Today's Message Index:
----------------------
1. 05:43 AM - carb (Oscar Zuniga)
2. 07:00 AM - Wing root rib (Egan, John)
3. 08:55 AM - Re: Kevlar Drag Wires (Tom Bernie)
4. 09:36 AM - Re: carb (Gary Gower)
5. 10:16 AM - Re: carb (Barry Davis)
Message 1
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--> Pietenpol-List message posted by: "Oscar Zuniga" <taildrags@hotmail.com>
>I dont know if there are this type of spring shops in USA
No, Gary... so I'd better go down to Guadalajara to get a spring ;o)
Oscar Zuniga
San Antonio, TX
mailto: taildrags@hotmail.com
website at http://www.flysquirrel.net
Message 2
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Hello all,
I believe I am 99% finished with the wing construction as I have the
entire wing and ailerons assembled, glued, and sanded, with the
exception of the wing root rib installation. Over the weekend, I dry
=66it the plywood pieces and the flat steel strap wing brackets on the
root ends of the spars. I have the spars, plywood and fittings drilled
and loosely bolted but not glued. I will need to add a final rib near
the end of the spars and I have been hesitating on this. My question
is:
Does the end rib get the vertical member cut away where it would overlap
the flat steel wing bracket=3F When I made the rib, I offset the vertical
member the same thickness as the plywood with the intent to cut away the
area for the steel strap. A person could also build that first rib with
a solid sheet of plywood on the outside to have a nice flat surface to
glue the fabric to. I'm sure there are many good solutions, and I am
interested to hear some other options. After I get this last rib on, I
can then add varnish.
Thanks,
John
Greenville, Wi.
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Message 3
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| Subject: | Kevlar Drag Wires |
--> Pietenpol-List message posted by: "Tom Bernie" <tsbernie@earthlink.net>
Hans,
I got the following reply from Phillystran --
"There are 2 versions of the 2100 product:
The original version is the HPTG 2100 made from parallel Kevlar 49 yarn
with en extruded PE jacket. The modulus for that item would be
17.5x10E6 psi (conditioned rope value).
In 1990 a second generation product was introduced known as HPTG2100I.
Also made from the Kevlar 49 but a stranded resin impregnated rope with
extruded PU jacket. Modulus is 15.0x10E6 psi.
The HPTG-I version is an inventoried item whereas the HPTG is made to
order with a 5K min.
Kenneth Knight
PHILLYSTRAN, INC.
Manager, Industrial Sales
215-368-6611 *107
fax: 215-362-7956
cell: 267-614-5623
kknight@phillystran.com"
Is 15.0x10E6 psi a useful value in determining the cable usefulness?
Regards,
Tom Bernie
-----Original Message-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Hans
Vander Voort
Sent: Friday, June 02, 2006 4:19 PM
Subject: Re: Pietenpol-List: Kevlar Drag Wires
--> Pietenpol-List message posted by: Hans Vander Voort
<hans.vander.voort@alfalaval.com>
Tom,
I googled the elasticity modulus
Kevlar 49 has a elasticity modulus of 120 Gpa
Carbon Steel has a elasticity modulus of 210 Gpa
The higher the number the lower the elasticity.
Kevlar has a higher fatigue life than steel, due to being more elastic.
Probably Kevlar would be more suited as use in bracing wires, where
there
is a lot of vibration, or control cables where there is a lot of
bending.
Inside the wing with no turbulence and no bending I would not use it,
the
additional stretching might exceed the limits of the wood structure.
Then again the certified aircraft builders Boeing and Airbus seem to use
Kevlar in secondary structures, why not in primary ?
Hans
Tom Bernie
<tsbernie@earthli
nk.net>
To
Sent by: pietenpol-list@matronics.com
owner-pietenpol-l
cc
ist-server@matron
ics.com
Subject
Re: Pietenpol-List: Kevlar Drag
Wires
06/02/2006 02:38
PM
Please respond to
pietenpol-list@ma
tronics.com
--> Pietenpol-List message posted by: Tom Bernie
<tsbernie@earthlink.net>
Hans,
The tower instructions call for tensioning to 15% breaking strength then
under that load it relaxes to 10% over a period of 30 days. Tower
builders
seem to consider it equivalent to galvanized. I'm trying to get
elasticity
or dymanic stretching data. It weighs nothing and at .22" dia and 2100#
breaking strength, it costs $.59 @ foot.
Regards,
Tom Bernie
-----Original Message-----
>From: Hans Vander Voort <hans.vander.voort@alfalaval.com>
>Sent: Jun 2, 2006 1:55 PM
>To: pietenpol-list@matronics.com
>Cc: owner-pietenpol-list-server@matronics.com,
pietenpol-list@matronics.com
>Subject: Re: Pietenpol-List: Kevlar Drag Wires
>
>--> Pietenpol-List message posted by: Hans Vander Voort
<hans.vander.voort@alfalaval.com>
>
>Too elastic ?
>
>Hans
>
>
> "Tom Bernie"
> <tsbernie@earthli
> nk.net>
To
> Sent by: <pietenpol-list@matronics.com>
> owner-pietenpol-l
cc
> ist-server@matron
> ics.com
Subject
> Pietenpol-List: Kevlar Drag
Wires
>
> 06/02/2006 11:22
> AM
>
>
> Please respond to
> pietenpol-list@ma
> tronics.com
>
>
>
>
>Folks,
>
>
>Anybody have any thoughts about the advisability of using Kevlar cable
>(Phillystran) for Drag/Anti Drag wires? On the surface, the physical
>properties look great.
>
>
>Thanks,
>
>
>Tom Bernie
>
>
Message 4
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Sure, Welcome! Any time will be great.
Also if you like, I can get you a couple and send them to you. Just need to
get a feeling of the spring this next Saturday at the Club, The spring shop is
about 5 blocks from my factory, so no big deal to get it.
There they made the spring that we used for towing in my hang gliding days, (20
years ago) also the springs for my Ladder Pou landing gear and lots of others.
Just go there and tell them how much force needed and how much the travel of
the spring. two or 3 days later is ready.
Saludos
Gary Gower.
Oscar Zuniga <taildrags@hotmail.com> wrote:
--> Pietenpol-List message posted by: "Oscar Zuniga"
>I dont know if there are this type of spring shops in USA
No, Gary... so I'd better go down to Guadalajara to get a spring ;o)
Oscar Zuniga
San Antonio, TX
mailto: taildrags@hotmail.com
website at http://www.flysquirrel.net
__________________________________________________
Message 5
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I know quiet a few pilots that have the "spring" on their carbs. I
thought about it and came up with a few observations.
I think the cable would probably break when you PULL the throttle to
closed and put tension on the cable. I don't think it would make sense
for a cable to break by PUSHING it through the jacket. If it broke
inside the jacket, it seems that it would still push through, but might
be harder than normal due to frayed ends. This would leave the throttle
on Open.
If the cable came off the carb lever by breakage or the bolt wearing
thru or falling out, then adding a very soft spring would be the best
idea in the world and you would be patting yourself on the back for a
long time after landing successfully.
If the spring is heavy, you will experience throttle creep and will
be constantly adjusting the throttle, it also puts a constant strain on
the cable. Look at the hardware stores or on the internet and look for a
spring with at least 1/2" diameter and very soft and pulls very easily.
If the ends are not long enough, an extender can be made from med to
heavy safety tie wire and anchored somewhere on the engine, not to the
motor mount to isolate constant vibration.
My 172 has one, but the 150 that I own with a partner does not. Go
figure. Our Piets are not flying yet. We just replaced the cable on the
150 and it had several thousand hours on it. It was not having a
problem, but replacement seemed like cheap insurance, especially if our
kids take it out for a spin.
If you ever feel a binding in the throttle, even just once, it is
time to take a look at that cable. By being a stranded cable, usually
one or two strands will break first and cause some friction. Consider
this your fair warning.
You need to have in mind a plan to cope with this type of emergency.
Either turn the engine switch on and off and blow the ends out of the
mufflers or get into a safe position at the airport, shut the engine
down and do a dead stick landing. Barry
----- Original Message -----
From: Dick Navratil
To: pietenpol-list@matronics.com
Sent: Sunday, June 04, 2006 12:03 AM
Subject: Pietenpol-List: carb
Has anyone installed a spring on the Stromberg carb to bring it to
full open in case of a linkage failure in flight? I went out flying
today, using a runway with no good emergency landing spots on the
departure end. Sitting around the hangar chatting later, that subject
came up and it sounded like a good idea.
Dick N.
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