Prop sync and noise in twins

Dudley Henriques writes:

We had a Cessna 337 on our line for charter use at one time. It had a sync
gauge. Strangely enough, whenever I had occasion to fly this bird I always
ended up syncing the props by ear. You could easily feel if one of them was
out even by a small amount of RPM.

Logically the smallest differences would also be the most annoying, since they
would result in such slow variations. And in theory you should be able to
eliminate them by adjusting RPM manually. But since the Baron has a prop sync
switch it occurred to me that perhaps the RPM levers aren't precise enough to
make it easy to sync the props (?).

I'm still not clear on whether or not this switch actually moves the prop
levers or what. If it does, it sounds expensive, since it needs an actuator
or servo in the cockpit or along the linkage. If it doesn't, it means that
some of the engine control positions might not accurately reflect the actual
engine settings and that engine settings might not obey the control movements
if prop sync is operating.

--
Transpose mxsmanic and gmail to reach me by e-mail.

On May 21, 9:50 pm, Mxsmanic wrote:
Dudley Henriques writes:
We had a Cessna 337 on our line for charter use at one time. It had a sync
gauge. Strangely enough, whenever I had occasion to fly this bird I always
ended up syncing the props by ear. You could easily feel if one of them was
out even by a small amount of RPM.

Logically the smallest differences would also be the most annoying, since they
would result in such slow variations. And in theory you should be able to
eliminate them by adjusting RPM manually. But since the Baron has a prop sync
switch it occurred to me that perhaps the RPM levers aren't precise enough to
make it easy to sync the props (?).

I'm still not clear on whether or not this switch actually moves the prop
levers or what. If it does, it sounds expensive, since it needs an actuator
or servo in the cockpit or along the linkage. If it doesn't, it means that
some of the engine control positions might not accurately reflect the actual
engine settings and that engine settings might not obey the control movements
if prop sync is operating.

--
Transpose mxsmanic and gmail to reach me by e-mail.

In the baron I got my multi in, you had to first get the props sync'd
up to within 50 rpm. Then you press the sync button and it fine tunes
the prop governors to get them exact. At least thats how I remember
it, it's been a while. Get a POH, it'll have detailed descriptions of
the system. IIRC Beechcraft POH's are pretty expensive (over $100)

On 2007-05-21, Sylvain wrote:
I don't fly something fancy enough to have an automagic sync thingy; so I
go by ear. It is a bit like tuning a guitar really, but fiddling with the

Probably more like tuning a piano, since you're listening for the beat
frequency (or lack thereof).

--
Yes, the Reply-To email address is valid.
Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de

Mxsmanic wrote:
John Theune writes:

If you type in prop synch multi-engine planes into the google search
window the first hit you will see is this
The AVSIM Forums - Viewing topic #736 - Prop sync
Out of synch propellers will not be as obvious or as annoying in a
simulator as in a real plane. In most aircraft with prop synch, you
first manually ...
forums.avsim.net/dcboard.php?az=show_topic&forum=189&topic_id=736&m ode=full
- 56k - Cached - Similar pages

Go there , read it and you will know all you want to know.

Thanks. I guess people in the AVSIM forums actually answer questions rather
than just point people to Google.

I had you blocked for a long time but took you off recently and see I
made a mistake. Your still as much of a ass as before. Try to do a
just a little bit of work yourself.

"Mxsmanic" wrote

I note that the Baron (and presumably other twins) has a prop sync switch
that
somehow synchronizes the prop speeds on both engines. From recordings
I've
heard of the interior noise of the aircraft, it does sound as though props
that are just slightly out of sync can produce a very irritating
intermittent
noise as they move in and out of phase.

Slightly out isn't as bad as way out IMO. One of our guys likes to fly with
that wow-wow-wow-wow going on for hours and it drives me nuts when I'm the
passenger. It's all I can do to prevent myself from reaching over and
adjusting the props myself.

Also, how does the prop sync work? Does it actually move pitch or
throttle
levers or something?

In our aircraft there are pulse generators that monitor engine rpm and feed
a computer. The computer directly controls the right engine prop governor.
The system only works if the engines are already within 50 rpm of each
other. Even then, the system can take up to a minute to sync the props -
it's much easier and quicker to do it manually. Ours has never worked all
that well and we really don't use it, or need it for that matter.

BDS

Mxsmanic wrote in
:

Dudley Henriques writes:

We had a Cessna 337 on our line for charter use at one time. It had a
sync gauge. Strangely enough, whenever I had occasion to fly this
bird I always ended up syncing the props by ear. You could easily
feel if one of them was out even by a small amount of RPM.

Logically the smallest differences would also be the most annoying,
since they would result in such slow variations

You're an idiot.

Bertie

Mxsmanic wrote in
:

Dudley Henriques writes:

We had a Cessna 337 on our line for charter use at one time. It had a
sync gauge. Strangely enough, whenever I had occasion to fly this
bird I always ended up syncing the props by ear. You could easily
feel if one of them was out even by a small amount of RPM.

Logically the smallest differences would also be the most annoying,
since they would result in such slow variations. And in theory you
should be able to eliminate them by adjusting RPM manually. But since
the Baron has a prop sync switch it occurred to me that perhaps the
RPM levers aren't precise enough to make it easy to sync the props
(?).

I'm still not clear on whether or not this switch actually moves the
prop levers or what.

I know, send me $200 and I'll tell you fjukktard


Bertie

buttman wrote in
oups.com:

On May 21, 9:50 pm, Mxsmanic wrote:
Dudley Henriques writes:
We had a Cessna 337 on our line for charter use at one time. It had
a sync gauge. Strangely enough, whenever I had occasion to fly this
bird I always ended up syncing the props by ear. You could easily
feel if one of them was out even by a small amount of RPM.

Logically the smallest differences would also be the most annoying,
since they would result in such slow variations. And in theory you
should be able to eliminate them by adjusting RPM manually. But
since the Baron has a prop sync switch it occurred to me that perhaps
the RPM levers aren't precise enough to make it easy to sync the
props (?).

I'm still not clear on whether or not this switch actually moves the
prop levers or what. If it does, it sounds expensive, since it needs
an actuator or servo in the cockpit or along the linkage. If it
doesn't, it means that some of the engine control positions might not
accurately reflect the actual engine settings and that engine
settings might not obey the control movements if prop sync is
operating.

--
Transpose mxsmanic and gmail to reach me by e-mail.

In the baron I got my multi in, you had to first get the props sync'd
up to within 50 rpm. Then you press the sync button and it fine tunes
the prop governors to get them exact. At least thats how I remember
it, it's been a while. Get a POH, it'll have detailed descriptions of
the system. IIRC Beechcraft POH's are pretty expensive (over $100)

Wow, the modern CFI, waht a mrvel he is.


Bertie

Mxsmanic wrote in
:

I note that the Baron (and presumably other twins) has a prop sync
switch that somehow synchronizes the prop speeds on both engines.
From recordings I've heard of the interior noise of the aircraft, it
does sound as though props that are just slightly out of sync can
produce a very irritating intermittent noise as they move in and out
of phase.

If you want to simulate that accurately, just talk while your's jerking off
with your sim

Berti e

Mxsmanic wrote in
:

John Theune writes:

If you type in prop synch multi-engine planes into the google search
window the first hit you will see is this
The AVSIM Forums - Viewing topic #736 - Prop sync
Out of synch propellers will not be as obvious or as annoying in a
simulator as in a real plane. In most aircraft with prop synch, you
first manually ...
forums.avsim.net/dcboard.php?az=show_topic&forum=189&topic_id=736
&mode
=full - 56k - Cached - Similar pages

Go there , read it and you will know all you want to know.

Thanks. I guess people in the AVSIM forums actually answer questions
rather than just point people to Google.


Ooow 1Teh big flying circle jerk! you must be so happy there..

Bertie