CRJ de/anti ice

Doug Taylor said:
Usually thin "cruciform" tails gain the most ice, like on a Jetstream 32.

But the explanation is "aerodynamics"!

Maybe you should send Aero_Engineer a shout-out!
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someone around here knows, it can't be a complicated answer.
 
CFIse said:
1) You did not misunderstand. No anti/de-ice on the tail.

2) We were told "it doesn't need it and I've never heard of anybody having any problems" - so as to the WHY, you got me. :-)
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Perfect timing, a guy I used to work with who is now a CRJ FO called in, so I asked if he knew, he didn't. Did say he asked in training and no one could really tell him why, other than it's not needed.

he did say he has seen them build ice before, but the stab is so thin it just builds a knife edge type of thing on the LE.

My only thought is that it's such a thin edge maybe moisture can only build on the thin LE where it smacks and can't make the curve around it, make sense?
Like an ice proof static port, you know how they're recessed? (never seen one, just pics..)
 
The Mighty Beech doesn't have de-icing on the vertical stab either. And, as Doug said it had a way of accumulating a pretty good load of ice in a short period of time. I always dread the late fall and early spring for dealing with freezing rain along the "Confederate Front". For those of you not familiar, this is a semi-permanent stationary frontal boundry that forms from the mid-Atlantic to the west. It makes for miserible flying conditions (aforementioned freezing rain) in the Appalachians.
The 1900 is a great performer in the ice, and it's very very rare that you will loose airspeed unless you are either not paying attention, or you blundered into conditions you shouldn't have in the first place.
 
BE19Pilot said:
The Mighty Beech doesn't have de-icing on the vertical stab either. And, as Doug said it had a way of accumulating a pretty good load of ice in a short period of time. I always dread the late fall and early spring for dealing with freezing rain along the "Confederate Front". For those of you not familiar, this is a semi-permanent stationary frontal boundry that forms from the mid-Atlantic to the west. It makes for miserible flying conditions (aforementioned freezing rain) in the Appalachians.
The 1900 is a great performer in the ice, and it's very very rare that you will loose airspeed unless you are either not paying attention, or you blundered into conditions you shouldn't have in the first place.
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Did you ever notice the elevator freezing at higher altitude and becoming jammed? There were several times I noticed this...and pitch control basically had to be done with trim....although at higher speeds...trim is usually only used for pitch control so it didn't pose a super control issue. During descent into warmer air...the elevator would "free up"...and you were back in business.

As far as other controllability issues with the -1900 in ice...none. It was simply superb compared to others in its class.
 
Philip said:
I seem to remember from a systems class I took that the CRJ doesn't have any anti or de-ice on the tail. 2 things, did I misunderstand? Second, why doesn't it?
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I've asked this question for different jets over the years and have never gotten a reason why. I hope we can hear from an engineer/certification specialist on this topic.
 
Here's my off-the-cuff speculative guess (note -- not only am I not an engineer, but I didn't even stay at a Holiday Inn Express last night):

For stability, aircraft are designed with the center of gravity forward of the wing, which is counteracted by a horizontal tail surface which creates DOWNwards lift. I would assume that when ice builds on the horizontal tail, it both reduces the downwards lift and increases the weight on the tail, which would in turn have the effect of increasing the downward pressure. Presumably the ice contributes enough weight (but not too much) to compensate for the loss of downwards lift.

And if you don't buy that, my money's on the monkey. :cool:
 
Interesting that we aren't told the exact reason why there's no ice protection back there, but in our last quarterly bulletin there was a good page worth of information on the "tail plane stall" and recovery procedures from it.

Has there been a case of any of these commercial airliners going down because of tail plane stall?
 
Maybe in part MN, but it does not take a lot of ice buildup to damage the lifting properties of an airfoil.

I was taught that tail stalls are extremely dangerous, I just cna't remember why :o
I suppose it could get ugly if you lose that lift and the nose pitches up uncontrollably.


What is the recovery procedure chris?

also, what does the W&B look like for a CRJ? is it possible it doesn't really need much tail down force?
 
Philip said:
I was taught that tail stalls are extremely dangerous, I just cna't remember why :o
I suppose it could get ugly if you lose that lift and the nose pitches up uncontrollably.

What is the recovery procedure chris?
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I seriously doubt that the weight from ice could provide the same amount of down-force as the aerodynamic forces lost to airfoil modification, especially on larger, fast aircraft like the CRJ. Ice is adds weight, but on an aircraft like a CRJ, the accumulation would be a tiny percentage of its gross weight. Even in small aircraft, ice kills because of its aerodynamic effect, not its weight.

And tail stalls can suck because, as the ice builds, the center of pressure may move aft on the stab/elevator surface. Eventually, it can move past the hinge point and actually cause the elevator to fully deflect. The nose would pitch down, not up. Recovery is initiated by decreasing power and pulling BACK on the yoke, sometimes with incredible force. I attended a NASA presentation and saw a video from their tests - the control force required was over 200 pounds of aft pressure. Feet? On the panel!

Never had one, never want to.
 
Tail stalls are highly dangerous for the reason you just stated about the nose pitching up. It won't The nose will drop just like a wing stall. Think about it. That downforce that the tail creates is behind the CG, hence it creates on up movement on the nose. If you loose that downforce in the back, the nose will drop as the tail comes up. Huh... sounds like a normal stall to me. Well, if you apply "normal" ie. wing stall recovery procedures you are going to enter a world of hurt. The reason that the tail surface has stalled is because the airflow has seperated around it. By pushing the nose down you are going to increase the air seperation around the tail leading into an even deeper stall. Also, adding power won't help as it will also increase the airflow seperation. (You'll have to draw this one out to see what I mean.) So, recovery from a tail stall is pitch up and reduce the power to the minimum amount that will keep you in the air. The problem is there is no why to know if it is a tail stall or a wing stall so you need to think about what got you into the stall. If it was a change of flap position or pitch down go with the tail stall If it was a reduction in power or a pitch up, go with the wing stall. That said, there is some really good info on tailstalls and iceing in the NASA program that is floating around out there.
 
SkyWChris said:
Interesting that we aren't told the exact reason why there's no ice protection back there, but in our last quarterly bulletin there was a good page worth of information on the "tail plane stall" and recovery procedures from it.

Has there been a case of any of these commercial airliners going down because of tail plane stall?
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The Jetstream 31 had several tail plane stalls due to icing on short final. Back in the day, many turboprop carriers would wait until 400' or so to select landing flaps. With ice on the tail...and the airflow altered over the stab, the critical AOA of the tail was exceeded and the airplane would nose dive into the ground. Supposedly would occur very fast.

Recovery was to pull back hard on the elevator...reselect approach flaps...and add power.

The FAA issued a bulletin...can't remember it's entire contents...but I seem to remember that in icing conditions there was a minimum speed to fly. Can't remember if flap position was limited as well.
 
B767Driver said:
The Jetstream 31 had several tail plane stalls due to icing on short final. Back in the day, many turboprop carriers would wait until 400' or so to select landing flaps. With ice on the tail...and the airflow altered over the stab, the critical AOA of the tail was exceeded and the airplane would nose dive into the ground. Supposedly would occur very fast.

Recovery was to pull back hard on the elevator...reselect approach flaps...and add power.

The FAA issued a bulletin...can't remember it's entire contents...but I seem to remember that in icing conditions there was a minimum speed to fly. Can't remember if flap position was limited as well.
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come to think of it, wasn't there an L1011 that crashed after holding for an extended period of time in icing due to something similar?
Damn my crappy memory :mad:
 
Philip said:
I've come across that one in my search, maybe, but I could swear it was an L1011. Still searching.
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Man, what is it about the L1011? Twice ground crew have been run over and killed.
 
Thanks for this thread... reminded me I need to complete my winter ops CBT tonight!

When I was on the Saab, we learned a lot about tailplane icing stalls. In fact, NASA pilots came out to talk to our pilots over a few days about tailplane icing, and we got DVDs talking in detail about tailplane ice and the recovery procedures. The Saab was very suceptible to tailplane icing, it seemed. Never experienced it myself, but I do have a couple horror stories about severe ice. Like one late night in Dayton, Ohio flying a LOC only to mins in severe clear ice and severe turbulence. Actually got a hug from a pax on that one. Won't even tell you how much ice was on the airframe.

Although I never experienced a tailplane stall, I have a friend who did. She was flying a freight Lear 25D into MDW one early morning when one of the tailplane boots failed. They had a tailplane stall, and broke out of the clouds in a snowstorm nose down "seeing only trains from the yards." Luckily she realized what type of stall it was, and was able to land safely.

On the CRJ, if I can remember correctly it doesn't have stab ice protection due to the shape of the airfoil, and it's thickness. Bombardier decided that the stab was just not suceptible to ice, so it wasn't worth the complexity of installing the anti-ice equipment for the stab. Takes a lot of air to heat up there.

In the ERJ, we have anti-ice on the horizontal stab. Interesting about this airplane though, is that we don't touch the anti-ice except for takeoff and ground operations. In flight, it is completely automatic. We have ice detection sensors up by the pitot tubes on the nose, and on the tips of the engine fan sections. If those detectors get ice, the anti-ice turns on, and you get an EICAS message saying "anti-ice on" or something to that effect.
 
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