Thanks for this Henning. What are the numbers referring to-- G forces?
Lost engine training
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That is correct. It's been a while, but best of my recollection was 50*G force has something akin to an LD-50 drug dosage where it kills 50% of the time & 75 G was 100% lethal. Again IIRC, the primary cause of failure was the aorta tearing off. Also, survival does not mean undamaged/crippled.
I was sorta hoping you were going to say that they referred to airspeed-- since that seems more controllable, somehow. Although controlling the airspeed in turn controls the G forces, right? Kind of?
Sac Arrow
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Maybe I'm stupid or missing something, but could someone please explain to me why a stopped prop (not a feathered) has less drag than a windmilling one? That makes no sense to me.
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It takes energy to rotate the engine. Also, an airfoil is more efficient at converting between motion / energy when it is "lifting". When the prop is stopped it's just flat plate drag.
Most definitely! Every bit of speed you reduce, you get to take the square of the kinetic energy away!!! This is why it is sooo critical to be absolutely comfortable and in command of the very ragged bottom of the speed envelope of your plane. In a REAL short field situation, a field shorter than you can stop in, the difference between a 1.2 & 1.3 Vso approach can be significant to the damages and injuries sustained, and if it was short enough I'd be looking to bottom out at 1.01 Vso and let the gear and wings absorb it. Main thing is to keep control aslong as you can.
Get out your Multi Engine Pilots Guide and read the section where they talk about "flat plate effect". It comes mostly from the drag imposed by rotating the engine. There is no free energy within the boundaries of our universe, rotating that engine takes energy and that energy comes from airspeed/altitude when you are in glide mode.
Another point on that, you're thinking is backwards, having those numbers as Gs rather than Kts is much more comforting as they provide a much larger threshold of survivable opportunity that way.
TMetzinger
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G forces refer to acceleration. What that means in this context is how quickly or slowly you dissipate that speed. The less speed you start with,and the slower you bleed it off, the better. If you have to lose it quickly, make the airplane take the punishment, like ripping the gear off.
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So getting comfortable there is the same as getting comfortable anywhere else with regard to flying-- go there and do it over and over, right? Until you're not longer afraid of it?
Thanks Tim...
TMetzinger
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Yes, ma'am!
Later on, you might consider an acrobatic intro flight and maybe some spin training. Both are not as scary in reality as you might think.
For now, practice that slow flight, especially turning slow flight, so you get comfy feeling the plane at low levels of energy.
Funny... I've been given that exact advice before. This is on my list of things to do!
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Bob Gardner
There is a useful graph on page 12-3 of the Airplane Flying Handbook. You can look at it on the FAA home page if you do not have a copy available.
Bob Gardner
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You get flat plate drag from a windmilling prop...it goes away when the prop stops. I suggest that you check out Figure 12-3 in the Airplane Flying Handbook (on page 12-3, in fact).
Bob
Did you really need to use question marks?
denverpilot
Tied Down
This is a theme in Mick Wilson's "How to Crash an Airplane and Survive" too...
If you're gonna crash, hit the softest thing you can find. And hit it with the wings because it'll come through the plexiglass in front of you.
His real world example for mountain pilots was a stand of Aspen trees vs. a stand of any sort of Pine trees.
Aspens have lots of tiny branches which will bend, break, and dissipate energy as the aircraft descends through them. The trunks aren't as big and they're softer wood so they'll break. deceleration will last longer and you'll have a better chance of survival.
The Pines on the other hand will just reach up and smite thee, if the stand is thick. Thinner is better and try to aim between two trees to rip the wings off.
Rock is the worst. Bang, done.
Bushes below treeline are manna from heaven. Land in them as if you were making a normal landing.
Etc etc etc. Aim for the softest "stuff".
If you're gonna crash, hit the softest thing you can find. And hit it with the wings because it'll come through the plexiglass in front of you.
His real world example for mountain pilots was a stand of Aspen trees vs. a stand of any sort of Pine trees.
Aspens have lots of tiny branches which will bend, break, and dissipate energy as the aircraft descends through them. The trunks aren't as big and they're softer wood so they'll break. deceleration will last longer and you'll have a better chance of survival.
The Pines on the other hand will just reach up and smite thee, if the stand is thick. Thinner is better and try to aim between two trees to rip the wings off.
Rock is the worst. Bang, done.
Bushes below treeline are manna from heaven. Land in them as if you were making a normal landing.
Etc etc etc. Aim for the softest "stuff".
Momentary (ok, not so momentary) lapse of confidence with regard to MCA. This is something I will get. Luckily I have a lesson coming up...
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TMetzinger
Final Approach
MCA always made me uncomfortable, too. The real purpose of the MCA drillls is to get you to the point where you know what it feels like and that you'll take appropriate action to reduce the angle of attack unless you're in the one place where you really want to feel that sensation - 3 inches above touchdown.
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It says it's so, but it doesn't say why it's so.
However, I found the answer in one of my fluid dynamics textbooks after consulting with one of my former profs. The simplified explanation is that a stagnation layer builds on a stationary flat plat (prop blade) which acts as a fairing. A parallel wind loading (windmilling prop) will not allow the stagnation layer to develop, removing the aerodynamic fairing effect.