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CTSW compared to CTLS


Al Downs

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It has rudder trim via biased cables and springs, there is n on his ruo movable tabdder.

There are no springs in the rudder trim system like there is for ailerons and elevator. It just increase tension on one side while decreasing tension on the other. It does have a centering spring, but I would not consider that as part of the trim system.

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On my 2006 CTsw, the rudder would gradually deflect with increasing airspeed and even full rudder trim would not correct it.  It was a mystery.   My mechanic added a stiffer centering spring which helped.  He then removed the nose-gear wheel pant and the problem went away completely. 

 

It seemed that the OEM CTsw wheel-pant did not have enough surface area behind the nose wheel steering pivot and would get pushed by the relative wind (and them push the entire rudder control mechanism).  FD recommended we install a CTls wheel pant, which we did.  With more surface area behind the pivot, it does not push the rudder controls mechanism around. 

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Tom, doesn't the centering spring provide the force necessary for the rudder trim mechanism to operate (to hold the rudder against the relative wind)? 

 

Imagine if the centering spring were much weaker, in that case the total ruder trim authority would decrease since, at some intensity of airstream force on the rudder, the spring would compress rather than force the rudder against the relative wind. 

 

Before my CTls wheel pant was installed, even with full rudder trim my rudder pedals would deflect at cruise airspeed, making spring force the limiting factor on rudder trim authority. 

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Tom, doesn't the centering spring provide the force necessary for the rudder trim mechanism to operate (to hold the rudder against the relative wind)? 

 

Imagine if the centering spring were much weaker, in that case the total ruder trim authority would decrease since, at some intensity of airstream force on the rudder, the spring would compress rather than force the rudder against the relative wind. 

 

Before my CTls wheel pant was installed, even with full rudder trim my rudder pedals would deflect at cruise airspeed, making spring force the limiting factor on rudder trim authority.

I suppose the 2 go hand in hand, but the centering spring is just for centering the rudder. It does not effect cable tension. Tension is set by the rods going to the nose gear and the cable turnbuckles. I guess that increasing or decreasing cable tension wouldn't do much good if the centering spring didn't hold the rudder in a neutral position.

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If your cable tension to the rudder is too loose it will cause you to work the peddles a lot more, cause the plane to squirrel around a little from excessive movement and make you hold peddle pressure all the time instead of just adding trim to correct that.

Put a scale on the rudder and pull it left and right about 8.5" to each side and measure the pull. You should be about 23-26 ft/lbs of pressure. I have seen some down around 11-15 ft/lbs and it makes flying much more rudder intensive and makes the plane feel a little squirrely instead of firmly on track. To firm the cable tension up you would need to adjust the turnbuckles upfront just under the lower center panel. It's just loads of fun. (not)

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They are on opposite ends of a bell crank attached to the rudder pedals so they do need to be lengthened. Be careful not to unscrew them to far. There needs to be enough left in the barrel to make certain it is safe. (The manual specifies how much.)

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So I got a story about something strange.... this weekend I took a friend out who really wants to become a pilot. Figured I'd give him the run down and teach him a few things and if he likes it, he can go find a real instructor.

 

Well he has been reading a learning a lot, so he wanted to see a stall. I was in a CTLS.

 

I pulled the power back at 0 flaps, and pitched to maintain a level attitude with the horizon.. nothing out of the norm.. except I never could really stall it. Airspeed never would drop below 50-53 knots. I had the stick full aft, and left it there for some time.. we were of course losing altitude but the speed wouldn't budge.. it never dropped a wing etc. I finally gave up and we moved on. This was more how the ch750 "stalled".. you could ride it down as long as you wanted like that without it dropping a wing or doing anything exciting. But this was a first for me in a CT. Even though stalls in the other CT's I fly are not scary, the plane will get good and slow, and finally let you know when it's time to recover.

 

This plane clearly flies different than the other CTLS, and the SW. But I didn't expect this.. thoughts? I can't really come up with anything that makes sense (we were trimmed for level flight, weight was under max gross, no baggage, no weird wind- it was calm and nice out)

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I have seen this.  In my CT, if I gradually approach the stall, it will just mush, eventually ending up in a wings level sink of about 800-1000fpm with no break.

 

If you want it to break more positively, you can do it at -6 flaps or, instead of keeping wings level, approach the stall more aggressively by progressively feeding in back stick and pull the nose up slowly until the break occurs.

 

The CT has the most docile stall of any plane I have ever flown.

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If I suggested a whip stall or even a stall with more than 30° pitch up entry someone would call it prohibited aerobatics.  I bet somewhere between level and 30 degrees you will start getting a nice break.

 

A more aft CG might work too, without it you seem to lack enough stab authority.

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The CT has the most docile stall of any plane I have ever flown.

 

 

Only thing that surprised me was the ch750... you could "stall" that plane in your sleep, and ride it as long as you want that way without giving the whole situation much thought (other than the fact that you are decreasing altitude quite rapidly)

 

I'll have to play with the SW when they eventually get it fixed again.. but I have stalled the SW many times and it never failed to get real slow and break.

 

 

 

A more aft CG might work too, without it you seem to lack enough stab authority.

 

Seems like this is what is happening. Come to think of it.. in this CTLS, the trim is always pretty far back (aft). Like the whole range you use for normal flying is done from the mid point back. Putting two and two together, I'd venture to say this plane acts/appears to be a little heavy in the nose. I don't remember in the other LS, where the trim ends up (as in...is this an LS thing.. or just this particular aircraft?), but the SW I fly actually operates in the middle of the adjustment. This plane also needs a slightly faster approach speed / lands at a higher indicated speed. I always assumed it was calibrated a little off, or just different from the others... but maybe not?? interesting...

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I have seen this.  In my CT, if I gradually approach the stall, it will just mush, eventually ending up in a wings level sink of about 800-1000fpm with no break.

 

If you want it to break more positively, you can do it at -6 flaps or, instead of keeping wings level, approach the stall more aggressively by progressively feeding in back stick and pull the nose up slowly until the break occurs.

 

The CT has the most docile stall of any plane I have ever flown.

I agree, I can stall my CTLS, but it is very, very difficult, it just does not want to quit flying. Like you say ,this just adds a great margin of safety to all CT's ,especially near the ground, in cases where you have to maneuver abruptly to be able to land. It just does not want to quit flying ! , I love this.

 

Cheers

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May be difference in stall characteristics depending on what your gross weight was.

The CTSW is hard to make it break without getting aggressive about putting it in the stall, but my Champ is the same way. The C150s and C172s I taught in could be made to break rather dramatically.

As has been alluded to, there is a difference in stall technique. I like to practice stalls in what I call a realistic scenario, that is, 15° or 30° flaps, throttle idle, 20-30° bank, pitch down to about 55 kias or so, all of this to emulate a turn from base to final, and then slowly pull back on the stick as if trying to stretch a glide to a landing. That, to me, is the kind of stall that can happen. Practicing "figures" has one doing stalls in a way that is quite unlikely to occur.

Power on (in my opinion more accurately called a departure stall) stalls, slow it way down, use 15° flaps, get to about 4000-4500 RPM and start pulling back slowly on the stick. The idea is to try to emulate a situation where you are taking off over gross at high density altitude with maybe some frost on the wings and all the other bad things you can think of. And the plane just does not want to climb. What a nasty, scary stall because in real life it would be happening really closely to the ground. Doing a power on stall at full throttle with the nose way high in the air may be exciting but to me it is not realistic and doesn't emulate any real life situation, which means it's just a game not a true test of how one recovers.

OK, off my soap box.

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