Back to Work - Cowling & a Big Move

Back home and time to get back to work.

I spent the better part of the morning digging out all the foam in the lower cowl mold. For some reason, the combination of drywall paste, car wax and mold release had a more tenacious grip, so the foam didn't go peacefully.

The first photo shows the cowl/mold just peeled off the engine.

















Finally, I decided to move my project back to my Tee hangar. It was really great to have use of the SIU Aviation Technology facilities, but it's time to move back home. They were kind enough to lend me a student worker for the afternoon, and we got it done in about three hours.

Once back, I took a couple of days to get the hangar properly organized. I learned a lot about organizing workplaces while I was at Dyno Nobel. Some of the main points I try to keep in mind:

• If you don't need it - get rid of it.
• Use visual clues like applying labels.
  
• Keep things you use often close at hand. Things you use only occasionally can be further away.

On vacation

We took a week off to take our granddaughters to Washington D.C. Take a look at Sandy's blog for the rest of the story.

Glassed the lower cowl

The next step is to make all that foam smooth enough to glass. One of the guys in my EAA chapter told me about using drywall compound. It's cheap, easy to get, and water soluble. I put on two coats, sanding in between.

After it's smooth enough for government work, I apply a coat of auto paste wax as a mold release. I also had access to a bit of water soluble mold release, so I gave a final coat of that, just for good measure.

I added two layers of BID then used sheets of dacron as peel ply.

We're going on vacation for a week, so you'll have to wait to see how it turns out.

Stretching the lower cowling

Now comes a part I have not been looking forward to - lengthening the lower cowl to match the upper.

The first thing I had to do was get all the basic engine components in place, the induction system, injectors, and the oil sump. I kind of pieced things together, but wasn't sure how to proceed. I consulted Jeff Sell and Q-2 cowl maker Earnest Martin and they pointed out the grim fact; I would have to flip the plane so I could get a better perspective on it.

Again, the hardest part is often deciding to get on with it.

Carbon Fiber Oil Sump

One of the main tasks is to build a CF oil sump. I wanted to cut down the amount of sump hanging in free air. (As usual, click on the photos for a large version).

I started a few months ago by getting out the Milwaukee Sawzall and start hacking on a chunk of foam. True to form, I just start hacking, then see what comes out of it.

After I got something like it might work, I tried to figure what to do about a mounting flange. I finally decided to make a sandwich with aluminum rings for bread and the CF for the peanut butter.

I kept whittling away on the thing, then finally coated it with drywall paste, car wax, then finally a mold release agent. This is a neat trick. The DW paste is water soluble. Before I coated it with the DW paste I did a water displacement test and it looks like it will hold five quarts. Perfect!

For epoxy, Mike Bergen helped me get some high temp ProSet. This stuff has a 300 minute pot life, but cures nicely in 24 hours. The only issue is that I have to post cure it to 250F or so.

The next trick was figuring how I was going to hole the flange in place while it cured. I figured I could make a little foam collar to support the flange. I would first wrap the entire thing in CF. At the neck, I would leave extra material which would form the flange.

I set the foam collar onto the sump, then placed the lower ring. I then folded the CF outward and placed the top aluminum of top of it. I guess the carbon reacts with aluminum so I first alodined it then I placed a piece of e-glass in between all places where the CF might touch the flanges.

I had predrilled a couple of tiny holes in the flange rings for alignment. I suck in a couple of cotter pins to hold the alignment.

After two days of cure time I spend an hour chipping out the foam. It was pretty easy and most of it came out without a fight. Since both the drywall paste and the mold release are water soluble, it left a nice clean, smooth inner surface.





A quick check looks like it's going to work!

Next comes the drain bung install and the filler neck and dipstick.

Can I make it to Oshkosh?

I have so-o-o-o-o much to get done - I don't know if I can pull it off.

The work is progressing steadily, but not all that fast. I just received the EC3 controller from RWS and have some SIU avionics students starting to help with the wiring harness, but I haven't really finalized the electrical drawings.

The big hitters on the to-do list are:

• Finish CF oil sump.
• Finish installing the new canopy.
• Finish the stretched cowling.
• Paint the cowling, wing and canopy.
• Complete the pressure fuel system installation.
• Install the new Dynon D180 and to all the ship's wiring.

Ugghhh. It's a big list.

Induction air

When I started this racing craziness, my wife and I were talking to Rob Martinson about how he gets his Vari-Eze to go so fast. He said that he goes to these races and pays attention to what the other guys are doing and borrows from them - and that's what I now do. It's kind of like going through the grocery store; I pick a little of this and a little of that.

At Oshkosh I sit in on any forums that have anything to do with speed, performance or efficiency.

As a result, this is where it starts getting really hairy - or should I say Harry?

At last year's Tandem Wing Spring Fling in Iowa City, I met a character, name of Harry Hinckley. Harry was modifying Greg Zimmerman's SX-300 for the upcoming AirVenture Cup race. One of the crazy things that Harry was up to was pulling his induction air from the cooling inlets. The idea here was to help reduce the drag of a separate inlet to feed the engine.

I thought it was probably kind of hair-brained and looked like a lot of work. As it turned out, Harry & Greg took second place in the Sport Class at a blistering 302.27 mph. See the rest of the results of the 2007 AirVenture Cup race. They were 11 mph faster than the closest SX-300!

So here is my attempt at having an internal induction air system. One of the hard parts was finding a suitable material to form the shape. After trying some hard plastic tubing that was difficult to shape, I stumbled across foam pipe insulation at the hardware store. I packed it with oil-dry to keep it from collapsing in the bends.

Once I had it duct-taped and safety wired in place I wrapped it with clear packing tape to make the interior as smooth as possible. I then gave it a single wrap of BID and spiral wrapped it with peel ply. In a couple of days, once the epoxy has firmly set, I'll slit the fiberglass, remove the foam, then glass over.

Initial concept using a shop vac hose.

Foam taped in place

Foam duck-taped, wired and covered with clear tape.

Glassed and peel plied.

Snouts

It's time to start on the cooling inlets. Click on the photo for a larger view.

Foam is clued to the plenum using two-part foam from Tap Plastics.

Shape until it looks like a snout.

I coat the raw foam with water soluble drywall paste. Then apply a couple of coats of automobile paste wax. This photo shows the left snout waxed.

Glassed with three BID

When cured, I chisel out the foam. The drywall paste dissolves in water and we get a fairly smooth interior.

Intake elbow and Throttle Body Installed.

Here is the installation of the TB and inlet elbow.

Induction & injector placement

It's finally time to start installing the Electronic Fuel Injection (EFI) system. The plan is to use a Real World Soultions electronic controller. For redundancy the RWS EC-3 controller has an "A" side and a "B" side. I will have five fuel injectors - one on each intake tube ("A" system) and a single one on the throttle body ("B" system). The engine will normally operate on the "A" system and "B" will be used if something bad happens and I need to get on the ground safely.

I am using an automotive racing throttle body from Jenvey, which has a provision to mount an injector on it.

I formed the intake manifold using blue foam, which I covered with water soluble drywall paste and then mold release. First I glassed the tube itself with 3 BID. I tried vacuum bagging it, which seemed okay. After cure I dug out all the foam and the inside was pretty smooth. The flanges were floxed in place and later I used 2 BID to secure the flange to the tube. After all that was done, I trimmed it and drilled the mounting holes.


I may not stay with this design, the sharp elbow may not be the most efficient, but it will be a good baseline for me.


















Click on the photos for a larger view.









The other big challenge is getting the fuel lines to all the injectors.

Stretching the Cowling

I thought it would be cool if I could lengthen the nose a little. I started by ordering a 7" prop extension from Saber Manufacturing. I also added the 60 tooth wheel that I'll need for the new electronic fuel injection system.















By the way, I was concerned about the trigger wheel rusting. One of the guys on the Q-200 Engine list mentioned Brownells Gun-Kote. I got a can off Ebay and followed the distructions. That is neat stuff and it worked great.














I really didn't want to take on making an entire new cowling, so I decided to just stretch the old one.


I sketched a few lines on the cowling of where I thought the cut should be.












It was kind of weird after I cut it up. It just seemed too easy to destroy it and the pieces that were left over seemed so pitiful.











I kind of jigged the two pieces in place where I thought they ought to go, then I used two-part foam to build a base for the glass repair. I got to dig out the Milwaukee Sawsall again, as I carved it out.


I put on two pieces on BID glass on the outside layup.




Once that cured, it was Sawsall time again as I removed the backing foam. Sanded the inside, then applied three layers of BID. It seems a little heavy, I probably would have been fine with two layers.

I'm pretty satisfied with it. The lower cowl will be trickier but I'm going to hold off on that until I get the new induction system, oil sump and fuel rail rigged up.