And i can tell you with experience that that does not hold up in reality. The crj 900 is a bigger, slightly heavier airplane that uses the exact same engines as the crj700. (CF34-8C5) It holds 76 passengers vs the 65 passengers that the crj700 does. The crj900 has a wingspan of 82 feet and a length of 119 feet. The crj700 has a wingspan of 76 feet and a length of 106 feet. They are also considered sufficiently similar enough by the FAA to be on the same type rating. The 900 while being a larger airplane with the same engines actually has better structural weight limitations. This allows for additional fuel and passengers giving the airplane more range while pilots and dispatchers have more options to choose from.

The crj900 has more or less a basic operating weight of 50,000lbs, a max take off weight of 85000lbs, and a max landing weight of 75100lbs. It burns 2466lbs of fuel per 45mins.

The crj700 more or less has a basic operating weight of 45,600lbs, a max take off weight of 75,000lbs, and a max landing weight of 67,000lbs. It burns about 2252lbs of fuel per 45 mins.

The bigger, bulkier, aircraft that weighs 9.6% more, allows for 41% of the aircrafts total takeoff weight to be devoted to fuel and cargo, a total of 35000lbs.

The crj700 only allows for 39% of its total takeoff weight devoted to fuel and cargo, a total of 29,400lbs.

The crj 900 can thus takeoff with 19.05% additional fuel and cargo, a total of 5,600lbs .

The crj 900 can then land with about 12% more fuel and weight than the 700, a total of 8,100 pounds.

For that 9.6% increase in weight you get almost the exact same amount of increase in fuel burned, which is about 9.05% higher, but you now have the ability to hold 5600 additional pounds of cargo or fuel.

I'm not even going to go over weight and balance, but that's not really that big of a problem as you're going to design your aircraft, or in thise case, lam, with this in mind...

The structural weight limitations between the 700 and 900 proves that a slight increase in bulk, with the same engine AND EVEN MORE WEIGHT (unlike how it is in battletech) proves this is not as big of a problem as you think it is.

PS: the seatbelt sign is not turned on due to weight and balance concerns. It's turned on so that people don't turn into projectiles in turbulence, or get hurt.

and does it change shape, Sledge?

no, seriously, is your aircraft example a variable geometry airframe that can also serve as a helicopter and a tank?

this is what we're talking about with LAMs- a variable geometry airframe that can also serve as a light tank and an attack helicopter.

The adaptations you cite, are for a fixed airframe with what can be generously termed stable dimensions.

The Land-Air-'mech is a 1980s Transformer (or Veritech, if you go with the Macross series as your guide, aka Robotech for those of us who watched it as kids in the early eighties.)

You're shifting a hell of a lot more geometry, and something's gonna give. The limitation makes sense because all that conversion gear is going to be bulky and it's not going to get LESS bulky using bulkier materials and a larger structure because of the square-cube law.