Cessna climbs that much better than a Cherokee ?

Indiana_Pilot

Indiana_Pilot

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I finally took the time to get checked out in a Cessna 172M and flew it for a few hours.. (same O-320 as my Cherokee)

This plane leaps off of the ground even faster than a Cherokee configured for short field take offs..

Is this wing really that much more efficient or is there a hidden jet engine in the back of this thing ?? :D
 
Sorry.. ya it's a 68' Hershey Bar... but even the later tapered wing models I have flown don't perform like the Cessna 172..
 
Firefighter_324 said:
I finally took the time to get checked out in a Cessna 172M and flew it for a few hours.. (same O-320 as my Cherokee)

This plane leaps off of the ground even faster than a Cherokee configured for short field take offs..

Is this wing really that much more efficient or is there a hidden jet engine in the back of this thing ?? :D
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Cessna winds the rubber bands tighter. :D
 
172Ms, with their little 145 HP engines, are also more spright than the later 180 HP 172SPs.

They are considerably lighter, and they can carry more passenger weight as well.
 
At our FBO, the 172M with the 180hp engine puts the 200hp Arrow III to shame.
 
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MAKG1 said:
172Ms, with their little 145 HP engines, are also more spright than the later 180 HP 172SPs.

They are considerably lighter, and they can carry more passenger weight as well.
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Where have you seen a 145 horse 172M :confused:
 
That's strange you find that. I've only flown a 172r model with the 180hp engine. I recently purchased a 68 cherokee 180. My cherokee will climb out with full fuel, me, and another pax at 1200fpm at 85mph. I never saw that performance out of the 172..
 
A 172 has more wing (174 sq ft area) than does a square-wing Cherokee 140/150/160/180 (160 sq. ft.). 172's wing has a higher aspect ratio, which generally makes a wing more efficient. Cherokee's airfoil is easier to build and conveniently allows the spar carry-through to traverse the cabin out of the way under the rear seat, and gives reasonable cruise performance and stall handling -- but it increases drag rapidly at high angles of attack.
 
Firefighter_324 said:
I finally took the time to get checked out in a Cessna 172M and flew it for a few hours.. (same O-320 as my Cherokee)

This plane leaps off of the ground even faster than a Cherokee configured for short field take offs..

Is this wing really that much more efficient or is there a hidden jet engine in the back of this thing ?? :D
Click to expand...

The 172 has a lower stall speed and Vx & Vy are slower than the PA-28. PA-28 will go a little faster. Design trade-offs.

On thing to note is the PA-28 is sensitive in terms of being on speed for climbs. Play around with it (vary your airspeed a knot or two) and find the best climb rate. Since I fly out of an airport with a ground elevation of 5,500' and I'm generally 500 pounds under gross I climb about three to five knots slower than book and get the book rate of 1,000 fpm at about 95% power. I don't generally use 100% with the turbo and the long runways we have in this part of the world.

When I was flying a 172 it was usually near gross (full fuel w/instructor) and didn't know enough to find the actual Vy. That said, climb rates in the school's planes varied a couple hundred fpm at the book Vy. Engine condition and prop pitch do matter.

If your cherokee's prop is pitched for cruise rather than climb it will be slow. What's your engine speed and have you checked the tach for accuracy? Tachs generally indicate low unless they've been overhauled in the last decade or so.
 
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MAKG1 said:
You're right. They are 150 HP from the factory. Still more capable than 172s with larger engines.
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172M (stock): 150 hp, 2300 lb MGW = 15.3 lb/hp power loading
172S: 180 hp, 2550 lb MGW = 14.2 lb/hp power loading

I've not flown a 172S, but I'm not aware of anything aerodynamically different about the 172S that would prevent it from performing better with its lower power loading at MGW, all else being equal.

Now if you're talking about heavier empty weight, yes, that impacts useful load.
 
Dumb question.. Where is the prop marked for the pitch? I assume the spinner will need to come off? It seems pretty lethargic on climbs when more than I am in there
 
Pilawt said:
172M (stock): 150 hp, 2300 lb MGW = 15.3 lb/hp power loading
172S: 180 hp, 2550 lb MGW = 14.2 lb/hp power loading

I've not flown a 172S, but I'm not aware of anything aerodynamically different about the 172S that would prevent it from performing better with its lower power loading at MGW, all else being equal.

Now if you're talking about heavier empty weight, yes, that impacts useful load.
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Empty weight is a huge factor. Many of us typically fly with one or two people in the aircraft; my Cherokee 180 is 300 to 400 pounds lighter than a new build 172SP with about the same fuel capacity. Thus, for a given payload I'm generally lugging around 300 to 400 pounds less total weight giving me an impressive performance gain versus the 172. Same reason why my Cherokee out climbs a 200hp arrow.

That said, it seems that added horsepower seems to have a bigger impact on PA28s than 172s. I fly a mixed fleet of 172Ps and the 160hp vs 180hp models have some differences but it is very close.

The difference between the Cherokee 140-160 I gave a BFR in recently and my Cherokee 180 of the same model year makes them feel like dramatically different airplanes.
 
Were they both 150hp? FBO used to have two 172M's that I rented, one had the 160hp upgrade and the other was 150hp, very noticeable difference between them. The 150hp also had a lot more time on the engine, maybe it was getting tired too.
 
Pilawt said:
172M (stock): 150 hp, 2300 lb MGW = 15.3 lb/hp power loading
172S: 180 hp, 2550 lb MGW = 14.2 lb/hp power loading

I've not flown a 172S, but I'm not aware of anything aerodynamically different about the 172S that would prevent it from performing better with its lower power loading at MGW, all else being equal.

Now if you're talking about heavier empty weight, yes, that impacts useful load.
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Keep in mind, you don't make that 180 HP at takeoff. You have to get the engine to the redline for that. Typically, it will be 2300 RPM at the start of the roll, and go up to 2500 RPM at Vy.

I've flown M, N, R, and S models. I find I can squeeze more people into the M than the other models, and get somewhat better climb performance. The reason seems to be avionics and fuel weight, especially in the S "Nav III" models.

As you know, you can get the best of both worlds by putting the later engine in an earlier (lighter) airframe. People do this with 172Ns all the time, and make very capable airplanes with more than 1000 lb passenger weight with full fuel. And they even do (very) well at Lake Tahoe (BTDT) or flying over the Cascades at 10,000 (BTDT, too).

The only real complaint about M models I have is the momentary flap switch. I prefer the paddle.
 
MAKG1 said:
Keep in mind, you don't make that 180 HP at takeoff. You have to get the engine to the redline for that. Typically, it will be 2300 RPM at the start of the roll, and go up to 2500 RPM at Vy.
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Same issue with the 172M's O-320.

I've flown M, N, R, and S models. I find I can squeeze more people into the M than the other models, and get somewhat better climb performance. The reason seems to be avionics and fuel weight, especially in the S "Nav III" models.
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The new interiors, seats, upholstery, etc., are heavier, too.

As you know, you can get the best of both worlds by putting the later engine in an earlier (lighter) airframe. People do this with 172Ns all the time, and make very capable airplanes with more than 1000 lb passenger weight with full fuel. And they even do (very) well at Lake Tahoe (BTDT) or flying over the Cascades at 10,000 (BTDT, too).
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I know that well. I have one. I like short fields and have no friends, so I opted out of the gross weight increase STC SA2196CE. The airplane has 180 hp and 40° flap, but only 2300 lb MGW. It climbs like crazy.
 
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This is a great conversation. I have often wondered about the differences between two of the most common GA - rental - airplanes.
 
So what is the max horsepower for the O-320.. My Cherokee is supposed to be 150 but it seems like the rental Skyhawk has alot more power.. Seems more than just propeller pitch.
 
I cannot contain myself. This thread begs my input. I have spent a lifetime instructing in Cessnas and Cherokees. In general, Cessnas always beat the Cherokees. There can be different in specific make/ models, but in general, Cessnas always beat the Cherokees.
 
Pilawt said:
There are different variants of the O-320.

Models 172I - 172M (1968-76): O-320-E2D, 150 hp, ok to run on 80 octane fuel.

Model 172N (1977-80): O-320-H2AD, 160 hp, 100LL fuel only.

Model 172P (1981-86): O-320-D2J, 160 hp, 100LL fuel only.
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So does the 150 horse Cardinal climb better or worse than a Cherokee?

I've never flown a Cherokee so I wouldn't know. I just flew a 150 horse 177 160 NM and flew back a 177B (180 horse/constant speed) the same distance. The climb different isn't night vs day. Hot weather probably is much more noticeable.
 
bnt83 said:
So does the 150 horse Cardinal climb better or worse than a Cherokee?
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Oooh, lots of variables to play with here, and lots of apples and oranges bouncing around. Among them:

C-177 (150 hp) = 2350 lb MGW;
PA-28-140 and PA-28-150 (150 hp, Hershey-bar wing) = 2150 lb MGW;
PA-28-151 (150 hp taper-wing Cherokee Warrior) = 2325 lb MGW.

My recollection (renting 150 hp Cardinals when they first came out; and hundreds of hours instructing in Cherokee 140s) is that neither would set the world on fire with its climb, but the Cardinal was marginally better. Longer span, more wing area, higher aspect ratio probably made the difference.

Unlike the Cherokee, the Cardinal had a huge cabin which begged to be overloaded, leading to its "doggy" reputation.
 
Pilawt said:
172M (stock): 150 hp, 2300 lb MGW = 15.3 lb/hp power loading
172S: 180 hp, 2550 lb MGW = 14.2 lb/hp power loading

I've not flown a 172S, but I'm not aware of anything aerodynamically different about the 172S that would prevent it from performing better with its lower power loading at MGW, all else being equal.

Now if you're talking about heavier empty weight, yes, that impacts useful load.
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Stock cherokee 180 at gross 2400# = 13.3 lb/hp
My normal load is 2000# or 11.1 lb/hp

I'm not sure what these numbers mean or how important they are. What's the impact of wing loading?
 
Firefighter_324 said:
Dumb question.. Where is the prop marked for the pitch? I assume the spinner will need to come off? It seems pretty lethargic on climbs when more than I am in there
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Not really, check the paperwork - should be in the POH and/or the STC. The low-end cherokees did not have climb props, you had to have an STC for it. Check the TCDS and you'll see what props were allowed.
 
per the book numbers. (2500 airport, 5000ft cruise)
172H PA28-140
TO 1040ft 1500ft
TO obs 1910ft 2300ft
Landing 570 ft 580ft
Landingo 1310ft 1140ft
Cruise 136mph 137mpg

per the book the Cherokee needs more runway for Take off. I always thought the Cherokee was about 10mph faster than the Cessna, but it doesn't show up that way in the book numbers.

Brian
 
With our high elevation and high terrain locally 180hp is a good minimum. At that an old 172 does ok but an old Cherokee is painfully slow. You don't see Cardinals come up here, too little margin.
 
CharlieTango said:
With our high elevation and high terrain locally 180hp is a good minimum. At that an old 172 does ok but an old Cherokee is painfully slow. You don't see Cardinals come up here, too little margin.
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Cardinal RGs aren't bad up there. BTDT. Even on a hot day at Lee Vining. But that's 200 HP instead of 150...

CAP recently searched a down Cherokee, successfully, above the tree line near Mt. Whitney, in late summer. The pilot claimed his prop separated. I have to admit, my first thought was "Oh God, a Cherokee at 11000+ feet?"
 
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