Aaq, the medrash says that shlomo hamelech created essentially a car, but hid it when he saw that the reshoim would use it for evil. He also had a sefer of refuos, chazal sau, with the cure for every disease, but it was hidden awa, so that people need to daven.
Chazal knew the interworkings of creation not only on a physical level, but on a deeper one as well.
Your question can be asked of lots of other things chazal were capable of – the arizal says that the smallest of the amoraim was capable of techias hamaysim, so why didn’t the chachamim just revive everyone who died everyday? The answer is they knew not to disrupt Hashem’s plans. The chovos halevavos writes that every invention and discovery in the non jewish world has its time and place. For chazal to interfere with that would have been catastrophic.
And yes, making a statement that chazal were missing in their knowledge of the physical world is heresy according to the vast majority of rishonim and achronim.