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Re: Helicopter Egg Drop B [Trial]

Posted: May 25th, 2012, 6:05 am
by 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?

Re: Helicopter Egg Drop B [Trial]

Posted: May 25th, 2012, 8:58 am
by 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.

Re: Helicopter Egg Drop B [Trial]

Posted: May 25th, 2012, 5:04 pm
by 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.

Re: Helicopter Egg Drop B [Trial]

Posted: May 25th, 2012, 10:19 pm
by 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.

Re: Helicopter Egg Drop B [Trial]

Posted: May 26th, 2012, 7:07 am
by 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.

Re: Helicopter Egg Drop B [Trial]

Posted: May 26th, 2012, 12:48 pm
by The Architect
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.
I believe you, I thought that it was a very long dissent time also. I am just relaying what I was told.

Re: Helicopter Egg Drop B [Trial]

Posted: May 27th, 2012, 10:40 pm
by Itsanthonguise
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

Well my dad timed it and he said that the one i made was 5.3 seconds and i got 6th place at nationals :D

Re: Helicopter Egg Drop B [Trial]

Posted: July 17th, 2012, 8:25 pm
by himlynx
Since there is no standard height from which the helicopter is dropped, these comparisons of time of descent are not meaningful

Re: Helicopter Egg Drop B [Trial]

Posted: July 17th, 2012, 8:35 pm
by himlynx
This event is new and the rules appear to be tentative. I have the following questions :
1. Is it OK to have damage to the helicopter when it lands ?
2. Any restriction on materials that can be used ?
3. Are we permitted to have more than one rotor, one above the other ?
4. Any restriction on number of blades per rotor ?
5. Will the cup holding the egg be supplied by the event organizers ? Or the contestants build it ?
6. What if the helicopter lands at an angle and a rotor blade touches the ground before the (egg holding) cup ?


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B Division Coach 2012 : Shock Value (Gold at NC State) & Bottle Rocket (Silver at NC State)

Re: Helicopter Egg Drop B [Trial]

Posted: July 17th, 2012, 8:44 pm
by himlynx
I have two suggestions :
1. In order to get clearance from walls and similar obstructions, the helicopter could be dropped from the end of a rod,say, about 2 meters long. A hook at the end of the rod could engage a hook or a loop on top of the helicopter. The helicopter could be dropped by turning (rolling) the rod 180 degrees.
2. The rules refer to aerodynamic drag on the helicopter "blade. " A single blade cannot make a helicopter. A minimum of two are required. All the blades in a plane are together called a "rotor." Therefore, the term "blade" should be replaced by "rotor(s)."


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B Division Coach 2012 : Shock Value (Gold at NC State) & Bottle Rocket (Silver at NC State)