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The Kolb drop
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jindoguy(at)gmail.com
Guest

Posted: Mon Feb 18, 2008 3:17 pm Post subject: The Kolb drop

I have been the victim of the Kolb "drop" more times than I care to admit. As I've said here before my intimate friendship with Mr. Hydraulic Press didn't end until Travis gave me the advice to wheel it on rather than trying to three point it. Now I carry 3000 RPM (750 prop RPM) all the way down to the deck then cut power and let her settle. It's pretty much the same technique I was taught for the Cessna 182. Works every time. Okay that and nerf tires work every time.

 So why does the Kolb (I can only speak of the Mk IIIC) have such an abrupt stall break? I'm no aerodynamicist,  but I can read a data plot of lift, drag, and center of pressure travel against angle of attack and I'll hazard a semi-educated opinion. 

 It's the leading edge radius and the flat bottom of the airfoil. The Kolb airfoil is about 12% thickness. Some have commented that it is of the TLAR variety and they may well be right. But if you pick up a copy of Michael Rice's little book, "Handbook of Airfoil Sections for Light Aircraft", there are several sections that closely resemble the Kolb's.

 Take a look at the NACA 66 of 1921 vintage. While the lift coefficient has a fairly gentle curve, the drag rise is very steep as it approaches stalling angle (figure 14 degrees AoA as the point where it most likely stalls) and look at the center of pressure curve, it's moving backward toward 40% as AoA increases, just as it would if you were holding the Kolb off by bringing the stick further and further back.  The result. Probably wham, and a visit with Mr. Press. Also take a look at the air speed at which the data was plotted, 98.4 feet per second (67.1 mph). Quite a bit faster than the generally agreed upon touch down speed of the Mk IIIC. No leading edge radius is given for the section, but its bottom is flat from 2.5 % of chord on back. By comparison the Kolb Mk III leading edge is 1.25% of chord (assuming a chord of 60" rather than counting the whole 64" as the aileron and flap leading edge thicken and lengthen out considerably)

 There's also the Clark Z from 1923. Similar to the NACA 66, but a slightly larger leading edge radius. This section was tested at 58.7 feet per second (40MPH) which is getting closer to the Kolb's drop speed , but look at the lift coefficient plot, it drops like a rock at 16 1/2 degrees AoA. Unfortunately there is no center of pressure plot for this section.

 If you want to go a bit farther afield, English investigators tested the Fage and Collins 3 in 1927 at 75 feet per second (51.2 mph). It's lift peaks at a bit more than 12 degrees and it's leading edge radius is a bit smaller than the Kolb's at .83%.

 The German's offer the Goettingen 285 and 365. Both are flat bottomed but the 285 has a larger leading edge radius and was tested at the slowest airspeed of the lot at 29.3 feet per second (20 mph). Unfortunately all it's data plots end at 15 degrees AoA. 

 The 365 had a small leading edge radius that is very close to the Kolb's at 1.26%, but like the NACA 66 it was tested at 98.4 feet per second (67.1 mph) Both these sections were of 1918/1919 vintage.

I also looked in Abbot and Von Doenhoff's "Theory of Wing Sections", but it deals with research from the late 20's to the late 40's and there are no flat bottomed sections listed.

 So, draw your own conclusions, do some more extensive research, or look around at the planes on the ramp the next time you go out to fly. It's not magic why the Kolb drops, but that's just my opinion.



Rick

 do not archive

  [quote][b]

John Hauck

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

Posted: Mon Feb 18, 2008 4:05 pm Post subject: The Kolb drop

Rick G:

  

 Pretty simple solution to Kolb QUIT.   

  

 Doesn't require a text book to  understand.

  

 Learn to fly the airplane.

  

 Every Kolb model I have flown, over the years,  lands the same way, with or without power, with or without flaps.   

  

 Learn to stall the airplane on the ground or a  couple inches above the ground.

  

 Or.............fly the airplane to the ground,  stick it there, and stop it.

  

 Most important is learn to fly it.

  

 john h

 mkIII

  

  

 [quote]    So, draw your own conclusions, do some    more extensive research, or look around at the planes on the ramp the next    time you go out to fly. It's not magic why the Kolb drops, but that's just my    opinion.



Rick

 

[b]

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

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Mon Feb 18, 2008 5:45 pm Post subject: The Kolb drop

At 06:15 PM 2/18/2008, Richard Girard wrote:



 	  Quote: 	
		  ...It's the leading edge radius and the flat bottom of the airfoil. The 

Kolb airfoil is about 12% thickness...


	


Any airfoil with a fairly sharp leading edge will have an fairly abrupt 

stall.  The flat bottom is irrelevant; it's just the product of the taper 

and thickness distribution (though like the leading edge chosen, no doubt, 

for ease of construction).  Combine the abrupt stall with a low mass / high 

drag aircraft and you get the behavior you see.



You don't want to flare too soon or high with a Quicksilver, either, or 

you'll be straightening or replacing the landing gear downtubes (been 

there, done that... once).



The test speeds for the other airfoils you mention has nothing to do with 

it (except perhaps for some minor Reynolds number effects).



-Dana



--

  The speed of light is greater than the speed of sound. That's why some 

people seem very bright until you hear them speak.

Steven Green

Joined: 05 Feb 2006
Posts: 118

Posted: Mon Feb 18, 2008 6:52 pm Post subject: The Kolb drop

I have experienced Kolb quit, Cessna quit, and  Piper quit.  They all plop down if your wheels are not on the ground when  they are through flying.  Some call it "quit".  I'll stick with  "stall".

 [quote]   Steven

   Mark III 912S

   550 hrs.

[b]

_________________
Steven Green

John Hauck

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

Posted: Mon Feb 18, 2008 7:10 pm Post subject: The Kolb drop

Steven G:

  

 Been sitting here waiting for your eloquent  response to a very simple question.

  

 Kolbs are simple little airplanes that are fun and  easy to fly.

  

 If folks would spend more time playing with their  Kolbs, rather than trying to tell others how to do it and why they do it, maybe  they would learn how to land them without the dreaded "Kolb quit".

  

 I shared this new expression with Homer Kolb.   Homer looked at me and gave me a big grin.

  

 john h

 mkIII - 

 [quote]    

   I have experienced Kolb quit, Cessna quit, and    Piper quit.  They all plop down if your wheels are not on the ground when    they are through flying.  Some call it "quit".  I'll stick with    "stall".

    	  Quote: 	
		       Steven

      

	
[b]

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

a58r(at)verizon.net
Guest

Posted: Mon Feb 18, 2008 7:15 pm Post subject: The Kolb drop

It ain't

The Drop,

It's tha

Sudden Stop.

bn



do not archive

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Tue Feb 19, 2008 5:34 am Post subject: Re: The Kolb drop

Kolb's have the characteristic of suddenly dropping hard on landing if very good technique is not used.  Cessna and other most other training aircraft are not like this, they are much more forgiving on landing and tolerant of the pilot being a little off speed, or a little high in the flare.  Only an idiot would not recognize there very real fact.   I have instructed in the Kolb, and as a CFI in general aviation aircraft.  In General aviation aircraft, I can let students get much further off speed, or flare a lot higher on landing than in a Kolb, and not bend the gear or result in a very hard landing.   Hundreds of students flare high, land slow, etc etc every day in Cessnas and other aircraft and you do not constantly bend the gear, partly due to stronger gear, and partly to do much more forgiving aerodynamics.



The other fact is that on my Kolb MK III, VG's have done a lot to correct this bad habit of dropping suddenly and hard upon landing.  VG's do not solve this problem entirely, but my Kolb MK III is not anywhere near as critical in landing as it was, and it does not drop nearly as hard if I am a few feet high as it did without VG's.  I don't care so much about the theory, or what some may say about stalls, the FACT is that VG's make landings much easier and less critical in my Kolb, and that is a great thing.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

ez(at)embarqmail.com
Guest

Posted: Tue Feb 19, 2008 6:17 am Post subject: The Kolb drop

On Feb 19, 2008, at 8:34 AM, JetPilot wrote:



 	  Quote: 	
		   Only an idiot would not recognize there very real fact.


	




<  Smile  >

ez(at)embarqmail.com
Guest

Posted: Tue Feb 19, 2008 6:28 am Post subject: The Kolb drop

On Feb 19, 2008, at 8:34 AM, JetPilot wrote:



 	  Quote: 	
		    If you have no fear you did not go as fast as you could have !!!


	




If you are not yet an idiot ,,,,,,,,,, your ego in not the size it  

could be !!!

ElleryWeld(at)aol.com
Guest

Posted: Tue Feb 19, 2008 6:39 am Post subject: The Kolb drop

there must be some here then,  not pointing any  fingers at anyone special just making a statement  

  

 Ellery 

 do not archive

  

  In a message dated 2/19/2008 9:18:14 A.M. Eastern Standard Time,  ez(at)embarqmail.com writes:

  	  Quote: 	
		  -->    Kolb-List message posted by: Eugene Zimmerman    <ez(at)embarqmail.com>

On Feb 19, 2008, at 8:34 AM, JetPilot    wrote:



 	  Quote: 	
		   Only an idiot would not recognize there very real    fact.


	




<  Smile  >    es  y       -->                 - MATRONICS WEB FORUMS  nbsp;               - List Contribution Web Site  ;                             =========================



	




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lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Tue Feb 19, 2008 6:40 am Post subject: Re: The Kolb drop

 	  JetPilot wrote: 	
		  Kolb's have the characteristic of suddenly dropping hard on landing if very good technique is not used.  Cessna and other most other training aircraft are not like this, they are much more forgiving on landing and tolerant of the pilot being a little off speed, or a little high in the flare.  Only an idiot would not recognize there very real fact.   I have instructed in the Kolb, and as a CFI in general aviation aircraft.  In General aviation aircraft, I can let students get much further off speed, or flare a lot higher on landing than in a Kolb, and not bend the gear or result in a very hard landing.   Hundreds of students flare high, land slow, etc etc every day in Cessnas and other aircraft and you do not constantly bend the gear, partly due to stronger gear, and partly to do much more forgiving aerodynamics.



The other fact is that on my Kolb MK III, VG's have done a lot to correct this bad habit of dropping suddenly and hard upon landing.  VG's do not solve this problem entirely, but my Kolb MK III is not anywhere near as critical in landing as it was, and it does not drop nearly as hard if I am a few feet high as it did without VG's.  I don't care so much about the theory, or what some may say about stalls, the FACT is that VG's make landings much easier and less critical in my Kolb, and that is a great thing.



Mike 	




Don't mean to jump in, but this is describing more a general characteristic of (comparatively speaking) high-drag/low-inertia designs like the Kolb and not really a unique characteristic of the Kolb. 



In fact, I found the FS II I had required energy management techniques virtually identical to the other UL/UL-like designs I've flown over the years. The closest analog for me was my quicksilver (MX Super); it flew so close to that plane that basically, as soon as I got used to the ground handling and tailwheel aspect, I was off going around the pattern practicing my wheel landings.



As for the "drop", which is indeed only a euphemism for stalling the wing more than a couple inches above the ground, the FSII behaved virtually identically to my quicksilver in this respect. On the quick, of course, you're off to the hangar to replace the axle and possibly the landing gear down tubes at that point, but the Kolb is a little more durable, especally mine was because it had large tundra-like tires on the mains.



My fun racer trike with the double surface wing would also exhibit the "drop" as it had a similar fairly abrupt stall break and could be subject to the hazard of the "drop".



But I never broke anything on the trike either. It could have have been that I'm just so used to flying low-inertia designs that I remained well clear of hazardous "drops" as best I could (I also wheel landed the FSII about 95% of the time and only attempted 3 points in very calm weather).....



In any case, I found the Kolb gave no surprises, at least not to me, compared to any other similar planes I"d flown.  I can't think of any kind of situation where the Kolb would lead to bent gear legs more (or less!) than any other light aircraft. 



As for training, the low-inertia aspect is the hardest one for pilots transitioning from general aviation to get a handle on. Controlling the plane in the air, takeoffs and so on are pretty easy, but landings (particularly the energy management part) can yield a pretty sweaty and cursing student for several hours at least.



Don't ask me how I know this is the case.



Finally, FWIW, I believe I recall being able to get the C150 to do the "drop", but it required a low pass with no flaps in the flare attitude with progressively more back elevator and reducing throttle. 



The titan tornado will also do the drop, but it' stall AOA is also very high in the flare and it also requires a lot of coaxing (and stupidity) to get it to do it (and generally you bang the tailwheel down in the process).



LS

_________________
LS
Titan II SS

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Tue Feb 19, 2008 9:43 am Post subject: The Kolb drop

At 08:34 AM 2/19/2008, JetPilot wrote:



  	  Quote: 	
		  Kolb's have the characteristic of suddenly dropping hard on landing if very good technique is not used.  Cessna and other most other training aircraft are not like this, they are much more forgiving on landing... 	


 All this talk makes me wonder... how many of the people on this list came from a GA background, and learned to fly in a Cessna or similar, and how many came from an ultralight background?  I'd bet it's only the Cessna drivers that have problems with the so called "Kolb quit", which is common to all ultralights (I know a MLIII isn't an ultralight, but it's certainly descended from one).



 My old Taylorcraft required me to start my flare before I even got over the runway threshold, if I didn't want to float half way down the runway.  This gave me some trouble at first when I got back into flying in a Quicksilver, which like a Kolb, has to be flown right down to the ground.  After a few hours in the Quick, my Kolb gave me no trouble at all.



 This is nothing new; Homer knew it well.  From the original UltraStar manual:

           "Many airplane pilots have flown the UltraStar for the first time and had no difficulties.  



          "However, if pilots do have any trouble ut is usually in the landing department.  All proceeds well until it its time to flare for landing; a typical airplane has much more weight than an ultralight, and has much less drag than a typical ultralight does.  An airplane comes in twice as fast as a typical ultralight.  An airplane therefore has many times the energy to dissipate than a typical ultralight has, and less drag to help dissipate it.  A typical landing flare in an airplane will start much higher than an ultralight because it has plenty of momentum to dissipate before touching down.



          "Thus when an airplane pilot gets into an ultralight, what can happen is that the [airplane oriented] pilot tends to start to flare too high in the air, he then stalls 10 to 15 feet above the runway and lands quite hard which usually will collapse the landing gear... the safest way to avoid this is to carry some power... you should fly the UltraStar onto the ground..."



  -Dana

 --

  "If yew ain't livin' on th' edge, yer takin' up too much room!"    [quote][b]

slyck(at)frontiernet.net
Guest

Posted: Tue Feb 19, 2008 10:56 am Post subject: The Kolb drop

Dana,  sure is true about the Taylorcraft.  A great little plane, floats and floats and floats.............

My Kolb has a beneficial side however, as when I get an occasional gust just before touchdown that lifts us

10' above the hard stuff.  In a more conventional tractor high wing craft a sudden addition of power at this

point will rotate the nose up, putting you in a worse attitude unless you (after some misadventures) push the

stick forward simultaneously.

In the Kolb all this happens automatically when the pusher prop adjusts things quite nicely for you.



All old geezers should have a Kolb to fly.

BB

do not archive

On 19, Feb 2008, at 12:38 PM, Dana Hague wrote:

[quote] At 08:34 AM 2/19/2008, JetPilot wrote:



  	  Quote: 	
		  Kolb's have the characteristic of suddenly dropping hard on landing if very good technique is not used.  Cessna and other most other training aircraft are not like this, they are much more forgiving on landing... 	


 All this talk makes me wonder... how many of the people on this list came from a GA background, and learned to fly in a Cessna or similar, and how many came from an ultralight background?  I'd bet it's only the Cessna drivers that have problems with the so called "Kolb quit", which is common to all ultralights (I know a MLIII isn't an ultralight, but it's certainly descended from one).



 My old Taylorcraft required me to start my flare before I even got over the runway threshold, if I didn't want to float half way down the runway.  This gave me some trouble at first when I got back into flying in a Quicksilver, which like a Kolb, has to be flown right down to the ground.  After a few hours in the Quick, my Kolb gave me no trouble at all.



 This is nothing new; Homer knew it well.  From the original UltraStar manual:

          "Many airplane pilots have flown the UltraStar for the first time and had no difficulties.  



         "However, if pilots do have any trouble ut is usually in the landing department.  All proceeds well until it its time to flare for landing; a typical airplane has much more weight than an ultralight, and has much less drag than a typical ultralight does.  An airplane comes in twice as fast as a typical ultralight.  An airplane therefore has many times the energy to dissipate than a typical ultralight has, and less drag to help dissipate it.  A typical landing flare in an airplane will start much higher than an ultralight because it has plenty of momentum to dissipate before touching down.



         "Thus when an airplane pilot gets into an ultralight, what can happen is that the [airplane oriented] pilot tends to start to flare too high in the air, he then stalls 10 to 15 feet above the runway and lands quite hard which usually will collapse the landing gear... the safest way to avoid this is to carry some power... you should fly the UltraStar onto the ground..."



  -Dana

 --

  "If yew ain't livin' on th' edge, yer takin' up too much room!"  	  Quote: 	
		  

href="http://www.matronics.com/Navigator?Kolb-List">http://www.matronics.com/Navigator?Kolb-List

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href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	
[b]

Possums

Joined: 03 Nov 2007
Posts: 247

Posted: Tue Feb 19, 2008 2:55 pm Post subject: The Kolb drop

At 12:38 PM 2/19/2008, you wrote:

  	  Quote: 	
		  At 08:34 AM 2/19/2008, JetPilot wrote:



  	  Quote: 	
		  Kolb's have the characteristic of suddenly dropping hard on landing if very good technique is not used.  Cessna and other most other training aircraft are not like this, they are much more forgiving on landing... 	


 All this talk makes me wonder... how many of the people on this list came from a GA background, and learned to fly in a Cessna or similar, and how many came from an ultralight background?  I'd bet it's only the Cessna drivers that have problems with the so called "Kolb quit", which is common to all ultralights (I know a MLIII isn't an ultralight, but it's certainly descended from one). 	


 I think that's exactly what the problem is.  You cannot make a Cessna driver fly a kolb to the ground

 no matter how many times you tell him. He will always flare too high. 

 Only bending the landing gear will "eventually" convince a GA pilot that it will stop flying when you

 pull back the throttle and flare a kolb.  If they've never flown anything, it is easier.     [quote][b]

_________________
Possum

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Tue Feb 19, 2008 3:25 pm Post subject: The Kolb drop

At 01:53 PM 2/19/2008, robert bean wrote:



 	  Quote: 	
		  My Kolb has a beneficial side however, as when I get an occasional gust 

just before touchdown that lifts us

10' above the hard stuff.  In a more conventional tractor high wing craft 

a sudden addition of power at this

point will rotate the nose up, putting you in a worse attitude unless you 

(after some misadventures) push the

stick forward simultaneously.

In the Kolb all this happens automatically when the pusher prop adjusts 

things quite nicely for you.


	


Except in my UltraStar... the engine is much lower than the other Kolb 

designs, so it behaves like a more conventional airplane.



-Dana

--

  The two most common elements in the Universe are hydrogen and stupidity.

Steve Boetto

Joined: 11 Jan 2006
Posts: 365

Posted: Tue Feb 19, 2008 6:17 pm Post subject: The Kolb drop

Only an idiot would not recognize there very real fact.   I have  instructed in the Kolb, and as a CFI in general aviation aircraft. 

  

  

 That's it, I've had it, time to unplug for a  while.

  

 Steve

  

  In a message dated 2/19/2008 8:37:52 A.M. Eastern Standard Time,  orcabonita(at)hotmail.com writes:

  	  Quote: 	
		  -->    Kolb-List message posted by: "JetPilot"    <orcabonita(at)hotmail.com>



Kolb's have the characteristic of    suddenly dropping hard on landing if very good technique is not used.     Cessna and other most other training aircraft are not like this, they are much    more forgiving on landing and tolerant of the pilot being a little off speed,    or a little high in the flare.  Only an idiot would not recognize there    very real fact.   I have instructed in the Kolb, and as a CFI in    general aviation aircraft.  In General aviation aircraft, I can let    students get much further off speed, or flare a lot higher on landing than in    a Kolb, and not bend the gear or result in a very hard landing.      Hundreds of students flare high, land slow, etc etc every day in Cessnas and    other aircraft and you do not constantly bend the gear, partly due to stronger    gear, and partly to do much more forgiving aerodynamics.



The other fact    is that on my Kolb MK III, VG's have done a lot to correct this bad habit of    dropping suddenly and hard upon landing.  VG's do not solve this problem    entirely, but my Kolb MK III is not anywhere near as critical in landing as it    was, and it does not drop nearly as hard if I am a few feet high as it did    without VG's.  I don't care so much about the theory, or what some may    say about stalls, the FACT is that VG's make landings much easier and less    critical in my Kolb, and that is a great    thing.



Mike



--------

&quot;NO FEAR&quot; -  If    you have no fear you did not go as fast as you could have !!!



Kolb    MK-III Xtra, 912-S





Read this topic online    here:



http://forums.matronics.com/viewtopic.php?p=164998#164998

	




Delicious ideas to please the pickiest eaters. Watch the video on AOL Living.

russ(at)rkiphoto.com
Guest

Posted: Tue Feb 19, 2008 6:26 pm Post subject: The Kolb drop

I hate to see blame thrown where it shouldn't  be thrown.Of course it shouldn't be called the "Kolb drop"; no need blaming the Kolb design for a perfectly normal flight occurrence. It's simply a stall, and ALL wings will stall. All pilots should feel this out, at a safe altitude. 

Basically, the heavier the aircraft, the higher speed at which it will stall, and the earlier you should start your flare. (BTW, it's 'flare', not flair). I fly would a twin Otter or DC-3 much differently than I would a Cub or Champ. Huge weight difference.Wing design  is also a  factor. Wing 'washout' or 'twist' reduces the abruptness of the stall, delays it and  makes it gentler. Worst I ever flew was the BD-4, whose wing has NO washout at all. One minute it was flying, then the next second --WHAM ! it was nose-down, headed toward the ground. Scary.

They're all similar, but all different. 

Learn to fly your aircraft!. 

I'm sure Kolbs are no worse than  the others. Just different.



 [quote][b]

jbhart(at)onlyinternet.ne
Guest

Posted: Wed Feb 20, 2008 7:21 am Post subject: The Kolb Drop

Kolbers,



I wondered about the term Kolb Drop.  Is it fair or proper to give Homer 

credit for this phenomenon? I checked the FAA Preliminary Accident and 

Incident Reports for Feb 19.  Out of 38 reports, I found five were listed as 

outright crashes while the aircraft was away from an airport.  The 

transition from the air to the ground and movement on the ground seems to 

give pilots a lot of trouble.  Eight pilots had trouble keeping their 

aircraft aligned properly with the runway which resulted in nose overs, 

ground loops, slide offs, hitting snow banks and taxiing problems that 

killed several runway marker lights.  Birds sacrificed them selves to three 

aircraft.  And finally, eight pilots impacted their aircraft so hard that 

only three could taxi away from the runway.  Not one of these aircraft was 

listed as a Kolb. These data indicate that it must be more difficult to land 

and taxi GA and commercial aircraft than Kolb designed aircraft.



May be Kolb Drop should be redefined as Earth Jump.  Earth Jump can be 

equally applied to all aircraft with out giving undue credit and it easily 

explains away why the earth is not in the correct position when these pilots 

flared or were repositioning their aircraft.



All aircraft are equal when they are on the ground and humans are absent.  

The snow is slowly falling.  Fly safe.



Jack B. Hart FF004

Winchester, IN



do not archive 






Only an idiot would not recognize there very real fact.   I have instructed in the Kolb, and as a CFI in general aviation aircraft. 

..............

Kolb's have the characteristic of suddenly dropping hard on landing if very good technique is not used.  Cessna and other most other training aircraft are not like this, they are much more forgiving on landing and tolerant of the pilot being a little off speed, or a little high in the flare.  Only an idiot would not recognize there very real fact.   I have instructed in the Kolb, and as a CFI in general aviation aircraft.  In General aviation aircraft, I can let students get much further off speed, or flare a lot higher on landing than in a Kolb, and not bend the gear or result in a very hard landing.   Hundreds of students flare high, land slow, etc etc every day in Cessnas and other aircraft and you do not constantly bend the gear, partly due to stronger gear, and partly to do much more forgiving aerodynamics.

John Hauck

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

Posted: Wed Feb 20, 2008 7:37 am Post subject: The Kolb Drop

> May be Kolb Drop should be redefined as Earth Jump.  Earth Jump can be

 	  Quote: 	
		   equally applied to all aircraft with out giving undue credit and it easily

 explains away why the earth is not in the correct position when these 

 pilots

 flared or were repositioning their aircraft.


	


 	  Quote: 	
		   Jack B. Hart FF004


	




Jack H:



I like that explanation.



I'm sure Kolb Quit could not be related to pilot technique.  



john h

mkIII

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

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Wed Feb 20, 2008 8:46 am Post subject: Re: The Kolb drop

Now that I have finished laughing at all the threads and fuss over a simple stall I think I'll put in my 2 cents as well.



- Don't stall your Kolb at any height you don't want to drop from.



- Vortex generators would be a fun and helpful addition to your Kolb if you want to mellow the stall a bit and buy some more time to recover from a misjudged flair(stall).



- If you don't know what a stall is and how to handle it then its time to visit a good certified instructor and update your insurance policy before doing any more piloting.



I think the main problem here is that the Kolb drop is not recognized for what it really is....the wing quits generating sufficient lift and is stalled....plain and simple.



The difference between a Kolb and heavier aircraft is that it slows down a lot quicker, so you do not need to flair as early or as high as with the heavier aircraft.



An extreme example would be the space shuttle landings.....they pitch the shuttle up to start the flair for landing a half mile away from the intended touch down point.



Also the Kolb does NOT have shock absorbing landing gear, so you do not want to subject it to a full stall landing from any height as dropping it in is going to hurt the Kolb and perhaps the pilot.



Nuff Said....get used to your Kolb and fly it accordingly.



If you keep doing something painfull...then STOP doing it and try something else.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

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