Throttle or Prop control first after takeoff

In article ,
"Charlie Gibbs" wrote:

In article ,
(dcd) writes:

On Saturday, March 7, 2009 9:41:21 AM UTC-8, Danny Deger wrote:

The POH on my 1941 Taylorcraft doesn't say a thing about when to
adjust the prop :-)

I didn't think the 1941 Taylorcraft came with a POH? Do you still
have it?

I once managed to purchase a new POH for my 1961 172B. But it
doesn't say anything about when to adjust the prop either.

As for planes with constant-speed props, my rule on takeoff is to
bring back the power first - although this shouldn't be necessary
if the airport is at 5000 feet. :-)

I have a controllable Hartzell (no governor), so I have to adjust the
RPM so as not to overspeed the prop, leaving full throttle on takeoff.

The "throttle before prop" is a holdover from military days, when those
airplanes had superchargers, which would allow for overboosting the
cylinders, sometimes with disastrous outcomes.

Normally-aspirated engines are quite tolerant of reasonable RPM
reductions, while maintaining full throttle. Just look at those planes
with fixed-pitch cruise props -- the only control you have is the
throttle, and they allow full throttle on takeoff.

On Mar 6, 7:31 pm, "BT" wrote:

The thing about "older" POH, like your 1965 C-210.. they were not that
explict.

Dependent on the engine, some say keep RPM higher than MP, some don't.

But moving the controls in the wrong order can put the engine
outside its operational limitations. For instance, if the POH allows
24" and 2200 RPM, that setting isn't within the old "square" rule-of-
thumb but it won't hurt the engine. Now, if you pull the prop back to
2200 with the throttle wide open, you're going to get may 25 or 26" MP
and 2200 RPM, well outside the limits set by the manufacturer. The
risk with large-bore, slow-turning engines is detonation, and the POH
tables are designed with avoiding detonation and the awesome damage it
causes.
So that's why we teach people to avoid high cylinder pressures
by reding MP first, then setting RPM. If increasing power, get the RPM
up first and then increase MP.
It's no different than upshifting or downshifting your car; you
don't just mash the throttle to the floor when you come to a steep
hill; you downshift first and then apply the power, and when you get
to the top of the hill you don't upshift until the car's speed is such
that the engine won't have to drop to some very low RPM when you let
the clutch out and apply the power again.
We older guys can remember a time when cars would "ping" or
"knock" when the engine was driven at a low RPM and too much throttle.
That was detonation and it would break rings and knock holes in
pistons and trash the bearings and sometimes heads and cylinder walls
would crack. It was considered very poor driving technique. Now we
have cars with computers and knock sensors and all sorts of electronic
wizardry that keeps the driver from breaking stuff, but it also dumbs
down young drivers and they can't grasp the RPM/MP thing quite so
easily. And automatic transmissions and ABS brakes have made driving
habits even worse, IMHO.

Dan

In article
,
says...


We older guys can remember a time when cars would "ping" or
"knock" when the engine was driven at a low RPM and too much throttle.
That was detonation and it would break rings and knock holes in
pistons and trash the bearings and sometimes heads and cylinder walls
would crack.



Careening wildly off course here, but in truth the evidence is not that
clear-cut about the damage done to automobile engines from "knocking".
Recalling my UofM courses on the subject, the text even reproduced a study
of tear-down examination of engines after many hours of heavy knocking in
a laboratory controlled environment, and the results were inconclusive as
concerns damage to engine components.

The main concern with knocking, in car engines, is that once IMEP exceeds
KLIMEP the power starts to fall off rapidly; therefore this represents an
absolute performance limitation for any engine.

I am willing to accept that things are different in the world of aircraft
engines, where slow rotational speeds and turbocharging may lead to
extreme detonation conditions, if mismanaged.


Sources:
http://www.me.umn.edu/education/courses/me5461/

Internal Combustion Engines, by Richard Stone, 3rd Edition, SAE 1999

On Mar 6, 7:31*pm, "BT" wrote:

Some one already mentioned the take off procedure for the C-182T (Turbo).
Reduce the MP and the Fuel Flow to the Top of the Green.

That is true but the C-182T is *not* turbo.

-Robert

How about Cessna T182T NAV III
BT

"Robert M. Gary" wrote in message
...
On Mar 6, 7:31 pm, "BT" wrote:

Some one already mentioned the take off procedure for the C-182T (Turbo).
Reduce the MP and the Fuel Flow to the Top of the Green.

That is true but the C-182T is *not* turbo.

-Robert

"Robert M. Gary" wrote in message
...
On Mar 6, 7:31 pm, "BT" wrote:

Some one already mentioned the take off procedure for the C-182T (Turbo).
Reduce the MP and the Fuel Flow to the Top of the Green.

That is true but the C-182T is *not* turbo.

Can be. Mine is.

--
Dan

T182T at 4R4

On Sat, 14 Mar 2009 11:23:28 -0500, "Dan Luke"
wrote:


"Robert M. Gary" wrote in message
...
On Mar 6, 7:31 pm, "BT" wrote:

Some one already mentioned the take off procedure for the C-182T (Turbo).
Reduce the MP and the Fuel Flow to the Top of the Green.

That is true but the C-182T is *not* turbo.

Can be. Mine is.

I do believe that unless filing a flight plan, technically, that's a
T182T, not a C182T.

A bit pedantic, yes, but still.

"Peter Clark" wrote in message
...
On Sat, 14 Mar 2009 11:23:28 -0500, "Dan Luke"
wrote:


"Robert M. Gary" wrote in message
...
On Mar 6, 7:31 pm, "BT" wrote:

Some one already mentioned the take off procedure for the C-182T
(Turbo).
Reduce the MP and the Fuel Flow to the Top of the Green.

That is true but the C-182T is *not* turbo.

Can be. Mine is.

I do believe that unless filing a flight plan, technically, that's a
T182T, not a C182T.

A bit pedantic, yes, but still.

And if filing a flight plan.. it is neither.. but most likely a C-182/G
(with NAV III package)
and ATC does not care if it is turbo or not.


BT

On Mar 14, 9:23*am, "Dan Luke" wrote:
"Robert M. Gary" wrote in ...
On Mar 6, 7:31 pm, "BT" wrote:

Some one already mentioned the take off procedure for the C-182T (Turbo).
Reduce the MP and the Fuel Flow to the Top of the Green.
That is true but the C-182T is *not* turbo.

Can be. Mine is.

--
Dan

T182T at 4R4

No, yours is a C-T182T.

-Robert

In article ,
says...


On Mar 14, 9:23*am, "Dan Luke" wrote:
"Robert M. Gary" wrote in
..
..
On Mar 6, 7:31 pm, "BT" wrote:

Some one already mentioned the take off procedure for the C-182T (Turbo).
Reduce the MP and the Fuel Flow to the Top of the Green.
That is true but the C-182T is *not* turbo.

Can be. Mine is.

--
Dan

T182T at 4R4

No, yours is a C-T182T.

-Robert

Yes, now that Skylanes have reached the "T" designation it gets confusing.
They should have avoided it - like numbering conventions that avoid I's that
can be taken for 1's and O's that can be taken for 0's. They should have gone
directly to "U". The question becomes, for these models that remain in
production for the better part of a century, what happens after "Z"?
C-T182-AA"? With that we're set for a good long time!