Tight weight and balance. Hot climates

[agidi]

Dear flying gurus.
Bothering you with your expertise.

I'm running some exercises, and I'm in doubt about WB and the particulars of the field.

For example we will use the trusty c182N
Front 400lbs
Rear 485lbs
Bag 55lbs
Gas 34gal
That puts the dot right on the envelope.

Say you need to fly from an airport at 4700ft at 95F or 35C or hotter
I understand I need to calculate pressure and density altitude , then turn to my POH and see how much runway I need.
Is this correct?

Then I was told the destination airport will be at 6296msl, but cooler.
I will have a short runway so, do not refuel so I can take off and refuel at a lower airport within 40nm.

I like to be in the safe side. Is my procedure correct?
All comments and opinions are appreciated.
Tips and tricks always welcomed.

 

[MAKG1]

The key point is ... don't extrapolate the performance tables in the POH. If it's not on the table, the "safe side" means don't go. Maybe wait until morning when it might be cooler -- or fly at night if the mission allows.

You generally don't need to calculate the density altitude to use the POH tables (temperature is an input), but you do to compare to the service ceiling.

In a 182, there is quite a lot of room between "don't refuel" and "fill'er'up"

It also makes a massive difference whether you're flying over isolated terrain, desert, farms, or high mountains. Some of those require more margin than others. It also matters if your airports are obstructed.

I like to add 50% to the distance to 50 ft, for some margin, as I'm not a perfect pilot (and even if I were, it wouldn't be safe to presume so).

 

[poadeleted20]

34 gallons isn't a lot of gas in a 182. Make sure you're not putting yourself in a box by short-fueling to stay within W&B. Remember that if you start with 34 gallons and don't refuel, you're running on fumes on the way home.

Maybe you get some skinnier friends or maybe you trade for a 206. Or maybe someone doesn't go. And without running the numbers, I'm guessing that with over 500 lb between the back seats and baggage area, you're really pushing the aft cg limit, and that's a limit you don't ever want to push -- far worse than pushing max gross weight.

Also, like MAKG, I add 50% to the book numbers to acoount for wear and tear on the airframe and engine, as well as less-than-perfect pilot technique.

 

[N801BH]

Dear flying gurus.
Bothering you with your expertise.

I'm running some exercises, and I'm in doubt about WB and the particulars of the field.

For example we will use the trusty c182N
Front 400lbs
Rear 485lbs
Bag 55lbs
Gas 34gal
That puts the dot right on the envelope.

Say you need to fly from an airport at 4700ft at 95F or 35C or hotter
I understand I need to calculate pressure and density altitude , then turn to my POH and see how much runway I need.
Is this correct?

Then I was told the destination airport will be at 6296msl, but cooler.
I will have a short runway so, do not refuel so I can take off and refuel at a lower airport within 40nm.

I like to be in the safe side. Is my procedure correct?
All comments and opinions are appreciated.
Tips and tricks always welcomed.

First post...

Welcome to POA...

 

[bluerooster]

I agree with Ron, 34 gallons is not much gas @ 12-14 gph. Also what happens to your CG as you burn fuel?

Depending on the temp at your destination, you may find performace similar. But the temp at the destination would need to be pretty cool.

When departing MVI (7611.2') in Dads STOL equiped 182, The DA was over 10k' and it was quite cool to me, even wearing my flannel. But we didn't have any trouble at all, Although we were considerably lighter loaded than your scenerio, with full tanks.

 

[agidi]

Thanks! all helpful!

 

[comanchepilot]

Say you need to fly from an airport with those numbers at 95F at 4700'?

How about you wait for it to cool off a little? You want to see your performance? Put that weight in the airplane - then go out and take off with no more than 19" of MP - see how you like it. That is a pretty decent simulation of what you will see - only your actual ROC will worse.

 

[agidi]

Say you need to fly from an airport with those numbers at 95F at 4700'?

How about you wait for it to cool off a little? You want to see your performance? Put that weight in the airplane - then go out and take off with no more than 19" of MP - see how you like it. That is a pretty decent simulation of what you will see - only your actual ROC will worse.

Interesting! So i can "simulate" with the MP, if i dont like it, just go stock on the MP again. Nice

The problem here is that some of the places im at dont ever cool off .
A nice cool morning will begin at 76F, @ 4700, and would fly to 6700 @ 72F

thanks!

 

[poadeleted20]

If you do that test, just remember you have that extra power in reserve if it looks close.

 

[kyleb]

Say you need to fly from an airport with those numbers at 95F at 4700'?

How about you wait for it to cool off a little? You want to see your performance? Put that weight in the airplane - then go out and take off with no more than 19" of MP - see how you like it. That is a pretty decent simulation of what you will see - only your actual ROC will worse.

How'd ya pick 19"? That seems a little low, even for 4,700'.

 

[Skylane81E]

Is the N eligible for the fresh pick STC?

 

[flyingcheesehead]

34 gallons isn't a lot of gas in a 182. Make sure you're not putting yourself in a box by short-fueling to stay within W&B. Remember that if you start with 34 gallons and don't refuel, you're running on fumes on the way home.

Yeah. I'd fly no more than 1.5 hours before refueling on that. It's also hard to fuel a 182 to "34 gallons" as the gallons are very close on the stick at that point - Unless you have a totalizer you trust and know to work correctly and you're going to burn down from full fuel.

And without running the numbers, I'm guessing that with over 500 lb between the back seats and baggage area, you're really pushing the aft cg limit, and that's a limit you don't ever want to push -- far worse than pushing max gross weight.

It's really hard to get our 182N out the aft limit. I know that if I'm in the front, with nothing else up there, and max baggage and the rear seat loaded 'til I'm at gross, I'm still within the aft limit. With a lighter pilot or a plane with a farther aft empty CG, maybe.