SHORT SOLENT MARK IV – 2014 WINTER BUILD

piker · October 10, 2014, 08:36:12 PM

You ruined your best pair of panty hose?!!!

wollins · October 10, 2014, 09:15:38 PM

Never mind, I have more.

wollins · October 10, 2014, 11:18:16 PM

Ok so I've decided to lay out the steps I took, for my own future reference.

First off I decided that I had to make some tools, jigs if you will ... to get and keep the spinners symmetrical. The first I made was a shaping jig to cut the spinners from the block of foam to the shape I needed. The second was a couple of sanding jigs to maintain the shape of the spinners as I was sanding them.

Colin

wollins · October 10, 2014, 11:26:35 PM

The second thing I did was make the backplates from 1/16 ply by using a 1.5inch hole saw. Then I bolted the backplates on to the foam block, stuck them in the drill press and put my handy dandy shaping jig to work!

wollins · October 10, 2014, 11:35:45 PM

Next I had to create a release barrier between the foam and the actual material I was gonna be using to construct the spinner itself. I used cling wrap rubbed down with mold release for this. Stretched it over the "forms" and then coated it with a thin coating of epoxy. I then stretched the panty hose over the cling wrapped form for my first layer of the spinner itself.

Why panty hose? Well the conventional or more common material is to use fiberglass cloth but the panty hose conforms much better to the shape of the form that you're using. (in this case the foam cone) The only drawback of this is that the panty hose is very weak compared to FB, but I figured if I used enough layers I would get the strength I needed.

Colin

wollins · October 10, 2014, 11:43:49 PM

After that dried I then coated the panty hose with another thin coating of epoxy and laid down my second layer of panty hose over top to strengthen and add more rigidity to the spinner.

I then coated that with light weight filler to fill any imperfections in the structure. After that dried I then sanded them (with my sanding jig

) and sprayed them with high fill primer.

Colin

wollins · October 10, 2014, 11:50:28 PM

Next I sanded most of the high fill primer off to get them as smooth a finish as I could. I then installed my screws that I would use to attach the spinners to their backplates. Then I cut out my prop cutouts. The hardest part of this whole process was to get them all exactly the same shape and size. I think I did a pretty good job but you may (

) have noticed that the second spinner from the right (in the last pic) is a little more "pointed" than the rest which are more scale. That's the challenge of doing multiple spinners. At a casual glace on the plane it probably won't be noticeable but knowing myself I will probably do that one over to match the others.

The other challenge was that I also found the panty hose to be much weaker than I expected, even with two layers with epoxy in between. Without the backplates the spinner bottoms are VERY flexible ... so much so that I'm concerned that the bottoms of the spinners (in between the cutouts) may "splay" during high rpms. Therefore I've decided to reinforce that area by adding a one inch wide "ring" of fiber glass cloth to the inside circumference of the spinners. That should make it bullet proof.

Oh ... and I still have to add one last coating of lightweight spackle to fill some pin holes then they are ready to paint and balance.

Colin

wollins · October 19, 2014, 08:54:53 PM

Wow, nine days since my last post and I'm supposed to be building this thing!? Anyways, been busy with life ... finally started putting some glue to some sticks for the fuse. Plan is to just frame the two sides then put them aside and start the wing.

Colin

piker · October 19, 2014, 11:15:57 PM

Who's glasses? Is your Gramps helping you build?

wollins · October 19, 2014, 11:33:21 PM

Never mind ... I use a magnifying lamp as well as the glasses!!

I hope you use your glasses when you're cutting out my Morphine cores!

piker · October 20, 2014, 09:51:05 AM

I have two pairs in my workshop. I regular pair for generally seeing stuff, and a stronger pair for more detailed stuff.

Ugh! What are we going to do when we get old?!

Papa · October 20, 2014, 01:40:52 PM

Stop making irrelevant posts about age for a start!

Jack.

piker · October 20, 2014, 02:30:22 PM

What are YOU so sensitive about?

Papa · October 20, 2014, 03:37:12 PM

Snarkey Whippersnappers.

After reading that I do sound like my Dad.

LOL

Jack.

wollins · October 23, 2014, 07:37:28 PM

Ok so after putting in 38.5 hours so far (keeping track this time as per Graham's question and my own records.

) here's where I'm at. I was supposed to just frame up the sides and then start with the wing but I'm waiting on some stuff for the wing so decided to go ahead and at least get the fuse fully framed up.

As you saw in post #67 I started the process with one side but decided to try something new (to me at least) to get the other side exactly the same as the first side. With my CL-415 I had built both sides on the plan separately and consequently they did not come out exactly the same.

THIS time I wanted to try a trick I learned ... that is to put some paper (in my case parchment paper) on top of the first finished side and then build the other side on top of that, as opposed to on the plans.
All I had to do was tape the paper down really tightly and then rub it down over top of the frame slightly with pencil so as to bring out visual references as to where the edges of the original frame was.

It worked really well as you can see in the second pic. Came out exactly the same.

Colin