Prop synch'
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Joined: Mar 2000
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From: Dagobah
Prop synch'
Not sure if this is the right place for this question but I figured you clever test pilots would know the answer.....
I'm curious to know how you synch' the props on an aircraft with say four engines? I've only ever flown twin engine aircraft and don't suppose I'm ever likely to fly anything else with more than two propellors these days.
Cheers
YS
I'm curious to know how you synch' the props on an aircraft with say four engines? I've only ever flown twin engine aircraft and don't suppose I'm ever likely to fly anything else with more than two propellors these days.
Cheers
YS
Joined: Jun 2002
Aviation Qualifications: PPL
Posts: 5,103
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From: east ESSEX
Synch
YSW,back in the days of Flight Engineers,it was done by looking out of the windows at the props, having been set to the appropriate RPM, and lining up the inboard and outboard discs.If there was a residual `strobe` from them, then a little tweak on one rpm lever would adjust the strobe effect to zero.Usually each rpm gauge had a small `synchro-wheel` on it which was also used to synch left/ right sides. Then it would be finely adjusted by the FE to get rid of any particular `residual beat`/drone through the airframe.
Nowadays , the systems are all electronic , using either *2,or*3 engine as a Master engine, and each engine has an electronic actuator on the governor assembly, going thru` a phase and speed sensor unit ( phase unit takes the position of the master blade on each prop). The result is the governor unit on each prop is `nudged` to adjust blade pitch and hence Rpm, until they agree with the Master engine- ie synchronised, then adjusted as necessary to `synchrophase` each prop to reduce residual `beat` or vibration/noise. It really makes a significant difference to noise and crew/pax comfort to have them well set-up....certainly in an Albert !!
Nowadays , the systems are all electronic , using either *2,or*3 engine as a Master engine, and each engine has an electronic actuator on the governor assembly, going thru` a phase and speed sensor unit ( phase unit takes the position of the master blade on each prop). The result is the governor unit on each prop is `nudged` to adjust blade pitch and hence Rpm, until they agree with the Master engine- ie synchronised, then adjusted as necessary to `synchrophase` each prop to reduce residual `beat` or vibration/noise. It really makes a significant difference to noise and crew/pax comfort to have them well set-up....certainly in an Albert !!
Thread Starter
Joined: Mar 2000
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From: Dagobah
Thanks for that. It's something I've always been curious about, probably because it took me forever to get the hang of trying to sync two propellors! Don't suppose many civvies like me will ever fly an aircraft with 4 props these days.
YS
YS
Joined: Mar 2000
Posts: 8,571
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From: Arizona USA
You would have liked the Constellation..
...well, the 1649 anyway.
A great aeroplane.
Prop synch was normally done by the flight engineer, as he (only) had the prop controls at his station.
On the DC6, the pilots were indeed able to do this, and it was all (usually) done by ear...with lots of practise, if the prop syncho was unserviceable, which was quite a lot, in my experience.
Start with number one, and work across, in sequence.
Lots of fun....
A great aeroplane.
Prop synch was normally done by the flight engineer, as he (only) had the prop controls at his station.
On the DC6, the pilots were indeed able to do this, and it was all (usually) done by ear...with lots of practise, if the prop syncho was unserviceable, which was quite a lot, in my experience.
Start with number one, and work across, in sequence.
Lots of fun....
Thread Starter
Joined: Mar 2000
Posts: 631
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From: Dagobah
Thanks for that, seems you guys/girls have all been very lucky to fly in what I like to believe was the 'golden romantic' age of aviation, I'm sure it wasn't always that great though. I guess I shall just have to make do with my model connie that sits on my tv!
YS
YS
Joined: Mar 2000
Posts: 8,571
Likes: 3
From: Arizona USA
Well...it wasn't that great...
...always.
The 1649 had fuel (9800 gallons) for 23+ hours, but oil usually ran out after 19...not good.
Then, with all power assisted flight controls, hydraulic leaks abounded.
Did I mention noisey.........yep, sure was, but sounded great.
I personally was very lucky to have flown all the large Lockheed civil aeroplanes...Constellation, Electra, and the TriStar.
In fact, just did a fully automatic landing with a tri-motor at GQNN last week.
PFM....
It simply does not get any better.
The 1649 had fuel (9800 gallons) for 23+ hours, but oil usually ran out after 19...not good.
Then, with all power assisted flight controls, hydraulic leaks abounded.
Did I mention noisey.........yep, sure was, but sounded great.
I personally was very lucky to have flown all the large Lockheed civil aeroplanes...Constellation, Electra, and the TriStar.
In fact, just did a fully automatic landing with a tri-motor at GQNN last week.
PFM....
It simply does not get any better.
