Airspeed does not have to go to zero for the plane to stall, and the forward motion of the plane is still driving the propeller. The propeller will continue to turn until the dead engine's resistance to being turned exceeds the tendency of the airspeed to cause it to turn.
Because it's constantly getting more energy from the airstream. Think of it this way:
The prop is efficient at converting rotation to movement through the air, so it's also (unfortunately) efficient at converting movement through the air to rotation. Wind turbines have much bigger blades, of course, but one of them can capture enough energy in a 5–10 knot wind to power a city block (or more), and a 5-knot wind can move a 2,000 ton wooden sailing ship. And even at the stall, the wings are producing enough lift to hold up your 1,000–3,000 lb ++ plane (you don't suddenly drop straight down like a stone).
My Vg is only 65 mph, so don't get so uppity. It is only the 3rd most popular airplane ever produced - C150, behind two others with 65 kt Vg the C172 and PA28.
A very good argument!
Nonsense. Drag is not exponential with the wind speed. It is proportional to the square of the speed. It is more than linear however.
Is there a subtlety I’m missing in your statement? Something that is “proportional to the square” sure sounds exponential to me.
You will have oil pressure to turn the blades to stop the prop position as the plane then needs to be flown very close to stall speed AFTER reaching said position. IOW FIRST you change the prop pitch and THEN you slow the plane down.
I think you might have it wrong here. Most sources advise to slow to best glide speed.
I don't follow. POH best glide speed assumes prop windmilling with prop blades aligned as much as possible into the relative wind. However; to stop the prop I had to slow to almost stall. Once the prop stopped you can increase glide speed somewhat, hopefully, to a new best glide speed. If anybody REALLY wants the answer then test; don't argue. Of course the purpose of many posts is to just argue endlessly.
Unfortunately, credible testing is expensive, time-consuming, and requires a fair degree of skill (both stick-and-rudder and statistical), so when we go up to test in our planes, the results aren't very reliable (and will often be whatever the person set out to find).
All flying might be considered expensive but testing is no more expensive that just flying around. Testing does require thinking and some effort but is not that difficult. You can measure the the true glide ratio for YOUR plane by climbing to a safe altitude in very calm air (early morning over water?) then noting glide CAS and loss of altitude vs. time converting to TAS and doing simple arithmetic. Also stop the prop and the do the same. Then you will know could even be a hero by reporting back with what you found.
You go do that with your airplane. I'm not shutting down my engine in flight unless I have to. What if it decides not to start back up?
Put your money where your mouth is, or just be the pot calling the kettle black.
I’ve done it too. Why would a healthy engine not start back up again? It’s really not all that risky. I did it at 3000 feet right above a runway though.
nonsense.
The pros will develop a test plan in advance that requires multiple flights on different days, hire a test pilot to fly them, add monitoring instrumentation to ensure that even the test pilot isn't deviating too far from the specs, then repeat the test on multiple days under different conditions before they're confident coming to a conclusion.
Or option 3, post a link to an actual scientific research report, like I did earlier. There may well have been other scientific studies about stopped, feathered, and windmilling props since NACA did theirs in the 1930s, and they might contradict the earlier report, so people are welcome to find and post them to continue the discussion.
Not exactly, because they also tested a free-turning prop against one that was turning the engine. According to that study, a free-spinning prop (unclutched from the engine, which we can't do in our planes) produced only about 60% as much drag. It's difficult to be draw overly-precise conclusions, because the windmilling will also cause the prop to turn more slowly (thus reducing its own induced drag), but it's fair to conclude that about 40% of the drag comes from the work of turning the engine, and the rest comes from the prop itself.
My perfectly healthy engine didn't start one day after a fuel stop because the starter failed. I can think of a few others.
it wasn't perfectly healthy then was it?
I stand corrected.
The "engine" was perfectly healthy. It was the starter that failed. The engine was running fine and would have continued running until it ran out of fuel... had I not shut it down.it wasn't perfectly healthy then was it?
My rule for flying is the same as the one I taught my kids about life: don't go looking for trouble, because it can find you on its own.
If you are actually that risk adverse, then I recommend that you never leave the ground in an airplane.
You could say the same thing about, say, flying VFR into IMC, as if the only two options were "zero risk" or "unlimited risk". Most of us draw a line somewhere between the two extremes.
I suspect you are ignoring far greater risks than those you mention. Do you fly at night, over water, over trees, over mountains or hills, do you switch fuel tanks in flight, are you ever outside glide range of a runway? If you're honest, you'll say yes to at least one of those, and probably more that I didn't list, that are just as great a risk or more, than shutting down an engine in flight, over a runway at 3000 feet AGL.
Read the thread. It was suggested.
So? There is no practical difference in the scenario I described.One has a primary design to operate without power. That's why it has the word "GLIDER" in its name.