The Murphy Builders Site

Hi Mike !

There was a problem with some of the early Ross drives - it was solved
by Ross shipping some new parts -- can't remember what they were, but
seem to recall a new front gear ??? Anybody else remember ????

The problem now is that Ross is out of business -- you might have
to switch to a Marcotte re-drive... a better unit by far, by all appearances.
They run about $3,500, I think. Ken ?????

The Rotax 912 has a similar vibration - the solution --
factory approved -- is NOT to idle below 2,000 RPM.
We did that for 10 years, with no problems.

--
......bobp
http://www.prosumers.ca
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.ordermygift.com

-------------------------------orig.-------------------------
On Tuesday 25 September 2007 13:28, mdb1225@comcast.net wrote:

I am thinking about buying a used Rebel with a Subaru engine and a Ross
drive.

I would appreciate anyone's thoughts on the what to watch out for and any
personal experiences.

The owner discussed a problem related to "sympathetic vibrations" causing
chattering in the Ross drive at prop rpm's below 1000. Has anyone else
experienced this?

Thanks,
Mike

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The contact for Marcotte is Ray Fiset at 418-871-3761...

Jean
Rebel 747R

Jean Poirier
Pr

Jeff Liot and Al Wick are the fellows to consult on the Ross. Al has a
pretty good web site. I wouldn't fly a Ross until taking it apart and
checking it out according to what is now known. Properly set up I'd be
quite happy with a good Ross I think but many badly need some correcting
as I understand it. I think end play on the input shaft is a big deal on
that drive. All vibrations are trying to tell you something and are
best paid attention to especially since the really hazardous torsional
vibrations may not be apparent to the pilot.
Ken

Bob Patterson wrote:

Hi Mike !

There was a problem with some of the early Ross drives - it was solved
by Ross shipping some new parts -- can't remember what they were, but
seem to recall a new front gear ??? Anybody else remember ????

The problem now is that Ross is out of business -- you might have
to switch to a Marcotte re-drive... a better unit by far, by all appearances.
They run about $3,500, I think. Ken ?????

The Rotax 912 has a similar vibration - the solution --
factory approved -- is NOT to idle below 2,000 RPM.
We did that for 10 years, with no problems.

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Ken,

Thanks

You wouldn't happen to know Al's web site address?

Mike

-------------- Original message --------------
From: Ken <klehman@albedo.net>

Jeff Liot and Al Wick are the fellows to consult on the Ross. Al has a
pretty good web site. I wouldn't fly a Ross until taking it apart and
checking it out according to what is now known. Properly set up I'd be
quite happy with a good Ross I think but many badly need some correcting
as I understand it. I think end play on the input shaft is a big deal on
that drive. All vibrations are trying to tell you something and are
best paid attention to especially since the really hazardous torsional
vibrations may not be apparent to the pilot.
Ken

Bob Patterson wrote:

Hi Mike !

There was a problem with some of the early Ross drives - it was solved
by Ross shipping some new parts -- can't remember what they were, but
seem to recall a new front gear ??? Anybody else remember ????

The problem now is that Ross is out of business -- you might have
to switch to a Marcotte re-drive... a better unit by far, by all appearances.
They run about $3,500, I think. Ken ?????

The Rotax 912 has a similar vibration - the solution --
factory approved -- is NOT to idle below 2,000 RPM.
We did that for 10 years, with no problems.

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Try
http://www.maddyhome.com/canardpages/pa ... /index.htm
Ken

mdb1225@comcast.net wrote:

Ken,

Thanks

You wouldn't happen to know Al's web site address?

Mike

-------------- Original message --------------
From: Ken <klehman@albedo.net>

Jeff Liot and Al Wick are the fellows to consult on the Ross. Al has a
pretty good web site. I wouldn't fly a Ross until taking it apart and
checking it out according to what is now known. Properly set up I'd be
quite happy with a good Ross I think but many badly need some correcting
as I understand it. I think end play on the input shaft is a big deal on
that drive. All vibrations are trying to tell you something and are
best paid attention to especially since the really hazardous torsional
vibrations may not be apparent to the pilot.
Ken

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Good site!

Thanks again

-------------- Original message --------------
From: Ken <klehman@albedo.net>

Try
http://www.maddyhome.com/canardpages/pa ... /index.htm
Ken

mdb1225@comcast.net wrote:

Ken,

Thanks

You wouldn't happen to know Al's web site address?

Mike

-------------- Original message --------------
From: Ken

Jeff Liot and Al Wick are the fellows to consult on the Ross. Al has a
pretty good web site. I wouldn't fly a Ross until taking it apart and
checking it out according to what is now known. Properly set up I'd be
quite happy with a good Ross I think but many badly need some correcting
as I understand it. I think end play on the input shaft is a big deal on
that drive. All vibrations are trying to tell you something and are
best paid attention to especially since the really hazardous torsional
vibrations may not be apparent to the pilot.
Ken

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At 01:28 PM 9/25/2007 +0000, you wrote:

I am thinking about buying a used Rebel with a Subaru engine and a Ross

drive.

I would appreciate anyone's thoughts on the what to watch out for and any

personal experiences.

The owner discussed a problem related to "sympathetic vibrations" causing

chattering in the Ross drive at prop rpm's below 1000. Has anyone else
experienced this?

Thanks,
Mike

Hi Mike I don't have any experience with ross or subaru ( other than my
car ) but 1000 prop RPM is slow enough that unless you're considering
putting the plane on floats you could always avoid the harmonic range.
Drew



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In general any significant time in this region destroys the psru and it
can do so in minutes. The forces can multiply to several orders of
magnitude higher than the engine could ever deliver. Think opera singer
shattering the wine glass. No psru is immune to destruction if operated
in the resonant range. If they are aware of the issue, most folks use a
light prop and idle their psru above typically 1200 to 2000 rpm to
attempt to stay away from the first destructive region. It seems that
some units are OK above above 1000 rpm. A heavy flywheel usually also
helps. My slightly soft Marcotte (small amount of rubber coupling)
seems happiest if I avoid below about 1700 which is effortless except
during warmup. Ross (google sdsefi) idles his above 2000. Torsional
resonance is the big risk with an uncertified engine/prop. Most of us
just don't have access to torsional testing equipment although some
estimates can be calculated if the effort is put in to measure
components. Sadly the safest thing for most of us is still to use an
engine/psru/prop combination that has been successfully operated by
others for a significant time which probably means the next harmonic was
avoided. A soft element in the drive will reduce the magnitude of the
forces but mostly they are used to attempt to tune the resonant
frequencies out of the normal operating rpm range. As I indicated
previously there are also assembly issues with the Ross psru that must
be addressed. Scary stuff but aircraft engines don't do much better;
even when pampered (and fed with a highly leaded diet) they still fail,
just for different reasons IMO.

http://www.epi-eng.com/BAS-TorVibInt.htm
http://www.vansairforce.com/community/s ... hp?t=19030

Ken

Drew Dalgleish wrote:

At 01:28 PM 9/25/2007 +0000, you wrote:

I am thinking about buying a used Rebel with a Subaru engine and a Ross

drive.

I would appreciate anyone's thoughts on the what to watch out for and any

personal experiences.

The owner discussed a problem related to "sympathetic vibrations" causing

chattering in the Ross drive at prop rpm's below 1000. Has anyone else
experienced this?

Thanks,
Mike

Hi Mike I don't have any experience with ross or subaru ( other than my
car ) but 1000 prop RPM is slow enough that unless you're considering
putting the plane on floats you could always avoid the harmonic range.
Drew

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Ken,

EPI makes a strong case for not using a subaru engine.

The Vans forum comments run 50/50.

What does Murphy Air have to say about this?

Mike

-------------- Original message --------------
From: Ken <klehman@albedo.net>

In general any significant time in this region destroys the psru and it
can do so in minutes. The forces can multiply to several orders of
magnitude higher than the engine could ever deliver. Think opera singer
shattering the wine glass. No psru is immune to destruction if operated
in the resonant range. If they are aware of the issue, most folks use a
light prop and idle their psru above typically 1200 to 2000 rpm to
attempt to stay away from the first destructive region. It seems that
some units are OK above above 1000 rpm. A heavy flywheel usually also
helps. My slightly soft Marcotte (small amount of rubber coupling)
seems happiest if I avoid below about 1700 which is effortless except
during warmup. Ross (google sdsefi) idles his above 2000. Torsional
resonance is the big risk with an uncertified engine/prop. Most of us
just don't have access to torsional testing equipment although some
estimates can be calculated if the effort is put in to measure
components. Sadly the safest thing for most of us is still to use an
engine/psru/prop combination that has been successfully operated by
others for a significant time which probably means the next harmonic was
avoided. A soft element in the drive will reduce the magnitude of the
forces but mostly they are used to attempt to tune the resonant
frequencies out of the normal operating rpm range. As I indicated
previously there are also assembly issues with the Ross psru that must
be addressed. Scary stuff but aircraft engines don't do much better;
even when pampered (and fed with a highly leaded diet) they still fail,
just for different reasons IMO.

http://www.epi-eng.com/BAS-TorVibInt.htm
http://www.vansairforce.com/community/s ... hp?t=19030

Ken

Drew Dalgleish wrote:

At 01:28 PM 9/25/2007 +0000, you wrote:

I am thinking about buying a used Rebel with a Subaru engine and a Ross

drive.

I would appreciate anyone's thoughts on the what to watch out for and any

personal experiences.

The owner discussed a problem related to "sympathetic vibrations" causing

chattering in the Ross drive at prop rpm's below 1000. Has anyone else
experienced this?

Thanks,
Mike

Hi Mike I don't have any experience with ross or subaru ( other than my
car ) but 1000 prop RPM is slow enough that unless you're considering
putting the plane on floats you could always avoid the harmonic range.
Drew

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No major kit supplier has ever endorsed alternate engines AFAIK and why
would they?? They make money if they sell you a Lyc. They know you will
fly sooner with a Lyc. and then they can blame all engine issues on
someone else. They don't really care how much gas you burn and I agree
that money should not be the motivation for an alternate engine.

But if the sport is to survive we must move out of the stone age at some
time. I don't burn leaded gas. I don't fiddle with mixture or carb heat.
It starts like a car and runs flawlessly like a car. (We still haven't
told it that it is not in a car anymore) I can get Lycoming takeoff
power and it is very happy to cruise all day at 4 gph without any
concern over temperature or fouled spark plugs. I use 5W50 synthetic
oil and I don't have to preheat so I use it more in the winter. Shock
cooling is not a concern. I paid $2k not $20k for the engine core and
will never have a $10k to $20k overhaul. Lyc. will never hold me hostage
for improper design or manufacturing. Numerous guys have over 1,000
hours on these engines. Numerous other guys have not educated themselves
and had nothing but grief. Similar story for certified Lyc's when you
think about it.

However just like you must learn how to pamper a Lyc. (or be very
wealthy), you must also pay attention when running a one of a kind power
plant. You can't turn the decisions over to an AME and you will do most
maintanance yourself.. No power plant whether certified, alternate, or
TURBOPROP is immune to torsional issues. How many guys run a non
certified prop on a certified engine thinking they are safe??

Ken

mdb1225@comcast.net wrote:

Ken,

EPI makes a strong case for not using a subaru engine.

The Vans forum comments run 50/50.

What does Murphy Air have to say about this?

Mike

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Ken,

Your points are well made and you certainly have an excellent handle on the technical aspects of the situation. I however, am completely new to this and wouldn't know a major problem if it were staring me in the face and am not as prepared mechanically to deal with this myself. However I do like the idea of not burning leaded gas and getting the same performance from an engine that burns far less fuel. My concern with the particular plane I am looking at is that the Ross redrive is from a company that is no longer in business and there may be some vibration problems that the current owner may not have resolved and I am not sure what is the right thing to do to solve it.

Mike



-------------- Original message --------------
From: Ken <klehman@albedo.net>

No major kit supplier has ever endorsed alternate engines AFAIK and why
would they?? They make money if they sell you a Lyc. They know you will
fly sooner with a Lyc. and then they can blame all engine issues on
someone else. They don't really care how much gas you burn and I agree
that money should not be the motivation for an alternate engine.

But if the sport is to survive we must move out of the stone age at some
time. I don't burn leaded gas. I don't fiddle with mixture or carb heat.
It starts like a car and runs flawlessly like a car. (We still haven't
told it that it is not in a car anymore) I can get Lycoming takeoff
power and it is very happy to cruise all day at 4 gph without any
concern over temperature or fouled spark plugs. I use 5W50 synthetic
oil and I don't have to preheat so I use it more in the winter. Shock
cooling is not a concern. I paid $2k not $20k for the engine core and
will never have a $10k to $20k overhaul. Lyc. will never hold me hostage
for improper design or manufacturing. Numerous guys have over 1,000
hours on these engines. Numerous other guys have not educated themselves
and had nothing but grief. Similar story for certified Lyc's when you
think about it.

However just like you must learn how to pamper a Lyc. (or be very
wealthy), you must also pay attention when running a one of a kind power
plant. You can't turn the decisions over to an AME and you will do most
maintanance yourself.. No power plant whether certified, alternate, or
TURBOPROP is immune to torsional issues. How many guys run a non
certified prop on a certified engine thinking they are safe??

Ken

mdb1225@comcast.net wrote:

Ken,

EPI makes a strong case for not using a subaru engine.

The Vans forum comments run 50/50.

What does Murphy Air have to say about this?

Mike

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Hi Mike !

It might help to talk to the company that built the engine
& redrive package - they have a replacement drive now ...

http://www.crossflow.com

Phone: (705) 445-5559

They may have some suggestions on evaluating the Ross.
Worst case, you could chuck it and go with the Marcotte ...
or chuck it all, and go to a Rotax 912-S .... ;-)

As for EPI's opinions - they are certainly valid for a V-8,
which is where they are coming from. A V-8 in a Rebel is just
NOT possible .... but some work very well in some Moose
installations ! :-) I didn't see anything at EPI that said
the Subaru was not a viable choice for a Rebel ...

I have flown several Subaru Rebels, and found them
to be delightfully smooth and economical, while more
than matching the power of Lyc's . There are a fair number
of Subaru Rebels flying - I have heard of no major problems,
and no accidents. There are, of course, initial setup challenges,
with cooling, cowling, etc. - already solved with the one
you are looking at .... If the price is right, you are buying
a finished airframe - with an engine thrown in ! :-)

--
......bobp
http://www.prosumers.ca
http://bpatterson.qhealthbeauty.com
http://apatterson2.qhealthzone.com
http://apatterson2.ordermygift.com

-------------------------------orig.-------------------------
On Wednesday 26 September 2007 17:43, mdb1225@comcast.net wrote:

Ken,

Your points are well made and you certainly have an excellent handle on the
technical aspects of the situation. I however, am completely new to this
and wouldn't know a major problem if it were staring me in the face and am
not as prepared mechanically to deal with this myself. However I do like
the idea of not burning leaded gas and getting the same performance from an
engine that burns far less fuel. My concern with the particular plane I am
looking at is that the Ross redrive is from a company that is no longer in
business and there may be some vibration problems that the current owner
may not have resolved and I am not sure what is the right thing to do to
solve it.

Mike



-------------- Original message --------------
From: Ken <klehman@albedo.net>

No major kit supplier has ever endorsed alternate engines AFAIK and why
would they?? They make money if they sell you a Lyc. They know you will
fly sooner with a Lyc. and then they can blame all engine issues on
someone else. They don't really care how much gas you burn and I agree
that money should not be the motivation for an alternate engine.

But if the sport is to survive we must move out of the stone age at some
time. I don't burn leaded gas. I don't fiddle with mixture or carb heat.
It starts like a car and runs flawlessly like a car. (We still haven't
told it that it is not in a car anymore) I can get Lycoming takeoff
power and it is very happy to cruise all day at 4 gph without any
concern over temperature or fouled spark plugs. I use 5W50 synthetic
oil and I don't have to preheat so I use it more in the winter. Shock
cooling is not a concern. I paid $2k not $20k for the engine core and
will never have a $10k to $20k overhaul. Lyc. will never hold me hostage
for improper design or manufacturing. Numerous guys have over 1,000
hours on these engines. Numerous other guys have not educated themselves
and had nothing but grief. Similar story for certified Lyc's when you
think about it.

However just like you must learn how to pamper a Lyc. (or be very
wealthy), you must also pay attention when running a one of a kind power
plant. You can't turn the decisions over to an AME and you will do most
maintanance yourself.. No power plant whether certified, alternate, or
TURBOPROP is immune to torsional issues. How many guys run a non
certified prop on a certified engine thinking they are safe??

Ken

mdb1225@comcast.net wrote:

Ken,

EPI makes a strong case for not using a subaru engine.

The Vans forum comments run 50/50.

What does Murphy Air have to say about this?

Mike

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Maybe but the only psru that I ever really liked from crossflow was the
Marcotte for the short time that they offered it.

I still think that Jeff Liot (and Al Wick) have instructions on how to
make the Ross safe. Jeff wouldn't be flying it otherwise. Jeff used a
heavy flywheel and I'd like to try that as well. Instructions are
probably even in the archives of the Flysoob group or the Airsoob group
on Yahoo. I suspect that evaluation is as simple as measuring how much
free play there is at the prop tips. (And whether it leaks oil).

Bob - I've seen some small V-8's ;)

Ken

Bob Patterson wrote:

Hi Mike !

It might help to talk to the company that built the engine
& redrive package - they have a replacement drive now ...

http://www.crossflow.com

Phone: (705) 445-5559

They may have some suggestions on evaluating the Ross.
Worst case, you could chuck it and go with the Marcotte ...
or chuck it all, and go to a Rotax 912-S .... ;-)

As for EPI's opinions - they are certainly valid for a V-8,
which is where they are coming from. A V-8 in a Rebel is just
NOT possible .... but some work very well in some Moose
installations ! :-) I didn't see anything at EPI that said
the Subaru was not a viable choice for a Rebel ...

I have flown several Subaru Rebels, and found them
to be delightfully smooth and economical, while more
than matching the power of Lyc's . There are a fair number
of Subaru Rebels flying - I have heard of no major problems,
and no accidents. There are, of course, initial setup challenges,
with cooling, cowling, etc. - already solved with the one
you are looking at .... If the price is right, you are buying
a finished airframe - with an engine thrown in ! :-)

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I purchased a damaged Rebel that has a Formula Power Sub engine that uses the Ross PRSU. I have not run the engine as I had originally intended to rebuild the plane. I talked to the gentleman that built this Rebel and he relayed that he had ZERO problems with the engine or the redrive. It had 303 hours on it when I purchased it from the insurance sale. I am thinkling of selling it though since I highly doubt I will ever have the time to rebuild it.

Keith R661

mdb1225@comcast.net wrote:
Ken,

EPI makes a strong case for not using a subaru engine.

The Vans forum comments run 50/50.

What does Murphy Air have to say about this?

Mike

-------------- Original message --------------
From: Ken

In general any significant time in this region destroys the psru and it
can do so in minutes. The forces can multiply to several orders of
magnitude higher than the engine could ever deliver. Think opera singer
shattering the wine glass. No psru is immune to destruction if operated
in the resonant range. If they are aware of the issue, most folks use a
light prop and idle their psru above typically 1200 to 2000 rpm to
attempt to stay away from the first destructive region. It seems that
some units are OK above above 1000 rpm. A heavy flywheel usually also
helps. My slightly soft Marcotte (small amount of rubber coupling)
seems happiest if I avoid below about 1700 which is effortless except
during warmup. Ross (google sdsefi) idles his above 2000. Torsional
resonance is the big risk with an uncertified engine/prop. Most of us
just don't have access to torsional testing equipment although some
estimates can be calculated if the effort is put in to measure
components. Sadly the safest thing for most of us is still to use an
engine/psru/prop combination that has been successfully operated by
others for a significant time which probably means the next harmonic was
avoided. A soft element in the drive will reduce the magnitude of the
forces but mostly they are used to attempt to tune the resonant
frequencies out of the normal operating rpm range. As I indicated
previously there are also assembly issues with the Ross psru that must
be addressed. Scary stuff but aircraft engines don't do much better;
even when pampered (and fed with a highly leaded diet) they still fail,
just for different reasons IMO.

http://www.epi-eng.com/BAS-TorVibInt.htm
http://www.vansairforce.com/community/s ... hp?t=19030

Ken

Drew Dalgleish wrote:

At 01:28 PM 9/25/2007 +0000, you wrote:

I am thinking about buying a used Rebel with a Subaru engine and a Ross

drive.

I would appreciate anyone's thoughts on the what to watch out for and any

personal experiences.

The owner discussed a problem related to "sympathetic vibrations" causing

chattering in the Ross drive at prop rpm's below 1000. Has anyone else
experienced this?

Thanks,
Mike

Hi Mike I don't have any experience with ross or subaru ( other than my
car ) but 1000 prop RPM is slow enough that unless you're considering
putting the plane on floats you could always avoid the harmonic range.
Drew

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---------------------------------
Be a better Globetrotter. Get better travel answers from someone who knows.
Yahoo! Answers - Check it out.



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For those looking at a subie, Maxwell Propulsion
http://www.maxwellpropulsion.com has almost or just finished testing all
the components for their EJ25 FWF. I have seen the PSRU and it does look
good. I believe it is the only one out there that is designed by an
aeronautical engineer.

Ray


On 9/26/2007 2:11 PM, im_planecrazy@yahoo.com wrote to rebel-builders:

-> I purchased a damaged Rebel that has a Formula Power Sub engine that
uses the Ross PRSU. I have not run the engine as I had originally intended
to rebuild the plane. I talked to the gentleman that built this Rebel and he
relayed that he had ZERO problems with the engine or the redrive. It had
303 hours on it when I purchased it from the insurance sale. I am thinkling
of selling it though since I highly doubt I will ever have the time to rebuild it.
->
-> Keith R661
->
-> mdb1225@comcast.net wrote:
-> Ken,
->
-> EPI makes a strong case for not using a subaru engine.
->
-> The Vans forum comments run 50/50.
->
-> What does Murphy Air have to say about this?
->
-> Mike
->
-> -------------- Original message --------------
-> From: Ken
->
-> > In general any significant time in this region destroys the psru and it
-> > can do so in minutes. The forces can multiply to several orders of
-> > magnitude higher than the engine could ever deliver. Think opera
singer
-> > shattering the wine glass. No psru is immune to destruction if operated
-> > in the resonant range. If they are aware of the issue, most folks use a
-> > light prop and idle their psru above typically 1200 to 2000 rpm to
-> > attempt to stay away from the first destructive region. It seems that
-> > some units are OK above above 1000 rpm. A heavy flywheel usually
also
-> > helps. My slightly soft Marcotte (small amount of rubber coupling)
-> > seems happiest if I avoid below about 1700 which is effortless except
-> > during warmup. Ross (google sdsefi) idles his above 2000. Torsional
-> > resonance is the big risk with an uncertified engine/prop. Most of us
-> > just don't have access to torsional testing equipment although some
-> > estimates can be calculated if the effort is put in to measure
-> > components. Sadly the safest thing for most of us is still to use an
-> > engine/psru/prop combination that has been successfully operated by
-> > others for a significant time which probably means the next harmonic
was
-> > avoided. A soft element in the drive will reduce the magnitude of the
-> > forces but mostly they are used to attempt to tune the resonant
-> > frequencies out of the normal operating rpm range. As I indicated
-> > previously there are also assembly issues with the Ross psru that must
-> > be addressed. Scary stuff but aircraft engines don't do much better;
-> > even when pampered (and fed with a highly leaded diet) they still fail,
-> > just for different reasons IMO.
-> >
-> > http://www.epi-eng.com/BAS-TorVibInt.htm
-> > http://www.vansairforce.com/community/s ... hp?t=19030
-> >
-> > Ken
-> >
-> > Drew Dalgleish wrote:
-> >
-> > >At 01:28 PM 9/25/2007 +0000, you wrote:
-> > >
-> > >
-> > >>I am thinking about buying a used Rebel with a Subaru engine and
a Ross
-> > >>
-> > >>
-> > >drive.
-> > >
-> > >
-> > >>I would appreciate anyone's thoughts on the what to watch out for
and any
-> > >>
-> > >>
-> > >personal experiences.
-> > >
-> > >
-> > >>The owner discussed a problem related to "sympathetic vibrations"
causing
-> > >>
-> > >>
-> > >chattering in the Ross drive at prop rpm's below 1000. Has anyone
else
-> > >experienced this?
-> > >
-> > >
-> > >>Thanks,
-> > >>Mike
-> > >>
-> > >>
-> > >
-> > >Hi Mike I don't have any experience with ross or subaru ( other than
my
-> > >car ) but 1000 prop RPM is slow enough that unless you're
considering
-> > >putting the plane on floats you could always avoid the harmonic
range.
-> > >Drew
-> > >
-> > >
-> >
-> >
-> >
-> >
-> >
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