Jap "Heavy" bombers

[Miller]

Why were their bomb loads so light in comparison to Allied bombers?

For example, the main Jap bombers in the war, the Helen/Sally, carried 4 x 250kg bombs. Yet the equivalent B25/B26 usually carried double that (8 x 500lb) despite having pretty much the same power/weight ratio as the Jap a/c.....

[spence]

I think it may be because the Japanese a/c engines were less powerful as a general rule. IIRC the US/Allies were capable of producing higher quality metal for use in their engines.

[witpqs]

ORIGINAL: Miller

Why were their bomb loads so light in comparison to Allied bombers?

For example, the main Jap bombers in the war, the Helen/Sally, carried 4 x 250kg bombs. Yet the equivalent B25/B26 usually carried double that (8 x 500lb) despite having pretty much the same power/weight ratio as the Jap a/c.....

I think that (at least in game terms) the Allied planes you cite carried 6 x 500lb, or 50% more. I've only noted the Wellingtons carrying 8 x 500lb.

As to why, I have to let others answers for real, but I can speculate a little...

With the emphasis on range, that might have dictated a lighter load directly, and indirectly dictated a lighter load due to lighter structural design. Again, that's just speculation.

[Erkki]

ORIGINAL: witpqs

ORIGINAL: Miller

Why were their bomb loads so light in comparison to Allied bombers?

For example, the main Jap bombers in the war, the Helen/Sally, carried 4 x 250kg bombs. Yet the equivalent B25/B26 usually carried double that (8 x 500lb) despite having pretty much the same power/weight ratio as the Jap a/c.....

I think that (at least in game terms) the Allied planes you cite carried 6 x 500lb, or 50% more. I've only noted the Wellingtons carrying 8 x 500lb.

As to why, I have to let others answers for real, but I can speculate a little...

With the emphasis on range, that might have dictated a lighter load directly, and indirectly dictated a lighter load due to lighter structural design. Again, that's just speculation.

Allied bombers simply had more bomb bay space(mostly) and they get their full "Wikipedia-payload" for normal range. However they mostly flew with less than the full bomb load to increase range(to actually get to that "normal" range in game) and speed. In this regard the available bomb loads for bombers in game are not very consistent and arguably at least somewhat favour the Allies. I think the worst one off is the Ki-67 that only gets to carry 50% of the listed maximum real life bomb load. Similarly to Allied ones, many Japanese bombers including G4M could carry more bombs, equal to US and British, but would then suffer in range, again similar to Allied planes.

However at least the Ki-49-I in reality did not carry more than 3 x 250kg to its "normal" range while in game it gets the full load of 4 bombs. Possibly the same thing with the entire Ki-21 series, so at least in early war it goes both ways. Martin 139 could also do with a larger bomb load.

edit: what I wanted to say is that Allied planes mostly get their full bomb load with normal range, but Japanese planes mostly get the bomb load they had to carry to get the normal range in the first place, or the typical combat load instead of theoretical or practical maximum load they could take off with. There are exceptions for both sides.

[btd64]

Airframe construction, Range to target. I think that has a lot to do with it..

In fact, and I don't know if the game works this way,( Haven't tested it yet) If a B-25 attacks a target 2 hexes away, It should carry the FULL bomb load. If the same aircraft attacks a target near the end of its range, it may only carry a fraction of its normal capacity to be able to reach the target.....GP

[witpqs]

ORIGINAL: General Patton

Airframe construction, Range to target. I think that has a lot to do with it..

In fact, and I don't know if the game works this way,( Haven't tested it yet) If a B-25 attacks a target 2 hexes away, It should carry the FULL bomb load. If the same aircraft attacks a target near the end of its range, it may only carry a fraction of its normal capacity to be able to reach the target.....GP

Game does not work that way. There is no pro-rating of bomb loads in AE. (Yes, I know, it would be nice.)

[btd64]

ORIGINAL: witpqs

ORIGINAL: General Patton

Airframe construction, Range to target. I think that has a lot to do with it..

In fact, and I don't know if the game works this way,( Haven't tested it yet) If a B-25 attacks a target 2 hexes away, It should carry the FULL bomb load. If the same aircraft attacks a target near the end of its range, it may only carry a fraction of its normal capacity to be able to reach the target.....GP

Game does not work that way. There is no pro-rating of bomb loads in AE. (Yes, I know, it would be nice.)

Oh well. Would bring the game one small step closer to reality. GP

[Rising-Sun]

Japanese wanted to push range limit instead, lack of armor, etcs. So that why they have light payloads.

[wdolson]

Additionally the Allies also used 100 and 140 octane fuel and Japan was mostly limited to 87 and 92 octane fuel.

Different articles on Wikipedia are written by different people who use different criteria for their details, so while I will say Wikipedia is generally better than some people here give it credit, I also take it with a grain of salt.

The bombs loads were calculated based on data from the same sources for all nations as much as possible. When the air data team had to deviate from those sources, they were very careful to make sure the aircraft data conformed to the same standard. A few small errors crept in, but I don't know of any wholesale errors.

Bill

[Erkki]

Higher octane rating does not mean higher power(for a given engine). Palembang also had one of the largest high-octane gasoline refineries in the world, and there were pretty surely more in Japan(that were later bombed).

I think Wikipedia is a pretty good source for checking most stuff but there often seem to be mistakes, contradictions or missing important stuff when it comes to details.

[Symon]

Brother Bill is good with that octane crap. The usual pre-teens whine about hi-octane. The flight tests (TAIC, March, 1945) make it clear they were done with 92 octane, or 87 octane with methane. The usual pre-teen nonsense is just that.

Think some of the IJ bombers should get a push in range. The loadouts are right frikkin perfect, so go frikkin fish. I don't use your wikipoedia. I use the flight test reports from Wright Pat.

[rustysi]

ORIGINAL: Symon

Brother Bill is good with that octane crap. The usual pre-teens whine about hi-octane. The flight tests (TAIC, March, 1945) make it clear they were done with 92 octane, or 87 octane with methane. The usual pre-teen nonsense is just that.

Think some of the IJ bombers should get a push in range. The loadouts are right frikkin perfect, so go frikkin fish. I don't use your wikipoedia. I use the flight test reports from Wright Pat.

Are we saying that fuel quality had no impact on engine performance?

[Erkki]

rustysi: octane rating isn't fuel quality. An engine can be powerful and reliable even if it does not make use of high octane fuel's qualities.


Symon, can we have a post without curses? Also saying that "Oh I used this and that, and made calculations, complicated stuff, I wont be telling you, but the data is fine"(I'm referring to other threads mostly) does not help people understand why the data is now OK or at least better than it used to be, or evaluate it or the thought process behind it.

And I never even stated what my sources are.

[geofflambert]

Japanese metallurgy was not as good as US. Neither was Soviet for that matter. When they got their hands on a B-29 that landed in their territory in distress, they reverse engineered it and built some of their own. They were inferior to the real thing for that reason, but were still estimable. The US has pretty well pissed away much of that metallurgical knowledge and we have to go to Europe to get the good stuff (Italy, German and Czech).

[rustysi]

rustysi: octane rating isn't fuel quality. An engine can be powerful and reliable even if it does not make use of high octane fuel's qualities.

So, why the big push to develop high octane fuels. IIRC Jimmy Doolilttle did work on this prior to the war. High octane fuels are required for high performance piston engines, no?

[Erkki]

ORIGINAL: rustysi

rustysi: octane rating isn't fuel quality. An engine can be powerful and reliable even if it does not make use of high octane fuel's qualities.

So, why the big push to develop high octane fuels. IIRC Jimmy Doolilttle did work on this prior to the war. High octane fuels are required for high performance piston engines, no?

Because higher octane level allows for higher compression and temperature(and power) without premature detonation. So lighter engines to achieve the same power as an engine designed to use a lower octane fuel. But an engine designed for low octane gets little to no extra power from higher octane fuel.

Also difference between say 87 and 100 is not great - the scale is not linear so 87 octane does not have max compressibility 87% of 100 octane fuel.

[Gaspote]

ORIGINAL: rustysi

rustysi: octane rating isn't fuel quality. An engine can be powerful and reliable even if it does not make use of high octane fuel's qualities.

So, why the big push to develop high octane fuels. IIRC Jimmy Doolilttle did work on this prior to the war. High octane fuels are required for high performance piston engines, no?

High engine fuel give better performance with any motor. If you get more fuel than good craftmen, it's logical to upgrade fuel and not engine complexity.

[sandlance]

Patton just about has it right on. The air unit got the mission, The bomber or fighter was loaded with the fuel to reach the target, then loaded with ammo, what was left of maximum weight was bombs. Hence short range more bombs, long range less bombs.


Stephen Nelson FTG1(ss)ret

[wdolson]

The octane rating is the rating on how fast the fuel burns. The higher the rating the slower the burn. With low octane fuel, the fuel burns quickly and hammers the piston with a quick jolt. With high octane fuel, the fuel continues to burn as the piston moves so there is a constant push to the cylinder throughout the stroke. The engine has to be tuned to take best advantage of this which is why putting high octane fuel in an engine tuned for lower octane fuel is a waste of money, though it doesn't really do harm to use higher octane fuel than the engine needs.

With the higher octane fuel and the engine tuned right, you can get more power out of the displacement. Modern engines do some sort of electronic magic to get massive performance out of small engines. My SOs new Subaru's engine has almost the same power and torque out of its 4 cylinder engine as I get out of my 90s vintage 350 cu inch V-8. My expertise is in embedded processors which do that sort of thing, and I'm still massively impressed. But that's 21st century technology. In the mid-20th century, one of the few options to get better performance out of the displacement you had was to boost the octane.

American engine technology was also better than the Japanese, but that point had already been made. The Japanese surprised the west with the quality of their airframes, but their best engines at the start of the war were licensed copies from other countries. The Sakae engine that powered the Zero was a copy of a Gnome Rhone engine from the French.

The US started the war with the P&W 2800 just going into production. It powered the B-26, P-47, F6F, F4U, and A-26. At the time it was one of the world's largest radial engines and there were two others even bigger in development. The Japanese had lost access to quality foreign engine designs except from Germany and the lifeline to get that technology involved a perilous and long journey. The Japanese had to step up their engine designs on their own and they did develop larger engines and put them into production by the end of the war, but they were still working out the bugs when the war ended.

The US was about 4 years ahead of Japan in engine designs.

The B-26 had a lot more horsepower to work with than any contemporary medium bomber with 2X 2000 HP engines. The B-25 used smaller engines, but it was an excellent and versatile design. It became the predominant skip bomber because it handled like a fighter. North American had some of the best American aircraft designs of the era. Three of the most common WW II vintage planes still flying are NA aircraft: The AT-6, B-25, and P-51.

I can't tell you for sure why the B-25 did have better load carrying capability than similarly powered Japanese aircraft. I've never looked into it. However, if you consult reliable sources that compare the different designs using the same criteria, you will find the load values for the B-25 are generally more than other aircraft with similar horsepower available.

I do know that by mid war at least most B-25s were flying on 140 octane fuel. My father said that a favorite trick guys he knew would do was to fill their cigarette lighters with 140 octane fuel from a small drain on the engine of the B-25 then go into town (this was stateside before he shipped out to New Guinea in late 1943). They would wait until someone put a cigarette in their mouth and offer to light it for them. They would get a flame about a foot long. I would think the lighter would get very hot too. He never did it because he never smoked and never had a lighter, he just witnessed other people do it.

Bill

[geofflambert]

Every time I hear or read the term 'Significant Other' I'm thinking Henry Jekyll is saying it. [:D]