Dumbo Ear Size Calculator For Flight     (I know I've Seen Everything When I See An Elephant Fly.)      StreamZones.com

Enter Dumbo Weight: lbs (Dumbo Weight Default Est  - Actual Weight Of Dumbo Is 15,432 Lbs)    
(Airport) Altitude ft (Dumbo Is at sea leve)l    
Minimium Speed mph (Dumbo Glides A Lot)    
Trailing Edge Devices Hinged Flaps (CLmax = 1.8)  
  Slotted Flaps (CLmax = 2.3)  
  Double Slotted Flaps (CLmax = 2.5)  
  No Flaps (CLmax = 1.3) (Dumbo Just Curles Ears)
Cost Penalty:
 %
Leading Edge Devices Leading Edge Slats (20% more CLmax)  
  Leading Edge Slots (10% more CLmax)  
  No Leading Edge Devices (Dumbo Just Curles  Ear Tips)
Cost Penalty:
 %
or
Min Dumbo Wing Area ft^2 Min Dumbo Wing Area m^2
Wing (Ear) CLmax Air Density slugs/ft^3
Weight kg Total Cost Penalty %
Speed kts Speed km/h
Speed m/s Speed ft/s
  (Dumbo Ears Calculator Estimate)

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How large would Dumbo's ears have to be in order for him to fly?

Making a few assumptions:

  1. Dumbo's ears generate lift in exactly the same way as a plane's wings. (i.e. they are perfectly formed into a nice flat level shape)

  2. Dumbo is now a fully grown African Elephant (so i use some data from Wikipedia: http://en.wikipedia.org/wiki/Elephant )

  3. Dumbo is somewhere near as aerodynamic as a passenger jet, and his ears can form parallel to the ground.

  4. Once flying Dumbo is able to maintain the same speed he could on the ground

  5. His ears weight is negligible compared to his regular mass.

Then according to NASA: http://www.grc.nasa.gov/WWW/k-12/airplane/lifteq.html

 

This is the equation we'd need to apply:

L = Lift

C = Lift Coefficient (about 0.3 for a Boeing 747 when parallel to the ground)

D = Density of fluid (1.225 kg/m3 for air, Wikipedia on air)

V = velocity of Dumbo (18 km/h, or 5 m/s according to Wikipedia)

A = Area of Dumbo ears

M = mass of Dumbo (about 7000 kg according to Wikipedia)   (15,432 Lbs)

g = gravitational constant (I'm going with 9.8 m/s/s here)

L= (CxDxV2 xA)/2

Now to generate lift L needs to be larger than the force holding dumbo to the ground, so

L>mg

L>9.8x7000 = 68600 N

Now we rearrange our lift formula

A=2L/(CxDxV2)

Sub in our values assuming we're keeping L to a minimum just to maintain a level flight

A=2*68600/(0.3x1.225x52 ) = 15000 m2 (approximately)

So roughly 15,000 square meters for both ears, 7,500 square meters for each ear. Assuming square wings work well (I'm no aerospace engineer but i doubt this) that's each ear being about 86 meters by 86 meters.

Answer:

86 meters by 86 meters  (86 meters equals 282 Feet)   (Thats a big Dumbo Ear.)

Note: Hopefully someone with more experience and understanding in flight/elephants could better refine this very rough approximation

Flaps are a kind of high-lift device used to increase the lift of an  aircraft wing at a given airspeed. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used for extra lift on takeoff. Flaps also cause an increase in drag in mid-flight, so they are retracted when not needed.

Extending the wing flaps increases the camber or curvature of the wing, raising the maximum lift coefficient or the upper limit to the lift a wing can generate. This allows the aircraft to generate the required lift at a lower speed, reducing the stalling speed of the aircraft, and therefore also the minimum speed at which the aircraft will safely maintain flight. The increase in camber also increases the wing drag, which can be beneficial during approach and landing, because it slows the aircraft. In some aircraft configurations, a useful side effect of flap deployment is a decrease in aircraft pitch angle, which lowers the nose thereby improving the pilot's view of the runway over the nose of the aircraft during landing. In other configurations, however, depending on the type of flap and the location of the wing, flaps can cause the nose to rise (pitch-up), obscuring the pilot's view of the runway.

Dumbo curls big ears to increase the lift needed for take off.    Dunbo also curls the big ears during landing to lower the speed during landing.