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No thanks. This is not at all a critical design. Since it is a wet wing I have had to add an extra ply that is completely redundant and WAY overbuilds the structure. Also the LS-1 wing is a little shorter, reducing landing loads somewhat. I had my buddy who is a design engineer at SCALED Composites run the ply schedule through his computer and he also said it's overbuilt, though the actual structure will likely be lighter because it is pre-preg with much tighter resin control. Yes, we've built and tested coupons.
On Thu, Sep 16, 2021 at 12:44 PM Rob de Bie <robdebie@...
Nice site, decent data. But most applications look mostly cosmetic and/or low loaded. I think you
are pioneering with the material, make really sure that you are safe! Like with those hot/wet
specimens to check long-term resin adhesion. Should I look up that article to give you some guidance?
On 16 Sep 2021 20:27, Robert Cringely wrote:
> It seems to be working fine for me: https://lingrove.com/ekoa-prepregs
> On Thu, Sep 16, 2021 at 11:04 AM Rob de Bie <robdebie@... <mailto:robdebie@...>> wrote:
> Bob, when you mentioned flax fibers I peaked my ears! I've worked a bit with flax composites
> some 15
> years ago. Is the material mature enough to use in an aircraft? I remember problems like no
> sizings being available to optimize fiber-resin adhesion, moisture content during curing leading to
> degraded resin adhesion & quality, and moisture absorption during use leading to lower properties.
> Sounded to me like it would a lot more development before it would be safe to fly. But it was 15
> years ago.
> I also remember reading in an eighties issue of 'Homebuilt aircraft' magazine that hot-wet test
> specimens could be good indicator of the longer-term quality of the fiber-resin adhesion. Sounded
> reasonable to me.
> On 16 Sep 2021 17:39, Robert Cringely wrote:
> > Thanks! I’m using a no-name 680cc aluminum air-cooled V2 diesel to which I am adding a tiny
> > turbocharger and intercooler. What’s changed since you looked is probably direct injection.
> > weight is around 50kg. I’m adding a belt drive from Ace Redrives in India. It’s 1:1 because I
> > need a slower prop but I do need to raise the thrust line and to isolate the prop loads from the
> > mystery metal Chinese crankshaft. I’m probably a year from flying, by which time I will have
> > replaced most of the airframe with vacuum-bagged pre-preg. It’s not carbon or glass — it’s flax
> > fiber, which fits right between e-glass and s-glass in performance, with a little Coremat
> added for
> > stiffness.
> > Bob
> > On Thu, Sep 16, 2021 at 8:16 AM Hot Wings via groups.io <http://groups.io> <http://groups.io
> <http://groups.io>> <email@example.com <mailto:firstname.lastname@example.org>
> > <mailto:email@example.com <mailto:firstname.lastname@example.org>>> wrote:
> > What diesel engine are you considering? I looked at the V-twin Chinese diesels more than a
> > decade ago and discarded the idea as not practical.
> > There are some interesting marine 2 stroke diesel development projects nearing market
> > introduction that may provide some of us with a 100LL option.
> > Look up Alan Thayer (sp) in the archives. He had an LS-1 canard designed using Graphlite
> > rods.Attached is a *.ZIP file of some of his work. Graphlite is no longer a practical
> source of
> > carbon rods for us as they are quite unwilling to sell rolled lengths of material. The
> > suppliers are willing and at a considerable savings in cost. Preliminary tests have
> > the quality/strength is as good as the US sourced material.