Cessna 172C Performance

[Thales Coelho]

Hello,

Do anyone here have the performance tables of Cessna 172C?

I need to determine the performance penauties it will suffer operating from Carlos Prates Airport (SBPR), Brazil, with its 920m long at 3150ft runway. Average temp is around 26oC, but can reach up to 34oC or a little bit more at summer.

If someone can help me, apreciate!

[PilotDAR]

The C 172H performance table shows take off data for 5000' field elevation, at 2300 pounds GW, & 41F temperature, zero wind, ground run 1255 feet, and total to clear 50' 2480 feet. Add 10% for each 25F warmer that then stated standard temperature.

[CpnCrunch]

The C 172H performance table shows take off data for 5000' field elevation, at 2300 pounds GW, & 41F temperature, zero wind, ground run 1255 feet, and total to clear 50' 2480 feet. Add 10% for each 25F warmer that then stated standard temperature.

My actual experience is about 1500-2000ft ground run and anemic climb at full gross with similar elevation and temperature to that posted. Of course it depends how much power your 50 year old engine is actually delivering. I'd certainly recommend trying below full gross, and/or on a cooler day first, and be careful if there are any obstacles.

Should definitely be doable, but I wouldn't believe the POH numbers too much (or at least, take them as an absolute best case scenario).

[ahramin]

Also you can get a copy of the POH for your aircraft from Cessna:

http://txtav.com/en/service/technical-s ... blications

[cap41]

You could consider re pitch the propeller. 172 G climbs at 1100 FPM at 15C sea level

[Big Pistons Forever]

SBPR is 3044 MSL. 34 C there is going to be pretty marginal unless you are well below gross weight

[CpnCrunch]

You could consider re pitch the propeller. 172 G climbs at 1100 FPM at 15C sea level

I'm somewhat skeptical that you can get 1100fpm out of a 145hp 172 with a repitched prop, even with just one person on board.

[photofly]

I’m sure you can. If you don’t mind not being able to cruise faster than 80kts.

[PilotDAR]

I'm somewhat skeptical that you can get 1100fpm out of a 145hp 172 with a repitched prop, even with just one person on board.

Me too. One of my charges is a 172A taildragger with a 180 HP Lycoming, and a fine prop, and it can barely do that.

[photofly]

I get 1100fpm from my underpitched Luscombe weighing 1400lbs on 100hp. That’s the same power to weight ratio as a 145hp 172 at 2030lbs (easily doable with one on board and half tanks), and the two aircraft have the very nearly same wingspan and aspect ratio.

[PilotDAR]

Yeah, but think of how sleek and aerodynamic a Luscombe is!

[photofly]

All I can think of is that I should get a coarser prop!

[ahramin]

I changed from a 70" metal climb prop to a 72" wood cruise prop on mine a couple years ago. The difference was astounding. I used to get to 100 kts about 1500' down the runway, now it takes 4 times as far to get the same speed. I haven't actually tested the takeoff distance but it's way longer. Climb angle is less than half of what it used to be. Even in level flight the lack of acceleration is noticeable, I was shocked the first time ATC told me to keep the speed up and I opened the throttle all the way and it seemed to take forever to get to max speed. Cruise speed is 10% faster on 20% less fuel though so I'm happy. The real surprise was the climb. Vy is now 10 knots faster, and the climb rate at that speed is very close to what it used to do with the "climb" prop.

[PilotDAR]

And this is the challenge. More than most any other types, Cessnas can be operated within a range of configuration, particularly different props, and wheel fairings on or off. Yet to align the performance data with the configuration is difficult, if not impossible. The performance data usually does make a statement about the use of wheel fairings, but I have never seen Cessna data specify which prop was used. That said, Cessna has provided performance data when the design requirements did not specify that they must, and there will be a configuration (if you can figure it out) which will be accurate. I have found purported performance data for some other types, which was wildly optimistic. In one case, it turned out the the "Owner's Manual" was not the FAA approved flight manual anyway, just marketing I suspect.

Performance data should be taken with a grain of salt. Your 50 year old engine should be producing the specified power, if it is maintained according to its maintenance specifications. But, rigging, condition of the paint on the aircraft, reworking of the prop, and mods can affect performance, with no real data to rely upon.

[black hole]

you could just wail for a good headwind.

BH

[photofly]

It’s quite unlikely the engine is 50 years old, even if the airframe is.

[CpnCrunch]

It’s quite unlikely the engine is 50 years old, even if the airframe is.

Most engines are original and have just had some kind of overhaul at some point in the past (which might have been a few decades ago for a privately owned plane).

[photofly]

On my limited sample of two owned airplanes, whose ages are 78 years and 42 years, the engines are (I believe) 17 and 19 years old, respectively. If you have better sample data, I’m all ears.

Also maybe the OP could tell us how old his or her engine is!

[CpnCrunch]

On my limited sample of two owned airplanes, whose ages are 78 years and 42 years, the engines are (I believe) 17 and 19 years old, respectively. If you have better sample data, I’m all ears.

Also maybe the OP could tell us how old his or her engine is!

My limited sample is similar to yours. Although I think your 182 has Peterson conversion, which includes a new engine.

[JasonE]

My Cherokee has the original engine but it's been overhauled a few times. 6700 hours on the airframe.

[ahramin]

My aircraft is 28 years old and the engine is 45 years old.

[Thales Coelho]

SBPR is 3044 MSL. 34 C there is going to be pretty marginal unless you are well below gross weight

Thats my problem, to understand what can be my real gross weight limit.

Of course that temperature is not what we find early in the morning, neither is an everyday temp, but can reach that much.

Other problem is that the real engine will not meet the manual standards, as people reminded me here.

[photofly]

Other problem is that the real engine will not meet the manual standards, as people reminded me here.

I call bs on that theory. If it’s maintained properly, it will. The airframe may have picked up some extra drag, through rough paint, poor rigging, etc., though.

Oh - and check the equipment list to see if wheel pants were included as standard. If so, all the performance data is is with the wheelpants on. If yours are off, that’s a bunch of extra drag, too.

[CpnCrunch]

Thats my problem, to understand what can be my real gross weight limit.

Of course that temperature is not what we find early in the morning, neither is an everyday temp, but can reach that much.

Other problem is that the real engine will not meet the manual standards, as people reminded me here.

Calculate the takeoff distance using the POH and take that as the best case scenario. Then try on a cooler day, lightly loaded, and gradually experiment with hotter conditions and more load and you'll soon learn what the plane can do safely.

[PilotDAR]

Other problem is that the real engine will not meet the manual standards, as people reminded me here.

If you believe that your engine will not meet the manual standards, then you have made the determination that the engine is not airworthy, and you should not fly the plane. It could not be more simple.

The engine does not know its age, it knows how it has been maintained. If it is maintained well (in accordance with the standards), it will produce its rated power. It's simple physics. If you let its condition deteriorate, it will produce less power at full power, until eventually, it scares someone into knowing it needs maintenance. By the time it scares a pilot, it's been way too long since it should have received maintenance.

I've owned my O-200 for nearly 31 years. In that time, I've put more than 3000 hours on it. It produces the same power now, as it did when I first bought it (well, probably a little more, I bought it as a near to TBO engine). I have maintained it over the years, and it has rewarded me with dependable power the entire time, with the only exception being a stuck exhaust valve once. Otherwise, perfect reliability and performance.