Pre-Preg

On Tuesday, December 6, 2016 at 6:15:46 PM UTC+1, wrote:
On Monday, December 5, 2016 at 7:59:28 PM UTC-5, Casey wrote:
On Monday, December 5, 2016 at 4:58:14 PM UTC-5, Casey wrote:
On Monday, December 5, 2016 at 2:23:59 PM UTC-5, Jonathan St. Cloud wrote:
For the guys with an engine weight does make a difference. Imagine if the 100 pounds of engine and fuel were offset by construction methods that lowered the empty weight of the glider by even 50-70 pounds. YOu would functionally have the same wing loading range as a pure glider.

Just saying.
On Thursday, December 1, 2016 at 4:09:14 PM UTC-8, wrote:
4 Pretty much nobody cares much about weight, except the little gliders. For all the rest we just want to know how much water can we get in it.

Different building methods in same factory brings several issues I could think of.
Cost of buying and storing different materials, cost of process, possible mistakes in manufacturing, return on investment, different flying characteristics. Just throwing this out there.

Maybe this is why GP decided to put the batteries in the wings. Removal for light days without changing CG. All other FES gliders have batteries behind cockpit and have to fly with batteries.

Putting the batteries in the wings reduces the weight of non lifting parts which means the wing spars and root area don't have to be made as heavy.
UH

And this is exactly why retrofitting an older glider to FES is impossible. With an max weight of non lifting part typically in the range of 230-250kg is it not enough marginal to put in an extra weight of 40-50kg for motor, electronics and battery in the fuselage unless you are a really light weight pilot.
I have asked the FES guys several times if it would be possible to get batteries suitable for wing installation and the answer is no.

On Wednesday, December 7, 2016 at 1:49:59 AM UTC-5, Per Carlin wrote:
On Tuesday, December 6, 2016 at 6:15:46 PM UTC+1, wrote:
On Monday, December 5, 2016 at 7:59:28 PM UTC-5, Casey wrote:
On Monday, December 5, 2016 at 4:58:14 PM UTC-5, Casey wrote:
On Monday, December 5, 2016 at 2:23:59 PM UTC-5, Jonathan St. Cloud wrote:
For the guys with an engine weight does make a difference. Imagine if the 100 pounds of engine and fuel were offset by construction methods that lowered the empty weight of the glider by even 50-70 pounds. YOu would functionally have the same wing loading range as a pure glider.

Just saying.
On Thursday, December 1, 2016 at 4:09:14 PM UTC-8, wrote:
4 Pretty much nobody cares much about weight, except the little gliders. For all the rest we just want to know how much water can we get in it.

Different building methods in same factory brings several issues I could think of.
Cost of buying and storing different materials, cost of process, possible mistakes in manufacturing, return on investment, different flying characteristics. Just throwing this out there.

Maybe this is why GP decided to put the batteries in the wings. Removal for light days without changing CG. All other FES gliders have batteries behind cockpit and have to fly with batteries.

Putting the batteries in the wings reduces the weight of non lifting parts which means the wing spars and root area don't have to be made as heavy.
UH

And this is exactly why retrofitting an older glider to FES is impossible.. With an max weight of non lifting part typically in the range of 230-250kg is it not enough marginal to put in an extra weight of 40-50kg for motor, electronics and battery in the fuselage unless you are a really light weight pilot.
I have asked the FES guys several times if it would be possible to get batteries suitable for wing installation and the answer is no.

nothing is impossible.

On Wednesday, 7 December 2016 17:49:59 UTC+11, Per Carlin wrote:
And this is exactly why retrofitting an older glider to FES is impossible.. With an max weight of non lifting part typically in the range of 230-250kg is it not enough marginal to put in an extra weight of 40-50kg for motor, electronics and battery in the fuselage unless you are a really light weight pilot.


Not really a problem. Look at the old TOP installs on LS3s and 4s. An AD was issued that increased max weight of non-lifting parts. The tradeoff was a reducing in Vne and other airspeeds. So long as you stayed within CofG limits, then tradeoffs of weight for speed can always be done.

On Thursday, December 8, 2016 at 1:22:15 AM UTC+1, Justin Couch wrote:
On Wednesday, 7 December 2016 17:49:59 UTC+11, Per Carlin wrote:
And this is exactly why retrofitting an older glider to FES is impossible. With an max weight of non lifting part typically in the range of 230-250kg is it not enough marginal to put in an extra weight of 40-50kg for motor, electronics and battery in the fuselage unless you are a really light weight pilot.


Not really a problem. Look at the old TOP installs on LS3s and 4s. An AD was issued that increased max weight of non-lifting parts. The tradeoff was a reducing in Vne and other airspeeds. So long as you stayed within CofG limits, then tradeoffs of weight for speed can always be done.

Well, for us Europeans that fly certified gliders is this not easy. The Type Certificate Holder has to release an AD and for older gliders is this not likley, not unless that you pay for it.

Op dinsdag 6 december 2016 11:58:23 UTC+1 schreef Ross:
I tend to disagree with most of that.
UD is difficult on complex shapes yes, but what is complex about a wing? It is basically straight. If you can laminate it with wet laminate, you can do it with prepreg.


Not really. Wing skins need 45/-45 fibers. Easy enough to put in a single tapered wing, but multiple tapers, fairings or wing tips are pretty awkward for either prepregs or thick BIAX/TRIAX.
Fuselage is worse.

Don't see the issue with postcure. No need for it to be done in the mold with Prepreg. We were postcuring suspension to 180-220 deg C out of the mold and had no issues. They were cured at 130 to start with.
As far as thermal expansion goes, why not make your molds out of tooling prepreg? Works like a charm, and if you have a decent glider you will make plenty of gliders out of the mold and you will always have the same shape. Beats having to rework your molds every couple of years
Pretty expensive to make such a mold since you need a plug that can withstand that temperature too. Solid aluminium requires major adjustment (thermal expansion during cure), inconel is $$$.
That's one of the biggest advantages of infusion. Cure at 30C or so, join parts etc and pull from the molds. Then, with a very slow ramp-up (5C/hour) you can postcure to 100-120C and you have a plane that can be painted any color and won't need rework for spar bumps and other annoying issues.

At 18:43 08 December 2016, J. Nieuwenhuize wrote:
Op dinsdag 6 december 2016 11:58:23 UTC+1 schreef Ross:
I tend to disagree with most of that.
UD is difficult on complex shapes yes, but what is complex about a
wing?
=
It is basically straight. If you can laminate it with wet laminate, you
can=
do it with prepreg.
=20

Not really. Wing skins need 45/-45 fibers. Easy enough to put in a single
t=
apered wing, but multiple tapers, fairings or wing tips are pretty
awkward
=
for either prepregs or thick BIAX/TRIAX.
Fuselage is worse.

Don't see the issue with postcure. No need for it to be done in the
mold
=
with Prepreg. We were postcuring suspension to 180-220 deg C out of the
mol=
d and had no issues. They were cured at 130 to start with.
As far as thermal expansion goes, why not make your molds out of
tooling
=
prepreg? Works like a charm, and if you have a decent glider you will
make
=
plenty of gliders out of the mold and you will always have the same
shape.
=
Beats having to rework your molds every couple of years
Pretty expensive to make such a mold since you need a plug that can
withsta=
nd that temperature too. Solid aluminium requires major adjustment
(thermal=
expansion during cure), inconel is $$$.
That's one of the biggest advantages of infusion. Cure at 30C or so, join
p=
arts etc and pull from the molds. Then, with a very slow ramp-up
(5C/hour)=
you can postcure to 100-120C and you have a plane that can be painted
any
=
color and won't need rework for spar bumps and other annoying issues.

I definitely would not take Ros's recommendation of co curing the wing
skins
and spars in one operation . This is just what SH got badly wrong on the
Discus wings when they tried to co cure the caps to the wing skins but
found
they couldn't ensure a satisfactory bond to the spar web when they bonded
the skins together;- was it 70 odd wings sets scraped?

As for a partial cure on a wing cover, remove from mould and final cure at

high temperature, I'm very dubious. In order to assemble the wing skins
together to get the right twist and fit the wing skins must be held to a
high
level of precision. Added to this an individual wing skin is an unbalanced

layup I.e two thick 45's, foam, and one thin bid so its ripe for thermal
distortion. However when the top skin and bottom skins are bonded it
becomes balanced across the wing section. As for the justification that it

works on a 30 (or so) cm part therefore it must work on an 8m I will make
no
further comment.

Yes of course it's possible to build a wing in pre-preg but why? The mould
has
to be made from a more expensive material, more expensive energy is
required to heat it to higher temperature and more expensive manhour time
is required to do all the inter leafing so as to avoid the wrinkling.

Fraser

On Thursday, December 8, 2016 at 6:15:05 PM UTC-5, Fraser Wilson wrote:
At 18:43 08 December 2016, J. Nieuwenhuize wrote:
Op dinsdag 6 december 2016 11:58:23 UTC+1 schreef Ross:
I tend to disagree with most of that.
UD is difficult on complex shapes yes, but what is complex about a
wing?
=
It is basically straight. If you can laminate it with wet laminate, you
can=
do it with prepreg.
=20

Not really. Wing skins need 45/-45 fibers. Easy enough to put in a single
t=
apered wing, but multiple tapers, fairings or wing tips are pretty
awkward
=
for either prepregs or thick BIAX/TRIAX.
Fuselage is worse.

Don't see the issue with postcure. No need for it to be done in the
mold
=
with Prepreg. We were postcuring suspension to 180-220 deg C out of the
mol=
d and had no issues. They were cured at 130 to start with.
As far as thermal expansion goes, why not make your molds out of
tooling
=
prepreg? Works like a charm, and if you have a decent glider you will
make
=
plenty of gliders out of the mold and you will always have the same
shape.
=
Beats having to rework your molds every couple of years
Pretty expensive to make such a mold since you need a plug that can
withsta=
nd that temperature too. Solid aluminium requires major adjustment
(thermal=
expansion during cure), inconel is $$$.
That's one of the biggest advantages of infusion. Cure at 30C or so, join
p=
arts etc and pull from the molds. Then, with a very slow ramp-up
(5C/hour)=
you can postcure to 100-120C and you have a plane that can be painted
any
=
color and won't need rework for spar bumps and other annoying issues.

I definitely would not take Ros's recommendation of co curing the wing
skins
and spars in one operation . This is just what SH got badly wrong on the
Discus wings when they tried to co cure the caps to the wing skins but
found
they couldn't ensure a satisfactory bond to the spar web when they bonded
the skins together;- was it 70 odd wings sets scraped?

As for a partial cure on a wing cover, remove from mould and final cure at

high temperature, I'm very dubious. In order to assemble the wing skins
together to get the right twist and fit the wing skins must be held to a
high
level of precision. Added to this an individual wing skin is an unbalanced

layup I.e two thick 45's, foam, and one thin bid so its ripe for thermal
distortion. However when the top skin and bottom skins are bonded it
becomes balanced across the wing section. As for the justification that it

works on a 30 (or so) cm part therefore it must work on an 8m I will make
no
further comment.

Yes of course it's possible to build a wing in pre-preg but why? The mould
has
to be made from a more expensive material, more expensive energy is
required to heat it to higher temperature and more expensive manhour time
is required to do all the inter leafing so as to avoid the wrinkling.

Fraser

I am aware that some SH wings required inspection of the glue joint between the shear web and the spar cap, and some required repair. I never heard of any being scrapped. They did a great job of dealing with a quality problem caused by a supplier.
SH uses the method of building the spar caps into the skins to this day with good results.
UH

On Friday, 9 December 2016 00:57:51 UTC+1, wrote:
On Thursday, December 8, 2016 at 6:15:05 PM UTC-5, Fraser Wilson wrote:
At 18:43 08 December 2016, J. Nieuwenhuize wrote:
Op dinsdag 6 december 2016 11:58:23 UTC+1 schreef Ross:
I tend to disagree with most of that.
UD is difficult on complex shapes yes, but what is complex about a
wing?
=
It is basically straight. If you can laminate it with wet laminate, you
can=
do it with prepreg.
=20

Not really. Wing skins need 45/-45 fibers. Easy enough to put in a single
t=
apered wing, but multiple tapers, fairings or wing tips are pretty
awkward
=
for either prepregs or thick BIAX/TRIAX.
Fuselage is worse.

Don't see the issue with postcure. No need for it to be done in the
mold
=
with Prepreg. We were postcuring suspension to 180-220 deg C out of the
mol=
d and had no issues. They were cured at 130 to start with.
As far as thermal expansion goes, why not make your molds out of
tooling
=
prepreg? Works like a charm, and if you have a decent glider you will
make
=
plenty of gliders out of the mold and you will always have the same
shape.
=
Beats having to rework your molds every couple of years
Pretty expensive to make such a mold since you need a plug that can
withsta=
nd that temperature too. Solid aluminium requires major adjustment
(thermal=
expansion during cure), inconel is $$$.
That's one of the biggest advantages of infusion. Cure at 30C or so, join
p=
arts etc and pull from the molds. Then, with a very slow ramp-up
(5C/hour)=
you can postcure to 100-120C and you have a plane that can be painted
any
=
color and won't need rework for spar bumps and other annoying issues.

I definitely would not take Ros's recommendation of co curing the wing
skins
and spars in one operation . This is just what SH got badly wrong on the
Discus wings when they tried to co cure the caps to the wing skins but
found
they couldn't ensure a satisfactory bond to the spar web when they bonded
the skins together;- was it 70 odd wings sets scraped?

As for a partial cure on a wing cover, remove from mould and final cure at

high temperature, I'm very dubious. In order to assemble the wing skins
together to get the right twist and fit the wing skins must be held to a
high
level of precision. Added to this an individual wing skin is an unbalanced

layup I.e two thick 45's, foam, and one thin bid so its ripe for thermal
distortion. However when the top skin and bottom skins are bonded it
becomes balanced across the wing section. As for the justification that it

works on a 30 (or so) cm part therefore it must work on an 8m I will make
no
further comment.

Yes of course it's possible to build a wing in pre-preg but why? The mould
has
to be made from a more expensive material, more expensive energy is
required to heat it to higher temperature and more expensive manhour time
is required to do all the inter leafing so as to avoid the wrinkling.

Fraser

I am aware that some SH wings required inspection of the glue joint between the shear web and the spar cap, and some required repair. I never heard of any being scrapped. They did a great job of dealing with a quality problem caused by a supplier.
SH uses the method of building the spar caps into the skins to this day with good results.
UH

Use TB650 as we do in the Formula 1 for tooling.
Most F1 parts require UD and there are no more complex shapes than on an F1 car.
I think a glider would be pretty easy having made about 200 of them whilst working in one of the good Germany manufacturers.

And no, they never scrapped 70 wings. Not sure they scrapped any at all. Not 1 in the entire time I was there

On Monday, December 5, 2016 at 2:23:59 PM UTC-5, Jonathan St. Cloud wrote:
For the guys with an engine weight does make a difference. Imagine if the 100 pounds of engine and fuel were offset by construction methods that lowered the empty weight of the glider by even 50-70 pounds. YOu would functionally have the same wing loading range as a pure glider.

Jonathon is describing my Apis M 15 meter! Only 500 lbs. total including the engine, prop, starter, battery, etc. Has carbon in the wing spar and other areas.

These guys seem to think this will work

https://www.facebook.com/NixusProject/