Engine power question???

wrote:
I own a Cessna 150 with a 150 HP engine installed (0-320- E2D)

The STC states the static RPM is not to be over 2250 RPM.

My airplane meets the Static RPM Requirement.

My question is am I getting the full 150 HP on takeoff??? turning
2250 RPM

When rolling down the Runway the Tach reads about 2250 RPM

During stable Cruise the engine spins up to 2600 RPM ++ full
throttle : no problem

It seem's to me that the engine should turn much faster like 2700
RPM or so for 150 HP??? on takeoff Just like a Cessna 172!

Turning 2250 RPM seems like I am not getting the full rated engine
HP??? perhaps 125 HP or so???????

What sets the engine RPM?? is it the diameter of the prop?? or is
the Throttle travel
limited???

Why would the STC limit the Static Engine RPM to 2250 RPM???

is it because the Tip of the props may exceed speed of
sound ????

The STC states the Prop is a Mccauley 1C172/TM not over 74 inches
not under 72.5 inches.


Thanks for input

It forces you to use a certain minimum prop pitch to avoid overspeeding
it in flight.

An O-320 makes 120 hp at 2300 rpm and 26". At wide open throttle at SL
and 2250 it is probably around 130 hp. Add a couple thousand feet and
125 hp at the start of the roll sounds about right.

Any fixed pitch airplane is the same. A 150 with a stock O200 doesn't
have 100 hp available while static either, probably more like 80-85. So
all things being equal you still have 50% more power available than stock.

With all the old wives' tales about running constant speed engines
"oversquare" (rpm below mp) it's amusing to note that fixed pitch
aircraft are way oversquare all through their takeoff and climb phase
until they're going fast enough.

John

J.Kahn wrote:

It forces you to use a certain minimum prop pitch to avoid overspeeding
it in flight.

An O-320 makes 120 hp at 2300 rpm and 26". At wide open throttle at SL
and 2250 it is probably around 130 hp. Add a couple thousand feet and
125 hp at the start of the roll sounds about right.

Any fixed pitch airplane is the same. A 150 with a stock O200 doesn't
have 100 hp available while static either, probably more like 80-85. So
all things being equal you still have 50% more power available than stock.

You know, we ALL really ought to go get another hour in a 150 every once
in a while.

When I was in high school, the 150 was IT! WoW!

But I flew one a couple of years ago and the prevelant thought was,
"What happened? This used to be FUN".




With all the old wives' tales about running constant speed engines
"oversquare" (rpm below mp) it's amusing to note that fixed pitch
aircraft are way oversquare all through their takeoff and climb phase
until they're going fast enough.

John

cavelamb himself wrote:
J.Kahn wrote:

It forces you to use a certain minimum prop pitch to avoid
overspeeding it in flight.

An O-320 makes 120 hp at 2300 rpm and 26". At wide open throttle at
SL and 2250 it is probably around 130 hp. Add a couple thousand feet
and 125 hp at the start of the roll sounds about right.

Any fixed pitch airplane is the same. A 150 with a stock O200 doesn't
have 100 hp available while static either, probably more like 80-85.
So all things being equal you still have 50% more power available than
stock.

You know, we ALL really ought to go get another hour in a 150 every once
in a while.

When I was in high school, the 150 was IT! WoW!

But I flew one a couple of years ago and the prevelant thought was,
"What happened? This used to be FUN".




With all the old wives' tales about running constant speed engines
"oversquare" (rpm below mp) it's amusing to note that fixed pitch
aircraft are way oversquare all through their takeoff and climb phase
until they're going fast enough.

John

Actually, I'm starting to look for a 150 to play around with and for the
kids to learn in next spring. They fly about as well as most
airplanes, with a really good useful load for that size. The 150 does a
lot of things reasonably well and are becoming dirt cheap as the big
flight schools unload them. Where else can you get a 600 lb useful
load, electrics, really powerful fowler flaps, etc all for 20k.
Everybody else hates them, but I like the '64/65 straight tails. If
you block out the front half of the airplane in a picture, it looks like
an A-26.

Apparently aileron gap seals make the ailerons much lighter and
snappier, probably the biggest complaint in handling.

John

On Oct 10, 5:10 pm, "J.Kahn" wrote:
cavelamb himself wrote:
J.Kahn wrote:

It forces you to use a certain minimum prop pitch to avoid
overspeeding it in flight.

An O-320 makes 120 hp at 2300 rpm and 26". At wide open throttle at
SL and 2250 it is probably around 130 hp. Add a couple thousand feet
and 125 hp at the start of the roll sounds about right.

Any fixed pitch airplane is the same. A 150 with a stock O200 doesn't
have 100 hp available while static either, probably more like 80-85.
So all things being equal you still have 50% more power available than
stock.

You know, we ALL really ought to go get another hour in a 150 every once
in a while.

When I was in high school, the 150 was IT! WoW!

But I flew one a couple of years ago and the prevelant thought was,
"What happened? This used to be FUN".

With all the old wives' tales about running constant speed engines
"oversquare" (rpm below mp) it's amusing to note that fixed pitch
aircraft are way oversquare all through their takeoff and climb phase
until they're going fast enough.

John

Actually, I'm starting to look for a 150 to play around with and for the
kids to learn in next spring. They fly about as well as most
airplanes, with a really good useful load for that size. The 150 does a
lot of things reasonably well and are becoming dirt cheap as the big
flight schools unload them. Where else can you get a 600 lb useful
load, electrics, really powerful fowler flaps, etc all for 20k.
Everybody else hates them, but I like the '64/65 straight tails. If
you block out the front half of the airplane in a picture, it looks like
an A-26.

Apparently aileron gap seals make the ailerons much lighter and
snappier, probably the biggest complaint in handling.

John

We're at 3000' ASL here. We found the 150 to be underpowered
and really tight inside, and the O-200 would usually give top end
problems by mid-life. There were days in the summer (30°C/85°F, 5000'
DA) when the dumb thing would climb at under 200 FPM and take all day
to reach circuit altitude. They might be OK near sea level.
The older straight tails, or at least the ones without the
back window, were lighter and faster. Not many of them around now. The
150's flaps are awesome, and the rudder has enough authority to deal
with strong crosswinds, better than the 172. And it'll spin readily,
something the 172 is really reluctant to do.

Dan

wrote:
On Oct 10, 5:10 pm, "J.Kahn" wrote:

cavelamb himself wrote:

J.Kahn wrote:

It forces you to use a certain minimum prop pitch to avoid
overspeeding it in flight.

An O-320 makes 120 hp at 2300 rpm and 26". At wide open throttle at
SL and 2250 it is probably around 130 hp. Add a couple thousand feet
and 125 hp at the start of the roll sounds about right.

Any fixed pitch airplane is the same. A 150 with a stock O200 doesn't
have 100 hp available while static either, probably more like 80-85.
So all things being equal you still have 50% more power available than
stock.

You know, we ALL really ought to go get another hour in a 150 every once
in a while.

When I was in high school, the 150 was IT! WoW!

But I flew one a couple of years ago and the prevelant thought was,
"What happened? This used to be FUN".

With all the old wives' tales about running constant speed engines
"oversquare" (rpm below mp) it's amusing to note that fixed pitch
aircraft are way oversquare all through their takeoff and climb phase
until they're going fast enough.

John

Actually, I'm starting to look for a 150 to play around with and for the
kids to learn in next spring. They fly about as well as most
airplanes, with a really good useful load for that size. The 150 does a
lot of things reasonably well and are becoming dirt cheap as the big
flight schools unload them. Where else can you get a 600 lb useful
load, electrics, really powerful fowler flaps, etc all for 20k.
Everybody else hates them, but I like the '64/65 straight tails. If
you block out the front half of the airplane in a picture, it looks like
an A-26.

Apparently aileron gap seals make the ailerons much lighter and
snappier, probably the biggest complaint in handling.

John


We're at 3000' ASL here. We found the 150 to be underpowered
and really tight inside, and the O-200 would usually give top end
problems by mid-life. There were days in the summer (30°C/85°F, 5000'
DA) when the dumb thing would climb at under 200 FPM and take all day
to reach circuit altitude. They might be OK near sea level.
The older straight tails, or at least the ones without the
back window, were lighter and faster. Not many of them around now. The
150's flaps are awesome, and the rudder has enough authority to deal
with strong crosswinds, better than the 172. And it'll spin readily,
something the 172 is really reluctant to do.

Dan


Well, that's all right, I guess.
But it's sure no 65 HP Taylorcraft.
(Which gets off shorter, climbs better and is (no ****) faster!)

Richard

On Wed, 10 Oct 2007 19:10:18 -0400, "J.Kahn"
wrote:


Actually, I'm starting to look for a 150 to play around with and for the
kids to learn in next spring. They fly about as well as most
airplanes, with a really good useful load for that size. The 150 does a
lot of things reasonably well and are becoming dirt cheap as the big
flight schools unload them. Where else can you get a 600 lb useful
load, electrics, really powerful fowler flaps, etc all for 20k.
Everybody else hates them, but I like the '64/65 straight tails. If
you block out the front half of the airplane in a picture, it looks like
an A-26.

Apparently aileron gap seals make the ailerons much lighter and
snappier, probably the biggest complaint in handling.

John

Here is one you can play around with a lot.
http://saltlakecity.craigslist.org/rvs/440160765.html

Would all this work qualify as a homebuilt?

--Andy Asberry--
------Texas-----

Andy Asberry wrote:
On Wed, 10 Oct 2007 19:10:18 -0400, "J.Kahn"
wrote:

Actually, I'm starting to look for a 150 to play around with and for the
kids to learn in next spring. They fly about as well as most
airplanes, with a really good useful load for that size. The 150 does a
lot of things reasonably well and are becoming dirt cheap as the big
flight schools unload them. Where else can you get a 600 lb useful
load, electrics, really powerful fowler flaps, etc all for 20k.
Everybody else hates them, but I like the '64/65 straight tails. If
you block out the front half of the airplane in a picture, it looks like
an A-26.

Apparently aileron gap seals make the ailerons much lighter and
snappier, probably the biggest complaint in handling.

John

Here is one you can play around with a lot.
http://saltlakecity.craigslist.org/rvs/440160765.html

Would all this work qualify as a homebuilt?

--Andy Asberry--
------Texas-----

Yikes too much work....

You could license it as a homebuilt if you did something like build up
the wings from parts so you could squeeze past the 51 percent rule for
the primary structure. You would have to be able to show that you were
at least equivalent to a "quick build" kit.

Here in Canada there is a category called "Owner Maintenance" where you
can buy one that is in annual but is maybe a bit rough, and license it
as OM (it has to have a current CofA to start, then you put X's on all
the data plates) then you can maintain and repair it yourself and use
uncertified parts, like a homebuilt. The number of airplanes converted
to date is limited, probably less than 100, mainly because the FAA
refuses to acknowledge the category so OM airplanes can't travel or be
sold to the US. If they treated OM the same as second owner homebuilts,
a major impediment would be removed and a LOT of older airplanes would
be converted. On an airplane that is airworthy but ratty and therefore
cheap to buy, it's still attractive even if you can't go south.

John

J.Kahn wrote:


With all the old wives' tales about running constant speed engines
"oversquare" (rpm below mp) it's amusing to note that fixed pitch
aircraft are way oversquare all through their takeoff and climb phase
until they're going fast enough.

John

But without that manifold pressure gauge on a fixed pitch prop, us
knuckledraggers are blissfully unaware of that fact. I did see at 152
with a MP gauge once.. nice "feature".

Dave