Rotor Egg Drop

''Helicopter Egg Drop redirects here. For other Egg Drop events, see Bungee Drop and Naked Egg Drop.''

Rotor Egg Drop is a Division B event from the 2012-2013 in which teams must build and test an auto-rotation device to safely land an egg on the ground from a variable height. Previously called Helicopter Egg Drop, the event's name was changed to avoid confusion with Helicopters. Helicopter Egg Drop was run as a Division B trial event for 2012 in New York and at the National Tournament.

Overview
In this event, you must construct a helicopter rotor device prior to competition. The event supervisor will provide you with a raw egg, a sandwich bag, and a cup. You may request a new egg if you break yours, at a penalty.You have one drop during the competition, and that one drop determines your score for the entire event, so be extremely careful!

The score is determined in several tiers. If your egg does not crack at all, you are in tier 1, which means that you have automatically scored above anyone whose egg cracked. If the egg cracked, but the yolk did not come out, it is in Tier 2. If the egg cracked open and the yolk came out, it is ranked in Tier 3. Within your tier, you are scored based on how long your device was in the air before contacting the ground. Tie-breakers are determined by the weight of the device without the cup and the egg, with lightest device placing above. Most importantly, if in doubt, don't use a design that you think might be disqualified for being a parachute. This MAY include loose rotor coverings. (Depending on judge)

Building the Helicopter Rotor Device
When building the rotor device, you must keep in mind aerodynamic principles, since energy-producing mechanisms are not allowed at all. This includes rubber bands. This means that your design is going to be based solely off of classical physics and how much lift and air resistance you can make with your device. The rotation of the rotors as it falls through the air should cause a difference of air pressure above and under the blades, if the use of "auto-rotation" of the rotor is used. These principles are the ones that are used for the construction of windmills, airplanes, and propellers.

As parachute-like devices are specifically prohibited in the rules, you will be disqualified if your device includes anything like a parachute. While this may close some methods of longest suspension time, this also forces you to create rotors. Many designs include three or four rotors with a membrane that covers these rotors. Other possible designs include the "flower petal" design or the "corkscrew" design. The pitch should be fairly low to gain maximum time.

This event is one in which you must find the balance between super-light, and strong. Your device should be as light as possible, so that it will descend more slowly through the air, however, it also must be strong enough to hold the egg and keep the device stable in the air. If the device is too light it may "sway" as it is falling through the air causing a blade or another part of the device to hit the ground first, rather than the cup that contains the egg.A very common material for the frame of the rotor is balsa wood. Other materials are basswood or carbon fiber rods.

Testing Your Device Before the Competition
Testing is vital to the competition, since you should know whether or not your device works. This way you can modify it to work even better.

Grade A large eggs are defined as at least 56 grams or over. To test, you could drop many eggs to see if your device works, but it could get very messy if your device isn't successful. Another idea is to create a weight that won't drip, so that you can observe the way the device twirls and floats through the air. Anything will do--you can literally take a piece of cloth, bunch it up, and tie rubber bands around it--if it is the same weight as an average egg.

However, you also have to test on a real egg, so you can test if the egg will break or not. This is the messy, but important side to testing. Make sure that the plastic bag is sealed tight when you move to egg dropping.

Competition
The event supervisor will provide you with scissors, a sandwich bag, a cup, masking tape, and an egg. The egg must go in the sandwich bag, which must go in the cup. The cup should be attached to your device in such a way that the cup will be the first thing to contact the floor. Remember that you should not have any air in the bag or any other materials such as wadded up sandwich bag or any masking tape, as it may cushion your egg and result in your device being tiered.

Remember that in competition, you only have one try, so make it count!