MadSci Network: Engineering

Re: Which airplane wing will fly the farthest?

Date: Mon Dec 13 11:03:29 1999
Posted By: Adrian Popa, Directors Office, Hughes Research Laboratories
Area of science: Engineering
ID: 944965597.Eg


Airfoil design has been a continuing topic for study ever since the Wright 
brothers first aircraft. Also the ability to use models to test designs has 
always been part of aerodynamic engineering so your experiments are 
following in the foot steps of all of the great aeronautical engineers. 

It turns out that maximum lift and maximum distance are not the same thing. 
Many factors influence the design of an optimum airfoil. These factors 
include the weight of the payload and fuel load. The speed and range desired 
for the aircraft. Takeoff and landing lengths and so on.
Each wing design must be optimized based on these factors. Thus it is 
difficult to answer your question directly for each wing that you tested  
had a different weight, lift to drag ratio and they probably flew at a 
different velocities.

Also modern aircraft have the ability to greatly modify the shape of the 
wings during different portions of the flight. Thus we have flaps and slots 
for takeoff and landing and swing-wings for changing between subsonic and 
super sonic flight.

From your note you are measuring only distance as an experimental parameter. 
The key parameter in your experiments is the glide ratio. That is for each 
meter (yard) of height at launch how far in meters (yards) will the aircraft 
fly. Glide ratios can be more than 20 to 1 for gliders and as little as 1.5 
to 1 for the Space Shuttle. Airliners with trimmed wings (no flaps or wheels 
down etc) have a glide ratio of about 10 to one. If flaps are used for 
increased lift, the aircraft will land with a lower velocity but will also 
have a decrease the glide ratio. That is they land in less distance and at a 
slower speed, which is what you want to do for landing. 

The optimum design for maximum glide ratio is the long thin wing used for 
gliders, and the U-2 and TR-2 reconnaissance aircraft.
The solar electric Pathfinder aircraft now being flown by NASA is all wing 
and it carries a battery and solar cell payload. This design for a slow 
aircraft that will fly at great heights for many days or weeks is a very 
interesting compromise between gliders and payload carrying airfoils. You 
can read about this project at: 

You will find much interesting information on experiments similar to yours 
on the following web sites. The one on flying squirrels and other animals  
is quite interesting:

Good luck with your future experiments.

Your Mad Scientist

Adrian Popa

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