RE: Seeker Wing Mold

RE: Seeker Wing Mold
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RE: Seeker Wing Mold - 8/13/2004 4:16:14 AM

daven

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From: Andover, MN, USA
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I got the other half in the bag tonight. It went much easier than the first half. Using 5 minute epoxy to glue rohacell together works pretty good if you put a strip of tape at the seam on the bottom and crack the top and apply sparingly amounts of glue.

Also, rather than trying to put the glass on the rohacell in the mold, I did it on a flat table, and them put in the mold. MUCH easier and I am sure I saved at least an ounce of epoxy compared to the bottom half I did last night.

I'm still having issues with the bags leaking at the connector when trying to pull 25 oz of mercury. I just can't get those aerospace composite connectors tight enough on the bag and they leak.

From the time I started cutting fabric, carbon, rohacell, and to the point the mold was in the bag was less than 2 hours. I'm just guessing, but it looks like when I get the hang of this I will be able to do a painted in the mold wing in less than 6 hours.

The problem, is waiting for the epoxy to dry

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Post #: 26

RE: Seeker Wing Mold - 8/13/2004 4:44:15 AM

HighPlains

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From: Over da rainbow, KS, USA
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Dave,

Very interesting stuff, maybe we should shorten Quickie wing span to 48 inches.

How do you prepare the material that goes into the tips? Compound curves look like trouble, but your photos look great and I can't see any seams.

Also looking forward to ailerons

Bob

(in reply to daven)

Post #: 27

RE: Seeker Wing Mold - 8/13/2004 5:35:22 AM

garys

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From: San Diego, CA, USA
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Dave,
The worst part of molded wings if having to wait to see what the very first thing you did (paint) comes out like. The last couple of Proud Bird wing's that Jim Allen's done have come out really cool, but he went nuts until they came out of the mold.
GS

(in reply to HighPlains)

Post #: 28

RE: Seeker Wing Mold - 8/13/2004 3:50:26 PM

Mluvara

Posts: 1425
Joined: 1/14/2002
From: San Jose, CA, USA
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quote:

ORIGINAL: daven
I'm still having issues with the bags leaking at the connector when trying to pull 25 oz of mercury. I just can't get those aerospace composite connectors tight enough on the bag and they leak.

Dave, one option is to have some clay handy to put around the connector if it is leaking. The connectors from aerospace composites work good, but are small and hard to seal in my experience. If you are serious, check out the connector at the below link. I have one of these and they are great. The only thing is that it is meant to connect to large tubing. But, it is about 2 1/2" in diameter, so there is a large area that is used to seal the connector to the bag.

"Thru-Bag Vacuum Connector" http://www.fibreglast.com/showproducts-category-Vacuum%20Bagging%20Equipment-19.html

You might also consider leaving the glass overhang about an inch onto the mold flange and trimming after the wing is joined.

Michael

< Message edited by Mluvara -- 8/13/2004 7:52:22 AM >

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Post #: 29

RE: Seeker Wing Mold - 8/13/2004 4:49:44 PM

daven

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From: Andover, MN, USA
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A 48" quickee wing would be perfect for this.

As to the tips, I made a template out of cardboard and trimmed the shape into the rohacell. I cut the rohacell so that it overhung the mold shape by about 3/4" all the way around. At that point I just put it in the bag and let the suction pull it into the corners. 25 oz is quite a bit of suction, and it holds it in there good until the glue dries.

I do need to revise how I'm doing the Trailing Edge. In the future, I think I will sand the rohacell at the TE very thin before bagging it. I'm having a tricky time cleaning up the back edge, and am worried about a wavy TE when this is complete.

I did overhang the glass about 1" on the flange all the way around, but trimmed that off before taking the picture. What was neat, was pulling the glass off the front flange and seeing the paint actually stuck to the glass. Surface looked very good, even with the pva.

I would like to leave the glass untill after it is joined, but to do that, I will need to have the rohacell fit perfect, rather than overhang and trim like I've been doing. Like you mentioned, its definately an experiment.

Ailerons should be pretty easy Rob, I'll take some photos when I get there.

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Post #: 30

RE: Seeker Wing Mold - 8/13/2004 4:50:45 PM

PylonWorld

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From: Monroe, NC, USA
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Dave,

A quick way to make a bag seal that won't leak is to slit the seam of the bag about 1", insert the tube, and put tacky seal around the tube. squeeze it down and you will have a seal that won't leak at 25 inches of mercury.

Attached are a couple of photos. Please pardon the blurriness, but you can see enough to get a better idea of what I described.

This bag has been used at least 20 times and it's as tight as ever. When you do discard the bag, just remove the fitting.

In terms of expediting the process, you can use a T connector with valves on each side of the T. Then you can bag two pieces at once.

You can also build a "hot box". I built one out of pink foam and I can have a set of skins ready to join in 4-6 hours. You do have to be careful and not exceed the deflection temperature of the molds. Pictures and descriptions of my hot box are in the General Racing Discussion forum. I run my box at 95-100 degrees.

You're probably not far off on the 6 hours for a complete wing. Getting the materials together, handling, and cleanup adds a little time, but it is still a lot faster than wood/foam/covering.

Attachments

Click to see fullsize image.

Click for fullsize

Click to see fullsize image.

Click for fullsize

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Post #: 31

RE: Seeker Wing Mold - 8/13/2004 5:06:04 PM

daven

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From: Andover, MN, USA
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I will check the fitting Michael mentioned, and if all else fails cut the slit and use sticky tape. I have a roll, but have never used it. Could I just use the sticky tape around the fitting I already have installed? I think that would work, and I wouldn't have to worry about sealing the hole from the fitting.

The vacumn pump I'm using has three outlets with shut offs on each one. I can run three bags (or more with T-fittings), but wanted to do them seperately to make sure I had a good plan on how the process would work. Also, the bag (tube) I'm using is 36" wide, so I can put both halves into the same bag. Jerry B built the vacumm I'm using, and I'm betting it can pull quite a bit more than 25 oz. Now if I can just get it to stop blowing GFI outlet breakers.

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Post #: 32

RE: Seeker Wing Mold - 8/13/2004 6:17:16 PM

PylonWorld

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From: Monroe, NC, USA
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quote:

ORIGINAL: daven
...

Could I just use the sticky tape around the fitting I already have installed? I think that would work, and I wouldn't have to worry about sealing the hole from the fitting.

...

Now if I can just get it to stop blowing GFI outlet breakers.

I started to suggest that, but the sticky tape is really sticky. Your fitting might be forever attached to the bag. You can take the fitting out, run a tube through the hole, put sticky tape around it, and use a patch of bag material to close the backside and keep the sticky tape from sticking to the breather.

Now that must be one heck of a vacuum pump.

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Post #: 33

RE: Seeker Wing Mold - 8/13/2004 7:15:51 PM

daven

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I'll give it a shot. I'll put a picture of the vacumn up later. It was built from a scavanged air conditioner that someone left at the field. I think its fitting its used to make wings

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Post #: 34

RE: Seeker Wing Mold - 8/13/2004 10:38:00 PM

DHG

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Dave, Gary, anyone else --

I was just on the Aerospace Composites site and noted that they offer both Peel-Ply and something called "perforated release film". Both, apparently, work the same way -- that is, you lay the material over your wet resin/cloth/Rohacell/wood/whatever, then put a disposable, absorbent layer on top of that to wick away the excess resin while it cures.

They say the perforated release film is easier to peel away when the epoxy has cured, but that the surface it leaves behind is not as "bondable" as the surface left by the Peel-Ply. Obviously, if you're doing a clamshell wing like Dave's, you're going to want to stick spars & stuff to the inside of the skins, so "bondable" would be a plus. On the other hand, it should be easy enough to rough up the points of contact with sandpaper (thus ensuring a good bond) even if the release film leaves a glossy finish. Any thoughts on this?

Thx
D.

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Post #: 35

RE: Seeker Wing Mold - 8/14/2004 1:23:02 AM

daven

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I used the perforated peal ply from Aerospace. It worked well, didn't know that it was un-bondable.

I will make sure I scuff it up, before putting in the internals.

It worked great.

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Post #: 36

RE: Seeker Wing Mold - 8/14/2004 3:53:40 AM

Mluvara

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The regular peel ply works really well. It looks like fiberglass cloth, but is actually a fabric like Dacron. It's basically a barrier that lets resin through to the breather which soaks up the resin. After awhile, you'll find out what the right amount of resin to put on the cloth is and the peel ply will pull off easily. My first composite wings were really heavy and I overdid the resin. If you are not using peel ply, then you will need to scuff the area where you are bonding to, otherwise you have a waxy surface to glue to.

I use the 1.8 or 2.7oz peel ply from aircraft spruce. http://www.aircraftspruce.com/catalog/cmpages/peelply.php If you are doing high tech layups (curing in an oven, etc, some of the composites stores have many designed for high temps.

Michael

< Message edited by Mluvara -- 8/13/2004 7:54:05 PM >

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Post #: 37

RE: Seeker Wing Mold - 8/15/2004 8:50:54 PM

daven

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From: Andover, MN, USA
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I sanded the rohacell down at the TE so that it was quite thin, almost to the glass layer.

I drew a line on the rohacell where the aileron torque rods will be.

Attachments

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Click for fullsize

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Dave Norman

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Post #: 38

RE: Seeker Wing Mold - 8/15/2004 8:54:07 PM