How do tailless SWIFT gliders maintain longitudinal stability without tails?

[Frenemy90210]

< Mentor Note -- Poster has been reminded to post links in future thread starts to help others understand the question being asked >

Since SWIFT gliders do not have tails, what stops them from going into forward/backward spin ?

 

[berkeman]

Link?

 

[Frenemy90210]

Link?

Dont have any link. It was my guess that glider has more chances to go into forward spin being tail less. I am a newbie in aeronautics.

 

[berkeman]

Dont have any link. It was my guess that glider has more chances to go into forward spin being tail less. I am a newbie in aeronautics.

What's a SWIFT glider? You don't have any links to what that is?

 

[rootone]

I'd say it's referring to this:
https://en.wikipedia.org/wiki/Aériane_Swift
In which case the role of a vertical stabilizer at the tail is replaced by winglets on the main wing.

 

[berkeman]

I'd say it's referring to this:
https://en.wikipedia.org/wiki/Aériane_Swift
In which case the role of a vertical stabilizer at the tail is replaced by winglets on the main wing.

Like this?

http://www.jet-scout.com/pictures_big/260_pic1.jpg

 

[rootone]

That would be it, and I stumbled across a forum for owners of this aircraft.
Possibly could be of some use if the OP wants finer details about it.
http://swiftpilots.freeforums.net/board/2/swift-ultralight-glider

 

[Frenemy90210]

Like this?

http://www.jet-scout.com/pictures_big/260_pic1.jpg
View attachment 211946

Yes; Thats right. Sorry earlier I misunderstood your question.

Edit : I thought you were asking for a link which says that SWIFT gliders have tendencies to go into forward spin; I did not realize that you were asking for link to the SWIFT glider itself.

Thanks.

 

[Frenemy90210]

I'd say it's referring to this:
https://en.wikipedia.org/wiki/Aériane_Swift
In which case the role of a vertical stabilizer at the tail is replaced by winglets on the main wing.

I think winglets resist the "yaw" not the pitch; ( Feel free to correct.) My question was about "pitch" kind of motion.

https://www.google.co.in/search?q=Yaw&oq=Yaw&aqs=chrome..69i57j0l5.2947j0j7&sourceid=chrome&ie=UTF-8

 

[donpacino]

http://www.newfoxy.com/wp-content/uploads/2016/06/Control-Surfaces.jpg

If you look at your standard aircraft there are a lot of redundancy points. Technically the spoilers, the flaps, and elevators, and the ailerons will all effect pitch. During normal operation the elevators act as your primary pitch control while your ailerons act as roll control. But there are many stories of multiple control surfaces being damaged or destroyed and pilots still flying home. WHY? because the control surfaces are redundant.

With the glider you posted, there is only 1 wing, with however many control surfaces on said wing (I'm not sure if they just have ailerons, or spoilers and ailerons. The ailerons on the swift glider can still control pitch if they move up and down at the same time, it is only when they counteract each other (one up, one down) that roll occurs. To control pitch on a swift glider, one just needs to move the ailerons up and down together.

 

[CWatters]

Since SWIFT gliders do not have tails, what stops them from going into forward/backward spin ?

There are two main ways of providing longitudinal stability on a tailless aircraft...

1) Straight winged aircraft use special wing sections that have a reflex camber (sweep up) at the trailing edge. This and a forward center of gravity provide the necessary longitudinal stability. Example wing section for tailless aircraft:

2) Swept wing aircraft typically use wings that are twisted so the wing root and tips are at different angles of attack. Usually the wing tips are at a more negative angle of attack than the wing root. The twist can either be an actual twist or an aerodynamic twist or a combination of both. (Note: This should not be confused with washout which is to aid lateral stability close to the stall).

There is a good explanation of the issue here by someone who has designed wing sections for tailless aircraft..
https://www.mh-aerotools.de/airfoils/flywing1.htm