fledermaus

My gently kit-bashed SIG 4-Star 60 is now complete, and I gotta show her off.

She just needs a little adjusting for balance, the servos need to be zeroed and the radio system has to be calibrated, but that won't take much. Provided that the weather and my day job cooperate, I hope she can take her maiden flight this weekend.

The basic concept here was an open-cockpit racing/sport plane of the Golden Age of Aviation, so I went for more rounded lines than the stock 4*.

The fuselage front has been flared out starting from the wing trailing edge using layers of balsa, carved and sanded to shape, and of course the standard SIG "cheeks" have been cut off. The wings have had one bay removed, but then the tips have been built out to a rounded shape that restores 1/2 bay on each side. The stabilizer is stock but with balsa tips added. The fin and rudder have been reworked: the fin uses almost all the stock pieces but the top portion has been cut away, while the rudder is completely new. I made 3/8 balsa plywood (3 x 1/8, grain on the centre piece running lengthwise), and cut the new rudder from this.

She's covered with UltraCote in Deep Red, White and Black. I had a bit of trouble with bubbles where the covering was layered, and there are a few spots around the compound curves that I'm not completely happy with. Still, this is my first attempt at a patterned covering job so overall I'm satisfied with the outcome.

The pilot is a Williams Bros. Racing Pilot bust in 2 5/8 inch scale. I cut down the standard cockpit canopy to get the windscreen - too curved for a real "Golden Age" job but that's fine by me. The frame edge was stiffened using a strip of 1/8 balsa cut cross-grain and glued around the curve, after which it was given a coat of 0.75 oz glass cloth and Z-poxy.

The cowling is scratch-built, fibreglass laid up on a foam block more or less following instructions from Cafeenman's excellent Airfield Models website. I used one layer of SIG 1.5 oz cloth, two layers of automotive body repair glass tape (roughly 6 oz, comes in 4 inch width and is very cheap and convenient), and then another layer of 1.5 oz. Lots of sanding, a bit of bondo, lots of sanding, bit more bondo, some sanding, priming, more sanding, then two coats of UltraCote Deep Red spray paint, with a wet 400-grit sanding between. I should probably give it one more sanding with wet 600-grit and a final coat of paint - but I'm tired of building. Spring has come to the frozen north and its' time to fly!

Under the hood is a SuperTigre G-75, with a Bisson Pitts-style muffler.

So, without further ado, TAAA DAAA!

Phlip

Let me be the first to say ... GREAT JOB!! I've no doubt she'll fly as good as she looks!

Phil

Kmot

My Feedback: (24)

Wow!! That is an awesome job you did!! [sm=thumbup.gif]

Hareman

My Feedback: (1)

Great job on the cowl - but watch your engine temperature; it doesn't look like it has enough air passages for proper cooling.

AllTheGoodNamesAreTaken

My Feedback: (180)

Nice plane. And I thought my work area was messy... [sm=lol.gif]

andrew66

hey, where did u get the cowl? that plane is sweet! it looks like it was professionally designed, good job

fledermaus

Thanks for the kind words everyone. I'm pretty pumped about getting her in the air.

She balanced fine after just moving the battery around which is good because she weighs 8 lbs 6 oz and I don't want to add any more weight. Now, just need to set up the control throws and then off to the field!

Hareman: I don't think there will be a big problem with cooling because although you couldn't see it in the pix I posted, there is a big outlet on the bottom of the cowl. It should be more visible in the pictures below, taken before final sanding and painting. The two intakes are roughly 3.5 sq inches, and the combined area of the side and bottom vents is around 12 sq inches, so it should give a decent venturi effect.

jollyroger

My Feedback: (6)

Great looking 4*! Nice kit bash. I bashed mine to look like a German WW II fighter.
BTW what did you use to attach the windshield. It looks like some sort os molding. I have a Fly Baby model I'm trying to finnish and need to attach the windshield without mucking it up with RC 56.
I need some suggestions please.
Again great looking bash. Jollyroger

fledermaus

The windscreen is glued to the top decking with medium CA, after cutting away a thin strip of covering. Before applying the CA, I wiped a little bit of kicker on the wood and the bottom edge of the windscreen, and I used a VERY thin plastic tube on the CA bottle so that I applied only a very small amount of glue. There was no problem with fogging the clear plastic.

I then used (ahem!) black duct tape cut to 1/4" width to put a nice finish on it.

btoby

where did you find the cowl at?

Heath Man

Nice job! How funny, I'm just starting a 4* kit bash and was gonna do the exact same thing to the wing and tail feathers! You have any pics of your rounding method on the wingtips? Did you use solid block or frame it out? I'm thinking you used blocks. I'm kind of leaning toward laminating and curved end and then putting some ribs in to cut down on weight.

Great job,
Heath

fledermaus

btoby: I made the cowl myself from scratch. It is really easy to do a fibreglass layup, especially if you follow the guidelines at Cafeenman's [link=http://www.airfieldmodels.com]Airfield Models [/link] website.

fledermaus

Heath Man: the wingtips were built-up, but in retrospect I think it might be just as easy to do a foam carving job.

What I did was this:

First, the wings are shortened by 1 bay.

I laid out the plan view I wanted, which was actually the top half of the airfoil stretched to 50% of the bay width between wing ribs, and cut it from 1/8 plywood. I removed a lot of the middle in lightening holes.

The ply tips were CA'd along the chord line of the end rib.

Then, I made 1/8 balsa tip ribs for the rounded curve I wanted at the turbulator spar, and main and rear spars, above and below the ply. These were done by eye. I also glued balsa blocks to the trailing edge of the tip, and sanded to the desired contour.

I also made a 1/8 balsa rib running diagonally from the turbulator rib out to the edge.

Then, I cut notches in the ribs to put in stringers. There are three stringers, at the points where the curvature begins, and where it changes.

Ok, so that is one wingtip. As each step was finished, I made paper templates and transferred the outlines to the other wingtip so they stayed the same.

It was actually not difficult but it was a lot of fussy work, and I don't think the result is any better or much lighter than you'd get with a foam core. I think next time I do something like this I'll make the same 1/8 ply tip, but glue foam blocks top and bottom and carve them down to the shape. They can then be fibreglassed with 1/2 oz. cloth.

In the picture below, you can see the basic structure of the tips. Sorry, I never took a close-up. This picture was taken when only 1 of the 3 stringers was in place.