Load Adjusters

[Noha307]

I was recently in an email conversation with Michael Konshak of the International Slide Rule Museum and it got me interested in making yet *another* list. This time it's trying to track down all of the different versions of load adjusters that the USAAF and USAF used. Quite surprisingly, they essentially single-sourced all of their load adjuster needs to the Cox and Stevens Aircraft Corporation. Luckily, this makes it fairly easy to reconstruct the list as there was only one designation sequence in use. Each "plate", as the specific slides were referred to, was identified by a small number printed in a few places on the slide.[1] Note that at some point during World War II, the numbers began to be prefixed with the letter "E" for an unknown reason.

List (Plate - Aircraft)

• 382 - A-30 & A-30A[2]
• 384 - B-17E & B-17F Revised (TSWM)
• 406 - B-34; B-37; Ventura I & II (TSWM)
• 407 - AT-9, AT-9A (TSWM)
• 447 - B-26B, C[2]
• 456 - AT-10[3]
• 482 - UC-64A[4]
• 540 - AT-7; SNB-2[2]
• 577 - A-20G-20 (with turret)[5]
• 603 - B-24D, E, G, H & J; PB4Y-1[6]
• E583 - AT-7; SNB-2[7]
• E584 - AT-11; SNB-1[8]
• E585 - CG-4A; LRW-1[9][2]
• E590 - C-54A; R5D-1[10]
• E604 - B-24D, E, G, H & J; PB4Y-1[2][11]
• E624 - B-17G[12]
• E654 - B-25; PBJ-1J[6]
• E655 - A-20G, H, J & K[13]
• E719 - B-29, B-29A[14]
• E728 - A-26C[15]
• E765 - UC-45F, JRB-4[16]
• E800 - B-29, B-29A[17]
• E803 - B-29 & B-29A[2]
• E956 - C-119B & C; R4Q-1[18]
• E956B - C-119B, C, F & G; R4Q-1 & 2[6]
• E970 - B-50A, D; RB-50A, B[19]
• E999 - C-97A & C; YC-97A; KC-97A & E[20]
• E1007 - B-47B & E[2]
• E1021 - SNB-5P[21]
• E1027 - R6D-1; C-118A[22]
• E1035 - KC-97G[23]
• E1078 - C-130A[24]
• E1111-3 - KC-135A[25]
• E1199-6 - EP-3E[26]
• E1209-6 - KC-130R[27]

The military also produced a number of film strips and training films on the use of load adjusters:

Film Strips (Number - Subject)

• FS 1-812 - Pilot's Introduction to the C-46 Airplane: Part X, Use of Load Adjuster and Loading Chart[28.1]
• FS 1-989 - Loading the B-17F Using AAF Load Adjuster[28.2]
• FS 1-2113 - Handbook of Weight and Balance Data: Part II, Use of the Load Adjuster[28.3]
• FS 1-2177 - B-29 Airplane: Weight and Balance, Part III[28.4][28.5]

Technical Orders

• T.O. 01-1B-40 - Handbook of Weight and Balance Data[29]
• T.O. 01-1B-41 - Load Adjuster Plate Numbers for USAF[29]
• T.O. 01-1B-43 - Weight & Balance Aircraft Classifications[29]
• T.O. 01-1B-47 - Tail-Down Weighing Procedures for Aircraft[29]
• C.O. 01-1B-49 - Maximum Alternate Gross Weights for USAF Aircraft[29]
• T.O. 01-1B-51 - Weight and Balance Records for Jet Aircraft[29]

Training Films (Number - Title)

• TF 1-3348 - How to Fly the B-26 Airplane Series: Loading[30]

A few notes:

• An explanation of load adjusters can be found in the article The Load Adjuster: It Looks Like a Slide Rule, But Is It? by Mortimer Hans.
• A summary of the principles of load adjusters can be found in Chapter 16 of the 1952 edition and Section 4, Chapter 3 of the 1955 edition of Aircraft Engineering for Pilots, AFM 51-42.
• Further information about load adjusters can be found starting on page 43 of Field Weight and Balance Control, Air Forces Manual No. 8.
• Load adjusters were intended to be used with the Handbook of Weight and Balance Data, AN 01-1-40. A draft copy can be found in a post in the Army Air Forces and Other World War II Forms thread.
• The box load adjusters came in also apparently included a short booklet of approximately 20 pages specific to the model of airplane they were designed for that explained their use. However, as most of the examples for sale online have long since lost the box, they are hard to find. A few rare examples are visible in the background of listings for an AT-7/SNB-2. A B-24/PB4Y and a single digitized example of the latter is available for purchase.
• AirCorps Library has a two page technical order, T.O. 01-1-168, instructing that an additional placard be placed above where the load adjuster is mounted in the airplane. It is particularly useful in that it demonstrates that they were stored in the airplane when not in use.
• Since they were intended to remain with the airplane, many load adjusters accompanied them to storage. Not unlike the CAF's nose art collection, a large number were removed from these airplanes at Kingman Army Air Field and now make up a collection on the Depot 41 website.
• Cox & Stevens produced a single sided instructional load adjuster made out of wood.
• They also produced one gag load adjuster called the "V-69 Alkajuster" intended to help the user hold their alcohol.

EDIT (23-05-26): Added a section with a list of applicable technical orders and 6 entries.
EDIT (24-01-30): Added a note with a summary of the principles of load adjusters.
EDIT (24-10-23): Added a note with further information about load adjusters.

Last edited by Noha307 on Wed Oct 23, 2024 5:47 pm, edited 3 times in total.

[turretguy]

Hello, I'm looking for an A-30, B-23 and C-74 load adjuster if anyone has one they'd like to part with.

Aviation memorabilia dealer Robert Chad LeBeau started a list of load adjuster plate numbers and I've added to that list. Apologies for the funky alignment, and I've grouped them by aircraft role rather than by plate number:

Bombers. Name Plate #
B-17E/F Flying Fortress 327
B-17E & B-17F 708
B-17E & B-17F (revised) 384
B-17F (With Elevator down springs) 461
YB-40 Flying Fortress 471
B-17G Flying Fortress E624
B-23 Dragon (unknown)
B-24D, E, F, G, H, J • PB4Y-1 Liberator E604
B-24 D, F, G (41-23640 & up) E428
LB-30 Liberator - Export Version E670
B-25C/D Mitchell 443
B-25G/PBJ-1G Mitchell E568
B-25H/PBJ-1H Mitchell (gun nose) E658
B-25J/PBJ-1J Mitchell E654
B-26A/B Marauder 412
B-26B/C Marauder 447
B-26F/G Marauder E665
B-29, B-29A Superfortress E800
B-32 Dominator E778
B-34 Lexington 344
B-36D/F/H Peacemaker E1000
B-45A Tornado E930
B-47B & E Stratojet E1007
B-47E Stratojet E1062
B-50A Superfortress E929
B-52C/D Stratofortress E1092
B-52C/D/E/F Stratofortress E1175
B-52G Stratofortress E1152
B-52G&H Stratofortress E1201
B-52H Stratofortress 603090
B-57C Canberra E1071
B-57E Canberra E1091
B-58A Hustler E1129
RB-66 Destroyer E1097

Attack
A-20G (Series 1-15) Havoc 543
A-20G-20 (with turret) Havoc 577
A-25A • SB2C-1, -3 • SBF-1, -2 • SBW-1, -2 Helldiver 552
A-26B Invader E697
A-26C Invader E728
A-28A, A-29 Hudson 343B
A-30 Baltimore 382
A-31 (RA-31 Series) RV-72 Vengenance 468B
A-35A Vengenance 934
YP-80A • P-80 Series Shooting Star E864

Tankers
KB-29P E931
KC-97G E1035
KC-135A Stratotanker E1111
GV-1 Hercules E1118

Reconnaissance
PB4Y-2 Privateer
P4M-1Q Mercator E1080
RB-36D, E, F, H Peacemaker E1001
RB-47E Stratojet E1056
RB-50A, B Superfortress E970
RB-52 (B-52A) Stratofortress E1097
RB-66 Destroyer E1097
WV-2 Warning Star E1054
EC-135J Looking Glass C-62084
E-3A Sentry E1216
E-3B/C Sentry 603192
EP-3E Aries II 1199

Patrol – Seaplanes
PBY-5, -5A • PB2B-1 • OA-10, -10A Catalina E649
PBY-6, PB2B-2 Catalina E753
PB2Y-3R Coronado E721
PBM-3C, D, S Mariner E638
PBM-3R E497
PBM-5S2 E1010
PBM-5 Mariner E716
P5M-1 Marlin E1016
P5M-2 Marlin E1059
SA-16 Albatross E1122
VS-44 349
Sikorsky S-42 163

Patrol – Land planes
PV-1 Ventura E692
PV-2, -2C Harpoon E702
PV-2D Harpoon E820
PBJ-1H/B-25H Mitchell E658
PB4Y-1 Liberator E604
PB4Y-2 Privateer E699
P4M-1 Mercator E974
P2V-3W Neptune E973
P2V-4 Neptune E987
P2V-5 Neptune E990
P2V-6, -6B Neptune E1026
P2V-7 Neptune E1063
P2V-7 J/J Neptune E1127
OP-2E Neptune E1183
P-3A (P3V-1) Orion E1150
P-3A E1171
P-3B Orion E1181
P-3C Orion E1192
Lancaster 10MR Lancaster E1043
Lincoln Mk. II Lincoln No plate number

Helicopters
H-5F, H-5G Fairchild-Hiller E927
HUS-1, -1A • HSS-1, -1N Seabat E1113
HR2S-1 Mojave E1094
CH-3C Sea King/Jolly Green E1166
CH-53A Sea Stallion E1180
HH-53B/C Jolly Green E1188

Training
AT-7C/SNB-2C Navigator E636
AT-10 Navigator (wooden) 456B
res for AT-11 Kansan
AT-17 (UC-78) Bobcat 395B
AT-18, -18A Hudson 463B

Utility
R4Y-1 Samaritan E1086
T-29A/B/C Flying Classroom E1008
C-2A Greyhound E1179
US-3A Viking E1214
U-1A Otter E1101
JD-1 Invader

Cargo
UC-45F Expediter E710
C-46, C-46A • R5C-1 Commando E547
C-46E & F 816
C-47, R4D-1 & -5 E646
C-47A/B• R4D-1, -5, -6 Skytrain E734
R4D-8 1024
CG-4A • LRW-1 Haig (Hadrian) E585
CG-15A Glider
C-49A, B, C, D, J, K • C-50, B, C, D • C-53, A, B, C • R4D-3 Skytrain E588
C-53D Skytrooper E587
C-54B • R5D-2 Skymaster E672
C-54B, -54D • R5D-2, -3 E784
C-54G, R5D-5 Skymaster E828
C-60/C-60A (also C-56) Lodestar 440
C-64A Norseman E643
C-69 Constellation E817
C-74 Globemaster (unknown)
UC-78 (AT-17) Bamboo Bomber 395B
C-82A, N Packet E797
C-87 • RY-2 Liberator Express E688
RY-3 Liberator Express E780
C-97A/C, YC-97A, KC-97A, E Stratofreighter E999
C-109 Liberator (fuel carrier) E653
C-117A Super Skytrain E836
C-118A/R6D-1 Liftmaster E1027
C-119B/C • R4Q-1 Flying Boxcar E956
C-121C Constellation E1085
C-123B Provider E1065
C-124C Globemaster II E1030
C-130B Hercules E1114
C-131B Samaritan E1072
R7V-1 Constellation E1029

Boeing 377 (Pan Am) E985
Douglas C-54-DC (Pan Am) E948

There was a clear plastic weight and balance calculator for the B-18. I think the B-18 was too early for the Cox and Stevens load adjusters.
Hope this helps.
Nick

[turretguy]

And a couple more:

C-121A E957
C-124A E1023
C-130A E1078
C-131A E1033
C-135A 1146
HH-3F 1189
HO3S-1 (unknown)
JRB-3, -4, -6 • SNB-3, -4, -5 E971
KC-130R E1209
UC-64A 482
TF-1
C-47 Series 444
DC-3 Passenger 781

[p51]

I'm glad you included the B-32 one. I knew a guy in the 90s who found on of those at an antique shop, still in the cardboard box. I remember holding it in my hands, even back then when you could find the more common ones easily, knowing those would as rare as rocking horse poop.

[Noha307]

So, I finally got around to making a page listing them on my website.

Apologies for the funky alignment, and I've grouped them by aircraft role rather than by plate number:

No problem. I was able to sort them with some quick work in Excel. The bigger issue is that I was trying to list each entry exactly as it was written on the slide rule and it seems like some extra information, such as aircraft nicknames or potentially alternate designations, were added and punctuation, such as the use of forward slashes and bullet points, was changed. I did a little cleaning up and the below is the result:

LeBeau/turretguy List (Plate - Aircraft)

• 163 - Sikorsky S-42
• 327 - B-17E, F
• 343B - A-28A, A-29
• 344 - B-34
• 349 - VS-44
• 382 - A-30
• 384 - B-17E & B-17F (revised)
• 395B - AT-17 (UC-78)
• 395B - UC-78 (AT-17)
• 412 - B-26A, B
• 440 - C-60, C-60A
• 443 - B-25C, D
• 444 - C-47
• 447 - B-26B, C
• 456B - AT-10
• 461 - B-17F (With Elevator down springs)
• 463B - AT-18, -18A
• 468B - A-31 (RA-31 Series) V-72
• 471 - YB-40
• 482 - UC-64A
• 543 - A-20G (Series 1-15)
• 552 - A-25A; SB2C-1, -3; SBF-1, -2; SBW-1, -2
• 577 - A-20G-20 (with turret)
• 708 - B-17E & B-17F
• 781 - DC-3
• 816 - C-46E & F
• 934 - A-35A
• 1024 - R4D-8
• 1146 - C-135A
• 1189 - HH-3F
• 1199 - EP-3E
• 603090 - B-52H
• 603192 - E-3B, C
• C-62084 - EC-135J
• E428 - B-24 D, F, G (41-23640 & up)
• E497 - PBM-3R
• E547 - C-46, C-46A; R5C-1
• E568 - B-25G; PBJ-1G
• E585 - CG-4A, LRW-1
• E587 - C-53D
• E588 - C-49A, B, C, D, J, K; C-50, B, C, D; C-53, A, B, C; R4D-3
• E604 - B-24D, E, F, G, H, J; PB4Y-1
• E604 - PB4Y-1
• E624 - B-17G
• E636 - AT-7C; SNB-2C
• E638 - PBM-3C, D, S
• E643 - C-64A
• E646 - C-47, R4D-1 & -5
• E649 - PBY-5, -5A; PB2B-1; OA-10, -10A
• E653 - C-109
• E654 - B-25J; PBJ-1J
• E658 - B-25H; PBJ-1H
• E665 - B-26F, G
• E670 - LB-30
• E672 - C-54B; R5D-2
• E688 - C-87; RY-2
• E692 - PV-1
• E697 - A-26B
• E699 - PB4Y-2
• E702 - PV-2, -2C
• E710 - UC-45F
• E716 - PBM-5
• E721 - PB2Y-3R
• E728 - A-26C
• E734 - C-47A, B; R4D-1, -5, -6
• E753 - PBY-6, PB2B-2
• E778 - B-32
• E780 - RY-3
• E784 - C-54B, -54D; R5D-2, -3
• E797 - C-82A, N
• E800 - B-29, B-29A
• E817 - C-69
• E820 - PV-2D
• E828 - C-54G, R5D-5
• E836 - C-117A
• E864 - YP-80A, P-80 Series
• E927 - H-5F, H-5G
• E929 - B-50A
• E930 - B-45A
• E931 - KB-29P
• E948 - Douglas C-54-DC (Pan Am)
• E956 - C-119B, C; R4Q-1
• E957 - C-121A
• E970 - RB-50A, B
• E971 - JRB-3, -4, -6; SNB-3, -4, -5
• E973 - P2V-3W
• E974 - P4M-1
• E985 - Boeing 377 (Pan Am)
• E987 - P2V-4
• E990 - P2V-5
• E999 - C-97A, C, YC-97A, KC-97A, E
• E1000 - B-36D, F, H
• E1001 - RB-36D, E, F, H
• E1007 - B-47B & E
• E1008 - T-29A, B, C
• E1010 - PBM-5S2
• E1016 - P5M-1
• E1023 - C-124A
• E1026 - P2V-6, -6B
• E1027 - C-118A; R6D-1
• E1029 - R7V-1
• E1030 - C-124C
• E1033 - C-131A
• E1035 - KC-97G
• E1043 - Lancaster 10MR
• E1054 - WV-2
• E1056 - RB-47E
• E1059 - P5M-2
• E1062 - B-47E
• E1063 - P2V-7
• E1065 - C-123B
• E1071 - B-57C
• E1072 - C-131B
• E1078 - C-130A
• E1080 - P4M-1Q
• E1085 - C-121C
• E1086 - R4Y-1
• E1091 - B-57E
• E1092 - B-52C, D
• E1094 - HR2S-1
• E1097 - RB-66
• E1097 - RB-52
• E1097 - RB-66
• E1101 - U-1A
• E1111 - KC-135A
• E1113 - HUS-1, -1A; HSS-1, -1N
• E1114 - C-130B
• E1118 - GV-1
• E1122 - SA-16
• E1127 - P2V-7
• E1129 - B-58A
• E1150 - P-3A
• E1152 - B-52G
• E1166 - CH-3C
• E1171 - P-3A
• E1175 - B-52C, D, E, F
• E1179 - C-2A
• E1180 - CH-53A
• E1181 - P-3B
• E1183 - OP-2E
• E1188 - HH-53B, C
• E1192 - P-3C
• E1201 - B-52G & H
• E1209 - KC-130R
• E1214 - US-3A
• E1216 - E-3A
• No plate number - Lincoln Mk. II
• Unknown - B-23
• Unknown - C-74
• Unknown - HO3S-1

There was a clear plastic weight and balance calculator for the B-18. I think the B-18 was too early for the Cox and Stevens load adjusters.

Actually, the other day, I came across something that sounds similar to what you're talking about. Someone posted a picture of a "C.G. Computer-Model B-17F" that was "[i]n the back of [their] Grandpa's B[-]17F Familiarization Manual". I've never seen anything like it before.

Hope this helps.

Yes, it definitely does! Thank you so much!

[Noha307]

So, according to page 5 of the 1 August 1948 edition of Publications Requirement Table, T.O. 00-5-3, the technical order we need is Load Adjuster Plate Numbers for USAF Aircraft, T.O. 01-1B-41:

(Source: AirCorps Library)

Unfortunately, it is listed as "restricted", which I would imagine significantly reduces the possibility of running into a copy in the wild.

[Noha307]

While checking out the museum's new Albatross today, I came across something that, while not strictly speaking a load adjuster, is something that reminded me a lot of one: a fuel tank dipstick. The reason I found it so interesting is that I have never seen an honest-to-goodness, commercially produced, vintage example before. Pretty much everything I've encountered up to this point, whether crude or well constructed, has been some sort of replacement. With extensive and heavy handed use, I presume the originals just wore out quickly and were discarded. Anyway, the revelation was that there is probably a whole series of these "liquid measuring gauges" specifically designed for each aircraft. (Which seems to be confirmed by an auction listing for a DC-3 dipstick by the same company.) A brief Google search for "Martin Welch & Co" turned up an interesting court case involving a dispute over the invention of the device that shed useful light on how and when it (supposedly) originated.

Main Tanks

Float Tanks

Non-Modified Drop Tanks

Modified Drop Tanks

[Noha307]

Two quick notes:

• Another example of the aircraft-specific booklets is included in a sales listing alongside a B-25 Pilot Training Manual. This example is particularly interesting because it was published by North American Aviation and not the military.
• Just to show how the load adjuster has remained relevant even after all these years, an example is still pictured on page 45 of a 2019 Navy manual.

[Noha307]

Thanks to a donation, I recently learned that Consolidated made their own whiz wheel-style load adjuster called the "Bal-o-Dial".[1] So far, it appears that it was only made for the B-24D.

A fun fact: It comes in a case that, as can be seen as a rectangle of stitches in a picture, even has a small pocket in the front to hold the operating instructions. For those wanting to read said manual, a scanned copy is available on the Internet Archive.