Snowbird accident 😢

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TeePeeCreeper
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Re: Snowbird accident 😢

Post by TeePeeCreeper »

‘Bob’ wrote: Wed Aug 10, 2022 8:58 am
TeePeeCreeper wrote: Sun Aug 07, 2022 6:57 pm
AirFrame wrote: Sun Aug 07, 2022 7:43 amWhile you're decelerating, you'll have some more brain cycles free while your brain wraps around the situation and you get down to your best glide speed.
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?!?
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fleet16b
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Re: Snowbird accident 😢

Post by fleet16b »

pelmet wrote: Wed Aug 10, 2022 9:14 am
fleet16b wrote: Wed Aug 10, 2022 5:59 am Well once again the Team has been grounded .
Incidents are getting more and more frequent .
At some point reality needs to kick in here.
The Snowbirds have had a great run but it can’t last forever flying these antiques.
National pride and stubbornness is going to get more people killed .
I wonder if they should get the team flying Hawks.
I don’t think that is an option as the Hawks I believe are leased not owned by the RCAF
And second I don’t think the RCAF has any intention on ever upgrading the Snowbirds
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Re: Snowbird accident 😢

Post by pelmet »

fleet16b wrote: Wed Aug 10, 2022 11:13 am
pelmet wrote: Wed Aug 10, 2022 9:14 am
fleet16b wrote: Wed Aug 10, 2022 5:59 am Well once again the Team has been grounded .
Incidents are getting more and more frequent .
At some point reality needs to kick in here.
The Snowbirds have had a great run but it can’t last forever flying these antiques.
National pride and stubbornness is going to get more people killed .
I wonder if they should get the team flying Hawks.
I don’t think that is an option as the Hawks I believe are leased not owned by the RCAF
And second I don’t think the RCAF has any intention on ever upgrading the Snowbirds
Interesting. I suppose they could purchase those ones or other ones if there was an intention of an upgrade.
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Re: Snowbird accident 😢

Post by fleet16b »

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Re: Snowbird accident 😢

Post by AstroPants »

pelmet wrote: Thu Aug 11, 2022 2:47 am
fleet16b wrote: Wed Aug 10, 2022 11:13 am
pelmet wrote: Wed Aug 10, 2022 9:14 am

I wonder if they should get the team flying Hawks.
I don’t think that is an option as the Hawks I believe are leased not owned by the RCAF
And second I don’t think the RCAF has any intention on ever upgrading the Snowbirds
Interesting. I suppose they could purchase those ones or other ones if there was an intention of an upgrade.
"Those ones" are well past their best before date (which may actually make them ideal for purchase in how procurement seems to go, I guess). They've already had to restructure the flight training (Wings phase on T-6 now instead of Hawk) to drag the jets over the contract finish line. I think the plan was to wait and see what is selected for the future FLIT program and make a decision then. Lots of money being put into the Tutors, which I believe includes a new seat (thankfully).
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Re: Snowbird accident 😢

Post by AirFrame »

‘Bob’ wrote: Wed Aug 10, 2022 8:58 amI 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.
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Re: Snowbird accident 😢

Post by Crossthreaded »

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

Post by airway »

TeePeeCreeper wrote: Wed Aug 10, 2022 10:08 am
‘Bob’ wrote: Wed Aug 10, 2022 8:58 am
TeePeeCreeper wrote: Sun Aug 07, 2022 6:57 pm

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.







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Re: Snowbird accident 😢

Post by pelmet »

airway wrote: Mon Aug 22, 2022 12:19 pm
TeePeeCreeper wrote: Wed Aug 10, 2022 10:08 am
‘Bob’ wrote: Wed Aug 10, 2022 8:58 am

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.
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Re: Snowbird accident 😢

Post by 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.
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Re: Snowbird accident 😢

Post by goldeneagle »

pelmet wrote: Mon Aug 22, 2022 4:10 pm 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.
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Re: Snowbird accident 😢

Post by 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.
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Re: Snowbird accident 😢

Post by Bede »

photofly wrote: Fri Aug 26, 2022 11:14 am 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.)
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Re: Snowbird accident 😢

Post by photofly »

Bede wrote: Fri Aug 26, 2022 12:06 pm
photofly wrote: Fri Aug 26, 2022 11:14 am 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?
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Re: Snowbird accident 😢

Post by Bede »

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

You are correct about everything though.
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Re: Snowbird accident 😢

Post by photofly »

I am reminded that in theory there is no difference between theory and practice….
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Re: Snowbird accident 😢

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I am reminded that in theory there is no difference between theory and practice :-)
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Re: Snowbird accident 😢

Post by 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?
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Re: Snowbird accident 😢

Post by rookiepilot »

pelmet wrote: Fri Aug 26, 2022 5:15 pm 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.
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Re: Snowbird accident 😢

Post by photofly »

pelmet wrote: Fri Aug 26, 2022 5:15 pm 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.
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