SR22 Instability

[DanAlva83]

Does anyone have any good links to articles or publications that discuss instability particular to the Cirrus SR22? From what I was told the FAA would not certify the aircraft had it not been for the CAPS system.

 

[weilke]

Someone must have confused a couple of things.

Yes, in the US the FAA approved the SR series with a abbreviated stall/spin program under a 'equivalent level of safety' concept. The ELOS determination was based on the presence of the chute and the use of it to recover from a spin. With the chute as the standard spin recovery method, cirrus did not have demonstrate that there are other ways to get out of it.

The european aviation safety authorities did not accept that concept and required Cirrus to demonstrate spin recoveries in a more extensive testing program. Turns out, the plane recovers from spins with the same inputs that would get any other aircraft with the wing in the front an the tail in the back out of a spin.

 

[Cici]

You have to pay for the videos on cirrus approach, but Klapmier had a mid air in the 80s. The kool aid is that they wanted to integrate a frame parachute from the beginning to make the plane safer. Klapmier goes on to say that it is completely false that the plane had to have a chute for certification. They chose to have the chute from beginning.

I do drink the cirrus kool aid. And i firmly believe with the proper training and the pilot getting out of their head that they can fly plane no matter what, the chute makes the plane safer.

 

[ahypnoz]

My impressions are that the Cirrus are more spin resistant but once you get into a spin it is very difficult to get out of one.
(The opposite is also true, the planes that are easier to spin are easier to get out of the spin)

It is not good to spin an airplane at low altitudes (1000 feet or less is usually fatal).

From the below article

To link the rate of “fatal mishaps per year”, the NTSB database was used to find out, how many fatal accidents are stall/spin-related. For the period from 1999 – July 2008 the following numbers were determined for some types of aircraft.
Cessna C172 19%
Piper PA28 8%
Mooney M-20 16%
Cirrus SR20/22 26%
Percentage of stall/spin-related fatal accidents for some aircraft types it is evident that the amount of stall/spin related fatal accidents of the SR20/22 is considerably higher-than-average.

Assuming that the typical mission profiles of a Cessna 172 and an SR20/22 are equivalent (same flight time in low speed phases), and the SR20/22 complies with the requirements according FAR23.221(2), it must be ascertained a contradiction that the SR20/22, as the aircraft with a lower “tendency to spin”, has more than double the rate of “stall/spin-related fatal mishaps per year” than the Cessna 172 (see 6.2.4), as the aircraft which complies only with the spinning code but not with the FAA spin resistance option.

The article below also recommends the following depending on certification

A placard “AVOID STALL! DO NOT SPIN! Spin recovery has not been
demonstrated.” must be placed in a highly visible position at the instrument
panel.
Remarks: Most pilots are probably not aware that their aircraft is designed under a
principally different regulation as regards the stall and spin behaviour (e.g. the
difference between C350 and C400). As a result, they risk entering a flight state that
is not recoverable. Clearer information must be given to the pilot to prevent
intentional and unintentional spinning.

As most of the pilots are not aware of the conceptual difference between spin
recoverable aircraft and spin resistant aircraft, the wording of the placard must differ
from the standard placard. “Spins prohibited” is not appropriate for spin resistant
aircraft.

(a very interesting article on spins, more than you will ever want to read in one sitting)
https://www.easa.europa.eu/sites/default/files/dfu/EASA_REP_RESEA_2008_3.pdf

 

[SixPapaCharlie]

That's Internet myth.

Cirrus recovered from 61 test spins using standard recovery technique in Europe with no anomalies noted by the test pilots.
The pilots remarked that it seemed difficult to get the aircraft to enter a spin.

 

[benyflyguy]

 

[midlifeflyer]

My impressions are that the Cirrus are more spin resistant but once you get into a spin it is very difficult to get out of one.
(The opposite is also true, the planes that are easier to spin are easier to get out of the spin)

First time I've heard this one.

 

[alfadog]

First time I've heard this one.

Sure, like a Cessna 172 which is hard to spin but, oh, wait...

 

[weilke]

The pilots remarked that it seemed difficult to get the aircraft to enter a spin.

I would hope so as this was a design goal.

 

[Dean V]

Does anyone have any good links to articles or publications that discuss instability particular to the Cirrus SR22? From what I was told the FAA would not certify the aircraft had it not been for the CAPS system.

A SR22 does not have an instability issue and it has descent stall characteristics. Normally when aircraft are certified they must demonstrate the can be recovered from a one turn spin. The SR22 did not meet that minimal requirement for certification and the chute was accepted as the recovery method.

The SR22 has poor recovery characteristics from spins and the manufacturer states in the POH that CAPS is the only recovery method. There are some who point to some independent flight tests where the aircraft demonstrated spin recovery. There is also a documented situation when a pilot demonstrating a spin could not recover and pulled the chute. What a acrobatic pilot can do and what the average Private pilot can demonstrate are not comparable.

An average pilot who believes he could recover an SR22 at any CG and weight from a spin without chute deployment is rather foolish.

 

[Rein Hart]

I would hope so as this was a design goal.

Indeed. At the bottom of linked page, the wing’s leading edge design for spin prevention is explained.

http://whycirrus.com/engineering/stall-spin.aspx

 

[FastEddieB]

First time I've heard this one.

I think it depends.

I am in general agreement that certain design decisions which delay the stall over the outboard span of the wing can lead to more problematical dynamics once the stall does occur.

This is an older video of a Cirrus accident, but well worth a watch. It mentions how Cirrus designed the wing to avoid spins, but what can happen if pushed beyond a point.

I was a Cirrus instructor, and have probably done a hundred or more stalls in them, mostly with students. I never saw any untoward stall behavior. But there were enough pilot anecdotes of sudden spin or near-spin entries, and fatal accidents similar to the one linked above, that I was always “on my toes” when stalling a Cirrus. I liked to be at 5,000’ agl and always had the CAPS handle in mind if things got too weird.

 

[midlifeflyer]

I think it depends.

I am in general agreement that certain design decisions which delay the stall over the outboard span of the wing can lead to more problematical dynamics once the stall does occur.

No doubt. I was only questioning the general proposition that difficulty entering a spin automatically means difficulty exiting it (and vice versatility).

Yes, I've done stalls in Cirrus too, including falling leaf stalls. I didn't see any untoward behavior either.

 

[Juliet Hotel]

What a acrobatic pilot can do and what the average Private pilot can demonstrate are not comparable.

An average pilot who believes he could recover an SR22 at any CG and weight from a spin without chute deployment is rather foolish.

Except for the inclusion of the chute as an option, you could say the same thing for just about any airplane.

 

[tspear]

A SR22 does not have an instability issue and it has descent stall characteristics. Normally when aircraft are certified they must demonstrate the can be recovered from a one turn spin. The SR22 did not meet that minimal requirement for certification and the chute was accepted as the recovery method.

The SR22 has poor recovery characteristics from spins and the manufacturer states in the POH that CAPS is the only recovery method. There are some who point to some independent flight tests where the aircraft demonstrated spin recovery. There is also a documented situation when a pilot demonstrating a spin could not recover and pulled the chute. What a acrobatic pilot can do and what the average Private pilot can demonstrate are not comparable.

An average pilot who believes he could recover an SR22 at any CG and weight from a spin without chute deployment is rather foolish.

Jeez, believe OWT's much? This has pretty much all been debunked multiple times on POA; even in this thread.

Tim

 

[tspear]

No doubt. I was only questioning the general proposition that difficulty entering a spin automatically means difficulty exiting it (and vice versatility).

Yes, I've done stalls in Cirrus too, including falling leaf stalls. I didn't see any untoward behavior either.

Actually multiple aeronautical engineers have tried to explain it to me. I have yet to understand it.... But basically many of the techniques, some of which Cirrus uses, which increase control authority through the stall (e.g. inboard wing incidence is higher than outboard with the ailerons) or prevent the stall from occurring can actually make it harder or take longer to recover.

Tim

 

[Clip4]

Except for the inclusion of the chute as an option, you could say the same thing for just about any airplane.

Except people aren’t disputing a manufacture’s procedure for spin recovery claiming it is BS in just about any other airplane.

 

[weilke]

Indeed. At the bottom of linked page, the wing’s leading edge design for spin prevention is explained.

http://whycirrus.com/engineering/stall-spin.aspx

It's not like this was a revolutionary new concept. But yes, the idea was to make it hard to spin the thing and to recover with the chute. But the reality is, if you work at it, you can get them into a spin, and just like any other high performance aircraft, you are in for a wild ride if it happens.

 

[weilke]

I wish Cirrus had built an experimental version with a inverted oil/fuel system and sent it on the air-show circuit. Cruise up to altitude, spin it down 2-3 rounds, recover and go right into a nice barrel roll or loop with the energy.

 

[Cici]

I wish Cirrus had built an experimental version with a inverted oil/fuel system and sent it on the air-show circuit. Cruise up to altitude, spin it down 2-3 rounds, recover and go right into a nice barrel roll or loop with the energy.

They used to sell kits. I see a few experimental Cirri around from time to time. Mygoflight houses one at KAPA.

 

[Dean V]

I wish Cirrus had built an experimental version with a inverted oil/fuel system and sent it on the air-show circuit. Cruise up to altitude, spin it down 2-3 rounds, recover and go right into a nice barrel roll or loop with the energy.

Don’t let that stop you. You can modify one yourself.

 

[FastEddieB]

Don’t let that stop you. You can modify one yourself.

How?

 

[Dean V]

Jeez, believe OWT's much? This has pretty much all been debunked multiple times on POA; even in this thread.

Tim

https://www.avweb.com/news/watch-this-spin-results-in-chute-pull/

 

[Dean V]

How?

Make the mods and turn it into an experimental.

 

[Kenny Phillips]

https://www.avweb.com/news/watch-this-spin-results-in-chute-pull/

Yeah, but: "The salesman said he’d done the same sort of demo at least 30 and as many as 50 times in the previous six months and thus may have been over-confident in a successful recovery."

 

[Dean V]

Question: Has any spin testing been conducted in the CIRRUS airplanes?

CIRRUS Engineer: Yes, CIRRUS has done spin testing in both the SR20 and the SR22, and we’ve done a variety of spins in both models. But, that’s different than saying we’ve completed the entire spin matrix in each plane in every conceivable condition and configuration – because we haven’t. Eventually we decided to take the logical stand that spin prevention is the key to preventing needless fatalities, and attempts to make the airplane spin-certified would just muddy the waters.
Spin recovery requirements are very stringent. The upside of the cuffs – that they give greater control in the slow flight regime – also have, like every aircraft feature, a compromise, and that is that they can cause an aircraft to take more than the required one-turn recovery rotation to be eligible to be spin-certified. But people should understand that even though an airplane may be spin certified, certain ‘cliffs,’ as we call them, can still exist in spin aerodynamics making recovery uncertain.

 

[Capt. Geoffrey Thorpe]

With a little effort, purd near any aircraft can be spun right into the ground. Look in the NTSB data base for fatal spins in Pitts - which are pretty much designed to spin, spin, spin till daddy takes the T-bird away. (But can be unforgiving if you eff up and try to put the stick forward before the rudder stops the rotation).

 

[weilke]

They used to sell kits. I see a few experimental Cirri around from time to time. Mygoflight houses one at KAPA.

What 'kit' are you talking about ?

 

[FastEddieB]

Make the mods and turn it into an experimental.

What class of Experimental do you suggest?

 

[Kenny Phillips]

What 'kit' are you talking about ?

The old VK-30, of course. I think that a huge percentage of them crashed, including one flown by Bob Overmyer.

 

[Tantalum]

From what I was told the FAA would not certify the aircraft had it not been for the CAPS system.

No. No. No. No.

 

[tspear]

https://www.avweb.com/news/watch-this-spin-results-in-chute-pull/

Not one aspect of that article backs up your spurious OWT.

Tim

 

[Tantalum]

My impressions are that the Cirrus are more spin resistant but once you get into a spin it is very difficult to get out of one.

What is this based on? Have you spun a Cirrus, and several other frames to compare? During European certification the aircraft recovered just fine without any kind of abnormal behavior

**they recommend using the chute because, even though we're all "the best pilots we know" most day to day pilots will not be able to recover from a spin.. frankly, the fact that you even entered one would suggest that you were already well behind the aircraft.. so why risk pulling the wings off or dying? Just pull the chute

instability particular to the Cirrus SR22

Go fly one.. the plane is the most stable platform I've flown.. it basically just goes exactly where you point it. If you know how to use the rudder pedals you can hold the plane in a falling leaf stall no problem. The stall is very benign.. my friend didn't even realize we were stalled outside of the audible warning and the airspeed being crazy low. By the way, it will require more disciple to fly than a 172, a Cirrus won't let you drag it in at 55 knots and get away with the kind of sloppy airmanship a Skyhawk will.. but neither will a Mooney, Bonanza, or any real airplane.

People make up this stuff about the Cirrus because they're either grossly misinformed or because they think it's cool for some reason

 

[midlifeflyer]

Actually multiple aeronautical engineers have tried to explain it to me. I have yet to understand it.... But basically many of the techniques, some of which Cirrus uses, which increase control authority through the stall (e.g. inboard wing incidence is higher than outboard with the ailerons) or prevent the stall from occurring can actually make it harder or take longer to recover.

Tim

They all use techniques like that. This is the blurb on "inboard wing incidence is higher than outboard with the ailerons," to quote you, from Chapter 4 of the Pilot's Handbook of Aeronautical Knowledge, a standard aviation text for decades.

In most straight-wing aircraft, the wing is designed to stall the wing root first. The wing root reaches its critical AOA first making the stall progress outward toward the wingtip. By having the wing root stall first, aileron effectiveness is maintained at the wingtips, maintaining controllability of the aircraft. Various design methods are used to achieve the stalling of the wing root first. In one design, the wing is “twisted” to a higher AOA at the wing root. Installing stall strips on the first 20-25 percent of the wing’s leading edge is another method to introduce a stall prematurely.​

The lowly Cessna 172 (difficult to spin; easy to recover) wing is an example of the twist.

 

[tspear]

@midlifeflyer
Yup, like I said that was just one example given; and it always is a compromise. Assuming, and this is a big assumption, I followed it correctly, the greater the delta between the inner wing chord and the outer wing chord affects the ability of the plane to recover from a spin. In Cirrus, the wing chord delta is very noticeable, much more than I see on a Cessna.
But in either case, we need someone who actualy understands this stuff to try and explain it. Not me

Tim

 

[Stingray Don]

The lowly Super Awesome Cessna 172

FTFY!

 

[weilke]

The old VK-30, of course. I think that a huge percentage of them crashed, including one flown by Bob Overmyer.

Mh, yeah, for one they haven't sold that kit in decades and it has like nothing in common with the SR series.

My suggestion would have been for the factory to build an SR22 in the R&D category and have a demo pilot do 'gentlemans acro' in it. Would go a long way to convince the doubters that the wings won't fall off or the spin is unrecoverable.

 

[Tantalum]

My suggestion would have been for the factory to build an SR22 in the R&D category and have a demo pilot do 'gentlemans acro' in it. Would go a long way to convince the doubters that the wings won't fall off or the spin is unrecoverable.

Text Johnson tried a stunt in the 707, was that pre or post certification?

What kind of legal ramifications would there be for someone from Cirrus doing a gentleman's acro? As much as I'd love to see that I bet there would be some kind of precedent against leading by example

Mind you, there are YouTube videos of pilots rolling Cirrus aircraft.. and of more than 7,000 built I'm sure people have done some stupid things in them yet not a single in-flight breakup

 

[Capt. Geoffrey Thorpe]

What kind of legal ramifications would there be for someone from Cirrus doing a gentleman's acro? As much as I'd love to see that I bet there would be some kind of precedent against leading by example

The first ones that pop into my head...
Bob Hoover in a Shrike.
Mat Younkin in a Twin Beech

 

[weilke]

What kind of legal ramifications would there be for someone from Cirrus doing a gentleman's acro? As much as I'd love to see that I bet there would be some kind of precedent against leading by example

Dunno, a sign that says 'Bob here is what we call an 'expert', don't do this at home kids'.

This would be a single use plane. They wouldn't be able to put in the logbook 'no limitations were exceeded' when they return it to a standard AW certificate. Purely a marketing tool.

But then, they dont market to pilots, they just happen to mostly sell to pilots. If you already have 95% of your market segment, there is not much motivation to push further.

Mind you, there are YouTube videos of pilots rolling Cirrus aircraft.. and of more than 7,000 built I'm sure people have done some stupid things in them yet not a single in-flight breakup

I dont consider people doing stupid **** and getting away with it a good marketing tool. If you can fly loops in a Beech 18 or a piston Commander, you can safely do so in a Cirrus.