Authority to Fly
94.01.2 (1) No person shall operate a non-type certificated aircraft unless –
(a) in the case of aircraft classified in the paragraphs (a) to (g) of sub- regulation 24.01.1(2) for such aircraft an Authority to Fly or Proving Flight Authority has been issued in terms of these regulations;
Applicability
24.01.1 (1) This Part applies to –
(a) Amateur-built aircraft
(b) Production-built aircraft
(c) Veteran aircraft
(d) Ex-military aircraft
(e) Any other aircraft not qualifying, or not longer qualifying for the issue of a certificate of airworthiness in terms of Part 21 of these Regulations.
(2) The aircraft referred to in sub-regulation (1) are classified in the follow- ing sub-groups –
(a) Aeroplanes, including microlight aeroplanes
(b) Helicopters
(c) Gyroplanes and gyrogliders
(d) Gliders, including self-launching gliders and touring gliders
(e) Manned captive and manned free balloons
(f) Airships
(g) Unmanned aerial vehicles
So, it is illegal to operate an aircraft in any of the categories above without a valid authority to fly.
We should remind ourselves that all offences of the CAR's are potentially punishable by jail sentences without the option of a fine!

Probably will never happen for a first offence but don't keep doing it and think you will get away.
'Pappa wag vir jou'

I agree with John, it would be unforgivably bad airmanship to even consider it.