Elastic Launched Glider C

Jim_R
Admin Emeritus
Admin Emeritus
Posts: 283
Joined: May 13th, 2001, 4:22 pm
Division: Grad
Location: Pittsburgh, Pa
Contact:

Elastic Launched Glider C

Postby Jim_R » August 14th, 2012, 7:32 pm

-The path of the Administrator is beset on all sides by the inequities of the selfish and the tyranny of evil men.

-Nothing\'s gonna get deleted. We\'re gonna be like three little Fonzies here. And what\'s Fonzie like? Come on, what\'s Fonzie like?
-Cool?
-Correctamundo. And that\'s what we\'re gonna be. We\'re gonna be cool. Now, I\'m gonna count to three, and when I count three, you let go of your mouse, and back away from the keyboard. But when you do it, you do it cool. Ready? One... two... three.

User avatar
chia
Member
Member
Posts: 558
Joined: January 13th, 2009, 5:09 pm
Division: Grad
State: IL
Location: Derse

Re: Elastic Launched Glider C

Postby chia » August 30th, 2012, 2:48 pm

Whoa, thanks for the nice list of forum links, that'll come in handy for sure!

I have a question already: what kinds of spaces will you use for flight trimming? Seems you need a gym, large hall, auditorium, etc., like for Wright Stuff, though Helicopter could technically be tested on an 8-foot ceiling. I'm having trouble finding a readily available testing place; school lunchroom/gyms/etc. are always in use, nearby elementary school's aren't big enough or open for use when I want it to be...
(avatar is by xamag)
Favorite events: Anatomy, Microbe Mission, Ornithology, Circuit Lab, Helicopter
NCHS '13
==>

retired1
Member
Member
Posts: 671
Joined: July 25th, 2012, 5:04 pm
Division: Grad
State: FL

Re: Elastic Launched Glider C

Postby retired1 » August 30th, 2012, 3:45 pm

Soinc is a redheaded stepchild at my schools. Athletics of any kind are king! I wonder how it is in Solon, OH?
It will not be an event at our regional at this time, so the students will have to prepare for state with a 35' cluttered ceiling. It will take a lot of begging and whining to get the gym and then it will be at very inconvenient times. Everybody else with a high ceiling wants money!
We will probably do some testing outside in calm weather. Being in FL it is somewhat doable.
My church let me do choppers, but it is nowhere big enough for gliders.
Good luck.

twototwenty
Exalted Member
Exalted Member
Posts: 292
Joined: March 24th, 2011, 10:28 am
Division: Grad
State: NY

Re: Elastic Launched Glider C

Postby twototwenty » August 30th, 2012, 5:26 pm

Hmm, I was wondering about the same problem myself...as of now, I've jut been testing outside, which has yet to become problematic, but then again, I have yet to begin serious full launches of my glider. Hopefully I will be able to coerce my coach to get us access to my school's 2nd less-used gym.
At least for this event ceiling clutter isn't too much of an issue; you can just keep your launches at a safe height during testing.
Last edited by twototwenty on August 30th, 2012, 5:40 pm, edited 1 time in total.

User avatar
fozendog
Member
Member
Posts: 193
Joined: April 17th, 2012, 5:51 pm
Division: Grad
State: WA
Location: Camas

Re: Elastic Launched Glider C

Postby fozendog » August 30th, 2012, 5:33 pm

Retired1, same with our school. Athletics are highly favored as well. The problem I have found when launching is the air conditioning being a problem.
Stanford '19
Camas Science Olympiad Alumnus
Events: Protein Modeling, Cell Biology, Disease Detectives, Experimental Design, Dynamic Planet, Water Quality

retired1
Member
Member
Posts: 671
Joined: July 25th, 2012, 5:04 pm
Division: Grad
State: FL

Re: Elastic Launched Glider C

Postby retired1 » September 1st, 2012, 12:03 pm

Very true if they will not let you turn up the thermostat a couple of degrees. It will put a premium on proper selection of the aim point as it could be disastrous at the point where climb goes to glide. Still, not as bad as it was for wright stuff or helicopters.

fanjiatian
Member
Member
Posts: 243
Joined: March 16th, 2010, 6:46 pm
Division: Grad
State: -

Re: Elastic Launched Glider C

Postby fanjiatian » September 1st, 2012, 3:31 pm

I read the AMA website and online, but I haven't found much on this topic.

If the lift force is dependent on the area of the glider, density of air and velocity of the glider, what kind of an impact would two different shaped gliders with the same area have on the lift force and velocity?
Forgive me if my jargon is a bit messy, I'm new to flying events in general.

_HenryHscioly_
Member
Member
Posts: 131
Joined: February 5th, 2011, 1:33 pm
Division: C
State: CA

Re: Elastic Launched Glider C

Postby _HenryHscioly_ » September 1st, 2012, 4:22 pm

Different glider parts' shapes increase/decrease drag
With more drag, keeping everything else the same,
velocity will be less, so the lift force will be less and therefore result in a higher sink rate

Not sure what specific parts of the glider you are referring to, but other changes in the glider parts' shapes and positions, such as airfoil shape, incidence,tail moment, dihedral, will also affect the flight
Last edited by _HenryHscioly_ on September 1st, 2012, 4:30 pm, edited 1 time in total.

twototwenty
Exalted Member
Exalted Member
Posts: 292
Joined: March 24th, 2011, 10:28 am
Division: Grad
State: NY

Re: Elastic Launched Glider C

Postby twototwenty » September 1st, 2012, 4:30 pm

Actually, the one factor you're missing is the friction of the glider in the air...different shapes will have different frictions. The page on the AMA website about freeflight trimming , which it seems life you found, talks a lot about this...just read it multiple times and take a little time to think about it, and it will give you a good basic understanding about how the glider flies in the air.

Edit:Looks like HeneryH beat me to it...What he and I said is correct.

_HenryHscioly_
Member
Member
Posts: 131
Joined: February 5th, 2011, 1:33 pm
Division: C
State: CA

Re: Elastic Launched Glider C

Postby _HenryHscioly_ » September 1st, 2012, 4:42 pm

Sweepback on the wing moves the center of lift further back..but if I wanted to do that, I could just move the entire wing further aft.
What are other purposes of a swept wing?
I read somewhere that a swept horizontal stabilizer will prevent flutter, what does that mean?

twototwenty
Exalted Member
Exalted Member
Posts: 292
Joined: March 24th, 2011, 10:28 am
Division: Grad
State: NY

Re: Elastic Launched Glider C

Postby twototwenty » September 1st, 2012, 6:08 pm

_HenryHscioly_ wrote:Sweepback on the wing moves the center of lift further back..but if I wanted to do that, I could just move the entire wing further aft.
What are other purposes of a swept wing?
I read somewhere that a swept horizontal stabilizer will prevent flutter, what does that mean?


By sweepback wings/stab I am presuming you mean wings/stabs that are like this:
-<-
as opposed to this:
-|-
(the hyphens representing the fuselage)
I do not know of other benefits of them, but as far as decreasing flutter, I believe that simply means increasing flight stability, i.e. causing the glider to roll less in the air.

jander14indoor
Member
Member
Posts: 1536
Joined: April 30th, 2007, 7:54 am
State: -

Re: Elastic Launched Glider C

Postby jander14indoor » September 1st, 2012, 7:36 pm

Sweepback (like most jet airliners, and not dihedral) is mostly relevant for very high speed flight.

Flutter comes in on high speed flight/flimsy wings. The tips start oscillating up and down as the vortices shed off. Swept back (vs straight or swept forward) tends to damp out flutter.

Sweepback MIGHT be useful on launch, not much for the glide.

fanjiatian wrote:I read the AMA website and online, but I haven't found much on this topic.

If the lift force is dependent on the area of the glider, density of air and velocity of the glider, what kind of an impact would two different shaped gliders with the same area have on the lift force and velocity?
Forgive me if my jargon is a bit messy, I'm new to flying events in general.


Not clear what kind of shape you are asking about.
- If cross section of wing (airfoil) changing that will change the lift and drag coefficients that goes into that equation.
- If wing planform (outline from top) that mainly affects drag, but lift a little too.
- If fuse shape, mainly drag.
- If you are talking about stab shapes, that's a big, it depends, but for most cases it affects drag most.

Jeff Anderson
Livonia, MI

dandaman
Member
Member
Posts: 13
Joined: December 30th, 2011, 7:59 am
Division: C
State: IA

Re: Elastic Launched Glider C

Postby dandaman » September 10th, 2012, 8:06 am

I've made a lot of balsa planes in my day, and I am sooo glad that we don't hafta do the helicopter again, I think I'll basically be a one man team o the building... with maybe 2 people to help, which'll be a blast! :? Ive found from my own designs that wide wings tend to glide much better, wheres they fly slower and dont go as well with propelled flight.

swade
Member
Member
Posts: 11
Joined: September 21st, 2012, 2:10 pm
Division: C
State: NV

Fun!

Postby swade » September 21st, 2012, 2:37 pm

This event looks like a great deal of fun! I think that it's best to make a design with the world's slowest stall speed and increase the size of the wings until it flys at such a speed. :idea: Basically as big a wing as possible while maintaining stable flight. What do you think?

retired1
Member
Member
Posts: 671
Joined: July 25th, 2012, 5:04 pm
Division: Grad
State: FL

Re: Elastic Launched Glider C

Postby retired1 » September 21st, 2012, 2:59 pm

Weight is one of the most important factors. The more it weighs, the faster it will come down, all else equal.


Return to “2013 Build Events”

Who is online

Users browsing this forum: No registered users and 0 guests