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Kent's Long-EZ project


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#141 Kent Ashton

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Posted 27 April 2017 - 08:14 AM

Pitch trim:  Here is a Cozy/EZ pitch trim system using spring wire.  (Cozy- 1/8" wires. EZ 3/32" wires).  The wires are adjusted by a welded-up nut on a threaded rod.  The rod is secured on a bracket on F-22.  In operation, the wires are always pulled forward to give down-elevator trim.  The wires are held in the nut by small retainers, not shown.  It is pretty easy to remove the canard with this setup: unscrew the wire retainers, lift the canard and trim wires out of the nut.

 

Gear down switches:  I put a homemade electric nose lift in the Cozy which did not incorporate switches for a "gear down" and "gear unsafe" warning.  No room to add them to the nose lift so here is what I came up with.  I like the comfort of having a positive "gear down" light.  It is something you can check quickly on final.

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-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#142 Andrew Anunson

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Posted 27 April 2017 - 09:24 AM

Pitch trim:  Here is a Cozy/EZ pitch trim system using spring wire.  (Cozy- 1/8" wires. EZ 3/32" wires).  The wires are adjusted by a welded-up nut on a threaded rod.  The rod is secured on a bracket on F-22.  In operation, the wires are always pulled forward to give down-elevator trim.  The wires are held in the nut by small retainers, not shown.  It is pretty easy to remove the canard with this setup: unscrew the wire retainers, lift the canard and trim wires out of the nut.

 

 

Very interesting!  A torsion bar trim spring....   Your spring wire is so long that is does not crack, break, or permanently deform (like the fiberglass trim springs do in some installations).

So... how do you like it?  

 

1.)  Are you able to get full elevator deflection (up and down) with the trim set at full up and down settings?

2.)  Do you have any photos of the actuating mechanism (which I assume is a handle or knob in the IP).

3.)  Any problems with your retainers out at the end of the springs?

4.)  Does this system affect the balance of your elevators?  You've added some weight to the system... does this make the elevators tail heavy?

 

Thanks for sharing your designs.


Edited by Andrew Anunson, 27 April 2017 - 09:25 AM.

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#143 Kent Ashton

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Posted 27 April 2017 - 11:24 AM

I like it pretty well.  I'll add a couple more photos later.  On the EZ i used a small electric motor to actuate the trim (See post #90 in this thread) but it's over-designed.  On the Cozy I have a 1.25"D knob to turn the threaded rod and barely use it once or twice a flight.  These airplanes do not need much trimming compared to say, a CE-172.
 
I can override the springs in any direction.  In the canards I've flown, the trim forces almost always pull the elevator down--or maybe neutral.  There is no case where you need to trim to hold the elevator up.
 
I haven't noticed any ill effects.  In the EZ, I used a different method for mounting the trim springs (See post #73).  It works just as well but acts more like the Davenport fiberglass spring.  That one is probably easier to make with a bit of welding.

Edited by Jon Matcho, 27 April 2017 - 04:48 PM.

-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#144 Marc Zeitlin

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Posted 27 April 2017 - 01:48 PM

There is no case where you need to trim to hold the elevator up...


You have obviously not flown an O-540 powered Berkut. They not only can run out of full up trim, but can run out of full up ELEVATOR and still be climbing, depending upon DA and power output :-).

#145 Kent Ashton

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Posted 06 May 2017 - 08:50 AM

Getting to work on my prop:  Found some nice maple at a local lumberyard.  Hard maple was desired; I am not sure I got the hard stuff, still, it seems pretty hard.   Glued with Weldwood Plastic glue which the Yahoo prop group seems to like.  Drilled the hub on the mill after trammeling the mill to get it squared up.

 

The bandsaw cut through the blank pretty easily with a 4-TPI blade.  The trickiest part so far is cutting away the excess on the diagonal without botching what will become the blade.  It is easy to get confused about where to cut--you can see where I marked it wrong once (5th pic).  I even glued back a piece I thought I had cut on the wrong side, studied it again and determined that I had cut off the correct side so I had to cut that piece off twice!  Duh.  Fortunately there was enough left to allow that.

 

Waiting for a burr to start with the router table.

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-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#146 Jon Matcho

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Posted 06 May 2017 - 11:35 AM

Impressive Kent! I know you've done the research, but I wonder why they favor "plastic glue" versus epoxy.

Luckily your brainfart was didn't cost anything. :-)

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#147 Kent Ashton

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Posted 10 May 2017 - 09:34 AM

Now you might think with one of those prop copier devices, you would go zip, zip, carve away everything that is not a prop and bingo--Your Very Own Prop.  However, I am not sure I will get a prop out of this exercise.  My blades are planned very thin.  I tried to cut them fat with the router to leave room for adjustment but not sure at this point whether I allowed enough.  I'm going to glass them so that'll help.  The question is: test fly it before glassing or just glass it and hope it works? Maybe I will glass the cambered side.  Or maybe the first attempt will be firewood.  It looks very rough at this stage.

 

If I get one good blade out of it, that might allow me to rout a new blank, taking a little more care.

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-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#148 Jon Matcho

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Posted 10 May 2017 - 10:10 AM

The question is: test fly it before glassing or just glass it and hope it works? Maybe I will glass the cambered side.  Or maybe the first attempt will be firewood.  It looks very rough at this stage.
 
If I get one good blade out of it, that might allow me to rout a new blank, taking a little more care.


I'm sure you're asking a prop-making forum, but I'll offer that wood to make another is far less expensive than other scenarios...

I am thoroughly impressed by all of this nonetheless!

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www.canardzone.com/members/JonMatcho (I know, it's broken... for now)


#149 Andrew Anunson

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Posted 11 May 2017 - 08:58 AM

Kent,

Well.... you've got your hands full... I'll give you that!  

I may someday enjoy overhauling my Lycoming by myself, but I really don't think I'll ever build my own prop.  If you get good at this, people may buy them from you... isn't this how Catto got started?

 

My Savier prop has birch laminates that are only about 1/6" thick... Klaus also used maple that was 1/4" thick.

What are the advantages / disadvantages of using thick or thin laminates?


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#150 Kent Ashton

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Posted 11 May 2017 - 11:35 AM

My Savier prop has birch laminates that are only about 1/6" thick... Klaus also used maple that was 1/4" thick.

What are the advantages / disadvantages of using thick or thin laminates?

 

 

Beats me.  I expect the thin laminates are dimensionally more stable.   I did not think about buying 1/4" birch plywood and laminating it until just now.  :-(    I bet that would make a good core.  My Performance Prop 3-blade was plenty stiff even without the glass.  However, from what I read, the core is not too critical for a glassed prop--could maybe even be balsa.   With a little sectioning in the CAD profile, I could use less wood with the birch plywood, too.  Anyway, it appears I'll be able to use this core.  It is getting pretty close on the back side.

Attached Thumbnails

  • IMG_0267.jpg

-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#151 TMann

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Posted 11 May 2017 - 08:59 PM

What are the advantages / disadvantages of using thick or thin laminates?

During construction of the blank, it makes it possible to change the direction of the grain of the wood which results in improved strength.


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#152 Kent Ashton

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Posted 12 May 2017 - 03:37 PM

Ya know, the folks who really have good experience building props do not let many of their secrets out.   As a rank amateur I'm happy to talk about it.

 

For example, the prop carver I made is perhaps a little taller than it needs to be so as the stylus follows the prop template, the router cuts in an arc.  Not a huge problem--the stylus can be adjusted to compensate but it's not the straight vertical cut one might imagine.  The cut is going to be an arc in any case but keeping the pivot point as close to the prop as possible would minimize it.

 

I got impatient and used an ordinary straight router bit but would've gotten nicer cuts with a coarse Saburr bit (pic).  The router bit wants to dig in.  I doubt the Saburr bit would do that.

 

As a first effort, I tried to cut the blades about 3/16" fat by setting the router bit higher than the stylus.  If I had more confidence in the thing, I would try 1/16" fat but my blades are thin and I didn't want to dig into them.  Of course, setting the router bit high does not help when cutting the side of something, like the leading edge.  That's what dry micro is for.  :-(

 

For removing wood after most of the sawing and chopping is done, I had a 3"diameter version of this carbide wheel in the angle grinder.  Worked pretty well but don't get sloppy 'cause it will really take off the wood.  Then a coarse sanding disk, then the hand rasp.

 

Lastly, the second iteration of blade-fitting templates.  Printed on the laser printer, glued to Formica sheet.  The 1" offset lines can be used to check the blade angle vertically and horizontally.  One prop-builder said to work the flat side to shape and to the proper angle, then gradually work down the cambered side until the templates almost touch.  Spray paint and go fly!  :-)

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Edited by Kent Ashton, 12 May 2017 - 03:38 PM.

-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#153 Jon Matcho

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Posted 16 May 2017 - 09:32 AM

Ya know, the folks who really have good experience building props do not let many of their secrets out.


Attached are pictures of a small cross-section of my damaged MT propeller starting 10" out from center. What strikes me is the dark and light woods (being two different materials) AND both are tapered in size in opposite directions.

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www.canardzone.com/members/JonMatcho (I know, it's broken... for now)


#154 Kent Ashton

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Posted 16 May 2017 - 09:46 AM

Interesting, Jon.  The dark part looks like fiberglass laminate but why/how does it get thinner?  Are you showing two ends of the same section?  And why do they embed dimes?  No wonder those props are expensive!  :-)

 

Here is some more noodling in my prop:  took a photo, imported it into CAD, scaled it a bit, drew some lines to get the hub transition consistent on both sides.

 

Attached Thumbnails

  • hub.jpg

-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#155 Jon Matcho

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Posted 16 May 2017 - 09:52 AM

The dark part looks like fiberglass laminate...


I suppose it could be, but the outside shows ~3 plies of glass which are thinner and of a different color. Conclusion: The dark area is fine plywood. There are around 12 plys near the root tapering to 3-5 outboard.
 

...but why/how does it get thinner?


I can figure the how, but not the why.
 

Are you showing two ends of the same section?


Yes, the same section ends shown in the first pic.
 

And why do they embed dimes?  No wonder those props are expensive!  :-)


To balance the prop. I assume you're kidding, I just wanted to show proportion.  :) 
 

Here is some more noodling in my prop:  took a photo, imported it into CAD, scaled it a bit, drew some lines to get the hub transition consistent on both sides.


Very nice!


Jon Matcho :busy:
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Rebuilding Quickie Tri-Q200 N479E
Building Cozy Mark VI+ (widened rear)
www.canardzone.com/members/JonMatcho (I know, it's broken... for now)


#156 Kent Ashton

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Posted 16 May 2017 - 10:06 AM

Speaking of LEDs, here is an idea for LED post lights.  I couldn't bring myself to spend $37 to $65 for a single post light.  They are a bit fiddly to make but they are "adjustable".  Stick them in holes in the instrument panel; twist and bend the soft aluminum to shine them where needed.  :-)   Dim them in sets with one of those cheap ebay PWM dimmers.

 

Not much need for them with a glass panel, of course, but they were fun to make.

 

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-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#157 Kent Ashton

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Posted 19 May 2017 - 07:54 AM

Prop progress:  Not perfect and will take a bit of spot filling before doing the glass but I think it will be OK.  It requires less than 50-cent piece on one tip to bring it in balance.  I think I can fix that with a little extra glass or some lead in the hub.  It turned out that the profiles cut by the prop carver and templates were pretty close even though I tried to cut them 3/16" fat.  If I do another one, I think I'd draw the template airfoils about 3/16 bigger and just cut a bigger airfoil, then work down to the desired size.  The leading edge was somewhat irregular; a little more care, practice and a different cutter would likely help that.

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-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs


#158 Kent Ashton

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Posted 22 May 2017 - 08:39 AM

Glassing my prop:  I have had luck before using a flox trailing edge about 5/16" wide.

 

I marked a 5/16" line, put a strip of peel ply down using alumium tape on the other side to keep the PP in place, then glassed.  (pics 1,2)  After the glass  hardens, cut and chisel the wood away (pic 3).  A better idea might be to cut most of the TE through but leave enough uncut that it will support the glass.  That'd be a lot less work removing the TE wood.

 

I also relieved the leading edge to allow for a BID overlap without making a bump but probably removed too much. (pics 4, 5).  The relief is larger on one side to fix an imbalance.  I'll use a little more glass in the overlap there.

 

So far, the balance is pretty good.  I thought I'd need a half oz at the 75% span but with the first glassing, it has needed less.  I think I can make that up with the final glass.

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-Kent
Cozy IV N13AM-650 hrs, Long-EZ-55 hrs





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