Rotor Egg Drop B

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Rotor Egg Drop B

Post by Jim_R » August 4th, 2013, 3:43 pm

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Re: Rotor Egg Drop B

Post by coppersquirrel » October 10th, 2013, 10:21 am

I'm new at ordering materials for science olympiad events and I've noticed that some in the past (on this forum) have recommended Roy White as a source for mylar for helicopters/egg drop in prev. years. Does anyone by any chance have his contact email/phone? I've had no luck trying to locate him on google data search. Thanks so much.

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Re: Rotor Egg Drop B

Post by Alye » October 13th, 2013, 5:34 pm

Did anyone have a succesful design? Any tips? Thanks !

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Re: Rotor Egg Drop B

Post by ebethke » October 13th, 2013, 7:14 pm

I don't want to give away too much science...

But, your design should/could address the forces at play:

Force of gravity pulling the device down.
Force of drag (one of them) pushing up on your device.
Force of lift pulling up on your device

Without a power source Fg > Fd + Fl

But the goal would be to make Fd & Fl as large as possible, and minimize Fg.

So, it would be great to look up what factors modify Fg, Fd, and Fl.

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Re: Rotor Egg Drop B

Post by ebethke » October 13th, 2013, 7:16 pm

Cup or Not?

I ordered the DVD from scioly for the 2012 & 2013 events and it showed the egg in the plastic egg with no cup. These pages here say that there will be a cup.

Which will be true? Does anyone know?

Thank you,
-Erik

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Re: Rotor Egg Drop B

Post by chalker » October 14th, 2013, 5:07 am

ebethke wrote:Cup or Not?

I ordered the DVD from scioly for the 2012 & 2013 events and it showed the egg in the plastic egg with no cup. These pages here say that there will be a cup.

Which will be true? Does anyone know?

Thank you,
-Erik

I infer from your question that you haven't actually looked at the rules for this year, since the answer is very obvious in them. Keep in mind that most events have changes from year to year, so you really need to look closely at the current year's rules before you get too far into preparing for ANY event. LIkewise, the DVD's sold online contain footage from the previous year's national tournament, so often show certain aspects that aren't relevant anymore. However they still often provide a very good insight into designs and techniques that some of the best teams in the country utilize.

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Re: Rotor Egg Drop B

Post by jander14indoor » October 14th, 2013, 10:50 am

Alye wrote:Did anyone have a succesful design? Any tips? Thanks !
Hmm, no designs, but look at the photos from the national tournament. Winning teams obviously had good designs.

But I'd like to take a different perspective than ebethke on the science/theoretical view of the event.

This event isn't about falling its about GLIDING. Properly designed, your rotor system should reach speed quickly where Fg = Fd + Fl. Yes EQUALS!! For most of the flight you should be at steady state terminal velocity so forces MUST Balance. And in the vertical direction at least you should have Fl>>Fd to the point where you can almost ignore the vertical component of drag.

And you most assuredly have a powersource! The potential energy of your system at the start! Think about it, with out power (energy) your rotors would never start turning! And turning rotors are critical to success. Not just from the point of view of the rules, but from the point of view of success. You NEED your rotors to create lift and they can only do that if spinning.

So, what does that perspective tell you on approaching the event?
First, as all flying events, LESS WEIGHT IS KING!! Yes Fg=Fl at steady state, but if Fg is more the only way to get more Fl is to go faster, so your terminal velocity will be higher, ie you'll fall faster.
Second, You must have efficient rotors to generate maximum lift with as little drag as possible. This will minimize your terminal velocity. Check out the Helicopter Duration event for efficient rotor design.
Third, you must get the rotor up to max speed efficiently to use as little of the potential energy (height!) as possible. So now inertial mass in the rotation sense is important. Don't spin anything you don't have too (ie, don't spin the egg!). Keep your rotors light, especially far from the center.

Good luck,

Jeff Anderson
Livonia, MI

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Re: Rotor Egg Drop B

Post by ebethke » October 17th, 2013, 10:32 am

chalker wrote:
ebethke wrote:Cup or Not?

I ordered the DVD from scioly for the 2012 & 2013 events and it showed the egg in the plastic egg with no cup. These pages here say that there will be a cup.

Which will be true? Does anyone know?

Thank you,
-Erik

I infer from your question that you haven't actually looked at the rules for this year, since the answer is very obvious in them. Keep in mind that most events have changes from year to year, so you really need to look closely at the current year's rules before you get too far into preparing for ANY event. LIkewise, the DVD's sold online contain footage from the previous year's national tournament, so often show certain aspects that aren't relevant anymore. However they still often provide a very good insight into designs and techniques that some of the best teams in the country utilize.
Your infer wrongly, we have read the rules several times.

The rules mention a cup several times. The DVD of past events do not show a cup. We understand that events change over time. This is a message board for people to post questions. The addition of a cup would dramatically affect the drop results, in short it seemed to make the event dramatically easier.

So, that would be my more direct question - why was the event modified to be much easier?

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Re: Rotor Egg Drop B

Post by ebethke » October 17th, 2013, 10:35 am

Follow-up question.

Which commercial brand of 3 oz. cup will be used?

Is it a plastic cup? A paper cup?

Here is a plastic solo cup:
http://www.cometsupply.com/mp/SOLO+CUP/pm/SCCP3A/r/ga/

Obviously, we would like to take the science and engineering as seriously as possible and would like to experiment under the most clear test conditions.

Thank you,
-Erik

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Re: Rotor Egg Drop B

Post by ebethke » October 17th, 2013, 10:41 am

jander14indoor wrote:
Alye wrote:Did anyone have a succesful design? Any tips? Thanks !
Hmm, no designs, but look at the photos from the national tournament. Winning teams obviously had good designs.

But I'd like to take a different perspective than ebethke on the science/theoretical view of the event.

This event isn't about falling its about GLIDING. Properly designed, your rotor system should reach speed quickly where Fg = Fd + Fl. Yes EQUALS!! For most of the flight you should be at steady state terminal velocity so forces MUST Balance. And in the vertical direction at least you should have Fl>>Fd to the point where you can almost ignore the vertical component of drag.

And you most assuredly have a powersource! The potential energy of your system at the start! Think about it, with out power (energy) your rotors would never start turning! And turning rotors are critical to success. Not just from the point of view of the rules, but from the point of view of success. You NEED your rotors to create lift and they can only do that if spinning.

So, what does that perspective tell you on approaching the event?
First, as all flying events, LESS WEIGHT IS KING!! Yes Fg=Fl at steady state, but if Fg is more the only way to get more Fl is to go faster, so your terminal velocity will be higher, ie you'll fall faster.
Second, You must have efficient rotors to generate maximum lift with as little drag as possible. This will minimize your terminal velocity. Check out the Helicopter Duration event for efficient rotor design.
Third, you must get the rotor up to max speed efficiently to use as little of the potential energy (height!) as possible. So now inertial mass in the rotation sense is important. Don't spin anything you don't have too (ie, don't spin the egg!). Keep your rotors light, especially far from the center.

Good luck,

Jeff Anderson
Livonia, MI
I concede that Jeff has a much more rigorous answer and lots of excellent specific tips... I was trying to be more vague.

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