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I decided to complete as much work as possible on the body at this early stage. GRP work generates dust - lots of it, and it gets everywhere. The Rotor head and essential control parts are in place only because they could cause potential body clearance issues. This section will probably seem a confusing jumble to any non-Exec owners or anyone who hasn’t yet reached this stage (heck - it’s still confusing to me!) but with the panels in you sweaty mits, all will become clear.
I used six basic tools when working on the body fit -A good quality steel tape measure, a metre-long straight edge, a 4 foot spirit level, a well balanced plumb-bob and my own two eyes. Simply standing and staring at the ship really is the best way to perfect the shape. If it looks wrong – it usually is wrong.
I used the Video, the Assembly Manual and the guide Cleko holes as a rough starting point but things soon got moved around. I recommend that you spend a few days just playing with the panels before drilling and fixing too much but don’t be afraid of adding a few more Cleko holes - you can always fill them up later if they’re in the wrong place.
Much has been written about assembling Exec body panels on Owners Forums and personal web sites. Before I launched into the job I made some basic assumptions. Once upon a time someone at Rotorway made the first body buck. From the general quality of the mouldings I assumed that the original Exec buck had been pretty-much symmetrical and accurately made. I know that many owners have made superb jobs of putting these ships together without too much hassle and I’d seen some nicely built examples but from my first sighting I began planning improvements and modifications.
The biggest headache is finding a datum to start from - there isn’t one. A datum is a component or a fit between two parts that is obvious, fixed and whose position can be in no doubt. Fitting the body parts to the chassis of a Foreman Mk4 (the car we manufacture) poses a similar challenge except that the car’s windscreen is made from laminated glass and you cannot change it’s shape or size. This is the car’s starting datum and the fit of the remaining body panels is based around it. On the Rotorway however, every panel is flexible and every panel’s shape can be changed – including the screen.
Trimming the cut-outs for the four landing gear poses the first of many dilemmas. You should really fit all the body panels and have it all perfectly aligned before cutting the LG holes but you can’t fit the tub until you cut the holes. Hmmm.The outline pre-marked on the panels by Rotorway is way-out so I cut them as small as possible at first, measuring and marking carefully from the landing gear.
In the search for a Datum, I figured it was safe to assume that the four panels on each side of the ship should form a perfect cross with 90 degrees corners and the Dog House join should be parallel and in line vertically. I took and compared several measuremants on each side.
For instance, from the front edge of the side panel join at the door opening down at an angle to the base of the screen support pillar where it joins the tub and the height of the panel joints from the ground. I hung a plumb bob from the side of the panel near the the eyebrow windows down to the seat panel and measured the distance in from the side of the tub. I held a straight edge vertically against the side of the body in the area of the seat back - is it concave, flat or convex? I discovered that it’s not always safe to assume that all the panels need to be trimmed to size - they may have been already trimmed undersize and could require extending or building up with new GRP.
Here’s the plumb bob, suspended from the body edge above. It hung approximately 1 1/4 inches inboard from each side
If you’re at this stage of the build, with all the body panels fitted except the main screen, stand facing the front of the ship, six feet from the centre, close one eye and line up the moulding seam on the top of the instrument pod with the centre of the seats - measure and mark a line down the seat back if necessary. Gaze up at the roof line. Does it look lop-sided?
Try holding a four-foot spirit level under the front ends of the side panels in front of the eyebrow windows. Is it horizontal? Again use your spirit level across the front of the seat moulding. Try not to stress the panels and force them into position. Rather let them rest naturally, look at the shape then see what can be done to fix or improve it. For the record, I cut approximately 3/4 inch from the bottom edge of the screen and, from the pilots side, a piece tapering from 3/4 inch at the bottom to nothing at the top.
In the pictures and captions are a few of the ideas I came up with, and a few I borrowed from other builders.
If I leaned gently on the instrument pod I found that the whole floor pan would spring around 1/4 inch up and down on the outer rubber support feet. A few layers of GRP reinforcement in the corners sorted the problem. The row of screws that fix the forward edge of the tub to the floor pan came uncomfortably close to the edge of the panel so I reinforced and extended the lower edge by 1/4 inch with new GRP
With the panels Cleko’d tight to the seat back I had a concave shape at this join - not good
Here’s the gap between the seat back and the pilots side main body with the panels sitting naturally. This is probably due to the seat back panel shrinking in the mould.
To correct the concave panel problem meant, in effect, widening the seat panel by around 1/2 inch on passengers side and 3/8 inch on pilots side.I split the seat back from top to bottom on each side with a panel saw. I cut through the outer slice near the middle and notched the top edge with the saw blade at 1 inch intervals along its length. I drilled and Cleko’d the split outer slice then ‘V’d the edges of the saw line inside and out with a Powerfile.
Here I re-glassed the two pieces back together inside and out. I’ve now got slightly wider seat sides but my panels are a pleasing gentle convex shape. This process has the added benefits of increasing elbow room slightly, creating more clearance for around the fuel tanks and correcting the common problem of a gap at the rear of the doors.
There’s also a natural dog-leg along the side of the passenger’s floorpan where the screen support pillar joins. I used the same split and rebuild method to correct the shape.
The tub ended up uncomfortably close to the battery tray so Matthew moulded a GRP dome from a childs plastic ball and bonded it into a hole cut in the tub.
The upper side panels touched the seat back only at two points - 1 the crease at neck height and 2 - at the vertical flange of the upper side panel where the roof panel joins. In between was a crescent-shaped gap of up to 3/8 inch. In addition to this problem, the angle of the return flange on the seat back was 20 degrees out of parallel with the side panel. I cut away most of the return flange completely on both sides, made a few saw cuts down through the remaining few inches and ground away the thickness of the material on the corner so the remaining returns could be easily pulled in to the correct angle with Clekos. I stuck packing tape to the inside of the upper panel to act as mould release and laid up GRP to form a new flange and reinforce what remained of the old one.
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It’s a bit difficult to make out but here is the finished, corrected upper seat back flange painted black. So, all the body panels now sit flush to the seat back, the nut plates are all perfectly square to the panels surfaces and nothing is under any stress or tension.
I ended up with 1/4 inch of packing between the pilots side curved frame and the seat moulding. This started as two pieces of 1/8 in rubber that was eventually replaced with a bed of ’Fibrefill’. This is a gloopy fibrous resin filler that body shops use to bridge rusty holes in cars. I don’t know what the US equivalent is called.
I first drilled all the mounting holes through the seat and the frame then wrapped the frame tubes with packing tape as a mould release and laid a sausage of filbe fill on the frame tube and lowered the seat into position. I also filled the gaps between the seat back and the cross tube, ( a mucky job by hand).
Here’s the pilots seat bottom. You can just see the built up mounds of fiberfill where the moulding will fit against the frame tubes, dressed off to the minimum size.We now have a perfect and hopefully squeak-free fit between seat and frame
Rotorway recommend making a small aluminium doubler plate to join the two aluminium seat back access panels. I chose an alternative method. Forming a joggle along the bottom edge of the upper panels strengthens the panel and makes a neater job of the join. This is a regular body shop joggling tool.
Here’s the cabin air distribution moulding fitted to the underside of the footwell panel. I rubbed down the mating flanges until I’d achieved a good mating fit then bonded the two together with regular body filler. This makes a strong, neat, airtight join.
I made the air outlet holes a little longer then recommended but I left a web in the middle of each.
I fitted the Rotorway Storage Compartment in the passengers footwell but I mounted it underneath the panel instead of on top as recommmended. I installed thirteen M4 Rivnuts in the flange of the storage moulding and secured the moulding in place with countersunk stainless steel screws from above including three through the hinge. If you’re fitting one of these make sure to install it well foward to clear the front landing gear below.
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