LFG Roland C.II progress

[VNulk]

Thanks WF2, I look forward to meeting you. The C.II is 1/4 scale and fits comfortably in a 35 ft tractor trailer - not so well in a Honda Element.

Vern

[VNulk]

The spinner is made from fiberglass and 30 min. epoxy resin formed over a partially inflated balloon. The inflation was determined by measuring the approximate shape needed and in the case shown in the photos, worked out well and will be used as the flying spinner. Another will be fabricated once I have the scale prop made as the cutouts in the spinner are very different.

Each layer of glass is laid onto the balloon with a hole in the center of each to clear the balloon tie, and resin worked into the fibers. I did not cover the balloon with any material so the resin would adhere to the surface of the balloon to hold the shape while curing. Successive layers were rotated 45 deg from the previous to cross the fibers. I applied four layers in the copy shown and has proved to be adequate in the past.

A 1/4 in ply disk was mounted in a wood lathe and turned to the correct diameter and a bevel to accomodate the curvature of the spinner. After the resin had cured, the balloon was removed from the rough shape and edges of the fiberglass trimmed to an approximate diameter. The spinner was placed onto the wood disk while still in the lathe and centered by approximating the location, pressing a live-center onto the center of the spinner and spinning slowly to check for true turning. After just a few tries, the shape centered well on the disk and 2-56 self-tapping screws were set into the fiberglass and into the wood disk. Afterwards, the spinner was removed and the shaping of the cutouts for the prop began, and is not yet complete in the photos shown.

A similar spinner used on another plane was held onto the backplate by gluing 4 wood blocks on the backplate that each held a brass threaded insert so I could use 4 each 4-40 sockethead cap screws to hold the spinner onto the backplate. This method eliminated the need to work many small screws as in the scale version and I thought would be more reliable and safe, but I'm open to suggestions if someone else has an idea to consider.

[zoomzoom]

Interesting, this is very similar to the method I used to create the spinner for my Albatros DV. I used a blue foam plug with a wooden dowel glued into the center which was to become the central shaft. This dowel after being secured into the center of the plug was then inserted into the chuck of a power drill (I dont have a lathe) and then spun up and shaped to the right dimensions with very coarse sand paper, followed by lighter grades once close enough to final shape and for smoothing. Once it was finished and very smooth, I smeared the whole thing with a light coat of vaseline, and then iced it all over with about 1/4 of bondo. Before the bondo dried I cut off the center mandril and sat the spinner backside down on a glass surface so the bondo makes an even backside edge all the way round. Once dried, I popped the plug out from my new bondo female mold. In this mold I then did fiberglass layups just as you described Vern to make the final spinner. This all gets attached to a ply backplate just like yours, and I also used the "four block" method with blind nuts to secure the spinner, and its worked very well. Your balloon variation was quite creative though. I think I'd have made a real mess of that technique. Congrats on pulling it off!!

ZZ.

[VNulk]

Hey ZZ,

I have just been fortunate so far that the shapes I've needed were very shallow bowls that a balloon approximates. If another shape is needed, I would need to make a plug and since I was able to justify a new toy, the lathe, to the boss, I should be able to pull off a new spinner shape that a balloon can't help with.

A note: my first attempt at using the balloon, I first covered the balloon with plastic wrap thinking that I would need it to release the fiberglass, but since that resin can pull the plastic from the surface of the balloon, the curvature of the glass became distorted. Also, the 30 min epoxy I've used results in a semi-flexible bowl and others may find that a more robust epoxy product, perhaps from the marine product line, would yield a more rigid spinner, if desired.

As far as the threaded inserts go, I am a bit nervous about having small screws flying off when running the engine so I will continue to use the inserts and cap screws on the Roland spinner for flying.

[zoomzoom]

Sound thinking Vern. She's looking fabulous.....can't wait for lift off.

ZZ.

[VNulk]

ZZ,

Your reply reminded me of the first time I tried to make a fiberglass spinner using one of my mothers favorite plastic mixing bowls (she still stares at me when reminded). Like you, without like results, I smeared the inside of the bowl with vaseline thinking it would act as releasing agent. That bowl still protects a perfectly molded spinner blank (about $5 worth of commercial resin and fiberglass mat) in a dump somewhere. That was before "recycling" was in our vocabulary! After that, I stopped going to a kitchen other than my own for modelling tools and the like.

[VNulk]

The attached photos show the rivet installation and stitching. It would have been easier if I had ready access to slightly larger riviets but had to make do. the only local source is a craft store that has a good doll house section. The flange diameter is 3/32 in and once a hole is drilled, they were set onto the end of a brass wire tool, a drop of cyano was put on the barrel and set in place. Heavy waxed thread was threaded through each. The end result is acceptable and should add interest to the overall project.

[womenfly2]

Hey VNulk,

At the rate your going with her you should be flying it at Rhinebeck!

Looking really awesome. Love all the details, a few of the photo's she looks like the full size aircraft, not a model.

Cheers,
WF2

[Hannover]

[quote=VNulk;395192]
A note: my first attempt at using the balloon, I first covered the balloon with plastic wrap thinking that I would need it to release the fiberglass, but since that resin can pull the plastic from the surface of the balloon, the curvature of the glass became distorted. Also, the 30 min epoxy I've used results in a semi-flexible bowl and others may find that a more robust epoxy product, perhaps from the marine product line, would yield a more rigid spinner, if desired.
QUOTE]

What a great idea for making those type of spinners! I'm planning to build at model in the near future that could use one like that.

BTW, West Systems epoxy is great for doing layups, and it is very rigid, as well as sinding well. I get it from Aircraft Spruce and Specialties.

Jim

[VNulk]

Hi Jim,

I had a ready supply of the West systems epoxy for years but misplaced it during a move and never bought it again - I should do that. I know that marine supply stores in the northeast usually carry it. One great feature of the West products is that the pumps you can buy meter the mix very accurately and you don't have to guess at the proportions. I've also used their microballoons for a lightweight and easy-to-sand fills and another chopped fiber mix for heavy fills for robust joint re-inforcements.

Thanks for the note and a reminder to go get refills on the West epoxy.