You open a big can of worms here. If you are not going to use a proven
method of constructing the hoop landing gear, then you are designing
your own landing gear. If you are qualified to do so, great...if not,
you have to be willing to accept the risk of failure. Why do you want
the gear to have more tension strength? Have you ever heard of a hoop
I am not an engineer, but CF and fiberglass have different properties.
Important for this application is that CF is more rigid than the
fiberglass. If 6-8 layers of CF is insufficient to handle the entire
landing load, it will fail and the load will need to be carried by the
fiberglass. If the fiberglass (because it is thinner when you replaced
it with CF) is unable to accept the entire load, it will also fail. My
suggestion would be to stick with either CF or fiberglass for this
application. If you build the entire gear from CF, it will be lighter,
but much stiffer and more costly (and you once again on your own because
this has not been done on the Dragonfly before).
All Dragonfly hoop landing gears are made from 3" wide unidirectional
roving E fiberglass that is 22 ounces per yard (Aircraft Spruce part
number 01-06800 or Wicks part number 1600-3). It is very thick glass
that comes on a spool.
] On Behalf Of shaffer.jessie
Sent: Sunday, November 30, 2008 11:30 PM
Subject: [Dragonflylist] Re: Hoop Gear Layup & Cloth Orientation
Thanks Dave......I see what what your saying. Although I have one
more question. Does it matter which cloth (BID or UNI) is used? As
long as the major fibers run the length of the gear? I have also
been considering using some unidirectional carbon fiber on the first
6 or 8 layers layed into the form to give it some extra tension
--- In Dragonflylist@yahoogroups.com
<mailto:Dragonflylist%40yahoogroups.com> , "Dave Morris" <BigD@...>
> No, he used unidirectional "tape", which is sold in 3 inch width
and ALL the
> fibers run the length of the gear. He slit the tape in half to
> 1.5 inch widths that could be laid next to the 3 inch width to
> total 4.5 inch width, and alternated overlapping those. The
> nature of the tape is what gives it strength.
> When I did mine, I finished it up by wrapping several additional
> bidirectional over the top, to give it a smoother finish mostly,
> I felt that the gear should have some strength across the span of
> to resist torsional loads caused by FOD on the runway, etc.,
> was done entirely without any engineering calculations.
> Dave Morris
> -----Original Message-----
> From: Dragonflylist@yahoogroups.com
> On Behalf Of shaffer.jessie
> Sent: Sunday, November 30, 2008 7:50 PM
> To: Dragonflylist@yahoogroups.com
> Subject: [Dragonflylist] Hoop Gear Layup & Cloth Orientation
> To All,
> I've searched all the past messages for any information on the
> cloth fiber orientation for Gene Divincenzo's hoop gear design.
> Unfortunately I didn't have much luck. According to Gene's notes
> (published in DBFN #43), it appears (for the first part of the
> that he used continuous strips of cloth (i.e. from one end to the
> other) for the layup until he reached a thickness of 5/8". This
> information, however nowhere have I been able to find any
> on the fiber orientation of these layups discussed. Does anyone
> any information they would be willing to share? As near as I can
> he used 10 oz. BID cloth with one set of fibers running with the
> of the gear and of course, the other set is 90 degrees to this.
> However, I don't know if there is a whole lot of torsional strength
> generated in this configuration. Undoubtedly, there will be some
> torsion on this gear. Any information from anyone would be helpful.
> Yahoo! Groups Links
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