ει', ἐά_ν, on the chance that.—εἰ or ἐά_ν may set forth the motive for the action or feeling expressed by the apodosis, and with the force of on the chance that, in case that, in the hope that, if haply.
After primary tenses in the apodosis, we have εἰ with the indicative or ἐά_ν (πως) with the subjunctive; after secondary tenses, εἰ with the optative or, occasionally, ἐά_ν (πως) with the subjunctive. Homer has sometimes the optative after primary tenses. The reference is to the future as in final clauses.
The protasis here depends, not on the apodosis proper, but on the idea of purpose or desire suggested by the thought. The accomplishment of the purpose may be desired or not desired, and by the subject either of the apodosis or of the protasis.
νῦν αὖτ' ἐγχείῃ πειρήσομαι, αἴ κε τύχωμι
πορευόμενοι ἐς τὴν Ἀσία_ν ὡς βασιλέα_, εἴ πως πείσειαν αὐτόν
N.—This use is to be distinguished from that of εἰ ἄρα
a. This construction should be distinguished from cases like
ἐπιβουλεύουσιν . . . ἐξελθεῖν . . ., ἢν δύνωνται βιάσασθαι
b. Homer uses this construction as an object clause in dependence on οἶδα, εἶδον, or on a
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].