I didn't build my airplane, so there's parts of it I can't see and haven't seen, but I'm getting there. Until I've seen and evaluated it all, I'll fly conservatively. 2-3gs max. Mainly what I haven't seen are the center wing strut/fuselage attachment points that are covered.
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Corben Junior Ace Scratch Build.
- Thread starter Jim
- Start date
In my buddy's Great lakes, we do rolls, loops, hammerheads.... we almost never go over 3g's. 'Course, that's with 200 horses pulling you through, so maybe not a fair comparison, still...
But yeah, I get ya. Those wing and strut brackets are pretty important. When's the next re-cover?
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Likely not on my watch. We did a pretty big patch on the bottom of the fuselage to repair the damaged elevator bellcrank mounts, and the right wing section got re-covered about a year before I got it after an unfortunate excursion into standing corn due to a landing gear failure. Tailfeathers are in good shape, and the left wing is in good shape, so I'm not anticipating any more fabric work unless I break something significant. I'm not in an enclosed hangar, but I am under cover, so I'm only getting UV when I'm actively flying. I should be OK for the next 10 years, I think. I haven't done any aerobatic training beyond 3 turn spins, and I'm not inclined to try to teach myself, that just seems like a bad idea! Now, if the opportunity presents itself and the cards fall right, I'll do some, but I'm not actively pursuing it at the moment.
No real update, jus' an observation...
Cleaning up the C-85 cases so I can start the reassembly.
Ran across this on the bottom of both halves...
So apparently, this engine was built (cast) on line 5, in June of 1947. That makes this engine 78 yrs old and counting. How cool is that?
Cleaning up the C-85 cases so I can start the reassembly.
Ran across this on the bottom of both halves...
So apparently, this engine was built (cast) on line 5, in June of 1947. That makes this engine 78 yrs old and counting. How cool is that?
Always fun to run across folks on different platforms/pages. The Small Continental group is a fixture in my FB feed.No real update, jus' an observation...
Cleaning up the C-85 cases so I can start the reassembly.
View attachment 360993
Ran across this on the bottom of both halves...
View attachment 360994
So apparently, this engine was built (cast) on line 5, in June of 1947. That makes this engine 78 yrs old and counting. How cool is that?
It is. I only joined about 3-4 mo ago. So far they seem a nice bunch.
Cases are cleaned up, next is checking crank and cam clearances.
Crankshaft:
Front main clearance=............ .004" (min is .0035", max is .006" for all 3)
Center main=............................. .0035"
Rear main=.................................. .004"
End (thrust) clearance=.......... .008" (min is .004" max .025"
Camshaft:
Front=........................................... .004" (min is .001" max .005")
Center=........................................ .004"
Rear=............................................ .003"
Close enough for me.
Crankshaft:
Front main clearance=............ .004" (min is .0035", max is .006" for all 3)
Center main=............................. .0035"
Rear main=.................................. .004"
End (thrust) clearance=.......... .008" (min is .004" max .025"
Camshaft:
Front=........................................... .004" (min is .001" max .005")
Center=........................................ .004"
Rear=............................................ .003"
Close enough for me.
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Cases are cleaned up, next is checking crank and cam clearances.
Crankshaft:
Front main clearance=............ .004" (min is .0035", max is .006" for all 3)
Center main=............................. .0035"
Rear main=.................................. .004"
End (thrust) clearance=.......... .008" (min is .004" max .025"
Camshaft:
Front=........................................... .004" (min is .001" max .005")
Center=........................................ .004"
Rear=............................................ .003"
Close enough for me.
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View attachment 361055
View attachment 361056
View attachment 361057
I’ve never seen that technique for checking crankshaft clearances, that’s interesting!
Plastigauge. Stick it on the cam and crank journals and torque the cases. The plastigauge gets squeezed... measure how much it got flattened. By far the easiest way to check clearances.I’ve never seen that technique for checking crankshaft clearances, that’s interesting!
Please forgive a digression. I'm familiar with the plastigauge method for measuring clearances and it puts me in mind of a measurement that used to be made in the days of really big guns on battleships. The used to make 15" guns and even 18". Those things were massive - barrel weighed 100 tons and a 15" shell weighs nearly a ton. The gunners would measure the pressure generated in the breech by loading a shell, charges of cordite propellant and finally a copper disc of measured thickness. The gun was fired, breech opened, copper disc removed and thickness re-measured. Obviously, how much thinner it was gave an index on the pressure generated. I mean, just Wow!
Just caught up with this; bloody interesting build I must say. Good on ya Jim.
Out with the old....
Mailman just popped by. Some bling for the little connie.
Mailman just popped by. Some bling for the little connie.
When your job was keeping a 28 cylinder boosted engine with 2 or more magnetos, 56 spark plugs and and an electric or hydraulically controlled propeller in top tune, working on post war automotive tech must have seemed utterly primitive.
I'm just curious if it'll have an M61 Vulcan mounted somewhere.
If you pointed it aft, it'd make a pretty decent afterburner...I'm just curious if it'll have an M61 Vulcan mounted somewhere.
Lifters.... tappets... whatever.
The wee connie uses hydraulic lifters. The manual calls for disassembly, cleaning and testing during buildup. Since this engine never ran the last time it was assembled, I almost skipped doing that.... almost. Glad I decided to take 'em apart, as 5 of the 8 were seized solid. 40+ yr old assembly lube has become a glue. Let 'em soak in the parts washer for a day, then alternated between tapping them on a piece of wood until I got some movement, then pushing 'em back together. It worked. Tedious as all hell, but they finally gave up.
Everything properly cleaned, you test 'em by soaking both parts of the lifter valve in oil and pushing 'em back together. They should give a good seal so that when you compress the piston part in the valve body and let go, the piston should shoot out of the body.... all do . Then you reinsert the piston, squeeze it down and push a toothpick in the small tube end that contains the check ball. Soon as the toothpick touches the ball, pressure is released and the whole thing collapses.... they do.
All cleaned up, tested and reinserted it their respective lifter holes.
The masking tape is on there to prevent 'em falling back out when I put the two case halves back together.
This all took much longer that I figured it would... was well past midnight when I quit.
Next up will be cleaning and measuring the con rods. Once they're done, I can reacquaint the two halves with each other.
I'm trying to build the Ace as cheaply as possible, but sometimes common sense has to rule the day. I splurged yesterday and ordered $70 worth of nuts, bolts and washers to put the two halves together. When there's nothing between your ass and the ground but 3000 ft of air, it'll be comforting to know it's new hardware holding things together... 'eh?
The wee connie uses hydraulic lifters. The manual calls for disassembly, cleaning and testing during buildup. Since this engine never ran the last time it was assembled, I almost skipped doing that.... almost. Glad I decided to take 'em apart, as 5 of the 8 were seized solid. 40+ yr old assembly lube has become a glue. Let 'em soak in the parts washer for a day, then alternated between tapping them on a piece of wood until I got some movement, then pushing 'em back together. It worked. Tedious as all hell, but they finally gave up.
Everything properly cleaned, you test 'em by soaking both parts of the lifter valve in oil and pushing 'em back together. They should give a good seal so that when you compress the piston part in the valve body and let go, the piston should shoot out of the body.... all do . Then you reinsert the piston, squeeze it down and push a toothpick in the small tube end that contains the check ball. Soon as the toothpick touches the ball, pressure is released and the whole thing collapses.... they do.
All cleaned up, tested and reinserted it their respective lifter holes.
The masking tape is on there to prevent 'em falling back out when I put the two case halves back together.
This all took much longer that I figured it would... was well past midnight when I quit.
Next up will be cleaning and measuring the con rods. Once they're done, I can reacquaint the two halves with each other.
I'm trying to build the Ace as cheaply as possible, but sometimes common sense has to rule the day. I splurged yesterday and ordered $70 worth of nuts, bolts and washers to put the two halves together. When there's nothing between your ass and the ground but 3000 ft of air, it'll be comforting to know it's new hardware holding things together... 'eh?
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When it comes to aircraft hardware, I have been very blessed. I learned to fly at a flying club on an Army installation. Our mechanic was an old, cranky guy that wrenched on P-38's during the war. I was young and dumb and never darkened the door to his shop (dumb, dumb, dumb!) When Govt. support for the club went away (new post commander who preferred golf) and they took away our airplanes, we moved to a nearby airport to start over, and several of the members appear to have "liberated" quite a bit of old Bill's inventory of aircraft hardware and tools (I expect the tools were gifted, Bill was in his 80's at the time, and about done). Anyway, all this stuff ended up in the hangar of one of the members who was also an A&P, since deceased, which the flying club now occupies. My airplane is right across the taxiway, and given my newfound retirement status (and need for aircraft hardware), I've been slowly inventorying the stash. It's impressive. I've even come across tools that I have no idea what they are for, even after studying homebuilder tool catalogs for 30 years. Know what these are? I think they are making up fuel or hydraulic lines. The calipers are for scale ...
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Here's what $70 worth of aircraft quality hardware looks like.
Not bad really. I suspect a trip to Ace Hardware for equivalent SAE hardware would be more expensive.
Not bad really. I suspect a trip to Ace Hardware for equivalent SAE hardware would be more expensive.
