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In most GA prop airplanes, take-off is executed with full throttle and high rpm. The usual reasoning is that this way, we leave the first few hundred feet, where failures are most severe, behind as fast as possible.

Isn't this like driving a car, seeing ice/playing kids/any other hazard, and speed up to leave the danger behind? In other words: Shouldn't we be most careful and conservative near the ground, with as little stress to the engine as feasible?

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    $\begingroup$ I used to actually do that in my plane when I used it to commute to work at an airport with a 10,000 ft runway. Because I had 2 miles of runway ahead, plus all kinds of land-able terrain beyond, and I was flying alone with lots of reserve power, I adopted my own version of "flex thrust" and would just set climb power, about 24" of MP, and takeoff like that. It's not a common practice outside of transport world however, and I would use normal takeoff power when departing regular GA airports. On normal takeoffs I reduce power to climb settings at about 2-300 feet or so. $\endgroup$
    – John K
    Feb 10 at 0:20
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Aviation is an exercise in mitigating risks. There's usually more than one hazard at any given time.

So, yes, running your engine at full power might increase risk of engine failure versus a lower power setting.

However, taking off at lower power settings increases risks in other areas. For instance ...

  • ... you have to reach rotation speed before you go flying, regardless of how long it takes to get to that speed. At lower power settings, you hit rotate speed closer to the departure end of the runway, so if you have an issue of some sort, you're more likely to run off the end of the runway.
  • ... at lower power settings, you gain altitude slower and at a lower climb angle, so you have fewer options if the engine does give way.
  • ... taking off with low power might hide the fact that you have an engine problem and can't make full power. You might not know your engine can't make full power until it's too late. (I've heard this was possibly factor in the recent B17 crash)

So, when you add all of the risks together, the industry has figured out that it's generally safer to take off at full power or close to it. That being said, a lot of operators do use lower power takeoffs to reduce wear and tear over time. Those that do this, however, only do it when it's relatively low-risk (long and dry runway, low takeoff weight, shallow obstacle clearance requirements, no difficult climb restrictions to make, etc).

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It should come as no surprise that flying an airplane is not like driving a car. When driving a car, you can come to a complete stop and nothing exciting will happen. You cannot do this in an airplane; coming to a complete stop is either the beginning or the end of a great deal of excitement.

Flying near the ground in any circumstance is a hazard. As you say, the goal is to get away from the ground as quickly as possible. This should not be "stress to the engine", engines are designed and maintained to support the full throttle takeoff.

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    $\begingroup$ You bring up a good point in your last sentence - unlike most (not all*) car engines, aircraft engines will quite happily sit at a relatively high RPM for long periods of time. They are designed specifically for the task, and indeed can support fairly high periods of full throttle. *As an example, the old VW aircooled engine had a cruise speed the same as its top speed. I doubt it's much of a coincedence that they shared a lot in common with the design of your average GA engine $\endgroup$
    – Dan
    Feb 9 at 20:42
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Because Runways Are Short (relatively speaking)

The simple answer comes down to the fact that you only have so much space to take off so getting off the ground as fast as possible is the most practical and most safe option.

Aircraft will fly when the wings generate sufficient lift to overcome the weight of the aircraft, this happens when there is enough airflow over the wing which in turns broadly happens with sufficient air speed.

Lets examine a counter case for a minute. Say you did a partial power takeoff, you only apply some throttle (enough to overcome drag) and start your roll slowly, you will be out of runway long before you reach your takeoff speed. That being said with sufficiently long runways you would be able to take off with less than full power.

Aircraft engines have no issue spooling up and running at full power for takeoff and climb out, as a matter of fact aircraft engines are generally better at running at high power settings for long periods of time since that is exactly what they are designed for.

Takeoffs also include a "decision speed" which should take full throttle breaking distance into account so you should be able to abort a takeoff if there is insufficient power or speed.


But, also, the POH says so...

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  • $\begingroup$ Not to mention that even if the runway is long enough to get off the ground in ground effect, your climb performance might not be good enough to clear the trees at the end of the airfield... so you may need high RPM anyway. And if the engine will quit at that power I'd rather that happen at 20kts on the ground than Vx at 50ft. $\endgroup$
    – Ben
    Feb 9 at 21:47
  • $\begingroup$ There are some exceptions, e.g. the turbo Arrow I fly will overboost at sea level with full throttle so we don’t go above 38" or so of MP. $\endgroup$
    – JScarry
    Feb 9 at 23:31

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