Lycoming engine fails! Pilot survives!

On Wed, 03 Dec 2003 02:05:35 GMT, Roger Halstead
wrote:


The life of a PSRU on a piston engine has to be complicated. It not
only has to handle linear torque and thrust, but virtually any other
imaginable angle as well. Then it has to be designed to avoid any
resonances with those power train pulses AND take the positive and
negative torque without beating the snot out of the gears which means
next to nothing for slack (which brings its own set of problems).
Helical, double helical, spur, planatery...each with it's own set of
pluses and minuses.

Most manufacturers seem to take the attitude that big is strong and
bigger is stronger. In order to resist the impulses and resonances
you mention, they just design huge gears to take the load.

BUT, didn't the big 12 and 16 cylinder Vs in WWII have PSRUs? Course
those engines had very short TBOs too. Then again they weren't
exactly babied either.

Yup, the Roll Royce Merlin uses a spur gear reduction drive, driven
off a torque tube. Those gears are some big. Every single one of the
big radials also used a reduction drive, but was a planetary type, not
spur. I think the low TBO was more due to the nature of the treatment
of the engine during combat than something inherent in the design.
But come to think of it, they still don't have a very high TBO even
now, when they don't have to be run up to military power for every
takeoff.

By the way, the Rolls Royce Griffon engine was sort of two 12 cylinder
engines siamesed together for a total of 24 cylinders. I'd hate to
work on that thing.

Also...How did the guys make out using the Olds chain drive in the
Legend? It "appeared" to work great for at least a short time, but
they were running 400 to 500 HP through a chain that was used in a
drive train that only had about 200 HP on the other end. When I
talked to the one guy at Oshkosh some years back he thought it had
plenty of reserve.
I always like that airplane. Last I saw it had a turbine up front.

Sorry, that should be NSI.

I know when he used the original "so called" chevy big block aluminum
based engine he felt the front web was the weak spot. Course that was
right after planting his IV_P off the end of the runway when the web
broke. (or did he make it back on that one?) At any rate the web
broke and it was a high pucker factor.

I hadn't heard that the web broke. The story I got was that they did
some computer analysis of the engine design and factored in the prop
forces that would be transferred to the block by the PSRU and decided
to add material to the block where the PSRU bolted on. Of course, Jim
could have told me this AFTER the engine broke, don't know.

Corky Scott

"Corky Scott" wrote in message
...
On Wed, 03 Dec 2003 02:05:35 GMT, Roger Halstead
wrote:


The life of a PSRU on a piston engine has to be complicated. It not
only has to handle linear torque and thrust, but virtually any other
imaginable angle as well. Then it has to be designed to avoid any
resonances with those power train pulses AND take the positive and
negative torque without beating the snot out of the gears which means
next to nothing for slack (which brings its own set of problems).
Helical, double helical, spur, planatery...each with it's own set of
pluses and minuses.

Most manufacturers seem to take the attitude that big is strong and
bigger is stronger. In order to resist the impulses and resonances
you mention, they just design huge gears to take the load.

BUT, didn't the big 12 and 16 cylinder Vs in WWII have PSRUs? Course
those engines had very short TBOs too. Then again they weren't
exactly babied either.

Yup, the Roll Royce Merlin uses a spur gear reduction drive, driven
off a torque tube. Those gears are some big. Every single one of the
big radials also used a reduction drive, but was a planetary type, not
spur. I think the low TBO was more due to the nature of the treatment
of the engine during combat than something inherent in the design.
But come to think of it, they still don't have a very high TBO even
now, when they don't have to be run up to military power for every
takeoff.

By the way, the Rolls Royce Griffon engine was sort of two 12 cylinder
engines siamesed together for a total of 24 cylinders. I'd hate to
work on that thing.

Also...How did the guys make out using the Olds chain drive in the
Legend? It "appeared" to work great for at least a short time, but
they were running 400 to 500 HP through a chain that was used in a
drive train that only had about 200 HP on the other end. When I
talked to the one guy at Oshkosh some years back he thought it had
plenty of reserve.
I always like that airplane. Last I saw it had a turbine up front.

Sorry, that should be NSI.

I know when he used the original "so called" chevy big block aluminum
based engine he felt the front web was the weak spot. Course that was
right after planting his IV_P off the end of the runway when the web
broke. (or did he make it back on that one?) At any rate the web
broke and it was a high pucker factor.

I hadn't heard that the web broke. The story I got was that they did
some computer analysis of the engine design and factored in the prop
forces that would be transferred to the block by the PSRU and decided
to add material to the block where the PSRU bolted on. Of course, Jim
could have told me this AFTER the engine broke, don't know.

Corky Scott
Corky,
Sorry, but the Griffon was a V-12 like the Merlin, just BIGGER:

http://www.home.aone.net.au/shack_one/rolls.htm

Rick Pellicciotti
http://www.spitfire.org

Rick Pellicciotti wrote:

"Corky Scott" wrote in message
...
On Wed, 03 Dec 2003 02:05:35 GMT, Roger Halstead
wrote:


The life of a PSRU on a piston engine has to be complicated. It not
only has to handle linear torque and thrust, but virtually any other
imaginable angle as well. Then it has to be designed to avoid any
resonances with those power train pulses AND take the positive and
negative torque without beating the snot out of the gears which means
next to nothing for slack (which brings its own set of problems).
Helical, double helical, spur, planatery...each with it's own set of
pluses and minuses.

Most manufacturers seem to take the attitude that big is strong and
bigger is stronger. In order to resist the impulses and resonances
you mention, they just design huge gears to take the load.

BUT, didn't the big 12 and 16 cylinder Vs in WWII have PSRUs? Course
those engines had very short TBOs too. Then again they weren't
exactly babied either.

Yup, the Roll Royce Merlin uses a spur gear reduction drive, driven
off a torque tube. Those gears are some big. Every single one of the
big radials also used a reduction drive, but was a planetary type, not
spur. I think the low TBO was more due to the nature of the treatment
of the engine during combat than something inherent in the design.
But come to think of it, they still don't have a very high TBO even
now, when they don't have to be run up to military power for every
takeoff.

By the way, the Rolls Royce Griffon engine was sort of two 12 cylinder
engines siamesed together for a total of 24 cylinders. I'd hate to
work on that thing.

Also...How did the guys make out using the Olds chain drive in the
Legend? It "appeared" to work great for at least a short time, but
they were running 400 to 500 HP through a chain that was used in a
drive train that only had about 200 HP on the other end. When I
talked to the one guy at Oshkosh some years back he thought it had
plenty of reserve.
I always like that airplane. Last I saw it had a turbine up front.

Sorry, that should be NSI.

I know when he used the original "so called" chevy big block aluminum
based engine he felt the front web was the weak spot. Course that was
right after planting his IV_P off the end of the runway when the web
broke. (or did he make it back on that one?) At any rate the web
broke and it was a high pucker factor.

I hadn't heard that the web broke. The story I got was that they did
some computer analysis of the engine design and factored in the prop
forces that would be transferred to the block by the PSRU and decided
to add material to the block where the PSRU bolted on. Of course, Jim
could have told me this AFTER the engine broke, don't know.

Corky Scott
Corky,
Sorry, but the Griffon was a V-12 like the Merlin, just BIGGER:

http://www.home.aone.net.au/shack_one/rolls.htm

Rick Pellicciotti
http://www.spitfire.org

However, there were at least two variants of Rolls Royce Griffon engines:
1 On the Spitfire, it had a single five bladed propeller which
rotated in the reverse direction from the propeller on the
Merlin engined aircraft. I have been told that it killed a few
unwary pilots who forgot and pressed the wrong rudder pedal on
take-off. :-(
2 On the Lancaster, and on at least one single engined attack
aircraft (I can't recall the name), it was equipped with a pair
of concentric contra-rotating propellers. As you say, though,
the engine itself was similar but BIGGER.

Regards,

Peter

Corky Scott wrote:

On Fri, 21 Nov 2003 17:41:37 -0600, Big John
wrote:

Corky

Have you enough ammunition on auto engines to stop the nit picking in
this group? Both Lyc and Con started life with auto engines G

Big John

Big John, to the best of my knowledge, I try not to nitpick. I try to
present facts as I know them.

I believe that there are various auto engines that can be successfully
converted and I believe it strongly enough that I'm assembling a Ford
V6 in my shop that will be the engine I fly behind.

You weren't here when this subject was first aired many years ago, but
there were many sceptics... actually that's not a strong enough word.
There were some extremely vocal critics of the concept who felt that
no auto engine would work in an airplane. One of them was an auto
engineer, a guy who used to work for the Chaparal Racing Team with Jim
Hall. He was absolutely positive that V configured auto engines would
disintegrate (literally) under the stress. He also believed they
could not cool because the coolant passages were too small and the
cylinders too close together. He was wrong.

In order to build a reliable auto conversion, you do have to do your
homework. You have to safety wire just about everything that could
come off including the oil pan bolts. You have to build using
accepted aviation practices. There have been guys who screwed gas or
oil lines into the block and then ran them to the firewall. They
broke. You can't mount pipes solidly to the block and run them for
any distance, prop vibration will eventually crack them.

The guy who developed the Ford V6 discovered that the stud that holds
the air filter can and will unscrew and drop into the engine, if you
don't safety wire it. How did he discover this? Because it did. It
was one of the many flights in which he coasted back to the runway.

By now, many guys have successfully built and flown the Ford V6. One
guy accumulated more than 2,000 hours without anything falling off or
failing. Others are in the over a thousand hours hobbs time category.
For some reason, success stories like this don't seem to matter to
those who feel using an auto engine won't work.

I do intend to test run the engine extensively. I'm fabricating an
engine test stand along with the engine assembly process. While it's
true this doesn't exactly duplicate the stresses encountered during
flight, it's the best I can do, and better than just hanging it on the
airframe and testing the engine during the very first flight. One
thing at a time please.

Corky Scott

First, I apologize for the delayed posting in the middle of a thread.
I can only say that it has been a strange week ...

My personal view, not fully substantiated be research, is that most
(and possibly all) of the current automotive engines can be successfully
converted for aircraft use. However many of them have shortcomings that
make them less attractive.

I might not bother with an engine that I expect to have significant
vibration modes other than torsion. For example; I doubt that I would
convert any of the three cylinder engines, even if it had balance shafts,
as an inline four could be a much smoother installation. My hypothesis
is that the pitch oscillation of the three cylinder, and possibly some
of the 90 degree vee six, engines would add stresses to the propeller
and PSRU. OTOH, there are a lot of 90 degree vee six engines flying...

Probably the best question is not whether an automotive engine can be
made reliable; but whether a purpose-built engine is available and
competitively priced for the application. For example, Jabiru offers
ram air cooled engines of 80 and 120 horsepower; provided that the
aircraft is fast enough to use a 60 inch diameter prop. Rotax offers
engines with a hybrid cooling scheme...

As I recall, Blanton's conversion was originally for glider towing.
According to the story I was told, the reduction drive allowed the Ford
vee six to produce thrust similar to a much more powerful direct
drive aircraft engine--at towing speeds. Unfortunately, the story
later circulated that the engine produced mathematically ridiculous
amounts of horsepower...

So, I may eventually build with an automotive conversion. Or may not.
The choice is not "open and shut".

Regards,
Peter

Roger

Merlin (in P-51) turned 3000 rpm on take off. Prop speed was 1500 rpm
(2 to 1 reduction gearing).

Engine life was about 250+/- hrs (not in combat).

Probably happened but never heard of the reduction gearing 'going
west'. Was not a 'common' failure mode to be worrried about.

Big John


On Wed, 03 Dec 2003 02:05:35 GMT, Roger Halstead
wrote:

On Tue, 02 Dec 2003 12:57:49 GMT,
(Corky Scott) wrote:

On Mon, 01 Dec 2003 17:20:55 GMT,
(Corky Scott) wrote:

The PSRU was the one thing he felt should be done
by people who knew how to do them, and contracted NIS to develop one.

To make a long story short, the PSRU did not work well and things have
been in litigation for a while. Making a PSRU to handle 120 to 180
horsepower is one thing, making one to handle over 400 horsepower is
something entirely different.

Corky Scott


Thanks Corky,

I appreciate the info.
As I see it (and I don't know squat about PSRUs except their goal) a
high ratio PSRU as used in a turbo prop which has a very high ratio
(planetary) is easier to build than say the 2:1 or 3:1, BUT the
planetary also has the advantage in being used on an engine without
pulses being inherent in their operation.

The life of a PSRU on a piston engine has to be complicated. It not
only has to handle linear torque and thrust, but virtually any other
imaginable angle as well. Then it has to be designed to avoid any
resonances with those power train pulses AND take the positive and
negative torque without beating the snot out of the gears which means
next to nothing for slack (which brings its own set of problems).
Helical, double helical, spur, planatery...each with it's own set of
pluses and minuses.

BUT, didn't the big 12 and 16 cylinder Vs in WWII have PSRUs? Course
those engines had very short TBOs too. Then again they weren't
exactly babied either.

----clip----

On Wed, 03 Dec 2003 15:13:03 GMT, Peter Dohm
wrote:


However, there were at least two variants of Rolls Royce Griffon engines:
1 On the Spitfire, it had a single five bladed propeller which
rotated in the reverse direction from the propeller on the
Merlin engined aircraft.




I have been told that it killed a few
unwary pilots who forgot and pressed the wrong rudder pedal on
take-off. :-(

Regards,

Peter
++++++++++++++++++++++++++++++++

Really.

Who told you such?
Sounds like wannabee myth and legend
without some serious documentation.


Barnyard BOb - over 50 years of successful flight

"karel adams" wrote in message
...

. . . he's certainly a serious guy with a lot of flying hours (though less
than UB of course)
and he's a university teacher besides.

He's a pilot AND a university teacher? And you believe ANYTHING he says?
Wow!

Rich S.

"RR Urban" wrote in message
...
On Wed, 03 Dec 2003 15:13:03 GMT, Peter Dohm
wrote:


However, there were at least two variants of Rolls Royce Griffon engines:
1 On the Spitfire, it had a single five bladed propeller which
rotated in the reverse direction from the propeller on the
Merlin engined aircraft.



All Griffon engines rotated in the opposite direction of the Merlin.


I have been told that it killed a few
unwary pilots who forgot and pressed the wrong rudder pedal on
take-off. :-(

Regards,

Peter
++++++++++++++++++++++++++++++++

I don't believe this for a minute. Pilots put in rudder inputs based on
what the airplane is DOING, not what it is expected to do. I fly an
airplane (from time to time) that requires full left rudder at the start of
the takeoff roll (Nanchang CJ-6, left turning engine, non steerable nose
wheel). When I get out of it and get back in my Waco (right turning engine,
tailwheel) I don't start steering it to the left automatically, I do
whatever I have to do with the rudders to keep it straight.

There have been many times that I needed full left rudder at the start of my
takeoff with the Waco (hard crosswind from the right).

Rick Pellicciotti

On Wed, 3 Dec 2003 08:27:25 -0600, "Rick Pellicciotti"
wrote:


Sorry, but the Griffon was a V-12 like the Merlin, just BIGGER:

http://www.home.aone.net.au/shack_one/rolls.htm

Rick Pellicciotti
http://www.spitfire.org


Sorry, my bad. I was thinking of the Napier Sabre type H engine.

It was used in the Typhoon and Tempest.

See: http://www.eagle.ca/~harry/aircraft/tempest/sabre/

Corky Scott

I have been told that it killed a few
unwary pilots who forgot and pressed the wrong rudder pedal on
take-off. :-(

Regards,

Peter
++++++++++++++++++++++++++++++++

Really.

Who told you such?
Sounds like wannabee myth and legend
without some serious documentation.

I was told about serious difficulties for pilots converting
(though not about casualties ) in exactly this story
in my PPL ground course. The teacher's identity
is available though not on this forum, but he's certainly
a serious guy with a lot of flying hours (though less than UB of course)
and he's a university teacher besides.

Just before this, he had explained that the TO procedure
for powerful fighters like the P51 Mustang prescribed
several precise steps of adding power and corrective steering,
with lifting the tail somewhere in between.

KA - first flight real soon now
+++++++++++++++++++++++++++++++++++++++++++

Sorry Karel,
All really experienced pilots I know... just FLY THE AIRPLANE
when they are through reading 'the book'.

Your instructor may be a serious guy as a professor, but as a
first class pilot, I have some reservations. Read Rick Pellicciotti's
post and you will be on the right track, IMHO.

Maybe BIg John, as an experienced P-51 pilot, will add
to your knowledge base about P-51 TO procedures.
By the book....AND by his personal experience.
What say you, John? g

FWIW....
No question, the military has 'numbers' for everything.
As aviation cadets in the '50's, the USAF had us
memorize tons and tons of precise numbers.
****... they even had exact procedures for us
underclassmen on how to eat a military meal.

It was a bitch Karel, a real bitch !
Half the guys washed out early on.

Barnyard BOb - first flight way over 50 years ago.