Factors affecting Vmc
08-10-2007, 02:15 PM
#2
Gets Weekends Off
Joined APC: Jan 2006
Position: Spartan
Posts: 3,652
Let's see if I can remember from my ME training days...
Worst case is heavy, critical engine failed(usually the left), gear up, aft CG, good engine operating at high power...may be forgetting a thing or two.
Worst case is heavy, critical engine failed(usually the left), gear up, aft CG, good engine operating at high power...may be forgetting a thing or two.
08-10-2007, 02:51 PM
#3
On Reserve
Joined APC: May 2007
Posts: 17
Increases your VMC speed...........Landing gear up, unfavorable c.g., flaps up, takeoff power set, windmilling prop, banking more than 5 degrees into the operative engine, hitting VMC out of ground effect.
Decreases your VMC speed..........Gear down, forward stable c.g., flaps down, banking equal or less than 5 degrees into the operative engine, low power, feathered prop, hitting VMC in ground effect.
Simple way to remember, if its more stable, VMC will be lower, less stable, VMC is higher.........................
Decreases your VMC speed..........Gear down, forward stable c.g., flaps down, banking equal or less than 5 degrees into the operative engine, low power, feathered prop, hitting VMC in ground effect.
Simple way to remember, if its more stable, VMC will be lower, less stable, VMC is higher.........................
08-10-2007, 05:51 PM
#4
Line Holder
Joined APC: Apr 2006
Posts: 88
I would like to mention something about the flaps. I have NO authoritive basis for this, so take it as is (I'm sure someone will be along to correct me anyways 
). I think those depend on the plane whether they help or hurt Vmc. I have heard that on the Seminole, they help by making it more stable. On the Baron, they hurt Vmc because they blanket the airflow to the rudder. Again, I have no real evidence of that, so if someone could give a bit more insight, I will have learned something new today.
). I think those depend on the plane whether they help or hurt Vmc. I have heard that on the Seminole, they help by making it more stable. On the Baron, they hurt Vmc because they blanket the airflow to the rudder. Again, I have no real evidence of that, so if someone could give a bit more insight, I will have learned something new today.
08-10-2007, 07:00 PM
#5
Gets Weekends Off
Joined APC: Mar 2006
Position: KCCO
Posts: 767
The memory aid I used was 4 engine, 4 congifuration, 2 weight, 2 pilot input...
4 engine:
- Critical engine inop
- Prop on critical engine windmilling (unless autofeather installed)
- Takeoff or max avail. power
- Sea Level
4 Configuration
- Gear up
- Flaps in T/O position
- Cowl flaps in T/O position
- Max sea level gross weight
2 Weight
- Max sea level gross weight
- Most unfavorable CG (usually aft)
2 Pilot Input
- Airplane airborne and ground effect negligible
- Up to 5 degrees of bank towards operative engine
Other members explain how these change Vcm, but this memory aid helped me. Good luck.
4 engine:
- Critical engine inop
- Prop on critical engine windmilling (unless autofeather installed)
- Takeoff or max avail. power
- Sea Level
4 Configuration
- Gear up
- Flaps in T/O position
- Cowl flaps in T/O position
- Max sea level gross weight
2 Weight
- Max sea level gross weight
- Most unfavorable CG (usually aft)
2 Pilot Input
- Airplane airborne and ground effect negligible
- Up to 5 degrees of bank towards operative engine
Other members explain how these change Vcm, but this memory aid helped me. Good luck.
08-12-2007, 07:22 PM
#7
Gets Weekends Off
Joined APC: May 2007
Position: JS32 FO
Posts: 848
Originally Posted by etflies
The memory aid I used was 4 engine, 4 congifuration, 2 weight, 2 pilot input...
4 engine:
- Critical engine inop
- Prop on critical engine windmilling (unless autofeather installed)
- Takeoff or max avail. power
- Seal Level
4 Configuration
- Gear up
- Flaps in T/O position
- Cowl flaps in T/O position
- Max seal level gross weight
2 Weight
- Max sea level gross weight
- Most unfavorable CG (usually aft)
2 Pilot Input
- Airplane airborn and ground effect negligible
- Up to 5 degrees of bank towards operative engine
Other members explain how these change Vcm, but this memory aid helped me. Good luck.
4 engine:
- Critical engine inop
- Prop on critical engine windmilling (unless autofeather installed)
- Takeoff or max avail. power
- Seal Level
4 Configuration
- Gear up
- Flaps in T/O position
- Cowl flaps in T/O position
- Max seal level gross weight
2 Weight
- Max sea level gross weight
- Most unfavorable CG (usually aft)
2 Pilot Input
- Airplane airborn and ground effect negligible
- Up to 5 degrees of bank towards operative engine
Other members explain how these change Vcm, but this memory aid helped me. Good luck.
08-12-2007, 07:48 PM
#8
Gets Weekends Off
Joined APC: Jan 2006
Posts: 762
Originally Posted by etflies
The memory aid I used was 4 engine, 4 congifuration, 2 weight, 2 pilot input...
4 engine:
- Critical engine inop
- Prop on critical engine windmilling (unless autofeather installed)
- Takeoff or max avail. power
- Seal Level
4 Configuration
- Gear up
- Flaps in T/O position
- Cowl flaps in T/O position
- Max seal level gross weight
2 Weight
- Max sea level gross weight
- Most unfavorable CG (usually aft)
2 Pilot Input
- Airplane airborn and ground effect negligible
- Up to 5 degrees of bank towards operative engine
Other members explain how these change Vcm, but this memory aid helped me. Good luck.
4 engine:
- Critical engine inop
- Prop on critical engine windmilling (unless autofeather installed)
- Takeoff or max avail. power
- Seal Level
4 Configuration
- Gear up
- Flaps in T/O position
- Cowl flaps in T/O position
- Max seal level gross weight
2 Weight
- Max sea level gross weight
- Most unfavorable CG (usually aft)
2 Pilot Input
- Airplane airborn and ground effect negligible
- Up to 5 degrees of bank towards operative engine
Other members explain how these change Vcm, but this memory aid helped me. Good luck.
Also Vmc decreases as weight increases. Single Engine performance decreases with an increase of weight, but Vmc actually decreases.
08-14-2007, 09:25 AM
#9
Line Holder
Joined APC: Aug 2007
Position: CFII
Posts: 33
Originally Posted by XcalibeR
I would like to mention something about the flaps. I have NO authoritive basis for this, so take it as is (I'm sure someone will be along to correct me anyways ). I think those depend on the plane whether they help or hurt Vmc. I have heard that on the Seminole, they help by making it more stable. On the Baron, they hurt Vmc because they blanket the airflow to the rudder. Again, I have no real evidence of that, so if someone could give a bit more insight, I will have learned something new today.
). I think those depend on the plane whether they help or hurt Vmc. I have heard that on the Seminole, they help by making it more stable. On the Baron, they hurt Vmc because they blanket the airflow to the rudder. Again, I have no real evidence of that, so if someone could give a bit more insight, I will have learned something new today.
08-14-2007, 10:36 AM
#10
On a beach with no ocean
Joined APC: Aug 2006
Position: Unmanned
Posts: 166
Vmc
Since I'm currently stuck in Las Vegas at ATP's CFI’s school and I’ve been over this more times than I can count. All I can add is this,
SMACFUM- The conditions that affect VMC,
Sea level pressure-increases VMC
Max power on the operating engine-Increases VMC
Aft legal C.G-Increases VMC
Critical engine Wind milling-Increases VMC
Flaps/gear down-decreases VMC
Up to 5 degrees of bank into operating engine-Decreases VMC
Most unfavorable weight-A lighter airplane has a higher VMC than heavier airplane
YUM-YUM
SMACFUM- The conditions that affect VMC,
Sea level pressure-increases VMC
Max power on the operating engine-Increases VMC
Aft legal C.G-Increases VMC
Critical engine Wind milling-Increases VMC
Flaps/gear down-decreases VMC
Up to 5 degrees of bank into operating engine-Decreases VMC
Most unfavorable weight-A lighter airplane has a higher VMC than heavier airplane
YUM-YUM
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