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Good day to all;

It's been a while since I have been on the boards.

I would like to fabricate the following engine derrick/crane

b17-004-1.jpg

A-20Amechanics.jpg

If I remember correctly, there might be a drawing of it's details in one of the Squadron-Signal books. Would anyone have further information?

Thanks in advance!

-Al

Edited by Blackcollar
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G'Day Blackcollar. Why don't you just scratch-build one from the photos? It looks like a locally-produced item (vs issued equipment required to change an engine). You need an outer A-frame and an elongate diamond-shaped inner frame. Note the widest point of the diamond-frame - it does NOT look like a hinge. From the photos, the length of each frame is at least about 24-25' long (= @ 4 x man-lenghts). Remember - it MUST be tall enough to hold the engine up the the face of the engine nacelle. From the photos, the feet of the A-frame are at least 4' wide (experiment when you scratch-build) to accommodate an engine and a man on either side. There are 3 x HD wheels. The pulley - un-powered, it is operated by pulling on a long loop of chain - is about 125% of the diameter of a human head. There is a link from the bottom tips of the A-frame to the bottom tip of the diamond. You can see it in the Boston photo (steel wire rope or steel rod?). IF the widest point of the diamond WAS a hinge, the whole thing can be collapsed for easier relocation, but won't collapse whilst holding-up an engine ND, the crane could be made taller, if required. If SWR, could it be shortened to make the crane taller? I'd build it with 2-scale" thick rod/pipe (compare it to thickness of the engine mechanic's arm).

(edit - there is a cable(?) link from the tip near the pulley, back to the back tip of the A-frame (see Fortress photo), down to the bottom tip of the diamond (see truck in Boston photo).)

FWIW, on the diamond frame, I would have expected a 3rd length over the top, which would be connected to both sides of the diamond, with a zig-zag of bars/rods. Such a frame (= a Warren truss) is pretty strong.

It is a pretty-simple scratch-build. So, take a deep breath, and have a go. I (and I'm sure that there are other modellers here) reckon that you CAN do it. Good luck with your attempt, and have fun. George, out................

Edited by The Loggie
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