Building a Nieuport 11...

[planecrazzzy]

Well , there ya go...

We don't just build planes and fly...

We learn History while we're at it...

Thanks,
.
Gotta Fly...
.

[Frank Giger]

Early flight really interests me, as it's where the real engineering moxie of the guys back then came to the fore. We tend to think of them as simpler times, but in reality it was much more complex than today, owing to new technologies being leveraged against those that already existed. Airplanes were the ultimate in interdisciplinary arts - everything from cabinet making to metallurgy had to be known and used in both design and manufacture. Make it light, make it strong, and make it as inexpensively as possible - using only materials commonly available.

There was a lot of research on flight prior to the Wright Brother's figuring out how to truly control flight and Curtiss' development of the aileron, so the engineers of the day had a wealth of knowledge to work from, and as engines got better they could apply that to everything behind it. Rotating engines solved a lot of problems on the weight-to-power issue, but brought with it the gyroscopic problem; the solution was a free-flying rudder that, unlike the Wright Flyers, was unlinked from the bank controls (allowing the pilot to slip the aircraft). The early Nieuports sported both positive (lower wings) and negative (upper wings) dihedral to help it stay stable; they did this because they also made them short as they could to give them maneuverability.

They knew that biplanes were aerodynamically inefficient. But they also knew that using a box kite design gave the strength to the materials at hand far greater than the sum of the parts, so that's the format they used. From there they tweaked designs and materials as they went along, from streamlined wires to no wires at all (as in the Fokker DR1, which only got interplane struts at the insistence of the German war ministry). They worked with different airfoils, getting the best trade-offs between speed and lift.

But it's that interdisciplinary thinking that really appeals to me. They drew from every skill set in different industries and applied them to aircraft design and manufacturing, much as we homebuilders do.

[Frank Giger]

Getting back to the work at hand, as I mentioned I suck at putting down a nice smooth bead of silicone sealant/adhesive.



It occurred to me that while I've opted out of having an aluminum frame around the windscreen (as in the original), I can pay a bit of homage to that with a couple of little strips over that seam.

So I used my standard "take a piece of scrap and bend it until it looks okay" method of measurement and bent a bit of aluminum.

I didn't take pictures (I didn't know if it would work), but I found that bending a larger sheet to the correct angle and then trimming it thin on a paper cutter worked really well.

I also painted the strips using the same metallic paint as the metal joiney bits and then applied silicone stuff behind them.

To mount the windscreen to the aircraft, I made little mount brackets the same way I made the ones that hold the sides to the front, with a big rivet onto the fuselage and bolts through the wind screen. There's two in the front and two in the sides.



The scheme makes it a lot stronger than I thought it would. As the front is pushed back, the load is transferred along the sides, and there's a lot of surface area to take that stress. I grabbed the top of the center section and pulled back as hard as I could and it didn't budge.

Now, then, the upper edge of the windscreen which I had cut out with a jigsaw is great. It's smooth and flowing and there isn't a hitch on it, as I wasn't worried too much about it and just cut it with one motion.

The lower edge, where it meets the aircraft, however, is an entirely different matter. It's close and I've tweaked it on the band sander, but I didn't get the curve just right.

I could spend endless hours trimming here and there hoping for the perfect curve and the perfect beveled edge, but that's a pipe dream. Long experience tells me what I'd wind up doing it "improving" it right into the scrap bin.

What I need is something to cheat that edge, make it smooth, and keep air from travelling underneath it. I had good results using car door trim stuff on the seat for both appearance and smoothing, so I decided to go with that.

And immediately ran into a problem. The edge material is a square groove with a rounded tip of plastic/rubber material to make it rounded at the end, about 3/8" below the bottom of the square channel. Too much! And my windscreen is wider than the car door edge it was designed to go over, meaning I really had to abuse it to make it fit.

So I slapped in the remaining part of the steel I used to make the windshield mounts and put the belt sander to use.



I brought down the bottom to where I could just see the steel underneath.



Now it's about an eighth of an inch thick and flat on the bottom.



Test fitted it on the windscreen and mounted.



Since I wasn't sure this would work I cut it at the seam between pieces. I'll have to do it again, trimming down the sides at that join to make it one continuous seal, as well as hitting it with some steel wool to take the chrome appearance off of it.

[Frank Giger]

Here's how it looks all done:






I also found a new term: unforseen craftsmanship.

My wife was looking at the windscreen and said "one of your screws is off."

Now, I was about to go into the necessity of drilling some of the holes a little off center of the brackets in order to counter act the Coriolis effect and sunspots (always a ready explanation of my inability to center a hole on a piece of metal), when she continued,

"That one isn't going up and down."

Huh?

Well, out of 20 machine screws on the wind screen, 19 of them wound up with the screw driver slot vertical. The 20th was off by about 30 degrees.

"Um, well one of them has to be a little different from the rest in order to ensure the stresses on the installation don't loosen them all."

She almost bought it! Then she scoffs and says "you had no idea you did that!"

Nope.

[pittsdriver3]

Frank, There are over 300 philips screws in my L-21 Super Cub. All of the crosses line up as well as all the bolt heads. I think I'm mentally ill or have a bad case of ADD. Keep up the good work. The finish line is getting closer. Don

[Frank Giger]

That's actually pretty neat - but I'm not nearly that way. Heck, I'm happy when I can rivet in a straight line for more than four inches.

My FWF from Valley Engineering came with everything but the mounting bolts, so first order of business was finding out what size (3/8ths an inch) and how much I needed to back off from the Diehl case to clear it and the bolts from it.



I found an inch and a half or so back would do the trick. I'm not a big fan of extending the engine forward, as I have no idea what CG problems I'd be giving myself later on.

I'll wind up cutting the firewall and making a doghouse for the starter on the inside, which I have no problem with doing.

But I can't just have a grade 8 bolt out there all naked for that inch and a half, which means I'll need a bushing around it to beef it up.

The single bushing in 3/8ths an inch isn't beefy enough, so I'll nest three together:



There's a little lip inside each one to help it grab onto the next.



A couple whacks with a hammer (using a wood block to keep from damaging them), and we get a nice, solid bushing that's going to keep our bolt from bending.



Here's how it looks with the mount in place.



Now it's just a matter of doing that three more times, make a template for the bolt holes for the engine, and then mark the mount (after I clean it up) for center of the firewall, put the template on it, and drill.

[Frank Giger]

So I measured bolt hole to bolt hole and came up with 11" between them vertically.

But is that right? It would really stink to be off because I suck with a tape measure.

So I came up with the idea to drill a yard stick and see if the bolts lined up through them:



Sun's going down, so I'll wait until tomorrow to confirm horizontal distance. I don't trust to simply drill the center of the mount - best to be sure.

I'll most likely super glue some supports across and use it as a template for holes at any rate.

Oh, and note that on the stick to the left in the picture I had a problem adding eleven and came up with twelve...hence the "NO" to the "practice hole."

[Frank Giger]

Time to man up and drill some holes.

Or, rather, take a minute and measure closely on the mount and confirm some stuff.

First, I confirmed that the center of the Diehl kit is in fact the center of the crankshaft, which is the center of the prop. Simply a matter of putting a ruler on both ends of the engine.

Second, I leveled the mount while it is on the aircraft - meaning I leveled the aircraft. Easy enough.

Now, then, the center of my firewall was easy to find - I just ran a line from longeron to longeron; where they cross is the center, and more importantly the line of thrust.

I ran a level across the mount at the center:



Now it was just a matter of going up and down 5 1/2 inches from my center line, and running the level across again to make a line. Then I did the same for the horizontal distance.



Deep breath and on to the drill press.

From there it was back to the engine with the mount to confirm fit. Hurray!



A few notes - it wasn't entirely smooth sailing. Those rubber stopper thingies have a bushing inside them, and they like to be straight and center. There's a lot going on with those bolts - washers and bushings and stuff - so those vibration stoppers were fighting all the while.

I finally figured out that lining up and starting the lower two* first, then seating the upper ones and then tightening in an X (starting from the top right) everything started to sing.

* The lower two bolts were a PITA. The case to the engine does a little cut in and down, which doesn't give a lot of room. That's why there's a bushing on the back side of the mount. Turns out I measured correctly, and the bolts snug up just fine in the space allowed.

Hell, I'm starting to think it may be easier to put the engine on the aircraft as an assembly - with the mount attached - than it will be to undo the bolts, put the mount on the aircraft, then play the "line up the bolts in the holes" game I just went through.

[Geezer]

Frank, I'm very interested in Airdrome Aeroplanes and I stumbled across this thread.

Thanks a a million for posting all your adventures in construction.

The Hun will have much to fear!

Cheers

[Frank Giger]

Aw, shucks.

At any rate, this is an example of an Airdrome Airplane being built by the most ignorant of first time builders. When they say one can be built using normal hand tools (and a few non-exotic power ones like an electric belt sander, a small cheap drill press, a little air compressor for the rivet gun) in the space of a small car garage, they ain't kidding.

Most folks take the basic plans and modify them, making them look more like actual WWI aircraft or changing things up to suit their preference and turned them into award winners. I haven't done any of that - mine's about as "stock" to the plans as one can get.

My plane won't win any awards - but that was never my goal.

I only hope she can fly straight and well.