Crj-200 Stall Characteristics
 

This is for all you CRJ-200 experts:

A friend of mine told me that when he was in SIM practicing departure stalls, there was one characteristic he encountered during the recovery portion of the maneuver. He was taught that once the SIM hits the shaker, he was to apply power and call for "Set Max. Thrust". However, shorty after power application, he noticed the thing wanting to pitch down regardless of what he did to hold the pitch attitude constant. And at some point he hit the pusher!

My question is this: is this a normal departure stall characteristic for a CRJ or what? How do you suppose to control the pitch down tendecy after the application of power:cool:? What do you recommend or what do you do about such characteristic?

Let's hear from the experts!

my understanding
 

I'm by no means an expert, but here's my understanding.....

Supposedly the pitching down moment is caused by the engines' location in the back of the airplane as opposed to wing mounted ones and where the thrust line is in relation to the body of mass being pushed.

As for getting the pusher, I believe that has to do with the smoothness of getting that nose up and maintaining that pull. If you pull it too hard you put some more loads on those wings or at least make the computer think that and get a pusher as means of protection.

Guys....? chime in.

I'm going to wager a guess and say nobody on this board knows what the stall characteristics of a CRJ (or ERJ, for that matter) are. All we know is what the approach to a stall is like.

We did a "Full Stall" in the sim in DFW, and no joke it took more than 5,000ft to recover.............:confused:

I'm no expert either, but I think you're right. The nose will pitch down with an increase of thrust (especially with max power). The RJ recovers from an incipient stall using only thrust to increase speed as opposed to increased thrust and a low pitch attitude as is the recovery techniques with smaller recips.

When max power is set, the nose will tend to drop and if the controls are not smooth to correct this, the aircraft will end up in a secondary stall as indicated by the stick pusher activation.

Your sim partner should smoothly (and maybe a tad slower)set the thrust to max power. Then smoothly maintain your target attitude.

Also, the perfomance of each simulator differs, some are more sensitive than others. Others need tweaking to bring them closer to reality.

I loved training in the T-37... could stall and spin the crap out of that bird... my favorite was an inverted spin... now that was sporty hanging in the straps...

In the sim world- max thrust and spoilers in while respecting the shaker does the trick in the checkride.. You will hold within 50 ft. (As I recall) The nose up attitude is only a few degrees but within a few seconds you are out of the shaker with a healthy positive trend vector. Then its all about getting the flaps up and getting the thing trimmed again. If you do "yank" and get the pusher you are looking at the bucking bronco which could turn into a 5000' adventure. Hope it helps..

I've done a stall to stick push in the CRJ several times (in the actual aircraft on delivery acceptance test flights). It's really no big deal, and the aircraft recovers quite nicely provided that you have enough room to lower the nose a few degrees and SMOOTHLY apply power. Of course altitude wasn't an issue since we did them at 15,000'.

As mentioned before, the nose down tendancy when initially applying power is due to the engines being mounted above the longitudinal axis of the aircraft. Since the thrust axis is above this line (and above the "center of balance" from nose to tail), the addition of power creates "asymmetrical thrust" above the center of balance (if that makes any sense).

My recommendation on any maneuver is to go through it at a reasonable pace and not rush the recovery. Another good thing to do anytime that you add power from slow speed is thumb the trim for about half a second as you apply power. This is good for both the stall recovery and a go around.

1, because (in the case of a go around), it will disconnect the A/P. (Although pushing TOGA will as well).

And 2 because it gets the aircraft moving in the right direction as you apply power and counteracts that initial nose down tendancy. Once you get moving in the correct direction, then simply thumb it out (odds are you'll need to take out even more than you just put in, or the plane will do a tailstand and fly off like a homesick angel).

The sim is a bit squirrely, but in real life the actual approach to stall, shake and subsequent stick push is a nice smooth and stable approach. The nose drops before you even hit the buffet, and at altitudes where the air is thicker, the push isn't even that abrupt (maybe -.25g? If that?).

Josh your clue to go through at a reasonable pace is right on.....when stalling and spinning the T-37... we use to take a couple of deep breaths.... enjoy the ride and then perform the boldface.

It's a great rule when you're doing anything in an aircraft. With the exception of cabin/pressure hull fires and rapid decompressions at altitudes above FL250, there are very few things that can kill you in an aircraft rapidly... except simultaneous brain farting of both pilots.

yeah from what i have read everyone is right. its hard for me to explain but easy for me to picture,, ya know?? :) when the engines are fired up they are pushing from the back of the plane above the cg. the plane will try and rotate around its cg. and since the engines are above the cg, on the tail, the tail wants to go up, while the nose wants to go down essentially trying to spin the aircraft on its lattitudnal axis. its just the opposite on all boeing aircraft (except the 727). when they stall the nose wants to pitch up and the tail down because the engines are below the cg of the aircraft. could explain it better if i had a whiteboard and a model... hahaha

as far as getting the pusher your sim partner did 1 of 2 things wrong. he either pulled back to fast on the stick, which the plane will recognize as an imminent stall, or went above 7.5 degrees with the shaker engaged.

the best way to do it is get shaker, set max thrust and then hold the nose right at 5 degrees. as the plane gains speed and energy it will take less back pressure to maintain 5 degrees nose up. it can all be done within 50 feet.

the engines on the RJ are ever so slightly tilted so the thrust actually goes back and down, that design is a lot more pronounced on a DC-9 or MD-8X , Im sure that adds to the nose down pitch. The #2 engine on the DC-10 was like that as well, and that had a pretty big tilt to it.

I know they tell you not to trim when doing an approach to stall, but if you partner is having finesse problems, consider the use of trim to keep off the yoke until they get the hang of how the airplane responds.

Maybe someone can find the accident summary, but I can't. I believe one of the ones lost during certification was during stalls. The recovery chute did not deploy if I remember correctly.

Try holding down the AP DISC button. You'll avoid getting the pusher.

I know if you do this on the ground you do get a STALL FAIL caution message. I'm not sure what happens in flight.

The engines do push the nose down on power application. Its a little at first then a whole lot as the engines spool up. The key is proper seating position so you can hold the yoke with your elbows on the arm rests. This helps prevent over controlling. At the shaker DO NOT release back pressure! This is the hard part as most of us learned to release pressure to break a stall. Hold the nose at 7.5 degrees. This takes a fair amount of effort. As the power comes in keep applying back pressure or the nose will drop. Its OK to go back into the shaker. You shouldn't get the pusher unless you are rough on the controls or yank the nose above 10 degrees. Once the nose stops trying to go down watch your altitude and VSI or you will shoot through your altitude. Let the nose go back to about 3 degrees and relax your grip on the yoke to make minor adjustments in the final stage of recovery.

Great advises. One thing though: I am hearing 7.5 degrees and 5 degrees nose up during the recovery portion when the pitch down tendency occurs. The question is, what is the exact number of degrees that you should use?

Again, thanks for great inputs!

I suppose there is no "exact" number. I was taught 7.5 by both Pinnacle and CAE instructors. I did have one instructor demo a recovery where he held the nose at 10 degrees. The shaker will usually start at about 10 degrees - he just held it right there throughout and never got the pusher. I'd say that would be too big a challenge for a new guy though.

Here's my technique as taught by a couple of different instructors and check airmen:

Watch your pitch attitude as you approach the stall. Since you're at flaps 20 and in a 20 degree bank, this takes a decent scan. Try to get the pitch attitude into your scan though. When you get the shaker and roll the wings level, hold the pitch attitude at whatever it was when the shaker activated. As stated by FlyingGuy, lock your elbows on the arm rests and maintain this pitch attitude. I have had no problem just pushing the thrust most of the way up without much finesse and letting the Non Flying Pilot fine tune it. As the thrust comes up, the nose will want to pitch down. Just using your wrists, add back pressure. If you hold the yoke with your elbows locked on the arm rests without adding this backpressure, you won't hold the pitch attitude. Using this technique will cause you to lose no more than 25 feet or so and makes for a nice maneuver.

7.5 works good, try not to exceed 10. If you exceed 10 you will most likely get a secondary shaker. It took me a while to get a feel for the stalls. Try placing your elbows on the armrests and use pressure and small corrections to maintain the slight nose high attitude required for recovery. Thats what worked for me.

The attempt to deep stall the CL-65 during initial certification resulted in a hull-loss and the deaths of some very experienced Bombardier pilots. Roll that beeyotch instead.

Good points.

We 'stall' the airplane every day when we land. Speed is the key. There's a real sweet spot with the CRJ (the 200 more so than 700/900). If you're above ref you'll float down the runway. If you're less than 10 below ref, the airplane stops flying and you'll do a three point landing. There is not much of a margin between ref and stall, especially in strong gusty crosswinds.

Trust me... if you ever do a full stall landing in the CRJ, you'll know it. You aren't stalling the CRJ when you land- in fact, even 10 knots below ref, you probably have another 10 knots before you even get into the area where AOA becomes an issue. You might reduce lift to a point where it's no longer able to maintain a standard descent rate, but you aren't stalling.

No, the 3 point landings in the CRJ come from to much speed, not to little. Pull the power off at 100' instead of 50'.

3 point landings come from poor technique. I have landed a CRJ at both ref +10 and ref-10, in proper attitude. Many variables come into play, including thrust, where you go to idle, temperature, weight, flare technique, winds, etc.

I didin't mean full stall. Anyone who has tried to hold it off too long knows what I mean. In the flare the airplane settles; lose too much speed and it plops.`

Nose wheel landings come from too much speed.

Nice thread . . .