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Blanking Effect

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wampam

Joined: 20 Oct 2008
Posts: 49

Posted: Mon Oct 20, 2008 8:30 am Post subject: Blanking Effect

Can anyone describe to me 'blanking effect'?  Has anyone had this problem with their lightning?  Seems that my lightning has no pitch control during takeoff (attempting).

N1BZRich(at)AOL.COM
Guest

Posted: Mon Oct 20, 2008 9:19 am Post subject: Blanking Effect

In a message dated 10/20/2008 12:31:58 P.M. Eastern Daylight Time,  walt.mefford(at)garmin.com writes:

  	  Quote: 	
		  Can    anyone describe to me 'blanking effect'?  Has anyone had this problem    with their lightning?  Seems that my lightning has no pitch control    during takeoff (attempting).

	


 

 Walt,

     We really need to know more about what you are  experiencing.  I really doubt that you are having the classic  "blanking effect" on takeoff since so many other Lightnings have had no problems  during that flight regime.  The most common (although it really isn't  common) type of blanking effect is on an airplane with aft fuselage nacelle  mounted engines that are able to block airflow to the tail (elevator) during  high AOA maneuvering.  This has been known to cause deep stalls that have  been unrecoverable.  

     As far as any type of blanking effect in flying the  Lightning I have seen (actually felt) a very slight situation that I would  describe as blanking effect on only one airplane, and that was the Hybrid  Lightning (Esqual fuselage with the first set of Lightning wings).  That  airplane had flaps that would go down 45 degrees and when doing a full flap,  full rudder deflection slip, I would feel the elevator be blanked for just a  second then the nose would drop and you would regain elevator  effectiveness.  Of course it would do it again unless you let off some of  the rudder or elevator throw.  I have NOT seen this on any of the  production Lightning kits, as Nick has limited the flap down movement to 40  degrees.  And you really don't need 40 degrees on a normal Lightning  landing.  

     As to your situation, we really need more info to  analyze what you might be experiencing:

 -  First, have you insured your elevator up travel is what is call for  in the plans?  Some have miss-adjusted their elevator geometry set up and  initially did not have all the up travel that is called for.  The airplane  still will rotate, but at a higher airspeed.  

 - Second, what speeds are you talking about?

 - What is your takeoff technique?  Are you using 10 degrees of  flaps?  Do you have the bungee trim system or the new trim tab?

 - Oh yes, what is your CG location?

 By knowing the above, I am sure we can figure out what you are  experiencing.

 Blue Skies,

 Buz



New MapQuest Local shows what's happening at your destination. Dining, Movies, Events, News & moreol?redir=http://local.mapquest.com/?ncid=emlcntnew00000002">Try it out! 

  [quote][b]

Kayberg(at)AOL.COM
Guest

Posted: Mon Oct 20, 2008 9:32 am Post subject: Blanking Effect

In a message dated 10/20/2008 12:31:58 P.M. Eastern Daylight Time,  walt.mefford(at)garmin.com writes:

  	  Quote: 	
		  

Can    anyone describe to me 'blanking effect'?  Has anyone had this problem    with their lightning?  Seems that my lightning has no pitch control    during takeoff (attempting).

	


 

  

  

 I think a little more information is necessary to get a good response  to this question.

  

 The short answer is that you are not going fast enough if you dont have  pitch authority.   The blanking that was suggested (and debated) has  to do with full flaps and  limited elevators just before a stall  landing.

  

 If you are doing high speed taxi, you should not have full flaps  deployed.

  

 Unless you are at a very short field,  the first flight should be with  no flaps at all.

  

 I usually caution people not to do much high speed taxi.    Definitely DO NOT do "crow hops"

  

 You cant get a Lightning far enough out of rig to lose control if you just  line up the trailing edge and be sure the ailerons point up when you move the  stick toward them, so just GO FOR IT!

  

 But you should explain further.

  

  

 Doug Koenigsberg

  [quote][b]

wampam

Joined: 20 Oct 2008
Posts: 49

Posted: Mon Oct 20, 2008 9:40 am Post subject: Blanking Effect

-Buz  

   

I am about 1200 miles from where the plane is and most of the information I have is second hand.  Here is what I know so far.  

   

·         The CG has been checked and is well within limits under the current configuration - fuel (30gal), pilot (170lbs) and no baggage. – 1143lbs:CG 31.8”  

·         Engine power is OK and the plane is accelerating to well above rotation speed.  

·         The nose wheel will not lift with full back pressure at any speed thus far.  

·         The test pilot indicated that it felt as though the stabilizer was not even connected (no back pressure).  

o        All connections have been checked and are functional.  

   

   

Walt Mefford   

   

   

         

  

From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of N1BZRich(at)aol.com

 Sent: Monday, October 20, 2008 10:20 AM

 To: lightning-list(at)matronics.com

 Subject: Re: Lightning-List: Blanking Effect  

  

       

In a message dated 10/20/2008 12:31:58 P.M. Eastern Daylight Time, walt.mefford(at)garmin.com writes:  

   	  Quote: 	
		    

Can anyone describe to me 'blanking effect'?  Has anyone had this problem with their lightning?  Seems that my lightning has no pitch control during takeoff (attempting).  	
  

    

Walt,  

    

    We really need to know more about what you are experiencing.  I really doubt that you are having the classic "blanking effect" on takeoff since so many other Lightnings have had no problems during that flight regime.  The most common (although it really isn't common) type of blanking effect is on an airplane with aft fuselage nacelle mounted engines that are able to block airflow to the tail (elevator) during high AOA maneuvering.  This has been known to cause deep stalls that have been unrecoverable.    

    

    As far as any type of blanking effect in flying the Lightning I have seen (actually felt) a very slight situation that I would describe as blanking effect on only one airplane, and that was the Hybrid Lightning (Esqual fuselage with the first set of Lightning wings).  That airplane had flaps that would go down 45 degrees and when doing a full flap, full rudder deflection slip, I would feel the elevator be blanked for just a second then the nose would drop and you would regain elevator effectiveness.  Of course it would do it again unless you let off some of the rudder or elevator throw.  I have NOT seen this on any of the production Lightning kits, as Nick has limited the flap down movement to 40 degrees.  And you really don't need 40 degrees on a normal Lightning landing.    

    

    As to your situation, we really need more info to analyze what you might be experiencing:  

    

-  First, have you insured your elevator up travel is what is call for in the plans?  Some have miss-adjusted their elevator geometry set up and initially did not have all the up travel that is called for.  The airplane still will rotate, but at a higher airspeed.    

    

- Second, what speeds are you talking about?  

    

- What is your takeoff technique?  Are you using 10 degrees of flaps?  Do you have the bungee trim system or the new trim tab?  

    

- Oh yes, what is your CG location?  

    

By knowing the above, I am sure we can figure out what you are experiencing.  

    

Blue Skies,  

    

Buz  

  



 

         

  

New MapQuest Local shows what's happening at your destination. Dining, Movies, Events, News & moreol?redir=http://local.mapquest.com/?ncid=emlcntnew00000002">Try it out!   

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wampam

Joined: 20 Oct 2008
Posts: 49

Posted: Mon Oct 20, 2008 9:58 am Post subject: Blanking Effect

Oops, that is 1191lbs – 32.06”  

   

WM  

         

  

From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of N1BZRich(at)aol.com

 Sent: Monday, October 20, 2008 10:20 AM

 To: lightning-list(at)matronics.com

 Subject: Re: Lightning-List: Blanking Effect  

  

       

In a message dated 10/20/2008 12:31:58 P.M. Eastern Daylight Time, walt.mefford(at)garmin.com writes:  

   	  Quote: 	
		    

Can anyone describe to me 'blanking effect'?  Has anyone had this problem with their lightning?  Seems that my lightning has no pitch control during takeoff (attempting).  	
  

    

Walt,  

    

    We really need to know more about what you are experiencing.  I really doubt that you are having the classic "blanking effect" on takeoff since so many other Lightnings have had no problems during that flight regime.  The most common (although it really isn't common) type of blanking effect is on an airplane with aft fuselage nacelle mounted engines that are able to block airflow to the tail (elevator) during high AOA maneuvering.  This has been known to cause deep stalls that have been unrecoverable.    

    

    As far as any type of blanking effect in flying the Lightning I have seen (actually felt) a very slight situation that I would describe as blanking effect on only one airplane, and that was the Hybrid Lightning (Esqual fuselage with the first set of Lightning wings).  That airplane had flaps that would go down 45 degrees and when doing a full flap, full rudder deflection slip, I would feel the elevator be blanked for just a second then the nose would drop and you would regain elevator effectiveness.  Of course it would do it again unless you let off some of the rudder or elevator throw.  I have NOT seen this on any of the production Lightning kits, as Nick has limited the flap down movement to 40 degrees.  And you really don't need 40 degrees on a normal Lightning landing.    

    

    As to your situation, we really need more info to analyze what you might be experiencing:  

    

-  First, have you insured your elevator up travel is what is call for in the plans?  Some have miss-adjusted their elevator geometry set up and initially did not have all the up travel that is called for.  The airplane still will rotate, but at a higher airspeed.    

    

- Second, what speeds are you talking about?  

    

- What is your takeoff technique?  Are you using 10 degrees of flaps?  Do you have the bungee trim system or the new trim tab?  

    

- Oh yes, what is your CG location?  

    

By knowing the above, I am sure we can figure out what you are experiencing.  

    

Blue Skies,  

    

Buz  

  



 

         

  

New MapQuest Local shows what's happening at your destination. Dining, Movies, Events, News & moreol?redir=http://local.mapquest.com/?ncid=emlcntnew00000002">Try it out!   

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Kayberg(at)aol.com
Guest

Posted: Mon Oct 20, 2008 10:01 am Post subject: Blanking Effect

What about the flaps position?

  

 Doug

  

  

  

 In a message dated 10/20/2008 1:41:02 P.M. Eastern Daylight Time,  walt.mefford(at)garmin.com writes:

  	  Quote: 	
		     

-Buz   

    

I am about 1200 miles    from where the plane is and most of the information I have is second    hand.  Here is what I know so far.   

    

Â·            The CG has been    checked and is well within limits under the current configuration - fuel    (30gal), pilot (170lbs) and no baggage. â€“ 1143lbs:CG 31.8â€   

Â·            Engine power is OK    and the plane is accelerating to well above rotation speed.   

Â·            The nose wheel will    not lift with full back pressure at any speed thus far.   

Â·            The test pilot    indicated that it felt as though the stabilizer was not even connected (no    back pressure).   

o           All connections have    been checked and are functional.   

    

    

Walt Mefford       

  	


 

  

  [quote][b]

wampam

Joined: 20 Oct 2008
Posts: 49

Posted: Mon Oct 20, 2008 10:21 am Post subject: Blanking Effect

I assume they were in the normal takeoff position of 10 degrees.  I will have to check.  

   

-Walt   

         

  

From: owner-lightning-list-server(at)matronics.com [mailto:owner-lightning-list-server(at)matronics.com] On Behalf Of Kayberg(at)aol.com

 Sent: Monday, October 20, 2008 11:00 AM

 To: lightning-list(at)matronics.com

 Subject: Re: Lightning-List: Blanking Effect  

  

       

What about the flaps position?  

    

   

    

Doug  

    

   

    

   

    

   

    

In a message dated 10/20/2008 1:41:02 P.M. Eastern Daylight Time, walt.mefford(at)garmin.com writes:  

   	  Quote: 	
		    

-Buz  

   

I am about 1200 miles from where the plane is and most of the information I have is second hand.  Here is what I know so far.  

   

·         The CG has been checked and is well within limits under the current configuration - fuel (30gal), pilot (170lbs) and no baggage. – 1143lbs:CG 31.8”  

·         Engine power is OK and the plane is accelerating to well above rotation speed.  

·         The nose wheel will not lift with full back pressure at any speed thus far.  

·         The test pilot indicated that it felt as though the stabilizer was not even connected (no back pressure).  

o        All connections have been checked and are functional.  

   

   

Walt Mefford   

   	
  

    

   

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N1BZRich(at)AOL.COM
Guest

Posted: Mon Oct 20, 2008 3:39 pm Post subject: Blanking Effect

In a message dated 10/20/2008 1:41:02 P.M. Eastern Daylight Time,  walt.mefford(at)garmin.com writes:

  

 Â·          The CG has been checked  and is well within limits under the current configuration - fuel (30gal), pilot  (170lbs) and no baggage. â€“ 1143lbs:CG  31.8â€                                 

 Â·          Engine power is OK and  the plane is accelerating to well above rotation  speed.

 Â·          The nose wheel will not  lift with full back pressure at any speed thus far.

 Â·          The test pilot  indicated that it felt as though the stabilizer was not even connected (no back  pressure).

 o         All connections have  been checked and are functional.

  

 Walt,

     The  first thing to check is that you actually do have the proper amount of up  elevator travel with full back stick.  Several Lightnings have  been assembled with incorrect pitch geometry and they did not have full up  elevator travel.  In at least one case, the aircraft flew that way for some  time.  

     Has  the test pilot flown a Lightning before?  If not, what are they used to  flying?  What speed has he/she achieved on takeoff roll?  Does the  acceleration feel normal?  What prop do you have?  Do you still have  the bungee trim system?  Has the test pilot flown an aircraft with a bungee  trim system?  If so, is the bungee trim system set so that sitting on the  ground with full nose down trim, the elevator is down from neutral (at least a  little down from neutral)?  

     Where  is you aircraft located?  

 Buz



New MapQuest Local shows what's happening at your destination. Dining, Movies, Events, News & more. Try it out!

N1BZRich(at)AOL.COM
Guest

Posted: Mon Oct 20, 2008 4:05 pm Post subject: Blanking Effect

In a message dated 10/20/2008 1:33:50 P.M. Eastern Daylight Time,  Kayberg(at)aol.com writes:

  	  Quote: 	
		     The short answer is that you are not going fast enough if you dont have    pitch authority.   The blanking that was suggested (and debated) has    to do with full flaps and  limited elevators just before a stall    landing.

    

   Unless you are at a very short field,  the first flight should be    with no flaps at all.

	


 

 Doug,

     I generally agree with your "short answer" comment  that the airplane is not going fast enough to get pitch authority.   However, I am not familiar with "blanking" being suggested (and debated) that  had to do with full flaps and limited elevator just before a stall  landing.  What are we talking about here?  The basic design of the  Lightning (elevator not high above the thrust line and flaps limited to 40  degrees full down) will prevent any blanking of the elevator certainly up to and  at the stall angle of attack.  In fact with flaps down, you are much  further from even getting close to this situation than you are with flaps  up.  Remember what the Lightning does as you lower flaps - the nose goes  down.  And I have not idea what is meant by "limited elevators".   

     I also don't totally agree that the first flight  should be with no flaps at all.  For the first flight in a Lightning,  during the "near stall investigation" portion, I recommend you accomplish the  yaw, roll, pitch and trim investigation between speeds of 85 to 65 mph, clean,  then at 10 degree flaps, then at 20 degrees, and then at 30 degrees.  Some  people even take the bottom end of the speed down to 60 mph and that would work  well with the new tips and still keep you above the predicted clean stall  speed.  Of course if any of these step by step objectives indicate any  problems, stop at that point and make that first landing at the previous   setting.  This is kind of what is recommended in the FAA  Advisory  Circular 90-89 (I hope I am remembering that number right.)

 Buz



New MapQuest Local shows what's happening at your destination. Dining, Movies, Events, News & moreol?redir=http://local.mapquest.com/?ncid=emlcntnew00000002">Try it out! 

  [quote][b]

dashvii(at)hotmail.com
Guest

Posted: Mon Oct 20, 2008 4:18 pm Post subject: Blanking Effect

I remember encountering this on both the Frankensqual and one of the Jabiru's.  When I did it with the Jabiru it kind of surprised me.  I did a pretty agressive slip with full rudder and when I got there the nose just went down.  I had full flaps in there.  I knew that I didn't stall the plane C had plenty of speed.  I did what they taught me and undid what I had done.  The Jabiru leaves rudder in until you manually take it back out so you see where that could get kind of dicey.  I went around to think about it and was able to replicate it at a higher altitude.  I came back and told Ben what I thought was happening and he told me that I wasn't supposed to do that.  I believe the Cessna 172 might be the same on the models that have the 40 degrees of flaps.  The Cessna Cardinal has one of the famous stories of blanketing which required a fix.  The plane was blanking and loosing elevator authority on final right before touchdown making for dinged props and nose gear.  The fix was to put a slot in the leading edge of the horizontal stab.  Having said that C you're not getting blanking in the Lightning.  Something isn't right.  My first guess would be as has been suggested C not full elevator travel.  Brian W.

  From: N1BZRich(at)aol.com

Date: Mon C 20 Oct 2008 20:03:57 -0400

Subject: Re: Blanking Effect

To: lightning-list(at)matronics.com

   In a message dated 10/20/2008 1:33:50 P.M. Eastern Daylight Time C Kayberg(at)aol.com writes:

  	  Quote: 	
		   The short answer is that you are not going fast enough if you dont have pitch authority.   The blanking that was suggested (and debated) has to do with full flaps and  limited elevators just before a stall landing.

 Unless you are at a very short field C  the first flight should be with no flaps at all.

 Doug C

     I generally agree with your "short answer" comment that the airplane is not going fast enough to get pitch authority.  However C I am not familiar with "blanking" being suggested (and debated) that had to do with full flaps and limited elevator just before a stall landing.  What are we talking about here?  The basic design of the Lightning (elevator not high above the thrust line and flaps limited to 40 degrees full down) will prevent any blanking of the elevator certainly up to and at the stall angle of attack.  In fact with flaps down C you are much further from even getting close to this situation than you are with flaps up.  Remember what the Lightning does as you lower flaps - the nose goes down.  And I have not idea what is meant by "limited elevators".  

     I also don't totally agree that the first flight should be with no flaps at all.  For the first flight in a Lightning C during the "near stall investigation" portion C I recommend you accomplish the yaw C roll C pitch and trim investigation between speeds of 85 to 65 mph C clean C then at 10 degree flaps C then at 20 degrees C and then at 30 degrees.  Some people even take the bottom end of the speed down to 60 mph and that would work well with the new tips and still keep you above the predicted clean stall speed.  Of course if any of these step by step objectives indicate any problems C stop at that point and make that first landing at the previous  setting.  This is kind of what is recommended in the FAA  Advisory Circular 90-89 (I hope I am remembering that number right.)

 Buz

   New MapQuest Local shows what's happening at your destination. Dining C Movies C Events C News & moreol?redir=http://local.mapquest.com/?ncid=emlcntnew00000002">Try it out! 

 	  Quote: 	

st" target=_blank>http://www.matronics.com/Navigator?Lightning-List

ttp://forums.matronics.com

=_blank>http://www.matronics.com/contribution

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ryan(at)greenlandings.com
Guest

Posted: Mon Oct 20, 2008 4:37 pm Post subject: Blanking Effect

Walt,If I am not mistaken your aircraft is at Greg Hobbs airport. I would assume that the up elevator is in the proximity of 30 deg or so. Down elevator should be just slightly more the 10, but not more than 15. These numbers should give good authority at about 30-35 mph then allowing the aircraft to rotate at 45-50.Also I would check to make sure that the elevator control horn is not obstructed and hitting the rudder in the full up position.Ryan GrossGreen Landings Flight Center

Sent from my BlackBerry® smartphone with SprintSpeed

From:  Brian Whittingham <dashvii(at)hotmail.com>

Date: Mon, 20 Oct 2008 19:18:09 -0500

To: <lightning-list(at)matronics.com>

Subject: RE: Lightning-List: Blanking Effect

 I remember encountering this on both the Frankensqual and one of the Jabiru= 's.&nbsp=3B When I did it with the Jabiru it kind of surprised me.&nbsp=3B = I did a pretty agressive slip with full rudder and when I got there the nos= e just went down.&nbsp=3B I had full flaps in there.&nbsp=3B I knew that I = didn't stall the plane=2C had plenty of speed.&nbsp=3B I did what they taug= ht me and undid what I had done.&nbsp=3B The Jabiru leaves rudder in until = you manually take it back out so you see where that could get kind of dicey= .&nbsp=3B I went around to think about it and was able to replicate it at a=  higher altitude.&nbsp=3B I came back and told Ben what I thought was happe= ning and he told me that I wasn't supposed to do that.&nbsp=3B I believe th= e Cessna 172 might be the same on the models that have the 40 degrees of fl= aps.&nbsp=3B The Cessna Cardinal has one of the famous stories of blanketin= g which required a fix.&nbsp=3B The plane was blanking and loosing elevator=  authority on final right before touchdown making for dinged props and nose=  gear.&nbsp=3B The fix was to put a slot in the leading edge of the horizon= tal stab.&nbsp=3B Having said that=2C you're not getting blanking in the Li= ghtning.&nbsp=3B Something isn't right.&nbsp=3B My first guess would be as = has been suggested=2C not full elevator travel.&nbsp=3B Brian W.

 From: N1BZRich(at)aol.com

Date: Mon=2C 20 Oct 2008 20:03:57 -0400

Subjec= t: Re: Lightning-List: Blanking Effect

To: lightning-list(at)matronics.com<= BR>

In a message dated 10/20/2008 1:33:50 P.M. Eastern Daylight Time=2C Ka= yberg(at)aol.com writes:

 	  Quote: 	
		  The short answer is that you are not going fast enough if you dont hav= e pitch authority.&nbsp=3B&nbsp=3B The blanking that was suggested (and deb= ated) has to do with full flaps and&nbsp=3B limited elevators just before a=  stall landing.

&nbsp=3B

Unless you are at a very short field=2C&nbsp=3B the first flight shoul= d be with no flaps at all.

Doug=2C

&nbsp=3B&nbsp=3B&nbsp=3B&nbsp=3BI generally agree with your "short ans= wer" comment that the airplane is not going fast enough to get pitch author= ity.&nbsp=3B However=2C I am not familiar with "blanking" being suggested (= and debated) that had to do with full flaps and limited elevator just befor= e a stall landing.&nbsp=3B What are we talking about here?&nbsp=3B The basi= c design of the Lightning (elevator not high above the thrust line and flap= s limited to 40 degrees full down) will prevent any blanking of the elevato= r certainly up to and at the stall angle of attack.&nbsp=3B In fact with fl= aps down=2C you are much further from even getting close to this situation = than you are with flaps up.&nbsp=3B Remember what the Lightning does as you=  lower flaps - the nose goes down.&nbsp=3B And I have not idea what is mean= t by "limited elevators".&nbsp=3B 

&nbsp=3B&nbsp=3B&nbsp=3B&nbsp=3BI also don't totally agree that the fi= rst flight should be with no flaps at all.&nbsp=3B&nbsp=3BFor the first fli= ght in a Lightning=2C during the "near stall investigation" portion=2C I re= commend you accomplish the yaw=2C roll=2C pitch and trim investigation betw= een speeds of 85 to 65 mph=2C clean=2C then at 10 degree flaps=2C then at 2= 0 degrees=2C and then at 30 degrees.&nbsp=3B Some people even take the bott= om end of the speed down to 60 mph and that would work well with the new ti= ps and still keep you above the predicted clean stall speed.&nbsp=3B Of cou= rse if any of these&nbsp=3Bstep by step objectives indicate any problems=2C=  stop at that point and make that first landing at the previous&nbsp=3B set= ting.&nbsp=3B This is kind of what is recommended in the FAA&nbsp=3B Adviso= ry Circular 90-89 (I hope I am remembering that number right.)

Buz

 New MapQuest Local shows what's happening at your destination. Dinin= g=2C Movies=2C Events=2C News &amp=3B moreol?redir=3Dhttp://local.mapquest.= com/?ncid=3Demlcntnew00000002"&gt=3BTry it out! 

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Kayberg(at)AOL.COM
Guest

Posted: Tue Oct 21, 2008 3:38 am Post subject: Blanking Effect

Buz,

  

 I was suggesting a flaps-up takeoff only.  It is easy to rig the plane  so flaps and ailerons are all even. If you take off in that configuration, then  you should not have any serious wing drops.  Of course you would then test  the flaps  while exploring slowflight and perhaps approaches to  stalls.  You can make rigging adjustments later.

  

 It was the comment of some that they "ran out of elevator" on landing and  blamed "blanking".  I dont know if that is really the story or  not.   There are several possible causes including poor  piloting.   Sometimes there is a point in landing a Lightning where  you have full back stick, full flaps, nose up position and you simply must wait  for the touchdown.  The nose doesn't pitch down, which rules out the  "blanking".   But you can have a sense that you have no control for a  millisecond.

  

 Doug

  

  

  

 In a message dated 10/20/2008 8:06:18 P.M. Eastern Daylight Time,  N1BZRich(at)aol.com writes:

  	  Quote: 	
		     Doug,

       I generally agree with your "short answer"    comment that the airplane is not going fast enough to get pitch    authority.  However, I am not familiar with "blanking" being suggested    (and debated) that had to do with full flaps and limited elevator just before    a stall landing.  What are we talking about here?  The basic design    of the Lightning (elevator not high above the thrust line and flaps limited to    40 degrees full down) will prevent any blanking of the elevator certainly up    to and at the stall angle of attack.  In fact with flaps down, you are    much further from even getting close to this situation than you are with flaps    up.  Remember what the Lightning does as you lower flaps - the nose goes    down.  And I have not idea what is meant by "limited elevators".     

       I also don't totally agree that the first flight    should be with no flaps at all.  For the first flight in a    Lightning, during the "near stall investigation" portion, I recommend you    accomplish the yaw, roll, pitch and trim investigation between speeds of 85 to    65 mph, clean, then at 10 degree flaps, then at 20 degrees, and then at 30    degrees.  Some people even take the bottom end of the speed down to 60    mph and that would work well with the new tips and still keep you above the    predicted clean stall speed.  Of course if any of these step by step    objectives indicate any problems, stop at that point and make that first    landing at the previous  setting.  This is kind of what is    recommended in the FAA  Advisory Circular 90-89 (I hope I am remembering    that number right.)

   Buz



	


 

  

  [quote][b]

EAFerguson(at)aol.com
Guest

Posted: Tue Oct 21, 2008 4:58 am Post subject: Blanking Effect

In a message dated 10/20/2008 8:37:58 P.M. Eastern Daylight Time,  ryan(at)greenlandings.com writes:

  	  Quote: 	
		  Walt,



If I am not mistaken your aircraft is at Greg Hobbs    airport. 	


 

 Walt. Having visited Greg's place (~1000' runway with fences at both ends)  I would expect the first test flight to be made with at least 10 deg flaps. If  the runway is rough, as it was when I was there, any perceived loss on elevator  authority would call for an immediate abort. One suggestion would be to truck it  over to a local paved and longer runway like Marana. Not simple or cheap, but it  would provide a better setting for testing. 

  

 With 250+ hours and about that many take offs and landings in my Lightning,  I've never had any indication of blanking. I do most TOs no flap, but have been  through the full flap deployment range to test. I frequently side slip to  lose alt on landing, but don't think I've ever had full rudder in doing it.  Never a hint of loss of elevator authority.

  

 One possibility that has not been mentioned is to check the horizontal stab  incidence. If incorrect by even a small amount, this could be the problem.  

  

 Finally, the trim system makes a difference. You will have more elevator  authority with the servo trim than with the bungee. That comment will probably  start a new discussion thread, but trust me. We changed to the new system on  N17EF at 200+/- hours and there is a definite difference. "We" was mostly Nick,  I was there to watch. Since your's is a newly completed ship, it probably  has the new trim system, but I haven't seen that stated in the e-mails.

  

 Hope these comments help.

  

 Earl Ferguson



New MapQuest Local shows what's happening at your destination. Dining, Movies, Events, 200669822/aol?redir=http://local.mapquest.com/?ncid=emlcntnew00000002">Try it out! 

  [quote][b]

N1BZRich(at)AOL.COM
Guest

Posted: Tue Oct 21, 2008 5:05 am Post subject: Blanking Effect

In a message dated 10/21/2008 7:39:09 A.M. Eastern Daylight Time,  Kayberg(at)AOL.COM writes:

  	  Quote: 	
		  Sometimes there is a point in landing a Lightning where you have full    back stick, full flaps, nose up position and you simply must wait for the    touchdown.  The nose doesn't pitch down, which rules out the    "blanking".   But you can have a sense that you have no control for    a millisecond. 	


 

 Doug, 

     Right on.  Just substitute the word  Lightning for airplane and it sounds like the perfect set up for a full  stall landing.  The millisecond or whatever time delay will depend on just  how high you flared above the runway.  Hopefully six inches or so.   

 Buz



New MapQuest Local shows what's happening at your destination. Dining, Movies, Events, News & moreol?redir=http://local.mapquest.com/?ncid=emlcntnew00000002">Try it out! 

  [quote][b]

Kayberg(at)AOL.COM
Guest

Posted: Tue Oct 21, 2008 9:36 am Post subject: Blanking Effect

Few things in life compare to that feeling when you realize you are in full  stall about 10 feet above a runway....when you thought it was 10  inches!    Thankfully a Lightning will float in better than many  others if you just wait. 

  

 Of course power will help, but  that feeling is priceless!   

  

  

 Doug

  

  

  

 In a message dated 10/21/2008 9:06:05 A.M. Eastern Daylight Time,  N1BZRich(at)AOL.COM writes:

  	  Quote: 	
		        In a message dated 10/21/2008 7:39:09 A.M. Eastern Daylight Time,    Kayberg(at)AOL.COM writes:

    	  Quote: 	
		  Sometimes there is a point in landing a Lightning where you have full      back stick, full flaps, nose up position and you simply must wait for the      touchdown.  The nose doesn't pitch down, which rules out the      "blanking".   But you can have a sense that you have no control      for a millisecond. 	


   

   Doug, 

       Right on.  Just substitute the word    Lightning for airplane and it sounds like the perfect set up for a full    stall landing.  The millisecond or whatever time delay will depend on    just how high you flared above the runway.  Hopefully six inches or    so.  

   Buz



	


 

  

  [quote][b]

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