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Building a Junior Ace

Tench745

Well-known member
#1
I haven't been very active here since I got back from FFEast. Part of this was burnout. I haven't been idle though.
I decided to one-up myself. I spent around 300 hours on my Spirit of St Louis model and came to the realization that rather than building one big model at 300 hours a year, I could devote that effort to building a real airplane. At 300 hours/year I could have a 1200hr aircraft built in 4 years. With that reasoning I started down the path toward homebuilding.
CorbenJrAcelanding.jpg

For various reasons I elected to build a Corben Junior Ace. This is the two seat variant of the Baby Ace. It's a wood wing and a welded steel fuselage covered in cloth. Often referred to as "rag and tube" construction.
I'm a theatrical carpenter by trade, so the wood work doesn't concern me too much, I just need to work to tighter tolerances than usual. I am a passable MIG welder, but for aircraft TIG or Oxy-fuel welding is preferred. I have an Ody-acetylene torch I'm practicing with here and there, but I'm no where near competent enough to weld the thin tubing in a fuselage yet. I plan on talking to a guy at my local EAA chapter about welding lessons.

I have a blog http://aviationcomingeventually.blogspot.com and a thread over on the EAA forums http://eaaforums.org/showthread.php?7943-Corben-Jr-ace-build to document my progress and process. Right now I'm 100 hours in and I have all 26 wing ribs nearly completed. The lower capstrips still need to be tapered for the trailing edge.
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foamtest

Toothpick glider kid
#4
I wish I could see your blog on my school laptop but everything is blocked. It took me two years to get the forums unblocked.

Either way I wish you luck with this build!
 

evranch

Well-known member
#8
Building an airplane is a dream of mine as well. I love when people share their build logs so I can see what goes into each of these, as I plan where I want to go myself.

Those ribs look amazingly light, this one might not be for me. I'm more for welding than finish carpentry!

You mention issues with cutting slots on your blog, I picked up one of those "oscillating tools" last year after a friend loaned me his. I always thought they were a gimmick, but they are a fantastic plunge cutter when something needs a slot in it.

Thanks for sharing and best of luck with the project!
 

Tench745

Well-known member
#9
Those ribs look amazingly light, this one might not be for me. I'm more for welding than finish carpentry!

You mention issues with cutting slots on your blog, I picked up one of those "oscillating tools" last year after a friend loaned me his. I always thought they were a gimmick, but they are a fantastic plunge cutter when something needs a slot in it.

Thanks for sharing and best of luck with the project!
They ribs are pretty light, about 180-190grams each depending on the rib. They go together just like a big balsa model. Cut to rough size and grind the angle to fit on a disc sander. (Mine are actually cut square as the gussets add the strength, not the bevels)
We've got one of those oscillating tools at work, I call it "the angry mosquito," but it does work well. Too much of a specialty thing to be worth the investment for me right now. There were definitely times it could have been useful though.
 

Tench745

Well-known member
#10
I haven't done much on this lately, but I did put in about 3 hours today adding filler strips between the wing ribs. I did a quick time lapse of the work but had the interval time too long so it's a really short video. I've included it anyway.
 
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Tench745

Well-known member
#12
Video three had me cleaning up the filler pieces between the ribs and putting varnish on the aileron.

I did a bit of work off camera before the next timelapse. Among other things I began fitting the wingtip bow and varnished the topside of the wing.

Today's work consisted of welding mounting tabs onto the wingtip bow, shaping the leading edge, and varnishing the underside of the wing.

I have to fix the trailing edge of rib 13 that the wingtip bow mounts to. I managed to crack it off early on in assembling the wing. Proper aircraft repairs will be done, just as soon as I can talk to my tech advisor about exactly which method I'm supposed to use.
 
#14
They ribs are pretty light, about 180-190grams each depending on the rib. They go together just like a big balsa model. Cut to rough size and grind the angle to fit on a disc sander. (Mine are actually cut square as the gussets add the strength, not the bevels)
We've got one of those oscillating tools at work, I call it "the angry mosquito," but it does work well. Too much of a specialty thing to be worth the investment for me right now. There were definitely times it could have been useful though.
You could probably use a router to start the cut
 

Tench745

Well-known member
#17
Both broken wing ribs have been replaced. The last one just got its first coat of varnish and I've ordered all the tubing I should need for the fuselage and tail. Snapped this picture while pulling the right wing back out to replace the broken tip rib.

It's really surreal to work on little bits and then finally step back and realize that somehow I have a pair of wings!
 

Tench745

Well-known member
#19
great looking wings, you need the homebuilt tag that states the pro's don't build to this quality.
Varnish? Why not clear 2 part something or is that just a generic name for your process? Are you using aerothane style or old fashioned dope?
I'm using the Randolf 2-part epoxy "varnish". I plan on covering with Stuarts System, so I don't need to use the epoxy system but it lasts and protects well. It's hard to filter through the noise of the internet to get reliable reviews of other systems. Rot sucks; I don't want to play that game with a wing. I'd rather do it once and do it right, even if the stuff is ridiculously expensive.
 

Piotrsko

Well-known member
#20
Love the randolph stuff. $$$$, Yeah but the Pacer still passed a punch test after 10 years outside so expensive is only once instead of cheap often.
Had the same issue with processes, too much chaff in the data. I ended up doing dope because that was the only thing my AI would sign me off for doing myself.