# B-25 modifications



## Maxrobot1 (Feb 25, 2010)

On B-25s, when they moved the turret to behind the pilots and the added package guns and all those nose guns (and the cannon on the G and H models) that must have played hell with the center of gravity compared to the original design. Did these add-ons make the craft nose heavy?


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## FLYBOYJ (Feb 25, 2010)

Maxrobot1 said:


> On B-25s, when they moved the turret to behind the pilots and the added package guns and all those nose guns (and the cannon on the G and H models) that must have played hell with the center of gravity compared to the original design. Did these add-ons make the craft nose heavy?


Ballast was probably added in the tail to keep the aircraft within the center of gravity envelope.


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## Maxrobot1 (Feb 25, 2010)

I know the tail gunner position added some counterbalance and in the Pacific they added a fuel tank behind the bomb bay but I can't imagine just adding dead weight to a combat aircraft!


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## FLYBOYJ (Feb 25, 2010)

Maxrobot1 said:


> I know the tail gunner position added some counterbalance and in the Pacific they added a fuel tank behind the bomb bay but* I can't imagine just adding dead weight to a combat aircraft!*



It’s a common practice to all aircraft. There is a specified CG envelope that must be maintained. Adding ballast (usually lead bars) was and still is a common practice to maintain the CG envelope. Depending on the weight forward of the CG point will determine how much aft ballast in needed. Sometimes only a few pounds way aft of the CG will counter a significant weight forward of the CG.


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## comiso90 (Feb 25, 2010)

Maxrobot1 said:


> I know the tail gunner position added some counterbalance and in the Pacific they added a fuel tank behind the bomb bay but I can't imagine just adding dead weight to a combat aircraft!



Not sure a fuel tank to stabilize the center of gravity is a good idea. an empty fuel tank weighs a lot less than a full one1


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## FLYBOYJ (Feb 25, 2010)

comiso90 said:


> Not sure a fuel tank to stabilize the center of gravity is a good idea. an empty fuel tank weighs a lot less than a full one1


Very true.


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## Colin1 (Feb 25, 2010)

When the Spitfire reached the point of development that required the contra-prop, that required a fair amount of aft ballast in the form of lead bars, the reduction gearbox was a pretty hefty item to have pinned on your nose.


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## DBII (Feb 25, 2010)

My understanding is that the turrent was moved forward because after the waist guns and tail gun was added, it was tail heavy. The early models did not have the waist guns or tail guns. 

DBII


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## Airframes (Feb 25, 2010)

Also, re-location of some electrical and radio equipment to aft of the bomb bay helped the weight and balance. One aspect sometimes overlooked though was performance. When the R.A.F. received Mitchell III's (B25J), they were in service alongside the Mitchell II's (B25C and D) already in the squadrons. Many RAF pilots flying the Mitchell II in formation alongside the III complained that they had to keep 'throttle jockey-ing', thereby using up fuel, to maintain formation, as the III was slower than the earlier II.


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