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2017-11-20

 
 

Background Notes - General Purpose Bombs

 
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Aircraft Weapons

 AAC™ Bombs Aircraft Weapons Background Notes

 WWII & Cold War GP bombs

 Mk118.3000lb

 Demolition bombs

 Guided bombs

 Nuclear bombs - List of US bombs

 Explosive Content

Reference documents for this page :

See at bottom


     
 

US M118 3,000 lb BOMB REPRESENTATION

 
 

INTRODUCTION

Atlantic Air Combat™ essentially refers to "general purpose" gravity bombs, with a couple of other items co-existing with this main core of weapons.  Generally speaking, most of these bombs are illustrated in the public domain, have an easily recognized shape with some actually being iconic.  This starting point applies equally to US and Soviet bombs to only mention the two main streams.

Then there are odd shaped or odd sized items.  It they are to be represented in AAC™, their representation should preferably reflect reality.  Their size might be modified somewhat to make cheats easier or feasible, but real size and shape are the starting point.

Then, that's where the US 3,000 lb M118 bomb seems to create a difficulty.  First, it is rarely referred to in details as like its lighter cousin, it's less famous than a WWII vintage or a more recent Mk80 series.  Fortunately, there are official publications, but its representation on these pages doesn't seem to fit the data and the data is apparently conflicting between OP-1280 (1955) and TM-1325 (1966)

BACKGROUND INFORMATION

OP-1280

(1955)

Showing Meaning Should show

Weight

-

TM-1325

(1966)

-

-

Should show

Weight

-

Bomb 

130.00"

515 pixels

130.00"

515 pixels

FinM132

162 lb

Bomb 

185.00"

-

-

733 pixels

FinM132

-

Body

90.13"

264 pixels

66.64"

357 pixels

Tritonal

1888 lb

Body

90.13"

-

-

357 pixels

Tritonal

1975 lb

Body

24.13"

68 pixels

17.42"

96 pixels

Total

3020 lb

Body

24.13"

-

-

96 pixels

Total

3049 lb

Tail

14.10"

99 pixels

25.00"

133 pixels

-

-

Tail

33.60"

-

-

133 pixels

-

-

Tail

40.40"

254 pixels

64.12"

160 pixels

-

-

Tail

40.40"

-

-

160 pixels

-

-

Lugs

30.00"

89 pixels

22.46"

119 pixels

-

-

Lugs

30.00"

-

-

119 pixels

-

-

Issue with the 1955 representation

As shown in the table there are major discrepencies between the published data (essentially a total length of 130") and the associated representation.  Not to mean it's ALL WRONG but at least there is room for questioning.  When looking at the 1966 data, things are getting a lot clearer, and perhaps the 130 overall length was referring to an initial "short tailed" variant.

As shown on page 165 of the 0P-1280 (1955), the M118 is illustrated as shown below.  This image has been "cleaned" for the purpose of these notes but not resized.  So, whatever the scale (130" being represented by 515 pixels), it's shown as is, and it doesn't take a sharp eye to note that the rear and side views are not at the same scale.  They have been "aligned" here for convenience but no more.

- -

The drawing has been further cleaned up, and the rear view has been rescaled to match the profile height : 69 pixels

This representation is a problem.  If the 130 inches of length are represented by 515 pixels, then the 24.13 inches diameter should be represented by 515×24.13÷130=95.59 pixels.  With a profile height of 69 pixels, this "official" illustration is actually depicting a Ø of 17.42 inches....  Or vice versa, if a Ø of 24.13" is correctly represented with 69 pixels, then we are looking at a length of 515÷69×24.13=180.10" (4.575 metres) which by the way would put the lenght/diameter ratio at 7.464, close to the ratio of 8 generally advertised for this weapon.  As mentioned, the "rabbit" may lay in the fact that this visual actually depicts 185 inches rather than 130.

Incidentally, a secondary illustration grabbed from some other source shows the bomb body measuring 7.5 ft (thus 90").  That's consistent with data and when resized to match the above illustrated Ø, this part fits neatly (the blue area in the above outline).  But at the scale used, this is clearly not illustrating 90 inches of length for the body, further fueling the suspicion about the "130 inch" length.

Resizing the Visual

As we in AAC™ are more interrested into a "short" 3,000 bomb (to favour it being carried internally)  and because these two documents weren't found at the same time, it has been imagined that, relying on the published data but with a 33.6" tail span, the "Mk118" might be represented in AAC™ with the proportions shown below.

Length : overall

515 pixels 130.00" Fin span - 133 pixels 33.60"

Length : body

- 357 pixels 90.13" Fin length - 160 pixels 40.40"

Diameter

- 96 pixels 24.13" Suspension lugs - 119 pixels 30.00"

1st ADDENDUM REFERRING TO TM-1325 (1966)

Believing the matter was under wrap for a while and, contrary to my bad habits, wishing to properly assemble mysources, another document surfaced..  Without scrapping it, it lead to rewrite the above speculation as this 1966 training manual shows data somewhat closer to the visual representation used earlier : a total length of ... 185 inches.  So far for the hopes to keep that thing as short as possible...   Whatever we'll do in AAC™, here are two revised visuals based on a 185" length, first based on 185" being represented by 515 pixels

Length : overall

515 pixels 185.00" Fin span - 94 pixels 33.60"

Length : body

- 251 pixels 90.13" Fin length - 112 pixels 40.40"

Diameter

- 67 pixels 24.13" Suspension lugs - 84 pixels 30.00"

This second graphic is based on the 24.13 inches diameter being represented by 96 pixels as we ventured into this "scale".  Both are the same naturally, and seem to make sense when compared to Vietnam war era photograph.

Length : overall

- 733 pixels 185.00" Fin span - 133 pixels 33.60" Basic scale: 515 pixels  =130.00"

Length : body

- 357 pixels 90.13" Fin length - 160 pixels 40.40"

Diameter

96 pixels 24.13" Suspension lugs - 119 pixels 30.00"

2nd ADDENDUM REFERRING TO THE BLU-11/A/B LASER GUIDED BOMB

In 1965, the USAF began to evaluate laser guidance for free-fall bombs which eventually lead to the development of the Paveway series.  As such, these laser guided  bombs are beyond the scope of AAC™, but the M118E1 based GBU-11 had a much shorter tail and might approximatively be illustrated as below.  Data from designation-systems.net (left) and the outline is partly based on a couple of photographs (the markings are fantasy).  The 25" body diameter is however brought back to 24.13" for this exercise

BLU-11/B

-

-

Weight

-

-

-

#

-

-

-

Should show

Weight

-

Bomb 

165.00"

-

Tritonal

1975 lb

-

-

Bomb 

.00"

515 pixels

-

-

Tritonal

1975 lb

Body

90.13"

-

Total

3066 lb

-

-

Body

90.13"

357 pixels

-

-

Total

3000 lb

Body

25.00"

-

-

-

-

Body

24.13"

96 pixels

-

-

-

-

Tail

48.00"

-

-

-

-

-

Tail

.00"

515 pixels

-

-

-

-

Tail

"

-

-

-

-

-

Tail

.00"

515 pixels

-

-

-

-

Lugs

30.00"

-

-

-

-

-

Lugs

30.00"

89 pixels

-

-

-

-

FANTASY VARIATION

This short tailed GBU-11/B is the opportunity to review the idea of a "short" 3,000 lb bomb with a tail design inspired by early (or late ?..) M117 bombs.  With a cap less length (calculated) of 130½ we are back to square one.   All this for that....

Length : overall

- 524 pixels 132.00" Fin span - 126 pixels 32.00" Basic scale: 515 pixels  =130.00"

Length : (no cap)

- 517 pixels 130.50" Body Ø 96 pixels 24.13"

FALSE REPRESENTATION OF THE M118 IN ATLANTIC AIR COMBAT™

Shipbucket's FD Scale (22.093 pixels/metre)  is usually used to represent weapons (and aircraft for that matter).  Until now, the projected 3,000 lb "Mk118" bomb has been represented as shown on the left.  Then, this 13×51 visual doesn't match any data and the mistake is easy to spot : 90" length oa instead of 90 body length.

Naturally, we remain free to exercise our artistic freedom  and an AAC 3,000 lb bomb, standing for the US M118, may well continue to be represented as initially outlined as this shortened length favours it being carried internally inside bomb bays.  It's a cheat, but just one among many others.  If not, these notes provide the ground for an update which would also involve of all bomb bays already outlined.  In so doing, some aircraft may loose this weapon in their internally carried loadouts.  The translation of some of the above visuals in FD scale are as follows :

tilted 45°

tilted 45°

Length : oa

----- 90.00" or 2.286 m

Length : oa

----- 130.00" or 3.302m 72.95 pixels

Body Ø

----- 23.00" or 0.584 m

Diameter

----- 24.13" or 0.613m 13.54 pixels

Tail span

----- 24.25" or 0.616 m

Tail span

----- 33.60" or 0.853m 18.85 pixels

Length : oa

----- 185.00" or 4.699m 103.82 pixels
Reference Documents

OP.1280 (1955)

The key pages for bomb data are bordered

M117   750 lb

  
M118 3000 lb

Page 159 Page 160 Page 161 Page 162 Page 163 Page 164
 

TM.1325 (1966)

The key pages for bomb data are bordered

M117   750 lb

  
M118 3000 lb

Page 165 Page 166 Page 167 Page 168 Page 2-27 Page 2-28
 

No related to the M118 dimensional issue, but associated with the M117 is the MC-1 gas bomb, described in the same 1966 document

No more related to the M118 visual issue is a similarly shaped 250 lb training bomb, the M124 also in this 1966 document.

Page 2-62 Page 2-63 Page 2-86 Page 2-87
 
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