Can tail wing increase and main wing decrease(so they're equal size) achieve same total lift?

Question

Thinking that though is not happening every day, collisions with other planes wing during pushback/taxi occur here and there, and also that the wing size limits the parking/gate space specially for big airliners and small/crowded airports, I thought if designing an airplane in a way so that you could reduce the main wing span and increase the tail wing span so they are equal and as a result the aircraft's maximum span is reduced, then would this help to alleviate the problems described(collision and parking size)?

Would this work, or the pros would be less than the cons?

Answer 1

Yes, same total lift can easily be achieved by 2 pairs of wings - or 3 pairs, or more, as in the Caproni Ca.60 above. But there is a reason why monoplanes are in fashion, as mentioned in this answer: drag.

The two well known basic subsonic equations:

$ L = C_L \cdot \frac {1}{2} \rho \cdot V^2 \cdot S \tag{Lift} $

$ D = C_D \cdot \frac {1}{2} \rho \cdot V^2 \cdot S \tag{Drag}$

With S being the wing area, in whichever shape. But for the drag coefficient $C_D = C_{D0} + \frac {C_L^2}{\pi A e}$, the wing aspect ratio $A$ plays a large role in induced drag, as per this answer.

Dividing a wing area into two or more pairs of wings reduces their aspect ratios, and creates more induced drag than just one single pair of main wings, with as high an aspect ratio as structurally possible.

Answer 2

There is a loss of efficiency as now one essentially has a bi-plane. However, one should not ignore this design as it may allow for higher aspect wings.

Design proposals for "trussed-braced" wings could be further developed.

Bi-planes undeniably can generate more lift at the same speed than monoplanes, which may be useful in applications such as military cargo transport.

Very large bi-planes have not been tried in over 100 years. The ones that were built were said to fly well.

Answer 3

An overarching consideration for a commercial airliner designed to be used at gates is that aerodynamics, while important, can’t be, well… overarching all other requirements.

General Challenges of Dividing One Wing into Two:

• Duplicity of systems (cost, weight, complexity)
  o Flaps
  o Ice Protection
• Thinner wings (assumes t/c_max ~same, resulting in smaller t_max's)
  o Gear integration disadvantages
  o Less thickness for flight control actuators

Challenges Unique to One Wing Aft of the Other:

• Gear integration (e.g., neither wing will likely be near a good rotation point)
• Ground footprint has less maximum width but consumes more area
  o Maneuvering GSE around aircraft perimeter
• Stability & Control
  o Requires statically unstable aircraft in pitch for both wings to be lifting
  o Regulatory hurdles
  o Technical and safety risks
• Propulsion Integration
  o Will want the weight of the engines between the wings
• Wake/downwash effects of forward on aft wing

Challenges Unique to One Wing Over the Other:

• Highly coupled lifting surfaces in transonic flight
• Structural issues with flexible high aspect ratio wings, one over the other

In summary, it’s theoretically possible but there exist serious (insurmountable?) challenges in creating a workable system solution.

Answer 4

Also, consider that one wide span wing gets to deflect a wide swath of air while two tandom wings of half the span both deflect the same swath of air. The latter is effectively half the aspect ratio which results in higher induced drag and resulting fuel use.