This is Dropshot:
No toy of Dropshot was ever released, but his prototype was apparently created at around the same time as the other Generation 1 Triple Changers (late 1985-ish), and was somewhat smaller — probably about 10cm tall, as opposed to 15-ish.
The character’s likeness made its way into Transformers Armada and Transformers: Energon comics as a spear-carrier. He dies.
Anyway, why am I talking about this obscure unreleased Transformer? Because he reminds me of this classic piece of internet history:
Dropshot is indeed a horse that turns into a plane.