Building an Engine Cowl

[Gerryy]

Keep an eye open for the July issue of Model Airplane News. I'll be showing how I build a "one-off" balsa and foam engine cowl for my Staudacher 300GS. The technique for using fiberglass and finishing resin is easy and can also be used to make a production plug for making a female mold so you can form fiberglass engine cowls.

Note: If you can't see the photos in this string, be sure to register and get a user-name and log in! Then you will see the pictures!
GY

[Gerryy]

I thought I'd give everyone a sneak peek of this article.
Here's the stuff you need!

[Gerryy]

Here's the engine attached to the engine mount box assembly

[Gerryy]

Start with your spinner and make a plywood spinner disc. Sand smooth and stick to spinner backplate with 3/32-inch double-sided sticky foam tape.

[Gerryy]

Make the face of the cowl, out of 2 layers of 1/4-inch or 1 layer of 1/2 inch balsa. Mark the air inlets but don't cut them out yet.

[Gerryy]

Tack glue the cowl backing pieces to the firewall. The top piece is cut flush with the outer edge of the fuselage. The two sides are inset slightly so the side pieces can be glued to them and still be flush with the side of the fuselage.

[Gerryy]

Tack glue the spinner disc to the face piece and then bolt the spinner backplate to the engine. make sure the face piece is level. Cut out and glue the two side pieces to connect the face piece to the cowl backing pieces at the firewall. The sides pieces are made of 1/8-inch balsa.

[Gerryy]

Add the corner doublers to the inside edges of the side pieces. here I used 1/4 inch sheet (bottom) and 1/4 inch square pieces (top.)

[Gerryy]

Plank the bottom of the engine cowl with 3/32 inch balsa sheet.

[Gerryy]

Now is a good time to make the needle-valve and glow plug driver holes in the side of the cowl. Before the foam top is added, you can see how things line up.

[Gerryy]

Cut a piece of 2-inch blue insulation foam to size and place ontop of the balsa sides. You'll have to carve and route the foam to fit around the engine and engine mount. Another piece of foam will be added to the fill in the rest of the space behind the balsa face piece.

[Gerryy]

Roughly cut and trim the foam blocks to the shape of the engine cowl sides. Once this is done, you can start to rough shape the entire foam section! But doen't glue the foam into place just yet!

So, have I got your interest? Tune in next week for more details on this build-along.!

Let me know what you think... there are about 20 more steps I will post.
GY

[Gerryy]

use a template to mark side-view shape of the cowl top

[Gerryy]

After cutting foam to side shape, start removing corner material to round the block

[Gerryy]

once roughly shaped, epoxy the foam block into place

[Gerryy]

Here the foam has been smoothed to shape. The blue tape protects the fuselage from the sanding bar

[Gerryy]

Spinner ring and spinner fairing block have been shaped and added

[Gerryy]

Balsa spinner fairing added to bottom of cowl

[Gerryy]

cowl removed from fuselage then fix dents and seams with filler.

[Gerryy]

after sanding filler smooth, apply fiberglass cloth with pacer Finishing Resin

[Gerryy]

After resin cures, cut and trim cloth to shape and sand edges smooth. Apply cloth to balsa sides and two layers over the foam top

[Gerryy]

Sand cloth smooth and apply second layer of finishing resin

[Gerryy]

Sand resin smooth and apply glazing putty to fill pinholes

[Gerryy]

Apply fiberglass cloth and resin to balsa sheet and make the chin air scoop

[Gerryy]

Cut open the cowl, glue the chin air scoop into place, fill seams, sand smooth and spray on primer

[Gerryy]

Sand primer coat, fill pinholes with glazing putty

[Gerryy]

Glazing putty sanded smooth

[Gerryy]

Apply white primer, sand smooth and apply glossy white paint

[Gerryy]

All dressed up for the 2006 WRAM show. Decals and trim paint all sealed with a glossy clear coat. Watch for the complete "How To" article in the July 2006 issue of MAN! Give us your comments!
GY

[MasterAlex]

Gerry,

This looks fantastic. Thanks for pointing me to this thread. I loved the build article in the latest edition of MAN. Sold me on putting one of these togehter. Can't wait to get this started!

-MasterAlex

[Gerryy]

There are other paint schemes also for the Staudacher S-300 series of aircraft. The GS version is for Goulian pilot recognition. There is also a D-300 version and a few others, the web is full of them.
check out this website: http://acrodesigns.com/gallery/showgallery.php?cat=23&thumb=1

The photo here is another scheme I like. I also think that if you got a .60-size Extra 300 canopy, moved the turtle-deck bulkhead back about 2 inches and extended the cockpit forward a bit, you could do a reasonable S-600 2-place version. Orange and black in colors! See the Lanier RC site for their giant scale version.
GY

[MasterAlex]

Good Stuff!

Personally, I am partial to the S-300 version. Been looking for some good pics. Heck, it was almost like you knew I was looking!

-MA

[tandemairbike]

Totally cool operation.
Sure beats trying to get the holes in the right place with a ready built fiberglass or Vac molded cowl.
Many thanks for this one.

Tandy

[JoeMacD]

Gerry i just love the building article in MAN on the S-300. I might try building one my self.Does it fly like the CG Extra 300 or better? Is it 3-D capable?

[Gerryy]

Hey JomacD, I think the Staudacher is one of the best models I've built in a long while, being so closely involved in its design and development, I have to plead being a little bias but in general It is a really nice performing aerobat. I would compare it to the Goldberg Extra 300 in most repects but I think it knife-edges better and seems to land a bit easier. This I think is because it is a little lighter. There are a few different paint schemes for it so you can go wild with the covering. There was only one red, white and black one, being flown by Mike Goulian. He flew it for years before trading it in for the Cap 232.

Good luck and keep us in the loop if you build one.
GY

[JoeMacD]

Yes I will let you know when I do start to build one. I am very intrigued with the S-300. I had built 6 CG extra's
for my self and others.They all flew super good.but I think I will power it with the OS 1.08 I had in the Extra!Or do you think its too much engine!

[Gerryy]

Too much power for a Staudaucher? should not be a problem. Just make sure you have enough space in the front of the engine cowl. It does narrow down a bit. You might want to add a prop extension or something to bring the engine further aft. The box mount can be adjusted for proper engine spacing. I think a 120 4-stroke would be the upper end, so the 1.08 2-stroke should be OK
GY