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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 20, 2009 11:36 am Post subject: Autopilots vs. "The Right Stuff"

At 09:04 AM 7/20/2009, you wrote:

Good Morning 'Lectric Bob,



Interesting thoughts from Doctor Dee.



It brings me to question if my strong advocacy of the T&B over the TC 

might be some evidence of my personal conditioning.



It also leads me to think that maybe I am right in my feelings and 

that the quandary we find ourselves in when we get confused about 

which way is up is caused by that lack of consistency in our perceptions



Sooo  ....  I have already added another thing for me to worry about! <G>



    The debate for visual display of yaw rate and

    apparent center of the earth (gravity) as

    a flight instrument is only slightly related to

    the task of providing a practical automatic

    flight control system. For a simple yaw damper

    to work, it needs only numerical knowledge of

    turning rate about the yaw axis.



    However, given that the process of turning the airplane

    to a new heading BEGINS with a change in roll

    followed by a change in yaw rate. Doing the job

    smoothly with a single rate sensor required some

    knowledge of both roll (to anticipate a heading

    change) and yaw (to quantify the rate of change

    after the turn was established).



    While the T&B may well be best suited to recovering

    from an upset condition, the TC is best suited for

    avoiding that upset in the first place. I.e, Brittain

    could not have achieved the design goal without a

    carefully considered "pollution" of TB data.



Not sure where you were working at the time or how close you were to 

automatic flight, but I bet you know about how Beech competed with 

Mooney's PC.



    Only vaguely. I'll have to ask some of the grey-beards

    if they recall the system. I guess I could get on

    the computer and check service parts catalogs. I think

    Beech listed their A/P hardware in those books.



Beech installed a Century I (The folks who made it were called Edo 

Aire Mitchell at the time) Wing Leveler and my memory is that they 

called it the Constant Copilot. The main difference was that Beech 

provided an ON/OFF switch so the pilot could choose to use it or not.



My recollection is that Piper offered a similar unit, but I do not 

recall who made it for them or what they called it.



    I believe Piper had the Brittian system too but

    featured a valve in the vacuum supply line to

    shut if off if wanted. I think that valve was

    added to the Mooneys later.



Back to the Constant Copilot.



If the switch was left on, the wing leveler worked full time just 

like the Mooney PC. It could be easily over ridden without causing 

any damage to the unit and it was made inoperative by pressing an 

interrupter switch on the control wheel. Take your thumb off the 

switch button and the leveler took over.



We always told our customers to use it regularly.



Almost nobody did!



    Yeah, the "Right Stuff" syndrome. I guess it

    depends on what you use the airplane for and

    how you assess risk for the situations in which

    you fly. I enjoy flying. I enjoyed honing my

    under-the-hood skills. But when it was necessary

    to competently and smoothly manage a transition

    though IMC, I've never been adverse to calling

    up what ever support was available to reduce both

    sweat and risk.



    I've run the traps with some fellow techo-wiennies

    here in Wichita for a roll servo that contains

    a dedicated GPS receiver, canted roll/yaw rate

    sensor and a micro-controller that will "hold that

    GPS track" to plus/minus 1 degree. Controls would

    be limited to an on/off switch and bi-directional

    track increment buttons. Click one for each degree

    of track change. Hold button for standard rate turn.



    The servo would have a serial port that accepts

    commands for "new track to make good". The same

    line outputs system status. As a single installation,

    you install a servo, hook up an antenna, hook up

    14v and you're done. As a dual installation, there

    would be a "arbitrator box" that compares data

    to and from the pair of wing levelers with data from

    a panel mounted GPS and raises a warning flag if

    one of the systems mis-behaves. Each system is

    powered from a separate source.



    It's my belief that such a system would allow a

    pilot to comfortably enter a controlled airspace

    environment and comply with all ATC instructions

    with great precision, low risk and very low

    sweat factor . . . and never have to touch the

    stick. E.g. cluttering the panel with attitude

    displays would add nothing to the design goal.



    Bill of materials for the full-up system is under

    $200.  All I need is a 36 hour day and a relaxation

    of other duties!



    Bob. . .

BobsV35B(at)aol.com
Guest

Posted: Mon Jul 20, 2009 12:24 pm Post subject: Autopilots vs. "The Right Stuff"

Good Afternoon 'Lectric Bob,

  

 I totally agree with you that the canted gyro works better for a wing  leveler than does a T&B, but I do NOT feel it works well with we human  pilots. Too much conflict with our semi circular canal sensors. But I have  expanded on that thought here many times in the past.

  

 I would  love to see something new and modern that would replace the  T&B and the TC. Your thought on using a sequential GPS position seems to me  to have considerable merit.

  

 Happy Skies,

  

 Old Bob

 LL22

 Piper Pacer  N2858P

  

  In a message dated 7/20/2009 2:37:45 P.M. Central Daylight Time,  nuckolls.bob(at)aeroelectric.com writes:

  	  Quote: 	
		  Bill of    materials for the full-up system is under

    $200.  All I    need is a 36 hour day and a relaxation

    of other    duties!



    Bob. .  .



	


 What's for dinner tonight?  Find quick and easy dinner ideas for any occasion.

  [quote][b]

mprather(at)spro.net
Guest

Posted: Mon Jul 20, 2009 12:57 pm Post subject: Autopilots vs. "The Right Stuff"

Modern autopilots are remarkably better performers than their elder

parents..  The P3 Orion had an autopilot which had a component with a

limited operating life..  Crews would often hand fly en route to and from

their station in order to improve the odds that the autopilot would work

during a critical period.



My only personal experience with autopilots is in late 70's Archers which

I think had a rebadged Century III.  They do the job (track a nav source),

but sloppily.  They tend to wander heading a fair amount and if the rudder

trim isn't spot-on they can see-saw back and forth.  In a flight regime

with low indicated airspeed (climb or high altitude cruise) the increased

adverse yaw makes the ride somewhat unpleasant and is kind of distracting.

 Especially in an airplane with fairly strong roll-yaw coupling.  If that

were the state of the art for autopilots, I'd be much less excited about

having one.



My impression is that the modern autopilots are much, much better. 

Although, I did get a ride in the right seat of a PC12..  At cruise (in

the low FL's) in smooth air the airplane tended to slowly vary altitude

+/-100ft from the programmed value.  Seemed a bit odd in a brand new

(30TTSN) multi-million dollar machine.  Probably just needed a bit of

tuning.



Finally, pilots need to train like they fly, and fly like they train. 

Pilots need to let George fly enough so that they have confidence in "his"

abilities.

Regards,



Matt-



 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 09:04 AM 7/20/2009, you wrote:

 Good Morning 'Lectric Bob,



 Interesting thoughts from Doctor Dee.



 It brings me to question if my strong advocacy of the T&B over the TC

 might be some evidence of my personal conditioning.



 It also leads me to think that maybe I am right in my feelings and

 that the quandary we find ourselves in when we get confused about

 which way is up is caused by that lack of consistency in our perceptions



 Sooo  ....  I have already added another thing for me to worry about! <G>



     The debate for visual display of yaw rate and

     apparent center of the earth (gravity) as

     a flight instrument is only slightly related to


	


snip

jbr79r(at)yahoo.com
Guest

Posted: Mon Jul 20, 2009 1:25 pm Post subject: Autopilots vs. "The Right Stuff"

We have something better than T&B or TC.  It's call glass panels with pictorial displays that the mind doesn't have to do much to interpret  Strong visual information .

 

James Robinson

Glasair lll  N79R

Spanish Fork UT  U77

From: "BobsV35B(at)aol.com" <BobsV35B(at)aol.com>

To: aeroelectric-list(at)matronics.com

Sent: Monday, July 20, 2009 2:17:26 PM

Subject: Re: Autopilots vs. "The Right Stuff"



      Good Afternoon 'Lectric Bob,

  

 I totally agree with you that the canted gyro works better for a wing leveler than does a T&B, but I do NOT feel it works well with we human pilots. Too much conflict with our semi circular canal sensors. But I have expanded on that thought here many times in the past.

  

 I would  love to see something new and modern that would replace the T&B and the TC. Your thought on using a sequential GPS position seems to me to have considerable merit.

  

 Happy Skies,

  

 Old Bob

 LL22

 Piper Pacer  N2858P

  

  In a message dated 7/20/2009 2:37:45 P.M. Central Daylight Time,  nuckolls.bob(at)aeroelectric.com writes:

  	  Quote: 	
		  Bill of   materials for the full-up system is under

    $200.  All I   need is a 36 hour day and a relaxation

    of other   duties!



    Bob. . .



	




 What's for dinner tonight?  Find quick and easy dinner ideas for any occasion.

  [quote][b]

BobsV35B(at)aol.com
Guest

Posted: Mon Jul 20, 2009 3:18 pm Post subject: Autopilots vs. "The Right Stuff"

Good Evening James,

  

 I sure hope something works out along that line, but suitable reliability  and usability has not yet been demonstrated. 

  

 Glass is also way out of my price range at the present time. The TC and  T&B have been fairly economical in the past, though the prices have  skyrocketed in the last couple of years.  Do you figure on two glass units  to provide back up or are you willing to go with a single source of information?  I kinda like Jim Younkin's instrument for experimental aircraft. We who fly  certified antiques are not allowed to use Jim's stuff.

  

 Happy Skies,

  

 Old Bob

  

  In a message dated 7/20/2009 4:26:37 P.M. Central Daylight Time,  jbr79r(at)yahoo.com writes:

  	  Quote: 	
		  We have something better than T&B or TC.  It's call glass    panels with pictorial displays that the mind doesn't have to do much to    interpret  Strong visual information .

    

James Robinson

Glasair lll N79R

Spanish Fork UT    U77 	


 An Excellent21323041x1201367261/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=62%26bcd=JulyExcfooterNO62>See Yours in Just 2 Easy Steps!

  [quote][b]

Bruce(at)glasair.org
Guest

Posted: Mon Jul 20, 2009 3:36 pm Post subject: Autopilots vs. "The Right Stuff"

Hi Jim,  

   

It’s been proven time and time again that you’re better off using a backup system that uses a different method of operation when your panel goes dark.  

     

Bruce

 www.Glasair.org   

  

--

jbr79r(at)yahoo.com
Guest

Posted: Mon Jul 20, 2009 4:40 pm Post subject: Autopilots vs. "The Right Stuff"

I have the trutrak auto pilot and it has been very dependable.  Also the support has be very good.  I fly with 2 screen Cheltons with some round gauges as backup and a AOA.  I am all electric with a 2 alternator setup.  It definitely ups the ante however

 

James Robinson

Glasair lll  N79R

Spanish Fork UT  U77

From: "BobsV35B(at)aol.com" <BobsV35B(at)aol.com>

To: aeroelectric-list(at)matronics.com

Sent: Monday, July 20, 2009 5:15:07 PM

Subject: Re: Autopilots vs. "The Right Stuff"



      Good Evening James,

  

 I sure hope something works out along that line, but suitable reliability and usability has not yet been demonstrated. 

  

 Glass is also way out of my price range at the present time. The TC and T&B have been fairly economical in the past, though the prices have skyrocketed in the last couple of years.  Do you figure on two glass units to provide back up or are you willing to go with a single source of information? I kinda like Jim Younkin's instrument for experimental aircraft. We who fly certified antiques are not allowed to use Jim's stuff.

  

 Happy Skies,

  

  Old Bob

  

  In a message dated 7/20/2009 4:26:37 P.M. Central Daylight Time, jbr79r(at)yahoo.com writes:

  	  Quote: 	
		  We have something better than T&B or TC.  It's call glass   panels with pictorial displays that the mind doesn't have to do much to   interpret  Strong visual information .

    

James Robinson

Glasair lll N79R

Spanish Fork UT   U77 	




 [b]An [quote][b]

jbr79r(at)yahoo.com
Guest

Posted: Mon Jul 20, 2009 4:40 pm Post subject: Autopilots vs. "The Right Stuff"

I have backup round gauges and auto pilot and AOA to help me out

 

James Robinson

Glasair lll  N79R

Spanish Fork UT  U77

From: Bruce Gray <Bruce(at)Glasair.org>

To: aeroelectric-list(at)matronics.com

Sent: Monday, July 20, 2009 5:32:14 PM

Subject: RE: Autopilots vs. "The Right Stuff"



                              

Hi Jim,   

     

Itâ€™s been proven time and time again that youâ€™re better off using a backup system that uses a different method of operation when your panel goes dark.   

       

Bruce

 www.Glasair.org    

  

--

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 20, 2009 7:38 pm Post subject: Autopilots vs. "The Right Stuff"

At 03:17 PM 7/20/2009, you wrote:

  	  Quote: 	
		   Good Afternoon 'Lectric Bob,

  

 I totally agree with you that the canted gyro works better for a wing leveler than does a T&B, but I do NOT feel it works well with we human pilots. Too much conflict with our semi circular canal sensors. But I have expanded on that thought here many times in the past.

  

 I would  love to see something new and modern that would replace the T&B and the TC. Your thought on using a sequential GPS position seems to me to have considerable merit. 	


    Stabilization and control of the airframe is

    still based on interpretation of rotational

    rate values. The sensors are now all solid

    state as opposed to spinning up a rotor

    on bearings. The rate sensors have become

    so commonplace that simple versions are offered

    to augment pilot controls for flying model

    r/c helicopters . . . and they're just a

    few dollars.



  http://tinyurl.com/lcuqkc 



    Two more technologies have come forward to make

    the job easier and better. GPS and microprocessors.



    Our first autopilot for the MQM-107



  http://www.designation-systems.net/dusrm/m-107.html



    was totally analog. 741 op amps and fists full of

    transistors. The next autopilot was a TI 9900

    processor. All of a sudden, our calculating

    ability combined with differentiation (anticipation)

    made this bird fly even better yet. 



    We never got to put GPS on this bird but it went

    into other products.



  http://tinyurl.com/lhwmnp 



    The availability of ground track nav data opened

    the horizons for auto flight AND auto navigation.



    The thing that would be pretty cool with the products

    I described is access to the serial data ports.

    The stand-alone device would nicely steer an

    airplane. But anyone handy with byte thrashing

    could craft an auto-navigation application in the

    portable number cruncher of their choice.



 

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------



     [quote][b]

raymondj(at)frontiernet.n
Guest

Posted: Mon Jul 20, 2009 8:10 pm Post subject: Autopilots vs. "The Right Stuff"

I recall hearing that the solid state sensors (gyros) had a problem with 

  drift. Is this still an issue?



Raymond Julian

Kettle River, MN

"Hope for the best, but prepare for the worst"



Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   At 03:17 PM 7/20/2009, you wrote:

> Good Afternoon 'Lectric Bob,

>  

> I totally agree with you that the canted gyro works better for a wing 

> leveler than does a T&B, but I do NOT feel it works well with we human 

> pilots. Too much conflict with our semi circular canal sensors. But I 

> have expanded on that thought here many times in the past.

>  

> I would  love to see something new and modern that would replace the 

> T&B and the TC. Your thought on using a sequential GPS position seems 

> to me to have considerable merit.

 

    Stabilization and control of the airframe is

    still based on interpretation of rotational

    rate values. The sensors are now all solid

    state as opposed to spinning up a rotor

    on bearings. The rate sensors have become

    so commonplace that simple versions are offered

    to augment pilot controls for flying model

    r/c helicopters . . . and they're just a

    few dollars.

 

 * http://tinyurl.com/lcuqkc*

 

    Two more technologies have come forward to make

    the job easier and better. GPS and microprocessors.

 

    Our first autopilot for the MQM-107

 

 http://www.designation-systems.net/dusrm/m-107.html

 

    was totally analog. 741 op amps and fists full of

    transistors. The next autopilot was a TI 9900

    processor. All of a sudden, our calculating

    ability combined with differentiation (anticipation)

    made this bird fly even better yet.

 

    We never got to put GPS on this bird but it went

    into other products.

 

 * http://tinyurl.com/lhwmnp*

 

    The availability of ground track nav data opened

    the horizons for auto flight AND auto navigation.

 

    The thing that would be pretty cool with the products

    I described is access to the serial data ports.

    The stand-alone device would nicely steer an

    airplane. But anyone handy with byte thrashing

    could craft an auto-navigation application in the

    portable number cruncher of their choice.

 

        Bob . . .

 

         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

 

 *

 

 

 *

mjpereira68(at)gmail.com
Guest

Posted: Tue Jul 21, 2009 12:27 am Post subject: Autopilots vs. "The Right Stuff"

 	  Quote: 	
		  

 http://tinyurl.com/lcuqkc




	


The cheap ones like the above don't work that well (although it will

still make the tail human controllable during helicopter aerobatics).



The quality futaba products aren't that cheap.  The difference between

the quality and cheaper products are how much drift in yaw they allow

under normal circumstances and how that effect varies based on input

voltage variance and temperature variance and how well the gyro deals

with vibration.  The expensive ones perform better in other ways that

matter in a rc helicopter but aren't needed in a wing leveler

environment (which would be levels of magnitude less demanding).



If i'm not mistaken Futaba actually produces their own sensors which

implies to me that signal conditioning commercial off the shelf

sensors must not be easy in demanding situations.



Then again you talk about gps input so with proper software you could

continually calibrate what signal from the gyro means "zero yaw" (or

any other yaw rate).  The thing is if you're going to do that it might

just be as easy to buy a quality gps chipset and calculate for bank

angle based on ground speed and turning radius (like the Garmin 396

and later do on their instrument page).  Without the gps input or

alternately a  3-axis compass input it would be difficult to not have

the autopilot (using whatever sensors are in the cheaper rc heli

gyros) continually command a very slow (yet highly annoying) turn.



c'ya,

Michael

BobsV35B(at)aol.com
Guest

Posted: Tue Jul 21, 2009 5:14 am Post subject: Autopilots vs. "The Right Stuff"

Good Morning Michael,

  

 Great information for an old guy like me that is still struggling with Ohms  Law!

  

 May I interject a few thoughts though?

  

 This new technology is certain to provide us with excellent autopilots and  situational awareness instrumentation. The advancements in technology are mind  boggling. Anything we purchase becomes obsolete before the ink is dry on the  check.

  

 That is all to the good and I love to see it happening.

  

 Back to the world of application. 

  

 The first time Wilbur, Orville or Glenn had difficulty establishing their  reference to the natural horizon, folks realized that some instrumentation would  be required to allow safe flight when visibility was reduced.

  

 The principles of the gyroscope were well understood and it was not long  before various adaptations were applied to aircraft control.

  

 At the same time, the Wrights and other pioneers realized that there was  benefit to building aerodynamic stability into their flying machines. As an  aside, the Wrights had initially thought that the machine needed to be built  with almost neutral stability in order for it to be controllable. The reason  they never rebuilt the original Wright Flyer, but went on to another design is  because their flights on December 17, 1903 taught them that the Flyer was not  stable enough for practical flight.

  

 By the end of World War One, the concept of making the airplane dynamically  stable and using a gyroscope to tell the pilot he/she was turning was well  established. Monster ship's gyroscopes were too expensive and too heavy for  practical airborne use, but a simple gyroscope hooked to some sort of an  indicator that could tell the pilot the craft was turning was light weight and  cheap enough that it became common equipment.  Most of those units used a  needle of some sort to tell the pilot what was happening. Many of the ones  developed by European interests had the needle hinged at the top. Most that were  developed on our side of the pond had the needle hinged at the bottom.

  

 By using the Turn needle to keep any turning force to a minimum and by  learning the idiosyncrasies of Magnetic Compass precession during turns, it  became practical to fly in cloud. Not easy, but doable.

  

 By the end of  WW I the shape of future instrumentation was quite  evident.

  

 They had learned that if you stop the turn, you will survive!

  

 Since coordinated flight was found to be advantageous, a simple  inclinometer was added to the flight panel to display the degree of coordination  being used. By the beginning of WWII, most turn instruments had that ball  included within the same instrument case.

  

 Gyroscopes that showed an artificial horizon were developed, but they  tended to be very heavy, very expensive, very delicate and not at all reliable  if their mechanical limitations were exceeded.

  

 During the late twenties and early thirties, instrument flight became a  practical endeavor. The Turn and Bank was the main thing used to allow the  pilots to perceive a turning moment and the built in stability of the aircraft  was such that it was relatively easy to evaluate the pitch and speed of the  aircraft by the response of the airspeed indicator and the altimeter.

  

 Thus we had Needle, Ball, and Airspeed IFR flight.

  

 By the time WWII came along, the artificial horizons had gotten cheap  enough and light enough such that they were fitted to most airliners and many  larger military aircraft. Sure made for easier and smoother flight  operations.

  

 Notice that, thus far, we were still relying primarily on a human being to  supply the motion need to position the controls?

  

 Efforts had been made to build machinery that would perform that function,  but was not yet well developed.

  

 Since this dissertation is getting way too long for an avionics list, fast  forward to today. 

  

 We now have almost unlimited calculating capability and there seems to be  no reason why the human even needs to be involved other than as a mechanism  to monitor what the electrons are doing. Given sufficient computing power, there  is no doubt in my mind that it is relatively easy to make a machine that has a  lower failure rate than do we mere humans. 

  

 So, I guess the question is, how much do we want humans to be  involved?

  

 Happy Skies,

  

 Old Bob

 LL22

 Stearman N3977A

  

  In a message dated 7/21/2009 3:28:15 A.M. Central Daylight Time,  mjpereira68(at)gmail.com writes:

  	  Quote: 	
		  

Then    again you talk about gps input so with proper software you    could

continually calibrate what signal from the gyro means "zero yaw"    (or

any other yaw rate).  The thing is if you're going to do that it    might

just be as easy to buy a quality gps chipset and calculate for    bank

angle based on ground speed and turning radius (like the Garmin    396

and later do on their instrument page).  Without the gps input    or

alternately a  3-axis compass input it would be difficult to not    have

the autopilot (using whatever sensors are in the cheaper rc    heli

gyros) continually command a very slow (yet highly annoying)    turn.



c'ya,

Michael

	


 What's for dinner tonight?  Find quick and easy dinner ideas for any occasion.

  [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jul 21, 2009 5:23 am Post subject: Autopilots vs. "The Right Stuff"

At 03:05 AM 7/21/2009, you wrote:

 	  Quote: 	
		  

<mjpereira68(at)gmail.com>



 >

 > http://tinyurl.com/lcuqkc

 >



The cheap ones like the above don't work that well (although it will

still make the tail human controllable during helicopter aerobatics).


	


   The citation of this particular part was not intended to

   suggest suitability to any task, only to illustrate the

   advancements in micro-electronics for the sensing of physical

   phenomena. Certainly there are moderately priced, solid state

   rate sensors that may be better suited to the task of

   crafting a flight augmentation system for a manned aircraft.



   But even the best sensors have offset gain and temperature

   coefficient errors that must be considered as part of the

   overall error budget. The neat thing about teaming these devices

   with micro-controllers is the ability to compare sensor outputs

   with other, more stable data sources and deduce those errors

   for the purposes of reducing/eliminating their effects.



   For example, we could take the least expensive of

   rate sensors combined with a GPS receiver and artfully

   crafted software that would allow the autopilot to go through

   some gentle maneuvers, compare expected GPS data with real

   data and calculate new offset and gain values for the

   as-installed rate sensor. Tailoring an autopilot

   to a specific airframe and its installation is a tedious

   and exacting process. However, for the simple heading-hold

   wing leveler, a freshly installed system could be placed in

   a temporary calibration mode and flown at altitude while

   allowing the autopilot to wiggle the controls and deduce

   appropriate gain and offset values for ALL of the as-installed

   hardware. Once the calibration sequence is completed, a

   switch is moved from the CAL to the FLY position and the

   processor stores all the new values for operation.



   If the el-cheeso rate sensor exhibits some degree of

   long term drift, the CAL process can be repeated at

   the owner's convenience to trim up system performance

   at any time. Further, cross checking against GPS data,

   allows small values of drift to be deduced on-the-fly

   and accounted for. FAA rules for software qualification

   would make such conveniences very difficult in a TC aircraft.



   As I suggested in an earlier post, the availability

   and capability of inexpensive GPS engines, micro-controllers

   and low-cost rate sensors is head-and-shoulders above

   those components which were the best we knew how to do

   30 years ago.



        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jul 21, 2009 5:24 am Post subject: Autopilots vs. "The Right Stuff"

At 10:58 PM 7/20/2009, you wrote:

 	  Quote: 	
		  



I recall hearing that the solid state sensors (gyros) had a problem 

with  drift. Is this still an issue?


	


   You betcha! But it's slow and can be accommodated

   in software. See companion posting.

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

mjpereira68(at)GMAIL.COM
Guest

Posted: Tue Jul 21, 2009 6:22 am Post subject: Autopilots vs. "The Right Stuff"

On Tue, Jul 21, 2009 at 6:21 AM, Robert L. Nuckolls,

III<nuckolls.bob(at)aeroelectric.com> wrote:

 	  Quote: 	

 <nuckolls.bob(at)aeroelectric.com>

 At 03:05 AM 7/21/2009, you wrote:

>

> 

> <mjpereira68(at)gmail.com>

>

> >

> > http://tinyurl.com/lcuqkc

> >

>

> The cheap ones like the above don't work that well (although it will

> still make the tail human controllable during helicopter aerobatics).

  The citation of this particular part was not intended to

  suggest suitability to any task, only to illustrate the

  advancements in micro-electronics for the sensing of physical

  phenomena. Certainly there are moderately priced, solid state

  rate sensors that may be better suited to the task of

  crafting a flight augmentation system for a manned aircraft.

  But even the best sensors have offset gain and temperature

  coefficient errors that must be considered as part of the

  overall error budget. The neat thing about teaming these devices

  with micro-controllers is the ability to compare sensor outputs

  with other, more stable data sources and deduce those errors

  for the purposes of reducing/eliminating their effects.

  For example, we could take the least expensive of

  rate sensors combined with a GPS receiver and artfully

  crafted software that would allow the autopilot to go through

  some gentle maneuvers, compare expected GPS data with real

  data and calculate new offset and gain values for the

  as-installed rate sensor. Tailoring an autopilot

  to a specific airframe and its installation is a tedious

  and exacting process. However, for the simple heading-hold

  wing leveler, a freshly installed system could be placed in

  a temporary calibration mode and flown at altitude while

  allowing the autopilot to wiggle the controls and deduce

  appropriate gain and offset values for ALL of the as-installed

  hardware. Once the calibration sequence is completed, a

  switch is moved from the CAL to the FLY position and the

  processor stores all the new values for operation.

Oh i agree with everything you've said. I think you'd have to manage

without a specific calibration routine however, it's something that

would have to run constantly (and that's assuming the quality

gyro/rate sensor).

 	  Quote: 	

  If the el-cheeso rate sensor exhibits some degree of

  long term drift, the CAL process can be repeated at

  the owner's convenience to trim up system performance

  at any time. Further, cross checking against GPS data,

  allows small values of drift to be deduced on-the-fly

  and accounted for. FAA rules for software qualification

  would make such conveniences very difficult in a TC aircraft.

The thing with the cheesy sensors as applied to the rc heli gyros is

the drift varies from minute to minute requiring constant trim

adjustments to the tail channel so it'll sit (relatively) still while

the stick is at neutral. Now, the problem could be more related to

crummy software than the sensor itself. No way to know in this kind of

black box situation what components are generating what percentage of

the total error.

Whatever the case is with the cheesy gyros, futaba has it nailed with

their more expensive stuff.  Their tech is probably good enough for

the cockpit (at least in general aviation). The drift errors are

small, that has to make writing the calibration software easier.  They

probably aren't crazy enough to license it to that market considering

the market size/liability issues though.

 	  Quote: 	
		    As I suggested in an earlier post, the availability

  and capability of inexpensive GPS engines, micro-controllers

  and low-cost rate sensors is head-and-shoulders above

  those components which were the best we knew how to do

  30 years ago.

So i'm curious. I've read a bit about 3-axis electronic compasses

(basically the 3d allows the device to automatically compensate for

magnetic tilt errors). If these devices are accurate enough and update

fast enough, could one of these alone drive a simple wing leveler ?

ie. change in heading divided by time equals rate of turn, etc.  Well

actually, I guess it would act nuts if you were operating close enough

to one of the magnetic poles, nevermind. lol.

c'ya,

Michael

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Jul 21, 2009 7:30 am Post subject: Autopilots vs. "The Right Stuff"

 	  Quote: 	
		  

Oh i agree with everything you've said. I think you'd have to manage

without a specific calibration routine however, it's something that

would have to run constantly (and that's assuming the quality

gyro/rate sensor).


	


   Sure, with the GPS engine data we can resolve slow, short term

   drifts and compensate on-the-fly. The larger calibration

   corrections would probably be a one-time thing that would

   wash out initial offset, gains and mechanism transfer

   functions.

 	  Quote: 	
		  The thing with the cheesy sensors as applied to the rc heli gyros is

the drift varies from minute to minute requiring constant trim

adjustments to the tail channel so it'll sit (relatively) still while

the stick is at neutral. Now, the problem could be more related to

crummy software than the sensor itself. No way to know in this kind of

black box situation what components are generating what percentage of

the total error.


	


    We would probably not choose to get THAT cheesy. There's a host

    of rate sensors offered by the micro-machined chip manufacturers

    with very useable drift characteristics.



 	  Quote: 	
		  Whatever the case is with the cheesy gyros, futaba has it nailed with

their more expensive stuff.  Their tech is probably good enough for

the cockpit (at least in general aviation). The drift errors are

small, that has to make writing the calibration software easier.  They

probably aren't crazy enough to license it to that market considering

the market size/liability issues though.


	


    Wouldn't seek a "license" . . . there are plenty of

    commercial, off-the-shelf devices to choose from that

    have no more liability for airplanes falling out of the

    sky than do the nail manufacturer's have to shoulder for

    houses falling down.

 	  Quote: 	
		   >  As I suggested in an earlier post, the availability

 >  and capability of inexpensive GPS engines, micro-controllers

 >  and low-cost rate sensors is head-and-shoulders above

 >  those components which were the best we knew how to do

 >  30 years ago.



So i'm curious. I've read a bit about 3-axis electronic compasses

(basically the 3d allows the device to automatically compensate for

magnetic tilt errors). If these devices are accurate enough and update

fast enough, could one of these alone drive a simple wing leveler ?

ie. change in heading divided by time equals rate of turn, etc.  Well

actually, I guess it would act nuts if you were operating close enough

to one of the magnetic poles, nevermind. lol.


	


    They're interesting devices and we looked at them several

    times at the Beech/RAC Targets division. Problem is that

    there are 3 conditions of orientation where these devices

    fall out of bed. That's when any one of the three axes are

    exactly aligned with earth magnetic flux lines. Under that

    condition, the other two axes see the same data no matter

    how the device is rotated about that axis. While these

    may be transient conditions, they offered enough risk to

    operation of the fully aerobatic target that we rejected

    their incorporation into the product.



    It may be that one could use them with more confidence

    where the design goal is not to recover from an unusual attitude

    but to keep from getting into an unusual attitude.



    Bob . . .

skywagon

Joined: 11 Feb 2006
Posts: 184

Posted: Tue Jul 21, 2009 7:43 am Post subject: Autopilots vs. "The Right Stuff"

Bob,

  

 Great review......

 Dave

 [quote]   ---

jaybannist(at)cs.com
Guest

Posted: Tue Jul 21, 2009 8:48 am Post subject: Autopilots vs. "The Right Stuff"

Yes, with the wondrous capabilities and reliability of today's computer controlled machines, be assured that nothing can go wrong...go wrong...go wrong....go........

 

 I seem to recall reading about several accidents caused by the erroneous actions of computer controlled servo systems; actions that couldn't be detected nor corrected by the pilots.  Admittedly, these were the result of faulty assumptions being built into the computer's database by humans.  I guess it comes down to "who (or what) do you trust?"

 

 Jay

 

   

 

   

 

 --

echristley(at)nc.rr.com
Guest

Posted: Tue Jul 21, 2009 5:14 pm Post subject: Autopilots vs. "The Right Stuff"

BobsV35B(at)aol.com wrote:

 	  Quote: 	
		   Good Morning Michael,

  

 Great information for an old guy like me that is still struggling with Ohms 

  Law!

  

 May I interject a few thoughts though?

  

 This new technology is certain to provide us with excellent autopilots and  

 situational awareness instrumentation. The advancements in technology are 

 mind  boggling. Anything we purchase becomes obsolete before the ink is dry 

 on the  check.

  

   

You still write checks?  Don't you know that technology have made them 
	


obsolete?  8*)



<snip>

 	  Quote: 	
		    

 So, I guess the question is, how much do we want humans to be  involved?

   

I didn't get a pilot's license so that a machine could fly me around. 8*)
	




-- 



http://www.ernest.isa-geek.org

BobsV35B(at)aol.com
Guest

Posted: Tue Jul 21, 2009 5:43 pm Post subject: Autopilots vs. "The Right Stuff"

Good Evening Ernest,

  

 May I take it from that statement that you prefer a Boeing over an  Airbus?

  

 I repeat: The question is, how much do we want humans to be   involved?

  

 Happy Skies,

  

 Old Bob

  

  In a message dated 7/21/2009 8:16:03 P.M. Central Daylight Time,  echristley(at)nc.rr.com writes:

  	  Quote: 	
		  I didn't    get a pilot's license so that a machine could fly me around.  8*)



	


 What's for dinner tonight?  Find quick and easy dinner ideas for any occasion.

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