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Couple days ago i opened a discussion in Japanese Aircraft Message concerning this plane since the data available didnt made sense to me. Some answers are in http://www.j-aircraft.org/smf/index.php?topic=4699.0

The references are not wrong. The normal load of a Ki-48 II was 400 kg - which is to say 8 x 50 kg bombs. But it was fitted to carry 8 x 100 kg bombs - similar to Western bombers.

The specification for the I included 400 kg (882 pound) bomb load. "Normal bomb-load consisted of either twenty-four 15 kg (33 lb) bombs or six 50 kg (110 lb) bombs." In RHS we simulate the 15 kg bombs by using an ICB cluster - defining this a = 3 x 33 pound (or 15 kg) bombs. We use the right number = 8 x 3 = 24. So our I model does not carry 882 pounds of bombs - but 800 - simulating 792.

What is the source for the 8x100kg bombs? I only found 1764lb ( i suppose unitary warhead)  for the suicide plane.

Both figures are from our Japanese aircraft standard: Fancillon: Japanese Aircraft of the Pacific War, p. 107.

This is very deliberate: see text on p. 106:

"Although the maximum bomb-load of the Army Type 99 Twin-Engined Light Bombe Model 2 was double that of the Model 1 it was still insufficient, and in this respect the Ki-48 II compared poorly with contemporary Allied aircraft."

Farther down he describes how the suicide aircraft were modified - using a rod protruding from the nose to act as a contact fuse detonator - for the 800 kg bomb load.

Well but it seems in no place it says 8x100kg.
 
I regard that information as poor quality leaving too much detail out.
 
My interpretation is that the bombing mission load was not more than 500kg.
 
Reasons for that. Size of 8x100kg bomb in the plane is to much for bomb bay, weight of offensive load compared to similar sized/performance aircraft, comparison with Ki-48-I and engine
 
As quoted in that forum: "20 or 24 15-kg bombs, six or eight 50-kg bombs, three or four 100-kg bombs, two 250-kg bombs, or one 500-kg bomb"
 
Source refered:"The Encyclopedia of Japanese Aircraft 1900 -1945, Volume 4, Kawasaki Contents"
 
I think the 800kg was a special charge for suicide missions that we dont know much about except the protuding detonator. And that value is a reason of confusion.
 
 
 

"Although the maximum bomb-load of the Army Type 99 Twin-Engined Light Bombe Model 2 was double that of the Model 1 it was still insufficient, and in this respect the Ki-48 II compared poorly with contemporary Allied aircraft." 
 

 
I dont think it compared poorly with similar sized Allied aircraft.

I don't follow your reasoning. 100 kg bombs were standard JAAF weapons - long carried by Ki-21. The I model carried 400 kg - in the form of 8 x 50 kg bombs. If the bomb load doubled, it almost certainly was in the form of hard points going to 100 kg. Virtually all the general sources we use (there are four listing aircraft of all nations) say the same thing as Francillon - who is our control for Japan. We are more or less forced to go with the information we have. We don't just disregard the standard sources - when they confirm each other.

If you read the text about JAAF bombers, you will find that 8 hard points is standard. The original light bomber was 50 kg bombs. The original heavy bomber standard was 100 kg bombs. Ki-48 II - coming later - simply went to the heavy bomber standard. I am sure of this - and don't think it is time justified to track down where we know that from. I am too easily diverted from completing goals by diversions of this sort. The standards we use - Weal - Gunston - Francillon - and two others - all agree. That is almost certainly correct.

I disagree. The "double" is the only information you have that supports . We dont know if the 800kg is the suicidal and Francillon included it, if  he was doubling the Normal Bomb Load which would make 600kg the double value.   The points below that i already refered leads me to believe it is the first.

"The size of 8x100kg bomb in the plane is to much for bomb bay, weight of offensive load compared to similar sized/performance aircraft, comparison with Ki-48-I  engine makes it impossible to double the weapon load, The Encyclopedia of Japanese Aircraft 1900 -1945, Volume 4, Kawasaki Contents.

I close this issue now since you prefer "Weal - Gunston - Francillon" even if they dont have much detail.

When the suicide load is not the same, Francillon uniformly reports it as such. It is his standard usage to give the bomb load used operationally and not the suicide load in his statistics. If you look at all his listings, where a suicide load is different - and it usually is different - he gives it as a separate case. This is one of the few (or the only) exception - and that is because the suicide load involved a wierd triggering of the regular bombs - which is described. In many other instances the suicide bomb load was not a bomb at all - but explosives. Triggering mechanisms differ. In this case, the mechanism required a complete modification of the aircraft - by Tachikawa - which is also described.

There is no point in having standards if we won't honor them. And there is no point in saying or believing a bomb bay could not hold the load it was designed to hold. It is barely possible that 800 kg were carried as 16 x 50 kg bombs - but that case would be far more likely to involve volume problems than 8 x 100 kg bombs. In fact, I am pretty sure you can see the bombs photographically in the Osprey Ki-48 book - or some similar book. I have seen the load - it really is what it really was.

If you can upload the photo and the text here i'll appreciate.  I have found another support for the 500kg bombload = Kawasaki Ki-66

How does a Ki-66 support a 500 kg load for a Ki-48?

It is clear to me reading Francillon he uses operational values - he cannot say a Ki-48 II "doubles the bombload" of 400 kg without meaning 800 kg.

However, Gunston - who also says the load is 800 kg - adds the note it "was rarely carried." And since the Ki-48 I had a max load of 400 but normally carried 300 kg - it might be better to define normal load as 300 kg for the I and 600 kg for the II.

I wonder if you know that the smaller bombs - when carried internally - were tail loaded? The Allies pretty generally carried the bombs horizontally mounted, but the Germans and Japanese liked the tail loading - as it permits more bombs in a small bay near the weight bearing members of the aircraft. It also permits larger bombs to be carried using two hard points - thus a 100 kg bomb can be carried by two 50 kg hard points (although in that case, the 100 kg would probably be horizontal while the 50 kg would be vertically carried). Similarly, if points existed rated at 125 kg, you could carry 250 kg bombs using two of them, or 2 x 100 kg bombs mounted vertically (as on a medium bomber which can carry 250 kg or 100 kg bombs).

I am not sure where I saw the open bay photograph - and I don't have a dedicated Ki-48 book - but I can send for one.

I have seen open bay photos of Ki-48 but they are blurry and i got nothing from them (those that i have saw are here:http://www.ijaafphotos.com/). I doubt it is possible to put vertical loaded bombs in such tiny plane like Ki-48. Like you see in image below the bomb bay goes to under the pilot/co-pilot and you have the structure of the wing.

The information i have about Japanese 50kg bombs is that they have 1,14m Lenght X 190mm Diameter and the 100kg with 1,34m L X 241mm D. The 8x100kg or 4x100kg or maybe 6 if the bomb bay have size for 3 of them side by side which i doubt and is not refered in any place.







Post edit: The reference to Ki-66 is that it was the Ki-48 successor.

In general, a JAAF bomber will mount bombs in singles or in pairs - but not in triples - I agree. [The exception is when they load tiny 25 kg or 10 kg bombs - which might go to four abreast]. It appears that the "big" bombers normally carry three 250 kg bombs, but can carry four - I assume line ahead. The same aircraft normally carry 6 but can carry eight 100 kg bombs - I assume in pairs - also line ahead. But these same aircraft also can carry 50 kg bombs - and that was in fact the JAAF standard bomb - or even smaller 25 kg bombs. [JNAF preferred 60 kg and 30 kg bombs. JNAF larger bombers normally carry only three 250 kg weapons - with no provision for a fourth - apparently because they fit in the same length as a torpedo. Early JNAF bombers had removable bomb bay doors - so the torpedo is carried without them - semi recessed - while the bombs are carried internally - with doors fitted.] Since the number of 50 kg bombs is always double the number of 100 kg bombs - and the number of 100 kg bombs is usually double the number of 250 kg bombs - there may be some sort of mounting adapter equipment permitting doubling of the bombs carried. It appears that only the smallest bombs are carried vertically - while larger ones - and in Japan a 100 kg bomb is large - are carried horizontally.

I think your bomb data is right. I have some bomb listings and it seems to correlate with them. Apparently some weapons are shared - e.g. torpedoes or 800 kg shells cum bombs - but most bombs were service specific and not even the same size.

which might go to four abreast

I think in  Ki.48 to have 8x50kg bombs they have to be 4 abreast you cannot put more than 2 in line there is not enough bomb bay lenght. 3x 50kg Bombs in line tip to tip 3x1,14m is 3,42m, 2 cm more than 3,4m bomb bay.
 
 

"big" bombers normally carry three 250 kg bombs, but can carry four - I assume line ahead." 

 
 I doubt that can be put 4x250kg  inline. That means probably a bomb bay of 7m or more and not giving much tolerance which would be impossible. I think a 2 side by side plus 2 side by side making 2x2 is more probable.
 
The bomb data came from ORDATA http://maic.jmu.edu/ordata/Mission.asp site which is a gold mine concerning weapons and explosives from all over the world. It's a reference for disposal teams. You can see there are some curious Japanese weapons like a land rocket that propels a 250kg aircraft bomb like a mortar.

Well - Navy bombers can carry 3 x 250 kg bombs. That seems almost certainly to require they be line ahead. And that also tells us something about how long a bomb bay needs to be to carry four: about 1.33 times as long as an 18 inch torpedo.

The Army didn't like the 250 kg bombs - particularly before the war - when experience was limited to fighting land targets in China - and Mongolia. They used 25, 50 and 100 kg bombs. Apparently the standard was 50 kg bombs on light bombers and 100 kg bombs on "heavy" bombers. Unlike the Navy, and the Germans, the JAAF preferred internal bomb bays - and except for the Ki-51 - which was a dive bomber - that was their normal case. There was no provision for external loads - as say in Germany. This was to help overcome the engine size problem: you get better performance if you fly clean than with the drag of external loads. Lacking powerful engines, Japanese aircraft tend to be designed with very tight margins, minimal "frills" and little room for stretch. But a big departure from Navy practice was this: Army planes had a max load bigger than normal load (something I didn't understand) - while Navy planes normal load was the same as max load. Army planes tended to operate with 75% of max load - which is far higher than US bombers - which usually could carry 1 to 4 times as many bombs as their normal load. One USAAF manual rates bomber ranges with "normal loads" of 5000 pounds - yet these planes had much higher capacities over shorter ranges.

I don't understand the basis for challenging the maximum bomb load of a Ki-48? Why not the max load of some other plane - on either side? Why this particular one? The orignal Ki-48 had too small a bomb load, and the II model underwent protracted development to achieve several difficult impovements:

1) Double the bomb load (it is in the spec in fact)

2) Dive bomb delivery capability

3) Add armor protection for crew members

4) Improve defensive armament.

The latter was never achieved. Various things were tried - even a 20 mm turret - none of them very successful. But the bomb load and dive bombing technologies - there were several aspects of that - were achieved - and the latter was used on several follow on projects. It is very likely this aircraft could carry large numbers of small bombs - as in 16 x 50 kg or possibly 32 x 25 kg bombs - and it appears it NEVER was adapted to carry "heavy bomber" bombs like the 250 kg bombs. The typical load of the I model was 300 kg - in the form of 6 x 50 kg weapons - and it could handle 8. This might have been 4 x 2 or 2 x 4 - theoretically speaking. The II model was scaled up in some way - and I suppose it is possible it also carried only 50 kg bombs - since it was still officially a "light bomber." In that case it might have carried 16 x 50s in a 4 x 4 configuration. But I think you will find that Japanese bombers with centerline bombays had the main stress points right on the centerline. They could be adapted easily to handle pairs - side by side. But quads seems to be pushing it to me.

In any case, why do we care? The specification to double the load makes sense - and it appears it was achieved. Does it matter how? If it matters I will see what Buschel has to say.

Does this interest anyone?

http://www.clubhyper.com/reference/japa ... bsdw_1.htm

Very nice site m10bob

Navy bombers can carry 3 x 250 kg bombs. That seems almost certainly to require they be line ahead.

 
Yes but doesnt make sense if they can get a maximum 4x250kg.
 
 

4 x 4 configuration.

  Well i am surprised. How could you put 4x4 bombs 50kg bombs  in a Ki-48? There is no space.

ORIGINAL: Dili

Navy bombers can carry 3 x 250 kg bombs. That seems almost certainly to require they be line ahead.

Yes but doesnt make sense if they can get a maximum 4x250kg.

If we don't talk about later bombers - e.g. the G8N - which apparently could carry 16 x 250 kg bombs - NAVY bombers could NOT carry four 250s. It was ARMY bombers that could. NAVY bombers - fitted for torpedoes - apparently lack the volume for more than three - and the "bomb bay" was the size of the torpedo. The later ARMY Ki-67 used a different mechanism to mount torpedoes - and this was initially added only to some aircraft - later retrofitted. But it was not a semi-recessed bomb bay design - so it is not in the true naval pattern. But the Navy bombers (e.g. G3 and G4 series) are not listed with 1000 kg loads - and when the Okha is fitted the poor plane is a dog because it is way too heavy.

ORIGINAL: Dili

4 x 4 configuration.

  Well i am surprised. How could you put 4x4 bombs 50kg bombs  in a Ki-48? There is no space.

This is backwards: they did - so they could. Why are you challenging the data? No source says a I model could not fit 400 kg - and the 50 kg was the standard bomb. It may well be it was 4 x 4 - vertically mounted. Or it might have been in pairs - horizontally stacked 2 x 2 stacks of 2. In that case, the hard points would be 100 kg strong - and you could mount 2 x 2 100 kg in the same pattern. We need detail drawings or photographs to know. We don't do this for other planes - so I ask again - why this one????

The original specification called for a 400 kg bomb load (882 lbs).

"Normal bomb-load consisted of either twenty-four 15 kg (33 lb) bombs or six 50 kg (110 lb) bombs."

We simulate this using 100 lb ICB clusters to represent 3 x 33 lb bombs - and we carry 8 - so 8 x 3 = 24 -
we have the right number of 15 kg bombs. There can be no doubt we have the I model right.