[Caygeon Flyer]

Sorry Guys.

I had some significant life events which took me away from this model for a while. I am back at it now and will post some pictures soon.

Caygeon Flyer

[roscoe]

Glad to see you back Peter. Happy New Year.

[Sparkfarmer]

If I made anything as amazing as this model I would name it, place it in a vacuum chamber, and start a religion based on it.

[Caygeon Flyer]

Thanks Sparkfarmer. I will need a lot of blessing from the model airplane dieties when I get up the nerve to fly it!

Caygeon Flyer.

Originally Posted by Sparkfarmer

If I made anything as amazing as this model I would name it, place it in a vacuum chamber, and start a religion based on it.

[Caygeon Flyer]

Aileron Mass Balance

I have just completed the aileron mass balance which is the last step on the wing build before the rivets. The support is a slightly flattened 5/32 brass tube, and the weight was carved form a piece of 5/16” dowel.

[Caygeon Flyer]

Control Surface Corrugations:

The full scale Beaver has corrugated aluminum on both sides of the rudder, both surfaces of the elevator and on the bottom of the flaps and ailerons. They are all the same: corrugations at 3” centres, about 3/8” high, 3/8” wide at the bottom, tapered to about 1/8” at the top, and rounded. On the model this worked out to a spacing of 0.540” and a height of 0.068”.
Trying to replicate these caused a lot of head scratching. These would obviously be very fine feature, but they needed to be about the right spacing to look good, and of course parallel to each other. Trying to glue on individual bits to simulate the ridges seemed too daunting. I tried scribing ridges into thin aluminum manually, but got inconsistent results. A friend suggested building a machine to make the crimps, probably the same way that they make the full scale ones, but I had neither the knowledge of the tools to make such a device.
My solution was to mould them. I obtained a piece of ¼” aluminum plate and a machinist friend cut shallow slots into it at the right spacing. He was able to shape his cutting tool so that the slots had the correct profile. It was then a theoretically simple matter to cast thin sheets of material to replicate the aluminum sheeting on the full scale Beaver. I said theoretically because it actually took a fair number of rejects before I got the technique to work properly.
In the end I was casting the sheets with polyurethane casting resin. I embedded a sheet of ¾ oz. glass fibre into each one as it set, to give the part a little strength. Initially I used Por-A-Kast resin, which was tricky, as it starts setting in 90 seconds. Barely enough time to make sure that all the bubbles were out. Later, I used a slowed reacting clear Alumilite resin.
The finished sheets were cut to shape and glued to the model with 30 min. epoxy.

In the photos below, you can see the mould, taped off to make an aileron skin, then a sample piece of finished skin. The next photo shows the skin attached to the rudder before priming. The trim tab hinge is a piece of styrene tube notched with a hobby saw. The finished product on an aileron can be seen on the previous post (#24), and the finished tail surfaces in the next post.

[Caygeon Flyer]

Tail Surface Corrugations:

[mrrandyman]

Very nice work indeed.
It's good to see someone take the time to do justice to thier projects.

[alex sorensen]

Of course it is a little late now,But I am in the thinking stage of a Twin Otter 8 ft ws,with the same detail.Would thin gauge aluminum sheet work,and simply press,using a forming tool of the right dimension?Like a piece of flat bar steel,filed to the right curve radius and approximate length.Give it a love tap,or clamp it down to push it into the sheet aluminum? Ultimately,a cnc with a v groove,cutting a piece of arborite to make a mold,then pouring resin,like quick cast polyester on fine poly cloth would make a very professional sheet.Alex

[alex sorensen]

Having used Freemans quick cast`,you get about 10 minutes,of pouring time,and part it out in 40 mins.If you use epoxy,you can be as slow as 1 1/2 hours before it sets.Another method,of you have a metal mould,is to heat it to 140*,then use hot glue,heated till liquid and pour it on Have a strip of 1/16 ply ready to back it up with weights.It copies detail amazingly well.Alex