Actually Jetfire was a repackaged Takara Valkrye... and even a few of the produced pieces even has "UN SPACY" and the 'Robotech' symbol as stickers on them. I even saw one that had the Skull Squadron logo on the cockpit shield.
All in All, it was a copy of the Japanese 1:55 scale Super Valkyrie. Many of Hasbro's first line of Transformers were copies of Japanese toys from various anime series and toy companies, including the Super Valkyrie, renamed to "Jetfire." The existence of this toy in America caused headaches for Matchbox when they were creating their Robotech line of toys, because they could not create their own transforming version of the Veritech. Also found this online:
Why is Jetfire just like a Robotech Veritech fighter?
Technically, it's a Macross Valkyrie, as the Robotech show was a
derivative of three separate Anime series: Macross, Southern Cross, and
Mospeada. Hasbro felt that the Autobots were too short on air power,
and their search for a cool airplane toy came up with Bandai's Valkyrie.
To leave a lot of legal technicalities out, Hasbro and Harmony Gold (who
released Robotech in America), as well as a few other companies (like
FASA, the makers of Battletech) bought the rights to use that "shape" of
robot, and Jetfire was born.
There has been some debate on exactly what model of Valkyrie Jetfire is.
His body and head match the VF-1S, although there was no VF-1S with
Jetfire's coloring in the series. There was a special edition release
of Valkyrie toys to accompany "Macross: The Movie", in which Hikaru
(Rick Hunter) flew a white VF-1S with red and black trim. Although the
colors are Jetfire's, their placement is reversed -- that is, black
where Jetfire has red, and red where he has black. The Super Armor for
movie edition Valkyries was red but their eye strips were green. Also,
Fokker's "skull special" Valkyrie was a VF-1S with black and yellow
paint. Change the yellow to red, and paint the nosecone, and you have
Jetfire. So, although there are a few close cousins, there was never a
Valkyrie that looked /just/ like Jetfire in Macross.
Since he was based on a Macross toy, some Jetfires have a small Macross
symbol (a circle with a double-winged thingy inside) on one wing along
the red stripe. Some toys have this symbol painted on, some have it as
a sticker, and some do not have it at all.