Constant speed prop question

[Terence Wilson]

In the course of trying to understand how a constant speed prop works
I came across the following passage in one of the Jeppesen books:

"If the throttle is advanced without decreasing the pitch of the prop
blades to increase ___ rpm, the manifold pressure increases as the
prop mechanism attempts to keep ___ rpm constant by increasing the
blade angle. The combination of high manifold pressure and low ___ rpm
can cause damage due to high internal manifold pressures."

I found this paragraph to be confusing because it makes several
references to rpm but doesn't clarify whether it is engine or prop
rpm. The blanks were inserted by me. Can someone help me out?

Thanks in advance.

[Steven P. McNicoll[_2_]]

Terence Wilson wrote:
>
> In the course of trying to understand how a constant speed prop works
> I came across the following passage in one of the Jeppesen books:
>
> "If the throttle is advanced without decreasing the pitch of the prop
> blades to increase ___ rpm, the manifold pressure increases as the
> prop mechanism attempts to keep ___ rpm constant by increasing the
> blade angle. The combination of high manifold pressure and low ___ rpm
> can cause damage due to high internal manifold pressures."
>
> I found this paragraph to be confusing because it makes several
> references to rpm but doesn't clarify whether it is engine or prop
> rpm. The blanks were inserted by me. Can someone help me out?
>
> Thanks in advance.
>

It's engine rpm, but in direct drive engines prop rpm and engine rpm are the
same.

[Jay Maynard]

On 2008-07-20, Steven P. McNicoll > wrote:
> Terence Wilson wrote:
>> I found this paragraph to be confusing because it makes several
>> references to rpm but doesn't clarify whether it is engine or prop
>> rpm. The blanks were inserted by me. Can someone help me out?
> It's engine rpm, but in direct drive engines prop rpm and engine rpm are the
> same.

....and in geared engines, or engines with some other propeller speed
reduction unit (such as the Rotax 912), they're directly proportional. Thus,
it doesn't matter whether it's engine or prop rpm.
--
Jay Maynard, K5ZC http://www.conmicro.com
http://jmaynard.livejournal.com http://www.tronguy.net
Fairmont, MN (FRM) (Yes, that's me!)
AMD Zodiac CH601XLi N55ZC (got it!)

[Mike[_22_]]

"Terence Wilson" > wrote in message
...
> In the course of trying to understand how a constant speed prop works
> I came across the following passage in one of the Jeppesen books:
>
> "If the throttle is advanced without decreasing the pitch of the prop
> blades to increase ___ rpm, the manifold pressure increases as the
> prop mechanism attempts to keep ___ rpm constant by increasing the
> blade angle. The combination of high manifold pressure and low ___ rpm
> can cause damage due to high internal manifold pressures."
>
> I found this paragraph to be confusing because it makes several
> references to rpm but doesn't clarify whether it is engine or prop
> rpm. The blanks were inserted by me. Can someone help me out?
>
> Thanks in advance.

As others have said, unless you have a gearbox (not many planes do), they
are one and the same.

You may also want to ditch your Jepp book as the "theory" they are
describing really doesn't apply to most small piston aircraft. The old
"don't run oversquare" mentality which has been taught for years originated
out of military teachings that applied to very different pilots doing very
different things while flying very different aircraft. I run oversquare as
much as possible simply because it's more efficient. Many turbo engined
pilots routinely run 12" oversquare with no ill effects.

Here's an excellent group of articles that explains the principles involved
in easy to understand language:

http://www.advancedpilot.com/downloads/prep.pdf

[Thomas Borchert]

Terence,

> whether it is engine or prop
> rpm
>

They are connected at a fixed ratio (1:1 on direct drive engines), so
the distinction doesn't matter.

May I recommend John Deakin's engine management columns at avweb.com to
shed light on this? They are priceless in understanding your engine,
specifically these four:

Pelican's Perch #15:
Manifold Pressure Sucks!

Pelican's Perch #16:
Those Marvelous Props

Pelican's Perch #18:
Mixture Magic

Pelican's Perch #19:
Putting It All Together

http://www.avweb.com/news/pelican/182081-1.html
http://www.avweb.com/news/pelican/182082-1.html
http://www.avweb.com/news/pelican/182084-1.html
http://www.avweb.com/news/pelican/182085-1.html

--
Thomas Borchert (EDDH)

[Thomas Borchert]

Mike,

> originated
> out of military teachings that applied to very different pilots doing very
> different things while flying very different aircraft.
>

Actually, it couldn't have been all of the military. Many major cities in my
home country of Germany would contain many more historic buildings today, if
those B-17s hadn't run oversquare and lean of peak. The B-17s would never
have reached them.

--
Thomas Borchert (EDDH)

[john smith]

In article >,
Thomas Borchert > wrote:

> > originated out of military teachings that applied to very different
> > pilots doing very different things while flying very different aircraft.

> Actually, it couldn't have been all of the military. Many major cities in my
> home country of Germany would contain many more historic buildings today, if
> those B-17s hadn't run oversquare and lean of peak. The B-17s would never
> have reached them.

We can all say thank you Charles Lindberg for teaching us this technique.

[Terence Wilson]

On Sun, 20 Jul 2008 08:31:45 -0500, "Steven P. McNicoll"
> wrote:

>Terence Wilson wrote:
>>
>> In the course of trying to understand how a constant speed prop works
>> I came across the following passage in one of the Jeppesen books:
>>
>> "If the throttle is advanced without decreasing the pitch of the prop
>> blades to increase ___ rpm, the manifold pressure increases as the
>> prop mechanism attempts to keep ___ rpm constant by increasing the
>> blade angle. The combination of high manifold pressure and low ___ rpm
>> can cause damage due to high internal manifold pressures."
>>
>> I found this paragraph to be confusing because it makes several
>> references to rpm but doesn't clarify whether it is engine or prop
>> rpm. The blanks were inserted by me. Can someone help me out?
>>
>> Thanks in advance.
>>
>
>It's engine rpm

Just to clarify, it's engine rpm for all the blanks?

Thanks.

[Bertie the Bunyip[_24_]]

"Mike" > wrote in news:WPHgk.144$DS3.119@trnddc01:

> "Terence Wilson" > wrote in message
> ...
>> In the course of trying to understand how a constant speed prop works
>> I came across the following passage in one of the Jeppesen books:
>>
>> "If the throttle is advanced without decreasing the pitch of the prop
>> blades to increase ___ rpm, the manifold pressure increases as the
>> prop mechanism attempts to keep ___ rpm constant by increasing the
>> blade angle. The combination of high manifold pressure and low ___
>> rpm can cause damage due to high internal manifold pressures."
>>
>> I found this paragraph to be confusing because it makes several
>> references to rpm but doesn't clarify whether it is engine or prop
>> rpm. The blanks were inserted by me. Can someone help me out?
>>
>> Thanks in advance.
>
> As others have said, unless you have a gearbox (not many planes do),
> they are one and the same.
>
> You may also want to ditch your Jepp book as the "theory" they are
> describing really doesn't apply to most small piston aircraft. The
> old "don't run oversquare" mentality which has been taught for years
> originated out of military teachings that applied to very different
> pilots doing very different things while flying very different
> aircraft.


Actually, they dont, since most military aircraft,even smaller ones,
were supercharged and they ran well oversquare.. A 985, for instance, is
around 37 inches max and a typical cruise MP might be in the order of
25 inches with a cruise rpm of something like 1850, depending on how
fast you want to go and how much you want to burn.
The geared engines were even less relevant to this argument, since
almost everything larger than about 1500 c.i.d. was geared. The
indicated RPM was usually engine rpm and max for somthing like an 1830
was around 2400 and max MP for takeoff was about 43 IIRC and cruise was
around 30/2,000.
The practice originates from a perceived need to simplify for light
aircraft pilots new to variable pitch props.


Bertie





Bertie

[Bertie the Bunyip[_24_]]

Thomas Borchert > wrote in
:

> Mike,
>
>> originated
>> out of military teachings that applied to very different pilots doing
>> very different things while flying very different aircraft.
>>
>
> Actually, it couldn't have been all of the military. Many major cities
> in my home country of Germany would contain many more historic
> buildings today, if those B-17s hadn't run oversquare and lean of
> peak. The B-17s would never have reached them.
>

Irrelevant. They didn't run "oversquare" They ran where they were suposed
to. And they didn't run lean of peak, that engine had autolean and that
setting ran well rich of peak.





Bertie

[Bertie the Bunyip[_24_]]

John Smith > wrote in
:

> In article >,
> Thomas Borchert > wrote:
>
>> > originated out of military teachings that applied to very different
>> > pilots doing very different things while flying very different
>> > aircraft.
>
>> Actually, it couldn't have been all of the military. Many major
>> cities in my home country of Germany would contain many more historic
>> buildings today, if those B-17s hadn't run oversquare and lean of
>> peak. The B-17s would never have reached them.
>
> We can all say thank you Charles Lindberg for teaching us this
> technique.


Well, the 38 pilots in the pacific could, but leaning techniques as well as
a lot of other things about how engines work, were well known to both
manufactuers and pilots in the 30s. Some, strangely, have been lost in the
mists of time only to be "rediscovered" when things go wrong. Remember the
Lycoming crank problem? Moisture in the hollow portion of the shaft just
behind the prop?
i have several manuals, one form the 1920's , that address this problem and
guess what? The same cure recommended in the SB for the lycomings was in
those manuals.


Bertie

[Bertie the Bunyip[_24_]]

Terence Wilson > wrote in
:

> In the course of trying to understand how a constant speed prop works
> I came across the following passage in one of the Jeppesen books:
>
> "If the throttle is advanced without decreasing the pitch of the prop
> blades to increase ___ rpm, the manifold pressure increases as the
> prop mechanism attempts to keep ___ rpm constant by increasing the
> blade angle. The combination of high manifold pressure and low ___ rpm
> can cause damage due to high internal manifold pressures."
>
> I found this paragraph to be confusing

I'm not surprised. It's a **** poor explanation and actually misleading,
not to say wildly inaccurate in some places. "High internal manifold
pressures" WTF is that? The author has no understanding whatsoever ofwhat
he's talking about.


Bertie

[Mike[_22_]]

"Bertie the Bunyip" > wrote in message
...
> "Mike" > wrote in news:WPHgk.144$DS3.119@trnddc01:
>
>> "Terence Wilson" > wrote in message
>> ...
>>> In the course of trying to understand how a constant speed prop works
>>> I came across the following passage in one of the Jeppesen books:
>>>
>>> "If the throttle is advanced without decreasing the pitch of the prop
>>> blades to increase ___ rpm, the manifold pressure increases as the
>>> prop mechanism attempts to keep ___ rpm constant by increasing the
>>> blade angle. The combination of high manifold pressure and low ___
>>> rpm can cause damage due to high internal manifold pressures."
>>>
>>> I found this paragraph to be confusing because it makes several
>>> references to rpm but doesn't clarify whether it is engine or prop
>>> rpm. The blanks were inserted by me. Can someone help me out?
>>>
>>> Thanks in advance.
>>
>> As others have said, unless you have a gearbox (not many planes do),
>> they are one and the same.
>>
>> You may also want to ditch your Jepp book as the "theory" they are
>> describing really doesn't apply to most small piston aircraft. The
>> old "don't run oversquare" mentality which has been taught for years
>> originated out of military teachings that applied to very different
>> pilots doing very different things while flying very different
>> aircraft.
>
>
> Actually, they dont, since most military aircraft,even smaller ones,
> were supercharged and they ran well oversquare.. A 985, for instance, is
> around 37 inches max and a typical cruise MP might be in the order of
> 25 inches with a cruise rpm of something like 1850, depending on how
> fast you want to go and how much you want to burn.
> The geared engines were even less relevant to this argument, since
> almost everything larger than about 1500 c.i.d. was geared. The
> indicated RPM was usually engine rpm and max for somthing like an 1830
> was around 2400 and max MP for takeoff was about 43 IIRC and cruise was
> around 30/2,000.
> The practice originates from a perceived need to simplify for light
> aircraft pilots new to variable pitch props.

And that need is even more of a necessity in military trainers which have
considerably more power and are much more easily red lined. That's why I
always assumed the mentality came primarily from military instructors giving
instruction in training aircraft. At any rate the myth still persists to
this day even with instructors who should know better.

[Steven P. McNicoll[_2_]]

Terence Wilson wrote:
> On Sun, 20 Jul 2008 08:31:45 -0500, "Steven P. McNicoll"
> > wrote:
>
>> Terence Wilson wrote:
>>>
>>> In the course of trying to understand how a constant speed prop
>>> works I came across the following passage in one of the Jeppesen
>>> books:
>>>
>>> "If the throttle is advanced without decreasing the pitch of the
>>> prop blades to increase ___ rpm, the manifold pressure increases as
>>> the prop mechanism attempts to keep ___ rpm constant by increasing
>>> the blade angle. The combination of high manifold pressure and low
>>> ___ rpm can cause damage due to high internal manifold pressures."
>>>
>>> I found this paragraph to be confusing because it makes several
>>> references to rpm but doesn't clarify whether it is engine or prop
>>> rpm. The blanks were inserted by me. Can someone help me out?
>>>
>>> Thanks in advance.
>>>
>>
>> It's engine rpm
>
> Just to clarify, it's engine rpm for all the blanks?
>

Yes. Or propeller. Either would be correct as there is a fixed ratio
between engine rpm and prop rpm. In a direct drive engine that ratio is 1.

[Bertie the Bunyip[_24_]]

"Mike" > wrote in news:qNIgk.158$oU.42@trnddc07:

> "Bertie the Bunyip" > wrote in message
> ...
>> "Mike" > wrote in
>> news:WPHgk.144$DS3.119@trnddc01:
>>
>>> "Terence Wilson" > wrote in message
>>> ...
>>>> In the course of trying to understand how a constant speed prop
>>>> works I came across the following passage in one of the Jeppesen
>>>> books:
>>>>
>>>> "If the throttle is advanced without decreasing the pitch of the
>>>> prop blades to increase ___ rpm, the manifold pressure increases as
>>>> the prop mechanism attempts to keep ___ rpm constant by increasing
>>>> the blade angle. The combination of high manifold pressure and low
>>>> ___ rpm can cause damage due to high internal manifold pressures."
>>>>
>>>> I found this paragraph to be confusing because it makes several
>>>> references to rpm but doesn't clarify whether it is engine or prop
>>>> rpm. The blanks were inserted by me. Can someone help me out?
>>>>
>>>> Thanks in advance.
>>>
>>> As others have said, unless you have a gearbox (not many planes do),
>>> they are one and the same.
>>>
>>> You may also want to ditch your Jepp book as the "theory" they are
>>> describing really doesn't apply to most small piston aircraft. The
>>> old "don't run oversquare" mentality which has been taught for years
>>> originated out of military teachings that applied to very different
>>> pilots doing very different things while flying very different
>>> aircraft.
>>
>>
>> Actually, they dont, since most military aircraft,even smaller ones,
>> were supercharged and they ran well oversquare.. A 985, for instance,
>> is around 37 inches max and a typical cruise MP might be in the
>> order of 25 inches with a cruise rpm of something like 1850,
>> depending on how fast you want to go and how much you want to burn.
>> The geared engines were even less relevant to this argument, since
>> almost everything larger than about 1500 c.i.d. was geared. The
>> indicated RPM was usually engine rpm and max for somthing like an
>> 1830 was around 2400 and max MP for takeoff was about 43 IIRC and
>> cruise was around 30/2,000.
>> The practice originates from a perceived need to simplify for light
>> aircraft pilots new to variable pitch props.
>
> And that need is even more of a necessity in military trainers which
> have considerably more power and are much more easily red lined.
> That's why I always assumed the mentality came primarily from military
> instructors giving instruction in training aircraft. At any rate the
> myth still persists to this day even with instructors who should know
> better.


Well, outside of the T-34 I can't think of anything that would fit the
"square" scenario, and military instructors would not have taken any
sort of soft route with the students in any case. For instance, I happen
to know any Navy student would have to have memorised a very lengthy
series of checklists at the primary student stage for a T-28, for
instance. That's ALL of the checklists. Ever single one, emergencies and
all. And having seen them I know they were very, very complicated
indeed.
They also had to be able to touch every single switch, dial, and lever
in the airplane blindfolded. I can't see them going soft on a little
thing like not having to memorise a given MP RPM combo. Now, during
aerobatics, it would make sense to have a nominal max MP a bit shy of
normal max, as you say, but for operations outside of that, they
certainly would not have done that.
No, the only place I've ever seen he practice touted s by FBOs renting
airplanes or using them for comercial instruction.


Bertie

,

[RST Engineering]

Those cities would also have contained many more historic buildings if your
elected leaders hadn't invaded Poland, France, Czechoslovakia, and a few
other minor countries.

Jim

--
"It is the mark of an educated mind to be able to entertain a thought
without accepting it."
--Aristotle


"Thomas Borchert" > wrote in message
...

Many major cities in my
> home country of Germany would contain many more historic buildings today,
> if
> those B-17s hadn't run oversquare and lean of peak.

[Thomas Borchert]

Terence,

> Just to clarify, it's engine rpm for all the blanks?
>

There is no difference between the two. Change one, and the other
changes in the same way.

--
Thomas Borchert (EDDH)

[Thomas Borchert]

RST,

> Those cities would also have contained many more historic buildings if your
> elected leaders hadn't invaded Poland, France, Czechoslovakia, and a few
> other minor countries.
>

No doubt about it.

It seems your wink-o-meter might need adjustment.

--
Thomas Borchert (EDDH)

[Mxsmanic]

Thomas Borchert writes:

> It seems your wink-o-meter might need adjustment.

The wink-o-meter tends to cloud up when it winks at 100 million dead.

[[email protected]]

On Jul 20, 10:48 am, Bertie the Bunyip > wrote:
> "Mike" > wrote innews:qNIgk.158$oU.42@trnddc07:
>
>
>
> > "Bertie the Bunyip" > wrote in message
> ...
> >> "Mike" > wrote in
> >>news:WPHgk.144$DS3.119@trnddc01:
>
> >>> "Terence Wilson" > wrote in message
> ...
> >>>> In the course of trying to understand how a constant speed prop
> >>>> works I came across the following passage in one of the Jeppesen
> >>>> books:
>
> >>>> "If the throttle is advanced without decreasing the pitch of the
> >>>> prop blades to increase ___ rpm, the manifold pressure increases as
> >>>> the prop mechanism attempts to keep ___ rpm constant by increasing
> >>>> the blade angle. The combination of high manifold pressure and low
> >>>> ___ rpm can cause damage due to high internal manifold pressures."
>
> >>>> I found this paragraph to be confusing because it makes several
> >>>> references to rpm but doesn't clarify whether it is engine or prop
> >>>> rpm. The blanks were inserted by me. Can someone help me out?
>
> >>>> Thanks in advance.
>
> >>> As others have said, unless you have a gearbox (not many planes do),
> >>> they are one and the same.
>
> >>> You may also want to ditch your Jepp book as the "theory" they are
> >>> describing really doesn't apply to most small piston aircraft. The
> >>> old "don't run oversquare" mentality which has been taught for years
> >>> originated out of military teachings that applied to very different
> >>> pilots doing very different things while flying very different
> >>> aircraft.
>
> >> Actually, they dont, since most military aircraft,even smaller ones,
> >> were supercharged and they ran well oversquare.. A 985, for instance,
> >> is around 37 inches max and a typical cruise MP might be in the
> >> order of 25 inches with a cruise rpm of something like 1850,
> >> depending on how fast you want to go and how much you want to burn.
> >> The geared engines were even less relevant to this argument, since
> >> almost everything larger than about 1500 c.i.d. was geared. The
> >> indicated RPM was usually engine rpm and max for somthing like an
> >> 1830 was around 2400 and max MP for takeoff was about 43 IIRC and
> >> cruise was around 30/2,000.
> >> The practice originates from a perceived need to simplify for light
> >> aircraft pilots new to variable pitch props.
>
> > And that need is even more of a necessity in military trainers which
> > have considerably more power and are much more easily red lined.
> > That's why I always assumed the mentality came primarily from military
> > instructors giving instruction in training aircraft. At any rate the
> > myth still persists to this day even with instructors who should know
> > better.
>
> Well, outside of the T-34 I can't think of anything that would fit the
> "square" scenario, and military instructors would not have taken any
> sort of soft route with the students in any case. For instance, I happen
> to know any Navy student would have to have memorised a very lengthy
> series of checklists at the primary student stage for a T-28, for
> instance. That's ALL of the checklists. Ever single one, emergencies and
> all. And having seen them I know they were very, very complicated
> indeed.
> They also had to be able to touch every single switch, dial, and lever
> in the airplane blindfolded. I can't see them going soft on a little
> thing like not having to memorise a given MP RPM combo. Now, during
> aerobatics, it would make sense to have a nominal max MP a bit shy of
> normal max, as you say, but for operations outside of that, they
> certainly would not have done that.
> No, the only place I've ever seen he practice touted s by FBOs renting
> airplanes or using them for comercial instruction.
>
> Bertie
>
> ,

The whole idea of don't run oversquare is not a military technique
taught, but rather a technique taught to radial pilots back in the
day. These pilots then moved over to our flat engines, and decided
running oversquare would still be a bad idea. I agree with the other
guys-and having been through an Advanced Pilot Seminar, I can
certainly say-you will know much more about your engine after going
through the seminar. There is another seminar coming up later this
year, and I'm thinking of attending it again.
Also those pelican perch articles are fantastic, and if Deakin ever
shows up to a seminar, you get to meet the author.

[Bertie the Bunyip[_24_]]

" > wrote in news:5d086d24-406f-
:

> On Jul 20, 10:48 am, Bertie the Bunyip > wrote:
>> "Mike" > wrote innews:qNIgk.158$oU.42@trnddc07:
>>
>>
>>
>> > "Bertie the Bunyip" > wrote in message
>> ...
>> >> "Mike" > wrote in
>> >>news:WPHgk.144$DS3.119@trnddc01:
>>
>> >>> "Terence Wilson" > wrote in message
>> ...
>> >>>> In the course of trying to understand how a constant speed prop
>> >>>> works I came across the following passage in one of the Jeppesen
>> >>>> books:
>>
>> >>>> "If the throttle is advanced without decreasing the pitch of the
>> >>>> prop blades to increase ___ rpm, the manifold pressure increases
as
>> >>>> the prop mechanism attempts to keep ___ rpm constant by
increasing
>> >>>> the blade angle. The combination of high manifold pressure and
low
>> >>>> ___ rpm can cause damage due to high internal manifold
pressures."
>>
>> >>>> I found this paragraph to be confusing because it makes several
>> >>>> references to rpm but doesn't clarify whether it is engine or
prop
>> >>>> rpm. The blanks were inserted by me. Can someone help me out?
>>
>> >>>> Thanks in advance.
>>
>> >>> As others have said, unless you have a gearbox (not many planes
do),
>> >>> they are one and the same.
>>
>> >>> You may also want to ditch your Jepp book as the "theory" they
are
>> >>> describing really doesn't apply to most small piston aircraft.
The
>> >>> old "don't run oversquare" mentality which has been taught for
years
>> >>> originated out of military teachings that applied to very
different
>> >>> pilots doing very different things while flying very different
>> >>> aircraft.
>>
>> >> Actually, they dont, since most military aircraft,even smaller
ones,
>> >> were supercharged and they ran well oversquare.. A 985, for
instance,
>> >> is around 37 inches max and a typical cruise MP might be in the
>> >> order of 25 inches with a cruise rpm of something like 1850,
>> >> depending on how fast you want to go and how much you want to
burn.
>> >> The geared engines were even less relevant to this argument,
since
>> >> almost everything larger than about 1500 c.i.d. was geared. The
>> >> indicated RPM was usually engine rpm and max for somthing like an
>> >> 1830 was around 2400 and max MP for takeoff was about 43 IIRC and
>> >> cruise was around 30/2,000.
>> >> The practice originates from a perceived need to simplify for
light
>> >> aircraft pilots new to variable pitch props.
>>
>> > And that need is even more of a necessity in military trainers
which
>> > have considerably more power and are much more easily red lined.
>> > That's why I always assumed the mentality came primarily from
military
>> > instructors giving instruction in training aircraft. At any rate
the
>> > myth still persists to this day even with instructors who should
know
>> > better.
>>
>> Well, outside of the T-34 I can't think of anything that would fit
the
>> "square" scenario, and military instructors would not have taken any
>> sort of soft route with the students in any case. For instance, I
happen
>> to know any Navy student would have to have memorised a very lengthy
>> series of checklists at the primary student stage for a T-28, for
>> instance. That's ALL of the checklists. Ever single one, emergencies
and
>> all. And having seen them I know they were very, very complicated
>> indeed.
>> They also had to be able to touch every single switch, dial, and
lever
>> in the airplane blindfolded. I can't see them going soft on a little
>> thing like not having to memorise a given MP RPM combo. Now, during
>> aerobatics, it would make sense to have a nominal max MP a bit shy of
>> normal max, as you say, but for operations outside of that, they
>> certainly would not have done that.
>> No, the only place I've ever seen he practice touted s by FBOs
renting
>> airplanes or using them for comercial instruction.
>>
>> Bertie
>>
>> ,
>
> The whole idea of don't run oversquare is not a military technique
> taught, but rather a technique taught to radial pilots back in the
> day. These pilots then moved over to our flat engines, and decided
> running oversquare would still be a bad idea. I agree with the other
> guys-and having been through an Advanced Pilot Seminar, I can
> certainly say-you will know much more about your engine after going
> through the seminar. There is another seminar coming up later this
> year, and I'm thinking of attending it again.
> Also those pelican perch articles are fantastic, and if Deakin ever
> shows up to a seminar, you get to meet the author.


Nope. I've flown most of those old radials, and as I've just said, the
numbers on them weren't anything even close to square. If you can come
up with one that's even close it'd be the exception rather than the
rule. Anything that was big enough to have a variable pitch prop other
than a ground adjustable swung a prop big enough to run very low RPM or
was geared.

Also, engine management was taught at a whole different level in the
radial engine period.


Bertie
>

[Martin Hotze[_2_]]

RST Engineering schrieb:
> Those cities would also have contained many more historic buildings if your
> elected leaders hadn't invaded Poland, France, Czechoslovakia, and a few
> other minor countries.

yes, true. no discussion about that.

but it is also true that "you" bombed (with "fire bombs" [wording?])
areas within cities (mostly old parts of town with no industry but with
worth to conserve buildings) that "you" found out to be endangered due
to fire on purpose, too. So you burned down many parts of many cities on
purpose.

you knew that, too?

#m

[Bertie the Bunyip[_24_]]

Martin Hotze > wrote in
:

> RST Engineering schrieb:
>> Those cities would also have contained many more historic buildings
>> if your elected leaders hadn't invaded Poland, France,
>> Czechoslovakia, and a few other minor countries.
>
> yes, true. no discussion about that.
>
> but it is also true that "you" bombed (with "fire bombs" [wording?])
> areas within cities (mostly old parts of town with no industry but
> with worth to conserve buildings) that "you" found out to be
> endangered due to fire on purpose, too. So you burned down many parts
> of many cities on purpose.
>
> you knew that, too?
>
> #m
>

He's Bomber Harris? I thougth he was dead.


Bertie

[[email protected]]

Martin Hotze > wrote:
> RST Engineering schrieb:
> > Those cities would also have contained many more historic buildings if your
> > elected leaders hadn't invaded Poland, France, Czechoslovakia, and a few
> > other minor countries.

> yes, true. no discussion about that.

> but it is also true that "you" bombed (with "fire bombs" [wording?])
> areas within cities (mostly old parts of town with no industry but with
> worth to conserve buildings) that "you" found out to be endangered due
> to fire on purpose, too. So you burned down many parts of many cities on
> purpose.

Start a world war, overrun most of Europe, bomb the **** out of England,
and get bombed in return.

The only thing the Allies have to be sorry for is we didn't get a
working A bomb prior to June, 1944.


--
Jim Pennino

Remove .spam.sux to reply.

[Benjamin Dover]

Mxsmanic > wrote in
:

> Thomas Borchert writes:
>
>> It seems your wink-o-meter might need adjustment.
>
> The wink-o-meter tends to cloud up when it winks at 100 million dead.
>

It wouldn't be clouding up if you were one of those 100 million.

[yod-yog+ais]

On 7/20/2008 10:11 AM Mxsmanic ignored two million years of human
evolution to write:

> Thomas Borchert writes:
>
>> It seems your wink-o-meter might need adjustment.
>
> The wink-o-meter tends to cloud up when it winks at 100 million dead.

The dip****-o-meter is pegged every time you post.

[Darkwing]

"Mxsmanic" > wrote in message
...
> Thomas Borchert writes:
>
>> It seems your wink-o-meter might need adjustment.
>
> The wink-o-meter tends to cloud up when it winks at 100 million dead.

Says the idiot.

[Mortimer Schnerd, RN[_2_]]

Thomas Borchert > wrote:
> Actually, it couldn't have been all of the military. Many major cities in my
> home country of Germany would contain many more historic buildings today, if
> those B-17s hadn't run oversquare and lean of peak. The B-17s would never
> have reached them.


It's been my experience that historic buildings are vastly overrated. They
never have enough bathrooms, the stairs are too steep and electrical service is
inadequate.

Now you have nice new buildings, with the compliments of the Eighth Air Force.
Quit yer bitching.



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com

[Morgans[_2_]]

"Mortimer Schnerd, RN" <mschnerdatcarolina.rr.com> wrote
>
> Now you have nice new buildings, with the compliments of the Eighth Air
> Force. Quit yer bitching.

Actually, for once (this time) I didn't take Thomas's remarks it as
bitching.

He was observing that the Eighth Air Force did indeed have a good grip on
running over square.

Read it again, and agree, or not.
--
Jim in NC

[Tman]

Jay Maynard wrote:
> ...and in geared engines, or engines with some other propeller speed
> reduction unit (such as the Rotax 912), they're directly proportional. Thus,
> it doesn't matter whether it's engine or prop rpm.

Yes, unless there is a torque converter between the crank and the prop.

:)

[Mortimer Schnerd, RN[_2_]]

Morgans wrote:
> "Mortimer Schnerd, RN" <mschnerdatcarolina.rr.com> wrote
>>
>> Now you have nice new buildings, with the compliments of the Eighth Air
>> Force. Quit yer bitching.
>
> Actually, for once (this time) I didn't take Thomas's remarks it as
> bitching.
>
> He was observing that the Eighth Air Force did indeed have a good grip on
> running over square.
>
> Read it again, and agree, or not.



I was just having some fun with him. I don't disagree at all.



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com

[Bertie the Bunyip[_24_]]

"Morgans" > wrote in
:

>
> "Mortimer Schnerd, RN" <mschnerdatcarolina.rr.com> wrote
>>
>> Now you have nice new buildings, with the compliments of the Eighth
>> Air Force. Quit yer bitching.
>
> Actually, for once (this time) I didn't take Thomas's remarks it as
> bitching.
>
> He was observing that the Eighth Air Force did indeed have a good grip
> on running over square.
>
> Read it again, and agree, or not.


They didn't run "oversquare"


Bertie

[Morgans[_2_]]

"Mortimer Schnerd, RN" <mschnerdatcarolina.rr.com> wrote

> I was just having some fun with him. I don't disagree at all.

Okey - doekey.

I missed it. My sarcasm detector is in the shop, being fixed, at the
moment. <g>
--
Jim in NC

[Frank Olson]

Bertie the Bunyip wrote:
> Terence Wilson > wrote in
> :
>
>> In the course of trying to understand how a constant speed prop works
>> I came across the following passage in one of the Jeppesen books:
>>
>> "If the throttle is advanced without decreasing the pitch of the prop
>> blades to increase ___ rpm, the manifold pressure increases as the
>> prop mechanism attempts to keep ___ rpm constant by increasing the
>> blade angle. The combination of high manifold pressure and low ___ rpm
>> can cause damage due to high internal manifold pressures."
>>
>> I found this paragraph to be confusing
>
> I'm not surprised. It's a **** poor explanation and actually misleading,
> not to say wildly inaccurate in some places. "High internal manifold
> pressures" WTF is that? The author has no understanding whatsoever ofwhat
> he's talking about.
>
>
> Bertie


I've yet to see a normally aspirated horizontally opposed engine "blow
up" due to "high manifold pressure". I've seen governors fail (which
caused an engine overspeed), but all things being "normal", there is no
way you're going to damage your engine running with the throttle wide
open and your prop on "fine"... One of my engine checks (pre-flight) is
to cycle the prop. Is the idiot that wrote this article saying that I'm
damaging the engine when I do that???

[Bertie the Bunyip[_24_]]

Frank Olson > wrote in
news:F1zhk.23979$nD.19490@pd7urf1no:

> Bertie the Bunyip wrote:
>> Terence Wilson > wrote in
>> :
>>
>>> In the course of trying to understand how a constant speed prop
>>> works I came across the following passage in one of the Jeppesen
>>> books:
>>>
>>> "If the throttle is advanced without decreasing the pitch of the
>>> prop blades to increase ___ rpm, the manifold pressure increases as
>>> the prop mechanism attempts to keep ___ rpm constant by increasing
>>> the blade angle. The combination of high manifold pressure and low
>>> ___ rpm can cause damage due to high internal manifold pressures."
>>>
>>> I found this paragraph to be confusing
>>
>> I'm not surprised. It's a **** poor explanation and actually
>> misleading, not to say wildly inaccurate in some places. "High
>> internal manifold pressures" WTF is that? The author has no
>> understanding whatsoever ofwhat he's talking about.
>>
>>
>> Bertie
>
>
> I've yet to see a normally aspirated horizontally opposed engine "blow
> up" due to "high manifold pressure". I've seen governors fail (which
> caused an engine overspeed), but all things being "normal", there is
> no way you're going to damage your engine running with the throttle
> wide open and your prop on "fine"... One of my engine checks
> (pre-flight) is to cycle the prop. Is the idiot that wrote this
> article saying that I'm damaging the engine when I do that???
>


Well, you will do damage with a low rpm and high enough MP to raise the
BMEP to the point where knocking occurs. Knocking will apply loads that
will exceed the ability of the oil to keep the metal parts seperated and
wear the engine or even overstress parts to the point of breaking.
Observing manufacturer's limitations should ensure that knocking doesn't
occur and while there is obviously a margin included in those to account
for conditions instrument error and so forth, I know i would take care
if it were my engine!

Bertie

[[email protected]]

On Jul 23, 1:08*am, Frank Olson
> wrote:
> Bertie the Bunyip wrote:
> > Terence Wilson > wrote in
> :
>
> >> In the course of trying to understand how a constant speed prop works
> >> I came across the following passage in one of the Jeppesen books:
>
> >> "If the throttle is advanced without decreasing the pitch of the prop
> >> blades to increase ___ rpm, the manifold pressure increases as the
> >> prop mechanism attempts to keep ___ rpm constant by increasing the
> >> blade angle. The combination of high manifold pressure and low ___ rpm
> >> can cause damage due to high internal manifold pressures."
>
> >> I found this paragraph to be confusing
>
> > I'm not surprised. It's a **** poor explanation and actually misleading,
> > not to say wildly inaccurate in some places. "High internal manifold
> > pressures" WTF is that? The author has no understanding whatsoever ofwhat
> > he's talking about.
>
> > Bertie
>
> I've yet to see a normally aspirated horizontally opposed engine "blow
> up" due to "high manifold pressure". *I've seen governors fail (which
> caused an engine overspeed), but all things being "normal", there is no
> way you're going to damage your engine running with the throttle wide
> open and your prop on "fine"... *One of my engine checks (pre-flight) is
> to cycle the prop. *Is the idiot that wrote this article saying that I'm
> damaging the engine when I do that???

Unless there's a good reason to do otherwise, it would be good
practice to stay within the limits of the POH. Ours lists many
manifold pressures, (measured in inches of Hg) greater than RPM. Most
times in cruise at 5000 to 12000 feet we have rpms cranked pretty far
down with the throttle at max. 1950 rpm with our IO 360 is pretty
common.

[Robert M. Gary]

On Jul 20, 6:24*am, Terence Wilson > wrote:
> In the course of trying to understand how a constant speed prop works
> I came across the following passage in one of the Jeppesen books:
>
> "If the throttle is advanced without decreasing the pitch of the prop
> blades to increase ___ rpm, the manifold pressure increases as the
> prop mechanism attempts to keep ___ rpm constant by increasing the
> blade angle. The combination of high manifold pressure and low ___ rpm
> can cause damage due to high internal manifold pressures."

Go to you tube. There are a couple of videos out there taken from "How
its made" that shows a prop being made. They don't show the gov but
they do a great job of showing you the inside of the hub.

-Robert