Hey everybody,

I want to build a front wing depending on the original part with Prepreg. For sure it has to be a two part mould. My problem is how to get the two parts bonded because the edge line will be only about 1mm and so it is too small to make a bonding. I have some ideas and hope to get some input:

1. after making the two parts I go for a smaller version. I make a second carbon part using the first carbon Part as „mould“. This way I get a smaller part which can be used as connecting part to bond the two main parts together.

2. I lay up the two moulds with a little overlap on one part, put them together, insert a bladder and make a small hole on the downside to inflate the bladder. But actually I have never tried this technique. I get it in theory but I do not now what to use as bladder and how much pressure is necessary.

3. same as number two but using a silicone plug which should expand with heat and produce enough pressure for the Prepreg. In this case I would be happy to get some tips about how to make the silicone plug, especially where to get the right material.

4. last idea: filling each mould with polystyrene foam and use the foam to produce pressure. But I do not know if the foam will produce enough pressure and how to fix the flaps.

So you See, lots of questions :] perhaps some of you understand what I try to do and give me some input.

Have a nice Weekend!

Aerofoils are easy to produce as one piece using conventional vacuum bags, unless this is for an RC car or something very small? 

The part is about 60cm x 30 cm so not very small. But I cannot imagine how to make it in one piece because it has gloss surface all around!?

Leave the end plates out when making the mould so that it is just the upper and lower aerofoil surfaces. The ends will be open when the piece is finished, like so:



Lay up each half, do the bottom half with an overlap. Before closing the mould, lay tube style vacuum bag on the bottom half of the mould with plenty of excess out each end, fold the overlap carbon inwards so that it sits slightly over the vacuum bag and wont get pinched in the mould, then close the mould being careful not to pinch the vacuum bag or the overlap carbon especially on the trailing edge.

Then simply place the entire mould inside another tube style vacuum bag, and seal the ends of the inner vac bag to the ends of the outer vac bag. When you pull a vacuum, the outer bag will pull down on the outside of the mould, and the inner bag will pull outwards against the inside of the mould.

After curing, simply trim it up and bond in your end plates.

That is a great tip, thanks a lot! Unfortunately I think this will not work on my part. I add some photos...!

That looks more of a splitter than conventional aerofoil.  If the detail is important on both sides, then in effect take a mould of each side and lay it up in 2 halves and bond together.  If you are careful in the moulding, you may be able to create a bonding lip or joggle on one half to give a nice bonding surface area.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I agree it is a splitter with end plates, not a front wing. But it's small size makes me wonder what it is off - it honestly doesn't look very functional to me.

Regardless, I do think this has to be done as two pieces with a joggle joint as Warren suggests. Trying to do it as one piece is a lot of work/cost for very little gain. 

+x

 

Hanaldo - 8/5/2019 12:46:50 PM

I agree it is a splitter with end plates, not a front wing. But it's small size makes me wonder what it is off - it honestly doesn't look very functional to me.

Regardless, I do think this has to be done as two pieces with a joggle joint as Warren suggests. Trying to do it as one piece is a lot of work/cost for very little gain. 

Yes it is a splitter, sorry wrong wording. I think it has a function because it splits the air to two channels - but thats not why I am trying to make a carbon part out of it

So I come back to your idea to make it as one piece. I would think that your idea above would be a problem to do here because the ends are not flat!?

Do you have an idea how to make such a lip in the mould? You Said make it careful which is a good advice, but I am not sure how to do that...

No more ideas?