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idude
Topic Author
Posts: 8
Joined: Thu Jan 18, 2018 5:06 pm

Maneuvering Speed

Tue May 08, 2018 3:27 pm

Does maneuvering speed of an aircraft mean that you need to reduce your IAS to the aircraft's maneuvering speed before you can change your heading or any change of direction? Let's say your Maneuvering speed is 150 and you're cruising at 180 heading North 0 degrees and you need to change your heading to 100 degrees, does the pilot need to reduce speed to a 150 first before he can change the heading to 100 degrees?
 
LH707330
Posts: 2402
Joined: Fri Jun 15, 2012 11:27 pm

Re: Maneuvering Speed

Tue May 08, 2018 4:51 pm

No. Maneuvering speed is the speed at which you'll stall the aircraft before overstressing it given a full control input. As long as you don't make a full input in your example, you can safely turn the aircraft. One thing to be aware of is that maneuvering speed is dependent on wing load factor, and consequently scales as the square root of IAS. Many manufacturers quote Va at MTOW, so for a lighter weight you need to determine Va by doing Va mtow * sqrt((actual weight)/MTOW). So if your Va is 150 kts at your MTOW of 4 tons, and you're at 2 tons, then your Va would be about 106 KIAS.
 
gtae07
Posts: 81
Joined: Thu Jun 16, 2016 8:41 pm

Re: Maneuvering Speed

Wed May 09, 2018 1:02 am

There's also the misconception that Va means "the speed at which you can do anything with the controls and not hurt the airplane". That is false. It's possible (as AA587 highlighted) to break parts of your airplane with full (and especially alternating) inputs well below Va.

If I'm doing my math right after a couple beers, Maneuvering speed=1g stall speed * sqrt(g limit), at least ignoring any compressibility or Reynolds number effects and assuming aircraft weight and configuration are constant...
 
GalaxyFlyer
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Joined: Fri Jan 01, 2016 4:44 am

Re: Maneuvering Speed

Wed May 09, 2018 2:51 am

Be careful of context, too. Some manuals will refer to minimum maneuvering speeds for different flap configurations, for holding or circling to land. These speeds are relative to Vsref and imply stall margin, not the point where a control input equal to maximum certified G results in a wing stall, hence relief of load prior to structural bending or damage.

GF
 
pikachu
Posts: 165
Joined: Thu Feb 07, 2002 5:58 pm

Re: Maneuvering Speed

Thu May 10, 2018 10:04 am

LH707330 wrote:
No. Maneuvering speed is the speed at which you'll stall the aircraft before overstressing it given a full control input. As long as you don't make a full input in your example, you can safely turn the aircraft. One thing to be aware of is that maneuvering speed is dependent on wing load factor, and consequently scales as the square root of IAS. Many manufacturers quote Va at MTOW, so for a lighter weight you need to determine Va by doing Va mtow * sqrt((actual weight)/MTOW). So if your Va is 150 kts at your MTOW of 4 tons, and you're at 2 tons, then your Va would be about 106 KIAS.


Do you have a reference for the stall statement? Would a full rudder or aileron input cause a stall?
 
GalaxyFlyer
Posts: 6708
Joined: Fri Jan 01, 2016 4:44 am

Re: Maneuvering Speed

Thu May 10, 2018 1:56 pm

There’s the rub. I learned back when dinosaurs roamed that Va only meant any further increase in AoA would stall the wing at the certified maximum G, hence relieving the load ON THE WING. There’s an assumption being made, if the wing can take it, everything else can, I guess. It had nothing to do with tail feathers, engine mounts, etc. it was what we in fighters called corner velocity—the lowest IAS for max G.
 
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Florianopolis
Posts: 343
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Re: Maneuvering Speed

Thu May 10, 2018 4:08 pm

I think the replies all get it, but everyone's saying it differently. Pull back on your controls when you're flying below Maneuvering Speed, and the airplane stalls before the wings rip off. But Va makes no promises about any other parts of the airplane, or for maneuvers in more dimensions. See if this helps: http://code7700.com/v-a.htm

For example, to pass certification, you only have to be able to swing the rudder all the way to one side, let the airplane stabilize in a yaw, and then recenter the rudder, without the tail ripping off. If you're fully deflected to the right, and then stomp on the left rudder pedal, there is no legal requirement that the airplane's tail not fall off. Manufacturers desiring a reputation for building sturdy airplanes may build it strong enough to do that, but there's no certification requirement.
 
LH707330
Posts: 2402
Joined: Fri Jun 15, 2012 11:27 pm

Re: Maneuvering Speed

Thu May 10, 2018 9:48 pm

pikachu wrote:
LH707330 wrote:
No. Maneuvering speed is the speed at which you'll stall the aircraft before overstressing it given a full control input. As long as you don't make a full input in your example, you can safely turn the aircraft. One thing to be aware of is that maneuvering speed is dependent on wing load factor, and consequently scales as the square root of IAS. Many manufacturers quote Va at MTOW, so for a lighter weight you need to determine Va by doing Va mtow * sqrt((actual weight)/MTOW). So if your Va is 150 kts at your MTOW of 4 tons, and you're at 2 tons, then your Va would be about 106 KIAS.


Do you have a reference for the stall statement? Would a full rudder or aileron input cause a stall?

Yeah, my PPL Guided Flight Discovery book by Jeppesen. If you google "maneuvering speed envelope load factor" and click images, you'll see some good explanations. As the poster after your quote basically said, it's the speed below which the alpha to attain the critical load factor will result in a stall.

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