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Thread: Building a Javron Cub

  1. #561

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    Quote Originally Posted by skywagon8a View Post
    It would not matter what type of airplane you were flying. Take a look at a map of Canada. Look specifically at the terrain between Timmons Ontario and High Level Alberta. It is all the same. Just saying that it was very fatiguing without the autopilot.
    Hey! Some of the most scenic prairie, pothole wetlands, grain fields in the world. No mountains to get in the way of a good view. What do you mean?

  2. #562
    Bill Rusk's Avatar
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    Autopilot Considerations

    I went to the Alaska Trade Show and had a great time but other than getting a few ideas not much has been accomplished on the build. However, I have had time to consider the Autopilot issue. This is not an easy choice. There are some advantages and some disadvantages. I will try to give you some of my thought process so you may consider this in your build as well. I have chosen to not put in the autopilot on this build. It really gets back to my rule, which I have expounded on before.....

    "Build For 90%" or the "90% Rule".

    Take an honest look at your expected flying, (past performance is the best predictor of future performance) and build the airplane for what you will do 90% of the time. For the vast majority of us, with Cubs, if we fly 100 hours in a year most of that time is spent fooling around the local area. Patterns, giving a 25 minute ride, maybe a local hamburger or visit with a friend at a nearby airport to see his new panel etc. Part of the dilemma with Cubs is that we all see ourselves taking that big trip to Northern Canada around Hudson Bay, and Alaska, and that becomes the driving focus. Me too. And I do hope to do that. Hopefully more than once. But the reality is we make that trip once. So over a five year period of ownership we fly 500 hours (obviously this will vary but it usually starts out high and goes down ie the first year we own our cub we fly 200 hours, then the next year it is closer to 150, then 100 then we settle at between 50 and 100 hours a year.)
    In that 5 year period we go to Alaska and put 50 hours on the plane for that trip. That is 10%. The other 450 hours are spent messing around the local area. If I add all the extra fuel tanks, GeeWiz gadgets, and everything else to make that Alaska trip great I have built for 10% of my flying, not 90%. Better to have a plane that is perfect 90% of the time and less than perfect 10% of the time. A big part of that is weight. Light Cubs are more fun to play around the local area in. I personally hope to spend more than the average time in Alaska and Canada but the reality is.........

    Sometimes we can compromise. A fuel/cargo pod is a perfect example. Rather than put 72 gallon tanks in the wings, which you drag around "ALL" the time, I can put a fuel pod on just for that trip to AK then take it off when just messing around the local area. Plus it keeps the weight low so you are less likely to stand the plane on its nose. All that fuel(weight) wants to go forward and down when you brake. Pretty tough to take the autopilot in and out.

    If you anticipate spending a lot of time in cruise then the autopilot would be a great addition. Man it is nice to be able to eat lunch, take a picture, or sight see without recovering from unusual attitudes. In a former life I would give a student an unusual attitude then say "ReeeCoverrr" I often think of that after looking at a chart for a few seconds, or digging my water bottle out. An autopilot would make longer days possible due to the reduced fatigue. Three, 3 hour legs in a day would be a piece of cake. Lou is a perfect example of this. He has taken some monumental X/C trips in his cub and the autopilot has been a big part of that. So, it certainly has its advantages.

    Weight. My guess is close to 10 pounds. Turns out we (Super Cubs) need the hi torque servos. They weigh 3.3 pounds. There are some new servos out now that weigh as little as 1.5 pounds but everyone I have spoken to says it took the Hi- Torque models to make it work. Cub Crafters has put in somewhere around 10 autopilots. They have pretty much settled on Tru-Trak. They have pretty well figured out how to make it work. My understanding is that it is much more successful on the round tip wing Vs the square tip. The difference in stability about the vertical axis makes it tough to minimize the dutch roll, from what I have been told. In my case, with the GRT efis (Grand Rapids flight display) which has the autopilot built in, I would have to use their (GRT) servos which are 3.3 pounds and a close imitation of the Tru-Trak model. Or I would have to add the controller from whatever servo company I chose. This adds to both the complexity and weight.
    In addition to the servos, there would be weight from the mounting tabs, and hardware, and also the pushrods with rod end bearings on each end and the wiring. My best guess about 10 pounds.

    Another issue which has gotten better (tec improvements again) is the issue of the drag on the controls from the autopilot servos even when disengaged. You are pushing (rotating) that motor in the servo every time you move the controls and that can be felt in the stick. Not huge, and has gotten better, but it is still there. I like my controls to be totally free, almost sloppy loose. I can feel the airplane better, and the wind, and it makes a difference when operating on the edge of the performance envelope. Again if you think a large part of your flying will be X/C and not around the edges of the envelope this falls back to the 90% rule. Will I be on the edge 90% of the time? Well, I hope not, but I do tend to play around there even just messing around the pattern. Thats the fun stuff for me.

    I have elected to use the B&C case mounted generator so current draw is an issue. The autopilot takes about 2 amps draw. Given that at cruise I have a MAX of 8 amps, and I have a current drawing glass panel, I would probably be pushing my electrical capacity pretty hard. So, if I upgrade my electrical system to handle the autopilot that adds considerable weight. If you are running a standard alternator this would not be a factor for you.

    Randy suggested I put in the mount points so it could be added later if I changed my mind. This is an excellent consideration and I have used this concept before. In this case it is not that simple as each installation is different depending on servo selection so I do not think it would be possible for me, but I offer that idea for your consideration, and certainly it is a great concept to keep in mind for other aspects of your build.

    In summary, no autopilot for this build. Is that choice optimal for you, and your Cub? Only you can make that choice and that is one of the great things about building your own airplane. It will be YOUR perfect Cub.

    Hope this helps

    Bill
    Very Blessed.

  3. #563
    Bugs66's Avatar
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    Interesting Bill, thanks for the info. I have 44 gal usable in my Cub and am glad I do. You don't have to fill the tanks if you don't want to but is really nice to have the extra capacity without needing to strap on the tank pod. For me this is important because I run mogas almost 100% of the time. Often where I am going there is no E0 mogas so I rely on what I bring with me. The more I can burn mogas the more I save. I also have the ABW fuel bags which I can throw in for addl 10 gals when I need it. The wings have a lot of empty space and why not take advantage of that with fuel capacity? Is it easy to transfer fuel from the pod to wing tanks, or require a pumps and gear? Just some more thoughts.

  4. #564
    Iflylower's Avatar
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    Bill, good to see you posting after the show. Use that show momentum for a quantum leap forward. I think you wanted to fly to the show next year??

    Btw, good pics of the trade show. I hated to miss, but too much juggling. I would've loved to see Randy's carbon wares among other things. I'm with you on detachable fuel range.


    B&C has a shorty 20amp and plane power has a 30amp alt for the vacuum pump acces. hole. Possibly a little more amp margin if you're running the system, recharging main battery, running CRT's, strobes, nav's, iPad, gps, charging cell phone, etc. (You know your design needs, not me) FAA 43.13 rule is to keep design under 80% alt load. Anyway, you know that, but that extra elec could come in handy for running it all in the Canadian outback. If your design maxes under 6.4 amps, go for it. I looked at the 8 amper and like it. Even with all LED's, I couldn't pull it off. Speaking of batteries, there are some great weight saving options these days.....


    Love the progress
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  5. #565
    Cubus Maximus's Avatar
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    Bill, you could always put in a Boyington "autopilot" for the long stretches. Simple and lightweight...

    (Pappy rigged up a set of strings and rubber bands attached to the Corsair's stick so he could doze on long range fighter sweeps out of Bougainville)

  6. #566
    mvivion's Avatar
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    George Kitchen, an old time cub driver out of ANC and Sand Point used to rig up his "rubber band autopilot" when flying between Sand Pointand ANC. Worked great and weighed next to nothing.....

    First time he told me about it, I thought he was joking......he wasn't.
    MTV

  7. #567

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    Bill,i agree with you 100% if you don't need it on 90% or more of your flying you don't need it. to add an auto pilot would not only add weight but also another maintenance item. the same goes with long range fuel tanks, you are adding the weight and maint of tanks lines and pumps. my TCOW 12 came with 48gal they have the option for 82gal. how often does anyone flying for personel use ever need that much fuel?the belly tank is a great idea, if your on floats put some cans in the hatches.

  8. #568
    windy's Avatar
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    Bill, you said it so well about the 90% use. BTW I keep a camelback strapped to the back of the front seat to not have to dig for a water bottle. smaller sips mean less urgent pee stops

  9. #569
    Roger Peterson's Avatar
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    That is what is so great about expermental. You can do it anyway you want, there is no right or wrong.
    For me, half the fun is playing with all the new gadgets. Great job Bill, Hope to see you this summer.

  10. #570
    Bill Rusk's Avatar
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    Folks

    Boot Cowl - You might be better off letting Jay build it (which he does) as part of the kit. I have spent too much time on this. So, in hindsight, there are two areas I would probably rethink if I were to do this all over. Put in the shelf to lay the floor boards on rather than using the lower longerons. Yes it will save a couple of pounds and it gives you a little more baggage room but it takes a lot more time to put together to save the two pounds. Lightweight costs both in time and money. In each case there is probably a point of diminishing returns. The boot cowl is another case of diminishing returns. The titanium firewall saves 2 pounds but it takes a lot of time to build. (or it did for me. Some of you craftsmen out there can knock one out in a couple of days but for us amateures it takes a little longer and in my case a LOT longer.

    But to show those of you doing this a little more info (reference some info on this topic already posted in this thread)....


    These are some of the steel parts that are part of the cowl brace rod attach fittings


    Note the deep scratch marks on the left side of the edge. These are also referred to as tool marks. They were caused by the bandsaw. These are stress risers and can cause a crack to propagate from this area. It is a good practice to (file or sand) remove these tool marks from all your metal parts, as in the right half of the edge shown above. I sanded just that half to show you the difference and to make this point.


    Be sure to clamp your work when drilling. It is not safe to hand hold and drill. The drill can bind in the hole and spin the part in your hand possibly causing a serious injury, like the loss of a finger. It takes longer but .....THINK........use your head and lets be safe out there.


    This is the lower cowl brace rod attach fitting on the lower part of the firewall.


    This is the reinforcing brace on the backside of the firewall. There are 4 of these. One for each brace on each of the 4 corners. Note - one rivet not yet squeezed, and also these are normally held on with #10 Truss head screws not AN3's but that is what I was using to fit things together in this phase.


    Another trick. You can spray small parts over the trash can and it will contain most of the overspray. Be sure to pull the glove over your watch.


    I have said this before but it is worth repeating. Note that the rivet set is hitting the nut-plate. Don't be afraid to modify your tools. If you end up buying a few tools to replace the ones you modified.....well that is just part of the cost to build an airplane.


    Note that I sanded a little off the rivet set and it now clears the nutplate just fine.


    Although you can't see it very well.....In this case I took and AN3 bolt and sanded it to the shape I wanted (to fit in the channel for the boot cowl brace) and used that for a rivet set.


    Behind each of the cowl attach fittings is a brace. You can see the three rivets holding it on here.


    This is what it looks like from inside the boot cowl

    More to follow

    Bill
    Last edited by Bill Rusk; 05-18-2013 at 08:53 PM.
    Very Blessed.

  11. #571
    RaisedByWolves's Avatar
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    Great job bill, I look forward to your write ups. Keep at it!

  12. #572
    Bill Rusk's Avatar
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    This is the lower cowl brace rod where it attaches to the nose bowl.



    Take the time to get your nose bowl positioned where you want it. If you put it a little low (note that the prop flange is not centered in the hole in the nose bowl) it will help your over the nose visibility and also give you a little room for the engine to sag over the years. Just a technique. Make it look good to your eye. In general there should be a nice smooth descending line from the instrument panel to the top of the nose bowl. Clamp it down good so it does not move while you are building the cowling.


    Side view of the cowl brace rods.


    Cowl door coming together. Note the descending line under the long ruler. I lowered the engine 2 inches to get the built in Thrustline mod "kink" out. Jay built my engine mount this way and he is jigged so he can build others this way as well.




    I pretty much used the plans from Christian Sturms site for all of this. I just print the drawing I need on an 81/2x11 sheet of paper and take it to the hangar. Follow the drawings with some allowances for differences. For example the nosebowl for the 180 Hp 0-360 is a little larger than the 0-320 nose so the dimensions may need a little tweaking to make it all work out. Just keep it all square and watch out for parallelograms.

    Hope this helps

    Bill
    Very Blessed.

  13. #573
    mike mcs repair's Avatar
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    Quote Originally Posted by Bill Rusk View Post

    Note the descending line under the long ruler.
    Bill

    ??? descending line under the long ruler. ???

  14. #574

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    Take out the windshield strip, the ruler will lay perfect,it looks real nice. That will be sharp looking when done. Does Your mount moves the engine a full 2 inches down and did you move it back any? Bill is jay putting out his wing kits yet? Very nice.
    Last edited by tempdoug; 05-19-2013 at 08:58 AM.

  15. #575
    Steve Pierce's Avatar
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    Bill, How did your bootcowl skins fit on the fluted firewall? I did not like the gaps around the flutes and opted to cut the lip off and bought a PA18 firewall flange from Clyde Smith and riveted in with some PRC to seal it. Don't want oil and stuff seeping in.





    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  16. #576
    Bill Rusk's Avatar
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    Steve

    I like your idea better. I managed to make it work but it was a pain. I used Flamemaster CS1900 sealant between the firewall and the top piece.

    Bill
    Very Blessed.

  17. #577

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    Bill, It all looks great. Keep posting, it is really helping me with my project. Appreciate all the post from all of you great builders out there. Greg

  18. #578

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    Click image for larger version. 

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    Bill, here is sortve a neat baffling plenum idea. No air leaks and no seals.

  19. #579
    Dave Calkins's Avatar
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    If doing a plenum, make sure it installs and removes easily.

    The early Cessna 170 models had a plenum and it was fastened with Dzus 1/4 turn fastener's for easy access to stuff.(spark plugs and leads, in our case here, oil pressure relief)

    A great way to save weight would be to substitute carbon fiber for aluminum in this application.....save half the weight of the metal!

    Plenum or not, make sure to pay attention to EVERY gap on the low side of the "pressure area", i.e., around the alternator brace and belt, around the junction of aft baffling/crankcase, intercylinder baffles, front and rear lower baffle/cylinder junction, rear baffle to accessory case.

    The losses of seal and resulting "easy" airpaths have overheated more than one hotrod engine in a Cub. Wayne Mackey has done aLOT to optimize this point!

  20. #580

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    Nutplates?

  21. #581
    Darrel Starr's Avatar
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    I have found that at Super Cub speeds, the openings in the front of the lower cowl matter very little. I have very tight baffle seals and very leaky front lower cowl openings. Doesn't seem to matter how much I open up or seal the front of the bottom cowl, the engine runs fine with good cooling. Though what I do get is a puffing up of the top sheet of the top cowl at cruise -- makes me wish I had wider cheek openings at the back of the side doors to let the air out or a lip at the back of the lower cowl. But why bother when the temps are 350F CHT and 1350 EGT.

  22. #582
    Bill Rusk's Avatar
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    Tempdoug - Lowered 2 inches and built in Thrustline mod, but I did not try to move it back any. I felt it would make maint harder and might also eliminate the use of some exhaust systems. With all the lightweight engine accessories and props I am not really worried about my CG at this point.

    Darrel - I agree that cooling is generally not a problem with "normal" engines but if these guys are going to use a "hotrodded" engine it can be a problem. They have had to work pretty hard to get the temps under control on the CC with the 0-340, and on other airplanes with the 0-375's etc. Sounds like your numbers are spot on. I had some problems with my last hotrodded 0-320 but this time my 0-360 is pretty close to stock so I don't anticipate needing a plenum. I also agree that the rear edge of the top cowl needs a couple of fasteners and I will put those in. My cheeks were a little undersized and tight on the last one so I will make them a little larger on this one per your input above.

    Wings - I had asked Jay to look into drilling out the wing spars to save weight. This is pretty popular with the Portland crowd and they have not had any wing failures, nor do I know of any in the CC fleet so it obviously works. I believe the savings to be around 2.5 pounds. I have also spoken to a couple of folks who expressed their opinion that a drilled spar wing may not hold up as well under non flight related stress. Alder tree impact, mild groundloops, hangar rash etc. Things that would not normally do much damage to a stock wing, supposedly crumpled a drilled wing pretty good. I do not have any hard data to support any of this at this time.
    However, the new ribs, spar drilling, and a couple of other things, have delayed the Javron wing. Jay has been trying to accommodate my requests in this area and so, a big part of the holdup, has been my fault. Sorry folks. Jay has decided to move forward with the wing using a standard undrilled spar at this time so I expect the wings to come together pretty soon. I know the ribs are finalized and being produced now. I believe Jay has one more wing test to run and once satisfied with that things should go pretty quick. As soon as I have data I'll post it here. I believe the wings will be excellent - strong, true, and quite a bit lighter than the other wing options (excluding the CC wing) available at this time. It is my understanding that Jay intends to offer the wings in either kit form and/or fully assembled when it is all said and done. This might be a great option for the guys scratch building.

    Hope this helps

    Bill
    Very Blessed.

  23. #583
    skywagon8a's Avatar
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    Bill,
    I agree with Darrel. The cheek openings on mine are 2-5/8". I can feel the heat by placing my hand on the inside of the fabric next to the door (no interior). I also left out the baffle which seals between the air filter and air box, just to see what happens. Do not need it. My temperatures are perfect in the middle 300s. I do not have the same problem with the top leading edge puffing up, but I do have looseness in the aft end of the top cowl. I did manage to reduce this by doubling up on anti chafe materiel. I guess that I did not hold down the aft end tight enough when I was drilling holes. Letting the hot air out is as important as getting the cold air in.
    N1PA

  24. #584
    Darrel Starr's Avatar
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    I also left off the little nuisance plate around the carburetor. I noticed one year at Oshkosh that Cubcrafters didn't bother to close off that area either.

  25. #585
    cgoldy's Avatar
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    Do you mean the vertival plate behind the filter? Wouldn't that pressurise the low pressure side? Or is there a horizontal plate around the carburettor that I don't know about?
    Javron O-375 wide body extended wing cub

  26. #586
    Bill Rusk's Avatar
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    On my last cub I tried a before and after test of blocking the filter/carb area. Yes, theoretically, leaving it open should pressurize the low pressure side, but I could not see any change in engine parameters with or without blocking off this area.

    Bill
    Very Blessed.

  27. #587
    skywagon8a's Avatar
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    Quote Originally Posted by cgoldy View Post
    Do you mean the vertival plate behind the filter? Wouldn't that pressurise the low pressure side? Or is there a horizontal plate around the carburettor that I don't know about?
    Yes, that is the plate. It doesn't seem to do any harm by leaving it out. It may even help cool the oil a bit.
    N1PA

  28. #588
    cgoldy's Avatar
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    Man that plate is a pain. I finally worked out how to work around the filter. I have a sutton exhaust and to get the lower cowl over the exhaust and threaded onto the filter spigot was imposible. So I cut the spigot off and made it removable by welding a nut on the end and a bolt on the air box. Works a treat. now I have been able to seal the back of the filter to my liking.
    Javron O-375 wide body extended wing cub

  29. #589
    cgoldy's Avatar
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    That all does not make sense to me. We go to great lengths to get air out of that area! Maybe it works as some sort of venturi?
    Javron O-375 wide body extended wing cub

  30. #590
    Darrel Starr's Avatar
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    CubCrafters Top Cub at Oshkosh in 2006 -- no plate around the carb air box.
    Click image for larger version. 

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    Here is another Top Cub
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    Our Super Cub, N18SY, during rebuild. I like the big hole for the ring gear/starter -- makes it easier to time the mags. The air box where the oil cooler used to be provides fresh air to my feet through the "rear seat" heater ducting in the summer with some ducting rerouting -- lots of leakage around the black air box too. The plate around the carburetor intake is not installed.
    Click image for larger version. 

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    Last edited by Darrel Starr; 05-21-2013 at 09:56 PM.

  31. #591
    Bill Rusk's Avatar
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    Working down the "do list" prior to covering the fuselage.



    Be sure to rig and check your elevator cables. Mine were not the correct length. I did a lot of head scratching, figured out I could fix the problem by using different turnbuckle parts. THEN after much grief (and a few words I should not be using) I discovered I had the cables hooked up backwards. I never cease to amaze myself. So.....the cables are fine. Jay does good work. But I did note the elevator was hitting the bracket a little prematurely and thus I was not getting full up elevator. You can see that the attach tab extends well aft of the control horn. No problem. I reshaped it so it looks like this ..........


    Whaaala.......full up elevator now.


    The rudder cables will fit through the furles from back to front only. You will want to install these prior to cover, otherwise you will have to cut out your access covers before you want to.


    You may have to clean up the powder coating a little to get the cable guides in.


    Post clean up. Don't forget to primer and paint the inside of this guide before the plastic insert is put in, otherwise it will rust. A quick thought on primer. Most primers are porous and as such the metal will rust right through the primer. It will slow it down a little but primer alone is not a rust preventative. Variprime is an excellent product but it is very porous. You must paint over it to get true rust prevention. I like and use an epoxy primer PPG DP40. This is MUCH less porous than Variprime and though you should probably topcoat it you can definitely get away with it alone as the porosity of this product is extremely low. It comes in several colors. I recommend the white color. Topcoats better.


    I found a little welding slag in this guide so used the Dremel tool with a grinding bit to clean it up. Another thought if I may. Folks, do not expect the kit you purchase to be perfect, regardless of where, or from whom, you get it. You are building an airplane not assembling a Lego
    toy. Every kit will have some issues. That is part of the building. Javron is awesome and his attention to detail is great but this is a BIG project and I sometimes hear stories from guys that think it should just assemble with everything perfect the first time. Maybe, if a manufacturer put out a 100,000 kits and all were exactly alike (no customization at all) they could get it down better, but the reality is each kit is different due to the customization and thus it may not be perfect. I am extremely pleased with my kit but I don't want folks to get unrealistic expectations that this is going to be an easy weekend project. It is quite doable for the average person, just go slow and take it one step at a time.

    As my neighbor says......I liked his saying and I adopted it.....

    Its just a series of problems to be solved


    I would prefer to use a reamer to clean out the holes but sometimes you just can't get one in there.........
    Sometimes you have to remind yourself you are not building a space shuttle.......like a lot of builders I tend to be pretty picky and try to do my best, thus I get stressed when I feel like I am not doing it PERFECTLY, thus I sometimes have to remind myself.....
    its not a space ship.......


    I do recommend you use a reamer whenever you can......its just better......


    The rudder horn is on the stop but there is a lot more possible travel before it interferes with the elevator, so........


    Whip out the die grinder with a cut off wheel and get as much rudder travel as possible. You only need about an inch of clearance between the rudder and elevator. It slips much better with lots of rudder travel. If you get a little too happy and overshoot and cut too much of the stop tube off, you can tap the inside of the tube and insert a bolt or screw to increase the length back out.

    Hope this helps

    Bill
    Very Blessed.

  32. #592
    spinner2's Avatar
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    Great posts Bill along with pictures showing exactly what you're referring to. Almost like a Builders Manual.

    I like the end of this last post where you are shortening the rudder horn stops. More travel is better. I did that on my EX too. But the flip side of this is that with some kits you don't want to shorten the stops so much that the rudder pedal hits the inside of the firewall at full travel. That was a possibility with mine.

    So you must be back home now from God's Country?
    "Fast is fine, but accuracy is everything." Wyatt Earp
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  33. #593

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    Bill when changing the control stops for additional clearance from the original specs could you be introducing the potential to induce a stalling of the control by exceeding it's critical angle of attack? I don't know if my question is relevant here as you may just be adjusting the stop to meet specs but you did say "as much rudder travel as possible" and I wonder if the original designers had them limited on purpose?

  34. #594
    Steve Pierce's Avatar
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    Quote Originally Posted by Darrel Starr View Post
    I also left off the little nuisance plate around the carburetor. I noticed one year at Oshkosh that Cubcrafters didn't bother to close off that area either.
    I retained the rear plate and added an extra hinge so it was easier to remove the lower cowling with the Sutton exhaust.

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    Steve Pierce

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  35. #595
    Steve Pierce's Avatar
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    Quote Originally Posted by Bill Rusk View Post



    Be sure to rig and check your elevator cables. Mine were not the correct length. I did a lot of head scratching, figured out I could fix the problem by using different turnbuckle parts. THEN after much grief (and a few words I should not be using) I discovered I had the cables hooked up backwards. I never cease to amaze myself. So.....the cables are fine. Jay does good work. But I did note the elevator was hitting the bracket a little prematurely and thus I was not getting full up elevator. You can see that the attach tab extends well aft of the control horn. No problem. I reshaped it so it looks like this ..........


    Whaaala.......full up elevator now.
    Bill, That tab acts as your elevator stop. It is flat like that so the whole thing contacts the tab in the fuselage and doesn't wear down over the years with use.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  36. #596
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    qsmx440 - I have not found any problems increasing the elevator or rudder travel so far. It is an experiment so to speak, but also the certified airplanes can be pretty conservative sometimes. I did the same on my last cub and had no adverse handling issues at all. (excluding water entry)

    Steve - very nice carb air box idea. Slick. Thanks for the input on the elevator horn. Mine is now shaped so that all three parts, 2x horns and 1 bracket all hit the backstop together. I think it will be good. It gives me 28 degrees up travel Vs the book value of 25 degrees. Folks - just because I am doing things a certain way does not necessarily make it right. I appreciate the inputs to let others know there are other ways to do things and the logic behind those ideas. Sometimes I don't always give enough info when I deviate from the tried and true methods.

    Spinner2 - I'll be back ASAP

    Bill
    Very Blessed.

  37. #597
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    Some of us like so much rudder and elevator travel that we make them bigger than the stock ones.

    Bill, the white primer in the DP series is not as good for rust preventative as the others in that series. It is lacking some of the good stuff that the green, red, and "yellow" DP primers have. Sorry to tell you this.

    Also, the so called "Boeing Primer" such as "Crown Metro" or "Axxon" or "Super Koropon" are much, much less porous than the DP series and I would not consider using the DP stuff for its' "epoxy primer" qualities unless it is topcoated.........the "Boeing Primer"-types are excellent without a topcoat.............. FYI.

  38. #598
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    Quote Originally Posted by qsmx440 View Post
    Bill when changing the control stops for additional clearance from the original specs could you be introducing the potential to induce a stalling of the control by exceeding it's critical angle of attack? I don't know if my question is relevant here as you may just be adjusting the stop to meet specs but you did say "as much rudder travel as possible" and I wonder if the original designers had them limited on purpose?
    There is a test for "rudder lock" which is done on multi engine airplanes. It is an asymmetrical thrust situation and not something that is likely to be found on single engine planes. The test looks for air pressure reversal which pushes the rudder against the stop, thus holding it against the stop. This is not allowed under modern regulations.

    I do believe that the primary reason for the rudder stops is to keep the rudder from hitting the elevators.
    N1PA

  39. #599
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    Dave - I was surprised to hear that the other colors of the DP series of primers are better than the white as rust preventatives. I called the tech rep at PPG this morning and asked that very question. He assured me that the ONLY difference between the primers is the tint. They have exactly the same chemicals, in the same proportions, one to another except the tint/color. Your experience may prove otherwise but that is what the manufacturer says.

    I am very interested in the other primers you spoke of and will be doing my homework on those. Always looking for better products. Thanks for the info. Lets see what the RV forums say. They call them the "primer wars" over there as there are so many threads and "discussions" on this topic in that community. Hehehe - this could get interesting.....


    Bill
    Last edited by Bill Rusk; 05-30-2013 at 06:01 PM.
    Very Blessed.

  40. #600
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    Wow!! What a thread. Most excellent attention to detail

    “We sleep safely in our beds because rough men stand ready in the night to visit violence on those who would do us harm.”

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