Corben Junior Ace Scratch Build.

[Jim]

This'll need some 'slpainin'....

All my life I've wanted to build my own airplane. It's an itch I jus' gotta scratch. Key words there are "my own." Without looking it up, I think there's 5 of 'em that I've built. None of 'em count. 4 of 'em were Renegade Falcon LS'. That was my job for a few yrs.

First though, they were "kits." We'd get a 20ft box of parts that contained the fuselage, wings and tail feathers. We would add the hardware, landing gear, avionics and engine, put all the pieces together and low and behold, there's a right smart little airplane.
Second, they weren't mine. They were built for customers and sold.

Don't get me wrong, I loved that job, and got to experience the thrill of taking an airplane that you built with your own two little hands, and taking it up on it's maiden flight. Both terrifying and exhilarating all at the same time.
Full disclosure, I was in the right seat as a flight test engineer and not as pilot in command. Still a thrill nonetheless.
At the end of the day though, I didn't build "my" airplane

When I lived just north of Seattle, I was building a little wood replica of a Pitts Special called a Ragwing Special. Again though, I was building it for someone else. I had the fuselage and wings almost done when the guy took a new job and moved out of state.... taking all my woodwork with him. I lost track of him after a few yrs and don't know if he ever got it finished... or it wound up being garage clutter.

That brings us to today. In one month I'll be 71. If not now, when?
Anyway, enough ramblin'...

I'm building a Corben Jr Ace. No kit, plans built. No customer, it'll be mine. I'll fill in the blanks as I go, but it's a classic steel tube and fabric build. Two seat, side by side, open cockpit taildragger that blazes it's way through the skies at a blistering 70-80mph.

Stay tuned.

6/20/25: Plan/drawing set............... $100
8/15/25 AC Spruce............................. $489 (wing hardware)
11/13/25 AC Spruce........................... $70 (Cont. engine hardware)
12/15/25 1 & 2 intake manifolds... $96
12/18/25 6 ea pistons (Ebay).........$200

 

[gggGary]

Ooh ooh ooh

 

[Downeaster]

This is gonna be fun!

 

[DogBunny]

Wow! No kit! Your energy level is inspiring.
(Which is what I said about your new workshop.)

 

[grouchie77]

What size engine? 350 small block Chevy?

440 Hemi?

....650 Yamaha twin?

 

[Jim]

Ace particulars.

It was designed in 1923 by Mr. Orland G. (Ace) Corben as an affordable homebuilt airplane. Ace is now thought of as the father of homebuilt aviation. The next year, 1924, Ace built a two seat version and called it the Junior Ace. In 1955, Mr. Paul Poberenzy, founder of the Experimental Aircraft Association, built a modified Baby Ace Model C as a three-part series in Mechanix Illustrated.

Here's the particulars of the Ace, copied from Wikipedia.
https://en.wikipedia.org/wiki/Ace_Baby_Ace

Ace Corben is in the Wisconsin Aviation Hall of Fame.
https://www.wahf.org/hall-of-fame/orland-corben/

So, with all that out of the way, the next post will document all the parts I already have on hand, and the work already in progress and/or completed.

It just occurred to me that I have drawings on the wall that were first inked 102 years ago... and hanging just above that is a Springfield smoothbore that's 150 years old. As a history buff, it don't get much better'n that!

 

[Jim]

What size engine? 350 small block Chevy?

440 Hemi?

....650 Yamaha twin?

I have a Continental C-85-8 that's currently in pieces for a rebuild. The 85 represents the horsepower. The engine is normally the most expensive part of a homebuilt. This one I picked up about 25yrs ago for a song. It'll take about $1k to bring it back to airworthy condition. That represents about $15k to $20k I won't have to spend.

 

[Mailman]

Very nice! Would I be way off in saying it reminds me of a Piper Cub? ( I know nothing about airplanes ) It does look like it would be very forgiving to fly.

 

[Jim]

Very similar to the Cub. Biggest differences are the Cub has an enclosed cockpit, unlike the Ace that's an open cockpit parasol type wing.
Same engine and same steel tube and fabric type construction. Performance is almost identical.... with the Ace performing slightly better.

I actually have some Cub parts that will be incorporated into this airplane.

 

[grouchie77]

I have a Continental C-85-8 that's currently in pieces for a rebuild. The 85 represents the horsepower. The engine is normally the most expensive part of a homebuilt. This one I picked up about 25yrs ago for a song. It'll take about $1k to bring it back to airworthy condition. That represents about $15k to $20k I won't have to spend.

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Do you have a test stand for when it's ready to run? Sure would love to hear it.

 

[WideAWAKE]

a bit of an outside questions…

If you were running two builds side by side, all things equal aside from the fact that one was a solid outside structure and the other was fabric, what would perform better?

 

[Jim]

Do you have a test stand for when it's ready to run? Sure would love to hear it.

I've got a small trailer when the time comes. I'll mount it to that. And yeah.... there'll be videos.

 

[Jim]

a bit of an outside questions…

If you were running two builds side by side, all things equal aside from the fact that one was a solid outside structure and the other was fabric, what would perform better?

Really wouldn't be any difference. Finished fabric is every bit as smooth as aluminum or any other painted material.

 

[MrBultaco]

This endeavor explains your new avatar...
Following with interest just like I do with ALL your other projects.

 

[Raymond]

Ditto. My friend Anthony has moved back to N Ireland with his family which means we don't see them quite as often - we're all going on hols together to Madeira in October. You might remember his Taylor Craft which I have been helping him with? It's moved on a lot since we were spraying wing ribs and he is hopeful of it being airborne next year. Similar engine to yours but can't remember exact model.

 

[Pat D]

Well, well. Pretty damn cool. I didn't build my Grega GN-1, but I have gotten very intimate with its construction. Continental C85, no electrics. Shortened Cub wings, Cub gear, based on the Pietenpol. Burned a few gallons this afternoon.

 

[Jim]

Nice!!
I've a set of Cub spars for this build. The Ace is also based on the Pietenpol.
Is you C85 a -8 or -12?

 

[Pat D]

Nice!!
I've a set of Cub spars for this build. The Ace is also based on the Pietenpol.
Is you C85 a -8 or -12?

It's a -12, just no accessories. Starter/generator openings are blocked off. That left Eisemann mag is now gone, coil went bad and they're no longer available. Just put a PowerUp (Slick rebuild) on it.

 

[46th Georgia]

I have a Continental C-85-8 that's currently in pieces for a rebuild. The 85 represents the horsepower. The engine is normally the most expensive part of a homebuilt. This one I picked up about 25yrs ago for a song. It'll take about $1k to bring it back to airworthy condition. That represents about $15k to $20k I won't have to spend.

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I know it's a dumb question, but why are aircraft engines so expensive?

 

[Pat D]

I know it's a dumb question, but why are aircraft engines so expensive?

Hehe- Jim's figures are actually a bargain as far as aviation powerplants these days. A couple factors. Economies of scale, just like aviation gasoline, there aren't very many of them compared to any other mode of internal combustion power. #2 is the certification process- the FAA is pretty concerned that certified aircraft components are of high quality and meet many very specific parameters. And other than a handful of mfgrs. that are producing specifically for the "experimental" market (again, a small market considered in scale), a lot of aviation powerplants aren't made any more. Our little Continental 4 cyls under 100 hp are the pinnacle of 1930's technology, and no one is making them any more. So, scarcity also contributes even if the components are not "certified" or were certified at one time. Product liability is a significant factor as well, juries have awarded vast sums to plaintiffs based on slick attorney presentations that in many cases blame the mfgr for poor decisions made by pilots/owners. A jury once ruled that the "taildragger" configuration (which basically won WW1 and WW2) was inherently flawed, another jury ruled that Piper aircraft was at fault when a pilot flew one of their products into a thunderstorm and it broke up in flight. You can't make this stuff up.