Is it just me or do most of you have problems getting that  cowl just right??  I have estimated that I have built about 57 full fuselage models since 1954.  Yesterday, I think I have finally made a cowl that fit almost perfectly the first go round. Usually I have to build two of them. The holes for the muffler bolts never line up, the hole for the needle valve seems to be off a tad and the hole for the head is always too far back.  Then I tend to hold it too tight and break part of it, until I get it fiber glassed or carbon fibered.

Wheel Pants....heavy sigh......the bain of my existence!  actually, come to think of it, its anything I have to carve a right and left of.

how do "they" do it different?

Cut lengths of wire or shapened dowl like skewers , & or shapen end of wire , and fitem into muffler & needle holes BEFORE tapeing the cowl exactly in place !

Then get in with the cranked nose needle nose plyers or a flat blade screwdriver behind the wire , And press it into the inside of the cowl.

LIKE a CENTER PUNCH Mark . !

Then press a new pin thru with pliers held square and true . Having it aligned and held square to the deck , or suchlike .

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If your cunning you just get a flashlight , Glare inside and use a new thin glasshead pin held square ( maybe with good small pliers = Or a PIN VICE , or in a small round craft knife
Or a Shapened 16 G ( 1/16 : dia. )  Wire in a modelling knife handle ) ive got a 1/16 drill bit in a round handle ( 5/16 od . ) Craft Knife .

A Pin you ' find the edges ' or on a good day , the center - off the hole . Central it will angle equally when wiggled . Cautiously . The Light Inside Helps .

Or Blind ' Walk ' the pin along a line estimated to intersect the Injun Case were Required .

A Sharpened pencil and ruler to mark the ' X ' .

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A Old Spare Engine Case ( AHEM . WE dont Use our GOOD Engine drilling & Sanding .  ) isnt a bad idea for such acupunctural work .

Another cunning trick is lengths of brass tube ( or Akumn. ) say from the K&S scrap packs , through for round acces holes , Epoxied in the cowl then filed flush .

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EARLIER meant to say = Brass tube sleeves to match wire dia. to muffler . NVA holes etc helps sometimes .
Here , Glueing Em , U Use the well screwed down case to align the dowls to align the sleeves while the Glue Goes Of .

Course the Holes need to be central , or at least not offset to the point theyre holding side pressure on the ' finishing tube ' your fitting .
Sanding & or solvent wash before getting the glue out , and you have the solvent at hand to continualy remove the dratted epoxy from your fingers BEFORE you put Paw Prints From A to B .*

( " im not sure if polite old ladies realise This MEANS arsehole to breakfast , Which is why A to Z is Preferable in more ways than one )

I haven't made that many, so I don't have much to offer.

When I made my first stunter cowl, I had this block of balsa all whittled and sanded to shape and decided nuts to this, I'll use this cowl to make a lady mold and vacuum bag carbon cloth in it.  I've made several cowls this way.  They still take a lot of fiddling.  My plan is to 3D print the next one.  It's not really modeling, but it's not for a Classic plane, so maybe it's OK.

Trivial Pursuit

I have found starting with a spacer attached to the engine by the prop nut a good way to go.  Make a front "washer" and fit to the bulkhead, then join the sections together and fill the holes with wood around the engine.  Take it off and shape the inside then filler...paint...

Oh weight... er wait, this gets weighty...  Good thing the planes I have done this needed nose weight anyways.

Phil

I agree with you Ty. Unless your a nat's
flyer your time is better spent flying. I
 spent too much time with routers and
dremels.

George





Cardinal

I really like the way the new stunters are done, with no cowl, just the opening to insert the motor/tank.  I'm contemplating doing that on a Nobler I am going to strip, repair and recover.

Hi Charles.  I guess that would depend if anyone wants to see yet another Nobler ARF being bashed! LOL  And of course, if I ever get around to it.  I'll probably get you to do some of those amazing graphics you do.

I like my cowls.

and all this time, I thought it was just me.
To make anything truly difficult....you must first put a cowling around it

Well, Ken, I built a bunch of speed models and 4 proto speed models. The cowls were all fabricated from bits of balsa, basswood and 1/64" plywood. Not that difficult. I'd NEVER start from a block of wood. That's why glue was invented, plus you can then get the grain going the right direction, to make it easier, vs. more difficult.  While assembling the cowl, get it to where it's bolted on, then drill through the engine for muffler bolt holes and NV hole. Plug the opposite side if you must. Then continue sanding it to shape. Safer than carving, for both parties involved.  Steve

Mount the engine.

Get a long piece of card stock and tape it to the fuselage someplace behind the back of the cowling. Mark the card stock and fuselage so you have register lines. You will need them when you put the card stock back.

With just the engine in place, press the card stock against the engine. You can trace the exhaust area and mark the needle valve hole.

Remove the card stock and place it someplace where you will remember where it is. I forget a lot.  

Attach the cowling. Have at it, sand, shape whatever.

At any time you can put the card stock template back in the exact same place. You made register marks, remember.

Lay the template against the cowling and low and behold, your tracings are exactly correct.

I did this on the Loser/Mig-3. I might have on the Stuka?

Good luck,

Charles

Hmmmm

If I understand the problem correctly you have no problem making cowls, just making the various cutouts to match your Motor.

The method I use is the following which works equally well for balsa or composite cowls in my experience.

1 after final shaping of the cowl (originally spot glued in place) on the fuselage, break it free from its spot bonds and set it to one side / hollow as needed.

2 temporarily bolt the engine in position.

3 obtain some heavy paper or light foldable card sheet and some masking tape.

4 starting with the cylinder head, cut a hole that matches the head size ( in olden times  this was a round shape) in a sheet of the heavy paper and slide the paper over the cylinder head to ensure it fits well.

5 now whilst the sheet of paper is still in place over the top of the head, tape the end of the sheet of paper to the fuselage.

6 slide the paper off the head, being careful not to unseal the paper from its tape held position on the fuselage and fold the sheet back so you can..

7 unbolt the engine (if required) and refit the cowl.

8 now... fold the paper back into the same position and mark the cylinder head hole on the cowl.

9 do this lengthy and arduous process for all remaining holes/cutouts

10 cut holes slightly undersize following the marks you have made.

11 gently file these openings until perfect (relative term)

Alternative - a more accurate (if slightly more expensive process);

Use a 3d scanner (75-$1500) and 3D printer ($500-$75,000), make a female rubber mold ($100 ish) and make multiple carbon glass versions with cutouts already in place.


"You're welcome"