Chronicling my Long EZ construction (and a few other things).
Disclaimer
This blog is for entertainment purposes only, and is not meant to teach you how to build anything. The author is not responsible for any accident, injury, or loss that occurs as a result of reading this blog. Read this blog at your own risk.
Ok, I admit it! This was totally lazy and unnecessary, but I had the time and the tools, and I like to avoid sanding wherever I can.
The problem is that the doubler that goes on the aft face of F22, needs to be cut (or sanded) at an undetermined shallow angle.
Using a caliper, I measured the thickness of the foam (6.87mm), and the length of the base of the ramp (26.39mm). With that, all I had to do is the inverse tangent of 6.87/26.39, and got the angle 14.6˚.
Section C-C is what we are interested in.
Then I set the angle on my table saw...
... and committed to the cut.
The result turned out very well, and required no sanding at all.
I decided to economize on this expensive foam, by cutting F28 out of leftover foam from the leg cutouts. Since my parts are already a little bigger than the plans, I don’t want to end up short by wasting good foam.
In the manual, the foam cutting plan shows F28 cut out of two half pieces.
Foam panels cutting plan
Although it would have been easier, and quicker to cut F28 out of a single piece of foam, I followed the manual, and plan to rejoin them soon using wet-micro before glassing.
F28 is 2" wider, and 1" taller (in the middle) than plans to match the taller/wider instrument panel
Due to the foam density, cutting this kind of foam with a razor knife is a slow process. It does feel more like cutting through Balsa wood than a piece of foam, really.
The slow speed made for a more accurate cut though, and pretty soon the all remaining foam bulkheads were completed.
The bulkhead named F22 is a very important structural member that will eventually support the Canard (horizontal stabilizer - aka front wing). Two bolts will attach it to F22, and two pins (bolts with the head ground off) will secure it to F28.
Mike Beasley's Long EZ
Walter Grantz Long EZ
F22 instructions (like the instrument panel) come in the form of a scale drawing that needs to be reproduced accurately.
In Ch. 4 - Instrument panel - Part 1, I devised a method for transferring the scaled drawings to the foam. Although I’m surely not the first one to use it, no one told me about it, so I will claim it as a discovery and use it again here.
The one difference this time is that, because the F22 drawing is symmetrical about a vertical line, the plans only draw the right half of it, and it’s up to the builder to replicate the other side.
Tracing right half of F22
Using tracing paper turned out to be an excellent choice once again. I first drew the right side.
Then I flipped the tracing paper over, and repeated the same drawing on the back side of the unused portion of the sheet. Because of the semitransparent nature of tracing paper, the drawing appeared like it was done on the same surface, and it was ready for use.
Once again, I poked holes through the paper and into the foam with a paperclip to transfer key intersections from paper to foam, then connected the dots (holes) with a pen.
The result was an accurate reproduction of F22 onto the foam, and because this type of foam is pretty expensive ($105 for a panel), I also drew a required doubler for F22 on the same panel. I will use the remaining foam for F28 as well.
I wanted to expand a little on one reason why I think it is important to obtain an original set of plans, besides the legality argument.
Early in my search, I responded to a barnstormer.com ad for a set of Long EZ plans. The price was a little low, but talking to the seller he reassured me that these plans were original.
Online ad for the set of questionable plans I originally purchased
The plans I received were pretty good, but there were quite a few inconsistencies that screamed "Scam!" as soon as I got a closer look at them.
The most obvious was the paper. You’d imagine 30 year old plans to be a bit yellowish and oxidized, but these were an immaculate white, like they were fresh off the press.
Comparing a fake to an original
Later, when I noticed the darker markings made by photocopying over the rectangular holes for the binder fingers, the jig was up.
Notice the dark rectangles, they are the photocopy of the holes in the original manual.
To make a long story short, I eventually got my money back, but this is still not the moral of the story.
I decided to compare the scale drawings I had acquired, with a known set of Long EZ plans, and I was surprised by what I found. The very critical wing section profile drawings had been stretched asymmetrically during the copying process, and were at the very least unusable trash, and at worst unsafe. Actually, all the scale drawings exhibited this deformation to varying extents.
Overlaying fake and original scale plans. This is the top left quarter of one page and you can already see a mismatch.
Bottom left quarter of the same page. The mismatch is enormous.
Bottom right quarter of the page. Obviously the stretching happened only in height, as features still match up horizontally.
Bottom left of the instrument panel
Bottom right of the instrument panel, stretched horizontally and vertically by different amounts.
F22 Bulkhead
So, the moral of the story is: “Buyer beware!” You might spend tens of thousands of dollars building a plane that might kill you, just to save a few hundred bucks up front.
If you did purchase an original unused set, you should have a registration page (top half of plans page 1-4) with the assigned serial number, and at least a note on the back where the rights to this number are signed over to you by the original buyer.
Registration with serial number, Sally Melvill signature, and rights release on the back.
Do the right thing, find and purchase a genuine unused set while there are still a few out there.
I tackled the back side of the instrument panel with the help of my daughter.
Micro-slurried the foam first, as usual.
The last of the three fiberglass layers is supposed to cover only above the leg cutout. I decided to lay it first instead, so that the ragged edge would be covered by the two full size layers.
The next two layers went on easily.
Peel-ply was applied anywhere a secondary bonding is planned (or suspected).
The instrument panel will be attached to the sides, and bottom of the fuselage, so I peel-plied the whole perimeter. Since the lower half of the panel will also connect to the side panels, more peel-ply went on there.
I kept the temperature of the shop at 80℉ until the next day, then I shut the heater off, and tried to keep the panel temperature up by using 1400W work lights. The instrument panel felt uniformly warm, and was never hot to the touch. Two thermometers confirmed that the temperature remained at a constant 82℉, even while the shop was allowed to cool down to 70℉.
The next day, my vibrating cutter made quick work out of trimming the edges of the cured panel.
Thus far, we have been working with flat, andrelatively thin pieces of foam. We have had to do some minor shaping with a knife, and sandpaper, but have not had to deal with the thick foam blocks that will become wings, winglets, canard, and control surfaces.
As you might imagine, these aerodynamically significant parts require a level of accuracy that is beyond what is possible working with such primitive tools. To our benefit, the designer has once again devised a simple yet ingenious method of achieving the precise shaping of these parts, with inexpensive home-made tools.
It turns out that the foam selected for this purpose (PVC) can be easily cut using a hot metal wire (nichrome). What is even more significant from a health standpoint, is that it does so safely. This is an important point to be made, because Urethane foam will also cut with a hot-wire, but will release hazardous gasses in the process.
Hot-wiring PVC = Good
Hot-wiring Urethane = BAD!!!
The hot-wire tool consists of a 2”x4” piece of wood 3 to 6 feet long, through which two holes are drilled, and two short pipes inserted. The wire stretches from the ends of the pipes, and can be tightened by twisting one pipe. Clamps attached to the base of the pipes provide electricity to the wire, which heats up and is then used to cut the foam. The power supply can also be homebuilt using a transformer and a dimmer.
Hot-wire cutter sketch
My setup for cutting small blocks of foam
So, we have a hot-wire. Now what?
More importantly, the hot-wire will enable us to make precise cuts of what?
This is where Burt Rutan provides his expertise in the form of paper templates. These templates need to be reproduced accurately onto some stronger material (usually wood laminate).
Canard template (not to scale)
They later get nailed at both ends of a block of foam, and the hot-wire is made to slide over the profile of the template, thus yielding our airplane part.
Canard templates (one on each side of the foam) nailed to foam block
One benefit of this method is that advantageous features, such as wing taper, twist, and smooth profile transition, can easily be reproduced to improve the aerodynamic efficiency of the part, in a way that is almost impossible to duplicate with any other form of airplane-building, at least on a budget and in a non-factory setting.
To prove this point I will share a video of my wife Gina, and my friend Mike, cutting a block of foam with a hot-wire. The width of the piece is not important, as this was just an exercise, yet the profile is an accurate reproduction of the Long EZ canard because they used the actual canard templates.
Worthy of mention, is the fact that Gina had never seen this process done before, and was blissfully watching TV before being summoned in the shop with a ruse. She had no previous knowledge, and received no instructions besides what you see on the video, and all she wanted was to get back to her show. Against all these odds, I have to admit that she did a great job, and showed us all that hot-wiring is not as difficult as you might imagine.
The construction manual encourages the use of leftover BID pieces on the forward side of the instrument panel (with proper 1” overlap, of course). It also states that BID orientation is not important.
I decided to use up some of my scrap BID, and continue laying it at a 45˚ bias (main fiber orientation).
Testing scraps of bid for fit over foam panel
After designing my fiberglass pattern (above) with plenty of overlap, I carefully rolled the pieces, and laid them aside in the order they would be used.
Fiberglass ready to go
With the foam panel properly covered in slurry, I placed the BID in accordance with my schedule, and added epoxy.
This is the fun part of the construction, but also incredibly messy if one is not careful. As you can see, plastic sheeting on the table is a must, as the warm epoxy is very runny.
With the first piece in position, and properly saturated, on went the second piece...
... and the third, and the fourth.
As I’ve done previously with all second layers, I elected to cut a whole new piece of BID to cover the entire panel.
At about this time my good neighbor Lou showed up, and was promptly put to work. Epoxy mixing duty at first, but later he got some hands-on time laying the third ply. This ply covers only the top half of the panel, and since Lou did such a good job there, he was also drafted to peel-ply where needed.
Mixing some epoxy for starving peel-ply
The instrument panel backside turned out quite nicely.
The best part is that I might have found a capable assistant who only lives two doors down from me.
I’ll be knocking on your door soon Lou, thanks for your help.
