A-frame angle for swing

Question

I'd like to figure out the smallest angle possible for the kid swing A-frame. I will be using 4x8 beam on top and 4x4 for the legs. I am reading two sources and each has different angles:

This site http://myoutdoorplans.com/playhouse/outdoor-playset-plans/ says 15 degree (each side)

This site has plan with higher swing beam but it uses 30 degree http://www.ana-white.com/2010/06/how-build-swing-set-playhouse

I think using the second option plan is OK for the high (10 feet) but the width is also 10 feet which is too much space. Is there like a requirement for the A-frame angle? Or can I use 15 degree just fine? Given proper support and everything else framing correctly.

Answer 1

With the narrower angle (15), they add cross supports. The wider angle (30) is given with no supports.

Making a stable swing set is no joke. Unless it is part of a larger structure that weighs it down, the legs need to be anchored in concrete. When I was a kid I used flimsy backyard swing sets and could easily rock the whole swing set, frame and all, back and forth. Also, the swing set should be 10 feet from any fence, wall or hard surface (like pavement) if you want to avoid injuries. Some children (like myself) will swing out to the maximum height (about 8 feet) then leap out of the seat and go flying. When I was a kid this was a game we played, the object being to see who could catapult themself the furthest distance.

There is no hard and fast rule about the angle. It depends on the design of the swing set, especially the height, the material and the way it is joined. You can use a narrow angle, but the beams must be correspondingly stronger and better anchored.

Answer 2

The angle is not particularly important. With sufficient ground stability and fastening, you could do it with a zero angle: a beam supported by a pair of posts.

For each configuration with a greater angle, the need for strength in the supports and anchoring decreases. When the angle is 180 degrees, the system is completely stable without any anchors at all. Of course, it it useless as a swing, but the point is that it is plenty strong.

If I were you, I would just build it to be as wide as is practical if space is tight, or about 30° to optimize height vs. the amount of materials needed.