Scale UH-1H 450 Class Custom Build Project

[Highspeed1964]

I have been chronicling (in photos) a custom UH-1H "Huey" project I am building on my FB page for a couple of weeks, but wanted to post here for you all to enjoy as well. I will detail all the steps I have completed to date (separate post for each day showing the progress made that day) as well as future updates as I continue to progress through the build.

I will detail the good, the bad and the ugly as I want to share with you my triumphs and my mistakes so that hopefully someone following through this will be able to learn from all aspects of my build - positive and negative.

I have hit a major set-back and am taking this opportunity to take a breath and build this thread for now. It gives me a chance to step back, re-collect myself and get a fresh start on this project. I'll get to the cause of the set-back at the proper point in my posts, but I am starting at the beginning - one step at a time.

First, the goals of the project:

1. Build an accurate, realistic 1/18 scale frame from balsa wood using actual maintenance manuals downloaded from the public domain. Included in these documents are drawings showing proper placement and measurements of the airframe components in both plan view and side elevation as well as a 3-dimentional perspective view.

2. Once the airframe is complete, I will put the "skin" on it, most likely a monokote covering painted, sanded and finished to a high level of detail.

3. This will then be used as the "plug" to create a fiberglass mold from which I will cast a fiberglass shell. This will include re-enforcements in key areas to provide support, structural integrity and mount points for the internal mechanics and electronics to create a flyable RC model.

4. The finished product is to have all facets of a realistic model including an open cabin, fully modeled cockpit, a custom machined rotor head and rotor system that will function just like the real aircraft, servo controlled sliding cargo doors and an articulated horizontal stabilizer synchronized to the fore/aft movements of the cyclic controls just to name the most notable features I anticipate incorporating into the finished model.

5. A hinged/removable cockpit to provide access to the battery and other potential components anticipated to be located under the floorboards for concealment purposes.

6. A longitudinally mounted electric motor to emulate the power/drive system as closely as possible.

Two additional considerations I might do would be:

1. Lock down the stabilizer bar and run a FBL (flybarless) system.

2. Try to replicate the tail rotor system as closely as possible within the limits of the scale I am building this model.

My intent (along with my flying style) is to keep it a scale flyer so I am not concerned with keeping the weight up close to the rotor system as one would for a 3D bird.

In addition to the hinged/removable cockpit, I want to make the tail boom removable much like the full scale helicopter I am replicating. I also want to make the main mechanical assembly removable for maintenance purposes but solid enough that it holds up to the rigors of flight.

I do not anticipate this to be a quick project, especially as my skills in this area are quite limited at this point. I have built exactly one balsa framed aircraft and that was from a kit. And it was a static display model at that. This build is much more complex and each part is being designed from scratch using the aforementioned documents and any pictures I can find on the internet along the way.

This project is likely to take months if not longer. Hopefully those of you who will be following this thread will not get bored and lose interest along the way.

I thank you in advance for your interest in this project and may call upon you for your input when I come upon any stumbling blocks. (I think of them as opportunities for learning and skill enhancement.)

Stephen "Highspeed" Kruse

[Highspeed1964]

Note: The first few posts (Day 1 through Day 6) actually took about 2 weeks at a couple or so hours per evening. Due to my schedules and other interests, they were not consecutive days. But as I said in my opening post, I have already been blogging this on my FB page so I have just carried the pictures over to here and outlined the processes each day. The remainder will come as I progress.

The first step was to begin creating the templates for laying out the parts. I started with the tail boom thinking this would be the easiest component. I extracted the size of the bulkheads both vertically and horizontally down to the 1/18 scale I was shooting for and laid out the dimensions on paper to create the first template.



Then I rough-built the assembly using this template as a guide. I do mean "rough built" as it came out far less than what I had hoped for and I will have to go back and re-do it. Some parts were crooked, the stringers got broken along the process, etc.

Here is the top vew...



...and side view laid out against the template. For this side view, I also loosely placed in the main spar for the vertical stabilizer just to get a vision of what it might end up looking like.



Next I created the template for the passenger cabin roof frame and then placed the tail boom next to it to get a good reference for the size this thing will be. (That template was actually part of day two.)



Highspeed

[Highspeed1964]

This is the template I made on day two for laying out the frame of the roof of the passenger cabin section. Again, the measurements were extracted from the drawings I had available to me and converted to 1/18 scale.



Then I started the actual build by placing the four main beams and the front bulkhead cross member.



Next I added in more of the cross member components.



I will be doing the same for the cabin floor/aircraft hull but enough for tonight. Don't want to rush things and as you see, there's not much shape to it yet. I sill have some runners and ribs to add in before sanding to the final shape.

Highspeed

[Highspeed1964]

A new day and another component framed out. This is the cabin floor/aircraft hull that will be the main part of the helicopter. Of course, the first step is to lay out the template.



Next is the main beams and major cross members.



Then the addition of the frame components that define the fuel cell pockets. And again, the ribs and runners that define the shape will be added in and sanded at a later stage.



Here I've laid the two sections side by side for comparison. The cabin floor is a lot thicker than the roof section, but that is true to form on the original, too.



Highspeed

[Highspeed1964]

Now that I have the floor and roof sections initially framed, I wanted to see what the thing would look like as an assembly. So I measured and cut some temporary vertical pieces and tacked them in place.

This is just different views of that test fitting. It seems this main body is going to be quite huge (those are 8 1/2 x 11 sheets of paper I used for the background) in comparison to our everyday 3D flyers. Still, It is going to be approximately 28" tip of the nose to the tip of the vertical stabilizer.









Highspeed

[Highspeed1964]

I have finished the framing of the roof and floor sections. Now it's really starting to take shape! I know, it's not much work for today but did I say... "I'll be taking it slow and working just a little bit at a time"?

The roof. Yes, it's up-side down.



The floor all framed out and ready to sand to shape.



Again, both laid out side-by-side.



Highspeed

[islrcr1]

Subscribed! Love that heli, and looking forward to seeing your build.

[Highspeed1964]

Well, now it is really starting to look like something. I have sanded the hull frames to shape, tapering the lines and rounding out the corners for a smooth contour before I assemble them together with bulkhead uprights for final shape. The sanding is rather rigorous on the components (I had to stop and re-glue some components a couple of times or so during this process) so I didn't want to risk breaking too much by sanding after assembling the two sections on their upright bulkhead members.

I placed the components with the shaped sides up and in all four orientations.

Fore looking aft.



Port looking starboard.



Aft looking forward.



And starboard looking towards port side.



Again, not a whole lot of progress but it did take some time to get it looking right on this step.

Highspeed

[Highspeed1964]

Well I had posted the pics of the progress for this day in another thread and HF wouldn't let me upload them again here. So I've had to link to the other thread for those images instead.

But it's really exciting to see this cabin taking shape now! Looks like I was able to imbed them with a different tool on this message post. It just means there are no thumbnails here. Just the full-size images within the post itself. Enjoy.









Highspeed

P.S. That's it for tonight. Next I will post the current phase I have just completed... including the set-back I spoke of. I just want you to be able to take in what I have accomplished so far before I go in to that.

[Highspeed1964]

Originally Posted by islrcr1

Subscribed! Love that heli, and looking forward to seeing your build.

Awesome! Thanks for your quick response. I'm sure you'll like what you see as I go along. But be prepared, my next post tomorrow isn't going to be all glitz and glamour. As I said, I'm posting it all: the good, the bad and the ugly.

I'm sure I'll need support along the way so hope you do hang in there with me.

Highspeed

[islrcr1]

I will be there all the way..... you are just across the pond from Vancouver Island, been to your town many times. I am not too familiar with the building process you are using but will help as much as possible.

[Highspeed1964]

Originally Posted by islrcr1

I will be there all the way..... you are just across the pond from Vancouver Island, been to your town many times. I am not too familiar with the building process you are using but will help as much as possible.

Yep, not far at all. We'll have to get together for a flying day or something sometime.

Well, I have a couple more posts to put up here. I forgot one set last night and then there will be the dreaded "set-back" set after that.

Keep in touch,

Highspeed

[islrcr1]

Looking forward to it....

[Highspeed1964]

Well guys, I was wrong! I forgot one more set of pics. Last night when I was making all my "daily" posts there was one more set I should have included. This is not the "set-back" set I referenced in a couple of my posts in this thread.

So day 7 involved framing out the Main Mast "box". This is the section that extends into the passenger cabin from the rear wall to accommodate the main mast and transmission gear-box. The main mast is located here (obviously) for center of gravity reasons.

The whole heli should balance around the point when fully built, including engine, electronics, avionics, fuel, etc. In fact the fuel cells are located where they are for just this reason. And it works out well since there is minimal shift in CoG as fuel is burned off. Unfortunately, it does put it right underneath the door gunner station!

Anyway, I had a hard time seeing much detail for this in the drawings I had available in the maintenance manual, so I scoured the internet in search of any reference pics or other drawings I could find that would give me a better look at that area. Northwest Helicopters, Inc. to the rescue.

This company specializes in refurbishing UH-1H helicopters and putting them into service for anywhere from Sheriff's offices to firefighting operations to larger groups. And they have some good pics on their Facebook website (look them up, there's a lot of good stuff there) and found exactly what I needed to complete this step. This one in particular:



So from that, I built this portion:



Here's the one showing the detail taken from the picture shown above from Northwest Helicopters, Inc.



And one more view from the cabin side.



Enjoy,

Highspeed

[Highspeed1964]

So after building the Main Mast box, I got to looking at finishing the ribs between the forward two bulkheads. The angles just seemed a bit tricky and I was not feeling as fresh (somewhat tired) so it really wasn't coming together in my head and I figured I'd just move on to something a little less complicated.

So I moved on to the next section - the engine and hydraulics bay section just aft of the passenger cabin. It's the tapered section leading back to the tail boom and terminates at the mounting bulkhead designed just for that purpose; mounting the boom.

I started building the lower frame which I would then attach to the (nearly) finished cabin that you've seen above. Well I built the rough frame as I have done with the cabin floor and roof sections previously. I went to attach it since the bulk of the framework for this section extends from cabin section as well as the lower frame I just built.

Here's where things got pretty frustrating. After attaching the new frame section, I discovered that the curves of the cabin section didn't look right. In fact, the more I observed, the worse it looked. In the pictures you can see how those curves actually intersect the new section in such a way that it would chop it off about a third of the way back.

Here's the pictures:

At first glance it really doesn't look bad. In fact, it's pretty exciting to see the shape starting to extend out.



However, closer inspection shows how the shaping I had done on the hull was too aggressively curved and would never be able to match up with the new section. The extended curve would end up just about the location of the first lateral spar on the new section when it should smoothly transition all the way back to the boom mount bulkhead at the aft section of the main body.



Also, looking down from the top, you can see the side curves are too aggressive (albeit not as much as the lower hull) as well. Those spars are cut to the proper length but the curves of the sides show that they would need to be a good bit shorter for the proper transition from the existing curves.



Bear in mind, this new section hasn't even been completed out to the full length. The main beams angle upward at this point to meet at the bottom of the aft bulkhead. And the more I thought about it, the more I realized there is no way I could add material in here to re-define the curves and make it work.

So basically, I'm back to square one on this build. Man! I was bummed! Disappointment really hit hard. A lot of work and time down the drain.



It's great that the Good Lord gave us resiliency in our brains. We are overcomers!

Yes, I have to start over again. But there were little things along the way that I would have loved to go back and do defferent or better. Little nagging things that most would even notice without some scrutiny. But to the builder... they really add up.

I also thought along the way that maybe I should have built this with the main beams build as a single piece fore to aft. I had been so focused on sectionalizing this for the final build that I OVER-sectionalized it. Had I built it with the beams as a single piece I probably would not have run into this issue.

I also realized that some parts were just a little askew and the whole thing just didn't have that crisp feel to it that I wanted out of the frame. I'd like to go back and keep things a good bit straighter and tighter tolerances in general

Well, now I have the opportunity to go back and do it all over again - correctly and accurately! So I am retiring "Prototype 1" and moving forward with a new build.

I've already started the drawings for the new main beams. I'll get some pics of that in the next post along with pics of the new lower hull frame I will be building over the next day or two.

Of course, I'll also have to redo the roof section as well. In fact, the aggressiveness of the curves is what made the forward bulkhead ribs seem like such a challenge as well. So again, another opportunity to excel!

Keep your eyes here for... PROTOTYPE 2!!!

Highspeed

[fastone93]

Nice Job, now hurry up I want to see it finished

[Highspeed1964]

Hey guys!

Sorry, I've been away a few days and have not had a chance to do any more on this project yet. I've been helping some friends move and just getting a chance to update this post. I'll be getting back on this in a couple of days or so.

Of course, tomorrow is Super Bowl Sunday and my team is in it second year in a row! Go SeaHawks!!!

But keep an eye on this thread and I'll have an update in a couple days or so.

Thanks so much for the interest.

Highspeed

[Highspeed1964]

So not much to show yet, but I have been working out the new design. Spending a little time getting it right this time. "Measure Twice, Cut Once" is the motto here.

I have created the template for the main beams and modified it so that I will be able to fit the battery under the floor boards. The trick is making sure there's enough room for the battery to fit over the landing skid struts. Now that I have that worked out, I'll begin the build by cutting these main beams out and adding in the spars, ribs and runners. After that will be the rebuild of the roof and bulkhead uprights.

Pics will be forthcoming as I progress along the build.

As always, thanks for watching this build. Your interest is appreciated.

Highspeed

[Highspeed1964]

Back to the build now.

I have been mulling things over in my mind a lot the last few days. Thinking through more than just the frame build, I am working on the mechanical design of the finished heli. Nothing really on paper yet, but I have a good design in mind.

I'll be using a planetary gear system to keep the gearing more compact. I've also got a good handle on how I'll tie the main shaft to the tail drive torque tube. Remember, I'll be using a longitudinally mounted motor so there was quite some wrangling with directional changes in my original thoughts. Using the planetary gear design simplifies things quite considerably.

But back to the tasks at hand. I have drawn out the pattern for the two main floor beams. Instead of measuring from one frame member to the next, I laid everything out in reference to the zero points; Station 0, Waterline 0 and Butt line 0 (longitudinal centerline). This is the way everything is measured in the real world and it helps keep things more precise on the model, too.

So here's the design for the main beams I drew up:



You can see the vertical lines drawn on the pattern. The are the station lines measured from station 0 which is a point approximately 7 inches back from the nose. Less obvious are the waterline markings. The long horizontal line will be the floor of the main cabin and is at waterline 22. The pilot's seats sit at the front part of this floor and ahead of that is a lower floor section at WL 19 and this leads into the opening for the anti-torque pedals.

At the back of these beams the upturned section leads to the aft bulkhead of the body. This bulkhead is where the tail boom mounts in final assembly. I will be making the tail boom separate and removable in the final product, but the frame will have it more permanently fastened. The fiberglassing process will be done in sections from the final skinned frame.

After drawing this pattern, I cut it out and used it to cut out the balsa pieces from which I will build the whole main body.



One other point of note (and one of the things that took me so long to get to this point) is that I wanted to make sure the floor of the body will be deep enough to house the battery on the finished fiberglass model. You can see in the picture of the pattern that there are two lines for the lower curved portion of the beam (the part that will define the hull shape) - the inner line was the original dimension of the hull and the outside line is how much I've extended it to accommodate the battery thickness. In scale it would add about 5 - 6 inches of depth, but on the model it is less than 1/4 inch so I figured it would be an acceptable change to the accuracy of the framed model.

After cutting out these two pieces, I sandwiched them together and rough sanded them to an identical shape.

Not much else to show tonight, but I want to keep things up to date with any progress I do make. I don't want anyone thinking I've given up after my previous issues. I'm more dedicated than ever in seeing this project through. I really can't wait to have the finished fiberglass shell so I can start assembling the mechanical assemblies. I really can see it in my mind and should probably start putting some of it on paper so it doesn't get lost in my aging memory.

Next session, I hope to show the floor and engine section framed in with cross members, fuel cell pockets, and other main structures completed. The session after that will be the ribs and runners just as I did in the first prototype. The roof will be the next piece which will then be installed on the uprights of the bulkheads. Then I'll frame in the back section which will house the mechanical and most of the electrical components and then finish up with the front canopy over the cockpit area.

Keep tuned for more as I work through this second build with much more care and precision than the first build.

Highspeed

[Tustainm]

[emoji106]


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