X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 06 Jan 2013 08:34:09 -0500 Message-ID: X-Original-Return-Path: Received: from nm33-vm0.bullet.mail.bf1.yahoo.com ([72.30.239.200] verified) by logan.com (CommuniGate Pro SMTP 6.0.1) with ESMTPS id 5997172 for lml@lancaironline.net; Sat, 05 Jan 2013 17:26:08 -0500 Received-SPF: none receiver=logan.com; client-ip=72.30.239.200; envelope-from=bu131@swbell.net Received: from [98.139.212.151] by nm33.bullet.mail.bf1.yahoo.com with NNFMP; 05 Jan 2013 22:25:34 -0000 Received: from [76.13.13.223] by tm8.bullet.mail.bf1.yahoo.com with NNFMP; 05 Jan 2013 22:25:34 -0000 Received: from [127.0.0.1] by smtp102-mob.biz.mail.ac4.yahoo.com with NNFMP; 05 Jan 2013 22:25:34 -0000 X-Yahoo-Newman-Id: 45625.39195.bm@smtp102-mob.biz.mail.ac4.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: t23QBa8VM1kmmku0MRPbam_CLMX.oTZDq536UDK2A_A.dqy yQ6BDyhw3JqWCy6jfD.zQjjRGKvf49c6NbQqy3aJA7gr3IsZXueKfsVMib9q m8JbtE5IyC9dcb6RIO1e.FvfgtEbwyTsCL6RXlRyE_X3Gh_EBD7rs.UmkoPS qdEb8T_xFkVdJSSCj86RhlYJTKpAaEdGpRtdsKuZ5gP5KWtTGS5T4Z.2l3ce hfC.rT3puINDyYQWAPPDesS3Xvjp.8chxHivJaoVbB2bleR28s0iq9ylaJbz Fjmubv8CufvJzQFk_lgcztTz.k7Kup.Iu0eQR960lYusXdlhPv7C7kgNdB2s R2sjUcymXuUOEDlaVkQyMtYhu.FITBOhhjLPlh1WnTx72N8kJ9xRpaw0wzud n5VDfrf8F17WY5B.EpWkcKTs5WXmZqC928aJiTR726in4tmJJPY9CceU._Cx SiJRvNQBw_VoPe0eKQQlO1.aZA8b0bJWv7Izineyq.OXs2A0NsNR0lzOv9BV o2Eq0nmv.BfoJD4O_aZT0eeMu_hMWcHqKdv_Pk3RbAQOHK8YEQIggVSvBLpT lAnb9bVlrSZIEbdQTRPlYjY7Q_G2LWWAmOEXIKkbc5yBqikebPSCRN5cViA2 zCBa0uVYNnOJIlA1gj88fjanOjw9MSHmlt27ChR5z6dUifBizJ2Y3CdyowiF 0eRg- X-Yahoo-SMTP: eERJTJCswBCu0l0QxPF_oyc3n8.DQSe28zFd2dc- Received: from [192.168.1.103] (bu131@99.181.53.104 with xymcookie) by smtp102-mob.biz.mail.ac4.yahoo.com with SMTP; 05 Jan 2013 14:25:33 -0800 PST Subject: Re: [LML] Re: stalls References: From: Andres Katz Content-Type: multipart/alternative; boundary=Apple-Mail-FD5F0A81-FBA1-46E0-AB8B-1330B410F3A6 In-Reply-To: X-Original-Message-Id: <0207A4CF-D2FF-4A3D-A1CA-C4D007BB314F@swbell.net> X-Original-Date: Sat, 5 Jan 2013 12:09:13 -0600 X-Original-To: Lancair Mailing List Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (1.0) X-Mailer: iPad Mail (9B206) --Apple-Mail-FD5F0A81-FBA1-46E0-AB8B-1330B410F3A6 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 You hit the nail in the head, I hope everyone reads your post=20 No one reasonable that flies anything non Acro will get into full developed s= talls We practice "entry Ito stall" to avoid a full developed stall.=20 Clarifying this point would have prevented bill from getting upset. It's been an interesting thread nevertheless Ak 500 hrs ivp 250 hrs evo Sent from my iPad On Jan 5, 2013, at 10:19 AM, "Jarrett Johnson" wrote= : > Matt your saying you don't think the likes of a DC-9 or an MD-80, any mode= l of Lear [or any jet w/ rear engines above the wings or T-Tails] hasn't bee= n stalled to validate that turbulent airflow doesn't impact the engine perfo= rmance or blanket the horizontal tail prior to being certified by the FAA fo= r production?? I would agree that the simulator manufactures don't model fl= ight in their simulators past the point of stall as there are too many varia= bles to do so accurately giving repeatable and consistent results, but that d= oesn't mean that certified airframes [Jet or any other type] aren't tested f= or stall and behavior while stalled. > =20 > Sites like http://en.wikipedia.org/wiki/1963_BAC_One-Eleven_test_crash wou= ld lead me to believe they do in fact flight test aircraft to these levels d= uring flight testing of new commercial aircraft. I've found other sites that= talk about the deep stall problems with and early Gloster jet as well as Ca= nadair, 727 and DC-9. The 727 incident caused Boeing [according to this site= ] to swear never to build another T-tail aircraft. I believe 'Stick Pushers'= were brought about due to testing of Dc-9's and their resultant like for de= ep stalls. > =20 > Something that seems to keep getting missed in this whole discussion is th= e terminology of "Stall". Maybe this is where the confusion comes from vario= us people who [possibly] see things similarly but are describing them differ= ently. There are different levels of a stall. An "Approach to Stall" is a mu= ch different thing that an full on "Aerodynamic Stall", a "Deep Stall" or an= "Accelerated Stall". > =20 > The definition of a Stall [or Aerodynamic Stall] is " a reduction in the l= ift coefficient generated by a foil as angle of attack increases. This occur= s when the critical angle of attack of the foil is exceeded. The critical an= gle of attack is typically about 15 degrees, but it may vary significantly d= epending on the fluid, foil, and Reynolds number." [according to Wiki. ] > =20 > Another definition [Wiki again] is "stalls in fixed-wing flight are often e= xperienced as a sudden reduction in lift as the pilot increases angle of att= ack and exceeds the critical angle of attack" > =20 > A Deep stall is generally defined as pushing the aircraft past the point o= f stall and/or holding it in a stalled condition such that the horizontal ta= il also becomes 'stalled'. It can be construed as causing the stalled/turbul= ent wake from the wing to blank the horizontal stabilizer. Another descripti= on is to dynamically stall the aircraft via maneuvering [think a "tail slide= " type maneuver]. It is generally described as reached/developed when the el= evator is no longer effective, either by blanking of the horizontal tail or l= oss of airflow over the tail. Typically deep stalls are pitch stable with a e= xtremely high rate of decent and are [in the case of blanked H-tails] un-rec= overable. > =20 > Rather than re-write it, I've cut and pasted an excerpt from the FAA pilot= s "Airplane Handbook" [Found here] http://www.faa.gov/library/manuals/aircr= aft/airplane_handbook/media/faa-h-8083-3a-3of7.pdf on the topic of approach t= o stall. > =20 > _____________________________________________________________________ > =20 > APPROACHES TO STALLS (IMMINENT STALLS)=E2=80=94POWER-ON OR POWER-OFF > An imminent stall is one in which the airplane is approaching a stall but i= s not allowed to completely stall. This stall maneuver is primarily for prac= tice in retaining (or regaining) full control of the airplane immediately up= on recognizing that it is almost in a stall or that a stall is likely to occ= ur if timely preventive action is not taken. The practice of these stalls is= of particular value in developing the pilot=E2=80=99s sense of feel for exe= cuting maneuvers in which maximum airplane performance is required. These ma= neuvers require flight with the airplane approaching a stall, and recovery i= nitiated before a stall occurs. As in all maneuvers that involve > significant changes in altitude or direction, the pilot must ensure that t= he area is clear of other air traffic before executing the maneuver. > =EF=BB=BF > These stalls may be entered and performed in the attitudes and with the sa= me configuration of the basic full stalls or other maneuvers described in th= is chapter. However, instead of allowing a complete stall, when > the first buffeting or decay of control effectiveness is noted, the angle o= f attack must be reduced immediately by releasing the back-elevator pressure= and applying whatever additional power is necessary. Since the > airplane will not be completely stalled, the pitch attitude needs to be de= creased only to a point where minimum controllable airspeed is attained or u= ntil adequate control effectiveness is regained. The pilot must promptly rec= ognize the indication of a stall and take timely, positive control action to= prevent a full stall. Performance is unsatisfactory if a full stall occurs,= if an excessively low pitch attitude is attained, or if the pilot fails to t= ake timely action to avoid excessive airspeed, excessive loss of altitude, o= r a spin. > =EF=BB=BF > =EF=BB=BF_______________________________________________________________ > =20 > Therefore when I say that I've had to demonstrate approach to stall and re= covery in the turbo-prop twin that I fly, I mean.. reduce speed to the first= sign of stall [horn and buffet in my case] and then recover. However, in do= ing this maneuver everything is dynamic, at flight idle with full flaps I'm l= osing several knots per second so, while I may get confirmation of the appro= ach to stall and initiate recover [hold the pitch angle and increase power] t= he time required to react and the engines to respond, allows the aircraft to= get past the 'initial' state of the stall and reach some form of a stalled c= ondition [as noted by the several hundred fpm decent that occurs while I'm p= itched at +10deg deck angle]. I'm pretty sure this is typical of anyone doin= g training of this sort per discussion with my check pilot. In this airframe= [C425] it's a non-event as it behaves very well in this phase of flight. > =20 > The same applies to simulators, I was just in one [a full motion simulator= ] like 1.5yrs ago and we did approach to stalls in it as well, that isn't to= say that we 'stalled the aircraft' or that I'm saying a simulator will 'sim= ulate' the aerodynamics of a full stall or a deep stall, simply that the sim= ulator can 'simulate accurately' the effects of an approach to stall such th= at the pilot can effectively recognise and take appropriate action to avoid/= (recover from) the stall [in the bigger 'stuff' this is identified at 'stick= shaker']. In my comment [as you've clipped below] I didn't differentiate th= e 'approach to stall' as it pertains to simulators clearly, I guess I need t= o proof-read my writing better LOL. > =20 > Being able to fly in these scenarios has another advantage, for those who f= lying w/ TWAS systems. In our aircraft/company the procedure when a TWAS ale= rt is issued, the procedure is to "pitch to stick shaker", increase to max t= orque, verify speed reduction to Vx and hold this pitch angle/airspeedfor cl= imb or until the emergency is resolved". If you don't know at what speed th= at is [due to not flight testing your airframe to those speeds], how are you= going to "fly" to it? How would you even practice this maneuver w/out know= ing your speeds or having the proper alerting systems [a properly calibrated= stall warning [AOA] system, bitching Betty etc]. > =20 > Fwiw > =20 > Jarrett Johnson > 235/320 55% [and holding] > =20 > =20 > =20 > On Fri, 04 Jan 2013 15:38:44 -0500, Matt Hapgood wrote: > Off-topic technical comment. I'm no expert, but I have taken an airplane (= a twin turbo-prop) through the data collection process for stall buffets and= taken a simulator through FAA approval (high level, full motion). The airc= raft was definitely not stalled, nor does the simulator simulate a stall. =20= >=20 > Years ago I asked the sim experts (aero engineers) why they didn't model t= he stall phase. Their short and simple explanation when something like this= : If you make a reasonably good paper airplane and throw it in the air, you= can reasonably model it's flight. Now try throwing an unfolded sheet of pa= per in the air. Got any idea where it's gonna go or what it's gonna do? Th= at's what it would be like trying to model a stall. >=20 > Matt >=20 > From: Jarrett Johnson > Reply-To: Lancair List > Date: Friday, January 4, 2013 2:01 PM > To: Lancair List > Subject: [LML] Re: stalls >=20 > --- 4-The thought that Jets aren't tested in slow flight [and slower] is f= alse as well, all of these jets are fully tested before being signed off an '= released' for production. All pilots in training then fly these maneuvers wh= ile doing type training [in simulators which duplicate the tested results]. I= f you think that once you get your Airline Transport License your done w/ st= all/approach to stall training for the rest of your flying career, your mist= aken. > =20 >=20 > =20 >=20 --Apple-Mail-FD5F0A81-FBA1-46E0-AB8B-1330B410F3A6 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
You hit the nail in the he= ad, I hope everyone reads your post 
No one reasonable that f= lies anything non Acro will get into full developed stalls
We prac= tice "entry Ito stall" to avoid a full developed stall. 
Clar= ifying this point would have prevented bill from getting upset.
It= 's been an interesting thread nevertheless
Ak 500 hrs ivp 250 hrs e= vo

Sent from my iPad

On Jan 5, 2013, at 10:19 AM, "Jarr= ett Johnson" <hjjohnson@sasktel.= net> wrote:

p{margin: 0;padding: 0;}

Matt your saying you don't think the= likes of a DC-9 or an MD-80, any model of Lear [or any jet w/ rear engines a= bove the wings or T-Tails] hasn't been stalled to validate that turbulent airflow= doesn't impact the engine performance or blanket the horizontal tail prior t= o being certified by the FAA for production??  I would agree that the simulator manufactures don't model flight in their simulators past the point= of stall as there are too many variables to do so accurately giving repeatable a= nd consistent results, but that doesn't mean that certified airframes [Jet or a= ny other type] aren't tested for stall and behavior while stalled.

 

Sites like http://en.wikipedia.org/wiki/1963_BAC_One-Eleven_test_crash&nb= sp;would lead me to believe they do in fact flight test aircraft to these levels duri= ng flight testing of new commercial aircraft. I've found other sites that talk about the deep stall problems with and early Gloster jet as well as Canadair= , 727 and DC-9. The 727 incident caused Boeing [according to this site] to swe= ar never to build another T-tail aircraft. I believe 'Stick Pushers' were broug= ht about due to testing of Dc-9's and their resultant like for deep stalls.

=

 

Something that seems to keep getting missed in this whole discussion is t= he terminology of "Stall". Maybe this is where the confusion comes from various people who [possibly] see things similarly but are describing them differently. There are different levels of a stall. An "Appr= oach to Stall" is a much different thing that an full on "Aerodynamic Stall", a "= Deep Stall" or an "Accelerated Stall".

 

The definition of a Stall [or Aerodynamic Stall] is " a reduction in= the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded. The critical angle of attack is= typically about 15 degrees, but it may vary significantly depending on the fluid, foil, and Reynolds number." [according to Wiki. ]

 

Another definition [Wiki again] is "stalls in fixed-wing flight are often= experienced as a sudden reduction in lift as the pilot increases angle of at= tack and exceeds the critical angle of attack"

 

A Deep stall is generally defined as pushing the aircraft past the point o= f stall and/or holding it in a stalled condition such that the horizontal tail= also becomes 'stalled'. It can be construed as causing the stalled/turbulent= wake from the wing to blank the horizontal stabilizer. Another descript= ion is to dynamically stall the aircraft via maneuvering [think a "tail slide" t= ype maneuver]. It is generally described as reached/developed when the elevator i= s no longer effective, either by blanking of the horizontal tail or loss o= f airflow over the tail. Typically deep stalls are pitch stable with a extreme= ly high rate of decent and are [in the case of blanked H-tails] un-recoverable.=

 

Rather than re-write it, I've cut and pasted an excerpt from the FAA pilo= ts "Airplane Handbook" [Found here]  http://www= .faa.gov/library/manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-3of7= .pdf on the topic of approach to stall.

 

_____________________________________________________________________

=

 

APPROACHES TO STALLS (IMMIN= ENT STALLS)=E2=80=94POWER-ON OR POWER-OFF

An imminent stall is one in which the airplan= e is approaching a stall but is not allowed to completely stall. This stall maneuv= er is primarily for practice in retaining (or regaining) full control of the airplane immediately upon recognizing that it is almost in a stall or that a stall is likely to occur if timely preventive action is not taken. The practice of these stalls is of particular value in developing the= pilot=E2=80=99s sense of feel for executing maneuvers in which maximum airpl= ane performance is required. These maneuvers require flight with the airplane approaching a stall, and recovery initiated before a stall occurs. As in all= maneuvers that involve

significant changes in altitude or direction, the pilot mu= st ensure that the area is clear of other air traffic before executing the maneuver.

=EF=BB=BF

These stalls may be entered and performed in the attitudes= and with the same configuration of the basic full stalls or other maneuvers described in this chapter. However, instead of allowing a complete stall, when

the first buffeting or decay of control effectiveness is n= oted, the angle of attack must be reduced immediately by releasing the back-elevat= or pressure and applying whatever additional power is necessary. Since the

airplane will not be completely stalled, the pitch attitud= e needs to be decreased only to a point where minimum controllable airspeed is attai= ned or until adequate control effectiveness is regained. The pilot must promptly= recognize the indication of a stall and take timely, positive control action= to prevent a full stall. Performance is unsatisfactory if a full stall occurs, i= f an excessively low pitch attitude is attained, or if the pilot fails to take= timely action to avoid excessive airspeed, excessive loss of altitude, or a spin.

=EF=BB=BF

=EF=BB=BF_____________________= __________________________________________

 

Therefore when I say that I've had to demonstrate approach to stall and recovery in the turbo-prop twin that I fly, I mean.. reduce speed to the fir= st sign of stall [horn and buffet in my case] and then recover. However, in doi= ng this maneuver everything is dynamic, at flight idle with full flaps I'm= losing several knots per second so, while I may get confirmation of the= approach to stall and initiate recover [hold the pitch angle and increase po= wer] the time required to react and the engines to respond, allows the aircraft t= o get past the 'initial' state of the stall and reach some form of a stalled condition [as noted by the several hundred fpm decent that occurs while I'm pitched at +10deg deck angle]. I'm pretty sure this is typical of anyone doi= ng training of this sort per discussion with my check pilot. In this airframe [C425] it's a non-event as it behaves very well in this phase o= f flight.

 

The same applies to simulators, I was just in one [a full motion simulator] like 1.5yrs ago and we did approach to stalls in it as well,= that isn't to say that we 'stalled the aircraft' or that I'm saying a simula= tor will 'simulate' the aerodynamics of a full stall or a deep stall, simply tha= t the simulator can 'simulate accurately' the effects of an approach to stall s= uch that the pilot can effectively recognise and take appropriate action to avoid/(recover from) the stall [in the bigger 'stuff' this is identifie= d at 'stick shaker']. In my comment [as you've clipped below] I didn't differenti= ate the 'approach to stall' as it pertains to simulators clearly, I guess I need= to proof-read my writing better LOL.

 

Being able to fly in these scenarios has another advantage, for those who= flying w/ TWAS systems. In our aircraft/company the procedure when a TWAS al= ert is issued, the procedure is to "pitch to stick shaker", increase to max= torque, verify speed reduction to Vx and hold this pitch angle/airspeed= for climb or until the emergency is resolved".  If you don't know at what s= peed that is [due to not flight testing your airframe to those speeds], how are y= ou going to "fly" to it?  How would you even practice this maneuver w/out knowing your speeds or having the proper alerting systems [a properly calibr= ated stall warning [AOA] system, bitching Betty etc].

 

Fwiw

 

Jarrett Johnson

235/320  55% [and holding]

 

 

 

On Fri, 04 Jan 2013 15:38:44 -0500, Matt Hapgood <matt.hapgood@alumni.duke= .edu> wrote:

Off-topic technical comment.  I'm no expert, but I have ta= ken an airplane (a twin turbo-prop) through the data collection process for stal= l buffets and taken a simulator through FAA approval (high level, full motion)= .=20  The aircraft was definitely not stalled, nor does the simulator simula= te a stall.  

Years ago I asked the sim experts (aero engineers) why they did= n't model the stall phase.  Their short and simple explanation when somethi= ng like this:  If you make a reasonably good paper airplane and throw it i= n the air, you can reasonably model it's flight.  Now try throwing an unfolded sheet of paper in the air.  Got any idea where it's gonna go o= r what it's gonna do?  That's what it would be like trying to model a stall.

Matt

From:= Jarrett Johnson <hjjohnson= @sasktel.net>
Reply-To: Lancair List <lml@lancairo= nline.net>
Date: Friday, January 4, 2013 2:01 PM
To: Lancair List <lml@lancaironline.net>
Subject: [LML] Re: stalls

--- 4-The thought that Jets aren't tested in slow flight [and slower= ] is false as well, all of these jets are fully tested before being signed off an= 'released' for production. All pilots in training then fly these maneuvers w= hile doing type training [in simulators which duplicate the tested results]. If y= ou think that once you get your Airline Transport License your done w/ stall/approach to stall training for the rest of your flying career, yo= ur mistaken.

 


 


= --Apple-Mail-FD5F0A81-FBA1-46E0-AB8B-1330B410F3A6--