Simviation Forum - Throttle synchronization

Jan 14^th, 2010 at 9:24am

snippyfsxer Offline
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My Saitek throttle quadrants seem to be wearing out and I have to recalibrate them yet again. Even when perfectly synchronized, if I'm flying a 3 or 4 engine craft, it is difficult to get them all at the same power levels. The tedious process of calibration always brings up the same questions, so I might as well ask:

In the old days, like piston propliners and earlier jets like the 707, how did it work? Did the pilot set the power and then the flight engineer came in and tweaked them on takeoff or landing? I saw one of the Airport movies and, If I remember correctly, the FE had his hands on top of the pilots, is this why? Or was it so he could feel any funny engine vibrations translated through the throttle levers? I imagine that those throttles must have gotten out of calibration rather easily.

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Reply #1 - Jan 14^th, 2010 at 10:19am

DaveSims Offline
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In a real multi engine aircraft, the throttles are often out of sync, mainly because of differences between the two engines. No two engines, even brand new, perform exactly the same. One might have an ounce or two more power, might respond a little differently. As the airplane ages, one engine may wear differently or even be replaced sooner leaving different aged engines on a single aircraft. Usually the differences are minute, but in cruise it is common to tweak one throttle or one prop lever to try to balance the engines.

Dave

www.flymcw.com

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Reply #2 - Jan 14^th, 2010 at 10:29am

C Offline
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snippyfsxer wrote on Jan 14^th, 2010 at 9:24am:

In the old days, like piston propliners and earlier jets like the 707, how did it work? Did the pilot set the power and then the flight engineer came in and tweaked them on takeoff or landing? I saw one of the Airport movies and, If I remember correctly, the FE had his hands on top of the pilots, is this why? Or was it so he could feel any funny engine vibrations translated through the throttle levers? I imagine that those throttles must have gotten out of calibration rather easily.

The engineer may well have had his hand there to ensure that the pilots didn't do anything they shouldn't, such as surge an engine, as he can keep his eyes 90-100% on the instruments, which they can't. Some aircraft (VC10 included) by having a separate set of throttles for the engineer. That way it's easier for him to set and monitor powers, and tweak the throttle settings to keep the engines synched in flight.

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Reply #3 - Jan 14^th, 2010 at 10:40am

Fozzer Offline
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Talking about synchronising the Throttles...

I always notice on my Default Beech Baron 58, that even with the Sync Toggle Switch on, the twin engines sound as though they are hunting, slightly out of sync with each other during the cruise.

(Both the Throttles are set to move together, under the control of the Joystick Throttle Lever)

Would slightly maladjusted manual Prop Control Levers aggravate the problem?

Is the Sim programmed to allow the engine Sync Switch to work as intended?

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Reply #4 - Jan 14^th, 2010 at 3:21pm

C Offline
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Fozzer wrote on Jan 14^th, 2010 at 10:40am:

I always notice on my Default Beech Baron 58, that even with the Sync Toggle Switch on, the twin engines sound as though they are hunting, slightly out of sync with each other during the cruise.

They obviously recorded the sound in a unsynched aircraft! Grin

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Reply #5 - Jan 14^th, 2010 at 7:29pm

BSW727 Offline
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The pilots set the power for takeoff and the engineer would reach forward and tweak the throttle for precise power before 80 KIAS in the 727.

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Reply #6 - Jan 14^th, 2010 at 9:28pm

olderndirt Offline
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This seems to cover the original question.
http://en.wikipedia.org/wiki/propeller_synchronization

THIS IS NOT A PANAM CLIPPER

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Reply #7 - Jan 14^th, 2010 at 11:39pm

snippyfsxer Offline
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olderndirt wrote on Jan 14^th, 2010 at 9:28pm:

This seems to cover the original question.
http://en.wikipedia.org/wiki/propeller_synchronization

Wow, there is a Wikipedia article for everything these days!

Sorry for the vagueness of the question. Actually I wasn't talking about prop sync, but power/throttle lever "sync", and I think BSW727 clarified it. Depending on where the throttles are mounted (like on your desktop) combined with the shape of your hand, can lead to the #3 under your ring finger falling behind, the #4 under the pinky, slightly forward of the rest, and 1 and 2 just about right. (I know, I know, I've got problems, don't I

) And that is even when the levers are perfectly calibrated.

I sometimes have a tendency to pull off to one side, espcially during the landing flare, as a result. I imagine even if the throttles are digital, if you are controlling them manually, you still have this problem related to the way your hand sits on the quadrant. I figured the FE must have done something beside just sitting there watching a bunch of guages!

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Reply #8 - Jan 15^th, 2010 at 4:30am

Fozzer Offline
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An elderly FS 2004 addict!
Hereford. England. EGBS.

Posts: 24861

..I've just remembered that the Default Beechcraft King Air 350 Turboprop is fitted with a Synchroniser Push button and Indicator (a revolving propeller) on the instrument Panel.

Once both propellers, Throttle and Prop RPM, are fully synchronised by adjusting the Levers, the propeller indicator stops revolving, and the button is then engaged, both engines are then in Sync with each other.

Note the recommendation for take-off and landing...>>>

http://en.wikipedia.org/wiki/Propeller_synchronization ...thanks Older'n!

I must fit the two devices, (Button and Indicator), in my Beechcraft Piston Prop Twins to prevent the annoying engine "hunting" during the cruise!...

...!

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Reply #9 - Jan 15^th, 2010 at 4:41am

Hagar Offline
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Fozzer wrote on Jan 15^th, 2010 at 4:30am:

I must fit the two devices, (Button and Indicator), in my Beechcraft Piston Prop Twins to prevent the annoying engine "hunting" during the cruise!...

...!

I'm not convinced that FS is quite that realistic Paul. Undecided

C is probably right about the sound. C wrote on Jan 14^th, 2010 at 3:21pm:

They obviously recorded the sound in a unsynched aircraft! Grin

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Reply #10 - Jan 15^th, 2010 at 5:14am

Fozzer Offline
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Hagar wrote on Jan 15^th, 2010 at 4:41am:

Fozzer wrote on Jan 15^th, 2010 at 4:30am:

I must fit the two devices, (Button and Indicator), in my Beechcraft Piston Prop Twins to prevent the annoying engine "hunting" during the cruise!...

...!

I'm not convinced that FS is quite that realistic Paul. Undecided

C is probably right about the sound. C wrote on Jan 14^th, 2010 at 3:21pm:

They obviously recorded the sound in a unsynched aircraft! Grin

I've just given it a try, and it certainly works with the Turboprop Twins.
The engines sound out-of balance until all the levers are correctly set, then when the Indicator stops revolving and the Sync Button is pressed, both engines operate in perfect Sync with each other in the cruise...

...!
Any further change in the lever positions and the engines require re-synchronising again.
It seem to work OK in the Turboprop, with its Turbine+Prop Engines...
Whether it is as effective in the Piston Prop Twins I have yet to discover, with their default Sound recording... Roll Eyes

...!

...further experimentation required... Wink

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Paul...G-BPLF...FS 2004...

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...Hunting has been banned in England!.... Wink

...!

.... Grin

....!

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Reply #11 - Jan 15^th, 2010 at 11:14pm

beaky Offline
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Hagar wrote on Jan 15^th, 2010 at 4:41am:

Fozzer wrote on Jan 15^th, 2010 at 4:30am:

I must fit the two devices, (Button and Indicator), in my Beechcraft Piston Prop Twins to prevent the annoying engine "hunting" during the cruise!...

...!

I'm not convinced that FS is quite that realistic Paul. Undecided

C is probably right about the sound. C wrote on Jan 14^th, 2010 at 3:21pm:

They obviously recorded the sound in a unsynched aircraft! Grin

I know that some multi-engine twin models use a single engine sound file, and it is duplicated based on the number of engines specified. So, while FS is not perfectly realistic in this regard, it does simulate out-of-sync pretty well. Just take a twin up some time and pull the throttle back on one engine ; you will see what I mean.
I think the amount of realism depends on the number of sound files for different power settings, and how smoothly they can be blended together.

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