Ch. 4 - F22 - Part 3

F22’s doubler (0.2 hrs)

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.

You’ve got to love math!

Ch. 4 - F22 - Part 2

F22 and F28  (3.2 hrs)

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.

Ch. 4 - F22 - Part 1

F22 (3.3 hrs)

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.

F22 on left (blue), doubler on right (red)

The plans - Part 2

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.

Ch. 4 - Instrument panel - Part 3

Instrument panel (2.3 hrs)

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.