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May 05, 2019, 08:02 PM
A man with a plan
Balsaworkbench's Avatar
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On a lightweight plane the extra engine weight is noticeable. It's not a deal breaker, though.
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May 06, 2019, 12:31 AM
A man with a plan
Balsaworkbench's Avatar
Thread OP
I put the top sheeting on in the tail section. Then I installed the push rod tubes. The rods will be steel rod in nylon tube.

I used to get the 30" steel rods and nylon tubes at the local hobby store when I lived in the Kansas City suburbs. Now that I live in the boonies I've been using up the giant box of random push rods I bought from a guy getting out of the hobby almost 20 years ago. I'm scraping the bottom of the barrel, so it was time to order some rods and tubes from Du Bro. If I remember correctly, I bought these from a dealer on ebay. It's a 30 inch rod and a 30 inch nylon housing. Best push rod you can get for a 20 to 60 size plane. I suppose it doesn't matter that I don't live next to the store any more. The store is gone anyway.
May 06, 2019, 12:35 AM
A man with a plan
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I just noticed that I started this project on March 28th. These planes have spent a lot of time sitting untouched on the building table.
May 06, 2019, 08:46 AM
The runway used to be longer
Mad_Mike's Avatar
Build when the spirit takes you.

Mine took 54 days, since you're building 3 at once, you have until 06-Sep-2019 to do the maidens at that pace.

I have to say that the pics of 3 at once look very cool.
May 06, 2019, 09:02 AM
A man with a plan
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You'd think it would take a lot longer to build three, but it takes almost the same amount of time as one. I figured out that most of the time at the building table is spent on head-scratching, planning, or just thinking about some other random thing. Then once I'm ready to do something to the plane it doesn't take much time at all. With three planes I'm multiplying only that small portion of the time by three.

The photo reminds me of the old pictures of airplane factories taken during one of the world wars, except that their planes were a lot better looking.
May 24, 2019, 01:05 AM
A man with a plan
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After sitting neglected on the table for another long spell the Corkscrews made some progress. I guess it was two and a half weeks. I remember when I would start and finish a plane (or usually two of the same plane) in that time, and move on to the next one.

After about an hour of work the wings are framed up. The plan shows an open structure wing, but I generally prefer D Tube construction with sheeting from the spar forward, and cap strips on the ribs. I glued the bottom sheeting to the spars and trailing edges, marked the rib locations with a pen, pinned them to the table, and built the wing on top of them.

I'll see if I can keep this project moving along now, instead of leaving it idle for weeks at a time. It's hard to get interested in RC planes when it's always raining and too muddy to get to the flying site. We're supposed to get another two weeks of rain showers.
May 25, 2019, 12:34 AM
A man with a plan
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I put the top sheeting on tonight, and the bottom center section sheeting.
May 25, 2019, 11:28 AM
Registered User
Why did you blacken the fuel tank and engine compartment?

Also, can you share your thoughts on the D-tube wing structure on this plane VS the Miss Bikini structure?
May 25, 2019, 12:00 PM
A man with a plan
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Quote:
Originally Posted by Harjit
Why did you blacken the fuel tank and engine compartment?
Any color scheme I can think of would look better with a black engine compartment. And this way I don't have to try so hard to make it look good. It's sort of like a fat person wearing a black shirt to hide details.


Quote:
Originally Posted by Harjit

Also, can you share your thoughts on the D-tube wing structure on this plane VS the Miss Bikini structure?
The Miss Bikini plan shows a full depth 1/8" balsa sheet spar. This was a lot more common in the stone age when people were happy to hand pick their balsa and sit there cutting it all afternoon with a hobby knife or a broken razor blade. When I traced the parts for my laser kit I made 3/16" x 3/16" spar notches so the builder could use spruce or bass spars with 1/16" balsa shear webs, in the modern fashion. This is exactly the same as the Corkscrew wings I'm building now, so when I build the Miss Bikini wing this evening it will look just like the ones in the above photos. The only difference is that if you want a kit I'll cut the Corkscrew as shown on the plan or as shown in this build log (builder's choice), but in the case of the Miss Bikini the only choice is with 3/16 x 3/16 spar notches. I don't offer Miss Bikini wing parts as shown on the plan because I can't be certain that I'll have hard 1/8" sheet balsa suitable for spars, and the laser cutter doesn't like dense wood anyway.
May 25, 2019, 12:33 PM
Registered User
Makes sense and thank you for sharing.

Will you cut the shear webs on the laser cutter?

Are the cap strips decorative or functional? I was thinking with 1/16" ribs, they would be necessary but with 3/32", they may not but I don't have that much experience.
May 25, 2019, 01:55 PM
A man with a plan
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You're right. Cap strips serve a purpose with thinner ribs but are kind of superfluous structurally if your rib is thick enough to stand on its own. I like using them because I find that ribs tend to be subjected to sanding abuse, so it's easy to just throw a strip on there and give everything a nice finishing touch with the sanding block.

I don't generally cut shear webs on the laser cutter because I always have little pieces of sheet balsa left over. It's easy enough to cut rectangles out with a knife and a straight edge. It beats burning a full sheet of wood on such a mundane cutting job, and it's better than loading all the scraps one by one into the laser cutter. I make an exception for wings such as the Kaos, where an accurately engineered shear web can be used to set each rib in its proper place and orientation. But with these projects I'm just going to use the garbage that's already lying around.
May 27, 2019, 01:54 PM
Registered User
Quote:
Originally Posted by Balsaworkbench
My last post was a week ago, and I didn't work on the fuselages again until last night. I used a giant Sharpie marker to blacken the tank and engine compartment, then sealed the compartment under the fuel tank floor with epoxy, and epoxied the tank floor in place on all three.
Do you use 5 minute or 30 minute epoxy?

How did you thin it?

I imagine the trailing edges are square or rectangular in shape. Since they have to end up following the contour of the rib, do you sand them on the fixture before gluing the trailing edge sheet?
May 27, 2019, 03:23 PM
Registered User
Quote:
Originally Posted by Balsaworkbench
.

You're right. Cap strips serve a purpose with thinner ribs but are kind of superfluous structurally if your rib is thick enough to stand on its own. I like using them because I find that ribs tend to be subjected to sanding abuse, so it's easy to just throw a strip on there and give everything a nice finishing touch with the sanding block.
...
I've always used balsa capstrips glued onto exposed ribs.


While I agree that they likely are not necessary structurally - because, in my opinion, ribs are probably the least stressed parts of the wing, not because the rib thickness is fat - "theoretically", they impart an I-beam construction to the exposed ribs, which should give greater strength, at minimal additional weight and work.

In addition to "sanding abuse" of an almost completed wing, if one is using the "sandwich stack" method to generate wing ribs, and using the typical D-tube construction - with balsa sheeting between the leading edge and main spar - planning for a balsa capstrip - and a narrow, spanwise balsa strip at the trailing edge spar - means a continuous carving/sanding stroke from leading edge to trailing while the ribs are in the stack.


Also.... with D-tube and balsa capstrips, you can use "found" depron grocery store (produce and meat) tray material for ribs; the balsa sheeting of the foam ribs, using white/yellow wood glue, allows you to attach heat activated covering without damaging the foam ribs. At times I've used such salvaged foam material in .25 to .40 funfly planes as Dan Santich's Hots series and never lost such a constructed model due to such foam ribs, which, btw, are very easy/quick to carve to shape with a sharp razor type knife and a ply/arborite rib template on an individual rib basis.


Michael in Ontario, Canada
May 27, 2019, 04:33 PM
A man with a plan
Balsaworkbench's Avatar
Thread OP
Quote:
Originally Posted by Harjit
Do you use 5 minute or 30 minute epoxy?

How did you thin it?

I imagine the trailing edges are square or rectangular in shape. Since they have to end up following the contour of the rib, do you sand them on the fixture before gluing the trailing edge sheet?
I used 30 minute epoxy, mixed thoroughly and then thinned with a few drops of denatured alcohol.

The trailing edges were square sticks. I glued them in place on the wings, then sanded the taper. This is partly the kind of treatment I was referring to when I mentioned sanding abuse. I've gotten pretty good at sanding leading and trailing edges without destroying the ribs, but sometimes I might take a little bite out of a rib.

Incidentally, these wings were built on the table, held in place with pins during construction. I never use a wing jig when building flat bottom wings.
May 27, 2019, 04:37 PM
A man with a plan
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Quote:
Originally Posted by 2michaely
a continuous carving/sanding stroke from leading edge to trailing while the ribs are in the stack.

I used to cut ribs individually with a hobby knife, one at a time. It sounds crazy, but the ribs are pretty nice and it doesn't require any jigs, bolts, stacks, etc. Now I have the laser cutter, so if I'm trying to hide any kind of damage, it could only be what I did wrong during building.


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