To add to this, Vx increases with altitude, Vy decreases with altitude, Vx = Vy at the aircraft theoretical ceiling. In other words, maintaining sea level Vy is not gonna take you there in the shortest time (if at all).
I agree. I am new and also working my way through the tutorials, and have not seen any mention of “leaning”.
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As an old 152 student pilot I can say it’s tough to get a 152 up to 8000.
It can be done but weight and density altitude will make a difference.
You can lean the mixture to get more power but watch your EGT.
IRL I remember flying a 172 in the mountains in Vegas with 4 people and I couldn’t hold 5000 ft without the stall horn going off.
Here are some descriptions about why leaning is required : Aircraft Engine Leaning Procedures & Ground Operations
In the real aircraft I do a very restrictive leaning when passing 5.000 feet. But, you need to watch your EGT temps!
I usually do enroute climbs at 75 kt. Climb rate is what it is so to speak. Speed is the value to focus on, not climb rate. At 8.000 feet I would guess 250-400fpm is normal depending on air density and aircraft load.
Same problem here. This must be a bug. All other lessons are ok.
There is nothing about adjustment of carb other than full throttle
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I hit two issues in the tutorials. Take off climb rate - I had to turn off the carb heater to reach the desired height in time (I found this googling somewhere). In the VFR climb to 8000, I was trying to do this while maintaining the take off heading and I couldn’t. If I turned so I stayed near the airport I could reach 8000 without it saying I had gone too far away.
What is going on with the EGT temps? I have never flown any single engine piston where you need to keep a watch on the EGT. Of course you can use EGT for leaning (some aircraft don’t even have an EGT gauge), but watch the EGT like there is some kind of EGT limit? Never heard of it.
From wikipedia : An exhaust gas temperature gauge (EGT gauge or EGT sensor) is a meter used to monitor the exhaust gas temperature of an internal combustion engine in conjunction with a thermocouple-type pyrometer. EGT gauges are found in certain cars and aeroplanes. By monitoring EGT, the driver or pilot can get an idea of the vehicle’s air-fuel ratio (AFR).
At a stoichiometric air-fuel ratio, the exhaust gas temperature is different from that in a lean or rich air-fuel ratio. At rich air-fuel ratio, the exhaust gas temperature either increases or decreases depending on the fuel. High temperatures (typically above 1,600 °F or 900 °C) can be an indicator of dangerous conditions that can lead to catastrophic engine failure.
I think the leaning is more precise with an EGT so that you can keep the best temperature in the cylinders.
I know what an EGT indicator is, you can indeed set the mixture more precisely with an EGT gauge. The EGT itself doesn’t mean anything, you’ll need to find the peak EGT and then either lean a little further or enrich the mixture slightly for best economy or best power mixture (respectively).
Regarding temperature in the cylinders and engine damage you’ll need to keep an eye on the Cylinder Head Temperature (CHT), EGT does not give much information about the actual cylinder temperature.
As for other comments I’ve read about carburetor heat, keep it OFF for climb! I don’t know what faulty theories lie behind that but carburetor heat will reduce engine power, not improve it. The only time it will improve performance is when you have carb. ice which is not an issue at high power settings during climb.
Regarding best angle and best rate of climb speeds, they are usually given for sea level. Be aware that during climb the Vx will increase while the Vy will decrease with altitude. At the aircraft theoretical ceiling Vx = Vy.
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I have never seen a CHT gauge in a 152, which is the topic here.
Where a CHT gauge is unavailable, EGT is typically available. All the 152’s and 172’s had EGT’s in my flying club, and it was stressed to keep an eye on it to avoid warping the valves and pitting the pistons.
These engines are air cooled. I can’t remember the initial mixture setting, but I want to say it was 2 full turns out to get going. It should be in the POH.
But to be fair, the hot EGT gas comes from the cylinders themselves. So while much slower to respond and at much values, the CHT is relatively “linked” to EGT. I’ve never seen (or can think of) a situation where once temperatures are stable, increasing EGT decreases CHT or vice versa. So the EGT is a good indicator of how much thermal energy you are exposing the cylinder head to. If you are seeing extreme EGT way above normal cruise levels (Say you lean for peak EGT at wide open throttle @ sea level) you can assume the CHT is going to be climbing rapidly and you want to get that sorted right away. Obviously its better to have an actual CHT gauge, but I personally disagree with the statement that EGT “doesn’t mean anything”.
Exactly, you should stay away from peak EGT. The EGT itself in C or F does not mean anything. You’ll need to find the peak EGT and then fly either slightly lean or rich.
EGT and CHT don’t have much to do with one another, on an air cooled engine (or any engine for that matter) its not only important to see what thermal energy you are subjecting the engine to, also how much of that energy you are taking away (cooling). For an air cooled engine CHT is depending on airspeed, outside air temperature power and mixture setting. For the same EGT, while increasing airspeed (cooling) the CHT will decrease. So no, EGT does not mimic CHT. Of course you can assume what the CHT would be under the current conditions and with the current EGT. But EGT and CHT are not linked. Without CHT gauge, the only way to operate the engine within limits is following the POH power settings, speeds and leaning schedule. There are aircraft flying around just fine without a CHT and EGT gauge installed.
In a C152 You basically always climb at full throttle, at around 75kt - 80kt, so that the air cooled engine doesn’t overheat.
You start leaning the mixture above around 3000ft. Almost no C152 has a EGT or CHT gauge, even if it’s there it’s probably not working, so you just do it based on the RPM. There are different schools but a “good enough” rule is to just pull the mixture to around the point you reach maximum RPM and it starts to fall again.
Climb performance higher than a few thousand feet will be very poor. The airplane is generally underpowered + the engine looses power even more the higher you go.
That advice is engine specific and does not apply to the C152. Best economy mixture in the C152 is peak EGT.
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I guess you are right, although for climb you should stay away from peak EGT and fly with a rich mixture. Point remains that the EGT value is of little importance, you are looking for the peak EGT and then adjust as (if) required.
Oh yeah, completely agree.
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In my club‘s 172N we have a CHT gauge which has a scale with actual values in Centigrades, the EGT gauge only has a scale with I think a difference of 25F per line. It doesn‘t have a definite value, you can‘t read the temperature from it. But it has an orange pointer that can be set to where you read the peak and so you can easily set your power/economy with the mixture rich or lean of peak.
The EGT gauge is also useful to quickly recognize any carb icing during approach with the throttle near idle. If the EGT rises the carb builds ice and you need to pull the carb heater. EGT will drop immediately.
As mentioned the CHT is critical as you will damage your cylinders if the metal becomes too hot, but a short moment is enough to ruin your engine. The problem is that the CHT is being measured on the outside of the cylinders while the EGT is taken directly from the gas. We always avoid peak EGT, we don‘t even search for it and our engine hasn‘t had any bigger problems yet. But there is simply no really safe way to go by instruments in a C172, only common sense.
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MSFS has nothing about leaning in the lessons. Why are they in 8000 feet? The 172 likes 3000 feet much better. And I can teach this lesson first. And 8000 after… its too much for a newbee😊
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