Goose beat me to it. The composition of the coins, like the first IHC's have more nickel in them, so perhaps the designation isn't used. Don't know for sure though.
The metal composition is the reason. You won't see it on IHC's minted from 1859 thru 1863 either and some of the 1864's until they changed the metal mixture later in the minting process.
The composition of Flying Eagle Cents is .880 copper, .120 nickel, as compared to that of .950 copper, . 050 tin and zinc.
While that might not sound like a big difference in the alloy, the Flying Eagle Cents did not begin life as flaming/full red "RD" coins like the Indian Cents did and thus, are not designated "RD", "RB" or "BN".
I don't think I've ever seen a red Flying Eagle. The nickel in the alloy is what I believe creates this. Likewise, I wonder why they still use RD on Lincoln cents that are being minted now? Shouldn't they be designated PNK for Pink?
Comments
I don't think that the others do because they look more like a "nickelish" color.
. 050 tin and zinc.
While that might not sound like a big difference in the alloy, the Flying Eagle Cents did not begin life as flaming/full red "RD" coins like the Indian Cents did and thus, are not designated "RD", "RB" or "BN".