Helicopter Egg Drop B [Trial]

[knittingfrenzy18]

Well, it should be primarily the design-size and shape-of the blades that will affect your score.

[jander14indoor]

Thanks, but I'm still not seeing how this would decrease times in any noticeable way, considering the weight of the egg. It would seem to me that you would need power to spin the blades fast enough to slow the descent.

It's no different than a glider. The rotor blades are just glider wings turning in a REAL tight circle. As the device drops, air rushes over the rotor, causing it to spin (you do have to tilt the blades a little). As it spins, air goes over the airfoil shaped blades creating lift to offset the weight of the device. As the weight is offset the acceleration down drops. As you accelerate, lift force increases. At some point lift and weight are equal and you descend at a steady velocity. IF you do your part right that velocity will be low and the egg will survive.

Oh, and gravity is your power. You start at one potential energy and end at another. The difference is the energy you have available to slow the descent.

Jeff Anderson
Livonia, MI

[rfscoach]

Clarification on egg placement from UCF Nationals web site:
E. Helicopter Egg Drop: Clarification on egg placement: The egg must be mounted or suspended from the bottom of the device, use a cup provided by the event supervisor, and the cup must hit the floor first. Size of helicopter: No the device may not unfold to a size larger than specified after being released. Dropping the helicopter: The rules state “no energy-producing mechanism of any type can be used to power the rotor(s)”. I would say causing the blades to spin before the drop is using outside energy.

http://www.scienceolympiad2012.com/teams/team-requirements/

[techmaster55]

Finally, some rule clarifications.

[techmaster55]

I would also like to say, in the rules it says that "a" roter may be used, this means that there can only be one rotor on the device correct?

[wlsguy]

I would also like to say, in the rules it says that "a" roter may be used, this means that there can only be one rotor on the device correct?

We tried this at Wright State this year.
Our "Helicopter" had a single blade that went all the way around (think big flat disk made of balsa and covered in a plastic film).
Another way to envision this is to google "Da Vinchi Helicopter".

It effectively turned the "blade" into a parachute.
We then decided it may be DQ's as not in the "Spirit of the Problem" and cut the blade into 2 pieces and created two large blades that almost touched.

The result; our Helicopter dropped slower than everyone elses (highest decent time) but unfortunatley, due to egg placement, the egg cracked.

Do I think it was still legal? No, I think it still was very close to stretching the "Spirit of the Problem".
I'm just hoping these questions get worked out before this becomes an event or it may set the record for FAQs.

[fleet130]

Multiple sets of rules at different internet locations seem to be causing some confusion. My best guess is that the rules at http://soinc.org/sites/default/files/up ... Drop_0.pdf will be the ones used at the national tournament. It's also a good bet the FAQs/clarifications at http://soinc.org/trial_and_pilot_events are what will apply. Hopefully this will all be sorted out in the next day or so!

[techmaster55]

Any national times? I for a fact had the event supervisor tell me I got the best time of the day with about 7 seconds... to bad my egg broke anyway so I got second teired lol they should really fix that when they make the event rules for next year, especially since I think I deserved my medal :p. But whatever nothing I can do now

[knittingfrenzy18]

Hm. We got 15th and our egg broke so I don't know how good that would have been.

[fleet130]

Any national times?

First place team was a little under 6 seconds. Only 2 teams got a better time (approx +.1 & +.6 sec) & both of their eggs broke.

[chalker7]

Any national times?

First place team was a little under 6 seconds. Only 2 teams got a better time (approx +.1 & +.6 sec) & both of their eggs broke.

So having never seen this event run in person, I have one general question. What would make the egg from a team with a slower/longer flight drop time break as compared to a team with a faster/shorter drop time. The rules prohibit cushioning the egg, which must also be the first thing to touch the ground, right? So theoretically the slower the vehicle is moving, the less energy will be transferred to the egg (and making it less likely to break.) I know there is variability in the eggs and egg selection is part of the event, but is there something else I'm missing here?

[fleet130]

What would make the egg from a team with a slower/longer flight drop time break as compared to a team with a faster/shorter drop time.

Several variables determine whether or not the egg breaks.

The first thing that comes to mind is the egg itself. Eggs are not uniform and some have weaker shells or internal membranes. For this reason, teams are allowed to inspect and chose their egg from several provided by the event supervisor.

Another variable is the instantaneous vertical velocity (and horizontal to a lesser degree) at the moment of impact. Overall time reflects the average vertical velocity during the drop. Several factors cause instantaneous velocity to be greater than the average.

.....1. Swinging of the egg increases velocity at points in the swing. Lack of stability caused many of the devices to oscillate from side-to-side,
........much like the stalls exhibited by an improperly trimmed glider.
.....2. When the rotor tips to one side, the lift vector is not vertical, and both vertical and horizontal velocities can increase.
.....3. When a helicopter encounters a downdraft, it's vertical velocity is increased.
.....4. If the rotor is in "ground effect" at the moment of impact, the velocity may decrease.
.....5. Any dirt/dust or irregularity on the floor can concentrate the force of impact to a very small area of the shell.

Depending on how the helicopter is constructed, the egg will have varying amounts of energy to absorb on impact.

Several eggs had cracked shells, but the membrane inside remained intact, thus passing the "paper towel" test.

[The Architect]

I would also like to say, in the rules it says that "a" roter may be used, this means that there can only be one rotor on the device correct?

We tried this at Wright State this year.
Our "Helicopter" had a single blade that went all the way around (think big flat disk made of balsa and covered in a plastic film).
Another way to envision this is to google "Da Vinchi Helicopter".

It effectively turned the "blade" into a parachute.
We then decided it may be DQ's as not in the "Spirit of the Problem" and cut the blade into 2 pieces and created two large blades that almost touched.

The result; our Helicopter dropped slower than everyone elses (highest decent time) but unfortunatley, due to egg placement, the egg cracked.

Do I think it was still legal? No, I think it still was very close to stretching the "Spirit of the Problem".
I'm just hoping these questions get worked out before this becomes an event or it may set the record for FAQs.

I didn't participate in this event, but the people that did said that they got 7.96 seconds and that they were one of the best runs of the day. The egg did break though when it hit the wall and they got 21st place. They used an Aerial Screw (Da Vinci Copter), not seperated into two pieces, and it was allowed.

[fleet130]

but the people that did said that they got 7.96 seconds

By whose clock? I don't have a copy of the spreadsheet available, but I'm pretty sure there were no times over 7 seconds.

[chalker]

but the people that did said that they got 7.96 seconds

By whose clock? I don't have a copy of the spreadsheet available, but I'm pretty sure there were no times over 7 seconds.

That is correct.