To profile or not to profile

[[email protected]]

My Speed Astir's wings show a considerable amount of waviness at the
spar caps and every rib. There also appears to have been some repair
work on a leading edge, and the profile is noticeably NOT the same as
the other wing.
I have Compufoil Pro, which will outpout CNC mill files for the
templates, and a friend with a CNC mill, willing to produce the
templates. I will almost certainly take care of the leading edge
issues, but I'm waffling about undertaking a full wing re-profile. On
one hand, you want your glider to be as good as it can be. On the
other hand, I don't fly contests, and I'm pretty sure the pilot is
causing more loss of performance than the extra drag from the waves in
the profile.
Opinions??

BTW, the single biggest improvement I've made to date is the addition
of a flight recorder and a iPAQ with XCSoar. That combo made it
immediately clear that I was being too conservative (chicken!)

Jim

[John Sinclair]

I'd just do the leading edge, Jim. The first 4' are
critical, Schueman proved that when he modified the
Hutter airfoil on his H-301 Libelle by changing the
first 4', or so and left the rest alone.
JJ

At 20:18 08 August 2007, wrote:
>My Speed Astir's wings show a considerable amount of
>waviness at the
>spar caps and every rib. There also appears to have
>been some repair
>work on a leading edge, and the profile is noticeably
>NOT the same as
>the other wing.
> I have Compufoil Pro, which will outpout CNC mill
>files for the
>templates, and a friend with a CNC mill, willing to
>produce the
>templates. I will almost certainly take care of the
>leading edge
>issues, but I'm waffling about undertaking a full wing
>re-profile. On
>one hand, you want your glider to be as good as it
>can be. On the
>other hand, I don't fly contests, and I'm pretty sure
>the pilot is
>causing more loss of performance than the extra drag
>from the waves in
>the profile.
> Opinions??
>
> BTW, the single biggest improvement I've made to date
>is the addition
>of a flight recorder and a iPAQ with XCSoar. That combo
>made it
>immediately clear that I was being too conservative
>(chicken!)
>
>Jim
>
>

[Jack[_4_]]

Add the pilot losses and the wing losses, and... It's a large job.
Something you just have to be the judge of... Do you have several
months to do this? I easily spent 500 hours profiling the wings of an
HP-14, and had to sell it due to promotions and moves, (i.e. loss of
shop space, etc.) If you've got time, go for it...

Jack Womack

[John Sinclair]

Hmmmmm,
When I typed the sympol for for inches (') , the system
changed it to feet (') ..............anyway, the first
4 INCHES are important, not the first 4 FEET!
JJ

At 20:18 08 August 2007, wrote:
>My Speed Astir's wings show a considerable amount of
>waviness at the
>spar caps and every rib. There also appears to have
>been some repair
>work on a leading edge, and the profile is noticeably
>NOT the same as
>the other wing.
> I have Compufoil Pro, which will outpout CNC mill
>files for the
>templates, and a friend with a CNC mill, willing to
>produce the
>templates. I will almost certainly take care of the
>leading edge
>issues, but I'm waffling about undertaking a full wing
>re-profile. On
>one hand, you want your glider to be as good as it
>can be. On the
>other hand, I don't fly contests, and I'm pretty sure
>the pilot is
>causing more loss of performance than the extra drag
>from the waves in
>the profile.
> Opinions??
>
> BTW, the single biggest improvement I've made to date
>is the addition
>of a flight recorder and a iPAQ with XCSoar. That combo
>made it
>immediately clear that I was being too conservative
>(chicken!)
>
>Jim
>
>

[[email protected]]

On Aug 8, 1:39 pm, John Sinclair
> wrote:
> Hmmmmm,
> When I typed the sympol for for inches (') , the system
> changed it to feet (') ..............anyway, the first
> 4 INCHES are important, not the first 4 FEET!
> JJ
>
> At 20:18 08 August 2007, wrote:
>
>
>
> >My Speed Astir's wings show a considerable amount of
> >waviness at the
> >spar caps and every rib. There also appears to have
> >been some repair
> >work on a leading edge, and the profile is noticeably
> >NOT the same as
> >the other wing.
> > I have Compufoil Pro, which will outpout CNC mill
> >files for the
> >templates, and a friend with a CNC mill, willing to
> >produce the
> >templates. I will almost certainly take care of the
> >leading edge
> >issues, but I'm waffling about undertaking a full wing
> >re-profile. On
> >one hand, you want your glider to be as good as it
> >can be. On the
> >other hand, I don't fly contests, and I'm pretty sure
> >the pilot is
> >causing more loss of performance than the extra drag
> >from the waves in
> >the profile.
> > Opinions??
>
> > BTW, the single biggest improvement I've made to date
> >is the addition
> >of a flight recorder and a iPAQ with XCSoar. That combo
> >made it
> >immediately clear that I was being too conservative
> >(chicken!)
>
> >Jim- Hide quoted text -
>
> - Show quoted text -

Inches, feet, whatever it takes.

[Lew Hartswick]

John Sinclair wrote:
> Hmmmmm,
> When I typed the sympol for for inches (') , the system
> changed it to feet (') ..............anyway, the first
> 4 INCHES are important, not the first 4 FEET!
> JJ

Intresting!! I'm going to try both and see what shows up.
Inches is the quote mark """"""" looks good here ,
Foot the apostrophe ''''''' looks OK on "up link" :-)
Now to see what shows up on the news group.
...lew...

[Stewart Kissel]

Well JJ is the man ...so 4' sounds a lot easier then
the whole thing.

jimphoenix.com has a tremendous amount of imaging and
narrative on the work he did on a Nimbus 3...well worth
a peak

[[email protected]]

On Aug 8, 7:12 pm, Stewart Kissel
> wrote:
> Well JJ is the man ...so 4' sounds a lot easier then
> the whole thing.
>
> jimphoenix.com has a tremendous amount of imaging and
> narrative on the work he did on a Nimbus 3...well worth
> a peak

Worth more than a peak. I've spent many hours on his site. Anyone
even vaguely interested in gelcoat work, 1-26 restorations, or wooden
boat restorations would benefit greatly from Jim's work.

[Doug Hoffman]

If you are just doing the first 4 inches or so with precise templates
(and I agree that from a results per effort view this could be the
right way to go), I would seriously consider eliminating the chordwise
waves on the rest of the wing surface. For laminar airflow you want
no more than a .004 inch bump or dip in 2 inches. You can easily
measure this with a dial indicator set up as Richard Johnson shows.
Using filler and sanding splines (always sand at 45 degrees to the
chordwise direction) it is not that hard to achieve this level of low
waviness. This lack of waviness is likely more important than
fidelity to the specified airfoil contour once you are farther than
about 4 inches from the LE.

Be prepared for a lot of work. But the results can be spectacular.

Regards,

Doug

[Udo]

On Aug 8, 4:12 pm, wrote:
> My Speed Astir's wings show a considerable amount of waviness at the
> spar caps and every rib. There also appears to have been some repair
> work on a leading edge, and the profile is noticeably NOT the same as
> the other wing.
> I have Compufoil Pro, which will outpout CNC mill files for the
> templates, and a friend with a CNC mill, willing to produce the
> templates. I will almost certainly take care of the leading edge
> issues, but I'm waffling about undertaking a full wing re-profile. On
> one hand, you want your glider to be as good as it can be. On the
> other hand, I don't fly contests, and I'm pretty sure the pilot is
> causing more loss of performance than the extra drag from the waves in
> the profile.
> Opinions??
>
> BTW, the single biggest improvement I've made to date is the addition
> of a flight recorder and a iPAQ with XCSoar. That combo made it
> immediately clear that I was being too conservative (chicken!)
>
> Jim

The Speed Astir is one of the few gliders that can be improved
substantially. The 662 airfoil suffers from an upper surface pressure
recovery problem that has been know for along time and Richard Eppler
him self recommended a turbulator on the "top surface" at 65% chord.
Naturally if the wing has a dip over the spar this turbulator will be
of no use, as the laminar flow is already kaput before it gets there.
If I were you I would follow the advise of Doug Hoffman. The other
improvement that would pay big dive would be a winglet, due to its
relative small aspect ratio und big tip chord it would benefit
proportionally more then other gliders of its vintage.

One other note Richard Eppler designed a replacement airfoil call
E673 for the E662, which can be easily arrived at by sanding the
existing one.

Allow 400 hour for the complete job. I would work on it in 2 stages
sanding and painting. Even in an unfinished sanded only state you
would see good results. Most of the filling can be done with a high
build primer. Full chord templates would be helpful but if you only
redoing the first 4 inches and fill in the spar dip then a few small
templates are needed. The spar dip can be done with a flexible steel
ruler and double check with a gage.
Have fun
Udo

[[email protected]]

On Aug 9, 9:05 am, Udo > wrote:
> On Aug 8, 4:12 pm, wrote:
>
>
>
>
>
> > My Speed Astir's wings show a considerable amount of waviness at the
> > spar caps and every rib. There also appears to have been some repair
> > work on a leading edge, and the profile is noticeably NOT the same as
> > the other wing.
> > I have Compufoil Pro, which will outpout CNC mill files for the
> > templates, and a friend with a CNC mill, willing to produce the
> > templates. I will almost certainly take care of the leading edge
> > issues, but I'm waffling about undertaking a full wing re-profile. On
> > one hand, you want your glider to be as good as it can be. On the
> > other hand, I don't fly contests, and I'm pretty sure the pilot is
> > causing more loss of performance than the extra drag from the waves in
> > the profile.
> > Opinions??
>
> > BTW, the single biggest improvement I've made to date is the addition
> > of a flight recorder and a iPAQ with XCSoar. That combo made it
> > immediately clear that I was being too conservative (chicken!)
>
> > Jim
>
> The Speed Astir is one of the few gliders that can be improved
> substantially. The 662 airfoil suffers from an upper surface pressure
> recovery problem that has been know for along time and Richard Eppler
> him self recommended a turbulator on the "top surface" at 65% chord.
> Naturally if the wing has a dip over the spar this turbulator will be
> of no use, as the laminar flow is already kaput before it gets there.
> If I were you I would follow the advise of Doug Hoffman. The other
> improvement that would pay big dive would be a winglet, due to its
> relative small aspect ratio und big tip chord it would benefit
> proportionally more then other gliders of its vintage.
>
> One other note Richard Eppler designed a replacement airfoil call
> E673 for the E662, which can be easily arrived at by sanding the
> existing one.
>
> Allow 400 hour for the complete job. I would work on it in 2 stages
> sanding and painting. Even in an unfinished sanded only state you
> would see good results. Most of the filling can be done with a high
> build primer. Full chord templates would be helpful but if you only
> redoing the first 4 inches and fill in the spar dip then a few small
> templates are needed. The spar dip can be done with a flexible steel
> ruler and double check with a gage.
> Have fun
> Udo- Hide quoted text -
>
> - Show quoted text -

Thanks Udo,
I will look into the E673. Winglets appeal to me, but I lack the
background to do the design work. I've read the Masak article
numerous times, but several aspects of the design work are just over
my head.
At the very least I will have full templates produced, fill the spar
dip, and profile the forward section of the wing.

Jim

[Dan G]

On Aug 9, 5:05 pm, Udo > wrote:
> The Speed Astir is one of the few gliders that can be improved
> substantially.

Do all single-seat Astirs use the same wing?


Dan

[toad]

On Aug 10, 5:49 am, Dan G > wrote:
> On Aug 9, 5:05 pm, Udo > wrote:
>
> > The Speed Astir is one of the few gliders that can be improved
> > substantially.
>
> Do all single-seat Astirs use the same wing?
>
> Dan

No,

The Grob 102 and 103 use the E603 airfoil.

Todd Smith
3S

[[email protected]]

On Aug 10, 3:41 am, toad > wrote:
> On Aug 10, 5:49 am, Dan G > wrote:
>
> > On Aug 9, 5:05 pm, Udo > wrote:
>
> > > The Speed Astir is one of the few gliders that can be improved
> > > substantially.
>
> > Do all single-seat Astirs use the same wing?
>
> > Dan
>
> No,
>
> The Grob 102 and 103 use the E603 airfoil.
>
> Todd Smith
> 3S

The Speed Astir wing is also flapped, and 123.4 sq. feet, as opposed
to the 133.5 sq. feet of the unflapped "other" Grob single seaters.

[[email protected]]

Jim,

I'm about to purchase a Grob 104 that will need a refinish in the next few years. I found this thread while doing research and was wondering if you ever had the leading edge templates made. I would be willing to rent them from you at some point whenever I finally have to bite the bullet and start the refinish.

Can you tell me how your project went and if you ever added winglets as well? Any hints or suggestions would be greatly appreciated. I plan to add the turbulators as soon as I get the glider as they were removed for a quicky spray job and never re-installed.

Thanks,

Greg Delp
203-565-5117


On Wednesday, August 8, 2007 4:12:23 PM UTC-4, wrote:
> My Speed Astir's wings show a considerable amount of waviness at the
> spar caps and every rib. There also appears to have been some repair
> work on a leading edge, and the profile is noticeably NOT the same as
> the other wing.
> I have Compufoil Pro, which will outpout CNC mill files for the
> templates, and a friend with a CNC mill, willing to produce the
> templates. I will almost certainly take care of the leading edge
> issues, but I'm waffling about undertaking a full wing re-profile. On
> one hand, you want your glider to be as good as it can be. On the
> other hand, I don't fly contests, and I'm pretty sure the pilot is
> causing more loss of performance than the extra drag from the waves in
> the profile.
> Opinions??
>
> BTW, the single biggest improvement I've made to date is the addition
> of a flight recorder and a iPAQ with XCSoar. That combo made it
> immediately clear that I was being too conservative (chicken!)
>
> Jim