I'll try and re post it as close to what i wrote.
The Royal engines were not made by Thunder Tiger but by Leo engines which is owned by either a son or relative of Ai Ling the owner of T.T. their offerings also paralleled the OS line very closely and probably were mistaken for OS more then once.
As to the Magnum that was a trade name owned by Hobby Shack(People) and they were made by Thunder Tiger. They did not sell their engines in this country at that time I guess because of contractual obligations. Hobby shack and Thunder Tiger parted and went on their own way with HS retaining control of their engine trade name Magnum. Thunder Tiger then started selling their engines in this country under their own trade name. Magnum is to the best of my knowledge still sold only by Hobby People.
Dennis
The Royal engines used many parts that were the exact same part as the TT made Magnums, because they were made by Thunder Tiger.
I sold both lines in the late 80s early 90s, They were brought into the US by Global Hobby, and I was a U.S. Dealer for both of them. It maybe that Ai Ling's relative bought his parts from TT, however they were many of the exact same parts.
I still have many parts and even a few NEW Royal engines and TT made Magnum engine and parts on the shelf, many are identical with identical marks on them.
The reason Thunder Tiger could not, or did not sale Thunder Tiger engines in the US was because of a contract they had with GLOBAL not to. It made sense untill it came apart and GLOBAL switched, or had to switch, the manufacturer of their line of Magnum Engines to China.
And YES as I stated earlier in the thread, they were very much OS Clones, you could even use the parts of either Royal or Magnum in the OS FSR engines.
And Magnum was NOT only sold by Hobby People, I (AERO PRODUCTS)sold them, many 100s of them, as I have for the past 3 decades, both TT made and Chinese made versions.
Randy