Nose and nose gear - part 2

Retraction system & NG-30s prep (8.3 hrs)

The original nose wheel retraction system consisted of a hand-crank mechanism that was light, and worked quite well. Notwithstanding these advantages, it created the need to turn a handle multiple times right after takeoff, and just before landing, something I have never been looking forward to.

Hand-crank to raise/lower the nose gear

One alternative I had set my sights on was one of the electrical retraction system manufactured by Jack Wilhelmson of EZ-Noselift, I chose the NL1-12E.

NL-12E system components plus NG15A and NG6A (aluminum pieces on left)

You can read all about it on Jack’s website, but I’d like to highlight the fact that it has a back-up battery pack able to power the gear down in case of a complete electrical failure, and the shock is contained within the actuator. Pretty cool!

This system is marketed as a retrofit for an existing short nose Long EZ with a manual retraction system, and the instructions reflect this fact, so they are not as useful as they could have been in my situation (new build), and I will have to modify the way I approach this installation.

So, with plans for a short nose I will not build spread out on one side, retrofit instruction for something that is not even here (and never will be) on the other, all the while keeping the long nose in mind, I started to untangle this mess.

Because of the “retrofit thing”, the installation will use the same bolt holes as on the original short nose with the manual retraction system, except for the lower one (let's call it A hole!).

On the short nose drawings, I first identified the 4 holes (the lower of which I will not use).

Original bolt hole locations

Then, I devised a coordinate system allowing me to locate the holes on the plans...

Locating the holes using a reference system

... and transfer them to NG-30.

Reproducing the hole pattern on NG-30

At this point, I tried putting all the pieces together as best as I could, to see how wide the whole thing would be, but I kept coming up with bigger dimensions that I expected. This was a problem, as the nose structure width must fit the center post of F-22.

Unsure if the problem was an actual one, or just the result of hastily holding numerous pieces up in the air while taking measurements, I decided to take the time to model all the nose structure components as precisely as I could, down to the thickness of the skin, in a CAD program.

Nose structure

Peeling the onion

This took a long time, but it eventually confirmed my suspicions... the nose structure came up 0.308” (8 mm) wider than the part it attaches to.

This looks like a problem

"It's always something, isn't it?"

"If it doesn't fit, you must acquit!"

While a little unsettling at first, I discussed my finding with other builders/fliers, one of which a mechanical engineer, and the general consensus is that making a flox corner between F-22 and NG-30 will restore, and actually exceed the original design strength of the joint.

Hand-drawn sketch of the proposed fix on my iPad

Although I was unable to draw it appropriately in the sketch above, foam will be removed from the core of the two parts, and the inner micro layer sanded off.

If I were to make F-22 again, I’d probably leave it 1/4” (13 mm) oversize at both ends of the center post, and plan on trimming it after NG30 installation.

In light of the recent fitting issues I uncovered on my nose, I decided to also model the actuator jack in CAD as faithfully as possible to ensure everything would fit all-right, and that there would be no more surprises.

Virtual actuator jack

Here’s the way the nose retraction system fits virtually...

Virtual fitting session

... and in reality.

Actual fitting session

Good thing I checked, because the virtual fitting session highlighted one more area of interference where the head of the actuator bumps into the top of NG-30.

"What now?!"

Interference volume highlighted in red

This was never an issue with the short nose NG-30s, since they were not as tall, but it is now, and my solution to this problem is to carve a small triangular niche in the foam 0.150” (3.8 mm) deep.

Modified NG-30 foam depth

Interference removal process

One other issue I identified through CAD, was that of the proper edge distance of the actuator bracket's holes when using my coordinate system.

Obviously something is slightly askew somewhere, perhaps my hole measurements wasn’t precise enough, or my hole pattern reproduction might have been somewhat inaccurate, or my modeling of the brackets... the point is, I made a mental note to not go by those C and D hole locations.

A week later, eager to get back to work, I forgot all about my previous assessment, and drilled those two holes per plans. 

"Measure once, drill twice. Doh!"

It’s really a smaller issue that it might seem at first, but it still pissed me off, and of course I figured it out just as I drilled the last hole.

Since the brackets already had the bottom hole predrilled with the correct edge clearance, I used them as a template to locate the correct position for the C and D holes on the brackets themselves. I will eventually use the bracket holes as templates to drill the correct holes in the NG-30s.

Ensuring proper edge clearance for the new holes

Using the drill press, I finalized their position once and for all by match drilling them.

Match drilling the bracket holes

The former misalignment is very apparent now.

Finding the correct spot

Moving on, I used the router to remove foam in the places where the hard-points will be created...

Free handing it

Nose gear hinge hard point (to be)

Done with the router

... and my “older than dirt” Dremel tool to make craters out of them.

Dremel action shot

Moonscape

Next time I'll fill the craters with "fiberglass disks", and cover the outside of both NG-30s.

Nose and nose gear - part 1

Pinocchio (9.0 hrs)

“Once upon a time, there was an airplane named Pinocchio...”. 

Ok, perhaps I should save that story for another time. 

Let’s just say that as naturally beautiful as it is, unlike the “real” Pinocchio, the Long EZ looks even better with a longer nose. Make that... much better.

A perfect example of "per plans" nose

Note how much further in front of the nose gear this nose extends

My first ride on an EZ was on Steve Volovsek’s plane, one of the fastest, and best looking ones out there, and it had a long nose. So, I am very partial to long noses, and I wanted copy his nose as much as possible.

For that to happen, the internal structure had to be substantially modified, so I plan to only partially follow this chapter’s instruction. Hopefully all the extra work will pay off.

One of the joys of building a disavowed airplane design, alone in your garage, is the intrinsic sense of mystique and adventure exuding from every part you make, and assemble. There is a feeling of discovery, and problem solving of the most basic kind, akin to a frontier man's journey into the unknown.

And so it is, that when an unsuspecting soul wonders into your shop - better yet, one that knows how to handle himself around epoxy and fiberglass - you don’t just let them leave without getting them dirty. Oh no!

Enter my good friend and Long EZ builder, Wade, publisher of the popular and informative EZ blog www.longEZpush.com. 

Catching-up time

Back from the “sandbox” for a couple of weeks, he decided to come and visit me for a few days. 

As per my master plan, Wade could not help himself from eventually wandering into the shop, and like a Venus fly-trap, the lid closed, glass and epoxy ready to consume him.

"Say Wade, wanna see my brand new fiberglass?"

Meanwhile, I had already set the bait... I mean, I had already cut and shaped all the internal components out of foam. 

Both NG30s getting "matched sanded"

Who could resist a spread like that?

The urge to build after a full year of just thinking about it (due to his work) must have been overwhelming.

Doesn't he look happier now?!

Wade found EZ-Poxy a little thicker than the MGS he's used to

As accomplished as he is, I could have easily left him alone in there, and waited for the completed airplane to emerge in just a few days, but I decided not to let him have all the fun, so I joined Wade, and slowed him down in any possible way.

I think Wade is starting to suspect my dark motivations, while I'm happy to have someone lighten my load.

I have to admit that it was a lot of fun working together, although I quickly became his “epoxy bitch”. That was a job that apparently befell his girlfriend, but she was more than happy to relinquish that title for a few days. 

Wade will probably go down in history as the first Long EZ builder to complete his own plane without ever mixing any epoxy. 

I'm just kidding Wade, you know I love you brother!

On a more serious note, apparently there might have been a few instances of nose structure cracking due to hard landings, and it seems like the general consensus is that a little extra strength in this area could have prevented it. Even though hard engineering data is not available (to me at least), a few people have taken the initiative to upgrade NG-30 to plywood in order to strengthen it, others have just added a few extra plies of glass instead. 

As my friend Ary recently did, I will also follow this second method as not to add any more weight, and add 2 plies to the outside of NG-30 and 2 to the inside. Ary has a very good description of the steps he took building the nose structure of his plane in his blog www.aryjglantz.com. 

I expect to do a lot of secondary bonding to these structures in the future, so I peel-plied everything in sight.

All peel-plied up and resting overnight

The last step of this building push was trimming and sanding the hard fiberglass, but Wade was nowhere to be found by then. Something about a “beer emergency” somewhere else made him leave before I could squeeze any real work out of him.

Usual post cure trimming session

Ensuring a flat back side to both NG-30s

That’s ok though Wade. Wherever you ended up, I understand and appreciate your sense of duty, and I would have probably done the same thing.

The finished parts turned out quite nice, and we both enjoyed doing some layups on flat foam, for a change.

Parts 50% finished. After glassing the other side I'll be able to start building.

Next time, these parts will be the subject of further modifications and topic of discussion, involving the electrical nose gear retraction system installation.

CNC mill conversion - part 13

The end of major construction on the Z axis, not!

Now that the main static structure of the Z axis has been machined, it is time to concentrate on fabricating (there goes that word again) those parts that will deliver the stepper motor impulses to the mill’s head, and make it go up and down. 

“On the menu for tonight are a couple of flanges, with a side of pulley modified to perfection, on a bed of flat bearings and races, topped with ball-screw and ball-nut. For dessert, may I suggest two very dissimilar adapters, and a funky looking bottom plate?”

Time to put the 2.5” (6.4 cm) 2024-T3 aluminum bar to good use.

Raw material

Aluminum slug

I first turned down the shoulder, this would have to slip inside the center hole of the 2.3” (5.8 cm) ball bearing I “pocketed” last time.

Turning down the shoulder

Then, I used a series of drill bits increasing in size to create a safe passage for the ball-screw.

Adding a pass-through hole for the ball-screw

What I ended up with is the blank for the top flange.

Looking more the part

The next two operations were done on the mill, using G-code I typed in by hand to locate the four X and Y coordinates.

Drilling holes for the pulley to come

Counter-boring the bolt holes to clear the 2.3" ball bearing

Using the same G-code on the mill once again, I substituted the pulley for the flange, and drilled and tapped 4 matching holes.

Customizing the pulley I bought online

Tapping the holes that will connect to the top flange

Putting flange and pulley together, I drilled and tapped 8 smaller holes that will attach to the still-to-be-machined bottom flange.

Pulley and top flange mated. Flange drilled and tapped to meet with the bottom flange.

Moving back to the lathe, I enlarged the center hole through the pulley to match the one previously opened in the flange.

More customization

Back on the mill again, I tapped the pulley to accept the ball-nut, and drilled/tapped two set-screw holes on the side.

"Tap-zilla" at work (15/16"-16)

Set-screw holes drilled and tapped

Time to concentrate on the bottom flange now.

Raw piece sawed off the aluminum bar

Facing the slug

Drilling the attachment holes to the top flange

While I had the flange on the mill, I decided to surface it down to the proper thickness using CNC, but I accidentally took a huge 0.300” cut instead of a 0.030", and "crashed" the mill.

Monster cut!

Well, that’s all part of the long and steep CNC learning curve. After modifying the code, I finished the surfacing operation.

Weird but smooth finish

In retrospect, I should have done this operation (and the next one as well) on the lathe, but I was itching to test the CNC abilities of the mill. It all worked out well in the end, but the surface finish could have turned out better.

One design change that I made, was to machine the flanges out of aluminum instead of steel. I did this for two reasons, 1) I already had the aluminum in hand, and 2): steel is more difficult to machine with my small machines.

Since I still needed to have steel surfaces in contact with the needle bearing for wear resistance, I bought two steel races to sandwich the bearing with. Unfortunately, I had already cut the top flange to the original length, and I did not want to start back at square one, so I machined a recess in the bottom flange for one of the steel races to fit in.

I did so by using a Wizard in the Controller software (Mach3), but I tested the code first on foam, then on wood, to "massage" the code before I cut the actual part.

Testing the code on soft foam

More testing on wood after code adjustments

Satisfied with the results, I gave it a go on the flange.

Recess machined on upside down bottom flange

Steel race fitted in recess

Next came another trip to the lathe, in order to reduce the diameter of the bottom flange.

Reducing the diameter of the bottom flange

That's weird, and cool!

Finally, the time came to test fit the assembly.

Parts count

Ready to close

All parts took their rightful place without issues.

The next problem I encountered, was a slight rubbing of the belt on the motor stand-offs.

I didn't see this one coming!

To correct for this situation, I turned the front two stand-offs down on the lathe.

Front stand-offs reworked on the lathe

No rubbing here!

All clear here!

My love/hate relation with the ball-screw was briefly put to the test again, having  to face/drill/tap one end of the hardened steel screw. Because this was to be the last time for this project, I suffered silently as the hard ball-screw tried to destroy my mini-lathe.

Drilling hardened steel is not for the weak.

But once through to the softer steel on the inside, all is well again.

Like a dentist fixing a cavity.

The plate that attaches to the head of the mill, and to the ball-screw, was nothing special.

Surfacing, boring...

Drilling and counter-boring, boring...

Counter-boring and drilling, boring...

Voilà, our transmission is ready.

All the components of the Z axis could finally be assembled for the first time.

Z axis modification completed, and ready to be mounted on the mill.

Bottom view of the lengthy mod

Unfortunately, as fine as this assembly appears to be, there was a serious problem afoot, more like a fatal flaw, waiting to threaten everything I had been working on until now.

Once I finally tested the assembly on the bench, I was horrified to see that, while the ball-screw did in-fact move up and down, it did so in a very wild, almost violent way. 

The ball-screw behaved like an alligator in the midst of a death-roll, and I was too shocked and embarrassed to record it on video.

Well, let’s leave it at that for today. 

Next time I will go trough the steps I took to understand, and correct this problem. It was definitely not a quick and easy fix, but I eventually worked the problem out of my Z axis. 

Stay tuned...