A common feature in the reports of many British civilians who endured the Luftwaffe's blitz of Great Britian in WW2 is that the enemy aircraft were identifiable by the sound that their unsynchronized engines made. How are aero engines synchronizes and why did the Luftwaffe do this to their machines whereas the RAF seemingly did not ?
german engines Yes, German bomber engines 'throbbed', quite distinct sound. Were at least up to Coventry raid, maybe changed later. I also found 'window', silver foil, whether dropped by RAF testing or Germans I don't know, did not know what it was when I first found it on farm fields.
Luftwaffe engines Thanks, guys, for your feedback, but we still don't know what was actually mechanically done to the engines in order to de-synchronise them, or even know what de-synchonising is.
Re: Luftwaffe engines "Desynchin engines" in the case of the 40's piston engines with propellers just means that you run the engines at a slightly different RPM.
I have seen footage of ww2 german planes, and a scene in the cockpit showed the copilot constantly adjusting one throttle against the other, a slight variation of rev rate. Could this result in the sound described?
Surely flying a 2-engined plane with the engines at different revs would cause all kinds of troubles when it came to actually flying in a straight line...
Getting exact the same RPM on both engines is actually rather hard thing to achieve The RPM difference on the engines is so small that it doesn't need any trim to balance the flight. It's not that they run the engines at a several hundred RPM difference, a couple of RPMs is enough to make the effect.
De-synched engines. I'll go for this, which seems to be entirely feasible and I have seen footage of Luftwaffe bomber pilots constantly making throttle adjustments. Many thanks for your replies, chaps ! BG