minimans : I know from tuning Subaru boxer engines that the headers also contribute a huge difference to the sound with a marked difference between equal and unequal length headers.

If the growl is there irrespective of manifolds, stubs or ejectors and exists throughout the rev range it must to be the firing order as per Beermat #45 giving uneven pulses and harmonics that produce the growl.

While we are pondering the meaning of life and where the growl comes from I thought those that haven’t already seen it might like to watch the whirly bits of a Packard Merlin 266 for 30 secs or so.

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Post by Battle of Britain Memorial Flight (Official).

Is it to do with the Ejector exhausts that the Merlin has? Does the Griffon have the same shape and the same flow rates as the Merlin?

By using Ejector exhausts the equivalent of nearly 70 horsepower was obtained by angling the flow backwards rather than sideways and this increased the level maximum speed of the Spitfire by 10 mph.

Earliest versions of the ejector exhausts featured round outlets and later versions of the system used “fishtail” style outlets which marginally increased thrust as it “squashed” the exhaust gasses. The main bonus being it reduced exhaust glare for night flying.

Volume of air and the speed at which the exhaust gases exit the exhaust stubs would have an impact on the resulting sound made. Think of it like a wind instrument perhaps?

You could also ask at any of the larger Fire Stations as some Fire Rescue Units are equipped with radiation detection devices.

TonyT, there were some strange promotions at that time. His regular pilot stayed a Sgt right through OTU and HCU courses and only became F/Sgt after starting their 1st tour of opps at 101.

How many “Flypasts” make a display? What’s the accepted norm? I have seen some flypasts that were just that. A single run left to right or right to left. Probably what they did at Ludford for the 101 reunion on Sunday. So we got far more than I was expecting.

Moaning Minnie: Perhaps they could have fired some tracer or had an AA battery let rip on them and then had a few bale out just to make it more hype worthy. What about a Bf 110 appearing out of the sun to mingle with them. I would think having 3 Lancs in close proximity to each other would be more than enough to satisfy most people. After all they did exactly what it said on the tin so no surprises there.

Not very open and friendly.The North/South divide still exists? Well in some peoples minds. Whatever next? Home rule for Yorkshire? My father was a Yorkshireman and often ventured South but only after having his shots.

Après surfing the net

Best case just the oil seals went letting oil into the inlet hence the smoke. Worst case the bearings went putting debris into the oil system or the impeller broke up putting debris into the inlet track. Latter less likely as debris going into the top of the engine normally results in instant seizure rather than a controlled shut down. I am more au fait with turbos letting go on rolling roads but essentially the result is the same – expensive and time consuming.