Vacuum Bagging honeycomb core

[ian_upton]

Does honeycomb core material lend itself to vacuum bagging?

I am considering trying this when I replace a cabin bulkhead on an old Bertram 25.

The finished surface will be painted, so I thought the peelply surface from the vacuum bag would give a nice surface to start with.

I have access to partial sheets of Corecell at a considerable discount (Noah's in Toronto) and am also wondering if two pcs butted against each other would be sufficient or would this create a weak panel?

Thanks,

Ian.

[wet feet]

Be aware that there is more than one type of honeycomb.I have encountered Nomex and Aluminium in vacuum bagging situations and both do a satisfactory job.You need to be sure that the material you have access to is of the correct density to provide the strength for the job and that it has the flexibility to conform to any necessary shape.

[marshmat]

Corecell is not a honeycomb, it is a closed-cell foam. It is probably suitable for your bulkhead replacement.
I have never seen a satisfactory honeycomb core job done without vacuum bagging, on anything but a horizontal flat plate. Curved or vertical parts with honeycombs simply have to be done under vacuum bag in order to work properly, unless you want the finished product to be 75% resin and way overweight. Nomex and aluminum honeycombs both have a tendency to suck the liquid resin out of the skins; a good layup is not nearly as easy as with solid fibreglass. Honeycombs are complex materials and specifying an appropriate one for a particular job requires a good understanding of the stress distributions within the part.
A peel-ply surface has a slight texture, generally comparable to 150-220 grit sandpaper in terms of how much it deviates from perfectly smooth. It is paintable, but to get a mirror-smooth finish will require that you fair it with a microballoon filling compound.

[ian_upton]

That's for the replies.

I guess I was vague in my question. I understand that corecell and honeycomb are two different materials.

My corecell question is will you lose much in stiffness by having multiple pcs of core material within the panel or should I spend the $$ for a continous sheet?

If I am bagging a wet laminate (not infusion) do I need to prime the corecell with resin and let it kick?

My concern with honeycomb was if the voids in the honeycomb would suck up the resin and create a honeycomb cells full of resin.

Thanks,

Ian.

[Bayport_Bob]

Honeycomb cores are typically used with prepreg materials where the layup is cured in an autoclave or an oven under vacuum. There is minimal resin flow with this type of system and the hollow chambers don't fill up with resin.