Non Build Mods

Paint Adhesion Promoter

Date:  04-22-2022
Number of Hours:  1
Manual Reference:  no ref

This plane is getting a nose job, or to be more precise some very special artwork airbrushed onto the nose area.

The usual method when adding paint to an already painted surface is to sand or scotchbrite the area first. Adhesion promoter was suggested by the professional painter who did the primer and topcoat work on my plane. He uses a Boeing product for prep when art or sign work is added to a finished business jet.

Stacy Lourens, a Melbourne artist is going the airbrush work on my build and wanted to test products. I was reluctant to sand my freshly painted plane if an aerosol can would do the job instead.

Stacy can also be found on Facebook as well as the above Instagram link.

Here’s what we tried. The Raptor can is under $30 at a local automotive shop. The AP-1 is the Boeing product that costs way more than it should in Australia. The board they are sitting on is a test piece I used earlier when playing unsuccessfully with roll on paints.

I divided the board long ways into three. The middle section was dulled with Maroon or Red Scotchbrite  This is in the 320-400 range although it depends too on how hard you press. The two outer sections were to be sprayed with one or other of the cans.

As you can see, Stacy has done a very beautiful feather. What happens next is a bit ugly…

Yes clicking the picture will send you to the video of the test. The bottom line is that I’m going to have to sand or dull the nose for Stacy’s artwork. He uses a water-based paint and testing proves its going to really stick well in the sanded area.

Just to add data to this test, an intercoat was used over the left vertical half of of the board about 15mts after the artwork. The intercoat had 30-40minutes to dry before the tape and scratch testing. The bottom line is that although this gave an improved result, the scotchbrite still wins for this nose section.

I am doing vinyl wrap items on the tails and for the registration marks (VH-XEZ). I will use one of the promoters for those. For the nose, its old school sanding as Stacy originally wanted. We did the science, a proper experiment, and I’m writing it here to make it real.

 

 

 

How to Cut Braided Flexible Stainless Pipe

Date:  08-06-2018
Number of Hours:  1
Manual Reference:  no ref

I have braided pipe that needs a clean cut. I found this method on a YouTube video.

Use a wide cable tie next to where you want to make your cut.

Get an angle grinder with a cutoff wheel and make the cut next to the cable tie.

Remove the cable tie and you have a pretty clean cut with out all the braided wire coming apart. Nice.

How to Install a Wing (Wing Bolt Orientation)

Date:  04-08-2018
Number of Hours:  1
Manual Reference:  no ref

The three wing bolts (AN8-22A) can go bolt side in the spar or the bolts through the wings and of course nuts on the opposite sides. What to do?

You need two 3/4 socket heads. Then the combination at the top for the wing side cavities because the opening is not at a good angle for tools.

The rotating socket spanner is really good for holding the inboard upper side nut which is accessed through the hole at the underneath side of the spar box. (don’t forget to use washers both sides)

This trick works really well for seeing what you are doing inside the spar box when putting on nuts or feeding through a bolt.

This is how I tighten a nut on the upper wing. Note I’m saying a nut on this side. The other two nuts go on the spar box side.

Here’s where the bolt goes on the inboard part.

Summary

We have 3 nuts and 3 bolts to hold on the wings.
When installing the wing:-

OUTBOARD two holes one on top of the other
1. Top Bolt goes through the spar
2. Bottom bolt goes through the wing

INBOARD one hole
– accessed through the spar by getting in the back seat and the other side with the cowls off at the wing root
3. Bolt goes through the wing (this means you thread the nut on from the back seat in the spar position)

Please let me know if you have a better way of doing this.

An F16 Style Air Scoop for JZE

Date:  12-14-2011
Number of Hours:  50
Manual Reference:  no ref

My Long-EZ overheated and the reason was that it was not getting enough cooling air to the cylinders. When I bought the plane I was told that the one CHT temperature sensor was on the hottest cylinder after careful testing by the builder. I always had good temps yet the plane before I got it kept having heat related issues in the cylinders which I could see in the engine log book. In that tradition I had my own problems too.

I finally got to the bottom of these recurring problems. The heat sensor was on cylinder #1. This is almost always the coolest on these pusher planes. The hot one is almost always #4 and thats where the most trouble was. Eventually I put in a JPI engine monitor and made a new air scoop. The scoop was a huge job. In retrospect I should have put in the new monitor and then rebuilt the lips of the scoop and see what that did first.

That’s with the knowledge I have now. Then I just went whole hog!  Here are some notes I took at the time on building this Duct. I’m calling it a change from the plans P51 style to an F16 style.

I got a lot of advice and help from Terry Schubert and Rim Riggs. There is also a good article in the CSA Issue 85 page 8 by Kurt Wegge who replaced his original scoop. My thanks to these people for there generous gift of time and knowledge.

BUILDING an F-16 DUCT

Scoop or Duct  has 11 degrees included sloping sides 5.5 degrees per side.
I first got a profile of an F16 duct from Russian website (not sure how important the opening shape is however I needed to get my hand in to to get to the gascolator for a daily fuel drain.

Above is the pic I found of a scoop and below after playing in Photoshop. Not very scientific I know.

  • Draw out on to graph paper and count the squares to work out opening size.
    Use Photoshop to expand printed image until the scoop is the desired opening
  • Old plans P-51 was 35sq”Desired was 16 to 17”. I choose 19.1sq” in the end for a bit of safety margin. A smaller duct can be made at another time if necessary.
  • We need to find the opening size of the expanded end and what distance it is on a 5.5degree slope. We also need to have the opening expand by at least twice. Three times is better. Then we have our expanded high pressure air.
  • Draw out a straight line on paper. Then we need a triangle with 5.5degrees at the pointy end and a right angle at the other end.  Use sin(5.5) to work out our dimensions.
    Sin X length (l) = height (ht)    ht = radius / sin(5.5)
    intake 3.4” at the highest point of the scoop shape (1.7” radius) = 19.28 sq”
    firewall 5.7” (2.85” radius) = 54 sq”   This is X 2.8 expansion
    length = ht / sin(5.5)
  • Draw out the triangle on paper using the length as the vertical upright and once two lengths are known at a given distance apart then projections can be made in-between for a shorter or longer duct.
    Once the diameter of the larger opening is worked out. Use Photoshop to expand a pic of the duct until it has the right diameter on a print out.
    Confirm area by printing on graph paper and counting the squares (partial square count as half)
  • Make two templates using plywood or Masonite or similar. Strong, but not too thick.
    They need to be exactly centered on a block of blue foam and nice and straight the exact required distance apart (length of the foam block adjusted to suit)
  • Then cut away the foam and use a straight edge between the templates to form a perfect inner plug for the inside of our duct. This is the bit we want smooth and correct. The outside dimensions need only be for conforming with minimum drag to the airframe and for having a straight duct.
  • 10 mm divinycell thermo formed and microed to the outside works well.
    Place the plug on a holder so that two layers of bid can be layed up on the outside of the solid plug. Use plenty of wax and a release like hairspray or PVA (if you have a spray). Peel ply all of it for a smooth interior of the duct.
  • Leave it on the plug while you form the outside foam (must be fuel resistant) urethane of some type. You could use tape or rope to form the foam around the laid up plug, it takes a bit of heat to round the divinycell. It can be done in strips or maybe 4 pieces. Anyway you like as its not critical, its to make a cored part that is light and strong. You already have the correct inner shape.
  • After the foam is microed on. Clean it up and lay up two plies of bid (45 degree of course) over the out side. Once cured you can gently remove the inner plug. It should come out in one piece and a very thin knife slid down the sides upper and lower should do the trick.

Here are 47 pictures of what I did. If you are contemplating this I am positive there are better and easier ways!


 

 

‘RAM’ Airbox Building

Date:  11-09-2011
Number of Hours:  50
Manual Reference:  no ref

Way back in 2011, my flying aircraft, a Long-EZ, overheated after some engine mods and this needed addressing. I had put in a large air scoop to replace the plans air filter that sits on the firewall. I wanted direct air as this I had read can give an extra 60-80 static revs. Who wouldn’t want that? The problem was that the scoop I choose, which was a sort of ‘off the shelf’ item for an EZ blocked a lot of the cooling air to my cylinders.

I needed a smaller footprint!  So I had a go at making my own box. I wasn’t quite sure how to do it and the design evolved as I made it. I did know that a minimal foot print was the goal and something that I could put an air filter on.   I have 79 pictures below to show the process from start to finish.

Almost every step was something new for me. I had done the Chapter 3 education in the Long-EZ plans but that was about the extent of my experience then. Shortly after this I started building the new Long-EZ from scratch, I think the process of this little project helped my confidence to have a go at the crazy big project.

You might ask did this box thing work? Yes, I did achieve a measurable 60rpm static improvement.

After a few years the inserts for the hinge pins were getting oversized or rather oval and loose due to air frame vibrations. I found some bronze inserts in the Aircraft Spruce catalog just the right size, cut the old ones out and floxed in the new. So far so good.

Most of the silver paint has come off. There is a bit of oil and sometimes fuel in that area. If I was doing it again I might use a proven fuel safe epoxy. I think I used MGS in this case and it seems fine so far. I have well over 500 hours on this box now and might do something similar if I had to a second time. Hopefully I could buy something off the shelf, this was a lot of work but very educational at the time.

Here’s the first pic which shows that I have made a mock up to get the pipe angle right. The pipe has to point into the middle of the P51 plans style air intake and there needed to be room for the pipes to go on. I used a hinge as you can see that I could tighten and then gaffer tape of course.  I don’t think I need to say anymore the pictures that follow tell the story.


 

 

 

 

Flox PVC to Aluminium Test

Date:  05-22-2017
Number of Hours:  2
Manual Reference:  no ref

I needed to make a viewing port in my common sump by bonding 6mm PVC to 2024 T3 aluminium.

Does it stick? I make up a test piece as you see in pic 1. I am using EZ epoxy. The PVC is 6mm thick, I routed a 3mm step into it and primed with a commercial PVC primer which is really MEK and acetone combined. I roughened the aluminium surface with 40 grit sandpaper and cleaned with acetone.

I painted the surfaces with pure epoxy and then mixed up flox. I bonded the two surfaces, clamped them and left for two days to cure.

Pic 2 shows that I have put the joined pieces in a vice and hooked a weight measure device on the PVC and applied a shear force to try and break the bond at the weakest point.

At between 20 and 25lbs I was bending the .080″ 2024 and still the join held! I measured up to 26.5lbs which took a lot of fulling force. Somewhere between this and 30lbs the join failed.

That is seriously strong! Pic 3 shows that the join failed cleanly at the glue line. I also noted that a bit of glue that squeezed out onto un-sanded aluminium and unprimed PVC failed very cleanly suggesting how important prepping the surfaces is.

Test piece

Shear 26.6lbs OK

Failed

Pitot Testing 1

Date:  08-08-2016
Number of Hours:  3
Manual Reference:  no ref

I plan on a submerged pitot (anti-ice old glider style) that will sit just above my nose light. I have a nifty pressure tester that couples with an iphone app. The tester is the blue phone size rectangle in the pics and I used my ipad for the controls.

I really need to test as close to 180 knots as I can but maybe 40 or 50 will tell the story. I’m thinking can I angle the pitot without changing its pressure collection much at all?

Certainly a regular pitot would be an issue as such a small opening would soon have its lip covering the ‘relative wind’. What about a 1″ tube that collects the pressure before it gets to a submerged pitot getting the pressure off the back wall of the tube.

Interesting…. So I build a wind tunnel using my domestic fan in about an hour only to discover it makes around 6 knots of wind. Not enough!

Plan B is to stick my hand out of a moving car window for the test. Anybody need a used cardboard and pipe wind tunnel?

Wind tunnel

Tunnel exit

Testing pitot

ClickBond Test 1 Through a layup.

Date:  08-27-2015
Number of Hours:  2
Manual Reference:  no ref

I want to use Clickbonds in my build but I’ve never tested them myself. Will they turn when you torque up a nut? How strong are they? Are they going to be OK for primary controls?

Test 1 is going through a layup say instead of an AN screw for the rudders for example.
A separate test is needed for a bond to the outside of a surface.

For my test I used a clickbond that takes a standard AN3 nut.
I used a four ply layup of BID.
I after drilling a hole for the thread I routed a circle so the metal base wouldn’t stand proud of the outside. I probably lost most of one ply doing this.
I floxed the clickbond in place. I did not prepare the surface by cleaning it. I did not drill holes in the base to make fingers for the flox to grab. I wanted a worst case bond to test.
I covered the outside disk with the thinnest glass I have and peel plyed it.
The result was an almost smooth surface.

After cure, I used an AN3 lock nut and torqued to spec of 25 inch lbs (most references have AN3’s 20-25 inch pounds)
I kept upping the torque values. At 100 inch lbs the click bond distorted as you see in pic 3.
At 120 inch pounds the click bond failed by snapping at the base. I was using a wide area washer.
The glass did not fail and the click bond never rotated.

After this I have no hesitation in using these fasteners where applicable.

Dry fit

Cured in place

Test at 100 inch lbs

Spar Cap Tests 1

Date:  02-02-2014
Number of Hours:  10
Manual Reference:  no ref

The spar caps are a critical structural item on my plane build and I wanted to learn about how to do this work before attempting it on the real thing.

My goal was to build a section of the CS spar cap and find out how thick my special UNI tapes will layup per ply and to develop a good technique.

First step was to find a piece of scrap divinycell. Then I marked out a 3″ trough, actually 3.1″ to match my 80mm tapes. Just for the practice I put in a two ply UNI shearweb. I hard shelled it just to see how much extra time this added to the job and to try using power tools for sanding.

It adds quite a bit of time and while I think this method is good for some areas, in the end I used a wet micro layup for the real job later. I think the foam cells are so small here I’d go for the primary bond for the extra strength and skip all that sanding.

The open cell wing foam is another story.

Cutting a test cap trough

Laying up the test shear web

Peel ply the web

 

Spar Cap Tests 2

Date:  02-03-2014
Number of Hours:  6
Manual Reference:  no ref

Next step in my spar test is to layout the spar caps.

I first built a nifty UNI tape dispenser which will get a bit of use with CS spar, two wings and the canard to do.

It took 4 hours to layup only 20″ of this tape! The key thread of each piece needs to be teased out which then will release all the cross fibres which need careful pulling out. The tape then lies down beautifully.

It needs some attention to get the tapes in the correct direction so the threads are accessible for pulling out. I made a 3″ wide squeegee which was the heart of the technique for wetting out the cloth along with a heat gun.

My practice piece simulated the various thicknesses so that I could later workout how many plies I need to fill the CS spar troughs. This is important as we go from full length to shorter ones so it MUST have the right number to start with that go all the way.

UNI Tape dispenser

Cap weights

Results

Spar Cap Tests 3

Date:  02-04-2014
Number of Hours:  4
Manual Reference:  no ref

Once the piece was cured I removed the weights and peel ply and then cut all the foam off.
Here are some calcs and thicknesses close to what I will use for the top CS spar cap.

Ply   Depth Length BL
6      0.15    113
7      0.175  100
8      0.200   94
9      0.225   90
10    0.250   80
11    0.275   74
12    0.300   70
13    0.325   60
14    0.350   54
15    0.375   50
16    0.400   40
17    0.425   34
18    0.450   30
19    0.047   24

Test cap cured

Thicknesses marked out

Thin to thick

Peel Strength Tests 1

Date:  12-16-2013
Number of Hours:  10
Manual Reference:  no ref

This test was the second one seeking the best micro to epoxy mix when using the blue wing foam. I wanted to find out how much micro I could use in the mix, retain full maximum peel strength yet reduce weight. My second test was similar to the first but I was a lot more careful. I used 2 ply of the wing UNI glass.

All Blocks of foam were 8.2grams before layup 5” X 2.3”=11.5sq “ Blue Wing foam offcuts.
Peel force was measure by a cheap spring scale hooking under the foam and pulling consistently at an angle of about 150degrees down. Not deadly accurate but OK to give an indication. I tried to be as consistent as possible when pulling the cured glass from the foam.

I used the plans 1:1 by volume as my baseline in number1 sample. 1g of epoxy to 0.06 of micro is slightly wetter than plans but after testing is correct to use for divinycell foam. This blue wing foam is much weaker and has a very open cell structure so IMHO does not require so much epoxy in the mix and benefits greatly from having a thicker slurry. This fills the cells better and is easier to apply with less air being trapped on the surface.

You can see in the 3rd pic that all the samples came away cleanly from the foam proving its more a matter of weight and thickness, strength is not an issue. They were all sufficient. I’ll give a full report in the next entry.

10 samples

Force measurements

Samples peeled