How's my math? And scratchbuilding a 1/350 helicopter?

Question

1. I have a 1/350 scale model USN Cruiser. I want to scratch build a 1/350 Piasecki HUP-2 helicopter, circa late 1950s, to sit on the back of the ship (I don't really want to scratch build it, but there is no 1/350 scale HUP-2 out there).The actual ship is 717' long. The ship model is just a hair over 24-1/2" long. At 1/350 scale, that's about right.The HUP-2 was 32' long, which works out to 1.097 inches, or 1-3/32" in 1/350 scale, correct?.If correct, we'll just round it off to 1-1/8"2. What would be a good medium to create this helicopter body? At this size, it would have to be something that would produce a smooth finish when filed to shape and sanded. I intend to use some PE scraps (sprues) for the rotor blades and some thin music wire for the wheel struts. All clear side windows will be painted black. I don't know what to use for the clear bubble on the front. Maybe some acrylic gel like Liquitex.I suppose I could get some generic 1/350 USN aircraft decals for it.Any suggestions?

frank · Accepted Answer

How about Plexiglass or Lexan or Acrylic? In that size, it shouldn't betoo hard to work with & then you could just polish out the clear bubble.

Kurt Laughlin · Answer

"willshak"  wroteA little longer than 1-3/32, but yes, your math is right.  Why use 1-1/8?The width was what, 8 feet or less?  I would laminate some 1/8 thick Evergreen sheet rectangles together, cut out the profile with saws and files, then sand/file the fuselage shape.  (This is what I did to make a 1/350 SS-1 HOLLAND VI submarine.)  You could cut a notch at the front and glue in a piece of acrylic and sand to shape for the cockpit.  You could probably get passable landing gear and rotors from other 1/350 helo kits and PE frets.KL

Greg · Answer

I second the acrylic suggestion.

I've whittle a lot of master parts out of acrylic and find it to be an excellent choice. It is very hard and therefore holds sharp edges and crisp detail much better than styrene. It polishes up crystal clear. It is manufactured in thickness from 1/16" to two inches or more.

It is a little more difficult to work. You need sharp tools. You can't carve it with a knife, but it saws, files and sands just fine. One oddity is that you can GRIND it very well. It's melting point is much higher than styrene and you can work it with power tools without fear. You can do the rough shaping quickly with a bench grinder, die grinder or even Dremmel. Use a coarse grind stone.

Conventional solvent based glues and putties do not work well. You are best to work carefully and avoid having to use putty. You can solvent weld it, but it requires really nasty stuff (MEK and EDC) so you are better of just using super glue (also an acrylic).

I do not recomment laminating styrene sheet to get the reguired thickness. It takes AGES for the solvent to work its way out of the plastic to the point that it will not leave a witness line on the exposed surface.

Greg Reynolds, IPMS

willshak · Answer

That sounds good, and I do have some 1/4" acrylic sheet laying around.

1/4" works out to 7.3 feet in 1/350 scale so it is more than thick enough. If it works out and looks good, I'll post some finished pics over in a.b.m.s. If it doesn't look good, I'll say I never made it. :-) Thanks..

willshak · Answer

Thanks. I've already considered Frank's acrylic suggestion. I have pieces of 1/4" acrylic sheet laying around, which is more than thick enough for the width of the helo, and all the mini tools necessary to do some sawing, grinding, and filing.

willshak · Answer

4/32" = 1/8". That will take care of the 'little longer'.

Frank's suggestion to use clear plastic sounds better, in that I can paint everything except the cockpit and side windows, which will allow a little light through the fuselage. I do have pieces of 1/4" clear acrylic sheet laying around which will be more than thick enough. I don't know the width of the helo, but it couldn't be more than 6 feet, and possibly only 5 feet wide, at least from what photos I have seen.

1/4" works out to 7.3 feet in 1/250 scale, so it is more than thick enough. I don't have any other 1/350 helos and wouldn't want to buy one just for the struts and wheels. I have enough PE sprues to make more than 6 blades. At this scale, how much detail can be shown anyway? The only problem I foresee is with my clumsy hands, and maybe decals. Thanks.

willshak · Answer

Typo: I meant 1/350 scale, not 1/250 as above.

Charles Metz · Answer

--snip--Your calculations are correct -- and 1-1/8" (1.125") should be close enough, since the discrepancy would correspond to an excess of only 9.8" in length on the real aircraft.   Charles Metz

How's my math? And scratchbuilding a 1/350 helicopter?

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