Snowbird accident 😢

[AirFrame]

I don’t care how high performance your propeller driven GA aircraft is. It doesn’t have a lot of airspeed to begin with, and it loses airspeed a lot faster than it will lose altitude.

Best glide, then think. Please don’t pitch up after an engine failure.

On climb-out, i'm travelling at 2x my best glide speed. I can't get to best glide without climbing more. If I drop the nose, I will never slow to best glide speed.

[Crossthreaded]

Old aircraft that is too large a fleet to retire… maybe some modern engines could be retrofitted in for reliability?

[airway]

Bang on. Pitching up immediately after an EFATO is counter intuitive to most GA pilots. It’s amazing how much “jam” some high performance singles can potentially have in built up in kinetic energy that can then be traded for altitude.

Having time to slow down and work the issue through thoughtfully happens to be a beneficial byproduct.

TPC

I don’t care how high performance your propeller driven GA aircraft is. It doesn’t have a lot of airspeed to begin with, and it loses airspeed a lot faster than it will lose altitude.

Best glide, then think. Please don’t pitch up after an engine failure.

What?

Are you advocating that the guy or gal cruising at 300 knots should just maintain their present altitude until reaching best glide speed and not trade that kinetic energy for altitude?!?

If you are at cruising altitude at an airspeed higher than your best glide speed in a single engine airplane (or drift down speed in a twin), and you have an engine failure, the general recommendation is to maintain altitude until you reach best glide or drift down speed, then nose down to maintain it.

If you are already clear of obstacles, what's the point in climbing? I doubt climbing will stretch the glide, because your airspeed will be lower in the climb compared to just maintaining altitude until you get to your best glide speed. Maybe it would give you more time in the air for decision making?


I can see climbing with an EFATO if you are going much faster than your best glide speed though. Jet or no jet.







.

[pelmet]

I don’t care how high performance your propeller driven GA aircraft is. It doesn’t have a lot of airspeed to begin with, and it loses airspeed a lot faster than it will lose altitude.

Best glide, then think. Please don’t pitch up after an engine failure.

What?

Are you advocating that the guy or gal cruising at 300 knots should just maintain their present altitude until reaching best glide speed and not trade that kinetic energy for altitude?!?

If you are at cruising altitude at an airspeed higher than your best glide speed in a single engine airplane (or drift down speed in a twin), and you have an engine failure, the general recommendation is to maintain altitude until you reach best glide or drift down speed, then nose down to maintain it.

If you are already clear of obstacles, what's the point in climbing? I doubt climbing will stretch the glide, because your airspeed will be lower in the climb compared to just maintaining altitude until you get to your best glide speed. Maybe it would give you more time in the air for decision making?

It is an interesting question. Probably best for the wind tunnel and computers. Assuming the desired place to land is straight off the nose.....if two exact aircraft are flying in formation wingtip to wingtip and both lose their engine at the same time, with all other things being equal.......one climbs and gains altitude until attaining the best glide speed while the other one maintains altitude until attaining best glide speed. The aircraft that climbed will have more altitude but will be farther away that the one that maintained altitude. Who glides further.

[digits_]

The one going straight will lose a lot of speed due to drag, the one climbing will lose speed due to the g forces while changing direction.
The one going straight will limit themselves to fields straight ahead, while the one climbing will have a better view and could easily reach terrain anywhere around its current location. Definitely interesting.

[goldeneagle]

It is an interesting question. Probably best for the wind tunnel and computers.

Dont need a computer and wind tunnel for this question, it's fairly strait forward and has an answer achieved with just a little bit of calculus, and if you are not handy with calculus we can come up with an intuitive description of what happens. We look at the two aircraft as being in a high drag state (operating faster than best glide) and in an optimum drag state (operating at best glide). We also know that drag is a function of velocity squared, ie doubling the speed does not double the drag, it goes up by a factor of 4.

If the aircraft has a very small delta between starting velocity and best glide, it wont make much difference, which is the case for your typical GA aircraft. But lets consider the high performance, or even extreme performance case where the aircraft begins at a velocity 4x that of the best glide speed.

In the strait ahead scenario, the aircraft simply bleeds off kinetic energy strait ahead, the rate at which that energy is shedding is a function of drag, ie, velocity squared all the way from point A to point B. There is no increase in potential energy along the way, ie, it does not climb, it simply sheds kinetic energy along the way.

Now look at the case of the aircraft doing the zoom climb. During the zoom climb it will shed the same amount of kinetic energy as the first aircraft, ending up at the top of the zoom with a given amount of kinetic energy, but also with a whole bunch of potential energy. From there it will trade potential energy for kinetic energy at best glide speed. Because of the lower optimum glide speed, for each meter moved forward, this aircraft will use up less of it's stored energy than the one operating at a much higher speed, this is simply the V squared factor in the drag equation,and if you want to get pendantic about it, the air density factor in the drag equation is slightly lower in this scenario as well.

You can do all the fancy math (I did this math back in the days when I was in school on this subject), it involves a significant amount of calculus because velocities are not constant and air density is not constant, but in the end you will find as aircraft 2 arrives at point B, it will have significantly more energy than aircraft 1, and that energy will be in the form of potential energy, ie altitude. It will take longer to get there, but it will be significantly higher when it does.

But the mistake a lot of folks are making in this thread, they are considering the point of engine failure as the start point of the calculation, that is wrong. The start point of the calculation must begin at the point the pilot recognizes the failure, and begins to react. In your typical light GA aircraft, if there was any excess kinetic energy at the point of failure, it's likely already burned off at the point of recognition, the delta is just not that great. But with a high performance aircraft operating at 2 or 3 times best glide speed at the point of failure, there will be LOTS of excess kinetic energy available, and the best way to save it up for use later, is to convert it to altitude and decelerate the aircraft into a state that burns it off more efficiently.

For perspective, there is another scenario that boils down to the exact same math in terms of conservation of energy. You are short of gas, do you push the throttle in to 'get there faster', or do you pull the throttle back, fly at best range speed, take longer to get there but burn less gas in the process ? In an airplane, gas and altitude are the same thing, potential energy, just stored differently.

[photofly]

Quicker way to explain it:

energy used is the integral of drag x distance. Since the energy is fixed, decreasing drag increases distance. In this case speed can be decreased (to get to minimum-drag airspeed) by storing the energy as gravitational potential energy with close to 100% efficiency, so there is no disadvantage to zooming up.

The best way to climb would be in a ballistic arc: a sharp pull-up followed by a zero-g climb. Induced drag would be zero during the climb. The initial pitch of the climb should be chosen so that the airspeed is exactly on target when the vertical velocity reaches zero.

The height you gain in a zoom climb is (per Denker) 9 feet per knot of speed lost, per hundred knots.

Example 1: in slowing from 130 to 70 you should gain approximately 9 x 60 x 1 = 540 feet.
Example 2: in slowing from 90 to 70 you should gain approximately 9 x 20 x 0.8 = 144 feet.

[Bede]

Quicker way to explain it:

energy used is the integral of drag x distance. Since the energy is fixed, decreasing drag increases distance. In this case speed can be decreased (to get to minimum-drag airspeed) by storing the energy as gravitational potential energy with close to 100% efficiency, so there is no disadvantage to zooming up.

The best way to climb would be in a ballistic arc: a sharp pull-up followed by a zero-g climb. Induced drag would be zero during the climb. The initial pitch of the climb should be chosen so that the airspeed is exactly on target when the vertical velocity reaches zero.

The height you gain in a zoom climb is (per Denker) 9 feet per knot of speed lost, per hundred knots.

Example 1: in slowing from 130 to 70 you should gain approximately 9 x 60 x 1 = 540 feet.
Example 2: in slowing from 90 to 70 you should gain approximately 9 x 20 x 0.8 = 144 feet.

You are correct, but I'm not sure about the stated efficiency approaching unity. Have you ever tried replicating Denker's 9'/kt/100 kts? That's theoretically correct but in a high drag (ie SE Cessna), I think you only get about 50% if I recall. (Remember power is idle.)

[photofly]

Quicker way to explain it:

energy used is the integral of drag x distance. Since the energy is fixed, decreasing drag increases distance. In this case speed can be decreased (to get to minimum-drag airspeed) by storing the energy as gravitational potential energy with close to 100% efficiency, so there is no disadvantage to zooming up.

The best way to climb would be in a ballistic arc: a sharp pull-up followed by a zero-g climb. Induced drag would be zero during the climb. The initial pitch of the climb should be chosen so that the airspeed is exactly on target when the vertical velocity reaches zero.

The height you gain in a zoom climb is (per Denker) 9 feet per knot of speed lost, per hundred knots.

Example 1: in slowing from 130 to 70 you should gain approximately 9 x 60 x 1 = 540 feet.
Example 2: in slowing from 90 to 70 you should gain approximately 9 x 20 x 0.8 = 144 feet.

You are correct, but I'm not sure about the stated efficiency approaching unity. Have you ever tried replicating Denker's 9'/kt/100 kts? That's theoretically correct but in a high drag (ie SE Cessna),

You still lose energy from drag, while you're zooming up. So consider the altitude gain as a bonus over what you would otherwise have lost; if your lack of power means you're descending, you still continue to lose that amount of height during the zoom, before adding the extra. Consider that in example 1 you'd expect to have 540 more feet in altitude than you would have after the same period without zooming up. That might only be 340' net gain because during the same period you would have lost 200 without zooming.

The faster you zoom, the quicker you can stash that energy away. If you can reduce your induced drag to zero (zero g ballistic arc) then you'll lose only energy due to parasite drag. But you were losing that anyway.

I think you only get about 50% if I recall. (Remember power is idle.

Were you weightless during the zoom?

[Bede]

No I didn't even get to 20 degrees before I lost all my speed.

You are correct about everything though.

[photofly]

I am reminded that in theory there is no difference between theory and practice….

[photofly]

I am reminded that in theory there is no difference between theory and practice

[pelmet]

I get lost in the complicated explanations from the super smart people. Who can glide farther, the pull up guy or the bleed off guy?

[rookiepilot]

I get lost in the complicated explanations from the super smart people. Who can glide farther, the pull up guy or the bleed off guy?

Its a pretty obvious answer for any PPL student.

[photofly]

I get lost in the complicated explanations from the super smart people. Who can glide farther, the pull up guy or the bleed off guy?

The pull-up guy. But it won’t make much of a difference unless you’re going really fast.

BTW that’s what air racers do if they have a power failure, and they’re doing 300kts+ at something like 100’ agl, aren’t they? Somewhere there’s a video of a Redbull air race pilot doing exactly that. Couldn’t find the video on YouTube, but I’ve seen it somewhere.

[pelmet]

I get lost in the complicated explanations from the super smart people. Who can glide farther, the pull up guy or the bleed off guy?

Its a pretty obvious answer for any PPL student.

But I am an ATPL, so it is not obvious. Lost my PPL student status many years ago. Forgotten a lot since then. Maybe more than some learned.

[pelmet]

I get lost in the complicated explanations from the super smart people. Who can glide farther, the pull up guy or the bleed off guy?

The pull-up guy. But it won’t make much of a difference unless you’re going really fast.

BTW that’s what air racers do if they have a power failure, and they’re doing 300kts+ at something like 100’ agl, aren’t they? Somewhere there’s a video of a Redbull air race pilot doing exactly that. Couldn’t find the video on YouTube, but I’ve seen it somewhere.

As compared to two planes at typical higher altitudes, I suspect the pull-up maneuver for the Reno guys has a much bigger benefit of providing added view for finding a place to land versus maintaining altitude and bleeding off speed. In the Reno case, there may be an increased possibility of wanting to decrease range by increasing altitude versus increasing range.

[photofly]

Isn’t there a parallel with an EFATO and a power loss in an air-race nearly at ground level? At higher altitudes, who cares if you zoom, you probably don’t need any extra height.

[rookiepilot]

I get lost in the complicated explanations from the super smart people. Who can glide farther, the pull up guy or the bleed off guy?

Its a pretty obvious answer for any PPL student.

But I am an ATPL, so it is not obvious. Lost my PPL student status many years ago. Forgotten a lot since then. Maybe more than some learned.

It’s about time for my running observations on most MBA’s, CFA’s, in my universe.

[AirFrame]

Isn’t there a parallel with an EFATO and a power loss in an air-race nearly at ground level? At higher altitudes, who cares if you zoom, you probably don’t need any extra height.

Altitude above you and runway behind you are both useless in an engine failure situation. You may not need the extra height, but if you can get it, you might as well use it. You can always bleed it off later if you have too much.

[photofly]

Isn’t there a parallel with an EFATO and a power loss in an air-race nearly at ground level? At higher altitudes, who cares if you zoom, you probably don’t need any extra height.

Altitude above you and runway behind you are both useless in an engine failure situation. You may not need the extra height, but if you can get it, you might as well use it. You can always bleed it off later if you have too much.

You have an engine failure at 11,000 feet agl and you're going to zoom up to 11,500?

[AirFrame]

You have an engine failure at 11,000 feet agl and you're going to zoom up to 11,500?

Yep. Every time. That extra 500' won't mean anything at 11000', but it might mean the world when you get down to 500'.

[goldeneagle]

Quicker way to explain it:

energy used is the integral of drag x distance.

Yes, but now try explain it without using big words or calculus, remember your audience is AvCanada, most of whom have never heard of an integral, never mind understand how to calculate it. Reference below.

I get lost in the complicated explanations from the super smart people. Who can glide farther, the pull up guy or the bleed off guy?

the one who pulls up.

[cncpc]

You have an engine failure at 11,000 feet agl and you're going to zoom up to 11,500?

Yep. Every time. That extra 500' won't mean anything at 11000', but it might mean the world when you get down to 500'.

Exactly.

[pelmet]

Quicker way to explain it:

energy used is the integral of drag x distance.

Yes, but now try explain it without using big words or calculus, remember your audience is AvCanada, most of whom have never heard of an integral, never mind understand how to calculate it. Reference below.

I get lost in the complicated explanations from the super smart people. Who can glide farther, the pull up guy or the bleed off guy?

the one who pulls up.

I hated calculus. It’s for engineers. Common sense will save a lot more pilots lives than doing calculus.

I wonder how many university grads took a course called common sense.

Try 180 turn on the edge of a stall after an engine power loss at low altitude?……little common sense.

Try it at or above a pre-planned height at a reasonable speed with a better margin from a stall and a willingness to abandon the maneuver?…..Depending on circumstances, may be worth a calculated risk.

No passing mark in calculus required there.