SZD-36 Cobra 15

[[email protected]]

A friend is considering purchasing a SZD-36 Cobra 15 glider. Comments
from anyone having owned or flown this model aircraft would be
appreciated.

Terry/DG800B

[Paul Remde]

Hi Terry,

I think that it is the type owned by Matthew Sawhill in Ankeny, Iowa. He
would be a good reference. ... Or is it his glider that is for sale? Did
he move up to something else?

Paul Remde

> wrote in message
...
>A friend is considering purchasing a SZD-36 Cobra 15 glider. Comments
> from anyone having owned or flown this model aircraft would be
> appreciated.
>
> Terry/DG800B

[Geoff Vincent]

Hi Terry,

You could try Scott Penrose of Gliding Club of Victoria (Australia)
email . He has owned and flown a Cobra 15 (VH-GJS)
for a couple of years.

Regards,

Geoff Vincent
Grampians Soaring Club

On Sat, 26 Jul 2008 02:14:20 GMT, "Paul Remde" > wrote:

>Hi Terry,
>
>I think that it is the type owned by Matthew Sawhill in Ankeny, Iowa. He
>would be a good reference. ... Or is it his glider that is for sale? Did
>he move up to something else?
>
>Paul Remde
>
> wrote in message
...
>>A friend is considering purchasing a SZD-36 Cobra 15 glider. Comments
>> from anyone having owned or flown this model aircraft would be
>> appreciated.
>>
>> Terry/DG800B
>

[[email protected]]

On Jul 25, 9:14 pm, "Paul Remde" > wrote:
> Hi Terry,
>
> I think that it is the type owned by Matthew Sawhill in Ankeny, Iowa. He
> would be a good reference. ... Or is it his glider that is for sale? Did
> he move up to something else?
>
> Paul Remde
>
> > wrote in message
>
> ...
>
> >A friend is considering purchasing a SZD-36 Cobra 15 glider. Comments
> > from anyone having owned or flown this model aircraft would be
> > appreciated.
>
> > Terry/DG800B

Sawhill flies a Foka 4.

[GK[_1_]]

On Jul 25, 10:01*pm, " <terry-
> wrote:
> A friend is considering purchasing a SZD-36 Cobra 15 glider. Comments
> from anyone having owned or flown this model aircraft would be
> appreciated.
>
> Terry/DG800B

Please make sure that you have the translated copy of Polish
Maintenance Manual from SZD!
It is a beautiful wooden glider however as with any construction it
requires preventative maintenance. There has been an accident in
Alabama where a roman screw retracted from the lower spar (due to a
wear of supporting bushing) and wings collapsed during a high speed
pass. Maintenance manual calls for periodical replacement of those
parts and such a glider would not have been airworthy in Poland.

Regards

GK

[Martin Gregorie[_3_]]

On Sat, 26 Jul 2008 07:17:44 -0700, GK wrote:

> There has been an accident in
> Alabama where a roman screw retracted from the lower spar (due to a
> wear of supporting bushing) and wings collapsed during a high speed
> pass.
>
What is a roman screw?
Is it the same type of wing fixing that the SHK used?

I've not seen the term before and a web search failed to find a suitable
definition.


--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot

[GK[_1_]]

On Jul 26, 2:45*pm, Martin Gregorie
> wrote:
> On Sat, 26 Jul 2008 07:17:44 -0700, GK wrote:
> > There has been an accident in
> > Alabama where a roman screw retracted from the lower spar (due to a
> > wear of supporting bushing) and wings collapsed during a high speed
> > pass.
>
> What is a roman screw?
> Is it the same type of wing fixing that the SHK used?
>
> I've not seen the term before and a web search failed to find a suitable
> definition.
>
> --
> martin@ * | Martin Gregorie
> gregorie. |
> org * * * | Zappa fan & glider pilot

- http://pl.wikipedia.org/wiki/%C5%9Aruba_rzymska

[Tim Taylor]

On Jul 26, 2:19 pm, GK > wrote:
> On Jul 26, 2:45 pm, Martin Gregorie
>
>
>
> > wrote:
> > On Sat, 26 Jul 2008 07:17:44 -0700, GK wrote:
> > > There has been an accident in
> > > Alabama where a roman screw retracted from the lower spar (due to a
> > > wear of supporting bushing) and wings collapsed during a high speed
> > > pass.
>
> > What is a roman screw?
> > Is it the same type of wing fixing that the SHK used?
>
> > I've not seen the term before and a web search failed to find a suitable
> > definition.
>
> > --
> > martin@ | Martin Gregorie
> > gregorie. |
> > org | Zappa fan & glider pilot
>
> -http://pl.wikipedia.org/wiki/%C5%9Aruba_rzymska

In the USA it would be called a Turnbuckle.

[Martin Gregorie[_3_]]

On Sat, 26 Jul 2008 15:07:12 -0700, Tim Taylor wrote:

> On Jul 26, 2:19 pm, GK > wrote:
>> On Jul 26, 2:45 pm, Martin Gregorie
>>
>>
>>
>> > wrote:
>> > On Sat, 26 Jul 2008 07:17:44 -0700, GK wrote:
>> > > There has been an accident in
>> > > Alabama where a roman screw retracted from the lower spar (due to a
>> > > wear of supporting bushing) and wings collapsed during a high speed
>> > > pass.
>>
>> > What is a roman screw?
>> > Is it the same type of wing fixing that the SHK used?
>>
>> > I've not seen the term before and a web search failed to find a suitable
>> > definition.
>>
>> > --
>> > martin@ | Martin Gregorie
>> > gregorie. |
>> > org | Zappa fan & glider pilot
>>
>> -http://pl.wikipedia.org/wiki/%C5%9Aruba_rzymska
>
> In the USA it would be called a Turnbuckle.

Same here, but how, exactly, does that attach the wings? I can understand
that it might pull them together and onto the fuselage pickup pins, but
what locks the spars together?

Martin Simon's 3-view of the Cobra shows the spars apparently meeting at
the fuselage centre line and some sort of circular hatch above their
meeting point: that's why I asked if the Cobra used a similar mechanism to
the SHK.


--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot

[[email protected]]

I think there is a misunderstanding. There are two main screws at the
spar but non of the similar to the linked element.

On of them is vertical and similar to the IS28B2 main pin mechanism.
This attach and secure the two wings. It's unlikely to have failure
here.

Second one is horizontal behind the pilots head. This mechanism adjust
the wings horizontal play. This has to be fastened and secured after
assembly. One of my friend took off without this step... I can imagine
that high stress together with this mistake can be deadly.

Cobra is a robust plane, designed for aerobatics. Because of this
purpose wings are really heavy. Flight characteristics are friendly,
no bad habit like at stdCirrus (all moving tail). Performance is
around dry stdCirrus, stdJantar.

Wheel retraction system is a tricky rotating mechanism, careful
maintenance is needed for proper operation.

Instrument panel is small, limited space for instruments.

Baggage compartment is big, XC equipment can fit easily.

Not all Cobra is fired with CG hook! Winch launch with nose hook is
much lower.

It's a wooden plane with some composite material. Surface waveness can
change a lot by temperature, humidity. So don't worry if your nice
Cobra looks ugly one day, it will be nice again after a while;)

Conenction mechanism below the control stick is a bit weak. It's a
screw adjusted conical system and as dusk usually get's into that
place regular adjustment is needed. Usually this adjustment is a
tricky balancing between low control forces and small play.

If you are interested about some pictures here is my Cobra page:

http://bauerj.fw.hu/Cobra15/

[Frank Whiteley]

On Jul 27, 12:46*pm, wrote:
> I think there is a misunderstanding. There are two main screws at the
> spar but non of the similar to the linked element.
>
> On of them is vertical and similar to the IS28B2 main pin mechanism.
> This attach and secure the two wings. It's unlikely to have failure
> here.
>
> Second one is horizontal behind the pilots head. This mechanism adjust
> the wings horizontal play. This has to be fastened and secured after
> assembly. One of my friend took off without this step... I can imagine
> that high stress together with this mistake can be deadly.
>
> Cobra is a robust plane, designed for aerobatics. Because of this
> purpose wings are really heavy. Flight characteristics are friendly,
> no bad habit like at stdCirrus (all moving tail). Performance is
> around dry stdCirrus, stdJantar.
>
> Wheel retraction system is a tricky rotating mechanism, careful
> maintenance is needed for proper operation.
>
> Instrument panel is small, limited space for instruments.
>
> Baggage compartment is big, XC equipment can fit easily.
>
> Not all Cobra is fired with CG hook! Winch launch with nose hook is
> much lower.
>
> It's a wooden plane with some composite material. Surface waveness can
> change a lot by temperature, humidity. So don't worry if your nice
> Cobra looks ugly one day, it will be nice again after a while;)
>
> Conenction mechanism below the control stick is a bit weak. It's a
> screw adjusted conical system and as dusk usually get's into that
> place regular adjustment is needed. Usually this adjustment is a
> tricky balancing between low control forces and small play.
>
> If you are interested about some pictures here is my Cobra page:
>
> http://bauerj.fw.hu/Cobra15/

http://www.sylacaugasoaring.com/SZD%20COBRA%20WARNING.htm

[Frank Whiteley]

On Jul 27, 3:21*pm, Frank Whiteley > wrote:
> On Jul 27, 12:46*pm, wrote:
>
>
>
> > I think there is a misunderstanding. There are two main screws at the
> > spar but non of the similar to the linked element.
>
> > On of them is vertical and similar to the IS28B2 main pin mechanism.
> > This attach and secure the two wings. It's unlikely to have failure
> > here.
>
> > Second one is horizontal behind the pilots head. This mechanism adjust
> > the wings horizontal play. This has to be fastened and secured after
> > assembly. One of my friend took off without this step... I can imagine
> > that high stress together with this mistake can be deadly.
>
> > Cobra is a robust plane, designed for aerobatics. Because of this
> > purpose wings are really heavy. Flight characteristics are friendly,
> > no bad habit like at stdCirrus (all moving tail). Performance is
> > around dry stdCirrus, stdJantar.
>
> > Wheel retraction system is a tricky rotating mechanism, careful
> > maintenance is needed for proper operation.
>
> > Instrument panel is small, limited space for instruments.
>
> > Baggage compartment is big, XC equipment can fit easily.
>
> > Not all Cobra is fired with CG hook! Winch launch with nose hook is
> > much lower.
>
> > It's a wooden plane with some composite material. Surface waveness can
> > change a lot by temperature, humidity. So don't worry if your nice
> > Cobra looks ugly one day, it will be nice again after a while;)
>
> > Conenction mechanism below the control stick is a bit weak. It's a
> > screw adjusted conical system and as dusk usually get's into that
> > place regular adjustment is needed. Usually this adjustment is a
> > tricky balancing between low control forces and small play.
>
> > If you are interested about some pictures here is my Cobra page:
>
> >http://bauerj.fw.hu/Cobra15/
>
> http://www.sylacaugasoaring.com/SZD%20COBRA%20WARNING.htm

http://www.ntsb.gov/ntsb/GenPDF.asp?id=ATL07LA066&rpt=fa

[[email protected]]

Uhh, horror...

So it was the main pin. I will ask around the local cobra, foka and IS
pilots. These pictures are really scarry!