Vertical Stabilizers: Why No Anti-ice Protection?

msw

msw

Well-Known Member
Can someone explain why a lot of jet and turbo-prop aircraft aircraft do not have anti-ice protection on the vertical stabilizer, particularly those with T-tails? Obviously, it is because the Vertical Stab on these aircraft are not prone to collecting ice, but my question is WHY is this so?
 
msw said:
Can someone explain why a lot of jet and turbo-prop aircraft aircraft do not have anti-ice protection on the vertical stabilizer, particularly those with T-tails? Obviously, it is because the Vertical Stab on these aircraft are not prone to collecting ice, but my question is WHY is this so?
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I will abstain from giving you a technical answer (I'm not well-versed on this), but will state from experience that the vertical stabs on the jets I've flown *ARE* prone to icing: it just doesn't necessarily adversely affect handling. Anecdotally, I recall Bombardier flying around with a mold of "ram's horn" icing on its stabs and concluding that anti-ice was not necessary.
 
msw said:
Can someone explain why a lot of jet and turbo-prop aircraft aircraft do not have anti-ice protection on the vertical stabilizer, particularly those with T-tails? Obviously, it is because the Vertical Stab on these aircraft are not prone to collecting ice, but my question is WHY is this so?
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I think C150J gave you the best answer. I'll also add that many of the bigger jet aircraft don't even have horizontal stab ice protection. Between a thick airfoil and fully-movable stab, it just doesn't need it.
 
Yeah, I've asked this question before, and the usual response was something akin to "Because flight testing has shown it didn't need it." So you guys are saying that the vertical stab might in fact get iced up, but because icing there did not adversely affect handling, no de-ice/anti-ice provision for the vert stab was necessary? Can anyone chime in with a more aerodynamically/technical answer to this question?
 
In fact, according to urban legend, the 757 and 767 won't even produce airfoil icing and Boeing was going to leave the system off. But of course the FAA thought otherwise. Probably the best decision anyway.

We have nothing on the tail at all, just the leading edges. And I don't even think it's the full leading edge of the wing.
 
Doug Taylor said:
In fact, according to urban legend, the 757 and 767 won't even produce airfoil icing and Boeing was going to leave the system off. But of course the FAA thought otherwise. Probably the best decision anyway.

We have nothing on the tail at all, just the leading edges. And I don't even think it's the full leading edge of the wing.
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I think just the 3 outboard slats. I haven't ever touched the button, except for that whole flameout bulletin thing below FL220.
 
Doug Taylor said:
In fact, according to urban legend, the 757 and 767 won't even produce airfoil icing and Boeing was going to leave the system off. But of course the FAA thought otherwise. Probably the best decision anyway.
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...yeah, right...that's seriously impressive if it's true. If. :)

Something funny about pressure and phase diagrams I'm sure.
 
Tangentially, I was recently surprised to learn that activating TAI causes the stick shaker criteria on another kind of Booing (but I would also bet on the 756) to become more conservative for the remainder of the flight, even after it's turned off. The assumption is that the wing has icing if they're using anti-ice.

Sure, it's not practical knowledge that you should ever have to consider, and it should have no bearing on a decision to use anti-ice, but SYSTEMS! :)
 
Minuteman said:
Tangentially, I was recently surprised to learn that activating TAI causes the stick shaker criteria on another kind of Booing (but I would also bet on the 756) to become more conservative for the remainder of the flight, even after it's turned off. The assumption is that the wing has icing if they're using anti-ice.

Sure, it's not practical knowledge that you should ever have to consider, and it should have no bearing on a decision to use anti-ice, but SYSTEMS! :)
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I don't think so on the 75/76, but I could be wrong. If it does, it doesn't indicate that there's an additive (the ERJ did, however). The wings/tail really don't have a problem with ice; the issue on this airplane is engine icing.
 
knot4u said:
they're not producing lift?
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Sure they are, just not against gravity. Well... Hopefully not in a Boeing. Errr... A Big Boeing that's not a Biplane....

That's how control surfaces work. Why do you think you see VGs installed on vertical stabs?
 
In a big jet that has other yaw control devices (spoilers etc), how much rudder do you normally use? Engine out yaw in cruise state is not really all that great. The only time I have needed a "ton"of rudder was a V1 cut..and, well, you better not have ice on it then.

I've got a feeling that a 75/6 would get along fine without any rudder power at all... Heck in the q we only have to hyd. Sources powering it, (elevator has 3) so they obviously arn't that worried about it

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TwoTwoLeft said:
That's how control surfaces work. Why do you think you see VGs installed on vertical stabs?
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To prevent boundry layer seperation... like a golfball.

Many times the vg you se on jets is only to control airflow, and seperation. The area on say a 737 between the elevator and rudder can create and substantial area of high pressure in some configurations, partially due to flow convergence. By controlling the flow they are able to increase efficiency greatly. As the ship has grown there may be other reasons...

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flyingbum said:
What about the threat of a tail stall?
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I'm not queried about my vert stab stalling..

Tail stall refers to the elevator, which is protected often, or tested not to need it. The whole flying tail thingmakes me think it's not a problem though

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