Elastic Launched Glider C

[twototwenty]

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]

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.

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]

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]

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. Basically as big a wing as possible while maintaining stable flight. What do you think?

[retired1]

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

[himlynx]

I have read the old rules to which a link was given in the Helicopter - Future Aviation Events forum. I gather that the length and wingspan are both limited to 30 cm. Further, in the AMA website there was a reference to the wing chord being limited to 3 inches. Now I have two questions for the rule makers:
1. Are biplanes and triplanes allowed ?
2. Will Science Olympiad have a limit of 3 inches for the chord ?

[retired1]

this year's rules limit the wingspan to 30 cm. There is no fuselage or chord limit. There is a 10g max wt and the nose has to be larger than 13.7 mm. Lots more rules.
My thought is that a multi wing model would not survive the launch. Also it will weigh a lot more and weight is a killer for this event.

[piisamazing]

Another important thing to keep in mind with weight is it needs to be heavy enough to stabilize itself so it can enter into a consistent glide pattern, so making the lightest possible glider does not necessarily mean it will fly longer.

[retired1]

It has to be strong enough to withstand the 0 to 100++ of the launch. With a 35' ceiling for state, I rather doubt if most people can build one too light and still have it fly.

[_HenryHscioly_]

I believe that I read somewhere that said if the nose moment was too long and not enough mass, the glider wont transition properly. Is that what you are talking about, piisamazing?

I cant find where I read that from.. and I still havent flown a glider in a gym yet nor have i gotten any of my gliders to transition from an upward toss in my living room

I dont understand why too long of a nose moment would affect transition, as long as the cg was correct >.<