diggs_74

I'm in the final stages on a quickie V-tail plug and I've realised that the TE needs to be thinner, by a lot.. I'm not too worried about hacking into the plug to make it thinner but how the heck do you get the parting plate in center when your TE is only, say 1/32" thick?? If anyone has any tips on how to do this it would be much appreciated.. I haven't changed the plug yet so if I can't find a way to make the mold then it'll just have to be what it is..

Thanks in advance...

Ed Smith

I will attempt to explain how to do it.

With a regular mold the two halves would have a flange all round the tail profile which is the parting line. For a knife edge trailing edge do not have a flange along the trailing edge of the mold that is on the part line. The flange along the trailing edge should be 90deg. to the part line. The tail airfoil blends out to no step at the trailing edge. When the mold closes the trailing edges of the top and bottom molds come together kind of like two knife edges.

It may be too late now but when the mold is made the part line/flange goes around the tips and the leading edge. The plug trailing edge is pushed up against a square block that will give say a 3/4" deep flange at 90deg to the airfoil centre line. This method also results in a very stiff mold.

If I was not clear please ask more questions.

Ed S

diggs_74

Thanks Ed, very much.. I'm hoping to get to it this weekend sometime.. I'll try and post some pics when I get that far.. Still need to finish up the plug and if it doesn't get above 0F it takes along time for the primer to dry

Randy Etken

My Feedback: (10)

Ed clear as mud, please draw a picture.
Thanks.

Ed Smith

I have a drawing in Autocad format (dwg) how do I load it to the Forum?

Ed S

diggs_74

Probably the easiest way is to paste/import it to MS Paint or something like that.. That would put it in a format that could be posted.. Other wise Ed, you can email it to me and I can covert it to a JPEG... [email protected]

Troy-RCU

My Feedback: (1)

With drawing view on screen: Hit [control] & [printscreen] buttons, open up a new file in any photo or paint program with the document size about 640X480 pixels, Edit,Paste, and save as a jpeg. Then upload it from the Post Reply screen here on RCU. Voila!

Ed Smith

If it works here it is.

Thanks for the help. I have also sent Lee a copy for him to upload.

Ed S

Ed Smith

Now that I know how to do it here is an additional section view of the mold .

Ed

daven

My Feedback: (1)

That makes sense, thanks for the pictures. Much easier than trying to line up a parting board on the then TE off a V-tail;.

Randy Etken

My Feedback: (10)

Thanks Ed.

diggs_74

I didn't think about a screen shot... Oh well, here is the DWG that Ed sent..

It seems to have worked pretty well.. I built a new parting plate last night and it only took me maybe an hour to complete.. Thanks again Ed..

GR7Racer

How do you key the trailing edge with this method, and how do you clamp the mold halves together at the trailing edge?

Thanks,

KennyMac

Ed Smith

I am not quite sure what you mean by keying the trailing edge.

The parting flange on the tips and leading edge 0of the mold will have location pins as usual. These will align the two mold halves. When the mold is closed there will be some excess material hanging out of the trailing edge. This excess will be pinched as the mold is closed and clamped. To clamp along the trailing edge just use some "C" clamps as many as is necessary. If the 90deg flange along the railing edge is made robust enough it will prevent the mold from bowing and the result will be a sharp straight trailing edge when the excess is trimmed off. The trailing edge flange also provides an accurate straight surface to trim the excess material to befor the mold is opened.

Ed S

diggs_74

Well, here is my tail mold.. Still some clean up/polishing to do but other than that it turned out pretty well.. Thanks for the tip Ed...

daven

My Feedback: (1)

I really like your sippy cup in the first picture. I'd say that must be a Wisconsin thing, but I live here now

diggs_74

Yes that is my prefered dispensing apperatice for the whiskey of choice Actually, the boy was "helping" me and left it there..

Oh, here is the next part of the project, the fuse... Just finished it up during lunch..

Ed Smith

Hi Lee,

What is the purpose of the box like structure on the wing saddle?

Ed S

diggs_74

That is where I was going to have the hole to get inside the mold once the halves are joined.. I wasn't sure how else to do it other than that..

Ed Smith

Hi Lee,

This is not a criticism of your method. The first Quicky fuselage mold I made I left the whole wing saddle area open. There was a flange along the sides of course. The theory being the bigger hole the better and easier to reach inside. May later fuselage mold is three sided (Bathtub). The seam is along the bottom corner of the fuselage. I used a detachable front end, this made it much easier to get the fuselage out of the mold. The wing hole was just as large.

I like to see other peoples methods, this way I learn.

Ed S

diggs_74

Oh, I see how that works.. I could still do that by just cutting the front off the parting board and making a plate/flange for the firewall.. That would also remove the seam running thru the middle of it as well.. I guess I'll have to ponder that.. I've got a little time to think it over as the fuse plug still needs some finishing touches..

CRG

My Feedback: (3)

Looks really nice Lee. Which tooling resin are you using?

Craig.

diggs_74

I don't remember the brand right off the top of my head but I got from Aerospace Composites.. Seems to work well and polishes up real nice..

Ed Smith

It is not necessary to use a specific "Tooling Resin" as the gel coat. For my molds I use the same epoxy resin that will be used for the mold build up and the parts.

I make a gel coat by adding to the resin some Cab-O-Sil, to make it a bit thicker to prevent it from running on vertical surfaces and some carbon powder for a hard black finish.

Ed S

diggs_74

I pulled my first tail this morning.. Turned ok for the first try I guess.. The TE turned out really well, nice and sharp (thanks Ed..) My only worry is if I did the hinge line correctly.. If not, I'll have to cut it open and redo it..