Rotor Egg Drop B

[Skink]

Of course not! This board is for open discourse on Science Olympiad, and this includes the rules (within reason, of course ). If I came off as antagonistic in any way myself, I did not intend it. Like you, I (and many other division B parents, coaches, and supervisors) have been trying to figure out this event since the rules manual came out.

[chalker7]

But since it was downgraded, on undefined criterion of how a cover should behave during descent, how about adding that (and only a suggestion), device must have spaces (how much length, width, height) between each rotor. Covering on rotor must not be raised more that X-cm when descending. Should two covered rotors be attached with each other or should they be completely free of next rotor? but once it is defined, then the discretion of supervisor should be limited to look for these specs only and not add their own undefined criterion. It can make the judgement process very un-predictable.

I'm not trying to be difficult, but how would you suggest accurately and easily measuring the suggested rule of covering not being raised more than X-cm during descent. I agree that the current wording is ambiguous, however I'm not entirely sure there is a more definite wording that is also allows for realistic competition day logistics. When writing the rules we obviously strive for fairness and clarity, however concessions occasionally have to be made in order to permit the event to be run in as many tournaments as possible. We're always open to suggestions and will take those suggestions into account with the next round, but please realize there are many considerations involved.

[saurabhg47]

But since it was downgraded, on undefined criterion of how a cover should behave during descent, how about adding that (and only a suggestion), device must have spaces (how much length, width, height) between each rotor. Covering on rotor must not be raised more that X-cm when descending. Should two covered rotors be attached with each other or should they be completely free of next rotor? but once it is defined, then the discretion of supervisor should be limited to look for these specs only and not add their own undefined criterion. It can make the judgement process very un-predictable.

I'm not trying to be difficult, but how would you suggest accurately and easily measuring the suggested rule of covering not being raised more than X-cm during descent. I agree that the current wording is ambiguous, however I'm not entirely sure there is a more definite wording that is also allows for realistic competition day logistics. When writing the rules we obviously strive for fairness and clarity, however concessions occasionally have to be made in order to permit the event to be run in as many tournaments as possible. We're always open to suggestions and will take those suggestions into account with the next round, but please realize there are many considerations involved.

measuring close to accurately, may not be too difficult, the looseness (that can further help determine how much it may be raised during a descent) of a covering can be measured at the time of other inspections, such as, weight, size, etc.

However, I believe I understand current standing policy, the event supervisor is trusted with judicious discretion. The discretion may differ from event to event, supervisor to supervisor, and participant will be at mercy of those discretion. That's all I was trying to understand, if there is a possibility of having more specifics (which, like you said, the suggestions will be taken into consideration for next rounds).

Thanks for the response,

With warm regards

[rmp509]

hey i was wondering what was considered a parachute. if i left the plastic wrap loose on my rotors would that count as a parachute? to what extent does it count or not count as a parachute?

[Skink]

Check out the FAQ on the matter.

Unfortunately, we do have word at the National level as to what constitutes a parachute. Actually, it's a bit unclear because it leaves the question up to the supervisor's discretion. That said, it seems being as conservative as you can in your definition of 'parachute' is your best option, and design your next device with that in mind, whatever the most unreasonable supervisor would DQ or Tier ? you over.

[abby1kanobe]

Per WIKI:


A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon. Parachutes must slow an object's terminal vertical speed by a minimum 75% in order to be classified as such. Depending on the situation, parachutes are used with a variety of loads, including people, food, equipment, space capsules, and bombs.

As I read it, every single Egg Drop vehicle could be considered a parachute.

So, by definition how can one build an egg drop device that would not be able to be defined as having the characteristics of a "parachute"??? To me an event judge could use his/her discrection to DQ any Egg Drop device if they liked. In some state tournaments leaving this area so grey could lead to teams winning or losing a state title to an interpretation of a very vague definition.

[rmp509]

Per WIKI:


A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon. Parachutes must slow an object's terminal vertical speed by a minimum 75% in order to be classified as such. Depending on the situation, parachutes are used with a variety of loads, including people, food, equipment, space capsules, and bombs.

As I read it, every single Egg Drop vehicle could be considered a parachute due to the fact that the device is always falling and at no time is there vertical lift occuring, just a decrease in decent based on shape and design of rotors.

So, by definition how can one build an egg drop device that would not be able to be defined as having the characteristics of a "parachute"??? To me an event judge could use his/her discrection to DQ any Egg Drop device if they liked. In some state tournaments leaving this area so grey could lead to teams winning or losing a state title to an interpretation of a very vague definition.

yea this really is a very vague statement. i think i am going to find a in between area on my egg drop

[_HenryHscioly_]

Lift is the component of this force that is perpendicular to the oncoming flow direction.

It contrasts with the drag force, which is the component of the surface force parallel to the flow direction.

-Wiki


the force slowing it down is upwards, and the blades or rotating on horizontal plane,
the slowing-down of the rotor egg drop and the movement of the blades are perpendicular, and therefore -> lift

[Sherry Berry]

Could someone please explain "spars" and "pitch" to me, in terms of this event? No one on my team seems to be able to explain it very well, and I've never done a building event before so I'm still trying to figure things out. Thanks.

[jander14indoor]

Spars are the long structural members of your rotor blades, running from the center to the tip.

Pitch. At its simplest think of your rotor as a giant screw. Again, at its simplest, the pitch of your rotor is the distance it would travel through a solid in one turn if it were a screw.

Propellor designers talk about pitch as if it were the real way the propellor (rotor) behaved because its easy to visualize and describe the physical rotor. In reality it doesn't move like a screw through a solid, there's a lot of 'slip' and the rotor doesn't move through the air as far as its geometrical pitch says. But it does describe the blade phsyically and allow comparisons. And when detailed analysis is done, all that slip stuff is taken into account.

See some of the following sites:
http://www.pilotfriend.com/training/fli ... /props.htm
http://www.allstar.fiu.edu/aero/flight63.htm
http://members.eaa.org/home/homebuilder ... lemma.html

Note, I sent you to sites about propellors as they were quicker for me to find. There is NO difference between a propellor and a rotor from a how they work point of view. Just how they are used.

Jeff Anderson
Livonia, MI