Am I experiencing airframe icing?

[A2afan]

Trying to fly the aircraft for maximum range.

Altitude 10,000
Exterior temp -2f
Mixture leaned to 44%
Throttle has to me hold to 87% to maintain 2100 rpm.

Plane seems to be holding 75-80 knots indicated

I have never really pushed for long range high altitude flight before, but it seems like it's taking alot of power to barely hold above stall speed

[Lewis - A2A]

The weather will really affect this, also its a 172 so I wouldn't bother going too high if you are going for maximum range in the little GA. For sure watch the winds and plan accordingly really.

thanks,
Lewis

[Hook]

You are unlikely to get airframe icing unless you are in or near clouds, and you can pretty much ignore it unless you're in freezing rain. If that happens your speed will go down and your nose will start pointing higher (increased angle of attack). You have about 10 minutes in freezing rain. If you're not on the ground in 15 minutes you will be in 20.

Trace and light icing is usually not a problem as the ice will dissipate quickly. Just avoid flying in or near clouds when the temperature is below zero. Simply flying in a cloud with sub-zero temperatures does not guarantee ice. If you somehow pick up a significant amount, your speed will start to decrease and your angle of attack will increase.

Hook

[Oracle427]

It isn't taking a lot of power as the engine power is not a direct function of throttle position.

Your throttle should be wide open at that altitude.

Consider how much power you are making with the engine at full throttle and mixture cutoff?

Consider how much power you are making if you open the throttle wise at sea level and lean aggressively to limit fuel flow?

The engine at 10000 ft can probably barely maintain 55% power with wide open throttke and a properly leaned mixture.

Your ranee increases as you go higher, but as Lewis said, you will find that winds are far more important for planning purposes on long flights. All the efficiency in the world doesn't matter if you are flying into a 50 knot headwind instead of a 20 knot headwind by planning for a different and usually lower altitude.

[ilya1502]

@A2afan

What's your prop setup? 2400 or 2700? The 172S and 172R AFMs suggest that you should be able to get the following numbers. But notice that throttle position is never mentioned, because, as Oracle has correctly noticed, power is not a direct function of it. As long as you can maintain these numbers, throttle position is irrelevant. For the conditions you've specified ADAcalc is showing 87 KTAS.

[Oracle427]

So my memory was wrong. You can maintain nearly 80% power at 10,000 ft with the S prop.
Thanks for sharing the perf chart.