Pre-Preg

On Tuesday, 6 December 2016 08:45:13 UTC+1, Fraser Wilson wrote:
Three further points with pre preg;-
1-Uni directional (UD) pre-preg, which is extensively used in wings, is
difficult
to form into compound curves;- it wrinkles
2-stray fibres, with pre-preg stray fibres can puncture the vac bag. The
wing
skins don't come out of the moulds until after the wings have been fully
glued
together. It's a bad day to discover a single stray fibre has killed the
vacuum
during the cure of a skin and you've just glued it to a good
spar/skin/installed
controls etc
3 - wet lay up wings post cure at 60C, normally out of mould. Pre-Preg
cures
at least 80C maybe hotter but this must be done in the mould. This means
the part and mould thermal expansion must be closely matched and the
longer the part , the more compound curves, the more difficult this
becomes.

Dry fibre resin infusion probably offers the best way forward as it can
provide
similar fibre fractions to pre preg but without the above and earlier
mention
drawbacks.

Fraser


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.

You would cure the skins then glue the rest in. Well, this would be my approach. The spar can be co-cured in there if you like. Makes for easy small steps in manufacturing.
Similar way to the concept behind a F1 car. Outersking, honeycomb and inserts, innerskin.

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

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.

On Thursday, 1 December 2016 22:03:22 UTC+1, Jonathan St. Cloud wrote:
Just wondering why glider are not made with pre-preg. Seems like it would save weight.

Having done 10 years working in Formula 1 making the cars solely from Prepreg and then another 6 years in aerospace making a payload fairing for a well know rocket launcher, I can say that the preconceived idea that prepreg is expensive is wrong.
You also don't need an autoclave to cure it

If you were willing to invest just a little money your raw material usage, and you reproduce-ability would increase no end.
Also, you could happily do a post cure on the parts and paint them any colour you like, just like in Formula 1.

These guys seem to think this will work

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

On Thursday, December 15, 2016 at 12:20:27 PM UTC-8, Ross wrote:
These guys seem to think this will work...

Well, of course it will work. When you have a billionaire footing the bills, you can make anything work. The real question is, does it make enough difference to justify the extra expense in the absence of such extraordinary measures?

I wonder if anyone said the same thing about computers in the early days, Bob!

On Thu, 15 Dec 2016 20:57:17 -0800, roel.baardman wrote:

I wonder if anyone said the same thing about computers in the early
days, Bob!

Unlikely that anybody did.

The very first electronic computers were built for code-breaking and to
calculate artillery range tables. Yes, these tasks could be done
manually, but not nearly as fast. Colossus played a major part in winning
WW2 while ENIAC went on from generating range tables to help design
second generation nukes: the Fat Man design calculations were done using
a roomful of IBM card equipment. See Richard Fyneman's books for more
detail.

The first commercial computers were built by Lyons in the UK. Lyons was
the Starbucks of its day, and used the first machine to streamline bakery
production for the next day's teashop requirements. That was a success
from day one, at least partly because they knew exactly what they wanted
the machine to do and the company already had a solid background in
process optimisation.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Friday, December 16, 2016 at 5:24:30 AM UTC-6, Martin Gregorie wrote:
On Thu, 15 Dec 2016 20:57:17 -0800, roel.baardman wrote:

I wonder if anyone said the same thing about computers in the early
days, Bob!

Unlikely that anybody did.

The very first electronic computers were built for code-breaking and to
calculate artillery range tables. Yes, these tasks could be done
manually, but not nearly as fast. Colossus played a major part in winning
WW2 while ENIAC went on from generating range tables to help design
second generation nukes: the Fat Man design calculations were done using
a roomful of IBM card equipment. See Richard Fyneman's books for more
detail.

The first commercial computers were built by Lyons in the UK. Lyons was
the Starbucks of its day, and used the first machine to streamline bakery
production for the next day's teashop requirements. That was a success
from day one, at least partly because they knew exactly what they wanted
the machine to do and the company already had a solid background in
process optimisation.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Very unfortunate that these early UK computers never caught on, Martin. I hear rumors that you guys couldn't figure out how to make them leak oil?

Who is funding this project. looks very interesting.
On Thursday, December 15, 2016 at 12:20:27 PM UTC-8, Ross wrote:
These guys seem to think this will work

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

Lucas: Prince of Darkness

Lucas 3-position switch:

Dim
Flicker
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