures in the ’38 L; as high as 66”Hg. It’s not that I don’t believe this wasn’t done in combat, in an act of desperation, or anticipation, but here is why I agree with you; I understand that a ‘38 may achieve these numbers once. When you are done achieving this at the very least your engines will be a write off, if not… At 60 Hg you had 5 min. running time, so you make it to twenty thousand feet. Now what? Unless you’re on ‘holiday’ or suicide watch, or a test/sim pilot, you must cut back power… & avoid ‘combat’, or testing procedures for a time; so you better have gotten far enough away.

FlyboyJ, not fair... My p-38 manual states 54”HG as well. …But on page 27 in one version, up to 60”Hg can be used for ‘war emergency’ climbs. Now pbfoot & yourself used the tact that the charts I posted (to display that a 2G turn in one aircraft, as opposed to another, although implemented at the same ‘bank angle’ due to the same ‘loading’ represented two different turn rates) in the P-51D vs. FW 190D thread ( http://www.ww2aircraft.net/forum/vie...sc&star t=140 ) was used for ‘formation, or instrument flying’ & pbfoot especially asked why I was using them as they had nothing to do with combat. Are you not doing this here FlyboyJ? The 54”HG is the max setting, or ‘combat’ setting, it is not WEP, which could be used for a 5 minutes climb, right?.

wmaxt 1st told me of the website linked below, and I believe he references data found there in his post. On his behalf I invite you all to visit it to see some great stuff on Spits, P-47s, P-38s & other aircraft.

http://www.spitfireperformance.com/p-38/p-38-67869.html

Excerpts…

Flight Test Engineering Branch
Memo Report No. Eng-47-1706-A
4 February 1944

FLIGHT TESTS
OF A P-38J AIRPLANE

Flight tests have been conducted at Wright Field on the P-38J Airplane, AAF, No. 42-67869, at the request of the Fighter Branch, Experimental Engineering Division. These tests were made on this airplane primarily to obtain comparative performance data with similar tests on a P-47D-10, a P-39Q-5 and a P-51B airplane. The performance should be that of a typical production model as it was selected at random from airplanes which had been delivered from the factory. From 2 December 1943 to 21 January 1944 approximately 30 hours were flown on this airplane by Capt. G. E. Lundquist, Capt F. C. Bretcher, and Capt J. W. Williams.

High speed and climb performance have been completed on this airplane at a take-off weight of 16,597 lb. This loading corresponds to the average P-38 combat weight with full oil, 300 gallons of fuel and specified armament and ammunition.

The principal results are as follows:
Max speed at critical altitude, 25,800'
(60.0" Hg. Man. Pr. & 3000 rpm) = 421.5 mph

Max speed at sea level
(60.0" Hg. Man. Pr. & 3000 rpm) = 345.0 mph

Rate of climb at sea level
(60.0" Hg. Man. Pr. & 3000 rpm) = 4000'/min.

Rate of climb at critical altitude, 23,400 ft.
(60.0" Hg. Man. Pr. & 3000 rpm) = 2900'/min.

Time to climb to critical altitude, 23,400 ft.
(60.0" Hg. Man. Pr. & 3000 rpm) = 6.49 min.

Service Ceiling = 40,000'


The airplane was equipped with wing racks, otherwise the configuration was normal with all flights at a gross weight at take-off of 16,597 pounds with the c.g at 24.75 m.a.c., gear down; and 28.5% m.a.c. , gear up. Gross weight included 300 gallons of fuel, 26 gallons of oil, 457 lbs. of ballast for ammunition, 100 pounds of ballast in the nose to locate the center of gravity within the allowable range, and automatic observer, complete radio equipment and antenna, and 200 pounds for the pilot. All items affecting the drag of the airplane may be seen in the photographs which are included at the end of the report.

Alt.Ft.----- Rate ofClimb Ft/Min. -----Time to Climb-Min.-----Intake Man. Pr.
0---------- 4000------------------------ 0-------------------------60"Hg----------
5000-------3960------------------------1.25---------------------60"Hg----------
10000------3820------------------------2.54---------------------60"Hg----------
15000------3550------------------------3.89---------------------60"Hg----------
20000------3190------------------------5.37---------------------60"Hg----------
*23400------2900-----------------------6.49---------------------60"Hg---------
*Critical altitude in climb for 26400 limiting turbo speed and 60.0" Hg. manifold pressure.


Conclusions
It is concluded that the performance reported is representative of the P-38J airplane, as the subject airplane was flown at combat weight and was also selected at random from P-38J airplanes delivered from the factory.
Recommendations
It is recommended that this method of selection of airplanes for flight test be adopted, and that hereafter all airplanes be test flown at the specified combat weight.

My own conclusions between these two, ’47 vs. ’38… Outstanding aircraft, the both of them... By WW2s end they were too expensive to purchase as the performance level offered did not better or maybe I should say, meaningfully better, the performance of an aircraft that cost less, the ’51. The USAAF was at war’s end able to purchase P-80s for less than a ’38, and about the same price of a ‘47... & I just skated the issue… I’d be flying the ’47. Although out classed by the ’38 in most performance categories, the ’47 does it for me for the following reasons… mostly ‘personal’ opinions, therefore hard to argue…

It’s better looking, especially in razor back form; I would take one PW 2800 over 2 Allison 1710s (although I do believe the Allison to be a fine ‘under praised’ power-plant); I would be an aircraft whose performance most closely matches my ‘style’ (in my sim) of combat flying, I do not dogfight much, I use tactic & speed, zoom & boom. The ’38 is also a Z & B fighter, but compressibility issues impede me, as I zoom in my ’38, I’m close to Vmax before entering into a dive, good thing they had installed dive breaks. The extra turn performance potential of the ’38, in most instances, is an invitation to disaster, they both should not be ‘dog fighting’, & exceed the human body’s ability to cope with G forces. The ’47 however will change direction more easily since it rolls better at turn fighting speeds (during WW2 centered at about 250 MPH). The overall performance of the ’47 is much more linear, it’s less tricky, picky, & finicky, it is less likely that I (you) might fly the plane apart. The firepower issue between the two would also be a classic debate. The ’38 is able to open fire at greater distances due to the nose mounted weapons… the 47 having more guns, wing mounted guns with firepower and bullet density at or near the point of convergence of those guns far in excess of the formidable firepower of the ’38. For me, & a bias that is formed from a 2D screen, as opposed to 3D reality, I’m more successful with the wing guns than with centered guns. I can much more easily establish in my mind the view of a successful firing solution as a point rather than a stream as the stream offers me ‘too many choices’, I tend to fire too soon, exposing my position. I do better close, exploiting the aid of a ‘convergence’ firing pattern in close since there is no radar lock (defeated in most of my CFS-2 installs) or homing missiles…
In my tables the ’38 out flies the ’47D by enough to outweigh the ‘47Ds firepower advantage. My tables ranked the ’38 as 3rd overall and the ‘47D as 5th overall out of 21. However, the 47N’s extra capacity of 500 rpg, as opposed to the D’s 425 rpg was enough to bring the N to 2nd overall position. In my tables I used WEP climb to represent the best climb rate, but did not include any ‘time to height’ figures, as I believe in ‘combat’ this is not a important issue, unless intercepting bombers or V1s. Here I briefly would defend my position by saying radar of the day was able to provide in most instances, enough warning, as should have your patrol aircraft, to meet your adversary at the ‘correct’ height. If sustained max climb was a way to press an edge while in combat, or provided a means of escape I believe more focus on this ‘maneuver’ would have been given. Unlike Twitch, I believe sustained climb is not a meaningful way to determine much. If a sustained climb was used in a turn fight as a means to press an advantage, or escape, it would be a gentile climb used in conjunction with a high (relative) rate of horizontal speed. After all, If your aircraft has a 1,000 FPM edge in climb rates, & I’m on your tail say just outside my ‘firing’ distance, and we both are traveling at about 200 to 250 mph, as you climb, you will slow down horizontally at a much higher rate than you gain height over me, after all you can only out climb me by about 35 mph, at best. Not only will I be in firing range if you choose this means of escape, rather quickly, but you would be giving me at least 15 seconds to kill you, unless you turn, or dive.

Yet again, the pilot, and or luck, as on race day, will be the determining factor, not the aircraft spec.

[FLYBOYJ]

Originally Posted by JonJGoldberg

FlyboyJ, not fair... My p-38 manual states 54”HG as well. …But on page 27 in one version, up to 60”Hg can be used for ‘war emergency’ climbs.

Nice to hear from you JJ - yep, forgot about that as well...

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.

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.....

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!!!!!!

[wmaxt]

Originally Posted by FLYBOYJ

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.

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.

Originally Posted by FLYBOYJ

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.....

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.

Originally Posted by FLYBOYJ

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!!!!!!

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

[Jabberwocky]

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.

[FLYBOYJ]

Originally Posted by wmaxt

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.

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.

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

AGREE!!!!

Originally Posted by Jabberwocky

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.

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 Monella]

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

[JonJGoldberg]

Sal I refer to >>
Edited from ( http://www.ww2aircraft.net/forum/abo...-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 ....

[JonJGoldberg]

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

[Sal Monella]

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/vie...asc&star t=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/warbird....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.”

[JonJGoldberg]

Hey Sal, Thanks.

Edited from ( http://www.ww2aircraft.net/forum/abo...-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/abo...-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/vie...sc&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/vie...sc&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.

[Sal Monella]

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.

[JonJGoldberg]

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