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Building a Javron Cub

ELT

I elected to get the Kannad ELT. This is a 406/121.5 unit with an internal GPS. It is the lightest ELT I could find and as best as I can tell about 1.5 pounds lighter than the other fixed ELT units. It weighs 1.87 pounds with the batteries. That does not include the mount or antenna. Yes, I did drill into a fuselage tube. I know some folks do not like to do this but I feel it is stronger than adell clamps and I did not drill into a longeron or other critical structure. So I am comfortable. Perhaps if you will be building a Javron cub you could have Jay weld on some tabs for this.

Here are some pictures.

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Hope this helps

Bill
 
Dave, The epoxy with flox is a lot stronger than straight epoxy and it was just the way Lancair had you do it. Also run a flat blade screwdriver around all the edges about 1/8-1/4" in and fill with epoxy/micro to seal them. West Systems is the best epoxy to use. Don
 
Don, I mentioned "thickened" epoxy...you could use whatever thickener you like. A 'cake decorator' bag (folded paper cone filled with "goo") works great to distribute the mixture.....a "ziplock" filled with the mixture and the corner cut off works, too.

The "bushing" is captured by more skin area, seemingly, with the bent nail trick. I see this as advantageous. ...just thought I'd mention that.

Also, have been up to my elbows in WEST, MAS, System Three (Silver Tip, General Purpose, and also the new Five-One, plus QuickFair) Devcon, Dubro, etc, etc, etc,

Is there a reason why you prefer WEST? Thanks for your answers.

Bill Rusk....Not that you should worry, but we have had problems with Kanad's Antennas...seems we are not the only operators.....also, seems like it is only on the turbines, not on the recips. The antennas are breaking internally, and you cannot tell by looking at it......you can tell by pulling up on the wire and the top wire pulls out ...FYI. Looks like we'll be replacing them with "blade" antennas.

DAVE.
 
Dave and Don

Thanks for the tips gents. Don - where do you get Flox?

I like the bent nail trick. That seems like it might be a player.

Dave - Kannad has three different antennas, based on speed. The whip for us slow guys, a mid speed unit for turbo props, and then the blade for jets. I will look into that. I had not read or heard of any problems from the antenna they recommend for recips. Perhaps it is limited to the mid speed band range unit. Hope so.

Thanks for the help, I learn from you guys every day.

Bill
 
Dave, I like the West as it is pretty idiot proof (this is important when a guy like me is working with anything) with their pump dispensers on the cans. It sands really well and will stick to about anything. I also developed a severe allergy to the Jeffco I was using on the Lancair and West doesn't affect me as much. Thinking about it I think your bent nail trick would work really slick. Sure be a lot faster than my way.
Bill, Spruce calls it Flocked Cotton Fiber pn 01-14780. You will also need some Micro. Spruce calls it glass bubbles pn 01-14600. Be aware the flox mixture is a bear to sand so only use it for re enforcements. The micro really sands nice so use it on edges and filets. I also laid up my windshield fairing in glass and it is stronger and lighter than the metal and fits perfect. It is pretty easy to do and another little detail that guys that know Cubs think is really cool. Don
 
I use Plaschem Supply and Consulting to source nearly all the composite materials. (907) 274-5505

Don, I love the idea of composite windshield retainer.

I've done composite wing root fairings and the fit is as good as can be gotten......slap a bunch of masking tape across the wing root to fuselage and windshield gaps, wax it a couple of times and then lay 2 layers of 6 ounce carbon bidirectional over the waxed masking tape....VOILA! and lightweight, also!

Bill, the part number for the failing antenna's is....I'll find it later and post it. D
 
Here is the windshield fairing. Only took a couple hours total to do. I messed with the stock metal fairing for hours trying to get it to lay down perfect with no dents or puckers. I've never seen a metal one on a Cub that looked good.
 

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pittsdriver

That's a great looking fairing! Did you lay it up in place over the boot cowl and windscreen or did you use an aluminum fairing as a mold?

Sam
 
Sam, I laid it up in place. Four layers of 6oz cloth with a peel ply layer. Put a thin skiff of micro on it, trimmed the edges and sanded it.Only took a couple of hours and it fits perfect with no lumps or bumps. Don
 
Engine arrived from Aero Sport Power. On schedule and on price. I am very pleased. I highly recommend Bart and Sue. Thank you guys. Great job.

Perhaps tomorrow, after a trip to the dentist, I will have a report on flywheels.

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We did not waste any time with a trial fit. Mark Rusche and Buck (shown here) were on hand to help.

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More to follow.

Bill
 
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Thanks for the nice comments folks. Docstory - geez I sure hope not.

FLYWHEELS

Went down to the engine shop and weighed a bunch of 149 tooth flywheels. They pretty much all weighed the same.

Average normal 149 tooth flywheel = 106.920oz/6.682pds
Mine after cutting off the pulley = 86.915oz/5.432pds
Skydynamics flywheel = 47oz/2.937pds as reported on their website (http://www.skydynamics.com/frame.htm)


So cutting the pulley saves just 1p 4oz. Really not all that much. But going from a full normal flywheel to the flyweight one from Sky Dynamics will save 3.75 pounds. Thats pretty significant, especially since that weight is way out front.

This is my flywheel before trimming the pulley off

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This is my flywheel after trimming the pulley off. My good friend Tom popped it on his lathe and had it done in a flash. Some like DW and Doug K have also drilled out theirs

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This is a picture of the Sky Dynamics magnesium Featherweight flywheel.

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Hope this helps. You will have to decide what works for you.

Bill
 
if he wanted speed, (like to go to the tee shirt contest you will be participating in next sun n fun Amy) he would be building a -12...
 
Yea, its pretty red. As in.... RED HOT baby. As in.... Sexy. As in..... climbing like it is on fire. After I opened the crate, and regained my vision, I decided to name this Cub..... ....wait for it........................Rudolph!

Floor Boards

I have tried to post both the good, and also my mistakes (even though it is embarassing at times) so others might benefit. I wanted to cut my own floor boards so that I could tighten up some of the holes and make it a little cleaner. It has worked a little but it is probably not worth the effort. Like that last 10% that takes 90% more work. If I were to do it over I would just order a set of floorboards precut from Jay. You can still do the composite material, (or plywood) but he has a fancy CAD machine that cuts them right out. Too much time and effort for little measureable gain on this one. Just my opinion of course. There is plenty of work on building a plane without beating your head against the wall for nothing. In that same regard, I am sure glad I let Bart build the engine for me this time. I built my last one, and again, lots of work. There will be plenty to do.....Keep it Simple. I knew this, I just wish I could take my own advice. I will post more this evening if I have time.

Bill
 
Know what you are saying. I went to the lumber yard and bought a sheet of 1/4" ply and spent 2 days making proto floor boards. Then I needed a little more for the final ones. Now to cut up the good stuff and hope I don't mess up.
 
I wanted to cut my own floor boards so that I could tighten up some of the holes and make it a little cleaner.

I "tightened up" some, and opened up the rear seat bolt holes, and then glued on some scrap cover material over the big holes to help keep the crap out'a the belly. Turns out that was a good brain fart.
 
Floorboards

So here are a couple of pictures of the floorboards. There are still a work in progress but you can see a little of the tightening up I was talking about. Just trying to make the holes that things go into as small as I can within reason.

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Nutplates again

I decided to nutplate the saddles for the rudder and brake pedals. It can be pretty challenging to get the spring, saddle, washer, and nut all together while on your back and working through an inspection opening with two fingers, so....while this was/is pretty over the top it should make future maintenance easier. It also saved 1/2 oz in case you are wondering.

So here is a saddle and a couple of the mini nutplates for the AN-3 (10-32)

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Nutplate positioned on the saddle. Note we took just a little off the corner of the nutplate to make it fit better. It is easier to see this in the next picture.
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There is no drill jig tool that I know of for this so you will have to use a bolt to hold the nutplate in position while you drill. I had a nut on the back side, its hard to see in this picture, but it made it easier to reuse it for all the saddles. Also the nut plate will shift ever so slightly when drilling the saddle for the rivets and as a result the bolt will bind up on the side of the saddle when it is going through to the nutplate. There are a couple of solutions to this. After the saddle is all drilled, open up the AN-3 hole by 1/16th inch. Or if you forget and find the problem after the nutplate is riveted on then you can run a tap in the hole part way (you don't want to go all the way or you will loose the "locking" feature). You can also very carefully open the hole with a dremel tool and grinder bit.

Here you can see the bolt, stop nut, and also the slightly angled ear on the nutplate. Ready for drilling.

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Drill baby, Drill. Seriously, a drill press is a well worth the investment. Even a bench top model will be very very handy. It is amazing how much easier it goes when using a drill press Vs a hand held drill. The drill just goes through the toughest metals sooooo much easier. Please consider it a worthwhile investment in your project.

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After you drill the first hole drop a rivet in the hole as an alignment pin. Don't squeeze it, you are just putting it in there to help keep things lined up while you drill the second hole. Looks like this.....

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Don't forget to clean up the edges of all the holes. With AL you can just spin a larger bit with your fingers, with steel you will have to use a drill, but don't get carried away. It only takes about 4 or 5 revolutions to clean things up.

It might look like this. Wear cloves to protect your fingers. Be careful folks. Spinning objects can remove flesh, fingernails, and even fingers.

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Countersink the rivets like this............

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And the finished product. There are 14 of these little saddles. It will pay dividends later. This is a delayed gratification thing.

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OK, that is about all I am going to say about how to do nutplates. You should be well on your way now.

Hope this is helping someone.

Bill
 
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Hi Bill

What are you doing for power distribution? Have you considered solid state? These (ZL-BP4) are simple, light, and adjustable to fit draw needs. Also take a look at their main buss (ZL-MB50).

http://www.ztronlabs.com/products.php


Take care,

Crash

P.S. I just TIG a high temp lock nut to the back of the tabs.
 
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Wow, hard to believe it has been a month since I posted on this. I have been busy with a trip to Front Sight and also to Alaska. Time to get cracking.

Crash - Thank you. Yes I will be using some Ztron products. Seems really good.

TRIM

If you are using electric trim you will want to have limit switches to stop the motor at the end of its travel to keep from frying the motor, wires, or popping CB's all the time. I used these on the last build and they worked great. They are Burgess V4LS micro switches. I attached them to the yoke by drilling and tapping for 4-40 screws. Drilling and tapping a hole is not that big of a deal folks. Get a Tap and Die set from Sears or where ever. You will use it often, even if just to clean up and clean out threads. So you drill a hole of the appropriate size, there will be a chart to tell you what size drill to use for a given tap, then you screw the tap in. Tapping a hole is kinda like drilling except you just go slower. There are all kinds of good instructional videos on you tube to learn about taps and making threads. Don't be intimidated. It is really not hard. So here is a picture of the tapping of the holes in the yoke for the switches. Note the tape wrapped around the tap. This is used so you know how deep you are going. Good for drills too.

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Don't forget that when drilling, tapping, and things like that you need to use some type of lubricant, cutting fluid etc. This is one that I like to use. Pretty widely available.

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And finally the finished product.

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Another thought. MMR (being the engineer he is) pointed out that it would be better to have the switches fixed and let the yoke move to them. This prevents the movement of the wires which can fatigue or be damaged. Good idea, but a little late for this build. You would want to have Jay weld on some tabs to attach the switches to. I did it backwards and I have tabs welded on for the stops. You would want to mount the switches to the frame and put the adjustable stops on the yoke. Either way will work (worked fine on my last cub) but this would be a better solution.
More trim stuff tonight.

Bill
 
Bill,
Did you tell us what your wing plans were? Recently I have been rigging my BackCountry Cub. One of the things which I have discovered is that there are about 4 degrees more down travel on the ailerons than up. I'm getting aprox 20 up and 24-25 down. Yes, I can restrict this with the stops except, that I like the idea of 20 degrees up. This differs from the Piper spec of 18 +/- 2 degrees for both up and down. Though it does fall within these numbers when using the +/-2 * with more down. The Piper spec implies that both up and down should be the same. I have rigged the ailerons to be neutral with the stick in the center. There does not seem to be any way to tweek it so that both are the same.

I measured the aileron horn pivot point in relation to the cable attach points. It is definitely set up to produce more down than up. This appears to be backwards to that which would reduce "adverse yaw". I would think that the aileron horn should be redesigned to allow more up in relation to down. The up horn can not be shortened for more up as the clearances are at a minimum now.

I would be interested to hear what others have to say about this. Is this the way that Piper did it?
 
I think mine worked out the same as yours mr sky wagon. I will be interested in any comments as well. Maybe they are meant to be drooped!
 
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