Turn towards live or dead engine?
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Several thoughts -
(a) 5 deg bank - relevant to Vmca rather than any consideration of climb performance. In the absence of any information to the contrary in the POH, one should presume that Vmca was determined with 5 deg into the operating engine
(b) You can turn an aircraft any which way ... provided you can keep min control speed Vmca is VERY bank dependent. If you bank the wrong way, Vmca goes up, significantly .. eg as I recall the B52 goes up something like 30-35 knots for 5 deg into the failed engine.
(c) Either way never get below V2 If Vtoss is not too distant from Vmca then, if conditions replicate Vmca, you risk going over on your back if you turn to the dead engine at Vtoss. Rarely are you given the actual data in a civil POH.
(d) best climb (minimum descent in many light twins at weight and DH) typically is around 2-3 deg into the operating engine and approximates nil sideslip .. this is true of just about any multiengine aircraft. Any other bank angle increases sideslip, drag, and down you go faster .. ergo OEI turns in light twins are a risky business if the level performance is marginal (which it near invariably is ..)
(e) turn into the dead engine CAREFULLY to achieve a tighter turn radius I've given it some thought but it still doesn't make too much sense .. I'm obviously missing some critical point in the suggestion ?
(f) Incr in bank means more drag not from wings to level to a few degrees into the operating engine ... if one wanted to nitpick ..
(a) 5 deg bank - relevant to Vmca rather than any consideration of climb performance. In the absence of any information to the contrary in the POH, one should presume that Vmca was determined with 5 deg into the operating engine
(b) You can turn an aircraft any which way ... provided you can keep min control speed Vmca is VERY bank dependent. If you bank the wrong way, Vmca goes up, significantly .. eg as I recall the B52 goes up something like 30-35 knots for 5 deg into the failed engine.
(c) Either way never get below V2 If Vtoss is not too distant from Vmca then, if conditions replicate Vmca, you risk going over on your back if you turn to the dead engine at Vtoss. Rarely are you given the actual data in a civil POH.
(d) best climb (minimum descent in many light twins at weight and DH) typically is around 2-3 deg into the operating engine and approximates nil sideslip .. this is true of just about any multiengine aircraft. Any other bank angle increases sideslip, drag, and down you go faster .. ergo OEI turns in light twins are a risky business if the level performance is marginal (which it near invariably is ..)
(e) turn into the dead engine CAREFULLY to achieve a tighter turn radius I've given it some thought but it still doesn't make too much sense .. I'm obviously missing some critical point in the suggestion ?
(f) Incr in bank means more drag not from wings to level to a few degrees into the operating engine ... if one wanted to nitpick ..
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Ive flown 60 degree AOB turns in Barons and Duchesses into the dead engine albeit lightly loaded and with 2 hours fuel. You just have to be very careful.
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Gents, be very careful. 
Many people have been killed by a poor understanding of VMCA. Of all the factors that affect VMCA, the angle of bank is quite significant in that it is controlled by the pilot and that relatively small changes in AoB have large and significant effects on the air mininum control speed. I'm not currently flying a Dutchess or Baron but in my current aircraft 5deg AoB towards the dead enging increases VMCA by about 15KIAS and 30deg AoB towards the dead increases it by up to 30-40KIAS!
This is not to say that you can't turn towards the dead engine, it's not the turn that is the problem (typically), it is rolling out from the turn where you either 1. run out of aileron control or 2. stall the down going wing.
Any time I turn towards the dead I check that power on the operating engine is less than max and IAS is high. "Power low, speed high, turning towards the dead". On the average light twin you can't achieve this immediately after take off but can in the cruise.
If I had a choice my preference would be to 1. Maintain flight straight ahead 2. Turn towards the live 3. Turn towards the dead (with low power and excess IAS).
Good on you for asking the question but be careful who you listen to.
Please speak to a good instructor about this issue and get an aerodynamics book that clearly explains asymmetric flight, including VMCA before you attempt this in the aircraft.
Many people have been killed by a poor understanding of VMCA. Of all the factors that affect VMCA, the angle of bank is quite significant in that it is controlled by the pilot and that relatively small changes in AoB have large and significant effects on the air mininum control speed. I'm not currently flying a Dutchess or Baron but in my current aircraft 5deg AoB towards the dead enging increases VMCA by about 15KIAS and 30deg AoB towards the dead increases it by up to 30-40KIAS!
This is not to say that you can't turn towards the dead engine, it's not the turn that is the problem (typically), it is rolling out from the turn where you either 1. run out of aileron control or 2. stall the down going wing.
Any time I turn towards the dead I check that power on the operating engine is less than max and IAS is high. "Power low, speed high, turning towards the dead". On the average light twin you can't achieve this immediately after take off but can in the cruise.
If I had a choice my preference would be to 1. Maintain flight straight ahead 2. Turn towards the live 3. Turn towards the dead (with low power and excess IAS).
Good on you for asking the question but be careful who you listen to.
Please speak to a good instructor about this issue and get an aerodynamics book that clearly explains asymmetric flight, including VMCA before you attempt this in the aircraft.
Quote:
Ive flown 60 degree AOB turns in Barons and Duchesses into the dead engine albeit lightly loaded and with 2 hours fuel. You just have to be very careful.
One would hope that your sixty degree angle of bank was a momentary overbank due to inadvertant loss of control. That can be forgiven. But to deliberately cause the aircraft to reach sixty degrees bank angle on one engine in a multi-engine aircraft to prove it can be done? Not a good idea...
Ive flown 60 degree AOB turns in Barons and Duchesses into the dead engine albeit lightly loaded and with 2 hours fuel. You just have to be very careful.
One would hope that your sixty degree angle of bank was a momentary overbank due to inadvertant loss of control. That can be forgiven. But to deliberately cause the aircraft to reach sixty degrees bank angle on one engine in a multi-engine aircraft to prove it can be done? Not a good idea...
Gotta agree with Ducksarse on this one!
If possible, turn towards the live. You only have to remember your original multi endorsement and how ugly it was trying to roll out of a turn towards the dead to realise a very sick aeroplane is getting close to being uncontrollable in that situation.
Hence, the old tip: "raise the dead". Do otherwise only if unavoidable, and then very carefully (and at your [further] peril)!
Ted
If possible, turn towards the live. You only have to remember your original multi endorsement and how ugly it was trying to roll out of a turn towards the dead to realise a very sick aeroplane is getting close to being uncontrollable in that situation.
Hence, the old tip: "raise the dead". Do otherwise only if unavoidable, and then very carefully (and at your [further] peril)!
Ted
What happens when you approach Vmca?
The aircraft starts to roll and yaw toward the failed engine as you run out of aileron authority.
The initial tendancy is for the aircraft to;
1) Yaw to the failed engine due to asymmetric thrust,
2) Yaw to the failed engine due to asymmetric drag,
3) Roll to the failed engine due to yaw in that direction,
4) Roll to the failed engine due to asymmetric lift (airflow from the live engine over the wing and nacelle),
5) Yaw to the failed engine due to increased drag produced by the downward deflected aileron on that side trying to counter the roll,
6) Slip generating roll and yaw toward the failed engine.
All these effects need control inputs to arrest the undesired changes in attitude happening.
The slower you go (ie. approaching Vmca) the less control effectiveness available, the more deflection required to achieve the same effect and the sooner you reach the physical limit of deflection.
Vmca is a control speed.
Now if you increase the yaw toward the failed engine you are going to reach the limit of aileron travel earlier to stop the aircraft rolling into the turn (which it already wants to do). More control deflection means more drag and any increase in drag is going to be detrimental to performance.
If you need proof of this just get your instructor to simulate an EFATO and do a circuit turning each way. You may not even maintain height turning towards the dead engine. It doesn't matter if the props are CR or not. There WILL be a noticeable difference.
Addenum,
The critical engine is specified as worst case scenario. It's failure will create the greatest problem and may not be prop direction related. Aztrucks may have CR props, but early models with the hydraulic pump (for gear and flap actuation) only on the left engine makes it a left engine critical aircraft.
Simply speaking, picking up the dead side by 5deg bank and 1/2 a skid ball to the live side is a compromise between using all bank (fully balanced- max rudder) and wings level (not balanced- max aileron). It allows for the best remaining control deflection in comparison with the best drag reduction (basically). It is also the max specified bank allowed in the determination of Vmca (or Vmc as the FAA calls it) as per FAR 23.
The aircraft starts to roll and yaw toward the failed engine as you run out of aileron authority.
The initial tendancy is for the aircraft to;
1) Yaw to the failed engine due to asymmetric thrust,
2) Yaw to the failed engine due to asymmetric drag,
3) Roll to the failed engine due to yaw in that direction,
4) Roll to the failed engine due to asymmetric lift (airflow from the live engine over the wing and nacelle),
5) Yaw to the failed engine due to increased drag produced by the downward deflected aileron on that side trying to counter the roll,
6) Slip generating roll and yaw toward the failed engine.
All these effects need control inputs to arrest the undesired changes in attitude happening.
The slower you go (ie. approaching Vmca) the less control effectiveness available, the more deflection required to achieve the same effect and the sooner you reach the physical limit of deflection.
Vmca is a control speed.
Now if you increase the yaw toward the failed engine you are going to reach the limit of aileron travel earlier to stop the aircraft rolling into the turn (which it already wants to do). More control deflection means more drag and any increase in drag is going to be detrimental to performance.
If you need proof of this just get your instructor to simulate an EFATO and do a circuit turning each way. You may not even maintain height turning towards the dead engine. It doesn't matter if the props are CR or not. There WILL be a noticeable difference.
Addenum,
The critical engine is specified as worst case scenario. It's failure will create the greatest problem and may not be prop direction related. Aztrucks may have CR props, but early models with the hydraulic pump (for gear and flap actuation) only on the left engine makes it a left engine critical aircraft.
Simply speaking, picking up the dead side by 5deg bank and 1/2 a skid ball to the live side is a compromise between using all bank (fully balanced- max rudder) and wings level (not balanced- max aileron). It allows for the best remaining control deflection in comparison with the best drag reduction (basically). It is also the max specified bank allowed in the determination of Vmca (or Vmc as the FAA calls it) as per FAR 23.
Agreed, however everyone doing their initial multi is given a demo (albeit simulated) of the symptoms, effects and recovery when approaching this condition.
The statement was made to illustrate the difference in performance with direction of turn with regard to the failed engine.
Similarly to stalling, you know about it, but the aim is not to actually let the aircraft get to this point outside of a training scenario. Even more so with Vmca.
The statement was made to illustrate the difference in performance with direction of turn with regard to the failed engine.
Similarly to stalling, you know about it, but the aim is not to actually let the aircraft get to this point outside of a training scenario. Even more so with Vmca.
I've just been reading the myths that are prevalent about this on the internet and just stunned. "Make it happen" is on the right track in this thread. Go back to basic physics. The aim is to keep the nose of the aeroplane pointing into the airflow. One engine fails--it creates immediate Yaw. So you immediately stop the yaw with rudder. Now if you are wings level and there is no yaw, the rudder is generating an unresolved lateral force. Let's say the left-engine failed. The aeroplane tries to yaw left, you pressed the right rudder to stop the left yaw. The rudder is now generating a force at the tail out to the left. So the aeroplane will be pulled to the left by the rudder. This is a side-slip...no good. How do you counter a side slip? By banking to the right so that you null out the lateral force of the rudder with an equal and opposite component of force from the weight vector. Once you have the aeroplane going in a straight line (right rudder in, and right bank) you secure the dead engine, clean up the draggy things and then trim the aeroplane so that it will fly like this indefinitely. Only then should you make any significant turns. Obviously since you are banked towards the right you have less scope to bank further that way, but that doesn't mean you can't turn that way. You can bank slight more to the left as well. Turn whichever way the situation demands.
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It always comes down to know your aeroplane.
I.e VMCA in a smellymole is a non event, as it stalls long before you lose directional control.
System Critical, aerodynamic critical...or both...know your aeroplane!
Interesting on what we are taught tho. A comment above refers to getting the aeroplance cleaned up for SE climb. From what I understand, BPPP teaches that if you are not cleaned up, then you act as a single and close both throttles.
I.e VMCA in a smellymole is a non event, as it stalls long before you lose directional control.
System Critical, aerodynamic critical...or both...know your aeroplane!
Interesting on what we are taught tho. A comment above refers to getting the aeroplance cleaned up for SE climb. From what I understand, BPPP teaches that if you are not cleaned up, then you act as a single and close both throttles.
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There does not seem to be any new light twin models (only new variants) other than this since the 80's.
Can this single engine climb and ceiling be confirmed by anyone?
Or are they a bit unrealistic like the older light twins?
With both engines turning, the Tecnam 2006T delivers 1,140 fpm climb. Shutting down power on one side reduces that to 212 fpm, and single engine service ceiling is 7000 feet.
In one country I worked, every year the aircraft had to do a flight test at max weight. With twins that included engine out (fully shut down and feathered) time to climb 500 ft.
We did this at the end of all other tests so we were lighter and possibly forgot to load a few sandbags anyway. Not one flight were single engine climb figures close, most flights we actually timed the decent of 500 ft from the ceiling height.
Can this single engine climb and ceiling be confirmed by anyone?
Or are they a bit unrealistic like the older light twins?
With both engines turning, the Tecnam 2006T delivers 1,140 fpm climb. Shutting down power on one side reduces that to 212 fpm, and single engine service ceiling is 7000 feet.
In one country I worked, every year the aircraft had to do a flight test at max weight. With twins that included engine out (fully shut down and feathered) time to climb 500 ft.
We did this at the end of all other tests so we were lighter and possibly forgot to load a few sandbags anyway. Not one flight were single engine climb figures close, most flights we actually timed the decent of 500 ft from the ceiling height.
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To answer your question directly without throwing a million hypotheticals at you or show you how much I know..
..You'd be better off turning towards the live as you're reducing Vmca by doing so (control benefit).
Performance-wise there are gains to be had by turning towards live as this is why the zero slip method includes banking to live.
..You'd be better off turning towards the live as you're reducing Vmca by doing so (control benefit).
Performance-wise there are gains to be had by turning towards live as this is why the zero slip method includes banking to live.
