Whats going on with this stab?

[SixPapaCharlie]

 

[warthog1984]

Leading edge slat on a stabilator. Who'd thunk?

I'm guessing the design had issues with tailplane stalls.

 

[SixPapaCharlie]

That scares me a little

It is a 177 btw

 

[simtech]

I beleive that was done to help with the pilot induced oscillation that the early cardinals had. Operation "cardinal rule"

 

[Pilawt]

I beleive that was done to help with the pilot induced oscillation that the early cardinals had. Operation "cardinal rule"

Former Cessna Manager of Aerodynamics & Flight Test Bill Thompson (in his book Cessna: Wings for The World) wrote that the thin aluminum skins used on the Cardinal to save weight were causing problems:

There was also questionable uniformity of the stabilators, giving as much as 15-mph deviations in minimum trim speeds. On some airplanes they reworked or actually replaced the stabilator with some improvement. This led to the decision to incorporate slots in the stabilators' leading-edges so that they could tolerate a steeper downflow of air without stalling the under-surface of the stabilator. This solved the problem, and a fleetwide "Cardinal Rule" retrofit was planned at no cost to the customer. In the meantime, a service bulletin called for a temporary installation of a simple sheet metal plate that would limit maximum flap deflection to 15º. We were paying the price for these thin skins!

Take a look also at the stabilator of a T-tail Arrow IV. There are slots, fences and fillets, none of which are on the low-tail Arrows. I'm guessing Piper engineers had some interesting handling issues to deal with during flight test.

 

[Henning]

That scares me a little

It is a 177 btw

Why does that scare you? It allows the required deflection when required while minimizing drag in cruise. The slat allows for a thinner airfoil.

 

[warthog1984]

That scares me a little

It is a 177 btw

Ehh... they put it in for control authority issues, not deep stalls.

I'd be more worried if the slots were covered/removed than if the designer put them there.

 

[MAKG1]

177s are actually very nice planes to fly as long as you don't try to open the doors on windy days. Visibility is much better than other high wing Cessnas.

 

[James331]

I beleive that was done to help with the pilot induced oscillation that the early cardinals had. Operation "cardinal rule"

PIO is easy to fix in a aircraft, get a better PIC.

 

[Henning]

PIO is easy to fix in a aircraft, get a better PIC.

Yeah, get in a plane with divergent stick force sometime.

 

[poadeleted20]

I don't think I've ever heard the term "divergent stick force" before, but if you're referring to negative longitudinal static stability, I think I know what you mean. And not many folks survive that experience.

BTW, that's texhnically a slot, not a slat. A slat extends forward from the leading edge, while a slot cuts through the leading edge.

 

[bnt83]

Go fly one. You'll never look at a strutted Cessna the same. (*Handling* as speeds aren't much different than 172 unless its a 177RG)

 

[N801BH]

I don't think I've ever heard the term "divergent stick force" before, but if you're referring to negative longitudinal static stability, I think I know what you mean. And not many folks survive that experience.

BTW, that's texhnically a slot, not a slat. A slat extends forward from the leading edge, while a slot cuts through the leading edge.

Yup... I was just going to point that out......

 

[MAKG1]

Go fly one. You'll never look at a strutted Cessna the same. (*Handling* as speeds aren't much different than 172 unless its a 177RG)

Even the RG has about the same V speeds as a 172. Well, about 5 knots faster. It just has a few more due to the retractible gear (and 125 knots is not a very significant constraint).

The sight picture is a bit different, as that snout sticks way out compared to a 172. Don't get slow on final or you won't be able to see the runway.

 

[Henning]

I don't think I've ever heard the term "divergent stick force" before, but if you're referring to negative longitudinal static stability, I think I know what you mean. And not many folks survive that experience.

BTW, that's texhnically a slot, not a slat. A slat extends forward from the leading edge, while a slot cuts through the leading edge.

I mean the further you get from center the stronger it pushes away, it's freaking scary.

 

[Cpt_Kirk]

Am I the only one who does not like the way the 177 flies?

It feels like a 152 (fixed gear, fixed prop C177). I'd like to think the C177 CS, RG is much better.

 

[nauga]

Ehh... they put it in for control authority issues, not deep stalls.

It was put in to manage stabilator stalls in the flare - definitely a control authority problem if the nose drops suddenly in the flare because your stab stalled

It ain't just for low speed stuff either. F-4 Phantom:

Nauga,
and his q-bellows

 

[poadeleted20]

I mean the further you get from center the stronger it pushes away, it's freaking scary.

I'm afraid I don't understand what you're trying to say. Stick force is supposed to get greater as you depart from neutral. That's the basic definition of positive static stability. OTOH, negative static stability means that stick force decreases as you get farther from the neutral point so when you make a pull on the stick, the aircraft starts pitching and doesn't stop unless you reduce stick force significantly.

 

[N801BH]

I'm afraid I don't understand what you're trying to say. Stick force is supposed to get greater as you depart from neutral. That's the basic definition of positive static stability. OTOH, negative static stability means that stick force decreases as you get farther from the neutral point so when you make a pull on the stick, the aircraft starts pitching and doesn't stop unless you reduce stick force significantly.

Yeah... I "think" the Zenith 601 XL planes shed a few sets of wings because of that issue..

 

[MAKG1]

Am I the only one who does not like the way the 177 flies?

It feels like a 152 (fixed gear, fixed prop C177). I'd like to think the C177 CS, RG is much better.

Not a complaint I've had in a 177RG. It's been a long time since I've been in a 177B, but I don't recall it being all that weak, even taking off from a 6000 foot field (KCOS). 177B is also CS.

 

[nauga]

Yeah... I "think" the Zenith 601 XL planes shed a few sets of wings because of that issue..

There was no single cause determined for the breakups but flutter was a leading suspect in the 601XL issues. Most of the mods were definitely flutter-related, not stability related.

Nauga,
from the root cause cellar

 

[N801BH]

There was no single cause determined for the breakups but flutter was a leading suspect in the 601XL issues. Most of the mods were definitely flutter-related, not stability related.

Nauga,
from the root cause cellar

Correct answer...

 

[bnt83]

Am I the only one who does not like the way the 177 flies?

It feels like a 152 (fixed gear, fixed prop C177). I'd like to think the C177 CS, RG is much better.

Where is that C172 thread where the Piper student got hit first flight in a 172 and felt Pipers were poorer performers afterwards? http://www.pilotsofamerica.com/forum/showthread.php?t=77064

Maybe you flew a dud. Can happen with any make/model.

I've got a 177 with fixed pitch and 150 horse. It carries 72 pounds more fuel than a 172H so yeah its easy to overload.

 

[Pilawt]

I got checked out in a '68 Cardinal the day I got my private license. The airplane was brand new then, so it was all original; didn't even have the stabilator slots yet. I had enough Cherokee time that I was already used to a stabilator, so pitch handling felt normal to me. I had no problem with it.

IMHO the C-177 series has the best roll handling of all high-wing Cessna singles.

 

[docmirror]

The 177 is the only Cessna I like to fly. I think the visibility and controls are quite fine. Of course, I have very little time in all other Cessnas that maybe I'm no authority. Compared to a Bonanza and a Bellanca SV, the 177 is pretty sweet.

 

[Pilawt]

It was put in to manage stabilator stalls in the flare - definitely a control authority problem if the nose drops suddenly in the flare because your stab stalled

It ain't just for low speed stuff either.

Here's why you've never heard of a tailplane stall in a Junkers Ju.52:

 

[Henning]

Am I the only one who does not like the way the 177 flies?

It feels like a 152 (fixed gear, fixed prop C177). I'd like to think the C177 CS, RG is much better.

The only ones I have experience with are all RGs, and I quite like them. They make the best, most versatile, photo platform of any GA plane I have used. I have no qualms with how they fly.

 

[Henning]

I'm afraid I don't understand what you're trying to say. Stick force is supposed to get greater as you depart from neutral. That's the basic definition of positive static stability. OTOH, negative static stability means that stick force decreases as you get farther from the neutral point so when you make a pull on the stick, the aircraft starts pitching and doesn't stop unless you reduce stick force significantly.

It gets greater diverging from center stick, normal planes try to return to neutral when you let go. It was like balancing on top of a ball. It was a design error that got taken care of in the tail redesign.

 

[JimNtexas]

My understanding is that the slot is there to reduce the stick force needed to flare for landing. The 177RG does need a healthy pull in the flare, it's a lot like an Archer in that respect. That nice big trim wheel helps a lot.

Overall the 177RG has far nicer controls than the 172 or 182.

 

[poadeleted20]

It gets greater diverging from center stick, normal planes try to return to neutral when you let go. It was like balancing on top of a ball. It was a design error that got taken care of in the tail redesign.

I think you're confusing static stability with dynamic stability. Static stability is about the change in stick force as you displace the aircraft from its trimmed position. Dynamic stability is about the way it returns (or doesn't return) to the original position after the displacing force is removed from the stick. There is some good information on these aerodynamic fundamentals on John Denker's excellent See How It Flies web site, particularly the section on Equilibrium, Stability, and Damping.

 

[Pilawt]

My understanding is that the slot is there to reduce the stick force needed to flare for landing.

See post #5 above. According to Cessna's Manager of Aerodynamics and Flight Test, they made the "decision to incorporate slots in the stabilators' leading-edges so that they could tolerate a steeper downflow of air without stalling the under-surface of the stabilator."

The stabilator control linkage was also changed with the 1969 Model 177A to adjust stick forces in the flare.

 

[Henning]

I think you're confusing static stability with dynamic stability. Static stability is about the change in stick force as you displace the aircraft from its trimmed position. Dynamic stability is about the way it returns (or doesn't return) to the original position after the displacing force is removed from the stick. There is some good information on these aerodynamic fundamentals on John Denker's excellent See How It Flies web site, particularly the section on Equilibrium, Stability, and Damping.

I'm not confusing anything, I never made the distinction, you made that assumption.

 

[poadeleted20]

I'm not confusing anything, I never made the distinction, you made that assumption.

Try reading the material I linked so next time you use appropriate and accurate terminology to express your meaning. I still don't know whether you're talking static or dynamic stability.

 

[RotorAndWing]

Try reading the material I linked so next time you use appropriate and accurate terminology to express your meaning. I still don't know whether you're talking static or dynamic stability.

Neither does he....

 

[Checkout_my_Six]

yup it's strategery.....

 

[Stewartb]

In a passing view the only time those slots would do much would be in a slow speed/nose down control configuration. I'd think it has to do with stall recovery with an aft CG. Perhaps they needed better control response to validate a more useful aft CG limit.

 

[nauga]

In a passing view the only time those slots would do much would be in a slow speed/nose down control configuration.

They'll be most effective when the stab is leading edge down (for nose-up moment), keeping the flow over the stab attached with nose-up yoke in the flare. Worst case - flow separates, stab stalls, downforce on the tail goes away, nose plunks down hard.

Nauga,
and his downforce

 

[N801BH]

In a passing view the only time those slots would do much would be in a slow speed/nose down control configuration. I'd think it has to do with stall recovery with an aft CG. Perhaps they needed better control response to validate a more useful aft CG limit.

And..... Power would be needed to enhance the airflow into the slots, seeing how they are positioned on the inner part of the horizontal stabilizer where the prop blast would hit.........

 

[nauga]

And..... Power would be needed to enhance the airflow into the slots...

Power might 'enhance' the airflow, but it's not required to make the slot effective.

Nauga,
playing the slots

 

[Checkout_my_Six]

this....that device is to keep the flow attached. VGs are another method that achieves similar results.

They'll be most effective when the stab is leading edge down (for nose-up moment), keeping the flow over the stab attached with nose-up yoke in the flare. Worst case - flow separates, stab stalls, downforce on the tail goes away, nose plunks down hard.

Nauga,
and his downforce