Paddle blade P-47 and P-38J

Discussion in 'Aviation' started by Jank, Mar 8, 2006.

  1. Jank

    Jank Member

    Joined:
    Mar 21, 2005
    Messages:
    679
    Likes Received:
    1
    Trophy Points:
    18
    Trying to compare the P-47 padle blade and the P-38J but don't know about the climb rates. The paddle blade P-47D that came out in 1944 had a climb rate of 3,120fpm at 5,000 feet.

    The P-38J coulod reach 20,000 feet in 7 minutes flat.

    Does anyone have any data for each aircraft at the same altitude?
     
  2. Twitch

    Twitch Member

    Joined:
    Feb 4, 2006
    Messages:
    809
    Likes Received:
    1
    Trophy Points:
    18
    Occupation:
    historical combat aviation writer
    Location:
    City of the Angels California
    P-47D-35-RA hit 20,000 feet in 8.5 minutes
     
  3. Sal Monella

    Sal Monella Member

    Joined:
    Apr 20, 2005
    Messages:
    223
    Likes Received:
    0
    Trophy Points:
    16
    Occupation:
    Administrative Assistant
    Location:
    Redwood City
    Twitch, can you share where that data came from? I have some interesting data that I will post.
     
  4. Sal Monella

    Sal Monella Member

    Joined:
    Apr 20, 2005
    Messages:
    223
    Likes Received:
    0
    Trophy Points:
    16
    Occupation:
    Administrative Assistant
    Location:
    Redwood City
    As you can see, time to climb at combat power to 20,000 feet is right at 7 minutes. The P-47D with the paddle prop blade was a very different animal indeed. Francis Gabreski said that after the paddle blade was installed, the Germans found that they could no longer just climb away from the Thunderbolt.

    [​IMG]
     
  5. Jank

    Jank Member

    Joined:
    Mar 21, 2005
    Messages:
    679
    Likes Received:
    1
    Trophy Points:
    18
    Wonderful chart Sal
     
  6. Magister

    Magister Member

    Joined:
    Dec 11, 2005
    Messages:
    183
    Likes Received:
    1
    Trophy Points:
    16
    Occupation:
    programmer
    Location:
    Cupertino, CA
    Yes, as you say, the paddle bladed Thunderbolt was a different airplane. She she got a 400fpm boost in climb which is clearly borne out by the chart you have provided.

    Very impressive climb for a 14,500lb airplane in 1944.

    Thanks for the info!
     
  7. Aggie08

    Aggie08 Active Member

    Joined:
    Apr 15, 2005
    Messages:
    1,012
    Likes Received:
    0
    Trophy Points:
    36
    Occupation:
    Student
    Location:
    Texas
    I've never heard of a paddle blade. Anyone have pictures?
     
  8. Sal Monella

    Sal Monella Member

    Joined:
    Apr 20, 2005
    Messages:
    223
    Likes Received:
    0
    Trophy Points:
    16
    Occupation:
    Administrative Assistant
    Location:
    Redwood City
    I believe it was fitted on all the D-22 and later series starting early in 1944. It had a broader chord and more bite. It really helped out with the P-47's rather anemic low altitude performance.

    I don't have side by side comparison pictures.
     
  9. Twitch

    Twitch Member

    Joined:
    Feb 4, 2006
    Messages:
    809
    Likes Received:
    1
    Trophy Points:
    18
    Occupation:
    historical combat aviation writer
    Location:
    City of the Angels California
    Sal- the climb figure is typically found in about any aircraft stat book. Initial climb rate is about 3,200FPM. Time to altitude is more meaningful since initial climb rate can and does fall off by differing amounts depending on the plane.

    The insight from Gabreski is dead similar to Bob Johnson's. While us little kiddies fart around with the magic of specification comparisons in the real world guys like Zemke, Gabreski, and Johnson capitalized on things like the new prop and the Jug's high roll and dive rate to dominate the battles they were in regardless of what any book says about performance.
     
  10. wmaxt

    wmaxt Active Member

    Joined:
    Dec 5, 2004
    Messages:
    1,208
    Likes Received:
    0
    Trophy Points:
    36
    Occupation:
    Engineer/Retired
    Location:
    Boise, Idaho
    The Paddle blade props also had a more sensitive control mechanism that was more effective, the same type of system added a lot to the P-38K too.

    The Paddle blade P-47D was also faster than the P-38J (421mph @ 25,800ft) but about the same as the L, I think.

    The P-38J/L could get to 20,000ft in 5-5.4min in WEP here is data from AAF Flight test 47-1706-A, Randomly picked P-38J # 42-67869

    Altitude - Cl Rate - Time
    0 -------- 4,000 --- 0
    5000 ---- 3960 ---- 1.25
    10000 -- 3860 ----- 2.54
    15000 -- 3550 ----- 3.89
    20000 -- 3190 ----- 5.37
    25000 -- 2665 ----- 7.o6
    30000 -- 1830 ----- 9.32
    35000 -- 985 ------ 12.99
    40000 -- 100 ------ 25.14

    Heres a graph for an in house test of an L model

    wmaxt
     

    Attached Files:

  11. Magister

    Magister Member

    Joined:
    Dec 11, 2005
    Messages:
    183
    Likes Received:
    1
    Trophy Points:
    16
    Occupation:
    programmer
    Location:
    Cupertino, CA
    Whoa!

    4.5 minutes to 20,000ft with a full load of ammo and internal fuel? That's an average of 4,444fpm over the entire climb. No way. Sorry. I don't buy it.
     
  12. Jabberwocky

    Jabberwocky Active Member

    Joined:
    Jul 24, 2005
    Messages:
    1,090
    Likes Received:
    16
    Trophy Points:
    38
    Occupation:
    Teacher
    Location:
    Japan
    Its more like 5 minutes to 20,000 feet for an L in full War Emergency Power.

    Tis really not that remarkable for a plane with 3,450 hp pulling it along.

    Standard Spitfire L.F. Mk IXs were tested to 20,000 feet in 4 3/4 minutes at +18 lbs. That droped to about 4 1/2 minutes at +25lbs. Some A&AEE testing had them pulling upwards of 5,700 feet/minute for the first 1,000 feet or so and better than 5000 feet/minute until 10,000 feet.
     
  13. Magister

    Magister Member

    Joined:
    Dec 11, 2005
    Messages:
    183
    Likes Received:
    1
    Trophy Points:
    16
    Occupation:
    programmer
    Location:
    Cupertino, CA
    Its more like 5 minutes to 20,000 feet for an L in full War Emergency Power.

    Not according to that chart!

    Tis really not that remarkable for a plane with 3,450 hp pulling it along.

    It is when you figure that it weighs in at 17,500 at combat load! (full ammo and internal fuel)

    Standard Spitfire L.F. Mk IXs were tested to 20,000 feet in 4 3/4 minutes at +18 lbs. That droped to about 4 1/2 minutes at +25lbs. Some A&AEE testing had them pulling upwards of 5,700 feet/minute for the first 1,000 feet or so and better than 5000 feet/minute until 10,000 feet.

    Yeah well a P-38 at combat weight weighs in at over twice that of the Spitfire!

    The P-38K model had a broad chord propeller. Not the J and L series.
     
  14. the lancaster kicks ass

    the lancaster kicks ass Active Member

    Joined:
    Dec 20, 2003
    Messages:
    19,980
    Likes Received:
    4
    Trophy Points:
    38
    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?
     
  15. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
    Staff Member Moderator

    Joined:
    Apr 9, 2005
    Messages:
    23,205
    Likes Received:
    787
    Trophy Points:
    113
    Gender:
    Male
    Occupation:
    Aircraft Maintenance Manager/ Flight Instructor
    Location:
    Colorado, USA
    YEP!!!!

    Folks - been reading this thread and observing interesting discussion, but I'm gonna throw my 2 cents in here...

    I know its probably been said before but these tests were done under the best circumstances, maybe with "line" aircraft but never the less under somewhat controlled conditions flown by very experienced pilots. For my money stick with the POH - its probably the best representation of performance gathered based on factory and government tests designed for combat operations.
    In my P-38 manual recommended climb performance is listed at 54"MP, 3000 rpm at a combat weight of 17, 400 you're going to get 7 minutes to 20,000 feet at best rate of climb (Vx) - period. Of course more boost and less weight may get you up there quicker but the charts are formulated for a reason with those numbers and be rest assured a WW2 combat pilot is going to go with those numbers posted, not data gathered from Wright Patterson or anywhere else that is not part of the "official document," that being the POH or in USAAF terms the -1.....
     
  16. Magister

    Magister Member

    Joined:
    Dec 11, 2005
    Messages:
    183
    Likes Received:
    1
    Trophy Points:
    16
    Occupation:
    programmer
    Location:
    Cupertino, CA
    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.
     
  17. Dogwalker

    Dogwalker Member

    Joined:
    Dec 22, 2005
    Messages:
    448
    Likes Received:
    1
    Trophy Points:
    18
    Location:
    Manziana Field, near Rome
    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".
     
  18. Magister

    Magister Member

    Joined:
    Dec 11, 2005
    Messages:
    183
    Likes Received:
    1
    Trophy Points:
    16
    Occupation:
    programmer
    Location:
    Cupertino, CA
    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.
     
  19. JonJGoldberg

    JonJGoldberg Member

    Joined:
    Oct 14, 2005
    Messages:
    210
    Likes Received:
    0
    Trophy Points:
    16
    Occupation:
    HOME AUTOMATION TECHNOLOGY
    Location:
    NEW YORK, NEW YORK
    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/viewtopic.php?t=3703&postdays=0&postorder=asc&start=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.
     

    Attached Files:

  20. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
    Staff Member Moderator

    Joined:
    Apr 9, 2005
    Messages:
    23,205
    Likes Received:
    787
    Trophy Points:
    113
    Gender:
    Male
    Occupation:
    Aircraft Maintenance Manager/ Flight Instructor
    Location:
    Colorado, USA
    :lol: 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!!!!!!
     
Loading...

Share This Page