Ch. 4 - F22 - Part 5

F22 glassing - front side (10.4 hrs)

Glassing the front side of F22 has been something I both looked forward to, and dreaded. You see, the layups are getting more complicated as the building process continues, and here we have the first big (as in thick) structural layup.

The main layup is the usual 2 plies of BID over the entire surface, but both edges require 9 additional plies of alternating UNI and BID. 

Since I needed 8 pieces of BID (at 45˚), and 10 of UNI (at 0˚), I fashioned a slightly oversized cardboard pattern to help with the repetitive cutting task.

Cloth cutting pattern

Actually I made two, so that I could cut a big rectangular piece first, and then split it into two.

BID getting cut at 45˚

UNI getting cut at 0˚

Once the fiberglass was cut, I was ready to roll.

Having everything ready before mixing epoxy is a must!

I mixed a small batch of pure epoxy, added glass micro-balloons, and applied it to the foam. Then I added more micro-balloons into the mixing cup until it reached a frosting consistency, and with it I patched a few nicks and gouges I had caused earlier, while trimming the back side. 

This time I decided to use a slightly different technique for wetting the fiberglass. Normally I’d just pour the pure epoxy over the cloth, and “go to town” with the squeegee. But working on the back side previously, I had some issues with weave disruption in the very narrow sides of this bulkhead. In essence, using more pressure with the squeegee trying to work the excess epoxy out of the material, resulted in dragging the cloth along, due to the small wet cloth surface in contact with the foam. So, I put a piece of plastic sheet (cut from the end of the work table) over the cloth, and used the squeegee over it.

Plastic film technique

This technique worked so well that I ended up using the same piece of plastic film repeatedly all over F22.

With the first layer completed...

Rough looking, but showing generous (> 1") overlap.

... I added the second layer, and since I had used up all of my BID scraps, I had to use a whole new piece of cloth.

Now, up until this point we didn't do anything we hadn’t already seen before, but this where norm gives way to new, and recycling the same piece of plastic film, I started adding the 9 alternating layers of UNI and BID.

First layer of UNI reinforcement being added to F22

Eventually one side was finished and peel-plied...

Dark brown area is the 9 layers of reinforcement 

.. then I started the other side...

and eventually finished that too.

Working time until now was already over 6 hours!

At this point, I let F22 cure for 24 hours in the heated shop, which has become the warmest place in the house this winter, and my favorite hangout.

The next day, with the fiberglass as hard as a rock, and after drawing some blood from the sharp edges, I flipped the piece over...

Back side showing

... cut off the excess...

... and finally F22 was completed.

Before trimming, I lifted the top edges of the peel-ply to aid in its removal later.

Below, I wanted to add a few close-ups to highlight some of the details of this odd looking bulkhead.

Ch. 4 - F22 - Part 4

F-22 glassing - back side (4.6 hrs)

Once again the plan calls for reusing leftover BID pieces for F-22, with appropriate overlap, so I gathered all my remnants and went to work as usual.

I slurried the foam piece...

... glassed it, making sure to leave 1” or more of overlap between cloth pieces...

... slurried and pressed the doubler into position on F22, glassed it, scissor trimmed it and peel-plied it.

I added a strip of plastic over the doubler to prevent it from sticking to my “load distribution device” (aka flat piece of leftover wood) and applied constant pressure by means of weights. Finally, I let the piece cure for 24 hrs at a shop temperature of 80℉. 

The next day I removed the weights and the plastic...

... and got started trimming the excess fiberglass with my vibrating cutter...

After a little sanding, the finished piece (back side only) emerged, ready for a photo op.

My nephew holding F-22 (and a slice of pizza). Peel-ply was marked, reminding me to remove it before final assembly.

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.