Anyone know why Arnold Rapido ignored TT and went with the more challenging (smaller) N scale? Did TT come out before or after N?
“Too Tiny” - interesting how times change.
TT was introduced shortly after WWII in the mid-late 40’s long before N scale and had about 20 years to develop before N took over. TT never moved much after the initial excitement over the new scale died out and by the mid 50’s was sort of dead in the water with only a very few US suppliers.
To my way of thinking, I never saw a creditable TT scale U.S. production steamer though there were a very few in production. Slowly, the limited manufacturing pool of this special, smaller scale died out due to lack of interest as well as highly detailed and functional HO locos and rolling stock in huge abundance constantly entering the market.
HO Scale detail came up fast in the 50’s and by the early 60’s. The O scale goliath was mortally wounded as HO was the number one scale in the U.S. A position it still holds today and with good reason, too.
N scale was just what the doctor ordered and technology was ready to move with it as well when it was introduced. The modern, mobile, 60’s family with limited space looked on HO as being just a tad too big for a new generation of young MR’s in cramped apartments and frequent, on-the-go, movers.
TT became a mystery to many newbies in MR and only we old timers remember much about it.
TT scale did not die. It still exists. The TT scale community is maybe rather small, but there are people worldwide who like North American TT scale. The number of North American RTR models in TT is rather limited, but there are some: SW1200 switcher, ARA 1937 40’ boxcars, Fowlers… and dozens of kits.
A good place to start with TT scale would be the board of its community: www.ttnut.com
If you find N scale too small and H0 scale too big, TT is the way to go, especially if you are not afraid of kitbashing 
Everyone will be very welcome. The more people get involved in it, the more variety it adds to the scale and makes the future RTR projects possible - and who knows, maybe TT even returns back to the pages of MR some day?
Several of the posts here may need some correction: TT scale is an American invention. 1ft equals 1/10 inch. This was an advantage in 1950s. People just took the size of the prototype in feet, divided by 10 and got the size in TT in inches! Can it be easier that that?
My area of interest is Pennsylvania Railroad, in TT-scale (of course).
OO scale, TT scale, Q scale, Standard… Lots of scales have been tried here. I personally find HO to be too small, but that’s just me. I really am amazed when I see the work of those who build in these scales, ones that were often ahead of their times.