# Largest possible navigable blimp

From a pie in the sky approach, similar to the question of whether a jetliner could be theoretically solar powered, what are the limiting factors on the magnitude of lifting capability of a controllable blimp? At what point would the control surfaces be so large that they would be impractically massive? What size would be too large for the fabric? Does a blimp with slightly heavier than air properties have the capacity to be much larger than its lighter than air brother? Anything you can supply would be appreciated.

To remain aloft in air physics of floatation requires total weight to volume ratio should be less than air density as in a LTA blimp.

$$\dfrac{W}{V} < \rho_{air}$$

which also means that percentage increments of weight added should be less than percentage increment of volume.

$$\dfrac{\Delta W}{\Delta V} < \rho_{air}$$

For a neutral balloon floating equilibrium

$$\dfrac{\Delta W/W}{\Delta V/V} =1$$

I cannot understand heavier than air blimps.

• think of heavier than air blimps as flotation-augmented airplanes.
– SF.
Feb 20 '17 at 13:03
• OK. Heavy mounted engine moves it fast to generate lift? Feb 20 '17 at 13:13
• Heavy or not so heavy. It has absolutely enormous lifting area so it doesn't need huge thrust.
– SF.
Feb 20 '17 at 13:20
• Look at the new oddity coming out of Skunkworks. It's a heavier than air blimp aircraft hybrid. Feb 20 '17 at 13:24

This is unanswerable unless acceptable meteorological conditions are defined, and even then it would be exceedingly difficult to calculate.

You can increase the size of the blimp arbitrarily through bundling separate balloons indefinitely, and it will work perfectly well in still air, at any size that doesn't exceed the atmosphere thickness vertically and planet surface horizontally.

But as soon as you add weather it falls apart, as masses of air acting on such object will make it behave more like liquid or gas than a single solid blimp. You need to reduce size before its breaking point. And calculating what kind of winds it can withstand? Obviously it won't be a rigid structure due to the mass overhead restricting the size; it will behave more like one of these huge soap bubbles: and good luck readily calculating breaking point of these!

• But such a monstrosity would hardly be navigable. Feb 20 '17 at 13:29
• @MountainClimberi: Of course! The gap between "largest practical" and "largest possible" is rather huge.
– SF.
Feb 20 '17 at 13:31
• You're right. I changed my question to controllable blimp. Feb 20 '17 at 13:32