Piper Archer III or Cessna 172SP

I normally fly new 172's but if I were to choose between a brand new
172sp or a Archer ? I do know that most all the 172's Ive flown that are
2002 or newer have awsome avionics. full auto pilot 4" moving map gps.
If the Archer has the equivalent. I would by the Piper. other wise Id'e
go with the Cessna. The 172 also carries alot more weight than what the
weight and balance says. Overall, I like the piper. Good luck !!!

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The Flynns wrote:
75% (that is 2700 rpm at 7500' or POH values)
I have a 62" Sensenich prop and a low time engine (170 SMOH by Mattituck)

Have you had your tach checked or calibrated recently?

I helped with the tach check at the AYA convention last
summer. We checked 3 dozen planes. Most were 100 rpm
(or more) low, with the tendency to be least accurate at
highest power settings.

Of course, your weight, temperature, and how the plane is
loaded are also factors. Suffice it to say while we loves
our Tigger, we don't see 138 kts TAS at 7500 ft. We are
usually traveling w/in 100 lbs of max gross and near-
rearward CG. 'Course it's not uncommon to be over 70 degrees
at 7000 ft here, either.

Cheers,
Sydney

I've had the tach checked and you are dead on- --100 rpm low consistently
across the range. (Ken Blackmon did the last one at annual.) I've wondered
about getting it overhauled in the winter when I get the plane painted.

In any case, I adjust for that so I'm showing 2600 rpm at 7500' or so. I
never fly near gross weight. Typically I'm loaded with 2 aboard for 300lbs,
plus 50 lbs of luggage and stuff. I've got 945 of useful so will be nearly
300lbs under gross. And sometimes another 140 under that. Last trip I
checked this out at we were at 48-58F at 7000 to 8000 coming up the
Sacramento valley in May.

Are you going to SSI?

"Sydney Hoeltzli" wrote in message
...
The Flynns wrote:
75% (that is 2700 rpm at 7500' or POH values)
I have a 62" Sensenich prop and a low time engine (170 SMOH by
Mattituck)

Have you had your tach checked or calibrated recently?

I helped with the tach check at the AYA convention last
summer. We checked 3 dozen planes. Most were 100 rpm
(or more) low, with the tendency to be least accurate at
highest power settings.

Of course, your weight, temperature, and how the plane is
loaded are also factors. Suffice it to say while we loves
our Tigger, we don't see 138 kts TAS at 7500 ft. We are
usually traveling w/in 100 lbs of max gross and near-
rearward CG. 'Course it's not uncommon to be over 70 degrees
at 7000 ft here, either.

Cheers,
Sydney

The Flynns wrote:
I've had the tach checked and you are dead on- --100 rpm low consistently
across the range. (Ken Blackmon did the last one at annual.) I've wondered
about getting it overhauled in the winter when I get the plane painted.

I think that's a good idea, or a digital tach

In any case, I adjust for that so I'm showing 2600 rpm at 7500' or so. I
never fly near gross weight. Typically I'm loaded with 2 aboard for 300lbs,
plus 50 lbs of luggage and stuff. I've got 945 of useful so will be nearly
300lbs under gross. And sometimes another 140 under that.

Yep, that's a big part of the picture. 2000 lbs vs 2400 lbs does
improve the angle of attack = more airspeed. I was really bummed
about a Tiger owner based at Sparta who claimed all sorts of wonders
in airspeed, until I realized he was always flying by himself and
partial fuel and I was always flying with the husband, the kid, and
the kitchen sink along.

Are you going to SSI?

Alas, no, but if you are please extend my greetings to Bob Steward
and have your wife give him a big hug for me and tell Mike Letrello
he's a brave man indeed (keeps trying to straighten me out as a pilot).

Cheers,
Sydney

In article W4NOa.13721$N7.2280@sccrnsc03,
"The Flynns" wrote:
I've had the tach checked and you are dead on- --100 rpm low consistently
across the range. (Ken Blackmon did the last one at annual.) I've wondered
about getting it overhauled in the winter when I get the plane painted.


I would seriously consider replacing it or supplementing it with a good
digital tach. I had the tach replaced in my PA-28-181 a few years ago
with a brand new Mitchell tach with the painted faceplate. Despite what
the calibration card said when it was installed, it didn't take long for
it to drift almost 100 RPM low at cruise. Any mechanical tach is is
going to have some drift which is only going to get worse over time.

I did not put a digital in because my mechanic at the time discouraged
it. I now basically believe that he did that because he didn't want to
do the extra work to put in the digital tach.



JKG

Jonathan Goodish wrote:
: I did not put a digital in because my mechanic at the time discouraged
: it. I now basically believe that he did that because he didn't want to
: do the extra work to put in the digital tach.

From what I understand, the digital tach is a very simple install.
It only needs power, ground, and P-leads from the ignition switch. Of
course it requires a 337 paperwork bu11$h!t, but since it's STC'd, even
that's not a big deal. My tach is about 100 RPM low (checked it myself
with a strobe tach), so I just take that into account when cruising. A
friend of mine told me once after I flew a cross-country flight and
guessed the fuel burn that I'm the only guy he knew who would be able to
tell the tach was off 100 RPM by the fuel required after the flight. It's
dead-on at 8.5 gal/hour on 180hp @ 65% (with tach correction factor).

-Cory
--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

Excellent post.
Don't forget those of us with three bladed props. Or four; whatever.
Your point illuminates elegance in thinking.

My son the musician could call RPM from the (musical) pitch.
(BTW he soloed last Monday)

Data are where you notice them; all around.

When the shock wave from the Trinity test passed,
Enrico Fermi dropped a piece of paper,
noted how far it was moved,
and got the yield right to two digits.
Regards
H.
N502TB

BTW What a choice!
Buy both.

"EDR" wrote in message
...
Oh, come on folks!
Poor man's tach check...
go out at night
fire up airplane
taxi to place on airport with mercury vapor/fluorescent light
park with light behind you
adjust engine rpm for 600/1200/1800/2400 rpm
if prop blade is not "standing still", adjust until the blad does not
move (strobe effect)

In article ,
wrote:
From what I understand, the digital tach is a very simple install.
It only needs power, ground, and P-leads from the ignition switch. Of
course it requires a 337 paperwork bu11$h!t, but since it's STC'd, even
that's not a big deal. My tach is about 100 RPM low (checked it myself
with a strobe tach), so I just take that into account when cruising. A
friend of mine told me once after I flew a cross-country flight and
guessed the fuel burn that I'm the only guy he knew who would be able to
tell the tach was off 100 RPM by the fuel required after the flight. It's
dead-on at 8.5 gal/hour on 180hp @ 65% (with tach correction factor).

I think the fact that the digital was digital is what scared him off.
He wasn't very comfortable with electronics.

I don't worry about it too much because, as you noted, I know that it's
low and take that into consideration.


JKG

"H. Adam Stevens" wrote in message ...
Excellent post.
Don't forget those of us with three bladed props. Or four; whatever.
Your point illuminates elegance in thinking.

Actually, the number of blades doesn't really matter if you can get within
the ballpark with the tach, stopping the apparrent motion will let you fine
tune it.

The real fun is that my tach reads 120/77 times what the prop is turning.

It doesn't matter how many blades the propeller has. It is dependent on
the frequency of your electrical power system. In the United States, 60
Hz is the standard. In other parts of the world, 50 Hz is used. The
United States standard is pretty tight, allowing very small deviation.
Hence multiples of 60 will strobe a moving part, making it appear
stationary

Don't forget those of us with three bladed props. Or four; whatever.
Your point illuminates elegance in thinking.

"EDR" wrote in message
...
Oh, come on folks!
Poor man's tach check...
go out at night
fire up airplane
taxi to place on airport with mercury vapor/fluorescent light
park with light behind you
adjust engine rpm for 600/1200/1800/2400 rpm
if prop blade is not "standing still", adjust until the blad does not
move (strobe effect)