I quickly calculated that a 0.56mm wide strip of 19gsm carbon prepreg has
the same mass as 3mil boron (including 1 mg glue per 10"). The strip of
carbon actually has a slightly higher stiffness (it is marginally, but
still).
Kevin
2015-01-19 8:43 GMT+01:00 Kevin Lamers <kevin.lamers_at_gmail.com>:
> 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 Mon Jan 19 2015 - 00:08:20 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:48 CET