Rotor Egg Drop B

[WellwoodLands]

Hello to all,

Just out of shear curiosity and for the mortal well being of my egg, do the rotors during the 2013-2014 Science Olympiad competition have to spin on its' and axis' or does the axis have to spin along with the rotor?

-Thanks!
-Newbies of 'MERICA

[_HenryHscioly_]

I one-bladed rotor egg drop could work...correct?
Add mass to other side to balance(concept: use integral of distance*mass and make sure both sides are equal)?

Or is this wayyy off for rotor egg drop...and I should start with 3, 4, or even more blades..

[lklansingkiter]

I am in charge of getting some kids going on rotor egg drop competition and I don't see any official rules about what the limitations are on building the rotor except some reference to non parachute like. This is the only rules I found online http://scioly.org/wiki/index.php/Rotor_Egg_Drop which doesn't specify a size. I hear people on this thread talking about it must fit in a 51x51x51 cm cube but what exactly does this mean and where is it written. There are all kinds of combinations of folding wings and orientation that may or may not meet this criteria depending on how you interpreter it. Why aren't the rules written in concrete so we have something for a design basis.I also found this" Most importantly, if in doubt, don't use a design that you think might be DQ'ed for being a parachute This MAY include loose rotor coverings. (Depending on judge)" . I wish they would write a concrete definition of what a parachute is. A paraglider could be defined as a parachute to some and looks like a parachute but it has an L/D of near 8 to 1 and the distance record is now over 500km and is clearly not a parachute in terms of aerodynamics . So this is based solely on some arbitrary definition of what some judge decides is a parachute?

Larry

[edit]

[goodcheer]

[quote="WellwoodLands"]Hello to all,

Just out of shear curiosity and for the mortal well being of my egg, do the rotors during the 2013-2014 Science Olympiad competition have to spin on its' and axis' or does the axis have to spin along with the rotor?

Most of the examples I have seen use an imaginary central axis. The earth rotates around an axis (imaginary line). You might be thinking of an axle, which is similar but not the same as axis. The rules speak of a "central axis." But since you mention it, I suppose you could have a device which turned around an actual axle. It does seem, however, such a device would be heavier than one with an imaginary axle.

Also for lklansingkiter (Larry) and others pondering the same thoughts:

The written rules manual contains all the official rules. Rule 3e speaks of the 51 cm cube. It means your device must not be greater than 51 cm in any direction. Measure it left to right, front to back, and top to bottom with cup attached and make sure each dimension is 51 cm or less.

As for your question about wing design and avoiding a parachute, you are right about there being all kinds of possible designs. An important rule about the wing design is contained in 3a: the device must not be or contain an airplane, a balloon, or a parachute. The concern expressed here would be to avoid any appearance of a parachute. A paraglider is by its own terminology a parachute/glider. So it would seem that any device that had wings that captured air like a paraglider would be like a parachute. Also, this device must rotate unlike a glider. The way the rule reads the only things allowed to slow the descent of the egg are "aerodynamic principles of a helicopter rotor in unpowered, autorotation mode." Specifically excluded from the device: airplane, balloon, parachute. Part of the confusion perhaps arises from the fact that all of these use "aerodynamic principles" to operate. Yet, we are limited in this event to how these principles are utilized. I say this in defense of the rules because that is what we all have to follow. Also in defense of judges, if one says your device is acting like a parachute then your egg is cooked even if it didn't break. Seriously, you shouldn't be DQ'ed, but placed in a lower scoring tier.

[lklansingkiter]

Thanks for your reply . I am still having trouble finding the rules. Could someone please show me the link.

I also want to offer a differing opinion on the subject of what is" parachute like". A paraglider is not a parachute and not operation as a parachute it is an airfoil that converts the downward motion through the air from gravity into lift that pushes it forward . It we take the extreme example of a speed glider http://en.wikipedia.org/wiki/Speed_flying . The speed glider flies at speeds of 20 to 90 mph verses a paraglider's 12 to 50 mph.[5]. The speed glider looks like a paraglider and looks like a parachute yet flies with a forward airspeeds of up to 90mph. There is no way at these speeds that you can say this type of airfoil is a parachute that is working by "capturing air". If you followed one molecule of air passing under the wright brothers airfoil at 25mph and a speed gliders airfoil at 90mph you would have to conclude that the wright brothers airfoil was holding that molecule longer and therefore capturing the air more than the speed glider. Yet the speed glider would be considered a parachute to some who don't look a the physics. If you where to look at how shallow the angle of attack of a speed glider going 90mph or paraglider going at top speed is you would have to conclude that it is operating as an airfoil not a parachute. I guess this is all a moot point unless enough people demand a clarification to what is "parachute like".

[iwonder]

The rules are not online, it's a copyright violation to post them. The coach for the team you're with should be able to get you a copy from the rules manual they were shipped when they registered.

[jander14indoor]

Your head coach has one manual if they registered their team and paid the fee. They are authorized to copy pages for the teams use as needed, this includes event coaches/mentors. No one is authorized to post them on line (as already mentioned).

You (or anyone) can also order rule books directly form the national organization's website in their store. Here's the link to the Div B rules which includes Rotor Egg Drop in addition to the 22 other events. http://store.soinc.org/p-13-2014-rules- ... ion-b.aspx

As far as the seeming ambiguity of parachute, I'm with you, loose covering on a wing does NOT constitute a parachute when you can show that the relative air flow is pretty close to parallel with the surface, not perpendicular to it like a parachute. BUT, the national event supervisor did not rule that way last year, and local ES may not this year. Easy to avoid the problem though as long as you are aware of it.

And be aware, these rules are written by dedicated, hardworking volunteers. We/they do their best to avoid ambiguity, but since they are revised on a regular basis, something always seems to creep in. Writing good rules is WAY harder than you might think. Just treat it as part of the problem. If too vague, you can always ask a clarification question, sometimes the answer will narrow down the problem, sometimes not. If not, just consider THAT part of the problem. Sometimes we intentionally make things ambiguous to leave room for students to innovate. I mean these things ARE meant to challenge the students afterall.

Oh, and if you haven't looked there yet, check out the Helicopter Duration thread. Many good design ideas to make efficient rotors there that can be directly transferred to this event.

Jeff Anderson
Livonia, MI

[goodcheer]

im confuzzled, can we use a cup?

The cup will be supplied at the event. But in order to practice at home, you have to use a cup: according to the rules, a 3 oz paper cup. When you get to the event, you will attach the cup that is supplied to your pre-made device. For example, your device might have three strings hanging down which you attach the cup to. Masking tape will also be supplied for this purpose.

[helicpters_rule]

Whats a good time for this event i am new to it.

[helicpters_rule]

What is a good substitute for Mylar that i can get easily.