Prop sychronisers... on the Nimrod???
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Prop sychronisers... on the Nimrod???
Can any former Nimrod crew advise why the aeroplane has an engine sychronisation instrument (3 little props, just like on a 4-engines prop aeroplane)? It had Speys!
My mate who flew 1-11s (also Spey bypass turbojets) confirms that didn't have it, but his Vanguard did!
My mate who flew 1-11s (also Spey bypass turbojets) confirms that didn't have it, but his Vanguard did!
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The 3 little props helped in synchronising the LP RPM of all the engines. The No 2 engine was the master with the instrument showing if the other engines's LPRPM was faster (prop rotates clockwise) or slower (prop rotates anti-clockwise). The speed of the prop rotation was an indicator of how far away the engine was from having the same LP RPM as the no 2. The reason for this ultimately was to remove an anoint whining type noise that occurred when the engines were not in sync - it was nothing to do with fuel economy etc as I'm sure some posters will claim. The instrument itself was a hangover from de Havilland who used to install it as standard on most of their twin engined aircraft.
Alternatively, it gave the co something to do in the cruise that could be destroyed in an instant by the Flt eng switching on the engine anti-icing!
Alternatively, it gave the co something to do in the cruise that could be destroyed in an instant by the Flt eng switching on the engine anti-icing!
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As fitted to the VC10 as well.
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On the Dominie, if you didn't synch up the engines (by ear) the Navs would complain rather bitterly about the beat frequency generated down the back.
Then again, if you did synch the engines they'd only find something else to whinge about!
Then again, if you did synch the engines they'd only find something else to whinge about!
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On the Dominie, if you didn't synch up the engines (by ear) the Navs would complain rather bitterly about the beat frequency generated down the back.
More than one way to skin a cat as the saying goes
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Normally, turbojets are not synched, but due to their proximity to the fuselage of the Comet and Nimrod (and therefore the crew/pax) it was considered to be a good idea to do so. No other reason.
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Synching
Of course, 'twas only the copilots who needed the "little propellors" to synch those mighty Speys. Most Captains had been educated on the Varsity (two Bristol Hercules Radials) then the Shack (four R-R Griffon V12s) so they could synch four Speys by ear; much easier and much faster.
The Nimrod (Ah! de Havilland!) crews had little patience with pilots who were tone deaf.
The Nimrod (Ah! de Havilland!) crews had little patience with pilots who were tone deaf.
