Different cowl idea???

[1avidflyer 1983]

Hi all,  I've been thinking about my cowl, and after looking at some certified planes, I was wondering about using a fiberglass nose bowl, and then aluminum from there back to the boot cowl.  Top and bottom could be held on with screws or camlocks, and sides could hinge on the top piece.  It would make for real easy access, and probably be lighter then an all fiberglass cowl.  Anyone ever do this or have a good reason for shooting holes in this idea?  Thanks,  Jim Chuk

[Av8r3400 1179]

This is very similar to the way my friend Dave did his cowl.

He made an aluminum boot cowl under the windshield (a-la Piper Vagabond), only then he used the front half of an Avid mark IV cowl upper and lower.

There would be no reason you couldn't use a nose bowl and make the front section of the cowl as you stated.  The nose bowl will be big, though.  It will have to be cut down narrower and possibly shorter.

[1avidflyer 1983]

Someone on barnstormers had a PA-11  Wag aero nose bowl, but it's 33" wide.  That's ` 1" wider than the firewall on the Avid.  Don't think the  Continental engine is that wide that the bowl would be that wide.  Funny also, when you think that the PA-11 is tandem seating and the fuselage has to be narrower than the Avid or Kitfox.  Lots of time before I'm going to actually need that cowl, so lots of time to think about it.  Jim Chuk

[EDMO 1078]

I could measure next trip to airport - J3 nose is narrower because they let the cylinder heads stick out of the cowl.

How about one of those speedy types. like Pitts, where the cowl is narrow and has bulges on sides for heads?

Are you needing parts for a bump cowl?

EDMO

Edited 10 Nov 2015 by EDMO

[kosseman 3]

like this c model

[1avidflyer 1983]

This last picture of the C model is more like what I was thinking about, at least in the fiberglass/aluminum mix of making a cowl.   What plane is that nose bowl from?  Jim Chuk 

[wypaul 449]

The problem with buying a nose bowl is they are just not quite right for your application.  The ones available are mostly for air cooled engines and will be draggy.  When I switched to a Jabiru for my Q2 I bought the nose bowl from Jabiru and built the cowl around it.  When it was all said and done it would have been much easier to build the cowl from scratch.  My suggestion is to design and build the fiberglass nose bowl to suit your application , it is an easy and fun project.  Epoxy is easier than polyester resin to work with and finish. The cowl we built for my friends Piet had the side open at the fuselage for the same reason as the Supercub, tandem fuse and a wide air cooled engine.  That style of cowl sure makes it easy to open the cowl for inspection.  Paul

 

[TJay 1041]

Good to know WYPaul I am planning on adding  4 inches to the rear of my cowl that way my E box is all hidden under the cowl Not sure how to do glass work, Never really done it but good to hear tips like that. My cowl is from 1985 so im sure it is not epoxy, so does that mean I cannot use epoxy

[EDMO 1078]

TJay,

I was laying up fiberglass cloth and mixing epoxy resin/hardener back in the 1960s - I don't have any idea what your cowl Is made from, but I know that epoxy wont stick to Dacron polyester.   I am guessing the KF cowls were made of the same fiberglass and epoxy as the gas tanks.  Why not just make your 4" extension in the back like a boot cowl aka Avid and fasten your cowl to it?

EDMO

Edited 11 Nov 2015 by EDMO

[1avidflyer 1983]

I've had to do patching on my Avid cowls, and used the fiberglass resin that is sold in most hardware stores.   It stuck just fine.  It seems it will stick to just about anything except  plastic.   Built a complete cowl once with the same stuff as well.   I bought a bunch of fiberglass cloth and matt on the net years ago, and still have some of it left.   Jim Chuk

[EDMO 1078]

We used REN brand epoxy at Chrysler - think the number was 4310.   I used the West System with the measuring spouts on the cans for my boat consoles, and liked it better - Yes, I had a boat once, to dipnet my quota of salmon each summer in Alaska - Always wore my PFD...

All of the epoxies are $pendy, unless you can order in 55 gallon drums like the pros do.

I ordered the Avid Magnum boot cowls so I don't have to lay up epoxy and itch from cutting and grinding a lot of fiberglass - I hate that part!

EDMO

Edited 11 Nov 2015 by EDMO

[wypaul 449]

Good to know WYPaul I am planning on adding  4 inches to the rear of my cowl that way my E box is all hidden under the cowl Not sure how to do glass work, Never really done it but good to hear tips like that. My cowl is from 1985 so im sure it is not epoxy, so does that mean I cannot use epoxy

Epoxy will stick just fine to the polyester resin but like Ed said not Dacron fabric,  We use that as peel ply for smoothing out a layer and making a good surface for bonding more layers.  Polyester resin on the other doesn't stick to epoxy worth a darn and one other note, chopped strand mat only works properly with the polyester resin.

West is the brand of epoxy that I like, mostly for the easy mixing with the pumps.

[jackak 20]

Have you seen Byron Miller's cowl on the yahoo site?  He used aluminum and a fiberglass nose bowl. It's in the photo albums area under Byron Miller.

Jack

[1avidflyer 1983]

Wonder where he got the nose bowl.  That is kindof what I had in mind when I got thinking about the fiberglass/aluminum combination.  I'm always wanting to look at the engine, and having just two fasteners holding the side on, it would be real easy.  Jim Chuk

[ChrisBolkan 130]

This is a bit off this topic and I hope no one flames me, but I am not a fan of boot cowls on our simple little planes.

I find boot cowl setups to be a pain in the ass and weigh more than the simple two piece full length setup. I know boot cowls when properly implemented offer better fire protection than the two piece simple setup, but I prefer the simplicity of a two piece cowl setup.

My MKIV had the two piece setup and it was so easy to access everything (engine, firewall, through firewall penetrations and instrument panel) for inspections, changes and maintenance.

My Fat Avid had a boot cowl setup. The added complexity added a ton of weight and made looking and working behind the instrument panel very restricted. Impossible without removing the panel and all of the associated pain in the ass that is. 

I hated working on the Fat Avid so much I started over with a two piece design, and while not flying yet, I am SO happy I did it. it is so easy to work on and fit things. So much simpler from a practical standpoint.

Just my 2Cents.

Chris

[1avidflyer 1983]

When I did my last Avid/Jabiru cowl, I cut it at the fire wall and the back piece could stay in place while just removing the front top.  Back was held on with the same fastener locations as if it had been a two piece cowl, just had more camlocks holding the back of the front cowl to the firewall where it met the back cowling.   I did fiberglass the back top and bottom pieces together.  Jim Chuk

Edited 11 Nov 2015 by 1avidflyer

[ChrisBolkan 130]

If the back half is easily removable like the front portions like you describe, it seems like the best of both worlds.

I've never seen one put together like that. My Fat Avid was not. The boot portion was setup as a fixed part of the airplane not removable.

 

 

[1avidflyer 1983]

When I got this Avid/Jabiru cowl from the factory, it was two pieces, top and bottom.  I cut it off, and glassed those back parts together.  Used the existing fastening locations for that back part.   Three on each side, and one on the top if my memory is correct.  Jim Chuk

[EDMO 1078]

When I got this Avid/Jabiru cowl from the factory, it was two pieces, top and bottom.  I cut it off, and glassed those back parts together.  Used the existing fastening locations for that back part.   Three on each side, and one on the top if my memory is correct.  Jim Chuk

Jim,

Was your cowl long enough so you could overlap the front to the back part, or did you put a connector strip inside to attach them together?

EDMO

[1avidflyer 1983]

I'll have to take another look at it.  Memory is great.  (once in a while)  Jim Chuk

[TJay 1041]

When I did my last Avid/Jabiru cowl, I cut it at the fire wall and the back piece could stay in place while just removing the front top.  Back was held on with the same fastener locations as if it had been a two piece cowl, just had more camlocks holding the back of the front cowl to the firewall where it met the back cowling.   I did fiberglass the back top and bottom pieces together.  Jim Chuk

Jim this cowl looks very similar to my Kitfox 1 cowl, how does the jabiru fit under there, On mine it is very tight like cylinders and exhaust are slammed tight up against the sides and front. Just wondering if you did anything special there.

[1avidflyer 1983]

This was the cowl I bought from Avid about 8 years ago.  The guy in Montana will still make them, he has the molds.  I've got a new one for when I get to that point on my Avid rebuild.  I think he charged me what he got paid from Avid, cause the new one was almost half price of the original.  I did have to make the bump in the top of the cowl, that is where the starter on the engine goes, and there isn't enough room.  These cowls were copied from Jabiru's cowl for a Kitfox copy that was built in Australia as I understand it.  I'm still toying with the idea of using a fiberglass nose bowl, and then making the rest of the cowl out of aluminum.  That's how Champs and Chiefs are done, and it gives good access to both sides of the engine with just 2 fasteners per side for the access doors.  Probably a bit lighter as well.  I pulled a pic of a Chief off the web that shows the cowl to better explain what I mean.  Back to the Avid cowl.  It came as a top and bottom.  It was about 1 1/2" to long.  I cut the back off, fiberglassed it together to make a boot cowl, then cut the front halves to the right length.  It was a fair amount of work as well.  Here is the cowl builder's contact info.   Ron Smith    158 Andrea Dr.  Belgrade Mt.  59714     406-388-3099    ronallpro@yahoo.com    Hope I've been of some help :-)  Jim Chuk