Tail Wheels & Tail Booms snapp'n

[POPS]

I was warned about the possibility of a glassed on tail wheel possibly being the deciding factor in your tail boon snapping off in a extreme ground loop incident, whereas a skid or wheel that is intended to tear off could be the deciding factor in just the opposite happening.
I've left my steel shoe, glued on rubber skid in place, and my super faired tail wheel I made, off.
Any spinout or repair people care to comment on the idea of the tail boom slamming into the turf at a high rotation speed with a hard mounted TW.

[BobW]

On 11/17/2011 2:02 PM, POPS wrote:
> I was warned about the possibility of a glassed on tail wheel possibly
> being the deciding factor in your tail boon snapping off in a extreme
> ground loop incident, whereas a skid or wheel that is intended to tear
> off could be the deciding factor in just the opposite happening.
> I've left my steel shoe, glued on rubber skid in place, and my super
> faired tail wheel I made, off.
> Any spinout or repair people care to comment on the idea of the tail
> boom slamming into the turf at a high rotation speed with a hard mounted
> TW.
>

Ruh roh! This sort of question is dangerously close to FUDland. (That's
FearUncertaintyDoubtland.) All fans of Absolute Certainty should read no
further!!!

Considered from an energy dissipation perspective, any 'tailwheel mount' that
happens to break away from the fuselage dissipates a finite amount of energy
from what remains in the moving glider, and in that sense reduces the
possibility the next sideways load on the fuselage will have sufficient energy
to break the tailboom. That said, side-load-inducing events are by nature
pretty much uncontrollable (once underway, dry chuckle), dynamic, and
unpredictable...meaning analytical results will always be arguably applicable.

The fact is, absolute answers to the posed question won't be found in reality.

That said, I know of a Zuni (solidly-mounted, fixed tailwheel, albeit by
original design) that has never had a broken tailboom in 2050+ hours. Make of
that what you will, but I'm of the school that believes Joe Pilot can far
better control the *likelihood* of a groundloop through his actions, than he
can the *nature* of any J.P.-induced groundloop.

YMMV
Bob W.

[Dave Nadler]

On Thursday, November 17, 2011 9:31:36 PM UTC-5, BobW wrote:
> ... That said, side-load-inducing events are by nature
> pretty much uncontrollable (once underway, dry chuckle),

Stick forward to lift the tail as a groundloop develops
will always reduce the possibility of the tail digging in
(and tailboom damage).

Remember to get the stick sharply forward next time
you groundloop !

Best Regards, Dave

PS: I wish I had a video of an ASW-22 groundlooping
for the umpteenth time (failure to dump on one side).
The pilot was quite accomplished - lifted the tail
just as the tip hit the ground. No damage but one
humongous cloud of dust...

[gemerson]

This is why it's very important to apply a large quantity of butter or
margarine to the circumference of your tailwheel before each flight.
The butter reduces the side loads and thus prevents the tail boom from
cracking.


On Nov 17, 3:02*pm, POPS > wrote:
> I was warned about the possibility of a glassed on tail wheel possibly
> being *the deciding factor in your tail boon snapping off in a extreme
> ground loop *incident, *whereas a skid or wheel that is intended to tear
> off could be the deciding factor in just the opposite happening.
> I've left my steel shoe, glued on rubber skid in place, and my super
> faired tail wheel I made, off.
> Any spinout or repair people care to comment on the idea of the tail
> boom slamming into the turf at a high rotation speed with a hard mounted
> TW.
>
> --
> POPS

[[email protected]]

On Nov 17, 4:02*pm, POPS > wrote:
> I was warned about the possibility of a glassed on tail wheel possibly
> being *the deciding factor in your tail boon snapping off in a extreme
> ground loop *incident, *whereas a skid or wheel that is intended to tear
> off could be the deciding factor in just the opposite happening.
> I've left my steel shoe, glued on rubber skid in place, and my super
> faired tail wheel I made, off.
> Any spinout or repair people care to comment on the idea of the tail
> boom slamming into the turf at a high rotation speed with a hard mounted
> TW.
>
> --
> POPS

The currently popular large tail wheels do a good job of helping keep
the glider straight which seems to
help avoid the problem in the first place.
Once they are seriously sideways in a true ground loop, they slide
reasonably well.
Once the tail digs in, the boom breaks.
Does a break away skid/tailhweel avoid this? maybe -sometimes.
I've put a number of modern tailwheels in older skid equipped gliders
and every owner has bee happy with the
improvement.
FWIW
UH

[JJ Sinclair[_2_]]

Hmmm,
I have repaired maybe 15 broken booms including 3 that I have cardinal
knowledge of and it is my humble opinion that the tail wheel dragging
sideways has little to do with snapping the boom. In all 3 of my
personal recollections, the tail was off the ground during the event
(2 had wheels, 1 had a skid). I watched a Discus come as close as it
could to breaking its boom when it landed beside me, only a bit deeper
into the barley field at Camby, Ca The left wing tip caught a clump of
barley and around it came, tail off the ground, spun 180, T-tail laid
over a good 30 degrees, then the boom came down and she just sat there
and shook for a moment. What determines weather you break the boom or
not is speed, ground loop below 40 knots and you will probably come
out unscathed, do it above 40 and she's likely to break (Libells
reduce by 10 knots). What's really going on is simply this, The wing
can take it quite well because it has a spar, the boom doesn't and
one side goes into compression while the other is held in tension,
compression looses and buckles inward, do it hard enough (speed) and
she snaps off, tail wheel had very little to do with it.
As always, just my humble opinion,
JJ

[Rex Mayes]

JJ,
If I may add.... The torsional load of the T tail, especially with
lead weight installed is a big factor as well. I do not believe the
style of tail wheel is a factor in tail boom fractures.
The style of landing, on the other hand...:(

Rex

[John[_30_]]

With all that logic and experience talking....can't deny that having
something there that comes unglued under stress (tail skid) is a better
situation than something permanently mounted (tail wheel) that increases the
dragging (sideways) forces. Bare fiberglass slides better.
In my experience, I've had several tail skids come off during off field
landings....did it save my boom? dunno....but, the thing didn't break!!
(Hard to find those things!!!)

What's probably more important is to avoid any weights (batteries,
ballast...etc) placed anywhere up high in the fin that increases the
torsional twisting motion. Mike Adams cautioned me against this when I
bought my first LS-6 from him. I've always put my
balance weights down low back there, using the factory mount at the lower
rudder hinge bolts.....and no tail batteries, ever.

J4

[JJ Sinclair[_2_]]

On Nov 19, 2:24*pm, "John" > wrote:
> With all that logic and experience talking....can't deny that having
> something there that comes unglued under stress (tail skid) is a better
> situation than something permanently mounted (tail wheel) that increases the
> dragging (sideways) forces. * Bare fiberglass slides better.
> In my experience, I've had several tail skids come off during off field
> landings....did it save my boom? *dunno....but, the thing didn't break!!
> (Hard to find those things!!!)
>
> What's probably more important is to avoid any weights (batteries,
> ballast...etc) placed anywhere up high in the fin that increases the
> torsional twisting motion. * * Mike Adams cautioned me against this when I
> bought my first LS-6 from him. * I've always put my
> balance weights down low back there, using the factory mount at the lower
> rudder hinge bolts.....and no tail batteries, ever.
>
> J4

I believe the issue is that pneumatic tail wheel will provide much
more grip on pavement and therefor provide better directional control.
On grass or gravel, either work about the same. In a cross wind
landing ,the only way to keep her pointed down the runway is to hold
back stick which gives the pneumatic wheel max grip. In the Genesis I
force the nose wheel down with full forward stick in order to give it
max grip, but even then when my speed equals the wind speed, she
weather-vanes into the wind. Then I must lower the opposite wing and
the little tip wheel gives enough drag to keep her doing my bidding.
Landing a flying wing in a cross-wind has been an educational
experience, but I have once landed with a 30 knot direct cross-wind
and walked away unscathed!.
Cheers,
JJ

[Dave Nadler]

Guys - Tail up prevents catching on rough ground
and reduces side-load on tailboom if in crops.
Tail up if you start to groundloop !
See ya, Dave

[[email protected]]

On Nov 20, 5:32*pm, Dave Nadler > wrote:
> Guys - Tail up prevents catching on rough ground
> and reduces side-load on tailboom if in crops.
> Tail up if you start to groundloop !
> See ya, Dave

I have to disagree here as far as suggesting some technique thet is
planned.
Tail up almost ensures a ground loop.
Tail down reduces the likelyhood of a groundloop substantially.
Very few ground loops occur as a planned event(the "I'm running out of
field" event). The strong majority are surprises caused by catch a
wing.
I most cases, the lower energy in the event that come from a slow held
off landing significantly reduces the likelyhood of a fuselage
breaking event.
If you lose it, you don't have much time to try to raise the tail.
Just squeeze the brake hard and hope for the best.
Another opinion FWIW.
UH

[Dave Nadler]

Sorry if I wasn't clear:
Tail up AFTER ground-loop starts or is inevitable,
not first. There's plenty of time to respond.
This is *after* a fully held off tail-first landing.
Seen it done multiple times ;-)
Do wish I had a video of the 22 going around.

PS: Most of these guys have Tost brakes so
squeezing won't do anything...

[Karl Striedieck[_2_]]

On Nov 21, 6:14*pm, Dave Nadler > wrote:
> Sorry if I wasn't clear:
> Tail up AFTER ground-loop starts or is inevitable,
> not first. There's plenty of time to respond.
> This is *after* a fully held off tail-first landing.
> Seen it done multiple times ;-)
> Do wish I had a video of the 22 going around.
>
> PS: Most of these guys have Tost brakes so
> squeezing won't do anything...

The most important reason for forward stick in a ground loop is not to
save the tail boom, as it will come crashing down at the termination
of the event anyway. Keeping the nose buried helps prevent an inverted
wingover as the wing accelerating forward develops enough lift to turn
the ship upside down. This can be fatal and almost was to Joe Conn at
Chester, SC in his ASW-17 many years ago.

And, further to the subject, all pilots should know how to execute an
intentional ground loop should they be faced with the need (fence,
road, embankment, etc.) Stick full forward, wing down, full rudder in
direction of down wing. This is part of German gliding instruction.
Should be here as well.