View Full Version : Prop sychronisers... on the Nimrod???
Shaggy Sheep Driver
9th Nov 2012, 23:53
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!
RandomBlah
10th Nov 2012, 01:01
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!
Adam Nams
10th Nov 2012, 02:16
whining type noise that occurred when the engines were not in sync
Otherwise known as "The AEO" :E
Hat, coat rations...
NutLoose
10th Nov 2012, 06:41
As fitted to the VC10 as well.
fergineer
10th Nov 2012, 08:21
The secrte is out... To all those co's sorry!!!!!!
Shaggy Sheep Driver
10th Nov 2012, 16:23
Ta for that. I'd no idea one had to synchronise jet engines! Or maybe only dH thought one had to. :E
ExAscoteer
10th Nov 2012, 16:27
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!
Onceapilot
10th Nov 2012, 20:46
Can't be the just the AEO, that whining noise seems to occur in many aircraft?
OAP
Dengue_Dude
10th Nov 2012, 20:54
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.
Ho ho, you could tell which staff navs were unpopular. You'd just give on throttle a little tweak to de-synch the donks . . .
More than one way to skin a cat as the saying goes :D
fergineer
10th Nov 2012, 21:50
Was that inbetween getting the tuning right on the ADF DD
kevnurse
14th Nov 2012, 22:01
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.
Duncan D'Sorderlee
15th Nov 2012, 10:27
As stated, it did give the co something to do on that long transit from ISK to the Malin!
Duncs:ok:
Neptunus Rex
15th Nov 2012, 17:29
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.