It'll never fly

it will never fly

There's no chance that something will work or be successful. He wants to work from home full time, but it will never fly with the bosses. It's an interesting concept, but it would never fly with ordinary consumers.
See also: fly, never, will
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

It'll never fly.

Fig. It will never work!; It will never be approved! (Refers originally to an evaluation of an unlikely-looking aircraft of some type.) l have read your report and studied your proposal. It'll never fly. Your design for a new electric automobile is interesting, but it'll never fly!
See also: fly, never
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
See also:
References in periodicals archive ?
IT'LL NEVER FLY Wingtip embedded in tailplane elevators
In terms of assembly, you can hack this together for a prototype, but it'll never fly in a production environment.
It'll never fly with that ridiculous name Fort Fadeaways.
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