Some tailwheel questions/comments

Not really, and I'd be surprised if you could taxi a Citabria with the
tailwheel raised anyway. Easy in a cub, though.


Firstly this isnt a troll and if somebody feels it is, they simply
need to ignore it, thats how usenet works. Anyways, the question was
based more on what I saw on the takeoff run where we raise the tail as
airspeed increases. It just felt more stable and more like a
conventional gear takeoff run in that phase, so I was just wondering.
The intent of the question wasn't about how to taxi at a high speed.

The problem with the Citabria is it's a bit too easy for tailwheel
conversion. You'll get the basics, but if you try a cub afterwards you'll
find it significantly more difficult, wheras the other way around would be
a piece of cake. Citabria is a good airplane, but it's not the best
tailwheel trainer for that reason. However, it will certainly do in a
pinch!

Thanks for the tip, I have been looking to find a place to learn in a
cub but the closest one is about 70 miles away, so that may have to
wait.

The CG doesn't change significantly when the tail is raised, though, to
answer your question, and fast taxiing is something best left to someone
with a LOT of tailwhel time. Taxiing on the mains is something best left to
airshow pilots or guys that can afford to replace props as easily as they
would buy a cup of coffee.

What my instructor seemed to imply (and things didn't really sink in
till about a day after the flying) was that the takeoff roll is more
stable when the tail is up. So I was wondering if the CG shifts
forward when the tail is raised because this is a more stable
configuration than when the CG is behind the main wheels.

wrote in
ups.com:



Not really, and I'd be surprised if you could taxi a Citabria with
the tailwheel raised anyway. Easy in a cub, though.


Firstly this isnt a troll and if somebody feels it is, they simply
need to ignore it, thats how usenet works. Anyways, the question was
based more on what I saw on the takeoff run where we raise the tail as
airspeed increases. It just felt more stable and more like a
conventional gear takeoff run in that phase, so I was just wondering.
The intent of the question wasn't about how to taxi at a high speed.

Ah, OK. Wel, the main reason you get the tail up is to aid acceleration
and to have th eairplane in the correct atttude when you rotate.
You have a lot of power on and that is why the airplane feels more
stable than when you are taxiing. The reason being the vast amount of
air yu have going over the rudder.
Not all airplanes re like that, BTW. Some get very interesting when you
raise the tail on takeoff!

The problem with the Citabria is it's a bit too easy for tailwheel
conversion. You'll get the basics, but if you try a cub afterwards
you'll find it significantly more difficult, wheras the other way
around would be a piece of cake. Citabria is a good airplane, but
it's not the best tailwheel trainer for that reason. However, it will
certainly do in a pinch!

Thanks for the tip, I have been looking to find a place to learn in a
cub but the closest one is about 70 miles away, so that may have to
wait.

Nothing wrong with a Citabria, but the cub is just so perfect. You'll
learn a lot in a Citabira as well, Just be aware that when you get the
tailwheel signoff you're not "there" In fact it doesn't matter what
you've been checked out in, you're only just like a kid who's been let
go onhis first two wheeler..

The CG doesn't change significantly when the tail is raised, though,
to
answer your question, and fast taxiing is something best left to
someone with a LOT of tailwhel time. Taxiing on the mains is
something best left to airshow pilots or guys that can afford to
replace props as easily as they would buy a cup of coffee.

What my instructor seemed to imply (and things didn't really sink in
till about a day after the flying) was that the takeoff roll is more
stable when the tail is up. So I was wondering if the CG shifts
forward when the tail is raised because this is a more stable
configuration than when the CG is behind the main wheels.


Ah, OK. Well, it might have something to do with that, but I'd suspect
it;s more to do with decreasing the angle of attack on the wings.


Bertie

On Tue, 25 Sep 2007 10:39:37 -0700, wrote:

What my instructor seemed to imply (and things didn't really sink in
till about a day after the flying) was that the takeoff roll is more
stable when the tail is up. So I was wondering if the CG shifts
forward when the tail is raised because this is a more stable
configuration than when the CG is behind the main wheels.

It's still aft of the mains!

I get the tailwheel off the ground as soon as the Cub begins to roll.
You don't want to do a takeoff roll flat on the asphalt, though, or
even on the grass. The plane will pound. Have the tail enough below
parallel that some of the weight of the plane is carried by the wings.

(I never really thought about this before, so excuse me if the wording
is awkward.)


Blue skies! -- Dan Ford

Claire Chennault and His American Volunteers, 1941-1942
new from HarperCollins www.FlyingTigersBook.com

On Sep 25, 12:39 pm, wrote:
Not really, and I'd be surprised if you could taxi a Citabria with the
tailwheel raised anyway. Easy in a cub, though.

Firstly this isnt a troll and if somebody feels it is, they simply
need to ignore it, thats how usenet works. Anyways, the question was
based more on what I saw on the takeoff run where we raise the tail as
airspeed increases. It just felt more stable and more like a
conventional gear takeoff run in that phase, so I was just wondering.
The intent of the question wasn't about how to taxi at a high speed.

The problem with the Citabria is it's a bit too easy for tailwheel
conversion. You'll get the basics, but if you try a cub afterwards you'll
find it significantly more difficult, wheras the other way around would be
a piece of cake. Citabria is a good airplane, but it's not the best
tailwheel trainer for that reason. However, it will certainly do in a
pinch!

Thanks for the tip, I have been looking to find a place to learn in a
cub but the closest one is about 70 miles away, so that may have to
wait.

The CG doesn't change significantly when the tail is raised, though, to
answer your question, and fast taxiing is something best left to someone
with a LOT of tailwhel time. Taxiing on the mains is something best left to
airshow pilots or guys that can afford to replace props as easily as they
would buy a cup of coffee.

What my instructor seemed to imply (and things didn't really sink in
till about a day after the flying) was that the takeoff roll is more
stable when the tail is up. So I was wondering if the CG shifts
forward when the tail is raised because this is a more stable
configuration than when the CG is behind the main wheels.

OK, I'm just a student pilot, and not a taildragger student either.
But I know a little physics. The CG is still behind the mains even
with the tail up. It is possible that the airplane would feel more
stable in yaw when it is accelerating, however. Since the center of
gravity is being pulled along behind the propeller, I would think the
airplane would tend to stay in line. This ignores other influences
like crosswinds and the torque effects of the prop which would tend to
counter this. And it won't help you in taxiing when you are moving at
a constant speed.

OK, I'm just a student pilot, and not a taildragger student either.
But I know a little physics. The CG is still behind the mains even
with the tail up. It is possible that the airplane would feel more
stable in yaw when it is accelerating, however. Since the center of
gravity is being pulled along behind the propeller, I would think the
airplane would tend to stay in line. This ignores other influences
like crosswinds and the torque effects of the prop which would tend to
counter this. And it won't help you in taxiing when you are moving at
a constant speed.

Yes, you are right about the CG not changing, I was probably
mistakenly thinking that the CG moves forward relative to the ground
as the airplane nose is "lowered" but I think that's not correct. The
stability in a level attitude while taxing probably also comes from
the fact that the P-factor is gone and there is no turning tendency
any more.

On Sep 25, 11:37 pm, wrote:
OK, I'm just a student pilot, and not a taildragger student either.
But I know a little physics. The CG is still behind the mains even
with the tail up. It is possible that the airplane would feel more
stable in yaw when it is accelerating, however. Since the center of
gravity is being pulled along behind the propeller, I would think the
airplane would tend to stay in line. This ignores other influences
like crosswinds and the torque effects of the prop which would tend to
counter this. And it won't help you in taxiing when you are moving at
a constant speed.

Yes, you are right about the CG not changing, I was probably
mistakenly thinking that the CG moves forward relative to the ground
as the airplane nose is "lowered" but I think that's not correct. The
stability in a level attitude while taxing probably also comes from
the fact that the P-factor is gone and there is no turning tendency
any more.

Thrust acts along the centerline whether the airplane is
tracking straight or not, whether the CG is behind the mains or in
front. The only time thrust is a little off is when the AOA is high
(tail low) and the downgoing blade has more pull (P-factor). The
airplane will still want to pull left with the tail up due to the
swirl of the prop slipstream striking the left side of the fin, and a
small amount caused by more pressure on the left main due to engine
torque reaction. Raising the tail will make the nose swerve left, a
gyroscopic precession caused by the prop's rotating mass.
Whatever the airplane tries to do, you have to be ready for it
and not afraid to use ALL the controls rather aggressively to show it
who's boss. It won't fly itself.

Dan