Repairs & Mods: custom cowl, new gear,etc

[Willja67 144]

I should probably name this cowl humpty lumpty. So far my idea for building a cowl like this is working but if I were to do it again I'd use blue foam on the top of the cowl forward of the firewall and between the cheeks/ nostrils like I did on the bottom. There's just a little too much curvature there for the white foam unless it's supported better.  I think so far that the white foam on the sides has worked out pretty well.

 

Now I'm past the mudding and sanding phase and into the applying mold release aka duct tape and packing tape.  I'm cheap and hoping the packing tape works ok since it doesn't stick as well to the drywall compound but it's cheaper than the duct tape.  I'm using the duct tape for the compound curves and any place i think i need the tape to stick a little better.  I also added the longitudinal strip to mark the parting line of the cowl. Hopefully it'll be visible under the fiberglass. 

[1avidflyer 1983]

Looks like it's coming along.  I do wonder though if painting it and then some wax on the paint would have been better than the packing tape??  It seems that I always get wrinkles in the tape, and also where the tapes over lap there will be a bit of a ridge.  More sanding on the plug when you peal it off perhaps???  I'm not trying to pick your project apart, I'm more or less throwing it out there for suggestions of why it's a better or worse idea.  I may ending up making a plug myself for three or four different planes and want to nail down what will work best for me.  You're getting closer though!   JImChuk

[Willja67 144]

 

Here's where some of the idea came from. I also have the plans for the Thatcher CX4 and i'll have to look at them again but i think that was where i first learned of wrapping the plug in packing tape. Mike Patey is one of those guys that is so good and so experienced he makes stuff look ridiculously easy (and a lot of the work is not shown) but if you watch the video you'll see he had to do quite a bit of sanding and filling on his cowling. So you're probably right, but this is the way I'm going for now.

Edited 2 Nov 2018 by Willja67

[1avidflyer 1983]

Thanks for putting that video up.  I guess I had it in my mind that you were going to make a mold off what you are doing now, and then make the cowling out of the mold.  Just going over the top of what you have here and then sanding the outside of the fiberglass smooth makes more sense if you are just making one cowling.  Then wrinkles in the tape would be less of an issue.  I may end up making three or four cowls, and so I was thinking of it from a different perspective.  Keep at it, you are doing good!  And just to be clear, I wasn't being critical of the way you were doing it.   JImChuk

[Willja67 144]

Thanks for putting that video up.  I guess I had it in my mind that you were going to make a mold off what you are doing now, and then make the cowling...

 And just to be clear, I wasn't being critical of the way you were doing it.   JImChuk

No problem easy to misunderstand.  Don't worry I'm not thin skinned about stuff like this and didn't take it as criticism in any case.

[Willja67 144]

Just saw this video last night and it got the wheels turning.  We all know the KF1 has neutral yaw stability due to the small vertical tail.  At 6:52 in the video you can see some blue plates he had mounted on the h-stab. I know that float planes often have those added to give more stability due to the destabilizing influence of the floats. Seems to me like it would be a easy way to add some stability without major modification and acting as an endplate might even add some elevator authority. 

 

So good idea or had?

[Yamma-Fox 403]

Good idea.  And I probabaly need to do something with my KF5 going on floats, so I'll be looking for ideas.

I like this "watching you do my experimenting for me"!  LOL!

-popcorn and beer emoji-

[Willja67 144]

Good idea.  And I probabaly need to do something with my KF5 going on floats, so I'll be looking for ideas.

I like this "watching you do my experimenting for me"!  LOL!

-popcorn and beer emoji-

So far I don't think I've had any truly original ideas, but if it helps someone else seeing my missteps I'm happy to help.

 

I will be jealous of your 140 ponies though. Its not in the budget for awhile but if I could put a Bmw R100 in and have 15 more 4 stroke horsies pulling my chariot I would jump on the chance. Obviously I'd love 140 but the airframe won't handle it.

Edited 4 Nov 2018 by Willja67

[Willja67 144]

All taped off and ready for serious prep for fiberglass!

[Yamma-Fox 403]

I think this is gonna turn out great.   

How are you gonna do the camlock seam between the two halves?  Add in an "underlap" strip after you cut them apart?

[Willja67 144]

I think this is gonna turn out great.   

How are you gonna do the camlock seam between the two halves?  Add in an "underlap" strip after you cut them apart?

That's the plan exactly.

[Willja67 144]

Working on the layout for the fiberglass. Right now the plan is 4 plies of Rutan 8 oz BID 38" wide fiberglass over the whole cowl. All plies with be oriented + & - 45 deg from the longitudinal axis of the aircraft. The black lines in the pic are the 45 deg marks.  I think ive got the basic layout firmed up just needed to figure out all the little pieces. The goal is to have it layed up on Saturday.  It's only going to getup to 50 deg so itll take awhile to cure but working alone that's a good thing.  Also hope it'll keep 4 plies plus the overlaps from exotherming on me. 

[1avidflyer 1983]

I think it will come out just fine for you, and will be way easier to see over than the round Kitfox cowl.  Keep going!  JImChuk

[wypaul 448]

What type of resin are you planning to use?  I would suggest Epoxy because it is mush easier to sand.  Polyester resin is a bitch to sand, plugs up the sand paper.  With Epoxy you use micro balloons mixed with the resin to fair it up which there will be a bunch of that to do.  I like the West system Epoxy because the pumps make it easy to get the ratios right. Anyway just my thoughts.  

I have built a 24' sailboat with polyester a Q-2 with Epoxy and two cowls with Epoxy and would not go back to polyester for anything.  Vinyl ester may be an option that I would consider and then use Epoxy with micro to fair it up.

what ever you decide to use a small tent with a secretary heater under it over night will make the cure a snap.

The Rutan glass is great stuff to work with, wish I was there to help, it is very satisfying to build a cowling.

[Willja67 144]

What type of resin are you planning to use?  I would suggest Epoxy because it is mush easier to sand.  Polyester resin is a bitch to sand, plugs up the sand paper.  With Epoxy you use micro balloons mixed with the resin to fair it up which there will be a bunch of that to do.  I like the West system Epoxy because the pumps make it easy to get the ratios right. Anyway just my thoughts.  

I have built a 24' sailboat with polyester a Q-2 with Epoxy and two cowls with Epoxy and would not go back to polyester for anything.  Vinyl ester may be an option that I would consider and then use Epoxy with micro to fair it up.

what ever you decide to use a small tent with a secretary heater under it over night will make the cure a snap.

The Rutan glass is great stuff to work with, wish I was there to help, it is very satisfying to build a cowling.

I've got some aeropoxy I'm planning on using. I had thought of a tent and small heater. But maybe i'll consider that more seriously. Especially if my gear gets here soon and i can take the plane to get the gear brackets welded on the will be renewed emphasis on getting the cowling cured and off the plane. I don't want to accidentally damage it on a 120 mile round trip.  

[Willja67 144]

It's commencing! Here's the first piece of fiberglass cut for the cowling. 3 more similarly sized large pieces, 4 medium sized pieces, and a few small ones. Advice given to me by a cozy builder in my chapter was never touch it without gloves as the oil in your hands will keep the epoxy from adhering.  I'm also going to weigh each piece of fabric and mix only that much epoxy by weight for it and wet it out on a piece of plastic then drape another piece of plastic over that and squeegee the epoxy out to the edges that way the fabric holds its shape enroute to the cowling then peel the back piece of plastic off and drape it in place.   I'll link to s video soon showing the technique if that was hard to understand. 

Doing wet layups about the best fiber to resin ratio you can get is 50/50 by weight hence the measuring of the epoxy and fabric. Ive got all kinds of dreams for this plane. Eventually i want to build a carbon fiber vacuum infused cowl for it. If it's anything like the weight saving trent palmer got doing his that's 5lbs more useful load and less nose heavy as well. 

 

Trent Palmer Cub killer video

Edited 9 Nov 2018 by Willja67

[Willja67 144]

Well gentlemen those are the first 2 out of 4 plies. It only took me 6.5 hrs from when i started getting the epoxy out till calling it a night. As cold as my garage is i doubt it'll cure anytime soon. The plan is to finish the last 2 plies by Monday evening, then tent it.

[Willja67 144]

That aeropoxy is good stuff. Despite being in a cold garage for the last 48 hours it's already cured. That particular batch of aerpoxy has been through alot. I bought it over 5 years ago and it got frozen on the drive when i moved to Alaska and frozen when i moved back both times in the winter. It's sat in a tin shed in the summer and it still works just fine.  I'm going to have to sand the fiberglass before i can add the next plies and there's a bunch of bubbles that I'd be better off dealing with before the next plies go on. 

[Willja67 144]

My Christmas present to myself is here! Built by Stace Schrader of Rocky Mountain Wings LLC.  Looks pretty nice in white powder coat ( the plane won't always be silver). Now i really have to get that cowl done and trailer modified so i can make arrangements to get the welding done!

It comes with brackets to weld on for both the front and rear attach points but I'm hoping to only need the front ones that the cabane bolts to so i'll only have to have to grind off the front ones. Looks like the aft mount fits the original brackets just fine. Stace says it will be about a foot wider on each side and taller. 

 

[Willja67 144]

Just waiting for the glue on all these discs to dry and i'll put in in the lathe and see what happens.

It's 9.5" at the base and 8.25" tall made of 11 discs of 3/4" mdf.

This ought to be interesting, as I've never tried anything like this before. 

Edited 22 Nov 2018 by Willja67

[1avidflyer 1983]

Are you going to try to spin an aluminum one?  Or use it for a mold for a fiberglass one?  I have a never used Avid fiberglass one I might sell.  JImChuk

[Willja67 144]

Are you going to try to spin an aluminum one?  Or use it for a mold for a fiberglass one?  I have a never used Avid fiberglass one I might sell.  JImChuk

The plan is to use it as a mold for fiberglass.  I'm discovering my lathe is missing some parts so this might be a dead end. I'm not committing yet but how much are you asking for that spinner? I'm going up to Idaho to have Thanksgiving with my parents and my dad has a shop Smith lathe that I'll see if I can use while I'm there, so hopefully I'll be able to still do this the way I planned.

[Willja67 144]

The eventual success of this effort is more in doubt than the cowling. I turned the stack of discs down and because i had hand stacked then when i glued them ie didn't use the centering holes to line them up exactly one side of the spinner is concave so i slathered the whole thing in wood filler and when it dries we'll see if it can be worked with.

[Cloud Dancer 69]

I'm not sure what's missing on your wood lathe? Not much to them. Some people take the head and tail stock off old wood lathes like yours and make riser blocks to raise the head and tail stock higher above the bed. It will give you enough clearance to use them as spinning lathes. Most patterns are made of hardwood but if your only making a few, I would think the particle board pattern would be just fine. I've got some old cd's purchased years ago on metal spinning but I bet there's plenty of You Tube videos on the subject today.

I've got a CNC lathe to turn the plugs with so I might try to do something like that down the road. Most patterns for turning are made in a couple of sections so you can get the plug out but a nose cone plug looks like it should pop out easy enough.

Those Shop Smith's are nice tools for small shops. They can be found cheap on Craigslist quite often, especially the older models. Many times I have been tempted to buy one when I see them on Craigslist and at estate sales.

[Willja67 144]

I'm not sure what's missing on your wood lathe? Not much to them. Some people take the head and tail stock off old wood lathes like yours and make riser blocks to raise the head and tail stock higher above the bed. It will give you enough clearance to use them as spinning lathes. Most patterns are made of hardwood but if your only making a few, I would think the particle board pattern would be just fine. I've got some old cd's purchased years ago on metal spinning but I bet there's plenty of You Tube videos on the subject today.

I've got a CNC lathe to turn the plugs with so I might try to do something like that down the road. Most patterns for turning are made in a couple of sections so you can get the plug out but a nose cone plug looks like it should pop out easy enough.

Those Shop Smith's are nice tools for small shops. They can be found cheap on Craigslist quite often, especially the older models. Many times I have been tempted to buy one when I see them on Craigslist and at estate sales.

Some of the adjustment locking parts are missing. Plus I'm ignorant enough of what should be there that i just don't know what i don't know. 

The Shop Smith is a nice tool, too bad the company has gone downhill. My dad says that it often takes 6 months for parts to come, if they come at all. 

Fortunately I was able to get the spinner to the point where i can finish it by hand.