What the F is this.

[blockhaj]

So i found this picture of what is claimed to be a 500 kg bomb to be used on the Swedish version of the Junkers Ju 86 designated B 3.
(Original link: https://digitaltmuseum.se/021017362...-medeltunga-bombplanet-ju-86-med-beteckningen)
It is says m.b at the end which probably stands for minbomb "general purpose bomb". The only problem is that it doesnt look anything like the known 500 kg bombs used in the Swedish airforce during this era.
This is how the 500 kg bombs of the era looks like.

What it does look like is the 250 kg minbomb m/40.
Now i could easily just say its a mistake by the original owner of the photo but since i have time on my hands why not ask the internet? So my theory if it is a 500 kg bomb then it is a previosuly unknown 500 kg bomb used by the Swedish airforce in very limited numbers during a very limited time frame, like a prototype or test bomb. Or possibly a german bomb imported by the Swedish during the 30's. Have anyone seen any bomb in the 500 kg class that looked like this from the interwar/ww2 era?

 

[Dreamk]

It indeed looks more consistent with the 250kg minbomb but could also be consistent with the photo shown if you take into account the angle the photo was taken - we cannot see wether this bomb has one or two fuze pockets (the drawing BTW comes from the Ju86 booklet which does not indicates its source, if I remember well) - the only bombs of the interwar/ww2 period that I know with this characteristic reinforcing tubular circle of the fins are Swedish.

These are other pics of the 500kg minbomb :



and here are pics of the 250kg Minbomb (under the fuselage)
and

Would you happen to know what are the designation and characteristics of this one (I suppose a kind of depth bomb)?


and what is this??? mounted under Swedish Capronis

 

[blockhaj]

The 250 kg bomb under the B 17A (first pic) is not a minbomb but an övningsbomb (practise bomb).
The 250 kg bomb under the B 5C (the one with the bombfork) i suspect being the 500 kg pansarbomb as it differs from the 250 kg minbomb and övningsbomb m/40 but at the same time its notably smaller than the 500 kg minbomb m/41.

The small bomb i have no clue, ive seen it before but i cant remember where. It looks like a practice bomb due to the wear on it but it differs from the 8 kg övningsbomb m/40. When i looks closer it looks like 50 kg övningsbomb m/40 but with some welded stuff to the front. U can see 50 kg övningsbomb m/40 under the B 17A (250 kg pic 1). Compare the rudders on them and u will see what i mean. 8 kg övningsbomb looks more like 6 kg brandbomb m/39.

The Swedish capronis (b 16a, t 16a, s 16a, s 16b) could with an external mount called bombställ m/40 EM mount 1x 500 kg or 250 kg bomb. The bomb on the picture looks damaged and worn. Its possible its a defuzed 500 kg minbomb m/41 which is used for training purposes. Here is bombställ m/40 EM. https://digitaltmuseum.org/021025449363/plansch/media?slide=0

 

[Dreamk]

A AP Pansarbomb would be indeed logical for a dive bomber.

I got some more photos than seem to be related to the pic of Post #1 and if these are indeed the same bomb they confirm that it is indeed a 250kg Minbomb (a single fuze pocket can be seen on the 2nd pic)


What I suspect as being a depth bomb or an anti-submarine bomb seems indeed to be based upo0n a 50kg minbomb, with and anti-bouncing nose cap
Tthe 50kg minbomb is, among the Swedish bombs, the one on which data is the most available, probably because it was the most frequently used (most Swedish and Finnish plane could carry it underwings):

and by looking at the size of this bomb by comparaison to the hand of the person besides, I suspect that this bomb on show at the Flyvapenmuseum is a 50kg (and not a 500kg as written there) minbomb, but it may be the M/50 version and not the M/37 - they looked rather similar



BTW would you have more info/pics of this unidentified Swedish incendiary bomb from the 40s, seen here being filled:


and on the air dropped parachute mine F9:

 

[blockhaj]

Ive seen those other pictures too so its basically what i thought at the start, a mistake by the original owner.

The "depth bomb" is no minbomb as u can clearly see that the back of it is detachable unlike the minbomb which has a solid back.


The people at flygvapenmuseum does make a lot of mistakes. Most of them are just there for the job and not becuse they are historians and plane nerds. Its possible that the bomb there was just manufactured for the exibition. Although ive never heard of a 50 kg minbomb m/50? Looking at the blueprint and thinking rationally its most likely just an updated m/37 with modern explosives and minor tweaks. The m/37's where getting old at this point.

As for the incendiary bomb it looks like a 250 kg minbomb m/40. I wonder if they just fill it with explosives? The m/40 used an explosive called nitrolit which it basically a fluidly/oily substance. But its also possible its a prototyp bomb or a to me previously unknown bomb.
The only incendiary bomb i know of with a similar size from the era is 200 kg brandbomb m/51.


The last one is a mistake. Thats a mina m/F:7. Its a 300 kg magnet mine which was in service only used one the b 3d on a larger scale.
Mina m/:9 was torpedo shaped and looked like this.

 

[Dreamk]

Thanks for the mine identification - this enabled me to some order the data I got in my files:
here some pics of the M/F:7 Lydia
Height 1340 mm Diameter 700 mm Weight 370 kg
It was as a matter of fact an oscillating contact mine with acoustic sensor: Once dropped it sank to the bottom of the sea, the "flaps" on the sides folding out to slow the sinking speed, and laid there in waiting. When detecting the noise of a ship, it rose to the surface, hopefully hitting the ship bottom. If no hit occurred, the mine sank once again to return in "waiting" position

 

[blockhaj]

@Dreamk where do u find most of these pictures btw? The 50 kg minbomb m/50 is new to me for example?

 

[Dreamk]

Past issues of various Flyvapnet magazines (for instance look at this link https://www.aef.se/Flygvapnet/Notiser/Flottiljer/F1/F1_femtio.htm), archives (see for instance here http://arkis2dok.ra.se/kra/0602/b/003/1/sb.pdf) and terminal ballistics papers.
I have not yet been able to access the original historical documents of these bombs, although they are now available at the Krigarkivet and Flyvapen museum and one can get the references through the search engine of the various Swedish Digital archives and libraries project (see for instance https://sok.riksarkivet.se/?Sokord=...Ort=&DatumFran=&DatumTill=&AvanceradSok=False or see here: http://libris.kb.se/hitlist?d=libris&q=minbomb&f=simp&spell=true&hist=true&p=1) - it's a question of patience as each search engine looks only for some data bases.

BTW It appears that I have been misled on this drawing and misled you in accordance, I read once again the text from where this drawing was extracted and it appears that it is in fact a drawing of 250kg Minbomb M/50, diameter 370mm length 1497mm (bomb body, fins excluded) real weight 270kg including 140 kg of hexotol (HBX-3).

 

[blockhaj]

I have all of those pdfs too but for ex the "unknown" incendiary bomb is totally new to me. I have access to krigsarkivet but i have not been able to find the descriptions of the 250 kg and above bombs from the ww2 era.

Also where did u find the info about the 250 kg minbomb m/50?

 

[Dreamk]

I have access to krigsarkivet but i have not been able to find the descriptions of the 250 kg and above bombs from the ww2 era.

The documentation is simply not there - you must remember that till ww2, the Swedish defense establishment did not design or produce bombs - These were bought as "on the shelves" from Bofors AB - the development of aerial bombs by Bofors initiated in 1928, and the first models produced were the so called M/32 series, that were sold by Bofors to a large number of countries, ranging from Argentina to China - Bofors even tried in 1936 to sell them to the Germans after they decided to repudiate the Versailles treaty but Germany was interested in developing its own bomb production facilities.
Information on Bofors designed bomb is therefore to be found in Bofors Archives - it includes catalogues, and instructional notices (extracts of one such notice, in Spanish, for South American users, can be found in this forum - see the thread on Bofors bombs). It would really be worth to check what is available there, at Bofors.

info about the 250 kg minbomb m/50

I'll upload the paper and send you the link - it deals with a trial to validate a mathematical model of splinter fragments dispersion and other terminal ballistics matters - and uses a 250kg M/50 as test bomb

 

[blockhaj]

The documentation is simply not there - you must remember that till ww2, the Swedish defense establishment did not design or produce bombs - These were bought as "on the shelves" from Bofors AB - the development of aerial bombs by Bofors initiated in 1928, and the first models produced were the so called M/32 series, that were sold by Bofors to a large number of countries, ranging from Argentina to China - Bofors even tried in 1936 to sell them to the Germans after they decided to repudiate the Versailles treaty but Germany was interested in developing its own bomb production facilities.
Information on Bofors designed bomb is therefore to be found in Bofors Archives - it includes catalogues, and instructional notices (extracts of one such notice, in Spanish, for South American users, can be found in this forum - see the thread on Bofors bombs). It would really be worth to check what is available there, at Bofors.


I'll upload the paper and send you the link - it deals with a trial to validate a mathematical model of splinter fragments dispersion and other terminal ballistics matters - and uses a 250kg M/50 as test bomb

The 250 kg and 500 kg bombs were actually not built by Bofors byt by Aktiebolaget Svenska Järnvägsverkstäderna i Linköping (AJS) which was a sub part of Saab. Its possible that lower weight bombs where made by them too but i havent found anything on it. But besides that Saabs archive is connected with Krigsarkivet and so is Bofors old archive. And besides that too Flygvapnet made their own documentation of everything they used. Most of it is pocket books for service. Ive been able to find suchs books for all small bombs but not for the 250 kg and 500 kg bombs.
Here is an example.
(When i was gonna post an example i actually found the description of the 250 kg and 500 kg bombs "after 3 years.....")
Well im off to the archive tomorrow to photograph these books.

 

[Dreamk]

Great!
These are the kind of Bofors publications I was referring to:
This is from the 1931 publication

and this is form the 1936 catalogue

and these are plans drawings from the Sweden Military Museum - still with the mention Bofors on these plans


while the 12kg sprangbombe still relates to the M/32 series, the 50kg minbomb is the 50 kg minbomb m/37

At some point of time the Saab indeed "took over" from Bofors
My assessment is that this took place during the first Soviet-Finnish confrontation due to the more than intimate relationships existing in Bofors and Tolvan bomb production and design, and this could lead to diplomatic complications and marketing problems for Bofors, together with Bofors strategical choice of concentrating on its guns and ammunition lines.

This will be very interesting to see what you are going to discover in the archive - there is so little data presently available on these bombs and their fuzes.

 

[reccetrooper]

Looking at the photo, the trailer has a 4.50-18 tyre. The wheel rim is therefore 18 inches or 457mm.

Measuring the rim diameter for both wheels on the photo (which are different because of perspective), adding them together and dividing by 2, gives a dimension on the photo equal to 457mm on the centre-line of the full size trailer.

Dividing 457mm by the photo’s calculated centre-line dimension gives the scale of the photo.

If you measure the diameter of the bomb in the photo (which is on the centre-line), and multiply by the calculated scale, you have an approximate diameter for the full size bomb.

On my iPad screen I estimate the bomb to be approximately 421mm in diameter. A more accurate estimate could be made if you print the photo and accurately measure the print.

Is 421mm close to the diameter of any of the bombs you have discussed?

 

[blockhaj]

Great!
These are the kind of Bofors publications I was referring to:
This is from the 1931 publication
View attachment 144500 View attachment 144501 View attachment 144502 View attachment 144503 View attachment 144504View attachment 144505
and this is form the 1936 catalogue
View attachment 144506
and these are plans drawings from the Sweden Military Museum - still with the mention Bofors on these plans
View attachment 144507 View attachment 144508

while the 12kg sprangbombe still relates to the M/32 series, the 50kg minbomb is the 50 kg minbomb m/37

At some point of time the Saab indeed "took over" from Bofors
My assessment is that this took place during the first Soviet-Finnish confrontation due to the more than intimate relationships existing in Bofors and Tolvan bomb production and design, and this could lead to diplomatic complications and marketing problems for Bofors, together with Bofors strategical choice of concentrating on its guns and ammunition lines.

This will be very interesting to see what you are going to discover in the archive - there is so little data presently available on these bombs and their fuzes.

I know that bofors made bombs too. Some models were probably made by other weapons manufacturers too such as huskvarna och gustavs givärsfaktori and similars.
Although the archive was closed today so i will go tomorrow again.

 

[blockhaj]

Looking at the photo, the trailer has a 4.50-18 tyre. The wheel rim is therefore 18 inches or 457mm.

Measuring the rim diameter for both wheels on the photo (which are different because of perspective), adding them together and dividing by 2, gives a dimension on the photo equal to 457mm on the centre-line of the full size trailer.

Dividing 457mm by the photo’s calculated centre-line dimension gives the scale of the photo.

If you measure the diameter of the bomb in the photo (which is on the centre-line), and multiply by the calculated scale, you have an approximate diameter for the full size bomb.

On my iPad screen I estimate the bomb to be approximately 421mm in diameter. A more accurate estimate could be made if you print the photo and accurately measure the print.

Is 421mm close to the diameter of any of the bombs you have discussed?

It should be closer to 370 mm if its a 250 kg bomb. If u are correct in ur estimates then its not a 250 kg bomb which means i have more digging to do.

 

[Dreamk]

This is an interesting approach. I happen to have only partial data on the dimensions of these bombs: what I have for diameter is as follows:
Finnish 250 M/30 406mm (simialr to the Swedish M/32 series)Finnish 250 M37 340mm (Tolfvan, different from the Swedish 250kg M/37 and M/40 but most prossibly fitting the same bomb racks)
Finnish 450 M37 406mm
Swedish 250 M50 370mm

This would indicate that, with a diameter of 421mm this would indeed be a 500kg size bomb.

 

[Dreamk]

Some more pics of the elusive 40's Brandbombe:


The comparison with the 200kg M/50 brandbombe shows clear differences - fin shapes and dimensions, tail "pipe", ogival nose cone.


There are is also differences with the German Flammbomb 250/ Chemical KC250 (remnants sometimes found in Scandinavia as a huge number were dumped in the Baltic at the end of ww2) - the proportions are different, the fins are different, the body and ogive are different (not in a single cast steel body but rather rolled/ pressed steel sheets)

 

[blockhaj]

View attachment 144533

This picture says Stiklestad Nasjonale Kultursenter AS at the bottom. Stiklestad Nasjonale Kultursenter is located in norway. So maybe its a norwegian bomb?

 

[blockhaj]

So the fire bomb above is a british bomb dropped in norway.

 

[Dreamk]

It is definitively not a British bomb, nor an US/Soviet or German one.
It's really a very strange thing.
The "filling photo" comes from the Swedish Flygvapenmuseum archive (IDENTIFIER FVMF.003223) - unknown photographer
Its title is: Påfyllning av bränsle till flygbomb från fat till kapsel, 1940-tal. En man i arbete. (Refill of of an aerial bomb from a fuel drum, 1940s. Man at work.)