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patrickjladd(at)hotmail.c
Guest

Posted: Sat Mar 19, 2016 2:59 am Post subject: long legs

I may be sticking my neck out here and asking get slapped down but will  someone explain why having longer legs increases the STOL capability of our a/c.  Excepting of course the case where you deliberately hold the tail down on take  off.

 I agree with all the advantages which John listed, more wing area exposed  thus slowing landing run etc. However the first thing which  most of us do  on take off is to get the tail up into flying position thus reducing drag and  allowing increased acceleration. When the tail is up the the length of the u/c  is irrelevant. In fact having the extra wing area exposed by having long legs  slows the planes acceleration for exactly the same reason that it shortens the  landing run.

 When the plane is up on two wheels the AOA is that which was designed  in.

 Comments about commercial a/c are largely irrelevant as they are (mainly)  tricycle gear and the wing is in flying position (more or less) the whole  time.

 There may be good reasons for making u/c legs longer but I am not convinced  that STOL  is one of them except the `keep the skid on the ground until she  drags herself off` scenario which I mentioned..

 Enlightenment please.

 Pat

Richard Pike

Joined: 09 Jan 2006
Posts: 1670
Location: Blountville, Tennessee

Posted: Sat Mar 19, 2016 3:24 am Post subject: Re: long legs

Make the gear legs long enough and your fat friends will not be able to get in. Which enables the airplane to get off the ground quicker.



Glad to help out.

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

ceengland7(at)gmail.com
Guest

Posted: Sat Mar 19, 2016 5:34 am Post subject: long legs

On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

 	  Quote: 	
		      I may be sticking my neck out here and asking get slapped down but will  someone explain why having longer legs increases the STOL capability of our a/c.  Excepting of course the case where you deliberately hold the tail down on take  off.

 I agree with all the advantages which John listed, more wing area exposed  thus slowing landing run etc. However the first thing which  most of us do  on take off is to get the tail up into flying position thus reducing drag and  allowing increased acceleration. When the tail is up the the length of the u/c  is irrelevant. In fact having the extra wing area exposed by having long legs  slows the planes acceleration for exactly the same reason that it shortens the  landing run.

 When the plane is up on two wheels the AOA is that which was designed  in.

 Comments about commercial a/c are largely irrelevant as they are (mainly)  tricycle gear and the wing is in flying position (more or less) the whole  time.

 There may be good reasons for making u/c legs longer but I am not convinced  that STOL  is one of them except the `keep the skid on the ground until she  drags herself off` scenario which I mentioned..

 Enlightenment please.

 Pat

 

	


I'll take a crack at it, in general terms. You can decide if it applies to Kolbs.

If you watch videos of hard core bush flying, the pilot will hold the brakes and raise the tail prior to starting the takeoff roll (to minimize wing drag, as you point out). When he's got max available power, he releases the brakes. As soon as he's got minimum flying speed, he rotates & the plane jumps into the air. Now, most taildraggers sit on the ground with the wing at a significantly lower angle than critical (stall) AOA. So in stock condition, they can't be rotated to lift off at anywhere near stall speed. So, their minimum speed for takeoff is limited (made higher) by the length of the main gear legs. If the same trick is tried with 'short legs', the pilot would slam the tailwheel into the ground when he rotates. FWIW, there are videos of airliners actually dragging the rear of the fuselage on the ground when they over-rotate. Airliners (at least some of them) actually give up significant landing speed reduction because they don't want the weight of long gear legs when they always have plenty of runway for 'driving it on' in landing.

In landing mode, it's just as important. In normal flying, a pilot would try to '3 point', having the mains & tailwheel touch at the same time to land at minimum airspeed. But, since the wing isn't at critical AOA in 3 point attitude, he's not really landing at minimum airspeed. If the mains were longer, he could land slower. In bush flying, it gets worse. Again, watching extreme bush flying, you'll see the pilot wheel land and keep the tail off the ground until he's almost stopped. With a typical taildragger, he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but he does it to protect the tailwheel from damage, from rough ground and from impact damage of dropping it in. If the legs are extended enough, he can have full stall AOA available from the wing, without the tailwheel being on the ground. Obviously, this will let him land slower & shorter.

Does any of that apply to Kolbs?

rowedenny

Joined: 09 Mar 2008
Posts: 338
Location: Western PA

Posted: Sat Mar 19, 2016 5:46 am Post subject: long legs

Bingo on all points.

Do not archive 



Dennis "Skid" Rowe



On Mar 19, 2016, at 9:34 AM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:

 	  Quote: 	
		  



On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

 	  Quote: 	
		      I may be sticking my neck out here and asking get slapped down but will  someone explain why having longer legs increases the STOL capability of our a/c.  Excepting of course the case where you deliberately hold the tail down on take  off.

 I agree with all the advantages which John listed, more wing area exposed  thus slowing landing run etc. However the first thing which  most of us do  on take off is to get the tail up into flying position thus reducing drag and  allowing increased acceleration. When the tail is up the the length of the u/c  is irrelevant. In fact having the extra wing area exposed by having long legs  slows the planes acceleration for exactly the same reason that it shortens the  landing run.

 When the plane is up on two wheels the AOA is that which was designed  in.

 Comments about commercial a/c are largely irrelevant as they are (mainly)  tricycle gear and the wing is in flying position (more or less) the whole  time.

 There may be good reasons for making u/c legs longer but I am not convinced  that STOL  is one of them except the `keep the skid on the ground until she  drags herself off` scenario which I mentioned..

 Enlightenment please.

 Pat

 

	


I'll take a crack at it, in general terms. You can decide if it applies to Kolbs.

If you watch videos of hard core bush flying, the pilot will hold the brakes and raise the tail prior to starting the takeoff roll (to minimize wing drag, as you point out). When he's got max available power, he releases the brakes. As soon as he's got minimum flying speed, he rotates & the plane jumps into the air. Now, most taildraggers sit on the ground with the wing at a significantly lower angle than critical (stall) AOA. So in stock condition, they can't be rotated to lift off at anywhere near stall speed. So, their minimum speed for takeoff is limited (made higher) by the length of the main gear legs. If the same trick is tried with 'short legs', the pilot would slam the tailwheel into the ground when he rotates. FWIW, there are videos of airliners actually dragging the rear of the fuselage on the ground when they over-rotate. Airliners (at least some of them) actually give up significant landing speed reduction because they don't want the weight of long gear legs when they always have plenty of runway for 'driving it on' in landing.

In landing mode, it's just as important. In normal flying, a pilot would try to '3 point', having the mains & tailwheel touch at the same time to land at minimum airspeed. But, since the wing isn't at critical AOA in 3 point attitude, he's not really landing at minimum airspeed. If the mains were longer, he could land slower. In bush flying, it gets worse. Again, watching extreme bush flying, you'll see the pilot wheel land and keep the tail off the ground until he's almost stopped. With a typical taildragger, he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but he does it to protect the tailwheel from damage, from rough ground and from impact damage of dropping it in. If the legs are extended enough, he can have full stall AOA available from the wing, without the tailwheel being on the ground. Obviously, this will let him land slower & shorter.

Does any of that apply to Kolbs?

patrickjladd(at)hotmail.c
Guest

Posted: Sat Mar 19, 2016 6:40 am Post subject: long legs

Thanks Charlie,

 i can see the reasoning and in fact I saw a guy up in Fairbanks in a Super  Cub pulling the `tail up, full throttle trick`. He powered up, standing on the  brakes, hauled it off the ground by pushing the tail down and climbing out at  just above stall speed.. He did a circuit and landed again, tail down and  hanging on his prop at full chat,  like a helicopter. All in an incredibly  short time. I filmed it with a video camera in one take.

 I somehow doubt that many Kolbers have the brakes, to be able to come close  to emulating that performance. Without some actual measurements it is impossible  to calculate accurately the increased AOA available and I was never any good at  trig anyway but assuming 10ft between mains and tail wheel and an increase in  height of the gear legs of say 4 inches, by how many degrees does that increase  the AOA? 1 degree? 1.5 degrees.? No doubt someone on the list will work it  out.

 It may well be worth extending legs for other reasons but STOL?.  Questionable.

  

 Pat

    

  From: Charlie England (ceengland7(at)gmail.com) 

 Sent: Saturday, March 19, 2016 1:34 PM

 To: kolb-list(at)matronics.com (kolb-list(at)matronics.com) 

 Subject: Re: long legs

  



    

   

 On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

  	  Quote: 	
		              I may be sticking my neck out here and asking get slapped down but will    someone explain why having longer legs increases the STOL capability of our    a/c. Excepting of course the case where you deliberately hold the tail down on    take off.

   I agree with all the advantages which John listed, more wing area exposed    thus slowing landing run etc. However the first thing which  most of us    do on take off is to get the tail up into flying position thus reducing drag    and allowing increased acceleration. When the tail is up the the length of the    u/c is irrelevant. In fact having the extra wing area exposed by having long    legs slows the planes acceleration for exactly the same reason that it    shortens the landing run.

   When the plane is up on two wheels the AOA is that which was designed    in.

   Comments about commercial a/c are largely irrelevant as they are (mainly)    tricycle gear and the wing is in flying position (more or less) the whole    time.

   There may be good reasons for making u/c legs longer but I am not    convinced that STOL  is one of them except the `keep the skid on the    ground until she drags herself off` scenario which I mentioned..

   Enlightenment please.

   Pat



	


  



 I'll take a crack at it, in general terms. You can decide  if it applies to Kolbs.

  

 If you watch videos of hard core bush flying, the pilot  will hold the brakes and raise the tail prior to starting the takeoff roll (to  minimize wing drag, as you point out). When he's got max available power, he  releases the brakes. As soon as he's got minimum flying speed, he rotates &  the plane jumps into the air. Now, most taildraggers sit on the ground with the  wing at a significantly lower angle than critical (stall) AOA. So in stock  condition, they can't be rotated to lift off at anywhere near stall speed. So,  their minimum speed for takeoff is limited (made higher) by the length of the  main gear legs. If the same trick is tried with 'short legs', the pilot would  slam the tailwheel into the ground when he rotates. FWIW, there are videos of  airliners actually dragging the rear of the fuselage on the ground when they  over-rotate. Airliners (at least some of them) actually give up significant  landing speed reduction because they don't want the weight of long gear legs  when they always have plenty of runway for 'driving it on' in landing.

  

 In landing mode, it's just as important. In normal  flying, a pilot would try to '3 point', having the mains & tailwheel touch  at the same time to land at minimum airspeed. But, since the wing isn't at  critical AOA in 3 point attitude, he's not really landing at minimum airspeed.  If the mains were longer, he could land slower. In bush flying, it gets worse.  Again, watching extreme bush flying, you'll see the pilot wheel land and keep  the tail off the ground until he's almost stopped. With a typical taildragger,  he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but he  does it to protect the tailwheel from damage, from rough ground and from impact  damage of dropping it in. If the legs are extended enough, he can have full  stall AOA available from the wing, without the tailwheel being on the ground.  Obviously, this will let him land slower & shorter.

  

 Does any of that apply to  Kolbs?

ceengland7(at)gmail.com
Guest

Posted: Sat Mar 19, 2016 7:28 am Post subject: long legs

Since typical AOA is around 14-15 degrees at stall, a 1.5 degree increase could be close to a 10% increase in 3 point attitude. Not something to sneeze at.



Again, you must decide if it applies to Kolbs, and whether it actually matters to you for your style of flying. Who would think that a stock Super Cub needed shorter field performance, but a lot of bush fliers obviously consider it inadequate for their purposes.

On Sat, Mar 19, 2016 at 9:40 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

 	  Quote: 	
		      Thanks Charlie,

 i can see the reasoning and in fact I saw a guy up in Fairbanks in a Super  Cub pulling the `tail up, full throttle trick`. He powered up, standing on the  brakes, hauled it off the ground by pushing the tail down and climbing out at  just above stall speed.. He did a circuit and landed again, tail down and  hanging on his prop at full chat,  like a helicopter. All in an incredibly  short time. I filmed it with a video camera in one take.

 I somehow doubt that many Kolbers have the brakes, to be able to come close  to emulating that performance. Without some actual measurements it is impossible  to calculate accurately the increased AOA available and I was never any good at  trig anyway but assuming 10ft between mains and tail wheel and an increase in  height of the gear legs of say 4 inches, by how many degrees does that increase  the AOA? 1 degree? 1.5 degrees.? No doubt someone on the list will work it  out.

 It may well be worth extending legs for other reasons but STOL?.  Questionable.

  

 Pat

    

  From: Charlie England (ceengland7(at)gmail.com) 

 Sent: Saturday, March 19, 2016 1:34 PM

 To: kolb-list(at)matronics.com (kolb-list(at)matronics.com) 

 Subject: Re: long legs

  



    

   

 On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

  	  Quote: 	
		              I may be sticking my neck out here and asking get slapped down but will    someone explain why having longer legs increases the STOL capability of our    a/c. Excepting of course the case where you deliberately hold the tail down on    take off.

   I agree with all the advantages which John listed, more wing area exposed    thus slowing landing run etc. However the first thing which  most of us    do on take off is to get the tail up into flying position thus reducing drag    and allowing increased acceleration. When the tail is up the the length of the    u/c is irrelevant. In fact having the extra wing area exposed by having long    legs slows the planes acceleration for exactly the same reason that it    shortens the landing run.

   When the plane is up on two wheels the AOA is that which was designed    in.

   Comments about commercial a/c are largely irrelevant as they are (mainly)    tricycle gear and the wing is in flying position (more or less) the whole    time.

   There may be good reasons for making u/c legs longer but I am not    convinced that STOL  is one of them except the `keep the skid on the    ground until she drags herself off` scenario which I mentioned..

   Enlightenment please.

   Pat



	


  



 I'll take a crack at it, in general terms. You can decide  if it applies to Kolbs.

  

 If you watch videos of hard core bush flying, the pilot  will hold the brakes and raise the tail prior to starting the takeoff roll (to  minimize wing drag, as you point out). When he's got max available power, he  releases the brakes. As soon as he's got minimum flying speed, he rotates &  the plane jumps into the air. Now, most taildraggers sit on the ground with the  wing at a significantly lower angle than critical (stall) AOA. So in stock  condition, they can't be rotated to lift off at anywhere near stall speed. So,  their minimum speed for takeoff is limited (made higher) by the length of the  main gear legs. If the same trick is tried with 'short legs', the pilot would  slam the tailwheel into the ground when he rotates. FWIW, there are videos of  airliners actually dragging the rear of the fuselage on the ground when they  over-rotate. Airliners (at least some of them) actually give up significant  landing speed reduction because they don't want the weight of long gear legs  when they always have plenty of runway for 'driving it on' in landing.

  

 In landing mode, it's just as important. In normal  flying, a pilot would try to '3 point', having the mains & tailwheel touch  at the same time to land at minimum airspeed. But, since the wing isn't at  critical AOA in 3 point attitude, he's not really landing at minimum airspeed.  If the mains were longer, he could land slower. In bush flying, it gets worse.  Again, watching extreme bush flying, you'll see the pilot wheel land and keep  the tail off the ground until he's almost stopped. With a typical taildragger,  he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but he  does it to protect the tailwheel from damage, from rough ground and from impact  damage of dropping it in. If the legs are extended enough, he can have full  stall AOA available from the wing, without the tailwheel being on the ground.  Obviously, this will let him land slower & shorter.

  

 Does any of that apply to  Kolbs?

patrickjladd(at)hotmail.c
Guest

Posted: Sat Mar 19, 2016 9:18 am Post subject: long legs

Good point Richard.

In general my fat friends did not get a look in. Fat girls now.....Pat



--

tc1917(at)bellsouth.net
Guest

Posted: Sun Mar 20, 2016 1:57 am Post subject: Long legs

The slingshot has long legs to facilitate 9 degrees AOA.  Most have 12 degrees AOA.  That gives the SS remarkable speed capabilities without the boom raising up. I can cruise at 90/100 without problems. As Hauck mentioned, the boom does drop but not until around 60. Still not a problem.  I believe if you put longer gear on a standard firestar you would have difficult ground handling and you might have lift off before rotation.   The SS has to rotate quickly and then has to drop its tail to get proper AOA which brings the tail down considerably.  Landing slow the tail is in a three point configuration to get back to 12 degrees AOA. You can land the SS high on the mains but landing roll is faster.  Not sure if the firefly has the same or not. I am sure of one thing, the SS is the fastest, most sensitive aircraft of the bunch.  With a rotax 912 80 hp on her back, it is a rocket.   Abt two hundred ft on the ground, less than three to land and cuts through the bumps and zips around like it it is on a tether.  Not for the average bear but a ball when you master it.  Best of the kolbs i think. It would be nice the have the baggage capabilities as Hauck does!  Ted Cowan slingshot 912 zoom zoom



Sent from my iPhone

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Mon Mar 21, 2016 8:29 am Post subject: long legs

Patrick, My Mk III has aluminum legs, my friend's Mk IIIX has steel legs and lower wing incidence. Neither can get a full stall landing. If I do I land tail wheel first. Perhaps a full stall landing could be achieved with longer legs and higher incidence. When I get my Mk III rebuilt perhaps I'll know.



Rick Girard

On Sat, Mar 19, 2016 at 10:26 AM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:

 	  Quote: 	
		  Since typical AOA is around 14-15 degrees at stall, a 1.5 degree increase could be close to a 10% increase in 3 point attitude. Not something to sneeze at.



Again, you must decide if it applies to Kolbs, and whether it actually matters to you for your style of flying. Who would think that a stock Super Cub needed shorter field performance, but a lot of bush fliers obviously consider it inadequate for their purposes.

On Sat, Mar 19, 2016 at 9:40 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

 	  Quote: 	
		      Thanks Charlie,

 i can see the reasoning and in fact I saw a guy up in Fairbanks in a Super  Cub pulling the `tail up, full throttle trick`. He powered up, standing on the  brakes, hauled it off the ground by pushing the tail down and climbing out at  just above stall speed.. He did a circuit and landed again, tail down and  hanging on his prop at full chat,  like a helicopter. All in an incredibly  short time. I filmed it with a video camera in one take.

 I somehow doubt that many Kolbers have the brakes, to be able to come close  to emulating that performance. Without some actual measurements it is impossible  to calculate accurately the increased AOA available and I was never any good at  trig anyway but assuming 10ft between mains and tail wheel and an increase in  height of the gear legs of say 4 inches, by how many degrees does that increase  the AOA? 1 degree? 1.5 degrees.? No doubt someone on the list will work it  out.

 It may well be worth extending legs for other reasons but STOL?.  Questionable.

  

 Pat

    

  From: Charlie England (ceengland7(at)gmail.com) 

 Sent: Saturday, March 19, 2016 1:34 PM

 To: kolb-list(at)matronics.com (kolb-list(at)matronics.com) 

 Subject: Re: long legs

  



    

   

 On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

  	  Quote: 	
		              I may be sticking my neck out here and asking get slapped down but will    someone explain why having longer legs increases the STOL capability of our    a/c. Excepting of course the case where you deliberately hold the tail down on    take off.

   I agree with all the advantages which John listed, more wing area exposed    thus slowing landing run etc. However the first thing which  most of us    do on take off is to get the tail up into flying position thus reducing drag    and allowing increased acceleration. When the tail is up the the length of the    u/c is irrelevant. In fact having the extra wing area exposed by having long    legs slows the planes acceleration for exactly the same reason that it    shortens the landing run.

   When the plane is up on two wheels the AOA is that which was designed    in.

   Comments about commercial a/c are largely irrelevant as they are (mainly)    tricycle gear and the wing is in flying position (more or less) the whole    time.

   There may be good reasons for making u/c legs longer but I am not    convinced that STOL  is one of them except the `keep the skid on the    ground until she drags herself off` scenario which I mentioned..

   Enlightenment please.

   Pat



	


  



 I'll take a crack at it, in general terms. You can decide  if it applies to Kolbs.

  

 If you watch videos of hard core bush flying, the pilot  will hold the brakes and raise the tail prior to starting the takeoff roll (to  minimize wing drag, as you point out). When he's got max available power, he  releases the brakes. As soon as he's got minimum flying speed, he rotates &  the plane jumps into the air. Now, most taildraggers sit on the ground with the  wing at a significantly lower angle than critical (stall) AOA. So in stock  condition, they can't be rotated to lift off at anywhere near stall speed. So,  their minimum speed for takeoff is limited (made higher) by the length of the  main gear legs. If the same trick is tried with 'short legs', the pilot would  slam the tailwheel into the ground when he rotates. FWIW, there are videos of  airliners actually dragging the rear of the fuselage on the ground when they  over-rotate. Airliners (at least some of them) actually give up significant  landing speed reduction because they don't want the weight of long gear legs  when they always have plenty of runway for 'driving it on' in landing.

  

 In landing mode, it's just as important. In normal  flying, a pilot would try to '3 point', having the mains & tailwheel touch  at the same time to land at minimum airspeed. But, since the wing isn't at  critical AOA in 3 point attitude, he's not really landing at minimum airspeed.  If the mains were longer, he could land slower. In bush flying, it gets worse.  Again, watching extreme bush flying, you'll see the pilot wheel land and keep  the tail off the ground until he's almost stopped. With a typical taildragger,  he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but he  does it to protect the tailwheel from damage, from rough ground and from impact  damage of dropping it in. If the legs are extended enough, he can have full  stall AOA available from the wing, without the tailwheel being on the ground.  Obviously, this will let him land slower & shorter.

  

 Does any of that apply to  Kolbs?





 

	


 



	




-- 

“Blessed are the cracked, for they shall let in the light.”   Groucho Marx

_________________
The smallest miracle right in front of you is enough to make you happy....

patrickjladd(at)hotmail.c
Guest

Posted: Mon Mar 21, 2016 8:57 am Post subject: long legs

I look forward to a definitive statement.

 The guy in the Super Cub, at full throttle, lowered his plane onto the tail  wheel at almost nil forward speed, cut back on the throttle  and then the  mains crashed down onto its balloon bush tyres.Hard on the system.   Breaking my heart not to have a plane to fly any more. We have had a week in the  middle of a large High pressure system. Glorious flying weather and me stuck  here playing with a 18” diameter quadrocopter my wife bought me fro  Christmas.Oh! Bugger. Pat

    

  From: Richard Girard (aslsa.rng(at)gmail.com) 

 Sent: Monday, March 21, 2016 4:29 PM

 To: kolb-list(at)matronics.com (kolb-list(at)matronics.com) 

 Subject: Re: long legs

  



  Patrick, My Mk III has aluminum legs, my friend's Mk IIIX has steel  legs and lower wing incidence. Neither can get a full stall landing. If I do I  land tail wheel first. Perhaps a full stall landing could be achieved with  longer legs and higher incidence. When I get my Mk III rebuilt perhaps I'll  know.   

 Rick Girard



   

 On Sat, Mar 19, 2016 at 10:26 AM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:

  	  Quote: 	
		     Since typical AOA is around 14-15 degrees at stall, a 1.5 degree    increase could be close to a 10% increase in 3 point attitude. Not something    to sneeze at.     

   Again, you must decide if it applies to Kolbs, and whether it actually    matters to you for your style of flying. Who would think that a stock Super    Cub needed shorter field performance, but a lot of bush fliers obviously    consider it inadequate for their purposes.



             

   On Sat, Mar 19, 2016 at 9:40 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

    	  Quote: 	
		                      Thanks Charlie,

     i can see the reasoning and in fact I saw a guy up in Fairbanks in a      Super Cub pulling the `tail up, full throttle trick`. He powered up,      standing on the brakes, hauled it off the ground by pushing the tail down      and climbing out at just above stall speed.. He did a circuit and landed      again, tail down and hanging on his prop at full chat,  like a      helicopter. All in an incredibly short time. I filmed it with a video camera      in one take.

     I somehow doubt that many Kolbers have the brakes, to be able to come      close to emulating that performance. Without some actual measurements it is      impossible to calculate accurately the increased AOA available and I was      never any good at trig anyway but assuming 10ft between mains and tail wheel      and an increase in height of the gear legs of say 4 inches, by how many      degrees does that increase the AOA? 1 degree? 1.5 degrees.? No doubt someone      on the list will work it out.

     It may well be worth extending legs for other reasons but STOL?.      Questionable.

      

     Pat

                

          From: Charlie England (ceengland7(at)gmail.com) 

     Sent: Saturday, March 19, 2016 1:34 PM

     To: kolb-list(at)matronics.com (kolb-list(at)matronics.com) 

     Subject: Re: long legs

      



                

           

     On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

      	  Quote: 	
		                              I may be sticking my neck out here and asking get slapped down but        will someone explain why having longer legs increases the STOL capability        of our a/c. Excepting of course the case where you deliberately hold the        tail down on take off.

       I agree with all the advantages which John listed, more wing area        exposed thus slowing landing run etc. However the first thing which         most of us do on take off is to get the tail up into flying position thus        reducing drag and allowing increased acceleration. When the tail is up the        the length of the u/c is irrelevant. In fact having the extra wing area        exposed by having long legs slows the planes acceleration for exactly the        same reason that it shortens the landing run.

       When the plane is up on two wheels the AOA is that which was designed        in.

       Comments about commercial a/c are largely irrelevant as they are        (mainly) tricycle gear and the wing is in flying position (more or less)        the whole time.

       There may be good reasons for making u/c legs longer but I am not        convinced that STOL  is one of them except the `keep the skid on the        ground until she drags herself off` scenario which I mentioned..

       Enlightenment please.

       Pat



	


      



     I'll take a crack at it, in general terms. You can      decide if it applies to Kolbs.

      

     If you watch videos of hard core bush flying, the      pilot will hold the brakes and raise the tail prior to starting the takeoff      roll (to minimize wing drag, as you point out). When he's got max available      power, he releases the brakes. As soon as he's got minimum flying speed, he      rotates & the plane jumps into the air. Now, most taildraggers sit on      the ground with the wing at a significantly lower angle than critical      (stall) AOA. So in stock condition, they can't be rotated to lift off at      anywhere near stall speed. So, their minimum speed for takeoff is limited      (made higher) by the length of the main gear legs. If the same trick is      tried with 'short legs', the pilot would slam the tailwheel into the ground      when he rotates. FWIW, there are videos of airliners actually dragging the      rear of the fuselage on the ground when they over-rotate. Airliners (at      least some of them) actually give up significant landing speed reduction      because they don't want the weight of long gear legs when they always have      plenty of runway for 'driving it on' in landing.

      

     In landing mode, it's just as important. In normal      flying, a pilot would try to '3 point', having the mains & tailwheel      touch at the same time to land at minimum airspeed. But, since the wing      isn't at critical AOA in 3 point attitude, he's not really landing at      minimum airspeed. If the mains were longer, he could land slower. In bush      flying, it gets worse. Again, watching extreme bush flying, you'll see the      pilot wheel land and keep the tail off the ground until he's almost stopped.      With a typical taildragger, he's carrying quite a bit of extra airspeed to      'wheel land' the plane, but he does it to protect the tailwheel from damage,      from rough ground and from impact damage of dropping it in. If the legs are      extended enough, he can have full stall AOA available from the wing, without      the tailwheel being on the ground. Obviously, this will let him land slower      & shorter.

      

     Does any of that apply to      Kolbs?



	


    



	




  

-- 

      “Blessed  are the cracked, for they shall let in the light.”   Groucho Marx

victorbravo(at)sbcglobal.
Guest

Posted: Mon Mar 21, 2016 9:22 am Post subject: long legs

 	  Quote: 	
		  From my research, and hearing from other people who have been around Kolbs for many many years, I think it is safe to say that Homer Kolb designed this series of aircraft for good handling, good manners, and able to be flown easily by a low time pilot. By all accounts he succeeded and created a fantastic little airplane. 


	


But physics do not lie... in order to be a great airplane in one area, design sacrifices must be made in some other area. This is why a LearJet is not appropriate for a low time pilot, and this is why a Cessna 172 is (usually) not very exciting for a high time pilot. I have no doubt that Mr. Kolb understood this, and chose safety/easy handling over maximum possible performance. The sales and success of the Kolb fleet has proven him right. 



The Kolbs are world renowned for being docile and not demanding. The price paid for that is that some performance has been sacrificed.



Raising the ground angle high enough so that the airplane can perform a full-stall 3 point landing will clearly allow the airplane to realize the maximum STOL performance that the wing and engine combination is capable of delivering. That is basic textbook aeroduynamics. But since the Kolb apparently has good STOL performance with the stock configuration, it's been a non-issue for the majority of Kolb pilots.



Speaking ONLY for myself, I would like to maximize the STOL performance of my aircraft, because I am heavier than an average pilot, and my airplane will not meet the 254 UL weight either. So rather than having to put a $20K, 100HP engine on it, I believe I will get 2/3 of the same benefit by having a tall enough landing gear for the wing to fly sooner. The price I have to pay for that is that I cannot be a low-time, beginner pilot, and the airplane will be a little slower (higher drag and drag further underneath the CG).



The modifications that I am planning for my aircraft will not be for everyone. But I'm hopeful that they will suit my needs.



Bill Berle

www.ezflaphandle.com  - safety & performance upgrade for light aircraft

www.grantstar.net           - winning proposals for non-profit and for-profit entities



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

On Mon, 3/21/16, Richard Girard <aslsa.rng(at)gmail.com> wrote:



 Subject: Re: long legs

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

 Date: Monday, March 21, 2016, 9:29 AM

 

 Patrick,

 My Mk III has aluminum legs, my friend's Mk IIIX has

 steel legs and lower wing incidence. Neither can get a full

 stall landing. If I do I land tail wheel first. Perhaps a

 full stall landing could be achieved with longer legs and

 higher incidence. When I get my Mk III rebuilt perhaps

 I'll know.

 Rick

 Girard

 On Sat, Mar 19, 2016 at

 10:26 AM, Charlie England <ceengland7(at)gmail.com>

 wrote:

 Since typical AOA is around 14-15 degrees at

 stall, a 1.5 degree increase could be close to a 10%

 increase in 3 point attitude. Not something to sneeze

 at.

 Again, you must decide

 if it applies to Kolbs, and whether it actually matters to

 you for your style of flying. Who would think that a stock

 Super Cub needed shorter field performance, but a lot of

 bush fliers obviously consider it inadequate for their

 purposes.

 On Sat, Mar 19, 2016 at

 9:40 AM, Patrick Ladd <patrickjladd(at)hotmail.com>

 wrote:

 

 

 

 

 Thanks Charlie,

 i can see the reasoning and in fact I saw a guy up in

 Fairbanks in a Super 

 Cub pulling the `tail up, full throttle trick`. He powered

 up, standing on the 

 brakes, hauled it off the ground by pushing the tail down

 and climbing out at 

 just above stall speed.. He did a circuit and landed again,

 tail down and 

 hanging on his prop at full chat,  like a helicopter. All

 in an incredibly 

 short time. I filmed it with a video camera in one

 take.

 I somehow doubt that many Kolbers have the brakes, to

 be able to come close 

 to emulating that performance. Without some actual

 measurements it is impossible 

 to calculate accurately the increased AOA available and I

 was never any good at 

 trig anyway but assuming 10ft between mains and tail wheel

 and an increase in 

 height of the gear legs of say 4 inches, by how many degrees

 does that increase 

 the AOA? 1 degree? 1.5 degrees.? No doubt someone on the

 list will work it 

 out.

 It may well be worth extending legs for other reasons

 but STOL?. 

 Questionable.

  

 Pat

 

 

  

 

 From: Charlie

 England 

 Sent: Saturday, March 19, 2016 1:34 PM

 To: kolb-list(at)matronics.com

 

 Subject: Re: long

 legs

  

 

 

  

 

  

 On Sat, Mar 19, 2016

 at 5:58 AM, Patrick Ladd <patrickjladd(at)hotmail.com>

 wrote:

 

 

   

   

   

   I may be sticking my neck out here and asking get

 slapped down but will 

   someone explain why having longer legs increases the STOL

 capability of our 

   a/c. Excepting of course the case where you deliberately

 hold the tail down on 

   take off.

   I agree with all the advantages which John listed,

 more wing area exposed 

   thus slowing landing run etc. However the first thing

 which  most of us 

   do on take off is to get the tail up into flying position

 thus reducing drag 

   and allowing increased acceleration. When the tail is up

 the the length of the 

   u/c is irrelevant. In fact having the extra wing area

 exposed by having long 

   legs slows the planes acceleration for exactly the same

 reason that it 

   shortens the landing run.

   When the plane is up on two wheels the AOA is that

 which was designed 

   in.

   Comments about commercial a/c are largely irrelevant

 as they are (mainly) 

   tricycle gear and the wing is in flying position (more or

 less) the whole 

   time.

   There may be good reasons for making u/c legs longer

 but I am not 

   convinced that STOL  is one of them except the `keep the

 skid on the 

   ground until she drags herself off` scenario which I

 mentioned..

   Enlightenment please.

   Pat

  

 I'll take a crack

 at it, in general terms. You can decide 

 if it applies to Kolbs.

  

 If you watch videos of

 hard core bush flying, the pilot 

 will hold the brakes and raise the tail prior to starting

 the takeoff roll (to 

 minimize wing drag, as you point out). When he's got max

 available power, he 

 releases the brakes. As soon as he's got minimum flying

 speed, he rotates & 

 the plane jumps into the air. Now, most taildraggers sit on

 the ground with the 

 wing at a significantly lower angle than critical (stall)

 AOA. So in stock 

 condition, they can't be rotated to lift off at anywhere

 near stall speed. So, 

 their minimum speed for takeoff is limited (made higher) by

 the length of the 

 main gear legs. If the same trick is tried with 'short

 legs', the pilot would 

 slam the tailwheel into the ground when he rotates. FWIW,

 there are videos of 

 airliners actually dragging the rear of the fuselage on the

 ground when they 

 over-rotate. Airliners (at least some of them) actually give

 up significant 

 landing speed reduction because they don't want the

 weight of long gear legs 

 when they always have plenty of runway for 'driving it

 on' in landing.

  

 In landing mode,

 it's just as important. In normal 

 flying, a pilot would try to '3 point', having the

 mains & tailwheel touch 

 at the same time to land at minimum airspeed. But, since the

 wing isn't at 

 critical AOA in 3 point attitude, he's not really

 landing at minimum airspeed. 

 If the mains were longer, he could land slower. In bush

 flying, it gets worse. 

 Again, watching extreme bush flying, you'll see the

 pilot wheel land and keep 

 the tail off the ground until he's almost stopped. With

 a typical taildragger, 

 he's carrying quite a bit of extra airspeed to

 'wheel land' the plane, but he 

 does it to protect the tailwheel from damage, from rough

 ground and from impact 

 damage of dropping it in. If the legs are extended enough,

 he can have full 

 stall AOA available from the wing, without the tailwheel

 being on the ground. 

 Obviously, this will let him land slower &

 shorter.

  

 Does any of that apply

 to 

 Kolbs?

 

 

 

 

 

 -- 

 “Blessed are

 the cracked, for they shall let in the light.”   Groucho

 Marx

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Mon Mar 21, 2016 3:54 pm Post subject: long legs

Rick/Kolbers:

 

I've been experimenting and flying with heat treated 4130 tubular gear legs on Kolbs since 1987.  Had 36" legs on the original FS.  Completely different main gear on my MKIII, with axles 8" forward and nice nose high attitude.  Yes, they did and do fine full stall landings, get off the ground quick, and have no nose over problems, even at full throttle and brakes.

 

john h

mkIII

Fort Campbell, Kentucky

 

 

 

 

From: owner-kolb-list-server(at)matronics.com [mailto:owner-kolb-list-server(at)matronics.com] On Behalf Of Richard Girard

Sent: Monday, March 21, 2016 11:29 AM

To: kolb-list(at)matronics.com

Subject: Re: long legs



 

Patrick, My Mk III has aluminum legs, my friend's Mk IIIX has steel legs and lower wing incidence. Neither can get a full stall landing. If I do I land tail wheel first. Perhaps a full stall landing could be achieved with longer legs and higher incidence. When I get my Mk III rebuilt perhaps I'll know.

 



Rick Girard

 

On Sat, Mar 19, 2016 at 10:26 AM, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:

Since typical AOA is around 14-15 degrees at stall, a 1.5 degree increase could be close to a 10% increase in 3 point attitude. Not something to sneeze at.

 



Again, you must decide if it applies to Kolbs, and whether it actually matters to you for your style of flying. Who would think that a stock Super Cub needed shorter field performance, but a lot of bush fliers obviously consider it inadequate for their purposes.

 

On Sat, Mar 19, 2016 at 9:40 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

Thanks Charlie,



i can see the reasoning and in fact I saw a guy up in Fairbanks in a Super Cub pulling the `tail up, full throttle trick`. He powered up, standing on the brakes, hauled it off the ground by pushing the tail down and climbing out at just above stall speed.. He did a circuit and landed again, tail down and hanging on his prop at full chat,  like a helicopter. All in an incredibly short time. I filmed it with a video camera in one take.



I somehow doubt that many Kolbers have the brakes, to be able to come close to emulating that performance. Without some actual measurements it is impossible to calculate accurately the increased AOA available and I was never any good at trig anyway but assuming 10ft between mains and tail wheel and an increase in height of the gear legs of say 4 inches, by how many degrees does that increase the AOA? 1 degree? 1.5 degrees.? No doubt someone on the list will work it out.



It may well be worth extending legs for other reasons but STOL?. Questionable.



 



Pat



 



From: Charlie England (ceengland7(at)gmail.com) 



Sent: Saturday, March 19, 2016 1:34 PM



To: kolb-list(at)matronics.com (kolb-list(at)matronics.com) 



Subject: Re: long legs



 

 



 



On Sat, Mar 19, 2016 at 5:58 AM, Patrick Ladd <patrickjladd(at)hotmail.com (patrickjladd(at)hotmail.com)> wrote:

I may be sticking my neck out here and asking get slapped down but will someone explain why having longer legs increases the STOL capability of our a/c. Excepting of course the case where you deliberately hold the tail down on take off.



I agree with all the advantages which John listed, more wing area exposed thus slowing landing run etc. However the first thing which  most of us do on take off is to get the tail up into flying position thus reducing drag and allowing increased acceleration. When the tail is up the the length of the u/c is irrelevant. In fact having the extra wing area exposed by having long legs slows the planes acceleration for exactly the same reason that it shortens the landing run.



When the plane is up on two wheels the AOA is that which was designed in.



Comments about commercial a/c are largely irrelevant as they are (mainly) tricycle gear and the wing is in flying position (more or less) the whole time.



There may be good reasons for making u/c legs longer but I am not convinced that STOL  is one of them except the `keep the skid on the ground until she drags herself off` scenario which I mentioned..



Enlightenment please.



Pat



 

I'll take a crack at it, in general terms. You can decide if it applies to Kolbs.



 



If you watch videos of hard core bush flying, the pilot will hold the brakes and raise the tail prior to starting the takeoff roll (to minimize wing drag, as you point out). When he's got max available power, he releases the brakes. As soon as he's got minimum flying speed, he rotates & the plane jumps into the air. Now, most taildraggers sit on the ground with the wing at a significantly lower angle than critical (stall) AOA. So in stock condition, they can't be rotated to lift off at anywhere near stall speed. So, their minimum speed for takeoff is limited (made higher) by the length of the main gear legs. If the same trick is tried with 'short legs', the pilot would slam the tailwheel into the ground when he rotates. FWIW, there are videos of airliners actually dragging the rear of the fuselage on the ground when they over-rotate. Airliners (at least some of them) actually give up significant landing speed reduction because they don't want the weight of long gear legs when they always have plenty of runway for 'driving it on' in landing.



 



In landing mode, it's just as important. In normal flying, a pilot would try to '3 point', having the mains & tailwheel touch at the same time to land at minimum airspeed. But, since the wing isn't at critical AOA in 3 point attitude, he's not really landing at minimum airspeed. If the mains were longer, he could land slower. In bush flying, it gets worse. Again, watching extreme bush flying, you'll see the pilot wheel land and keep the tail off the ground until he's almost stopped. With a typical taildragger, he's carrying quite a bit of extra airspeed to 'wheel land' the plane, but he does it to protect the tailwheel from damage, from rough ground and from impact damage of dropping it in. If the legs are extended enough, he can have full stall AOA available from the wing, without the tailwheel being on the ground. Obviously, this will let him land slower & shorter.



 



Does any of that apply to Kolbs?



 

 



-- “Blessed are the cracked, for they shall let in the light.”   Groucho Marx

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Mon Mar 21, 2016 4:10 pm Post subject: long legs

Flying a Kolb with extra long spring steel gear legs is a no brainer.  It is easier to fly and ground handle than the original configuration.  With long legs one does not have to worry about nosing over, as much, which is very easy with regular length legs.  One does not have to be a s**t hot pilot to fly with long legs.



That all changed when we designed and built the new main gear for my MKIII.  By moving the axles 8" forward we placed about 100 lbs on the tail wheel which is stuck on the end of a long tail boom.  I have to stay on top of and ahead of my MKIII on the ground.  It is a real tail dragger with a lot of pendulum effect.  Took some getting used to initially, but has paid for itself many times over the last 3300+ hours.  Never been on its nose or even given a hint that it wanted to do such a nasty thing.



On the other hand, a friend with a RANS S7 landed on my 750' strip a couple weeks ago.  Got a little close to the end while turning around to take off.  Main wheel went into a depression and the RANs ate a 1300.00 WARP Drive prop in warp speed.



To maneuver on wet, rough, soft ground, and high weeds and brush, an aircraft has to have to ability to keep the tail on the ground when power is applied.  A pusher aircraft does nothing to help prevent this.  In fact, it helps you put you Kolb on its nose.  A tractor aircraft is pulling forward and up.  Our pushers are trying to rotate the Kolb around the axles and on its nose.



john h

mkIII

Fort Campbell, KY



--

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

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