return asyncChain(10, 'SECOND CHAIN');
}).then(function(){
  return asyncChain(10, 'THIRD CHAIN');
});

Ans2: var tasks = [fn1, fn2, fn3...];

tasks.reduce(function(cur, next) {
    return cur.then(next);
}, RSVP.resolve()).then(function() {
    //all executed
});

Or values:
var idsToDelete = [1,2,3];

idsToDelete.reduce(function(cur, next) {
    return cur.then(function() {
        return http.post("/delete.php?id=" + next);
    });
}, RSVP.resolve()).then(function() {
    //all executed
});