KITPLANES Magazine, May 1997
Building a RotorWay 162F
Part 3 of 8: Preparing the helicopter’s body.
by Jeff Dunham
Before we get to more building, I want to say thanks to all who have responded to this series so far. It’s a great inspiration in the building process as well as when banging on these computer keys! So thanks for the letters and e-mail and phone calls. Even my wife bought three copies of the March KITPLANES right off the stand!
As I mentioned last time, we’re deviating slightly from RotorWay’s building manuals in the order of construction simply because of my lack of building square footage in the garage. As you read in last issue, since the 162F kit goes together in stages, you can jump around to different areas of construction without affecting the outcome drastically. In my particular case, since garage space is limited, the 12-foot-long tailboom would just get in the way and get banged up.
If we had followed the plans exactly, the boom should have been mounted right after we painted the frame, but we’ll leave it in the crate for now. I’ll mount it after I haul everything to the hangar. According to Tom Smith at RW, tailboomless is how they build ships at the factory, as well as when they do heavy maintenance.
This Month’s Schedule
Last time we built and painted the landing gear and main frame, and I had temporarily mounted the main shaft/elastomeric rotor hub. In this episode, we’re going to fit the fiberglass body shell to the frame while temporarily assembling some of the controls. Building and mounting the body and the controls actually go hand in hand and affect each other during installation and in placement. The plans call for mounting the body first. After a good amount of trial and error, however, I suggest constructing both the body and the controls somewhat simultaneously. Why? It’s because there are a couple of areas in the ship where space is limited, with the body possibly hindering control movement or contacting other components, which would of course have to be corrected by either adjusting the body or the controls before final installation.
If you have either the body or the controls already permanently placed and then you try to fit the other subsequently, there’s a good chance you’ll have to move something and thus rebuild, and that’s not fun.
Even though RW uses jigs when welding the 162F frames, keeping everything to within strict tolerances, where every helicopter differs is with the fiberglass body. There are 15 major panels that make up the 162F body, and all are laid up by hand in the good old fashioned squeegee method at the RotorWay factory.
This results in high-quality, light and thin but strong pieces of fiberglass. But putting together the body shell is about like three different kids putting together their own Mr. Potato Heads. Even though the parts are all the same and each kid is looking at the same picture on the box, with a slightly different twist of the nose or ears, the toy will be a little different each time it’s assembled!
It’s the same with the 162F body. All the parts are the same, but it’s not a strict “Tab A in Slot B” assembly. There are joggles to match up, and guide holes to give you a good start, but if the thickness of each piece is slightly different, for example, then the guide holes might not line up exactly. There are a few other variables as well, so every ship will be slightly different.
Not including the paint, I think this is the only part of the helicopter construction that you might consider artwork! You need a good eye to get everything straight. Keeping all this in mind, you can see that anything within the ship that comes close to the body and body pieces, or anything that mounts with or to the body must be considered and watched closely when assembling the fiberglass parts. Thus, control placement is critical when trying to achieve a good fit.because they mount right through the body pieces in a few places. Get it?
So again, my suggestion is that a builder piece together the body, making as few holes for Clecos as possible. He should try to use the handful of guide holes RotorWay has provided and then test fit each control assembly when appropriate.
Following the Book
The seat back, tub and floor pan are the most critical pieces relating to control placement, and we’ll discuss each of them. I’ll also tell you when to put in each control so as to make the best use of your time and help with efficient construction. “Body Details” is the most lengthy section of the RW construction manuals, mainly because of the many pictures needed for good explanation and understanding.
It begins with the builder being instructed to “Cut out areas scribed for holes in the tub.” These are four holes in the tub, made for the landing gear to fit through. This is one of those areas that begins as a good guess. You have scribed areas where holes are supposed to be, but cut small enough and be ready to enlarge and move them, because no matter what, the holes will have to be adjusted.
Back to the Mr. Potato Head analogy: Every body is slightly different! The easiest way to cut these oblong holes is to drill a group of 3/8-inch holes within the perimeter of the scribed lines and then punch out the leftover middle section. Finish the edges of the hole with a small drum sander bit on a Dremel tool or something similar.
Before cutting the holes, however, make sure you use the right tools for drilling! Have you ever tried to drill a 3/8-inch hole in thin fiberglass using a regular drill bit? It ain’t much fun! About the time it penetrates the material, it grabs hold and tries to yank the drill motor out of your hand. Or, if you have a good grip, it’ll just tear the glass up in an ugly way.
Use a step drill or uni-bit, which has small increments of enlargement step by step and makes really nice clean holes in fiberglass. Some guys just drill the holes by running the motor backward using a standard drill bit, but to me that’s a big waste of time.
You have many 3/8-inch holes to drill for mounting Dzus fasteners, so be sure to take the time to find a uni-bit. I think Sears currently carries them.
After cutting the landing gear holes, you disassemble the front landing gear from the frame, pulling the gear in half, then reinstalling the halves through the front tub holes and putting the gear halves back together. Keep the tub in between the skids when installing the gear halves through it, so when ready, you simply raise the back part of the tub and push it back onto the rear landing gear, sliding the newly cut and open-end holes onto the rear gear.
Put a large cardboard box of the correct height under the tub to support it. It’s also not a bad idea to put duct tape around the inside of the holes in the tub to avoid scratching the paint on your landing gear with the fiberglass edges. It helps to have an extra set of hands during this process. The tub is mightily cumbersome.
Now bolt the front landing gear shoes back onto the skids. You don’t need to tighten any of these bolts to torque specs yet because this is one of those areas on the ship that will be assembled and disassembled a few times.
Next comes the mounting of the seatback. This is the most critical step in achieving a good body fit and should be done most carefully. The instructions call for taping scraps of excess interior liner material to the edges of the seatback before assembling the body. This is so that after assembling the body pieces, when you install the actual interior liner, existing hole alignment on the outer body pieces won’t be altered due to the liner’s thickness.
But I didn’t bother using the interior liner. This is just gray plastic stuff that is supposed to make the interior of the 162F’s cockpit look more like it’s factory built. In my opinion, it’s ugly, and a nice custom cloth interior would be much nicer. More important, the gray plastic adds considerable weight. Leave it out or regret it later.
The body of every RotorWay helicopter basically floats on the frame and makes very little contact with anything. The only part of the body attached to the frame is the seatback. It’s attached with two 1/4-inch and two 3/16-inch bolts. That’s it. So the reason it’s so critical to get this seatback in the right place is that every part of the body and its placement relates to where you mount the seatback. Gulp.
I guess now is an appropriate time to describe the magic of Clecos to the unfamiliar. You can see in a few of the pictures how they’re used and for what. Basically, a Cleco is to temporarily hold together whatever you’re working on before drilling the holes to rivet or bolt hole sizes. Cleco pliers are used to install the Clecos in these 1/8-inch holes.
RotorWay supplies the special pliers and a bag full of shiny new Clecos with every kit. Pretty cool. As the instructions say, you now bolt the seatback in with only two 1/8-inch holes and Clecos temporarily. When you get to the controls installation, if something needs to be adjusted, it will simply be a matter of adjusting the Cleco holes in the seatback, and then final drilling the two 1/4-inch and two 3/16-inch holes once everything fits.
Here’s where I’ll stick in one of those big hints to save you a lot of trouble: Once you get to the seatback installation and get it temporarily mounted, jump to the collective control construction and installation. Why? Because this is where a few guys run into trouble when trying to get everything to fit within a limited space in the helicopter. When designing the 162F, RotorWay squeezed as much cabin space out of the existing Exec 90 design as possible, effectively cutting down the fudge factor in the collective control mounting positioning.
It’s really a matter of fractions of inches here. You run into the possibility of the throttle assembly hitting the inside of the tub on the pilot’s side in certain positions. This happened to Mike Sherick on his ship, so his easy-fix was to cut a 3-inch round “inspection hole” in the left side of the tub. So instead of hitting the tub at 80% throttle and with a few degrees of collective input, now part of the linkage just barely pokes out of the hole allowing for full travel and extension of the controls. It’s actually kind of nice because he can look in and inspect stuff that would normally be hidden from view. He says even if the throttle didn’t hit, he might consider cutting the hole again anyway!
On my ship, there was no problem. Was I just lucky? Probably. I had positioned everything slightly differently and didn’t run into the problem.
The other area of the seatback placement that is critical in relation to the collective is how and where the collective stick comes through the seatback. As you can see in the picture, there’s a very small area in width for the collective stick.
As the seatback has to be placed in an almost exact location so that it sits comfortably on the frame, the only way you can adjust where the collective stick comes through the hole is how much you trim from each end of the collective tube, thus moving the assembly side to side. So put the seatback in what you think is the best position as called out in the instruction manuals, then take the collective weldment and temporarily position it to see how much of each end you’ll have to trim, and whether it will fit with the existing placement of the seatback.
(We’ll get to the actual controls construction and how they are mounted next month. Just as it is in the construction manuals, it makes more sense to separate the body installation and the control installation simply for clarity. I’ll do the same in these articles.)
Make sure that the Cleco holes you drill in the bottom of the seatback through the airframe are far enough from the edge of the seatback wall so that after drilled out to 1/4 inch, there’s enough room for the bolt’s head and a washer. On the other hand, you also need to make sure the hole is centered on the underlying pipe of the frame so the bolt can be mounted straight through. Take your time.
Next comes the floor pan. Before dropping it in, however, here’s another place for temporary control installation. Go ahead and cut the foot pedal tube to length and temporarily install it. You’ll also want to install the body support pads, which are rubber pads mounted on threaded rods that raise the floor pan up off the pedal cross tube.
You won’t find these pads in the instruction manuals, only in the blueprints. I guess they were added after the manuals were printed. No big deal. All you do is screw them in. These pads are an improvement from all earlier RW designs; in the old ships, the floor pan simply rested on the foot pedal tube, which was protected from chafing by rubber hose sections that were slid over the tube and between the pedals.
It worked fine as there was very little weight on the tube, and it resulted in very little friction during pedal and pedal tube movement. I guess somebody at RW figured it worked but still needed to be fixed.
After the initial positioning of the pedal tube and the floor pan, you can go back later during the actual control construction and final installation and mount the pedal castings. This involves cutting holes in the floor pan, but we’ll cover that next issue too.
Now install the floor pan. Trial and error will help you adjust it to a snug fit with the tub. As the instructions say, make sure you pull it as far forward as possible. Again: Don’t drill too many holes until you get the entire body mounted! Just because you get the tub, seatback and floor pan to fit doesn’t mean everything else will fit perfectly. The windscreen and doghouse can really throw you a couple of curves!
One more time: Mount every piece of the body with as few holes drilled as possible, then stand back and look at the ship from a few feet away, making sure it looks right! Also, the predrilled guide holes are not gospel. They are optional guides.
For example, on my ship, the two holes in the front of the floor pan didn’t line up with the two “matching” ones in the tub. They were off by about 1/4 inch each. Why? The tub thickness must have been slightly different from the norm. Again, no big deal, but I had to redrill to make it all fit happily.
Hold the floor pan in place onto the seatback using hand or small C clamps. This will let you avoid drilling unneeded holes. It’s a good idea to use rubber between the clamps and the glossy fiberglass finish too. The seatback and floor pan are already finished with handsome shiny black gel coat that’s tough to repair once drilled or scratched. Be careful!
Once the tub, seat back and floor pan are in place, finish the collective control installation, including connecting the collective rod that goes from the control weldment up to the elastomeric rotor hub. The reason for this is to make sure there’s clearance between this aluminum pipe/rod and the back of the seatback.
Now you begin to hang the other body pieces. These include the upper body panels, left and right both in front and rear; the left and right lower body panels; the door posts; the cabin roof panel; and the doghouse pieces, front and rear. (The doghouse is the box-like structure on top of the ship that surrounds the main shaft.)
Each of these pieces has joggles and overlapping sections, each held together by either screws and nut plates or Dzus fasteners. What the heck is a Dzus fastener? Look at the pictures. Dzus buttons are the large, nickel-size circles with screw driver slots on top. These types of fasteners are used on access doors or pieces of aircraft that can be opened or removed with the turn of a large screw driver, Dzus driver or even a coin.
A spring wire is riveted to the inside of the opposite piece of material that the Dzus button locks onto. On our particular aircraft, the other pieces of the body that don’t come apart regularly are held together with machine screws and nut plates.
And this is another tool that you will really want when working on the 162F: an electric screw driver or drill motor with a Phillips head bit. There are a lot of screws and nut plates on this helicopter, and you’ll end up getting carpel tunnel syndrome trying to take all these things in and out without a lazy man’s screw driver! Try to find a driver with a clutch while you’re at it. With this, you’ll avoid scrunching gel coat on the fiberglass pieces.
While assembling the body, follow the instructions in the manual closely. The step-by-step documentation in this area of the kit is particularly good. If you don’t have the tailboom mounted, you won’t be able to completely finish the body panel installation. The four body panels in the rear surround the tailboom, and you’ll have no way of telling now much to trim for clearance. Just assemble all the pieces and put together only the top joggle using a couple of Clecos.
The bottom will have to wait until you have the boom mounted, as well as the fan shroud and heat shielding. As you mount each fiberglass piece and fit the thing together, trim. But be conservative. You can always cut more, but you can never go back. Once you get all the main body pieces together, the cabin roof panel should be mounted, then the door posts.
That Big Thing Up Front
Now comes the biggest pain in the body installation: the windscreen. Use a friend to help you at this point to avoid dropping the dang thing.
And be especially careful with the windscreen if you’re working in a cold environment! It’s made of Plexiglas, and when really chilled, if flexed too far or dropped, it will crack or break. (You don’t have to be quite as careful if it’s warm where you’re working.)
Once the windscreen is mounted and supported by all its screws, however, it’s a significant and strong piece of the body. I’ve never heard of any RotorWay windscreen that hasn’t needed trimming, by the way. They are purposefully manufactured over size because body assembly and piece placement varies from builder to builder. I’ve found that the easiest way to trim the screen, as well as any of the fiberglass pieces, is with a hand grinder using a thin carbonite metal cutoff disk. For smaller areas, using a Dremel or Moto-tool with those wafer-like carbonite cutoff disks works wonders as well. Used correctly, either of these will cut through the materials almost like butter, with nice looking results. Wear eye protection!
There’s a protective plastic coating on both sides of all the transparent pieces in the kit, and there’s no reason to remove the stuff until you’re ready for final installation. Minor scratches can of course be removed with Mirror Glaze.
The windscreen is supported every 3 inches or so by 6/32 machine screws, washers and nuts. These holes should be the absolute last thing you locate and drill when installing the body. Just like everything else, start with 1/8-inch holes using Clecos and drill to size later. You must be very careful when drilling this material with a standard bit to avoid cracking the windscreen. Again: A warm environment is your friend here, and so is the uni-bit.
Later we’ll glue the 1-inch fiberglass strip around the windshield and then drill the holes slightly oversize and install all the screws with the nuts just slightly snug, almost loose. This looseness allows for typical helicopter vibration, and it avoids a cracked windscreen. The “loose” screws support but don’t hold everything too tightly.
In the unlikely event that you do get a crack, it can of course be stop-drilled with 1/16-inch holes at the ends of the cracks. (My apologies to those who already know all these basic construction notes.) As a point of information, with my two other earlier RotorWay helicopters having logged approximately 400 hours on both, I’ve yet to crack a windscreen. So from my standpoint, I’ve found this to be a good setup with the existing materials.
Did you know the 162F windscreen is slightly tinted gray? Pretty nice.
Now mount the eyebrow windows. You have to trim the window to fit and then drill a few holes: It’s a no-brainer. You locate approximately eight screws and then if you want, paint an edge border. These windows were a great addition to the Exec 90 and now the 162F, for practical purposes as well as aesthetically. As a side note, I didn’t go with any edge paint simply for simplicity, and it’s one less thing to scratch. The only trouble with no paint on the edges is that dirt tends to accumulate where you can see though, between the window and the fiberglass joggle area. Do what you want.Final Body Adjustments Once all the body panels, windscreen and windows are located, and before you drill any more holes, you’ll want to step back and look at your creation, making sure the giant egg looks like it’s hanging straight on the ship. Look from the front, but especially from the rear in relation to the landing gear.
If it’s hanging crooked, minor adjustments in one or two panels can do wonders for the entire structure. You’ll also need to check a few places in the ship for clearance of other components. When installing the doghouse per the plans, you should make sure the collective rod and the swashplate components all clear the doghouse. If they don’t, you need to adjust the doghouse location slightly.
Make sure you check for clearance while moving each control through its entire range of travel, and while you turn the rotating swashplate. Look also at the battery box weldment’s corners and how close they come to the tub. In my case, I had to grind off a corner to keep the tub from rubbing.
I’ll also glue a piece of rubber to the tub in that area since in flight and over time, the body tends to shift and move a little, and I wouldn’t want any unseen chafing! After installing all the hoses and electrical lines, chafe avoidance is a big part of preventative maintenance!
We’ll get into some tips on that when we install the fuel and coolant systems. At some point in this process you’ll need to sand down the edges of all the body pieces. I wouldn’t bother doing it until you’ve finished fitting everything due to the fact that you’ll first be doing edge trimming on a few of the pieces.
Those Panel Fasteners
After everything looks good and you’re happy with the fit, you’ve come to the ever-dubious task of laying out the nut plate and Dzus button placement. This is one of those areas that the more time you take and the more careful you are, the more professional your ship will look.
Making an edge guide for drilling helps a great deal as it will keep each of your nut plates and Dzus buttons a uniform distance from the edges. (Make sure you finished all your edge trimming first!) Now you need to take all the fiberglass pieces apart and wet-sand the gel coat, readying for your paint scheme.
Some guys paint the ship with all the pieces apart; some do it with the thing together. I suggest a combination of the two: Disassemble the body and put your base coat color on each piece separately. Then put it all back together and lay out your design. As there are so many pieces–and depending on how complicated your scheme–it’s much easier to paint the lines and detail with it together so that everything will line up when assembled. This of course is all personal preference, and everyone has his or her own opinions and procedures.
Also, contrary to RotorWay’s plans, I would wait to paint the ship until the very last because at this point in construction, you’re still going to be disassembling the body many times for various reasons, and believe me, you don’t want to worry about scratching anything as it goes together and comes apart so often.
Besides, over the year or however long it takes you to build, you’ll change your mind about how you want the ship to look! As I did the last time, and as fellow builder Mike Sherick did on his current ship, both of us choose not to finish our paint jobs until after flight testing and until all the bugs had been worked out of the ship.
Why? Same reason: We were able to concentrate on the much more important aspect of getting it flying safely and correctly first; then we made it look good. I’ll do the same on this bird.
On the other hand, I think Mike is having too much fun flying, because as of this writing, he has put 75 hours plus on the ship and it’s still a generic white! By the way, that looks pretty dang good!
Two last notes on the finish: Paint conservatively and don’t use too much! Just like the frame, a primer coat is really not needed and only adds weight.
Remember that light colors make the ship look bigger, and light colors fight the heat. If you’re in a warm or hot environment, this is definitely something to consider. Heat is your enemy with this ship, and though the liquid cooling system does a good job, every degree cooler helps with power efficiency, and who wants to fly in a hot cabin!?
We’ve concluded one major but not-so-tough step in the construction of our 162F now. It’s at this point that you should invite the neighbors and have them take a look. The shell looks pretty impressive sitting there on the frame! Take a lot of pictures and document everything! You’ll want to look back at it all and remember each step of fun, but you also need the documentation for a meticulous FAA inspector!
Thanks again for reading, and be sure to pick up the next issue where we’ll install all the controls!
FOR MORE INFORMATION on the RotorWay International kit helicopter, contact the company at 4140 W. Mercury Way, Chandler, AZ 85226; call 602/961-1001; fax 602/961-1514; www.rotorway.com.