The first part is the landing gear sound is too loud, you're aware of this though I believe.

The second is that I think, for at least the Hurricane and Spitfire, there shouldn't even be an audible whine. It sounds like electric motors(?) to me, pretty much like my experiences as a passenger in a 737. We'ren't they hydraulic, therefore no electric whine noise?

Mayeb there was a whine, but, I have one source, apologies I can't remember which, but possibly one of "Spitfire Ace - Gordon Olive DFC" or "Hurricane - The Last Witnesses" or Brian Lane's book where a pilot says (and I very losely quote) "then up with the landing gear, the only indication being the two dull thuds as the wheels close in'.

So my request is to consider replacing the whine with two thuds.

(all very good reads if you haven't already)

Funnily enough, if I recall correctly, the landing gear bit is just after they describe lifting off, and that is EXACTLY as it feels to me in CloD.