The "Barton Werper" series of unauthorized Tarzan books had, at one point, a negative reputation among Edgar Rice Burroughs fans. They were considered inferior to Burroughs' original Tarzan novels. That's why I never, in all these decades of being an ERB fan, tried finding any of the Werper books. Last year, I found two of the books at a used bookstore. They were the first one, "Tarzan and the Silver Globe" and the book I'm reviewing, the fifth volume, "Tarzan and the Winged Invaders". I read the first one last year.
And "Winged Invaders" is an improvement over "Silver Globes". Which isn't saying much. H pseudonymous books only seem to know some of the lore laid out by Burroughs, yet they get so much of the lore wrong. At one point, Jane, Tarzan's wife, is described as having the black hair. In the original Tarzan novels, she was blond. The mangani word "but", which translates to "rhinoceros" in English is said to belong to the natives of Africa - humans. No, it's a mangani term. But then, so many others seem to be able to speak mangani aside from Tarzan. Jane, Gonna, a member of the Waziri tribe, etc. Tarzan knows the language because he was raised as a mangani. The others weren't. The writing and story is much better in this the fifth unauthorized Tarzan novel is an improvement over the first book. Which isn't really saying much. It's still subpar.
Overall, this is a mediocre, bland book. Even if you're a Tarzan fan, or Edgar Rice Burroughs fan, there's no reason to waste time on "Tarzan and the Winged Invaders" or "Tarzan and the Silver Globe".
The final volume of this unauthorized rip-off series issued in the 60s, this one - as usual - features dull monsters being commanded by a gorgeous vampire queen. More of the same as the previous four books, though this might be the best of them. They're all so dreadful, though, that it's hard to be certain.