As previously stated, the engines in the UH-1F were larger, and the transmission/shaft connections required Bell to rework the engine configuration. The result was ducting and baffling to bring air into the engine from fore and aft. Forward of the rear clam-shell engine cowling hinges, the external appearance of the engine compartment is much like any other UH-1B/C model. But aft of those hinges, the differences are obvious. Refer to the photos above. The engine exhaust is vented to the right side of the engine compartment, while the left side of the cowling is distinguished with a large egg-shaped screened intake area. These features are unique to the UH-1F among Hueys. Note the location of the cubby storage area on the starboard side of the boom (left of the airman's elbow).
Since no manufacturor makes a 1:48 UH-1F, nor are there any upgrade parts available for this variation, I was tasked with making my own. I had been interested in learning to make my own molds and casting for some time, so now seemed as good a time as any. I had purchased suitable materials, and began by making a mold of the original Revell UH-1C model. I used some of the Lego blocks left in my attic by my kids to make a walled-in reservoir and dam to contain the molding material. I taped the model halves together, used modeling clay to plug the inside area to prevent getting much of the molding material into it, and used modeling clay to creat a dam between the Lego blocks and the outside of the model's curved surfaces. Placing the model in the Lego reservoir, I was ready to pour.
The molding material is a two part silicon gel that is fluid for about 15 minutes before starting to cure. Following directions, the pour was completed and allowed to set.
Lessons learned: Silicon molding fluid is very viscous and if allowed, will find a way to leak through. The modeling clay was not totally effective in preventing the material to leak into the model, and potentially more serios, through the Lego reservoir. Fortunately, I had placed the entire operation into a disposable baking pan, so nothing went farther than that. The leakage into the model was easy to remove making clean-up a non-event. In the future, I used clear food wrap (Saran) to line the reservoir and contained the leaks.
Next, I used a two-part urethane casting material to make a mold of the original UH-1C enging section.
I forgot to add that prior to molding the UH-1C model I had place some modeling clay around that aft portion on the engine to allow material for carving the new engine shapes. Above is the later smaller casting that emerged. After filing and contouring and comparing the new shape (did I mention repeatedly?) a recognizable contour began to take shape, and I drilled a hole where the exhaust would emerge, and added a blob of clay where the egg-shaped air intake would be.
At this point I was ready to make another mold and casting...
Here is the result of the second casting fitted onto the UH-1C model after some amputation.
Now the process of putty, filler, sanding, contouring, glueing....repeat. Athough there are warts and freckles and scars, I am pleased with the result.
I used Archer grid surface detail decals to bring out the screened effect of the air intake. The exhaust pipe is a contoured soda straw, trimmed and inserted into the hole, glued, and painted.
This is very much still a work-in-progress, so the roof, nose, skids, FFR pods, rotor head and rotors are not glued on, but mocked-up for the photo. I am presently building a pair of M134 miniguns to be mounted on either side of the cabin. Sadly, I purchased miniguns that did not have any sort of gun mount, so I am in the process of scratch building those tiny, teeny, did I say very small parts. Wish me luck and I may actually finish this build.