Stall spin in a piper

[martentrapper]

Has anyone noticed the propensity for pipers to stall at low airspeed and in a turn? Seems like there is severasl accidents a year from guys not watching their airspeed in their piper. Just this year we have had an off duty trooper seriously injured in his J-3 north of DLG, and now the PA-12 dowen by Kenai. The trooper was supposed to be a very experienced pilot. T-crafts are similiar I believe.
In contrast, you don't see the champs/citabrias having this problem on a regular basis.
Anyone else have experience in pipers/champs and noticed the difference?

 

[Louis]

Maybe just more Cubs and T-Crafts out there? Just a guess. I lost a friend and co-worker to a stall/spin in a Citabria last fall so they'll do it too....Louis

 

[Mr. Pid]

Has anyone noticed the propensity for pipers to stall at low airspeed and in a turn?

Are you serious? Anyone that has any experience in or around Cubs is aware of "moose stalls." Slow-speed uncoordinated turns can bite you very quickly if you don't have adequate altitude to recover. Of course, most slow-speed uncoordinated turns are done close to the ground while the pilot is preoccupied with something outside the airplane, like a moose. Many pilots have been the victims of such stalls. The fact that Cubs are the predominant low-and-slow airplane makes them the most likely airplane to be involved.

Standard spin entry in any airplane is done by stalling an airplane while uncoordinated.

That isn't to say the accidents you cited were the result of such stalls.

 

[martentrapper]

You bet I'm serious, pid. I think if you look at the flight characteristics of pipers, you'll see that the piper wing will stall at a HIGHER airspeed, for a given bank, than a champ/citabria.
It isn't just inexperienced pilots that this happens to in cubs. The trooper out of dlg was CIRCLING a trapping set. His crash was a classic stall/spin. The recent PA-12 on the Kenai Pen was air dropping supplies to a church group. The wreckage was pictured on statewide news. The fuselage was vertical, 90 degrees to the ground, plus it was a float plane. You don't end up with your cockpit crushed and the fuselage vertical by botching the landing.
While most any stall/spin crash is pilot error, and it is true there are more cubs around, the piper wing does have a higher stall speed in a turn, than a champ.

 

[Mr. Pid]

I guess that's why we see so many Cub owners trading up to Champs?

I don't know a single person that would agree with you. I know a few ex Champ pilots that are now very happy Cub pilots. I'll run your theory past them.

 

[Louis]

I don't speak from a lot of personal experience in Cubs, after about 25-30 hours in the things I decided they aren't for tall guys, but I know plenty of folks who make their living in them and they'll all tell you that the Cub has especially vicious stall charactistics. That does not make it a bad airplane by any means. Like anything else it has to be operated within its limitations. Just about any airplane is perfectly capable of augering in if mishandled. Like one writer said "the Cub is so slow it'll just barely kill you"....Louis

 

[Mr. Pid]

I'd respond that Cubs have exceptionally docile stall characteristics. Low altitude uncoordinated turn stalls would bite you in any airplane I've flown. I will say it's a lot easier to get a Cub uncoordinated than it is a Cessna.

The reason we practice stalls at altitude is for stall awareness and recovery practice. I don't know many guys that practice uncoordinated turning stalls, even at altitude, even when they're focused on stall awareness and recovery, because one of the things we practice is coordination.
My biennial instructor always makes me practice slow flight in steep turns, but not to the stall. Not that it would be a problem, because I guarantee the ball's centered and the airplane has my complete attention.

 

[martentrapper]

Overall performance is probably the main reason a person chooses a certain type of airplane. If you want short field ability over anything else, the cub is pretty much it. The fact that alot of guys doing bush work, or wannabe bush pilot types choose cubs doesn't mean the aircraft is without undesireable traits.
Cub roll control at slow speed is poor. Even at cruise, a cub wing will not respond to aileron movement like a champ wing. At slow speed and in a bank, recovery from a one wing stall in a cub is almost impossible. The stall is also very sudden.
By contrast, the champ is more difficult to stall. Both aileron and rudder control at slow speed is still very good. Sure, you can stall it in a turn, but it will give you warning before it stalls.
I think the reason there are so many stall/spin accidents in cub type aircraft is the lack of warning. The wing drops suddenly. If your low, that's it, your face down in the dirt.

 

[fishnflyak]

supercubs and stalls...

supercubs and stalls...

I believe Mr. Pid to be correct. When you fly low and slow and uncoordinated, bad things happen, in any airplane. There are more cubs in the sky at any one time in Alaska than skeeters sometimes it seems. But not all stall spin accidents are cubs either. Most non-aviation types up here are so friggin ignorant they call all single engined airplanes cubs.

As I recall, at least 2 170's crashed due to stall spin accidents last year alone, killing several family members in each. I saw the one at the Kustatan. Bad stuff.

 

[fishnflyak]

Martentrapper...

Martentrapper...

You say something very interesting in your last post. About the lack of warning in a cub stall. I have seen this as well, but ONLY in a cub with a tricked out wing, big tires, a belly tank, and full wing tanks. Can you see where Im headed with this??

 

[martentrapper]

Can you be more specific about the "tricked out" wing?

 

[fishnflyak]

Martentrapper...

Martentrapper...

anything other than a standard cub wing. VG's, cuffed leading edge, droop tips, gap seals, etc. Anything that's supposed to make the airplane fly slower better and takeoff and land shorter.

 

[fishnflyak]

about stalls..

about stalls..

Ok, so why does a "moose hunters" stall occur in the first place? I will tell you that it's not because the supercub has demonic stall characteristics. And it doesnt stall just because of an uncoordinated turn. The wing of an airplane stalls because the angle of attack is exceeded beyond the point where laminar flow can be maintained across the surface of the airfoil. How do we exceed the angle of attack? We might do it by purposing increasing deck angle until the airplane simply runs out of juice and falls forward to a safe recovery (hopefully), or we might do it by increasing the wing loading. The latter is taught to primary student pilots in the "accelerated stall" manuever. Remember what your instructor always tried to hammer into your head. "an airplane can stall at any speed, in any attitude." True enough but many lack the understanding of why. Wing loading increases as your airplanes weight increases. You notice it when it takes more runway or lake to get airborne. The wing has to work harder. The heavier you are, the higher your angle of attack must be to provide the same amount of lift. Your plane will also fly slower, you will probably burn more gas, and your stall speed increases. There are a few things you can do to counter this, but one must be careful. Moose hunter stalls occur because a pilot may get distracted by something on the ground, be it a moose or a naked woman sunbathing, my personal favorite. Joe cub driver banks hard and pulls some g's trying to stay nice and tight. He get's a little lower for a closer look and pulls a little tighter. He feels like he's "falling" into the turn a little so he kicks in a little more rudder to counter the slip. He throttles back a little more to shallow the turn radius....next thing he knows his stick has no force on it, his left wing tucks under, and before he has time to say..."oh SH**!" he's trapped inside a cage of steel tubing, hopefully alive and not on fire. It happens all the time, and definitely NOT just to cub drivers!

 

[Mr. Pid]

My mechanic has a theory. All Cubs will stall within a fairly predictable range of speed. A stock wing behaves very predictably as it approaches and becomes fully stalled. That approach to stall is what he calls the "gray" area. His notion is that when you add wing tips, stall cuffs, and VGs, the speed of the absolute stall is still relatively close to what it had been in stock configuration, but the "gray" area, that area that you can feel the stall coming, is reduced, or compressed. You have aileron control and pitch authority right up until you don't. No warning. In the hands of a skilled driver that can utilize that slow performance, it's all cool. In the hands of an occasional flyer, not so cool.

His theory, not mine. I find it interesting, though.

 

[fishnflyak]

Mr. Pid,

Mr. Pid,

I think your mechanic has nailed it. All those so called "high lift devices" are there to get one airborne a little quicker while in ground effect, and provide more precise controllability while at extreme low speeds. What they DONT provide is too much warning of imminent/incipient stall. And depending on the "new" wing configuration, all bets are off as to what kind of radical tendencies the airplane with exhibit. Also, what a LOT of pilots may not realize is that when you add bigger heavier tires, a belly tank, add an extra notch of flap, add lotsa gas and basically alter the configuration far beyond what may have ever been intended for this airplane, you might get some very unusual flight characteristics, especiall in a extreme forward CG range. The harder that tail works back there, the higher your stall speed, in ANY configuration!

 

[martentrapper]

They do?

They do?

basically alter the configuration far beyond what may have ever been intended for this airplane,

Come on fishnfly..........nobody does that!
Do they?

 

[Mr. Pid]

Come on fishnfly..........nobody does that!
Do they?

I do! I have lots of mods that increase the utility of my airplane.

Big tires do not effect stall speed or stall characteristics. Neither do belly pods or big wing tanks. Nor do extended baggage compartments, enlarged doors, extended gear, or removable cross tubes. Properly used, these things make an already good airplane better. Lots of guys would say the same for extended wings, stol cuffs, and VGs.

None of these readily available and fully approved mods causes pilot error accidents.

 

[fishnflyak]

Big tires do not effect stall speed or stall characteristics. Neither do belly pods or big wing tanks. Nor do extended baggage compartments, enlarged doors, extended gear, or removable cross tubes. Properly used, these things make an already good airplane better. Lots of guys would say the same for extended wings, stol cuffs, and VGs.

None of these readily available and fully approved mods causes pilot error accidents.

Really? Anytime you add or remove components no matter what they are they change something with the airplanes weight and balance. Items that alter the basic aerodymanics of any airplane, approved or not, will change any existing performance no matter good or bad.

 

[Mr. Pid]

Change performance? Sure. Big tires and belly pods will cost you about 5 mph. Change the stall characteristics? No. Cause pilot error accidents? No.

Every time I load an airplane whether it's with people or freight the weight and balance is a little different and the handling is a little different. It's my responsibility to make the operational adjustments to conduct that flight safely. As long as I follow the aircraft loading limitations the operational adjustments are minor. If I choose to load or operate outside of intelligent limits, bad things might happen. Those same bad things can happen whether the airplane has modifications or not. Stock airplanes crash, too.

 

[fishnflyak]

Change performance? Sure. Big tires and belly pods will cost you about 5 mph. Change the stall characteristics? No. Cause pilot error accidents? No.

Every time I load an airplane whether it's with people or freight the weight and balance is a little different and the handling is a little different. It's my responsibility to make the operational adjustments to conduct that flight safely. As long as I follow the aircraft loading limitations the operational adjustments are minor. If I choose to load or operate outside of intelligent limits, bad things might happen. Those same bad things can happen whether the airplane has modifications or not. Stock airplanes crash, too.

I cannot disagree with anything in your last paragraph. However, anytime your alter an airplane you change it's weight/performance/stall characteristics (good or bad). The only way to know for sure is to learn your airplanes limits. Is this a causle factor in pilot error accidents? If a guy thinks he's smarter than his airplane you better believe it is!