Building a Nieuport 11...

[Frank Giger]

Today was a big work day, though there isn't much to show for it at the end.

First, Camlocks are in on the cowl:



A few little notes are in order. That's aluminum tape around the back edge to cover the rivet holes from when there was an extension and to help prevent scratching the cabanes and cheeks when putting it on. It'll be invisible after painting.

Then on to baffling!

I've worked out two thirds of the baffling, namely the left and right sides of it, using poster board. Time to put some of that cutting to the test with some sheet metal:



I freely stole from the KC Dawn Patrol page on the subject, modifying to suit.

There's a bolt hole on the far left (as you look at it) that will secure it at that point. It's intentionally wide so I can trim to fit the cowl to it for a good seal.

There will be a scoop of sorts that goes on the bottom of this down the cylinder like in the KCDP.

Here's a pic of the side:



I did this in two sections because it was just sooooo much easier that way. There are two bolt holes on the engine case a little in from where the nuts are showing to either side of the intakes.

Where I'm dipped is how to seal up behind the engine. Maybe a three sided box around the engine mounts? Or just run strips of aluminum tape on the offsets.

Also note that I worked until the sun went down on this, so the photography isn't the best.

[bookmaker]

Looking really nice, Frank.

Dale

[FloridaJohn]

Where I'm dipped is how to seal up behind the engine. Maybe a three sided box around the engine mounts? Or just run strips of aluminum tape on the offsets.

On my C-152, the back of the baffle goes vertical up to the cowl (parallel to the firewall). There are a couple holes to let the hoses pass through, and a flexible seal at the top touching the cowl. Seems like that might work in your installation, too.

[Frank Giger]

So I drove on with the baffling, finishing up the left side, and started to figure out the rear part of it.

After a couple of hours of screwing around with construction paper,* I came up with this:



It's a simple box that fits against the Diehl case and is inside all the hoses and wires.

Now it's just a matter of making into a two part metal box with a seam along the middle of the top - otherwise I'd never get it onto the engine.

* It took twice as long as it should have due to the lack of glitter-glue. Plus I did some other stuff, too.

[Frank Giger]

The box is taking shape in metal:

[Jim Hann]

Another bite of the elephant swallowed. Looking good Frank.

[Sam Buchanan]

Frank, how are you going to accommodate engine motion? Baffles usually have flexible seals so the engine can move without damaging the baffle or cowl.

Maybe I just can't see all the system in the photos.

[Frank Giger]

Sam, the baffles are more or less floating around the engine with some space.

Here's the finished box:



The box is actually held in three places to the aircraft: The firewall and at the bottom of the sides that go into the horizontal baffling. There is some play where the front and sides of the box are at the engine, which I'll put some aluminum tape over to seal it better (and protect the wires from rubbing).

The horizontal cowling is attached at the front and sides to the engine and the firewall, but it's aluminum and can flex pretty well. And it doesn't actually touch the engine at the cylinders (but is pretty close).

One of the things that surprised me is how little that engine moves, even at higher RPM's. I suppose it comes down to being a small engine with a balanced prop.

Cowl's not quite done, but it's shaping up nicely. Gonna need some sanding and an additional coat:



Oh, and I got the replacement tach from Valley Engineering and after figuring out the dip switch off/on diagram is reverse of what is on the gauge itself got it to work. I may never actually look at it in flight, but at least it'll be a working gauge I'm ignoring!

[Sam Buchanan]

The horizontal cowling is attached at the front and sides to the engine and the firewall, but it's aluminum and can flex pretty well. And it doesn't actually touch the engine at the cylinders (but is pretty close).

One of the things that surprised me is how little that engine moves, even at higher RPM's. I suppose it comes down to being a small engine with a balanced prop.

Frank, maybe I'm missing something but it appears to me per your description and photo that the baffle side is attached to both the engine and the firewall. That will crack. The engine may move only a small amount, but that will be enough to fatigue the aluminum. The baffle may be attached to either the engine or airframe, but not to both.

My apologies if I have misunderstood your baffle system.

[Frank Giger]

Hmmmm, lemme think about that.

Right now the horizontal baffle is bolted to the engine, and the box to the horizontal baffle.

I put in some sheet metal screws to the firewall at the back of the box and the horizontal baffle.

If I need to do one or the other, it's easy enough to remove the screws into the firewall - the box is solid without it, and the horizontal baffle is as well - I was just overbuilding.

I could put in another stiffening fin under the horizontal baffle (to keep with the whole idea of overbuilding) and then just put some tape along where it meets the firewall....it'll be cushioned against the cowl with some felt (as well as providing a seal). That would make it float with the engine, independent of the air frame.

Thanks, Sam, for educating me on baffling! This is precisely the reason I made this thread - so that smart folks like you can spot my errors and put me on the right path.