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G'day Guys,

I'm thinking of making a UCAV as my first scratchbuilding project. I've chosen this subject as UCAVs obviously don't have cockpits, generally use off the shelf undercarriage, and are generally fairly small. I'm thinking of building a notional UCAV instead of an actual one, though the finished project would be similar to the X-47.

x47-3[1].jpg

However, I'm unsure as to how to go about building a symmetrical, curved fuselage/body.

Any ideas? Does anyone know how to create accurate cross sections?

Cheers,

John

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John, are you familiar with "plank on frame" as in model shipbuilding?

If you get accurate cross-section templates....cut them out from Evergreen strips, then place them on a "spine" at the appropriate distances, you can fill the gaps with epoxy putty, sand/carve to shape and even possibly make a mold of it for resin later (so others can have a kit, too :cheers:

I used this method to fashion a scratchbuilt nose for a 1/32 T-38 and there was an article in an oollllllllld FSM by a fellow who did an X-29 that way in 1/48th (no kits or even a suitable base for a kit) He found the F-5 woudn't work at all....even thought there was some resemblance....but the X-29 was totally different even in the fuselage, so he attacked it with ribs made of styrene, epoxy putty and styrene wings.

HTH

air

Or carve one out of wood and use that as a mold master.

For symmetry, you only need one set of templates, left or right, and then flip them over for the other side.

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G'day Airbusteacher,

Thanks for the quick reply! :cheers:

I have considered that approach, but unfortunately I don't have access to plans with cross sections, as the UCAV would be based on speculative drawings.

Unless someone knows how I could design my own cross sections? I know I'm asking a lot...

Hmmm.... I may have to experiment!

Cheers,

John

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John....

Ok.....

Draw the sucker in plan view. That is, from the top. Do this on Graph paper.

Transpose the drawing to cross section by making sure the length of each section is the same. IN other words, you have to imagine in your mind what it would look like in cross section.

You would take the plan view....carry a line over to the right (or left) and you already know the one dimension. Then, workign within the confines of the known dimension, you draw the unknown one.

I could give you a fer instance if I can find any of my tech drawings...but I think they're all in storage.

Or, buy yourself a copy of the computer program X-Plane and make one that actually "flies" in the computer. A great program if ever there was one. :cheers:

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John:

If your looking to do the X-47 in 1/72 scale then just go out and buy the Unicraft Kit. I built one last year and other than the normal resin issues it went together well. Unicraft has a bunch of UAV's and UCAV's. I have the X-45 complete, Goblahawk about 90% done and plan to start the DarkStar shortly.

Mark

PS: http://www.unicraftmodels.com

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G'day Mark,

I've seen the Unicraft models, and will buy one in the future. Do you have any pics of your build online? I wouldn't mind seeing it.

However, the UCAV I'm thinking of scratchbuilding is vaguely LIKE the X-47. I just used the pic by way of example.

Cheers,

John

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G'day Airbusteacher,

I think I've come up with a way of producing a symmetrical airframe. As I'll be building a notional UCAV (and not an actual one), I've got a bit of leeway i.e. I will determine the final shape of the airframe.

Step 1: Cut the planform of the UCAV out of styrene sheet.

Step 2: Cut out the side profile of the UCAV, and then cut it laterally into two pieces (representing the profile of the fuselage above and below the wing). Glue these along the UCAV's centreline, above and below the wing.

Step 3: Add roughly shaped bulkheads at regular intervals on one side only, above and below the wing. These will be glued on with superglue.

Step 4: Using progressively finer grits of sandpaper and a sanding block, the bulkheads will be sanded to their final shape.

Step 5: Once the bulkheads have been sanded to the correct shape, they will be numbered sequentially. They will then be snapped off the airframe, and will be used as templates for the bulkheads on the other side of the aircraft.

Step 6: All bulkheads (on both sides of the airframe) will be glued back onto the aircraft sequentially with superglue.

Step 7: The gaps between the bulkheads will then be filled with two part epoxy putty, and the airframe overall will be sanded to its final shape.

What do you think?

Cheers,

John

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Hi John

Sounds like you have a technique now, but just thought I would refer you to Jerome's work, posted on this site recently.

His site, which contains detailed pictures of his scratchbuilding is at

http://jerome.olympe.ch/

I asked him once how he carved the basic shape of the airframe and this was his reponse:

now, for carving, you need to make a template (cross section) (and actually two templates, one at each end).

The one one the pic is paper -- just to show, i can't find the original ones, they were made of fiberglass plate. Drill little holes to pin the template on the foam and draw some kind of ticks for synchronization with your buddy giving a hand at the other end. Of course, you need the same numbering at the other side.

[PIC]

then take your custom-made hot wire saw and gently run around the template (usually make one side, turn the block over and do the other side). Here you might recognize the X-15's cross section...

[PIC]

Hope that helps...

- jerome

You should search in 'In-progress Pics' for this post to see the pics he included in his reply.

Also, it is possible that this method only works for a shape which has a uniform cross-section from front to back, for at least a large part of the fuselage, but you may be able to modify the technique.

HTH

AndrewL

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Airbusteacher,

Cheers, mate, thanks for the tip! :thumbsup:

Andrew,

Thanks for the link to the site. I've had a look at Jerome's X-15, and I think the technique could be quite useful. ;)

By the way, I'm thinking of building the AVPRO designed Archangel UCAV (sorry, but the picture is very large!) :wave:

Cheers,

John

ucav-3-avpro-archangel_001.jpg

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