• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Building a Javron Cub

John,
How do you heat that large a piece of plexi enough to get a little bow in it? It will not fit in any oven which I have. Do you have access to a large oven/heat box? I agree that a little bow/bubble will stiffen it tremendously.
 
congrats Bill !!! the 12 Jay built for me also flew hands of on the first flight, all struts left to right set exactly the same. His efforts definitely show as my plane also has a very smooth soft feel to it! It would be great to do a comparison ride some day between your 18 and my 12.
HAVE FUN & FLY SAFE
Marc
 
Hi Bill,

What did you ever figure out and do relative to the installation of the Ztron master relay? Is it still installed as per your last posted photo of it?

Thanks

 
Keith

I did not use the Zetron but probably could have. I did not wire it quite the way you normally would. I will post on that when I get back home. No doubt this will be even better than the fuel selector discussion, yee-haa baby here we go. This is going to be quite a ride......

BILL
 
Got in a second short flight yesterday. the air was really smooth so I had a chance to check the rigging. Perfect. Dead on. still have some bugs to work on, like the left side windows are too thin. They are bowing in and out pretty bad. I will have to make a new set of windows out of thicker plexiglass. Heard about new sump that may save weight. Need to check on that. Its all good.

Bill
Great to hear it flys great. After a couple month long annual and weight loss program(cub, not me) I know how you feel when you get close to being done. Can't wait to get mine going. Hope to see yours soon.

febff795e9201302ac782e441fc18b9c.jpg


Tom
 
John,
How do you heat that large a piece of plexi enough to get a little bow in it? It will not fit in any oven which I have. Do you have access to a large oven/heat box? I agree that a little bow/bubble will stiffen it tremendously.

The last ones I did, I borrowed the propane grill from the local EAA chapter and fitted it with a small box made of sheetrock to hold the windows. (they were for a Stinson) You're only looking for about 315 degrees, so it isn't too tough to get enough heat. I've seen guys use a couple camp stoves ducted into a sheetrock "oven" and that worked just fine too. I just build a "mold" of MDF with the window cutout.
John
 
The last ones I did, I borrowed the propane grill from the local EAA chapter and fitted it with a small box made of sheetrock to hold the windows. (they were for a Stinson) You're only looking for about 315 degrees, so it isn't too tough to get enough heat. I've seen guys use a couple camp stoves ducted into a sheetrock "oven" and that worked just fine too. I just build a "mold" of MDF with the window cutout.
John

John,

Not to steal Bill's thunder here but I'm very interested in how you are doing the mold and the process in making the "bubble". Maybe we could move to Lowrider LSA thread to discuss.

Thanks!
 
Bill,
Sorry about the windows, that's kind of a pain. Cub Crafters used 34,973 hour glue on my window handles. Funny because Kelly wanted to take a few pics with out opening the door, slid my window back and boom, handle departed the plane. 10 seconds later Kelly said, "Well mine just came off too." Thinking it was still in her hand, mine was just a few feet shy of my fence line and I knew it could find it with just a little looking. Later, she informs me that no,,,,hers departed too. Without they sure are flimsy and a pain to fly with sliding open and rattling while waiting on the new ones. Pretty sure mine are 1/16, 1/8 would seem awfully think.

Surprisingly, CC only dinged me $25 each for the ends with the little L break that acts like a handle, I'm sure the center ones are less, just flat stiffeners with a seal to cut down on drafts. They fall just short of touching either track. Point is, I think you can stick with what you have, install without removal and have a good long term solution. Though I did learn from Pierce that putting some female velcro on helps hold them closed for hours without moving, if properly placed. Start small and add more if needed, inside and or out.

BTW, silicone is advised from CC and to use some blue tape during test fitting so the line is exact. I overfilled mine intentionally to make sure I had a good seal, also used 60 grit sandpaper to give a roughed up surface followed by a few alcohol wipes. (think if CC had done this they would have never departed. Really hard to push on with all that silicone in there but protect the track with a paper towel and add the female velcro as needed. Viola, works great, stays light. It's actually listed as an escape door in the POH. Place both hands in the middle and push, I'm certain it would work.

Bottom line, less than $80 bucks, keeps the light weight, escape hatch, and have something that functions well. KISS Here's a few pics of mine, let me know if you'd like a specific angle, or if this even helps at all.

IMG_3756.JPGIMG_3757.JPGIMG_3758.JPGIMG_3759.JPGIMG_3760.JPG
 

Attachments

  • IMG_3756.JPG
    IMG_3756.JPG
    1.5 MB · Views: 292
  • IMG_3757.JPG
    IMG_3757.JPG
    1.3 MB · Views: 251
  • IMG_3758.JPG
    IMG_3758.JPG
    1.3 MB · Views: 238
  • IMG_3759.JPG
    IMG_3759.JPG
    1.3 MB · Views: 263
  • IMG_3760.JPG
    IMG_3760.JPG
    1.6 MB · Views: 251
I used the CC handle / frame on the side window of my 12. I riveted it onto the plexi with soft 3/32 rivets (very gently!) and it hasn't given any trouble. I used .080 plexiglass.
 
Congrats Bill. You must be on Cloud 9. On the windows, you can make a channel like Piper did for the front and back of each slider which will make them stiff or you can buy the set from Cub Crafters for $100.
 
Great job Bill, If you are like most of us you will get a little ding on something, Please let us know when that happens so we know you are just normal like most of us. I made it about two months before I found the first hole in the fabric from a stray rock from the mower. Hoping you will never have to report anything. Enjoy and thanks for the post. Douten
 
Congrats Bill, it sure looks like a beauty. I know its been said before, but you sir are truly an inspiration to me, and I hope you dont mind that I have used you and your actions as examples for my kids and others. It had to be a low point in your life to watch your dream sink in that river to never be seen again. You shook that off, put your head down and never looked back and from your hands came an even nicer cub. We need more guys like you in this world. Really thrilled for you, well done

Jim Crane
 
Bill,
Great job, congrats. Your work and perseverance have paid off ten fold! Thanks for all the great pictures; they sure will help me finish my build. I'll try and use your model and post all I can as I finish my build. Now I have a "builders manual" I can follow so no more excuses from me! Thanks Bill.

Marty
 
This what I like about this site I had these photos I got from some ones post they did.image.jpgimage.jpg
 

Attachments

  • image.jpg
    image.jpg
    43.5 KB · Views: 188
  • image.jpg
    image.jpg
    52.3 KB · Views: 195
Bill--great job on the cub! Have you figured out a solution for the window? Larry's post above is a pretty good design. With the leading edge of the forward window longer and further from the support of the rear window it can definitely be an issue. Larry's design might work stand alone but I have seen of the longer sliding windows break including mine. What worked for me was to run the stiffener full length of the plexi into the top and bottom channel. I also used a wind deflector under the fairing ahead of the leading edge of the forward sliding window. Some not so great pics are in my gallery.
 
Folks - Thank you all for the window hints and tips and the kind words. I have not tackled that upgrade yet. Perhaps tomorrow. I do have the stiffeners on either end. My plexi is .093
I think, as Mark said above, part of the problem is without the fixed forward window, the panes are larger thus less rigid. You have given me several ideas on how to fix this "problem" so I'm pretty confident this will be resolved.

Jasperfield - Here we go......


P1030234.jpg

Main power (yellow) wire comes from + on the battery directly to the starter relay (black one in this photo). Then a wire from the same pole on the starter relay goes over to the master relay. The other side of the starter relay goes to the starter(yellow wire again). The starter relay has two other smaller poles. One labeled "S" goes to the start switch - this will be a positive current wire. The other pole is labeled "I" this goes to the starter also. (It is the white wire to the right side of the photo next to the yellow wire). This goes to the starter solenoid. Remove the factory supplied jumper wire. Be sure you can do this, some starters can not be wired this way.
Thus the master relay has current coming in from the battery via the starter relay pole wire, then the other large pole on the master relay goes to the main bus. The other two small poles are wired to each other from the factory and the left small pole (right in the picture) is wired to the master switch - which is then wired to the ground bus. So for the master relay all you are doing via the master switch is grounding the master relay. With this set up you are not pulling 600 amps through the master relay when starting the engine and thus the Z-tron relay can be used. I intend to replace the clunky, and heavy, old fashioned master relay with the Z-tron unit in the next few days. The old style master relay shown in the picture above requires close to one amp just to hold it closed. The Z-tron unit requires about .024W to hold open. Since my total amp draw is only around 4 amps that old relay is using close to 25% of my system right there. That is painful.
Another advantage to this wiring profile is less voltage drop to the starter due to loses at the master relay.

I'll answer this one up front. No - the starter relay is not hot all the time. You must turn on the master switch to get power to the start switch. You must then engage the start switch to get the starter relay to close and allow the current to flow to the starter and the starter solenoid.


Okay - flame suit on....

Bill
 
WOW Bill! I can not wait to see your bird!!!

I have my own Cub Crafter window story, only mine went out about 30 miles east north east of Yakima airport from 5,000 msl. I was not a happy man, so I understand your frustration with windows.
 
....I'll answer this one up front. No - the starter relay is not hot all the time. You must turn on the master switch to get power to the start switch. You must then engage the start switch to get the starter relay to close and allow the current to flow to the starter and the starter solenoid.


Okay - flame suit on....

Bill
Bill,
I beg to differ. if I understand completely and correctly your "leg bone connects to the knee bone" description. IF your starter relay "welds" itself closed you will not be able to remove the electricity from the starter. I have had this happen. The master relay must​ be able to remove the electricity from the starter relay.

The only starter relay electricity which you are able to control with the master relay is the "control" power to the starter relay.
 
Thank you, Bill,

That's an innovative solution to avoid large current through the master. I've been wondering about what you finally would do. I suppose that now the Ztron will be spared the heavy current and will work as designed.
 
Pete- I suppose you are correct. My understanding is that is how Beachcraft were wired. Piper and Cessna went through the master relay first. If it is, or was, a problem I'm sure it would have been corrected or highlighted. I'll try to do a little more homework, but my electrical guru seems to think he has never heard of a problem using this technique. I appreciate the input. I'll check on it.

Bill
 
Bill,
I have had several starter relays stick in the closed position leaving the starter turning the engine. Once with the engine running with the only clue being a strange noise and a pegged ammeter. The only way to stop the electricity was to turn off the master relay. This was in a Cessna 185.

The solution was to use a quality Cole-Hersee non-airplane relay. http://www.colehersee.com/
 
I interpret Bill’s starter circuit description the same way Skywagon does: if the Starter relay locks up, there would be no way to easily remove the power to the starter. I just don’t see this as a fatal flaw.

Here is an example of starter relay failure in such a system. In the Piper Tripacer, battery power is directly connected to the starter relay, as in Bill’s system. The master switch distributes power to all the other circuits. If the starter relay locks up, the starter continues to run. The one time this happened to me, I got out, removed the passenger seat, and disconnected a battery terminal. It was irritating but not a big deal. This is a rare problem that occurs on the ground with the plane not moving.

So the advantage of Bill’s system is that it eliminates a clunky relay that draws 1 Amp. The disadvantage is that should the starter relay fail (very unlikely) you would have to manually disconnect the battery.
 
I should also say that this is no fun when you are out in a lake on floats with the wind blowing you to an unfriendly shore! I'll take the relay that draws one amp thank you.
 
I've had the same thing happen in my Cessna. A friend and I flew into Fish Lake Idaho. When we started the plane to leave the starter contactor stuck and the only way to disengage it was to turn off the master contactor.

So we flew home with no electrical. That wasn't a problem, but leaving the starter engaged sure would have been.
 
first off, great looking plane!!!!!!!! , because of the fact you already have the mounting of (two) relays installed , "maybe" think about putting in another starter relay in "series" with the other one. and having the other elect things (lights radio ect.), being switched via a electronic switch . ... .. . IMHO-IMBW,i my humble opinion,i may be wrong . good day / rick
 
I would like to see some diagrams on wiring this all with wire sizes. I haven't look yet to see if there is a thread on this.
 
Folks - Have 6 hours on it now and a pretty fair "do list" including the possibility of re-wiring things and different fuel selector valve handle (but I admit those are not at the top of the list at the moment). The primary consideration right at the moment is getting a good break in on the engine so we have been running it pretty hard, and working on temps. My oil temp was running 130 and we have worked it up to 165, but need to continue to work on that. CHT's are always an issue and I have been working on that. 1 and 2 are fine in the 350 to 370 range. 3 was hot - running 415 to 418. I boxed the rear baffling which Christian Sturm reported on in this thread.....

http://www.supercub.org/forum/showt...-to-Reduce-CHT&p=541839&viewfull=1#post541839

and it is down to 380.

When I installed the Vans baffling I knew from my last build that #3 might run hot but I figured I'd try it as per the Vans plans and see. Sure enough #3 was running hot. So I boxed the #3 rear baffle and now #3 is down to 380. So a drop of about 35 degrees.

P10302331.jpg

This is standard Vans baffling behind #3. Note how it slants forward about 45 degree angle so it sits tight to the cyl.

P10302431.jpg

This is after the modification. You can still see the 45 degree line but you will note that the back baffle is pretty much straight down then a 90 degree turn toward the cyl at the bottom. This creates about a 1 3/4" space behind the cyl before it gets to the bottom where the curved part fits up tight to the bottom of the cyl. This "box" is the way the Supercub Baffling is made. Vans is a good, cheap option, for homebuilders but this is an area where it needs to be modified. I suspect it works fine on the RV airplanes that are going 200 MPH but it is not so good for 95 MPH Cubs. Don't know why this mod works but it does. There is more info and validation in the thread referenced above.


P10302392.jpg

This is my back panel after the mod. Again, folks there is more info in the thread above, but if you are using the Vans baffling you might need this mod. If your #3 is running hot check your baffling for this box. It is worth 35 degrees for most folks.

So, now #4 is the hot one running about 385 to 390 and oil temp is too cool. I suspect the air is taking the path of least resistance through the oil cooler thus the cyl is "relatively" hot and the oil too cool. So we are slowly blocking the oil cooler off which is changing the air flow and raising the oil temp and lowering the CHT. I am getting there but it takes a little time. Also temps may come down more when the rings seat, probably in the next couple of flight hours.

Still trying to get the GRT all set up. I messed up the fuel calibration on the left probe so will have to get that straight. I think it is going to work GREAT when it is all set up. Hey, DW - I changed the drain on the gascolator. Thanks. Got some 1/8" plexiglass and will make some new windows tomorrow. My first version of windows was .090 and too thin for the extended window. (They call it 1/8th but it is really 3 mil which is closer to .120) What....e....v....e....r. It is thicker than the last stuff and with a couple of mods to the stiffeners that should do it. I'll report on that when done.

The Grove breaks are great. Love em. The trim works great even at 130 MPH (with the 74-60 prop and 2500RPM that is what we sometimes see) going like a scalded ape even with the big tires. I am actually looking forward to the Catto prop and speeds of 95 MPH. Cubs just aren't made to go that fast.


Hope this helps

Bill
 
Last edited:
Folks

Here is a weight and balance form in pdf that will work well for the FAA inspection and it is also a pretty good format to run several scenarios, then keep in the plane.

Also there is a pdf of the "Program Letter" that you will need to submit to request the final inspection from your FAA representative. You MUST have your registration in hand before you submit this letter. You can pretty much do the registration anytime, so about 4 months from completion get it registered. Then a month or so out start trying to line up an inspection. If the FAA can't (or won't) do it you can get a DAR to do it. The FAA guy is free, so I would try for that first. The DAR may cost up to 500 dollars. Most all the other forms listed in the program letter are available at the FAA website except this program letter, thus in an effort to help my fellow Cub guys, here ya go.

You can download these files and print them out on your printer.

Hope this helps

Bill
 

Attachments

  • AcftWtBal.pdf
    303.8 KB · Views: 604
  • ProgramLetter-Blank.pdf
    587 KB · Views: 500
Thanks Bill I'll sleep better tonight knowing I can borrow gas from you at JC........
 
Back
Top