Improved Towhook from Aircraft Spruce

North America: Anyone have experience with this new, improved tow
hook based upon the Schweizer hook? Your FAA Approval process?

From the catalog at www.aircraftspruce.com (see photos there)

Aircraft Spruce Pilot Supplies - Towing Equipment
GLIDER & BANNER TOW HOOKS

These tow hooks are available in two models. One is a bolt-on tow hook
with a mounting lug which is ideal for attachment to a tail tie down
point. The other model is a weld-on tow hook designed to be directly
welded to a custom mounting bracket.

These two hooks are similar in design to the Schweizer manufactured
two hooks that are no longer available. Design improvements were made
to increase emergency release capability at all towing loads and
angles.

These new tow hooks have greater release arm leverage and a unique
hardened roller release design to reduce release force at all tow
angles. Additionally, the geometry of the tow hook housing was
improved to keep the tow ring in the optimum position to minimize
release force.

FAA approval can be obtained for the complete tow hook and release
system by following the guidelines in FAA Advisory Circular 43.13-2A,
Chapter 8, titled, "Glider and Banner Tow-Hitch Installations" and the
included tow hook installation instruction.

Description Part No. Price
GLIDER TOW HOOK (WELD ON) 13-04974 $302.81
GLIDER TOW HOOK (BOLT ON) 13-04975 $340.40

On Nov 22, 6:24 am, Burt Compton - Marfa wrote:
North America: Anyone have experience with this new, improved tow
hook based upon the Schweizer hook? Your FAA Approval process?

No experience with this release but I've noticed that some hook
installations don't release until most of the release handle motion
range is used up. Since this release has a longer arm then more
release handle motion will be required. I wonder if that will require
a redesigned release handle or perhaps just more careful attention to
cable adjustment.

Andy

The roller is a huge designe improvement too, both for setting the
latch and pushing open.

Would like to see a heavier guage of material on the sides. The
Schweizer hooks WILL bend and/or jam with the just the right angle of
side load.


Michael

Andy wrote:
On Nov 22, 6:24 am, Burt Compton - Marfa wrote:
North America: Anyone have experience with this new, improved tow
hook based upon the Schweizer hook? Your FAA Approval process?

No experience with this release but I've noticed that some hook
installations don't release until most of the release handle motion
range is used up. Since this release has a longer arm then more
release handle motion will be required. I wonder if that will require
a redesigned release handle or perhaps just more careful attention to
cable adjustment.

Andy

They should be compared to that which really works--a Tost release. If they
are not better than a Tost, it doesn't matter if they are better than the
old Schweizer hook.
my 0.02USD
--
Hartley Falbaum
"KF" USA

"Burt Compton - Marfa" wrote in message
...
North America: Anyone have experience with this new, improved tow
hook based upon the Schweizer hook? Your FAA Approval process?

From the catalog at www.aircraftspruce.com (see photos there)

Aircraft Spruce Pilot Supplies - Towing Equipment
GLIDER & BANNER TOW HOOKS

These tow hooks are available in two models. One is a bolt-on tow hook
with a mounting lug which is ideal for attachment to a tail tie down
point. The other model is a weld-on tow hook designed to be directly
welded to a custom mounting bracket.

These two hooks are similar in design to the Schweizer manufactured
two hooks that are no longer available. Design improvements were made
to increase emergency release capability at all towing loads and
angles.

These new tow hooks have greater release arm leverage and a unique
hardened roller release design to reduce release force at all tow
angles. Additionally, the geometry of the tow hook housing was
improved to keep the tow ring in the optimum position to minimize
release force.

FAA approval can be obtained for the complete tow hook and release
system by following the guidelines in FAA Advisory Circular 43.13-2A,
Chapter 8, titled, "Glider and Banner Tow-Hitch Installations" and the
included tow hook installation instruction.

Description Part No. Price
GLIDER TOW HOOK (WELD ON) 13-04974 $302.81
GLIDER TOW HOOK (BOLT ON) 13-04975 $340.40

Andy wrote:

No experience with this release but I've noticed that some hook
installations don't release until most of the release handle motion
range is used up. Since this release has a longer arm then more
release handle motion will be required. I wonder if that will require
a redesigned release handle or perhaps just more careful attention to
cable adjustment.

I've always liked the Scheder-design HP nose or chin hooks. They seem
simple in design and as far as I know are quite robust. The neat thing
is upon release they completely retract into the fuse and cover the
opening with a flush plate.

I would guess that Bob K. of HP Aircraft owns the rights to the design.
I'm surprised that I don't see this hook retrofitted to a lot of other
glider types.

Regards,

-Doug

"Doug Hoffman" no.spam wrote in message
.. .

I've always liked the Scheder-design HP nose or chin hooks. They seem
simple in design and as far as I know are quite robust. The neat thing is
upon release they completely retract into the fuse and cover the opening
with a flush plate.

I would guess that Bob K. of HP Aircraft owns the rights to the design.
I'm surprised that I don't see this hook retrofitted to a lot of other
glider types.


Doug,

The 1-35A, SparrowHawk and, I believe, Zuni have tow hooks simular the Dick
Schreder's HP/RS series design.

Wayne
HP-14 "6F"
http://www.soaridaho.com/Schreder

I believe the hook described in thr Aircraft Spruce catalogue is for the
Towplane. The problem is release ability under extreme vertical or
horizontal (side) loads by a very out-of-position glider. This is of great
interest to towpilots.

--
Hartley Falbaum


"Wayne Paul" wrote in message
...

"Doug Hoffman" no.spam wrote in message
.. .

I've always liked the Scheder-design HP nose or chin hooks. They seem
simple in design and as far as I know are quite robust. The neat thing
is upon release they completely retract into the fuse and cover the
opening with a flush plate.

I would guess that Bob K. of HP Aircraft owns the rights to the design.
I'm surprised that I don't see this hook retrofitted to a lot of other
glider types.


Doug,

The 1-35A, SparrowHawk and, I believe, Zuni have tow hooks simular the
Dick Schreder's HP/RS series design.

Wayne
HP-14 "6F"
http://www.soaridaho.com/Schreder

Long time readers of this news group will remeber posting from me on
the subject of Tost tow hooks verses all the others. My opinion is
tilll the same, nothing compairs to a Tost tow hook either on the
glider or on the tow plane, for safety and reliability. As mentioned
in other replys to this subject the other tow hooks have have an
increase in the force needed to actuate the release that is portional
to the tension on the tow line. This is not good. None of the other
tow hooks have a schedule of maintaince, none of the others lock over
center and hold the tow ring in a position for easy and clean release
of the tow rope. The Schweizer and Schreader style hooks just can not
compaire to a Tost.

One reason you do not see these other tow releases retrofitted to a
lot of other gliders is that except for the Schweizer gliders, they
are not legal to use in Type Certificated gliders. For a Type
Certificated glider that was originally fitted with a Tost hook, to
have the other sype hook installed would require a fair ammount of
paperwork. A knowlegable FAA inspector would not accept only a form
337 for this change.

The Tost is so good that it has been copired by Ottfur in England and
by SZD and other former East Block glider manufactuers.

Yes, they are more expensive, but I think you really do get what you
pay for, and I think that considering the tow release's critical part
in safe launching, the extra cost is a small price to pay.

Robert Mudd
Moriarty, New Mexico
Expirencing our first snow fall of the season today.

I've always liked the Scheder-design HP nose or chin hooks. �They seem
simple in design and as far as I know are quite robust. �The neat thing
is upon release they completely retract into the fuse and cover the
opening with a flush plate.

I would guess that Bob K. of HP Aircraft owns the rights to the design.
� I'm surprised that I don't see this hook retrofitted to a lot of other
glider types.

Regards,

-Doug

Robert Mudd is dead on.

I would add that there is considerable safety and operational value in
standardization. On any airfield today, Tost is the dominant
ringset/release system. If a second system is used, it adds ring switching
to the rope handling chore. There is always a temptation to use a Tost
ringset on a Schweizer which WILL occasionally jam the release.
Standardizing on Tost is expensive but safer and more convenient.

Bill D


wrote in message
...
Long time readers of this news group will remeber posting from me on
the subject of Tost tow hooks verses all the others. My opinion is
tilll the same, nothing compairs to a Tost tow hook either on the
glider or on the tow plane, for safety and reliability. As mentioned
in other replys to this subject the other tow hooks have have an
increase in the force needed to actuate the release that is portional
to the tension on the tow line. This is not good. None of the other
tow hooks have a schedule of maintaince, none of the others lock over
center and hold the tow ring in a position for easy and clean release
of the tow rope. The Schweizer and Schreader style hooks just can not
compaire to a Tost.

One reason you do not see these other tow releases retrofitted to a
lot of other gliders is that except for the Schweizer gliders, they
are not legal to use in Type Certificated gliders. For a Type
Certificated glider that was originally fitted with a Tost hook, to
have the other sype hook installed would require a fair ammount of
paperwork. A knowlegable FAA inspector would not accept only a form
337 for this change.

The Tost is so good that it has been copired by Ottfur in England and
by SZD and other former East Block glider manufactuers.

Yes, they are more expensive, but I think you really do get what you
pay for, and I think that considering the tow release's critical part
in safe launching, the extra cost is a small price to pay.

Robert Mudd
Moriarty, New Mexico
Expirencing our first snow fall of the season today.

I've always liked the Scheder-design HP nose or chin hooks. ?They seem
simple in design and as far as I know are quite robust. ?The neat thing
is upon release they completely retract into the fuse and cover the
opening with a flush plate.

I would guess that Bob K. of HP Aircraft owns the rights to the design.
? I'm surprised that I don't see this hook retrofitted to a lot of other
glider types.

Regards,

-Doug

wrote:
Long time readers of this news group will remeber posting from me on
the subject of Tost tow hooks verses all the others. My opinion is
tilll the same, nothing compairs to a Tost tow hook either on the
glider or on the tow plane, for safety and reliability.

Hi Robert,

Actually I did do a search of the message archives before posting and
didn't see anything about problems with a Schreder tow hook. Yes, I saw
your comments, but they were directed at the Schweizer hook.


As mentioned
in other replys to this subject the other tow hooks have have an
increase in the force needed to actuate the release that is portional
to the tension on the tow line.

Interesting. I have flown several different Schreder gliders and never
had a problem with that.


This is not good. None of the other
tow hooks have a schedule of maintaince, none of the others lock over
center and hold the tow ring in a position for easy and clean release
of the tow rope. The Schweizer and Schreader style hooks just can not
compaire to a Tost.

What are the failure modes of the Schreder nose hook (not the Schweizer
or Applebay hook)? How does the failure rate of the Schreder hook
compare to the Tost hook? I think there are quite a few Schreder pilots
out there now who would be keenly interested in knowing about this.



One reason you do not see these other tow releases retrofitted to a
lot of other gliders is that except for the Schweizer gliders, they
are not legal to use in Type Certificated gliders. For a Type
Certificated glider that was originally fitted with a Tost hook, to
have the other sype hook installed would require a fair ammount of
paperwork. A knowlegable FAA inspector would not accept only a form
337 for this change.

Of course. Sorry if you thought I meant otherwise.

Regards,

-Doug