Re: Carbon capped spars

From: Kevin Lamers <kevin.lamers_at_gmail.com>
Date: Mon, 19 Jan 2015 08:43:14 +0100

If you have questions on composite construction as applied on outdoor
models, don't hesitate to contact me off list. I think the main reason for
de-laminating spar caps is balsa being applied with the grain in the wrong
direction. The balsa grain should be vertical, so perpendicular to the
direction of the caps.

Yep, let's get back on topic ;-)

I disagree that anything with epoxy will be too heavy for F1D (especially
with the new rules). Already people are construction complete propellers,
vp's, motor tubes and wing-posts from carbon fibre (and that is with
epoxy). I also think in the case of wing spars, using carbon laminated
balsa isn't necessarily lighter than a construction with boron. But I think
it might improve consistency and ease of production, since a whole plate
could be laminated from which the spars are sliced.

The actual failure mode could be anything, from core shear, carbon
breakage, carbon buckling to core crushing. The mode that actually occurs
is hard to determine and depends on a lot of parameters.

Kevin

2015-01-18 3:31 GMT+01:00 Ron Williams groncan_at_gmail.com
[Indoor_Construction] <Indoor_Construction_at_yahoogroups.com>:

>
>
> The breakage in a carbon fiber topped spar is going to be in shear . . .
>
> On Sat, Jan 17, 2015 at 5:09 PM, wdgowen_at_gmail.com [Indoor_Construction] <
> Indoor_Construction_at_yahoogroups.com> wrote:
>
>>
>>
>> This discussion has been interesting but I believe the original question
>> was concerning spars for indoor models and I would guess that it was aimed
>> at F1D construction in particular. So here's my take on the use of carbon
>> laminates (and some of you may prove this incorrect):
>>
>> LPP, OPP, F1M - carbon tubes, rods or balsa/carbon laminates are all good
>> and logical choices.
>>
>> F1D, HLS, F1R - anything that has epoxy in it is too heavy. Carbon thread
>> or boron applied with acetate glue to balsa is about as heavy as these
>> classes can stand.
>>
>
>
>
Received on Sun Jan 18 2015 - 23:43:15 CET