Helicopter B/C [Trial]

User avatar
brobo
Exalted Member
Exalted Member
Posts: 445
Joined: April 8th, 2009, 2:44 pm
Division: C
State: TX
Location: MINECRAFT!
Contact:

Re: Helicopter B/C [Trial]

Postby brobo » April 19th, 2010, 3:53 pm

OH CRAP
I just got put into this event today and State is on FRIDAY!!! Luckily my partner is Chlorine Kills who is pretty good at building stuff, but I have no clue about how a helicopter works! He has a little idea, but still....

So I need advice. What is the best way to approch this event? What is a good design that we could build in a few hours? We are not looking to place, just get anything above last. I don't care if it flies for 5 seconds, I just want it to fly. If we design our own, what should it kind of look like? Are there key components that we should put on it?

I know its a lot, but any help would be greatly appreciated.
Image--Texas!

brobo's Userpage

"Let's put all our differences behind us, for science. You monster."

Ubuntu is awesome.

User avatar
smartkid222
Exalted Member
Exalted Member
Posts: 774
Joined: June 22nd, 2008, 8:12 am
Division: C
State: NY
Location: Western Long Island
Contact:

Re: Helicopter B/C [Trial]

Postby smartkid222 » April 19th, 2010, 6:32 pm

http://www.illinoisolympiad.org/iso/fil ... copter.pdf
look at that if you haven't. Can't really say too much else to help.
If you end up with NOTHING, get materials that meet the construction requirements and throw it up into the air as high as you can. It will get you out of last place.. trust me, i've seen it done before LOL.
Image 2008 NY BLG Champ
2010 NY Helicopter Champ

jander14indoor
Member
Member
Posts: 1553
Joined: April 30th, 2007, 7:54 am
State: -

Re: Helicopter B/C [Trial]

Postby jander14indoor » April 19th, 2010, 6:37 pm

As usual, READ THIS STRING BACK A FEW PAGES!!! Sorry for the shouting, but really, 10 pages, 136 notes and you ask for an explanation? At least cite things you didn't understand.

OK, off high horse. Go back a page or two in this string and see my note pointing to some pages for designs.

Now, only a couple of days. SIMPLIFY! Use flat plate blades for your rotor, concentrate on keeping the weight LOW, as close to 4 gm as possible. Allow about 1 gm for each of two rotors, 2 gm for motor stick and rubber hooks. Pick and angle, say 20 degrees for the blades, make sure they are counter rotating and TRY it. You might be surprised.

Hope that helps a little.

Jeff Anderson
Livonia, MI

jander14indoor
Member
Member
Posts: 1553
Joined: April 30th, 2007, 7:54 am
State: -

Re: Helicopter B/C [Trial]

Postby jander14indoor » April 19th, 2010, 6:40 pm

Careful of the Illinois sample design. The plastic blades aren't legal under the trial rules as written on the national site, nor as used in most state. It will of course depend on your event supervisor's interpretation, but I thought it was pretty clear, and even Illinois explicitly clarified the rules to allow plastic in their contest.

Now, replace the plastic with flat plates of wood, or even better, warped plates, and there you go.

Jeff Anderson
Livonia, MI

SOCoach
Member
Member
Posts: 115
Joined: January 16th, 2003, 6:08 am

Re: Helicopter B/C [Trial]

Postby SOCoach » April 19th, 2010, 7:11 pm

Do the wings on the helicopter need to have airfoils like the wing of a wright stuff plane, or simply flat with a twist? I guess I am not sure how it generates its lift . . . . simply by moving the air?

SOCoach
Member
Member
Posts: 115
Joined: January 16th, 2003, 6:08 am

Re: Helicopter B/C [Trial]

Postby SOCoach » April 19th, 2010, 7:13 pm

Oops . . . sorry Jeff, should have read the post above mine . . . so flat blades with an approximate 20 degree tilt.

jander14indoor
Member
Member
Posts: 1553
Joined: April 30th, 2007, 7:54 am
State: -

Re: Helicopter B/C [Trial]

Postby jander14indoor » April 20th, 2010, 3:33 am

Do the wings on the helicopter need to have airfoils like the wing of a wright stuff plane, or simply flat with a twist? I guess I am not sure how it generates its lift . . . . simply by moving the air?
No problem, and actually a good question.
Ideally, the blades (or wings) of your rotors should be airfoil shaped and have a twist as they do create lift, just like a wing. Problem is, they aren't operating in a uniform velocity field like a wing, even if the air is flowing as a body uniformly past or through the rotor. The tips are moving much faster through that field than the hub so need different angles to have an appropriate angle of attack.
But, just like Wright Stuff, they will work even if flat, if angled properly. And even if not twisted. Just not as efficiently. The poster I was answering with the flat blade suggestion wanted a quick and dirty solution to a working copter in four days. Flat is quick, dirty and inefficient aerodynamically, but quick. And it will fly better than you expect. I was getting 30 seconds with last years trial rules and flat blades. No where near the capability of these things, but it flew. Thirty seconds would have one a lot of regional trials I saw this year. Probably not so much next or the year after when the students get things figured out.

Oh, side comment. ALL wings generate lift by moving the air. For the plane to go up, it HAS to push the air down, equal and opposite reactions and all. The shape of the airfoil just helps some do it more efficiently than the others. The trick is to keep the wing (or rotor) moving in a stable, consistent fashion.

Thanks,

Jeff Anderson
Livonia, MI

jander14indoor
Member
Member
Posts: 1553
Joined: April 30th, 2007, 7:54 am
State: -

Re: Helicopter B/C [Trial]

Postby jander14indoor » April 20th, 2010, 5:18 pm

I love the internet. For all those who've been asking for some idea of what a good helicopter to these rules looks and flies like here's one from this year on youtube: http://www.youtube.com/watch?v=5RwygrzF ... re=related

As you can see, it does fly. Needed more power/winds, don't know if the pitch was right on the rotors, or what the overall weight was, but it LOOKS like what at lease one successful design looks like. Probably capable of MUCH longer flight times if tweaked correctly.

Jeff Anderson
Livonia, MI

User avatar
brobo
Exalted Member
Exalted Member
Posts: 445
Joined: April 8th, 2009, 2:44 pm
Division: C
State: TX
Location: MINECRAFT!
Contact:

Re: Helicopter B/C [Trial]

Postby brobo » April 20th, 2010, 6:55 pm

Crunchtime! I'm really worried right now about the design of my helicopter... most of my doubt is probably just nerves, but can anyone give me some pointers as to if my design is good? I'll do my best to describe it.

Not including the propeller/rotter, our helicopter is about 15 cm tall. It is a triangular prism in shape, with each side of the triangle measuring 7 cm. I built some supports in the shape of X's on each side to stabilize it and keep it from breaking. We have a piece of paper covering the upper end, and that is where our rotter is. It has two blades, each 15 cm long, completely flat, and tilted to about 20 degrees. I'm not sure what my partner is planning, but we will attach the rubber band to the bottom of the helicopter, and the other end to the bottom of the rotter, and spin the blades to wind it up. All together, our helicopter weighs about 8 grams (a little heavy, I know).

Any thoughts? Too heavy? More blades? Any input is greatly appreciated. Thanks!
Image--Texas!

brobo's Userpage

"Let's put all our differences behind us, for science. You monster."

Ubuntu is awesome.

User avatar
smartkid222
Exalted Member
Exalted Member
Posts: 774
Joined: June 22nd, 2008, 8:12 am
Division: C
State: NY
Location: Western Long Island
Contact:

Re: Helicopter B/C [Trial]

Postby smartkid222 » April 20th, 2010, 7:18 pm

WTH! Thats my partner at regionals! i dont remember anyone taking video. Gah. oh well lol

I would say that it needs to be lighter. What materials is everything made out of? do you mean actual lined paper?
but more importantly i guess... does it fly?
Image 2008 NY BLG Champ
2010 NY Helicopter Champ


Return to “2010 Build Events”

Who is online

Users browsing this forum: No registered users and 1 guest