Time, Fuel, Distance to climb chart

[skateosiris]

Hi I was wondering If anyone can help me with the Time, Fuel, Distance to climb chart for the C172?

So you first calculate the pressure altitude for your cruise altitude and the field elevation. Then say if you get a pressure altitude of 2300 for airport elevation and 4200 for cruise elevation, do you just use the 2000 and 4000 on the chart because thats what its closest to?
If the distance is say 12 to my first point on the map to where I am climbing to, how would I find the time it takes as well as the fuel used for the climb and enroute fuel from the airport to the first map point. I am having some trouble with it, if anyone could explain it for the 172, Time, Fuel, Distance to climb chart that would be much appreciated.


I have another question about the Cruise Performance Chart.

Say the temperature is 5 degrees celcius, would I still use the information under the heading of "standard temperature"?

Because I noticed three headings, "20 degrees below standard temp", "standard temp", and "20 degrees above standard".

Thanks

 

[BrewMaster]

Hi I was wondering If anyone can help me with the Time, Fuel, Distance to climb chart for the C172?

So you first calculate the pressure altitude for your cruise altitude and the field elevation. Then say if you get a pressure altitude of 2300 for airport elevation and 4200 for cruise elevation, do you just use the 2000 and 4000 on the chart because thats what its closest to?
If the distance is say 12 to my first point on the map to where I am climbing to, how would I find the time it takes as well as the fuel used for the climb and enroute fuel from the airport to the first map point. I am having some trouble with it, if anyone could explain it for the 172, Time, Fuel, Distance to climb chart that would be much appreciated.


I have another question about the Cruise Performance Chart.

Say the temperature is 5 degrees celcius, would I still use the information under the heading of "standard temperature"?

Because I noticed three headings, "20 degrees below standard temp", "standard temp", and "20 degrees above standard".

Thanks

Why are you cruising at 4200?

 

[shdw]

Why are you cruising at 4200?

He is likely at 4000 with a pressure altitude of 4200.

 

[African_Swallow]

In most cases, these performance charts allow for linear interpolation of the data they do not specifically indicate. If you really want to pick the fly from the pepper, then do that. I'd wager to say many folks will "air on the side of caution" and plan with the next higher number on the performance chart (i.e., if current temps are standard +10, then use the +20 numbers; since the figures are for performance 10 deg higher than actual, you would have added a slight safety buffer in your calculations).

Be sure to read any footnotes associated with each chart, such as "add 10% ground roll for each increase in XX..." or specific conditions such as "zero wind, propeller windmilling, etc."

-A.S.

 

[skateosiris]

Just one more thing, Kind of unrelated but what do you do if you have two magnetic variations along your route, how do you choose which variation to use?

 

[Stone Cold]

Just one more thing, Kind of unrelated but what do you do if you have two magnetic variations along your route, how do you choose which variation to use?

I understand you are wanting to be accurate, but how closely can you hold heading? I think the difference between a +13 and +14 variation will be negligible. I always taught if covering long distances, to split the difference. If you are only going through one change, just use whatever one you start off with.

For accuracy, you can always split the two mag var's and use that in your calculations. I would love to see somebody who can hold a 1/2 degree heading difference, though...

 

[African_Swallow]

Just one more thing, Kind of unrelated but what do you do if you have two magnetic variations along your route, how do you choose which variation to use?

Yeah, you'd rarely be traversing more than 2 or 3 isogonic lines for a typical cross-country flight in a trainer. I plan for only whole number variations. I just plan the variation until my next checkpoint in within the area the new variation. More power to you if you can hold 1/2 degree, like skate' said!

-A.S.

 

[shdw]

I understand you are wanting to be accurate, but how closely can you hold heading? I think the difference between a +13 and +14 variation will be negligible. I always taught if covering long distances, to split the difference. If you are only going through one change, just use whatever one you start off with.

For accuracy, you can always split the two mag var's and use that in your calculations. I would love to see somebody who can hold a 1/2 degree heading difference, though...

Just to give a different teaching style, I have my students change each time they cross over a new line. At the college that seemed to make the examiners smile, sure you probably won't hold it but if it makes your PPL brief shorter why not right?

 

[minitour]

Just one more thing, Kind of unrelated but what do you do if you have two magnetic variations along your route, how do you choose which variation to use?

Which ever one is right when you look out the window and see yourself over your checkpoint.

-mini