Can a helicopter land in water?

when they crash in the water they certainly can - of cousre there is the mythical flying sub from "voyage to the bottom of the sea" - it is possible to make a winged craft or lifting body that would "fly" underwater but its ineffecient since underwater craft dont need to fly as it is more effecient to make them bouyant - wings are used in subs in the form of control surfaces

if one were to design a "flying sub" then the design from "voyage" is probably the most practical using a lifting body design - wings would be too fragile due to the heavy weight of water creating huge forces on the wings

Bathtube AerodynamicsYes. By this I mean that a plane can "fly" under water just as it does in the Air. In the 1960's, a professor at Mississippi State University, Professor August Raspett, helped design STOL vehicles and was involved in other aerodynamic research. Today the aerodynamics lab located at the local airport is named after him.

Professor Raspett and his young son wrote a technical paper called "Bathtube Aerodynamics". It was actually his son's idea and his father assisted. The son wanted to take a model airplane and try to fly it in the water. The typical model he used was the scale plastic models----or as you would call them---plastic kits. It actually works. Why? The equations for fluid flow is the same for AIR as it is for WATER. Only the Reynolds Number changes.

First you have to trim the model for proper CG. Plastic kits are built to scale but the model is not have correct Center of Gravity. Some models had to be altered. Some holes have to be plugged. For example: a model of a jet may have a large opening for the engine inlet which may require plugging to prevent disruption of the flow. The wings and tails have to be perfectlly aligned so they will produce lift. If it had a propellor, then it had to be removed to reduce drag. The model can then be launched under water and it will glide just like it was in AIR. Since the Reynolds Number for water is higher, the model will "fly" slower in water---but it will still fly.

He also tested different models using rubber-band powered propellors. And they could glue some chemical(forgot what you call it) to the model and as it went through the water it would leave a blue contrail left from the chemical exposure to water. This could be used to study the votex and airflow.

Really cool. Possibly a great idea for a high school science project.

Link to a list of technical papers by Professor Raspet that includes "Bathtube Aerodynamics"

http://w3.gwis.com/~mks/book.htm

Other Related Links

http://www.ae.msstate.edu/rfrl/pages/capabilities.html

http://www.aiaa.org/content.cfm?pageid=406&gTable=Paper&gID=45046

Photo XV-11 Marvel designed by Dr. Raspet and MSU.

http:/www.aerofiles.comMSU-xv11a.jpg

MORE ABOUT "BATHTUB" AERODYNAMICS

some fish actually fly like airplanes - fish like sharks have no swim bladder to keep them bouyant so have to stay in motion, or fly, to keep from sinking - many like the shark have bodies that are lifting bodies and their fins can act like wings to give extra lift - think of the manta ray as the ultimate marine aircraft.

Also Penguins and even ducks can "fly" underwater. Of course they have the advantage of flapping wings instead of fixed wings.