BETA Build: Nobi's Junkers SRF 1:48 scale

[rbeach84]

I am using Firefox and only certain cookies are trusted. But any object in an HTML that acts as a "download" link will work if it is 'triggered', just like the 'download' buttons in the Download section of the Forum. If the site script can provide a specified download target (such as "C:\") then it should go through. My Firefox is set to ask when downloading, but I suppose even that can be defeated... just better to be 'safe' than sorry. Perhaps my allowing Yahoo! domain sites to apply cookies is (as an example) a vulnerability that I need to address.

[rbeach84]

Originally Posted by Ron40

Robert,
To further strengthen the wing cut some 1/4" strips from card stock or
whatever paper thickness the model is printed on and install them lengthwise
along the spar. Thus making essentially an I Beam. This not only strengthens
the spar but also minimizes the chance that the spar will make a raised areas
when the wing skin is formed and closed up. Ron

I'll do that next time, trimming off top & bottom of the spar a thickness to accommodate a solid strip.

[Ron40]

Robert,
You do not need to trim off the upper or lower spar. The addition
of the strips is minimal and will not affect the closing of the wing
skin unless the paper thickness is too heavy. Ron

[Ron40]

Robert,
I forgot to add that you do not glue the I beam spar to
the upper or lower wing skins during assembly. It will
just float in the area. If you glue the spar to the skin
it will show through the paper and most likely affect the
wing skin closure. Ron

[rbeach84]

I have tended to apply glue to the top and botton of the spar. I will watch for the "float" issue. Makes sense since the root and tip are already secured to the skin... so the wing skin isn't going to shift around...

I haven't yet posted my latest pix, but I've attached the stabilizers to the tail (I added the extra reinforcement strip to the top, and with the small size of the horizontal tail parts it was a good thing I did trim the top a bit...) and completed the port wing & wingtip. RE: the spar work, I ended up having to trim the reinforcement strip aft of the spar because it interferred with the lateral placement of the skin - which had to be shifted forward a bit - but this didn't really effect anything, more of a test run than anything.)

So, hopefully I can get the latest posted soon, or at least get more done. The engine nacelles and pylons are "up" next and I plan on 'engineering' that internal brace for the pylon once I have all the pieces together for fitting purposes. I expect Deckape will probably start 'chiming in' soon once his build is underway, so we'll get it done.

[bagpiper]

Very nice build thread mate.
Appreciate your efforts putting this out here. Very nice indeed.

Cheers
Jim

[rbeach84]

Originally Posted by bagpiper

Very nice build thread mate.
Appreciate your efforts putting this out here. Very nice indeed.

Cheers
Jim

Jim, thank you for saying so, I think your GeeBee thread is very nice too.
A little off-topic, but I visited San Diego about a year ago and went by their museum. They are housing a beautiful recreation (not replica, in the usual sense) of the R1. Apparently, the heirs of original builders hold all the "paperwork" for the plane, and they allowed the recreation builder to construct the "new" R1 on two conditions:
1) that it be absolutely faithful to the original (construction methods, materials, engine, etc.)
and
2) it would never be flown!

I suppose after what happened to the flying replica (it crashed and killed the pilot), the Granville family didn't want to see the Brothers' design take any more lives! Still, one cool looking airplane... and a beautiful recreation of the beast there. I mean, hand hammered metal for the spats & cowling, wow!

Back to our regularly scheduled program.

[Ron40]

Robert,
The reason to not glue the spars to the wing skin is once
the glue dries completely it tends to absorb all the moisture
in the paper around it. It may not show now but will in a
couple of days of drying time. Ron

[rbeach84]

To continue, I want to detail the work on the tail stabilizers. This is a bit backwards in order, but the first image shows the starboard (aka "right") stabilizer part test fitted to the installed tail spar, to which I tried Ron40's suggestion of adding a strip along the top. This was more for a 'test' than any real need.

With the stab in place there was a problem - the alignment profile on the vertical tail is in the wrong position, as visible in the second image. If the tail is mounted as marked, the 'rudder' would not be able to deflect. At a minimum, the elevator hinge line should be in-line with the rudder hinge line (per third image, showing stab shifted forward.)

Just to note, I didn't much care for the amount of 'cut edge' showing on the trailing edges of these surfaces, so I tried a different technique on the port stabilizer.

(To be con't.)

[rbeach84]

I'll use the port stab to illustrate how I put together these parts. The first image shows the part as cut from the sheet. I then flipped the part and used an emery fingernail sanding "stick" to thin ("chamfer") the mating edges of the part. My idea is that this leaves less thickness to show the white of the paper stock, plus the trailing edges will look "sharper".

Then I flipped it back over and used the burnishing tool (smaller end) to create a shallow 'groove' along the control surface hinge line. I did this on the elevator side of the line, hence the position of the straight-edge, to simulate the fitment of the elevator. I tried to keep it to the right of the line - slightly noticeable in the third image. Then back over again, where the burnished line is visible on the reverse. I then used a larger radiused 'tool' (actually a 'putty applicator', similar to a common clay sculpting tool) to burnish an opposing curvature, not on top of the original, but to the left of it (as oriented in the last image.) The goal was to approximate an airfoil profile in the elevator.

(To be con't.)