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Curtiss Mohawk In RAF service

Started by Carl Smoot · 190 ≡ · ↻ 5 hours ago

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Carl Smoot said 1 week, 3 days ago:

The fragility of the detail on this motor is requiring me to glue each piece and letting it set for awhile before doing the next. The wires on the left will need to be trimmed to length and then glued to the cylinders before I can stick the opposite side wires on. This is partly because these the wires are held in place by CA glue and hope! 🙂
Spiros Pendedekas said 1 week, 3 days ago:

Superb! Absolutely superb job, my friend @clipper!
John vd Biggelaar said 1 week, 3 days ago:

This is really impressive, Carl @clipper
dale travis said 1 week, 3 days ago:

@clipper There is another option, and a good one if you can find it, the Medallion Models Hawk 75 kit. These kits are from the early 90's and are very accurate as the maker used the Paul Matt drawings as a reference. Very sharp work on this build!
1 attached image. Click to enlarge.
Carl Smoot said 1 week, 3 days ago:
Thanks Spiros (@fiveten), John (@johnb), and Dale (@dtravis)!

Dale, I have not heard of this kit before, and in 1/48 scale. Interesting. This is my second Cyclone powered Hawk build and if I had known about the Medallion kit when I did the first one, I might have been able to go a different route than I took.

That first build was the Hobbycraft Hawk 75 fixed gear kit done in Thai markings. The cowling on the HC kit is completely wrong, so I modified a Monogram B-17 engine and cowl and made changes to the kit to marry them together. It was a fun project at the time but I think the cowling was still a bit large.
1. The Hobbycraft kit I converted in 2019 using a modified B-17 cowling and engine
1. The Hobbycraft kit after finishing. One of my earliest efforts since returning back to modeling so the weathering is a bit rough.
Carl Smoot said 1 week, 2 days ago:

The engine is mostly done and installed. I want to do a oil wash and some highlights, but I can begin working on the next phase, which is installing the cowling. I started to assemble the cowling which is made from six pieces, but realized that I couldn't get the engine inside of it and quickly pull part of it apart before I couldn't. Dumb mistake on my part and it comes from getting in a hurry. Fortunately , no serious damage to the cowling.

However, when I started trying to test fit the cowling, I found that it won't fit over the engine without some internal grinding first. No problem. I can do that , then paint the inside before installing.

As for the engine, the spark plug wires worked out pretty good while positioning them. Only one broke loose from the harness and had to be reinstalled. And for the most part, the paint on the lead wire did not chip. I used some stretched tubing to place over the wire and glued to the ignition harness to make it look a bit more like the real thing. I was going to do that at the spark plug end, but it was just too small for me to do properly.

This kit engine really is very nice and the end result rivals anything I have seen in aftermarket except for the latest 3D printed marvels (that cost more than the model did). ClearProp is to be commended for delivering a very nice model. I will say however, that from an engineering perspective, there could be some improvements in the positive locations of parts. Also, the wiring harness does not have enough points for all the cylinders. I ended up adding to wires into the top of the front casing for the top cylinder. And the exhausts on the back are only enough for 8 cylinder instead of the nine on the motor. I am not sure why this is this way, but from a practical standpoint, you won't see these anyway, so it is a moot point.
Spiros Pendedekas said 1 week, 2 days ago:

Excellent job on the engine and really great that you managed to solve the cowling issues, my friend @clipper!
John vd Biggelaar said 1 week, 1 day ago:

A fine looking engine, Carl @clipper
Carl Smoot said 1 week, 1 day ago:

Thanks Spiros (@fiveten) and John (@johnb). Unfortunately, the cowling does not fit over the engine very well and I am having to sand down quite a bit of the inside of the cowling as well as a small part of the rocker arm covers on the engine. Nothing that will be noticed when finished, but I can't tell you how many times I've dropped that round cowling trying to hold onto it while I worked on thinning the inside surfaces!
Carl Smoot said 6 days, 13 hours ago:
After removing quite a bit of material from the interior of the cowling and a bit off of each rocker arm cover, I got the cowling pieces to fit. There will be a bit of seam work required at the top center and possible the cowling ring. The later may just be an optical illusion from the paint over spray, however. I also got a bit carried away on material removal and had to repair the trailing edge in one area of the cowling.
1. Repaired trailing edge
1. You can see how much material had to be removed
1. Cowling now fits fairly well. Need to do a bit of seam work here.
When the last piece of the lower cowl is added, most of the detail on the motor will be hidden, so I wanted to add this last picture which shows how tightly cowled the motor is.
1. A shame that all the nice detail on the sides and back will be hidden once this last piece of the cowling is added
Clear Prop makes a nicely detailed radial. All I added (besides paint) were the spark plug wires and a data plate on the lower center object between the cylinders. You can see just how much length Curtiss went to get the radial engine cowled with minimal surface area. It's no wonder this aircraft was able to do well against more modern aircraft.
1. This is all that will be visible of the motor. Clear prop makes a nicely detail radial for this kit.
John vd Biggelaar said 6 days, 13 hours ago:

Very nice progress, Carl @clipper
The cowling fits nicely this way, indeed a pity that most of it will be covered but the front view of the engine is still amazing.
Spiros Pendedekas said 6 days, 7 hours ago:

Excellent progress and great looks, my friend @clipper!
Carl Smoot said 5 days, 3 hours ago:
Thanks John (@johnb), and Spiros (@fiveten).

The seam work is mostly done now. Just a small amount to do on the horizontal stabilizers.

I started thinking about the fragmentation bombs that will be hung under the wings. These are 20 pound anti personnel bombs and are not very big in real life. IN 48th scale, they are only 1/2" (approximately 13mm) in length, so quite small. I've looked around for these in aftermarket and have not had any luck finding them, so I have resigned myself to making them.
1. These will be approximately 1/2" long (13mm) on the model. I will cast and assemble the basic tear drop shape and then use brass tubing for the tail fins and styrene rod for the forward section.
Unfortunately, I need 8 or 10 (can't remember which at the moment). I originally though about casting them in silicone, but they are so small that it would be a waste of silicone to make the mold and I would have to cast a single bomb each time. Too slow.

So putting on my thinking cap, I thought about casting them in halves (lengthwise) by pressing the master into thermoplastic or maybe clay. I could press the master in 10 times and cast the halves. Then cast another 10 halves and then I would just have to glue them together and clean up the seams. Still a bit tedious, but would go much quicker. And to speed up the process, I can use UV cure resin rather than casting resin. I can add a bit of acrylic paint to the resin to make the parts more visible.

That does present a bit of a problem in that the halves will need to be exactly 1/2 of the bomb longitudinally and have flat bonding surfaces. Using a syringe, I can precisely place low viscosity UV resin (which I have) in the molds. But I will need the molds to be the correct depth as well. So I am going to rig up a length of something (probably plastic bar) and attach the master to it hanging off the side, lengthwise. I'll place the mold material inside Lego bricks so I have a consistent height to rest the bar on when I press it down. This way, each pressing should be the same depth.

As added insurance, and assuming that I am still going to need to sand the bonding surface flat, I have laid out a half template of the shape of the bomb which I will cut out of styrene on my vinyl cutter (or maybe make it from a piece of soda can). I will use this half template to make sure the halves are all consistent in thickness.
1. This is the basic bomb shape I will cast. Then add the details after assembling the body.
I realize this may sound a bit confusing at the moment, but as I start the process, I will post pictures.
Spiros Pendedekas said 4 days, 22 hours ago:

Sounds very exciting, my friend @clipper! Looking forward to see it materialize!
John vd Biggelaar said 4 days, 20 hours ago:

Another challenge you are starting with, Carl @clipper
Definitely looking forward to it. Have you thought about 3D printing them?

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Curtiss Mohawk In RAF service