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Jan 31, 2019, 12:40 PM
low tech high tech
vtdiy's Avatar
Thread OP
Printed out plans on legal size paper. Uhhhh they're awfully light....maybe I should have used a heavier line weight, you think? I don't usually build from plans, unless they're somebody else's. Let's see what I did here...... need glasses for this.

Okay, I cut out the patterns roughly and oversized, because I'm going to glue them down onto to some cardboard. Then I'll cut them out to the actual lines. Very few pieces to cut out:
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Jan 31, 2019, 01:23 PM
low tech high tech
vtdiy's Avatar
Thread OP
I sprayed the backs of the patterns with 3M stickum stuff outside on the porch (man it's cold!) brought it in quickly and turned the pieces over onto a piece of cardboard poster board (sometimes called Bristol board). But you can also use cereal box cardboard, or anything similar. Poster board is nice because it's big and easy to fit everything on. Anyway, stuck it all down and smoothed it out. Then I cut everything out to the (faint) lines.

And here are my patterns:
Jan 31, 2019, 01:52 PM
low tech high tech
vtdiy's Avatar
Thread OP
So, a few big decisions to make..... re. construction:

Fuselage -- either solid 2" thick block and hollowed, or 1-1/2" thick with two 1/4" cheek pieces (monoblock style cut-outs). I'm for sure doing foam here, not balsa.

I have 1-1/2" and 1/4" foam so monoblock is what I'll use, because it's simpler and cleaner to do a hollow interior.

And the other question(s):

Foil? Man I really want to do an undercambered plate, because I know it will work, and it will make a nice slow flyer for my small field.

But the original was flat plate, and I really want to see how that might work out. The simplest and original wing build method for this plane. So I'm going to resist the UC bias on my part, and just do this as an experiment as a flat plate.

I expect it will want more speed to stay up, and may need some elevator to keep the plane flying if I stick with the original incidences. But who really knows -- that's why we try things before pronouncing judgment. I can always change things after if they don't work well for my purposes.

Okay, if flat plate, do I go with balsa, as I earlier suggested, or foam?

Well I just checked my balsa stock and I have no 3/16". I have a sheet of medium weight 4" x 36" that a mouse chewed all around the edges, and I have another hard pristine sheet that feels like it's made of oak. I weighed it and the wings would weigh an ounce and a half, just in (oak quality) wood alone. By contrast, Dollartree foam with the paper on would weigh a little over an ounce, and stripped of paper, would weigh 2/3 ounce.

I also have some blue fanfold left and peeled, it would weigh about the same as peeled DT foam. It's a little stiffer than DT foam, which is helpful.

I like a painted model, and I want to keep this one light, so I think I'll do it peeled fanfold. There may be enough stiffness for these 11" wing panels, especially with the bipe's wing struts, without any additional reinforcement.

Okay, so that's the (present) plan....
Jan 31, 2019, 02:12 PM
Ken's CAD Models
dz1sfb's Avatar
How about a fold over fuselage on the line between the cockpit and vertical stabilizer and that will form the taper of the fuse, with a few formers to finish the shape and a flat sheet to close the bottom. DT foam with the paper removed is very shape friendly and light.

Remember that these models were originally control line models, that flew, but not too good. There small wing area, relatively heavy weight, and low power, were all factors that could be somewhat overcome by being attached to strings. Now you're going to RC and foam is a good choice that will greatly improve the wing loading. However, I would think that some form of airfoil will greatly benefit the model over a flat plate wing. I remember my 27" Foamy Rascal that was built to the original Rascal size. It had a slight undercamber and weighed in at 3oz. Power was an E-Flite Park 180 with a 2s 250mAh battery and 5g servos. As light as it was, it easily penetrated the wind, and would still fly slow.

I'd go with a light undercamber so it does not have to fly too fast to stay in the air and not have to fly with a nose high attitude in slow flight.

Ken
Last edited by dz1sfb; Jan 31, 2019 at 02:25 PM.
Jan 31, 2019, 02:39 PM
Ken's CAD Models
dz1sfb's Avatar
Remember also that these designs required very little roll and yaw stability.

Ken
Jan 31, 2019, 03:15 PM
flyin' fool
goldguy's Avatar
Scientific they were not by todays standards. I'm going with a 'full house' TLAR in '*squint scale' when compared to the original.

* Stand back 20 feet and squint. If it looks right, then it is.
Last edited by goldguy; Jan 31, 2019 at 03:21 PM.
Jan 31, 2019, 03:26 PM
flyin' fool
goldguy's Avatar
Check out these simple Ebenezer models. Simple free flights that flew up a storm .

https://www.google.ca/search?q=ebene...w=1280&bih=866

Here's one RCd' .
Jan 31, 2019, 03:33 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Hmmm, slight undercamber with some half-ribs to keep shape. I like the idea of the rolled over foam at the top.

What about the Kestrel? Yours truly has too many builds in the works...
Jan 31, 2019, 03:37 PM
low tech high tech
vtdiy's Avatar
Thread OP
Thx DZ1, I've designed for a fold-over sheet fuse before -- see my UL "Unfinished Business" bipe thread for a big one. I'm purposely going with the log style carved fuse, and flat wing, just cause I want to try to mimic the original Scientific style of construction for fun.

If anybody else wants to build this or any other Scientific 1/2A C/L plane adaptation with any other type of construction, have at it! Please post here, I'd love to see them!

Back to building......

I cut out the flat pieces using the patterns as guides:
Jan 31, 2019, 04:11 PM
low tech high tech
vtdiy's Avatar
Thread OP
Marked the fuselage and cowl out on a builder's scrap of 1-1/2" thick insulation:
Jan 31, 2019, 04:16 PM
low tech high tech
vtdiy's Avatar
Thread OP
I then cut both parts out with my trusty hacksaw blade, and sanded them to the lines.

With patterns at hand, it took 7 minutes to mark and cut these out. I have a total of less than an hour on this build so far, including making the patterns.
Jan 31, 2019, 05:06 PM
Rough Landing
rainyday101's Avatar
Quote:
Originally Posted by goldguy
Check out these simple Ebenezer models. Simple free flights that flew up a storm .

https://www.google.ca/search?q=ebene...w=1280&bih=866

Here's one RCd' .
Sold as a kit for RC at Retro Rc:
http://retrorc.us.com/katana-3-2-2-1-1-1-1-1-1.aspx
Jan 31, 2019, 05:59 PM
low tech high tech
vtdiy's Avatar
Thread OP
I made a second cardboard pattern of the plan view of the fuselage from the first. The reason was, I had to deduct 1/4" from each side to accommodate the two fanfold cheek pieces.

This was easily done by first tracing around the original pattern onto cardboard, and then marking a few points in 1/4" from the edges. Then lining up the first pattern with the dots and tracing the new lines.

The second pattern was cut out, and lines for the top and bottom of the foam blank marked out. I also drew lines connecting the upper and lower lines along the rudderpost.
Jan 31, 2019, 06:04 PM
low tech high tech
vtdiy's Avatar
Thread OP
I then scored along all of the lines about a half hacksaw blade depth into the foam. This provides guides, kind of like a miter box's slots for sawing all the way through.
Jan 31, 2019, 06:12 PM
low tech high tech
vtdiy's Avatar
Thread OP
Next step in cutting the foam fuselage is to saw in about an inch at a time, alternating around all of the cut lines, including the rudderpost set.

By alternately cutting from all directions you increase your effective "guide" depth, and you halve any possible error which might have shown itself if you tried to cut all the way through in one go.


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