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Conventional Vs Tail and other training

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Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Nov 27, 2006 7:19 am Post subject: Conventional Vs Tail and other training

The tricycle gear handles differently no doubt....  But directionally more

stable.  I think directional stability will be the result of a number of

factors. E.g. the speed of taxi, the number of wheels on the ground, the

direction and speed of the wind, the condition and length of the runway and

lets not forget the experience of the pilot.



What I find interesting is the fact that in this country we don't have a

tail wheel endorsement and it seems we also don't have the perceived

problems of flying with one.  I am in favour of additional training where it

is needed and additional training on the tail wheel is probably a good idea.

For pilots who have only flown with the conventional gear some training in

the tricycle config. Would also be a good idea.  There are manoeuvres used

on tricycle gear that do not even exist on conventional aircraft.  E.g. soft

field taxiing.  I'm willing to bet there are people who are reading this

list who have had at least one accident involving a tricycle/conventional

gear plane on a runway.



In this country, now, you don't have to do any spirals, the recover from

which can seriously twist your plane, if done incorrectly.  You also don't

have to do any spins the recovery from which is mandatory to a good day.  I

don't know if this is true south of the 49th but up this way it appears that

TC ( Transport Canada ), the governing body wants people to have their

crashes away from the airports.  I think that spiral and spin training would

be at least as important as training on conventional gear.



The above in reference to the safe operation of Kitfox aircraft. 



Fly fish, Fly floats, Fly Safe!



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

MichaelGibbs(at)cox.net
Guest

Posted: Tue Nov 28, 2006 9:02 am Post subject: Conventional Vs Tail and other training

Noel sez:



 	  Quote: 	
		  I think directional stability will be the result of a number of 

factors. E.g. the speed of taxi, the number of wheels on the ground, 

the direction and speed of the wind, the condition and length of the 

runway and lets not forget the experience of the pilot.


	


You are describing the factors that affect controllability, not 

stability.  According to the Webster's dictionary, stability is, 

"...the property of a body that causes it, when disturbed from a 

condition of equilibrium or steady motion, to develop forces or 

moments that restore the original condition..."



Just as you want the airplane's center of pressure (or surface area) 

behind the center of mass to make it stable in pitch and yaw during 

flight, you need the non-turning wheels behind the center of mass to 

make it stable on the ground.  Directional stability has only to do 

with the relationship between the main (or non-turning) gear and the 

center of mass.  Main gear behind the center of mass = stable, main 

gear in front of the center of mass = unstable.



If the wind displaces the tail end of a tail dragger to one side, it 

takes positive action on the part of the pilot to bring it back 

straight--the airplane wants to continue on around rather than 

straighten out.  A nose wheeled airplane that is displaced in the 

same way tends to straighten out (not necessarily staying on the 

runway, mind you).



I wasn't saying that a tail wheel airplane is uncontrollable 

(obviously!), just that they are not directionally stable.  This 

instability means that the pilot must actively control the direction 

of the airplane at all times, i.e., you have to fly it all the way to 

the hangar, as it were.



Mike G.

N728KF

Fox5flyer
Guest

Posted: Tue Nov 28, 2006 11:53 am Post subject: Conventional Vs Tail and other training

Good explanation Mike.  That's about as clear and simple as one could make

it.

Thanks,

Deke

do not archive

Michael said...



 	  Quote: 	
		  

 You are describing the factors that affect controllability, not

 stability.  According to the Webster's dictionary, stability is,

 "...the property of a body that causes it, when disturbed from a

 condition of equilibrium or steady motion, to develop forces or

 moments that restore the original condition..."



 Just as you want the airplane's center of pressure (or surface area)

 behind the center of mass to make it stable in pitch and yaw during

 flight, you need the non-turning wheels behind the center of mass to

 make it stable on the ground.  Directional stability has only to do

 with the relationship between the main (or non-turning) gear and the

 center of mass.  Main gear behind the center of mass = stable, main

 gear in front of the center of mass = unstable.



 If the wind displaces the tail end of a tail dragger to one side, it

 takes positive action on the part of the pilot to bring it back

 straight--the airplane wants to continue on around rather than

 straighten out.  A nose wheeled airplane that is displaced in the

 same way tends to straighten out (not necessarily staying on the

 runway, mind you).



 I wasn't saying that a tail wheel airplane is uncontrollable

 (obviously!), just that they are not directionally stable.  This

 instability means that the pilot must actively control the direction

 of the airplane at all times, i.e., you have to fly it all the way to

 the hangar, as it were.



 Mike G.

 N728KF

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Nov 28, 2006 12:07 pm Post subject: Conventional Vs Tail and other training

I agree with your definition of stability.  At low speed  with little or no

cross wind I think the conventional gear will be more stable simply because

the thrust coming from in front of the centre of mass works to stabilize the

plane and the increase in the distance between the mains and the steering

wheel (wheel base) being longer the conventional gear should be more stable.

At somewhat higher speed when a tricycle gear plane may have its nose wheel

off the ground, as in soft field operation and a conventional gear plane may

have its tail up then both planes will display very similar stabilities.



Only when the conventional gear is slowing down, as in landing, and the tail

is still off the ground is the operational stability marginally lower than

the a comparable tricycle plane.  What are we talking about here two or

three seconds of a flight? 



Yes there are places where a tricycle plane is more stable than a

conventional.  Slow taxi in a strong cross wind is one. But the tail dragger

is more stable taxiing down wind than the tricycle.  



Visibility is a bit better in the tricycle Kitfox than the conventional gear

Kitfox.  But if you bring your tricycle gear 'Fox that close to the back of

my plane you are too darn close!   Let's face it we don't have the visual

problems that the old war birds like the avenger had.  The problem that Air

Venture had last summer wouldn't have happened if the plane in the back had

been a bit smaller.  That problem was only partially caused by the tail

dragger...  Pilot distraction is probably more to blame.



What I really disagree with is the picture painted of every conventional

gear plane being some sort of dragon that must be slain or at least tamed.

At the same time tricycle gear planes are painted to be almost auto-landing

super safe (that in itself may make them more dangerous and lead to ground

accidents).  By the way, "auto-landing", I think you will find, is what

Cessna called their first tricycle gear planes.



Either way these are great planes.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

MichaelGibbs(at)cox.net
Guest

Posted: Wed Nov 29, 2006 7:33 pm Post subject: Conventional Vs Tail and other training

Noel sez:



 	  Quote: 	
		  I agree with your definition of stability. At low speed with little 

or no cross wind...thrust coming from in front of the centre of 

mass...At somewhat higher speed when a tricycle gear plane may have 

its nose wheel off the ground...and a conventional gear plane may 

have its tail up then both planes will display very similar 

stabilities.


	


You say you agree with the definition of stability and yet you didn't 

get it at all.  Lifting the nose or tail wheel has nothing to do with 

stability but it does have something to do with controlability. 

Stability has only to do with the relationship between the pivot 

point--the main landing gear in this case--and the center of mass. 

It has nothing to do with engine power or air over the tail or 

speed--these all affect controlability, not stability.



There are plenty of controlable vehicles that are unstable. 

Bicycles, for example are very unstable yet most of us find them easy 

to control.  Without active input from a pilot, though, the bike 

falls right over.  That said, we all know it takes some practice and 

a few spills to master the balance required to ride one.



 	  Quote: 	
		  What I really disagree with is the picture painted of every 

conventional gear plane being some sort of dragon...[and] tricycle 

gear planes are painted to be almost auto-landing super safe...


	


I hope you aren't saying that I made either of those claims.



Mike G.

N728KF

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Thu Nov 30, 2006 6:50 am Post subject: Conventional Vs Tail and other training

Let me get this straight ... A vehicle with a high centre of gravity on a

short wheel base is more stable than the same machine configured with a

longer wheel base and a lower centre of gravity.



Ok I got it ....Not!



 	  Quote: 	
		   Stability has only to do with the relationship between the pivot

point--the main landing gear in this case--and the centre of mass.
	




I think you are over simplifying things.  I will agree that the tricycle

plane will have more longitudal stability than its conventional counterpart

but only for the few seconds after touch down.  After that it depends on

many other factors.  



The conventional aircraft is only less stable for a few seconds of every

flight and yes that is more than enough time to have an accident.  The

tricycle gear also has seconds of instability  especially taxiing downwind

with the wind to either aft quarter and that is either a high speed or low

speed taxi.



As for the bicycle if you spin the wheels fast enough it will stay up on

it's own.  



And slaying the dragon I was referring to the consensus which seems to be

displayed by tricycle operators.  Not necessarily every tricycle operator

and not any particular operator.



I notice no one has said anything about the numbers of ground accidents

involving tricycle vs. conventional gear planes.  From that there are only

two deductions ...  They all have accidents or there are no accidents.

Either way it would indicate neither configuration is more stable.



Me......



I fly floats.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Nov 30, 2006 7:01 am Post subject: Conventional Vs Tail and other training

I would assume that most  ground handling  accidents are 99.9 % pilot error 

no matter what the gear config is .

Some can fly taildraggers and some cannot not it seems.

All personal preferance from my viewpoint but that being said I am sure that 

there is a far greater amount of taildragger Kitfoxes produced and a small 

percentage  that cannot physically or have the desire to fly them so they 

opt for a tri- gear.



Taildragger Kitfox is a very tame aircraft to fly, it is the pilot that is 

not competant that does not like them.



Can we end this topic now ?



Dave





---

_________________
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http://www.youtube.com/user/kitfoxflyer
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GENTRYLL(at)aol.com
Guest

Posted: Thu Nov 30, 2006 7:08 am Post subject: Conventional Vs Tail and other training

This question is kind of an offshoot of the current topic.  I would  like to ask those of you that have a lot of Kitfox or other light taildragger  time, if a noticeable difference in horsepower of say a 65 hp. 582 and a 100 hp  Subaru cause's a noticeable difference in rudder control due to the difference  in torque.

  [quote][b]

lcfitt(at)sbcglobal.net
Guest

Posted: Thu Nov 30, 2006 7:21 am Post subject: Conventional Vs Tail and other training

Mike,



A bit ago you intruduced the center of pressure into the stability equation. 

I am totally confused now.  Isn't the center of pressure a factor when 

moving on the ground as well as in the air?



Lowell



---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Thu Nov 30, 2006 7:45 am Post subject: Conventional Vs Tail and other training

My sentiments exactly.... Especially the last one.



Do not archive



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

smokey_bear_40220(at)yaho
Guest

Posted: Thu Nov 30, 2006 9:58 am Post subject: Conventional Vs Tail and other training

I got my TW endorsement in a KF-4 with a 100 hp NSI

Soob.  It was amazing to me how this plane wanted to

make a 15 degree right turn as I raised the tail on

takeoff and then a left turn as I rotated for lift

off.  Very pronounced tendency.  It was much easier to

land than takeoff.



I was really worried when I first flew my S-5 with the

140 hp NSI in it.  I expected an even worse turn to

correct for as I changed the plain of rotation of the

big gyroscope out front.  Instead it had almost no

turning tendancy at all.  Well, maybe 1/3 of the

tendancy of the S-4.



I think there are more factors than hp at play here,

like prop size and weight, rpm, and aircraft geometry.



My friends tell me that the newer Maules are the worst

plane on the ground that they fly.  The big tails and

relatively smaller rudders make them want to turn into

the wind more and give you less power to stop that. 

This is where stability works against you and more

controlability would be helpful.



The whole discussion of controlability and stability

is about twice as complex as so far covered.  You have

ground stability and aerodynamic stability.  You have

ground controlability and aerodynamic controlability. 

Then brakes, wheel alignment, adverse yaw and other

factors to consider.



Pilotage:  If you normally react to a ground loop by

moving the stick to hold the outside wing up, in a KF

your adverse yaw will help you control the plane.  If

you normally move the stick with the rudder to keep

the plane from turning, you will make it ground loop

worse.  You may not even know which you do, since most

people concentrate on what they are doing with the

rudder on the ground.



There is so much more to this that it is very

extensive to get into.  But I think the origional

topic is more of, which do you like and what can I

handle?  Stick shift or automatic?



I agree with the idea of trying both enough to be

profficient, then choosing the one you like.  The rest

is pride.



Kurt S.  S-5 KitFox (N-210F "Heavy")



--- GENTRYLL(at)aol.com wrote:



 	  Quote: 	
		   This question is kind of an offshoot of the current

 topic.  I would  like to 

 ask those of you that have a lot of Kitfox or other

 light taildragger  time, 

 if a noticeable difference in horsepower of say a 65

 hp. 582 and a 100 hp  

 Subaru cause's a noticeable difference in rudder

 control due to the difference in torque.

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Thu Nov 30, 2006 10:14 am Post subject: Conventional Vs Tail and other training

kurt



would  you contribute that to asseymetrical thrust and P  factor ?



Dave

---

smokey_bear_40220(at)yaho
Guest

Posted: Thu Nov 30, 2006 11:41 am Post subject: Conventional Vs Tail and other training

Hi Dave,



Actually neither of those were primary in that KF-IV

case.  The NSI prop turns CCW, so it takes left rudder

to fight P factor and it would turn right as you power

up.  The rotating wind behind the prop would push the

tail left - nose right.  Yes, that happens, but not

changing at tail lift or rotation.



Torque in the CCW rotation case makes the plane turn

right too.  Once your rpms are up, I think you've

adjusted for it and the other forces make primary

changes.



Asseymetrical thrust does change at rotation, but in

the NSI case, it turns left as the tail comes up

because the downward moving blade loses thrust on the

left side and the upward moving blade increases thrust

on the right side.



The big factor for that plane was gyroscopic - a big

right turn as you lift the tail and a left turn at

liftoff.  And from the inside the prop really looked

big too.



You've got all 4 forces at work and some against the

other.  And they change as you accellerate and rotate.

 The plane goes with the winner of the moment.



I suppose in the big war birds, torque at powerup, P

factor as you rolled, followed by gyroscopic and

assymetrical thrust at tail lift and rotation keep

them dancing on the pedals.



When I did my spins during testing, I found the

spinner back contacted the cowl due to the gyroscope

forces, even at idle rpm, during those spins.  It is

the only time my cowl took a hit in all my maneuvers.



Kurt S.



--- dave <dave(at)cfisher.com> wrote:



 	  Quote: 	
		   kurt

 

 would you contribute that to asseymetrical thrust

 and P factor ?

 

 Dave


	




 

Cheap talk?

MichaelGibbs(at)cox.net
Guest

Posted: Fri Dec 01, 2006 8:40 am Post subject: Conventional Vs Tail and other training

Noel sez:



 	  Quote: 	
		  Let me get this straight...A vehicle with a high centre of gravity 

on a short wheel base is more stable than the same machine 

configured with a longer wheel base and a lower centre of gravity.


	


We are talking about directional stability here, Noel, not lateral. 

How high the thing sits has nothing to do with directional stability. 

Here's an experiment for you to conduct:



Go down to the local grocery store and grab a shopping cart that's in 

reasonably good shape.  Give it a push across the parking lot 

(watching out for parked cars, of course) and see how it travels. 

Now take the same cart and turn it around backward and give it a 

shove.  This time it will flip around forward on its own.



Now, fill the cart with a heavy load of groceries and do both test 

runs again.  You'll see that the cart still continues straight when 

pushed forward and still flips around when pushed backward.  The 

higher load makes no difference.



Now go to your local Home Depot or Lowes or hardware store and get 

one of those flat carts used for hauling bricks and lumber (NOT one 

with wheels mounted in the MIDDLE, it must have FIXED wheels at one 

end and SWIVEL wheels at the other end).  Push one of these both 

forward and back and you'll see it stay straight when the swivel 

wheels are in the front and it will flip around when the swivel 

wheels are in back.  Now load this one up with a bunch of heavy 

stuff--no change!



 	  Quote: 	
		  I will agree that the tricycle plane will have more longitudal 

stability than its conventional counterpart but only for the few 

seconds after touch down.


	


As I've said repeatedly, you are talking about CONTROLABILITY.  I am 

talking about STABILITY.  They are NOT the same thing.



 	  Quote: 	
		  The conventional aircraft is only less stable for a few seconds...


	


It is ALWAYS unstable by definition.  I hope after conducting the 

shopping cart experiment you'll understand that.



 	  Quote: 	
		  As for the bicycle if you spin the wheels fast enough it will stay 

up on it's own.


	


It seems like you are trying very hard to NOT understand the 

underlying concept of stability.  Try another experiment:  go out and 

push the bicycle as fast as you or the kid down the block can 

POSSIBLY push it and see if that is enough to keep it upright.  My 

point was that even though the bike (at reasonable speeds) wants to 

fall over, the rider can easily CONTROL it even though it is UNSTABLE.



 	  Quote: 	
		  I notice no one has said anything about the numbers of ground 

accidents involving tricycle vs. conventional gear planes.


	


I am quite certain that if I invested the considerable amount of time 

required to show that, per capita, there are more 

loss-of-control-on-the-ground accidents in tail draggers you would 

dispute the source of the data, dispute what constitutes a loss of 

control, and dispute the experience and qualifications of the pilots 

involved and go on believing that since you are able to CONTROL a 

tail dragger it must be stable.



Mike G.

N728KF

MichaelGibbs(at)cox.net
Guest

Posted: Fri Dec 01, 2006 8:41 am Post subject: Conventional Vs Tail and other training

Lowell asks:



 	  Quote: 	
		  A bit ago you intruduced the center of pressure into the stability 

equation. I am totally confused now. Isn't the center of pressure a 

factor when moving on the ground as well as in the air?


	


It is a factor, Lowell, but when the airplane is on the ground it 

cannot pivot around the center of pressure like it would in 

flight--it will always pivot around the main gear (unless you are 

skidding the wheels, of course).



So, in flight, the center of mass is forward of the pivot point 

(center of pressure), giving the airplane positive yaw stability.  On 

the ground, a tail dragger's pivot point is now the main gear, which 

is in forward of the center of mass, causing negative stability.  A 

tricycle gear airplane's pivot point is also the main gear, but they 

are still behind the center of mass, therefore it has positive 

stability.



Mike G.

N728KF

aldaniels(at)fmtcblue.com
Guest

Posted: Mon Dec 04, 2006 10:04 pm Post subject: Conventional Vs Tail and other training

Its nice to see familiar names on the list as I have been off for half a 

year due to work. This thing about which end the little wheel should be 

on comes up every year or so. We fly these things for fun so put it 

where you want it. The only real reason to put it on the back is for 

landing soft or rough, and I am not referring to sod or packed dirt.  If 

you need 8:50 or 26 inch tires to keep from digging in then you need the 

little wheel on the back, but I have put my Vixen in most of the Idaho 

back country strips with no concern. The advantage in that it handles 

like a go cart on the ground and will take a lot of cross wind. The tail 

wheel version is easy if you make sure that there is no toe in, that you 

land slow enough, and maybe most importantly if you are landing on 

pavement that your air pressure is down in the mains - 10 to 15 pounds, 

and up towards the limit in the tailwheel. If anyone is interested and 

in my area I have two model 5's in my hangar, with the little wheel on 

different ends that I would be happy to take you flying in each so you 

can see for yourself. However if you are here you are also just a few 

minutes from the factory and John can show you also.

 	  Quote:

kitfoxmike

Joined: 05 Dec 2006
Posts: 373

Posted: Tue Dec 05, 2006 11:30 am Post subject: Re: Conventional Vs Tail and other training

geees,

I think this thread started with a fella wanting a nose wheel airplane, I'm sure because he just doesn't have the skills or want the skills associated with rudder control.  Yes the tail plane is more unstable on the ground, you need rudder skills.  I say lets give the original poster some ideas on the choice between the ch701 vs. kitfox nose wheel airplane not try to convince him that the tail wheel airplane is easy to fly and not a problem.  How do any of us know how this persons skills are or want to be.  I for one will never try to talk anybody into a tail plane.  I have about 600 hrs in my fox, tail wheel, and although I feel it is the funnest most satisfying airplane to fly, I will not advice another person that the tail wheel is the only airplane to fly.  Nor will I tell a nose wheel pilot that in short he is a sissy, and that nose wheel airplanes in short, hasn't been said, should be outlawed.  Lets move on.

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