Author Topic: Chipmunk finally finished (Read 4162 times)

Tim Stagg · « **on:** March 28, 2014, 07:48:06 PM »

I have wanted to build a Sig chipmunk for the last 30 years and I finally decided to do it. I had been told the kits had pretty crappy wood and it did not disappoint, but you have to start somewhere. I molded a carbon fiber cowl from the plastic one supplied, came out pretty nice, replaced most of the sheeting and built up the horizontal and vertical stabs to save weight. I also built up the wheel plants and plan on glassing them.

Just a few minor changes: made equal wing panels, enlarge stab slightly and lengthened fuse slightly.

Just an example of how heavy the ribs where, I opened up the back end with a dremel tool....see pictures, that alone saved a 1/2 ounce, the wood hard as a rock. Another funny item is some parts where die mashed...others laser cut.... and they did not match the plans. Nothing like buying $ 50 in wood to replace wood you bought in the kit

Oh well, I wanted a chip

This will be an electric with an eflite 15 and 4S battery TBD on the size.

Here it is so far in the bare bones, will be silkspan and dope to the scheme on the box. That scheme makes the airplane in my opinion. Hopefully will be done by Brodak

Brad Smith · « **Reply #1 on:** March 28, 2014, 08:00:11 PM »

when you going to start covering and paint?
looks real nice so far.

Tim Stagg · « **Reply #2 on:** March 28, 2014, 09:30:19 PM »

This weekend hopefully, the weather is not going to be good for anything else.

Curare · « **Reply #3 on:** March 30, 2014, 03:34:23 AM »

Tim, that's a nice looking Chippy!

I'm currently buidling one and like you, I had the idea of knocking out a composite cowl for mine. Looks like you beat me to the punchline!

Did you make a mould of the cowling? Can you produce... another?

Tim Stagg · « **Reply #4 on:** March 30, 2014, 02:06:10 PM »

Greg,

I used the inside of each plastic cowl half provided in the kit, worked great, I left it about a 1/16 higher than the plastic halves and the joined them with a little fiberglass strip on the inside. I wasn't sure the plastic halves would work very well, but decided to try and it worked great. I have been following your build as well, looks great, if I had to do it over again I might have gone the foam wing route as well.

Tim

Curare · « **Reply #5 on:** March 30, 2014, 05:51:34 PM »

Tim, thanks for the compliments, I was wondering if you might be able to shed a little more detail on how you moulded the cowling.

Did you put the cowl together and then mould the whole thing in one? I take it you used the inside of the cowl for moulding? Also what release agent did you use on it?

Sorry for the barrage of questions, I'm going to be glassing the wings tonight, so if I can get the mould together I may as well do that while I have everything out.

Tim Stagg · « **Reply #6 on:** March 30, 2014, 06:44:59 PM »

Greg,

Not a problem and I am not an expert at molding stuff so this really was pretty easy. I used the plastic cowls in halves, greased them with Collinites Mold release that I got from a local boat builder....but I think something as simple as cooking grease will work. I use West System Epoxy and started with one layer of 3/4 oz fiberglass cloth, than put in a layer of about 5-7 oz carbon cloth....not sure, I was given a bunch of scraps by the same boat builder. Let that dry and then pulled from the halves....trimmed to fit and then assembled into the complete cowl.

That's it, pretty easy and it came out half the weight of the plastic shells.

Curare · « **Reply #7 on:** March 30, 2014, 06:52:18 PM »

Tim, sounds like what I was thinking exactly! I'll give it a shot, and at worst, I still should have the ABS or whatever it is part to use even if I screw up the cowl completely!

wwwarbird · « **Reply #8 on:** March 30, 2014, 08:01:10 PM »

Looks great Tim, I like that carbon cowl too.

Tim Stagg · « **Reply #9 on:** March 31, 2014, 09:05:44 AM »

Greg,

That was my plan exactly, and I still have the plastic cowl if I need to do it again, did not harm it at all

Curare · « **Reply #10 on:** March 31, 2014, 11:22:24 PM »

hehe, well sometimes no harm isn't always no foul, I decided to get 'smart' and tape the cowling together and see if could knock out a one peice product.

Dumb dumb dumb! It's impossible to get enough resin into the corners without a kinked brush (which I didn't have), and so ended up with huge dry spots, and what's worse is that all the resin collected where I DIDN'T want it and the part ended up as heavy as the ABS cowls.

I think I'll try again with two halves!

Tim Stagg · « **Reply #11 on:** April 01, 2014, 03:21:17 PM »

I like to refer to those kinds of things as learning experiences. I have tried to do a different cowl in one piece, it was extremely hard to pull out of the mold....almost to the point of destroying the nice carbon cowl.

I thought better of doing it that way this time

Bud Morrison · « **Reply #12 on:** May 11, 2014, 06:45:54 PM »

Any more progress on this I have on in box I am planning on electric. You didn't happen to make any extra carbon cowls did ya ?

Paul Taylor · « **Reply #13 on:** May 12, 2014, 06:44:38 PM »

Looks great Tim.
Makes me want to pull my Chip off the wall and refurbish / convert it.

Eric Viglione · « **Reply #14 on:** May 12, 2014, 07:17:28 PM »

Looks like another of your typical great jobs Tim. I've always had a soft spot for the Chip, and yes, with the defacto starburst paintjob. How are you going to tart this one up? Pennzoil type scheme or ?

EricV

Tim Stagg · « **Reply #15 on:** May 13, 2014, 09:43:23 PM »

Eric,

I too have always had soft spot for the red white and blue scheme. I flew the chip in primer last night....I have some work to do to find the right prop.....I think it will be a APC 12/6 cut down to 10.5 or 11 but it likes the 6 pitch.

The plane weighs 47 oz currently with battery, not sure I can paint and clear with 3 oz's but I am going to try.

Traveling this week but will post pictures of current state as soon as I can. I was trying to finish for Brodak but will not make it due to work schedule. I still may fly it in nostalgia 30 in primer for this year.......it just has such nice lines.

Curare · « **Reply #16 on:** May 13, 2014, 10:19:40 PM »

Tim, looks like we're on the home stretch together, Mine's also in primer

Tim Stagg · « **Reply #17 on:** May 30, 2014, 08:18:27 AM »

The clear was shot last night, had a few ink lines that bled.... but overall, not too bad.....anyway it is done. Trimming flights will most likely occur at Brodak. Not sure how much weight I put on it, I will weight once I get everything back in it. My guess is low 50's with battery but that is just a guess at this point. Might have gotten a little heavy handed on the gun last night.

BUT IT IS DONE!!!!!!!!!!!!!!!!!!!!!.....so tired of masking

Tim Stagg · « **Reply #18 on:** May 30, 2014, 08:19:20 AM »

couple more pictures

john e. holliday · « **Reply #19 on:** May 30, 2014, 08:50:43 AM »

That is awesome.

Tim Stagg · « **Reply #20 on:** May 30, 2014, 12:44:50 PM »

Just weighed with battery, ready to fly 51.5 ounces.

1.5 more than I was shooting for...but not bad.

Bob Hunt · « **Reply #21 on:** May 30, 2014, 06:03:51 PM »

That's just classically beautiful, Tim! Very nice job indeed.

Bob Hunt

wwwarbird · « **Reply #22 on:** May 30, 2014, 06:30:22 PM »

That's by far the nicest looking Sig Chipmunk I've ever seen, love that you stuck with the "correct" paint scheme and all the extra detail. Great job Tim!

Tim Stagg · « **Reply #23 on:** May 30, 2014, 06:37:31 PM »

Thanks for the nice comments guys.

Hopefully get to put some test flight in on Sunday

wwwarbird · « **Reply #24 on:** May 30, 2014, 06:41:36 PM »

Hey Tim,

I just spotted the nose of an unfinished profile plane in the extreme right of your first photo. What'cha got cookin' there?

Tim Stagg · « **Reply #25 on:** May 30, 2014, 08:36:43 PM »

Wow, that is a good eye.

That's a clown racer for Brodak, its in primer ready for paint. I think I may have some spare time tomorrow, maybe I will paint. Nothing to extravagant, as I mentioned I am tired of masking.

wwwarbird · « **Reply #26 on:** May 30, 2014, 10:02:40 PM »

Cool, hope we get some pics of that one too.

Curare · « **Reply #27 on:** June 02, 2014, 08:03:49 PM »

Jeez Tim, that's absolutely stunning!

It's actually made me depressed it's that good. How am I gonna even come close to that?

wwwarbird · « **Reply #28 on:** June 02, 2014, 09:05:02 PM »

Tim,

I've got a request. Next time you're ready to do some panel line shading, could we possibly get a "step by step" with photos in the Painting and Finishing section here? I'd really like to get a good look at how a pro does it.

Thanks!

Tim Stagg · « **Reply #29 on:** June 03, 2014, 06:38:38 AM »

Wayne,

Maybe I could figure out how to do a YouTube video of it. It is really not hard at all, just takes a little practice.

The biggest thing to remember is less is more, if you see the paint coming out of the airbrush, you probably have it coming out to heavy.

Maybe Sparky and I could collaborate on a video at Brodaks.

Tim Stagg · « **Reply #30 on:** June 03, 2014, 06:40:53 AM »

Thanks Greg,

Just mask a lot, and take your time.

I use common shelf paper as a masking tape for a lot of what I do.

There are no decals on the plane, I painted them all

wwwarbird · « **Reply #31 on:** June 03, 2014, 06:56:24 PM »

Quote from: Tim Stagg on June 03, 2014, 06:38:38 AM

Wayne,

It is really not hard at all, just takes a little practice.

The biggest thing to remember is less is more, if you see the paint coming out of the airbrush, you probably have it coming out to heavy.

Yep, that's all what I figured, I'd just like to get a first hand look at your technique.

Bud Morrison · « **Reply #32 on:** June 11, 2014, 08:39:53 PM »

Flies as good as it looks

Author Topic: Chipmunk finally finished (Read 4162 times)

Eric Viglione