spinning

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mcrit
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Re: spinning

Post by mcrit »

AuxBatOn wrote:Past the PPL, sure. It teaches the student to fly the airplane in its whole envelope and gives him 1 more thing that he can use in case shit hit the fan.

Here's a good example on a succesful one:
For most light trainers there is no part of the envelope that allows the pilot to turn back to the runway if the engine dies below ~1000 AGL. The 172 has a best glide of ~65 KIAS and a climbs out around 75 KIAS. There is no energy to zoom, the gear is down and welded, and the prop doesn't fx. Your best bet for survivial if you lose the engine on T/O is to hit the softest thing in front of you.

As for how to spin a 172, cgzro had it best. When you hear the stall warning go come back fully on the yoke and put in the rudder. It will spin, but it won't stay in past 3-4 rotations.
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AuxBatOn
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Re: spinning

Post by AuxBatOn »

mcrit wrote:
For most light trainers there is no part of the envelope that allows the pilot to turn back to the runway if the engine dies below ~1000 AGL. The 172 has a best glide of ~65 KIAS and a climbs out around 75 KIAS. There is no energy to zoom, the gear is down and welded, and the prop doesn't fx. Your best bet for survivial if you lose the engine on T/O is to hit the softest thing in front of you.
As stated in a subsequent post, I have done it well below 1000' and landed succesfully. I'll take that over a field any day.
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AEROBAT
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Re: spinning

Post by AEROBAT »

A spin is a autorotation induced by yaw coupling, Auto meaning "self". If it comes out on it's own once control inputs are stopped full autorotation did not develop. In a 172 in utility C of G I doubt the wing stays stalled enough due to the foreward C of G envelope.
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SkySailor
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Re: spinning

Post by SkySailor »

While working on my Commercial completion, I also had to deal with the 172's lack of desire to spin. I found it ironic that a student pilot had to spend more effort and education trying to spin it as opposed to recovering it. Perhaps this is a compliment to the fine engineers at Cessna. What started out as a lesson in spin recognition and recovery, always seemed to wind up being a demo in spiral dive recognition and recovery. It could get irritating after a while.

I suppose I found it irritating because during my Private, training was done on a Piper Tomahawk. When you were ready to spin, that great little trainer would take you on a magic carpet ride!!! No trying to figure out spin entry on that one. Piper, you built a bang-on little trainer.
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Re: spinning

Post by AEROBAT »

The Traumahawk got a bad rap because it would actually spin and lock in.
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AuxBatOn
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Re: spinning

Post by AuxBatOn »

mcrit wrote: For most light trainers there is no part of the envelope that allows the pilot to turn back to the runway if the engine dies below ~1000 AGL. The 172 has a best glide of ~65 KIAS and a climbs out around 75 KIAS. There is no energy to zoom, the gear is down and welded, and the prop doesn't fx. Your best bet for survivial if you lose the engine on T/O is to hit the softest thing in front of you.
Allright, I ran some numbers, based on my old Cessna 150M manual. I assumed that the indicated airspeeds were TAS, that the aircraft was a MTOW and wind constant with altitude. Altitude lost in the turn assumed to be 200', everything flown at Vx (best rate).

With no wind on take off, and a 3000' runway, there is a very narrow window in which you could make it, with very little margin, between 210' and 250' AAE. Really, it's unrealistic in those conditions.

However, we add 10 kts headwind in take off and that window expands from 210' AAE to infinity, meaning that from that point, the climb angle exceeds the glide angle.

Now, for a 5000' runway and no wind, the window is now between 210' and 1300' AAE. Outside that, you are eighter too low to make the turn or you can't glide back after the turn.

So, with as little as a 10 kts headwind, you can be reasonably sure you can make it back.
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Big Pistons Forever
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Re: spinning

Post by Big Pistons Forever »

mcrit wrote:
AuxBatOn wrote:Past the PPL, sure. It teaches the student to fly the airplane in its whole envelope and gives him 1 more thing that he can use in case shit hit the fan.

Here's a good example on a succesful one:
For most light trainers there is no part of the envelope that allows the pilot to turn back to the runway if the engine dies below ~1000 AGL. The 172 has a best glide of ~65 KIAS and a climbs out around 75 KIAS. There is no energy to zoom, the gear is down and welded, and the prop doesn't fx. Your best bet for survivial if you lose the engine on T/O is to hit the softest thing in front of you.

As for how to spin a 172, cgzro had it best. When you hear the stall warning go come back fully on the yoke and put in the rudder. It will spin, but it won't stay in past 3-4 rotations.
Spin entries in every aircraft I have flown work better if yaw is induced first and then the stick is brought briskly back to induce the stall.
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Re: spinning

Post by Big Pistons Forever »

AEROBAT wrote:A spin is a autorotation induced by yaw coupling, Auto meaning "self". If it comes out on it's own once control inputs are stopped full autorotation did not develop. In a 172 in utility C of G I doubt the wing stays stalled enough due to the foreward C of G envelope.
A fully developed spin occurs when the aircraft has settled into a stable rate of rotation and has a stable pitch attitude. Most airplanes take at least two rotation for this to occur. For the purpose of PPL and CPL training the distinction is meaningless as the point of the exercise is to first recognize the developing spin condition and recover and failing that, then if you are do inadvertantly let the aircraft continue into a spin again recognize and recover. If you let the aircraft achieve the fully developed spin condition than you are IMO missing the point of the exercise.

If you truely want to fully learn all aspects of how to enter and recover from spins than you should IMO do it as part of an aerobatic training program in an aerobatic airplane
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Re: spinning

Post by 767 »

mcrit wrote: Your best bet for survivial if you lose the engine on T/O is to hit the softest thing in front of you.
+1. :smt040

During EFTO at low altitude, there is no time to figure out about what energy state the airplane will turn back safely. I dont understand what this has to do with flying experience. :roll: When your way up there, there is plenty of time to decide where you want to land.
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Re: spinning

Post by hz2p »

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Re: spinning

Post by Big Pistons Forever »

hz2p wrote:
For most light trainers there is no part of the envelope that allows the pilot to turn back to the runway if the engine dies below ~1000 AGL
Completely wrong. I have personally demonstrated the "impossible possible turn" - see Dave Roger's paper - many times, for real in a C172 with the throttle pulled at 500 feet AGL.

http://jeremy.zawodny.com/flying/turnback.pdf

Please don't confuse what the AIRCRAFT is aerodynamically capable, with what a particular, fumbling pilot randomly decides to sub-optimally do on any given day.

The ignorance here is astounding.

You would likely be surprised to learn what are the important factors in the turnback. But then again, no one here needs to learn anything because they know it all.

I dont understand what this has to do with flying experience
I really pity your students.


As far as spin entries go ... I guess none of the geniuses here have considered the rate of airspeed decrease?
Why do find it necessary to be so rude ?

Since this thread is about spinning perhaps if anyone wants to further discuss the turn back manoever, they should start a new thread
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MichaelP
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Re: spinning

Post by MichaelP »

Four seat aircraft have to be controllable in a stall situation fully loaded and at a full aft CG position.
For this reason alone they are at a fwd CG position that is not helpful for spin entry in the utility category.

A fine example of this is the TB10 which is not easy to land power off with one or two persons on board. It runs out of pitch control and so they put a short nose leg on it!
For this aeroplane to be 'safe' at the stall with 454lbs on the back seat pitch authority has to be enough to stall and recover of course at the aft CG limit. This means compromising pitch authority when at the fwd limit.

Many aeroplanes are like this, for 182's, 206's, and Senecas as examples it's always advisable to put some weight in the rear when flying one or two up.

A Cessna 172 would spin if you could move the CG back.

A British trainer that the critical Barney might be refering to was the Beagle Pup 150. Provision was made to bolt weights onto the ventral fin for spin training.
In this way the three to four seat Pup 150 could still be spun when two up while without the weights the CG would allow for one or two (lightweight) people in the back.

The proof of the spin is in the airspeed.
If on the second turn the speed is still low and staying there, this is a true spin.
Those that claim that a Cessna 172 properly loaded in the Utility category can do 2 to 3 turns should look at the ASI to confirm this.

Yesterday we did indeed 'spin' the Cessna 172 C GCZN using 1800 RPM on entry and for one left turn.
One turn of this alleged spin is all that needs to be demonstrated for a CPL flight test.
I have done a lot of 'spinning' so to speak in the Cessna 172 and I am obviously not nearly as competent as Barney is or many on this forum because I look at the ASI and I see it increasing as the aeroplane I believe enters a spiral.
Indeed while still holding the control column all the way back and with full rudder applied I found that I could roll the aeroplane out of this 'spin' which is something I would normally do to flatten a true spin.

But, loaded to the aft CG limit the control authority is easily enough to spin the Cessna 172, and in this condition we need to be aware.
The aeroplane will not be as difficult to spin fully loaded and will catch you out very quickly.

Go fly a true spinning aeroplane for at least once in your career.
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AEROBAT
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Re: spinning

Post by AEROBAT »

I am surprised nobody ever brings up the Beggs/Mueller method of spin recovery. It is foolproof for a lot of aerobatic planes. There is no difference if you are inverted or upright.
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Re: spinning

Post by Tango01 »

AEROBAT wrote:I am surprised nobody ever brings up the Beggs/Mueller method of spin recovery. It is foolproof for a lot of aerobatic planes. There is no difference if you are inverted or upright.
That's because its a spin entry thread. Once we settle the entry, we'll start the recovery discussion. :)
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Re: spinning

Post by AEROBAT »

Tango01 wrote:
AEROBAT wrote:I am surprised nobody ever brings up the Beggs/Mueller method of spin recovery. It is foolproof for a lot of aerobatic planes. There is no difference if you are inverted or upright.
That's because its a spin entry thread. Once we settle the entry, we'll start the recovery discussion. :)
Sorry..... :)
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Re: spinning

Post by AuxBatOn »

767 wrote:
+1. :smt040

During EFTO at low altitude, there is no time to figure out about what energy state the airplane will turn back safely. I dont understand what this has to do with flying experience. :roll: When your way up there, there is plenty of time to decide where you want to land.
So, when you fly, there are 2 types of energy: kinetic (speed) and potential (altitude). Since you kinetic energy is pretty much constant in a climb, the only other thing you need to look at to "assess" you energy is your Altitude. Part of your duty as a pilot is to know what your aircraft can do. You know that with a 10 kts headwind in a C-152, you can turn back, and land from theoraticallly 200'. Now, you may not be comfortable doing it at 200', leaving no margin, however give yourself 150' and you can do it comfortably from 350'. So, it's too hard for someone to think, when in the climb "Hmmm, I just passed 350' AAE, I'm good for a turn back"? You really don't trust your students?

Giving yourself "gate" or "criteria" is the way you asses your energy.
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Re: spinning

Post by MichaelP »

the way you asses your energy
Of course if you get it wrong then you make an 'ass' of yourself 8)

This is similar to the loop discussion.
An expert pilot does a superb loop, dead accurate, knows the radius of that loop and then doing that very precise loop with a little margin for error he piles the beautiful example of aerobatic grace into the ground in a spectacular flaming explosion right in front of the appreciative crowd.

Always know that however well you fly your aeroplane you will never fly it that well in an emergency.
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Re: spinning

Post by AuxBatOn »

MichaelP wrote:
the way you asses your energy
Of course if you get it wrong then you make an 'ass' of yourself 8)

This is similar to the loop discussion.
An expert pilot does a superb loop, dead accurate, knows the radius of that loop and then doing that very precise loop with a little margin for error he piles the beautiful example of aerobatic grace into the ground in a spectacular flaming explosion right in front of the appreciative crowd.

Always know that however well you fly your aeroplane you will never fly it that well in an emergency.
Hence the:
AuxBatOn wrote:Now, you may not be comfortable doing it at 200', leaving no margin, however give yourself 150' and you can do it comfortably from 350'.
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Re: spinning

Post by MichaelP »

Regardless... Before you look at the altimeter ensure the speed is there to do it!

Personally I lower the nose first and assess the situation and I might be at 350 feet or so, but lower than that when I have fully assessed the situation.

I'd be very very careful with this one. It is nearly always better to crash ahead while under control than risk loss of control turning.
Take the wind into account and remember the Illusions lesson from your training.
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Re: spinning

Post by AuxBatOn »

MichaelP wrote:Regardless... Before you look at the altimeter ensure the speed is there to do it!
If you keep Vx, in my experience with small cessnas, you will be able to make the turn... Safely. If you were climbing at Vx and trimmed for Vx, when the engine quits, the plane will want to maintain Vx.
MichaelP wrote:Personally I lower the nose first and assess the situation and I might be at 350 feet or so, but lower than that when I have fully assessed the situation.
That's why you need to be ready. If you loose power on the climb out, above 350', or whatever you cut off is for that day, you turn back, no questions asked. There is not much time to think and analyse on a take off emergency and pre-tought actions must be taken.
MichaelP wrote: I'd be very very careful with this one. It is nearly always better to crash ahead while under control than risk loss of control turning.
If you keep your speed up to Vx around the corner, you should not have any problem, unless you pull more than 2Gz (That's more than 60 degrees of bank!) Keeping 30-40 degrees bank is normally enough to turn you around efficiently.
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Re: spinning

Post by Shiny Side Up »

AuxBatOn wrote: If you keep Vx, in my experience with small cessnas, you will be able to make the turn... Safely.
Personally I'd like to bring you here and make you eat some words. Being able to make the turn depends on a lot of factors many of which haven't been brought up in this discussion. The first which has was the headwind component. True enough if you got 10+ Knots right off the nose you'll probably be able to make it back. I don't know where you fly out of, but I rarely get such ideal conditions - nine times out of ten if there's wind it will be a cross wind. Do your vector diagram - with any sort of crosswind component it changes your glide considerably. Think fast! Which way do you make your turn? Into the wind or with it?

Density altitude plays a big factor as well, so does the weight of the aircraft. In Alberta I'm usually flying out of places in the 3000'+ field elevation. Unless I'm a combination of lightly loaded (in otherwords by myself with less than a half load of fuel) with a perfect headwind, more than 3000' of runway (easier to make it back to the nearest end) and a relatively cold day, I ain't making that "impossible turn".

Its not an impossible turn, but in most cases its an improbable turn.
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Re: spinning

Post by AuxBatOn »

Shiny Side Up wrote:
AuxBatOn wrote: If you keep Vx, in my experience with small cessnas, you will be able to make the turn... Safely.
Personally I'd like to bring you here and make you eat some words. Being able to make the turn depends on a lot of factors many of which haven't been brought up in this discussion. The first which has was the headwind component. True enough if you got 10+ Knots right off the nose you'll probably be able to make it back. I don't know where you fly out of, but I rarely get such ideal conditions - nine times out of ten if there's wind it will be a cross wind. Do your vector diagram - with any sort of crosswind component it changes your glide considerably. Think fast! Which way do you make your turn? Into the wind or with it?

Density altitude plays a big factor as well, so does the weight of the aircraft. In Alberta I'm usually flying out of places in the 3000'+ field elevation. Unless I'm a combination of lightly loaded (in otherwords by myself with less than a half load of fuel) with a perfect headwind, more than 3000' of runway (easier to make it back to the nearest end) and a relatively cold day, I ain't making that "impossible turn".

Its not an impossible turn, but in most cases its an improbable turn.
I ran the numbers and I'd be more than happy to share the excel spreadsheet that I made. It takes into consideration pressure altitude, temperature, wind component, altitude lost in turn and runway lengh. It calculates the take off roll, climb gradient, descend gradient, landing roll and comes up with a window of opportunity (described in altitude) depending of the factors input by the user and gives you where on the runway you will touch down. Made for C-150M, can be easily changed to any other small single (by changing the tables).

Turning into wind is always your best bet to come back to the field (and the direction of the wind should be well known before take off). It keeps you laterally closer to the runway. Unless you have a parrallel runway you want to land on.

Using this, if we take a 3500' pressure altitude at 20 degrees celcius and no wind, you can make it on a 4000' runway (marginally, I would not try it), and it's easy to make from a 5000' runway up to 400'.
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Re: spinning

Post by Shiny Side Up »

Using this, if we take a 3500' pressure altitude at 20 degrees celcius and no wind, you can make it on a 4000' runway (marginally, I would not try it), and it's easy to make from a 5000' runway up to 400'.
I'll point out that a marginal bet isn't one to risk your life on. I'll also bring up the point that this depends heavily on maintinaing Vx to altitude, and obviously becomes even more "marginal" if you have less than 4000' of runway available.
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Re: spinning

Post by AuxBatOn »

Shiny Side Up wrote:
Using this, if we take a 3500' pressure altitude at 20 degrees celcius and no wind, you can make it on a 4000' runway (marginally, I would not try it), and it's easy to make from a 5000' runway up to 400'.
I'll point out that a marginal bet isn't one to risk your life on. I'll also bring up the point that this depends heavily on maintinaing Vx to altitude, and obviously becomes even more "marginal" if you have less than 4000' of runway available.
That's why you need to know what conditions you are faced with and know how they will affect your decision. Post PPL, I don't think it is unreasonable to expect that from students.

I do not encourage people to push the envelope, but rather find a comfortable envelope in which they could perform it. Saying that it is an "impossible turn" is pure BS. It is possible, but it takes practice and you have to think it through on the ground, before you attempt it in the air.

As far as Vx to altitude, well if you are faster than Vx, you can trade that speed for turning performance or altitude, which in the end, would be almost the same thing (you'd loose a little bit since climbing above Vx is not as efficient, but it'd be pretty darn close).

If you are slower than Vx (but faster or on Vy), you are just climbing steeper, improving your situation. That's why I use Vx and not Vy.

Nonetheless, I think it's at the very least something to discuss and consider. If you are not comfortable with it, nothing forces you to even try it. However, if you consider it, it becomes other option that is available to you in case something goes wrong.
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Re: spinning

Post by Big Pistons Forever »

MichaelP wrote:Regardless... Before you look at the altimeter ensure the speed is there to do it!

Personally I lower the nose first and assess the situation and I might be at 350 feet or so, but lower than that when I have fully assessed the situation.

I'd be very very careful with this one. It is nearly always better to crash ahead while under control than risk loss of control turning.
Take the wind into account and remember the Illusions lesson from your training.
A big plus one.

Auxbaton

It doesn't matter if you can do the turn back at 350 AAE, what matters can every civil PPL student do it everytime. I am positive that every one of my students, on their worst day, could manage a safe landing straight ahead (with a + - 30 deg turn to avoid obstacles) below 1000 AAE and can safely turn back above 1000 AAE, that's why I teach the 1000ft mark as the decision altitude. The accident statistics are pretty clear, the turn back manoever after a real engine failure seems to come out two ways, it is either successfull of there is a big hole full of dead people.

BTW have you ever instructed for the civil PPL ? Instructing for the air force means you are teaching the cream of the crop in a very controlled environment. Regretably these advantages do not exis in civil instructing and so I feel some extra margin has to be allowed for civil instructing.
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