The Planes That Can Fly Themselves: Passive Stability

Hello and welcome back to The Fundamentals! I am discussing glider design in the context of a class competition.
Sorry about the bad audio... again. Last time there was a buzzing that I had to remove with heavy noise reduction. Now that I've fixed the buzzing I accidentally unplugged my mic at the start of the video so I just recorded my voice from inside my pocket. I tried to combine this audio with the (very noisey) camera audio to get something passable. I think this series is cursed.
Music:
1. Lone Wolf - Dan Lebowitz (0:13)
2. Egmont Overture Finale - Kevin MacLeod (7:54)
Egmont Overture Finale by Kevin MacLeod is licensed under a Creative Commons Attribution license (creativecommons.org/licenses/...)
Source: incompetech.com/music/royalty-...
Artist: incompetech.com/
Most of the music I use is from the RUclips Audio Library.

[@petersmythe6462]

One thing to consider with dihedral is what happens with a small sideslip angle.
The lift on the forward wing increases, which induces roll in the other direction to the sideslip.
So you get
small sideslip -> counter roll -> lift vector changes -> no more sideslip.
With the opposite situation, anhedral, a small sideslip induces a sympathetic roll, which in a plane with a vertical stabilizer will induce more sideslip and roll and turn the sideslip into prograde velocity component and more sideslip and more roll until the thing falls over.

[@AmbiguousAdventurer]

For a airplane to be glide stable, you have to have certain parameters tune. Basically you want a negative feedback loop, when the wing starts to stall, you want the aircraft to pitch down, and when it speeds up, you want it to pitch up. To achieve that one way is to make it a slight sweep wing design, and make the wing root's angle of attack (AOA) higher than wing tips. When the plane pitches up, wing root will stall and move the center of lift aft, this will make the plane pitch forward therefore make it a stable flight.

[@petersmythe6462]

Note that cambered wings retreat the CoL back from the quarter chord significantly. With sufficient camber it is possible to have it be behind the half chord.

[@raulcavalcante9193]

this is certainly the most underrated channel on youtube

[@ConHathy]

Near the end of the video, I mention that our performance was poor because we were heavy. This is not necessarily because weight alone changes your range (range is just a function of your lift/drag ratio and the starting height). The reason we had problems was that heavier planes need to fly faster to achieve the max L/D ratio and we could not throw the plane fast enough. This lead to the plane diving "to gain speed" which obviously isn't great for the range. We could reduce the weight to fix this or increase the wing size to decrease our overall wing loading. This is why you can have a full-size glider that is much heavier than our scale ones, but with a similar glide ratio: distance only depends on aerodynamics so long as you can fly fast enough.

[@PaulTheSkeptic]

I used to love to make paper airplanes as a kid and when I'd throw it off a high place, I'd notice that a regular plane could go anywhere. It could decide to go straight down or curve around. Or every once in a while it would sail gently off into the distance but this was pretty rare. So then I decided to bend the paper in the rear up, mimicking pulling back on the stick the whole time.. This produced a more predictable but strange flight pattern. It would sail off and sort of stall, then it would nose dive but quickly recover coming back up, over and over. I wonder if that might not be an option for you.
If you're going for distance, obviously you want that nice sailing of into the distance thing. But, if you're going for consistent distance over many tries, then that approach might work. But you looked like you just wanted to hit that tarp. In that case, you might be able to fine tune the rear... whatever it's called. Allerons? You know what I mean. The tail piece. Playing with different angles might produce a more consistent result.

[@tapasnaik6092]

you have great understanding about the topic , you should make a team and participate in compition like REDBULL FLUGTAG

[@petersmythe6462]

My impression is that elliptical wings are kinda overkill. You can get almost the same spanwise efficiency from a trapezoidal wing.

[@yes8163]

A small suggestion. Please make a video on astronomy and using starcharts and observing celestial bodies.

[@yes8163]

Just found your channel!Love it!I too tried to make one myself,but it broke into pieces as I did not have the materials to make one properly.Wish me good luck in making another please.

[@ConHathy]

Keep trying, flight is always super rewarding

[@gulshanchaurasia2233]

dragonflies have elliptical wings

[@mohitkhandate1247]

What materials could be used for the Gliders???Also great vid btw

[@ConHathy]

We were allowed to use anything as long as we didn't spend too much money, but we were provided some basics like foam board and balsa wood

[@eskecitothesqueakual1042]

Found you from reddit