Both maples, October Glory (not Red October) and Red Sunset are relativelyfast growing trees with wide crowns. They will reach 50 feet in height after 20 to 25 years or so with reasonably good growing conditions. Attempting to keep these or really any tree smaller than it's natural inclination through pruning is not a practical strategy. It won't kill the tree, but becomes increasingly time consuming and dangerous as the tree grows. Further, pruning stimulates renewed growth so is really self-defeating unless you are dealing with fruit trees where pruning has a different purpose than size control. If you Google "small growing trees" you will turn up many possibilities, but no tree stops growing at a particular height. In a sense, you are looking for contradictory things: a strong growing tree suitable for a swing in a reasonable number of years plus small stature. The original maple suggestions would certainly give you the first. Unless the perspective in the photo is somewhat skewed, it looks as if there will be plenty of the lake still visible even with one of the maples planted where the pear tree is now.

Viburnum prunifolium, called Black Haw here, is a lovely small tree, if you can find it. It's native to my woods, and I give away many seedlings to friends. In the open, it has a handsome shape and good fall color.

Viburnum prunifolium is a lovely native shrub/tree, but I am having a lot of trouble seeing one as suitable for hanging a swing. I don't believe I have ever seen one more than 10 or 12 feet in height and the branches tend to grow strongly upright rather than in a horizontal plane necessary for a swing.

Most trees never stop growing...a small tree is usually either a slow growing tree or a short lived one. And fast growing trees tend to be weak wooded.

Redbud is the right size but short lived and prone to falling apart...NOT good for a tree swing.

Ironwood is a good idea. Very strong wood, as the name would suggest. Also, since you say you liked fruit trees, there are some pretty tough crabapple varieties.

What USDA zone are you in?

just keep on pruning the
branches to “dwarf” it at under 30 feet and 25 wide?

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will you be buying a cherry picker to do this???

can you give us a better idea of where you are... z6 is rather nebulous.. big city name ... will tell us north or south ...

a nice.. small tree ... in my MI yard is the red flowering buckeye ... see link ... no clue if it would work in your area ....

but it will never be a swing tree ...

and it would be about 20 years.. no matter what you plant.. to get it to swing size ... i suggest a couple [3] of 4 x 6s .... and put in a nice two person swing ... and you can use it this season ... forget about making it a tree thing ...

ken

https://www.google.com/search?q=red+flowering+buckeye&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjLq5j8wZPMAhWmwYMKHWCZBB0Q_AUICCgC&biw=965&bih=745&dpr=0.9#imgrc=mq8VNrMZohyfnM%3A

Thank you everyone for all your inputs. I will look into the other trees that you guys have suggested. I guess I'm reaching for the stars having that combination of contradicting parameters--> strong structure that will grow fast and stay small. I suppose if I took out the tree swing requirement, that would open up a whole lot more choices as there are many rapid growing small trees available (will just have to make that swing some other way).

One of the reasons I like the October Glory (my apologies for calling it Red October - I must have been thinking of the movie..) is it's beautiful autumn color. But I can't have a 50 foot tree on that spot. Among other things, I don't want to take out a big part of my next door neighbors view of the lake as well. Our houses are on top of a slope, so a 50-foot crown will be at about eye level and will directly block the view.

So the search continues, but this time with a more doable set of parameters. I just want a rapid growing tree, under 30 ft. tall that will grace us with a beautiful color during the autumn months. And of course, disease resistant would help too.

By the way, I am in western CT, region (6a).

I'd consider Amelanchier, serviceberry. Typically a smallish, often multi-stemmed native tree with white spring flowers and outstanding fall color. And most tend to have a rather open, airy habit that can be easily seen through so they pose virtually no visual block. My first choice would be the hybrid, Amelanchier x grandiflora 'Autumn Brilliance'.