zadwit

Members
  • Content count

    236
  • Joined

  • Last visited


Community Reputation

88 Excellent

About zadwit

  • Rank
    Advanced Member

Recent Profile Visitors


1,078 profile views

zadwit's Activity

  1. zadwit added a post in a topic kitfox 4 with 582 flying   

    I wrapped the muffler can and hot air outlet hose nd the inlet stack with HD tin foil and used safety wire to secure it.... I will probably remove the tin foil this summer when it warms up....but every little bit make a difference...
    • 1
  2. zadwit added a post in a topic kitfox 4 with 582 flying   

    Thank Lenni.... I still have trouble with video stuff... Yup thats it.... The heater works great... IF I did anything to improve, Id take the fibreglass stove door seal material and make a spiral around the muffler can and force the air to swirl around muffler to get a little more heat.. .On climbe the heater air was hot, on cruise, it cools some but lots of airpressure in that cowl so that was part of it.. all in all it made it warmer in the cockpit... even though a lot of the air is blasting under the seat on my side,,,,so I need to seal up the area under the seat a little bit.....THe AOA is a neat little gadget, not sure how much or if Ill use it as I have a very accurate AS indicator and this plane that TOm built is very predictable and a true joy to fly.....IT does perform better with my 72" Aerolux prop, shorter takeoff, faster climb and faster cruise and WAY WAY smoother prop.. most 2 blades are rough running but not the Aerolux


    • 0
  3. zadwit added a topic in Avidfoxflyers General Hangar   

    kitfox 4 with 582 flying
    try this
    https://youtu.be/kHAHEVKJEds
     
    I installed hot air muffler cabin heat, works great, LRI (AOA) on top dash, Garmin G-5 tied to my Garmin Aera 660 for navigation, electric carb heaters (for carb anti ice), electric fuel pump, and LED mav lights. PUt my old Warp drive 3 blade 68" prop back on, my 2 blade is faster in cruise, and almost identical in climb..about 1000 fpm at 60mph
    kHAHeVKJEds[1]
    • 8 replies
    • 106 views
  4. zadwit added a post in a topic Vertical rudder tube issue   

    Ideally you want the tail spring to take the shock loads. That is why I never was a big proponent of installing stiffer tail springs on Super Cubs. Those that did ended up putting more stress on the tubes in the tail area and eventually something would bend or crack.....
    IN the case of the Avid, maybe someone dropped the tail in the past or got it to crow hopping on the runway or ran the tail thru a ditch, who knows... the poor tail wheel takes a beating... solid rubber tailwheels add more stress, pneumatic tail wheel tires take up some shock.....
    I wouldnt be worried about it Vance, it is just a light weight structure but is you beef it up just a little, it will put the stresses back on the tail spring which is what you want...
    About the only tubing primer I ever saw that could stand up to MEK based fabric coating systems was stits epoxy tubing primer, (green). There might be others out there but I know Stits works, spendy but works...
    • 1
  5. zadwit added a post in a topic Vertical rudder tube issue   

    Weld in two tube ,about 3/8" or 7/16" OD from the center of the bend in the vertical fin post to the center of the lower longeron bays. THis will stiffen it a little bit. Ive seen the same thing super cubs in Alaska and that is how we fixed it....YOu dont need large tubes, just small one to add a little strength in the middle of  the long spans...
    If you tig weld, have a spotter  with fire extinguisher in case you catch the adjacent fabric on fire.... Gas welding is easier for me but what ever you are comfortable with.
    GLue on a patch with poly tak, let it dry, shrink it , apply the primer coat(poly brush) and the silver (poly spray ) and top coat and your done! OR what ever coating system you use. If the old fabric has enamel, try to clean it off with MEK so you can get a good glue bond with the poly tak...
    • 0
  6. zadwit added a post in a topic Another Flapperon Failure   

    YOur absolutely correct......if it looks iffy at all, replace it. That way when you are up in the air you wont be as concerned about it.....
    • 0
  7. zadwit added a post in a topic Another Flapperon Failure   

    Its not the lift strut rod end I am concerned about. It is the welded in stud that the FEMALE rod end attachs to. This is on some of the early model 4 kitfoxes. I see the factory change and started using a MALE rod end that threads into the end of the lift strut. The earlier style is the one that worries me. It has CUT threads placed under tension....not good.
    THis silver strut has a stud welded into the strut end and a FEMALE rod end threads onto it....The threads are CUT threads...The aviation industry learned all about cut threads on Piper lift strut forks when Univair made replace forks with cut threads. Even the rolled piper threads failed after so many cycles and hours so finally Piper came out with a lift strut that had a really large diamer HD strut fork that does not have a life.....
    The WHite lift strut in the photo below is a later model Kitfox strut. Note the end of the strut is drilled and threaded to accept a MALE rod end....
    This is better but I think I will design some kind of secondary load path for th strut attach point.... Probably a flat strap that picks up on the lift strut wing fitting and then is riveted to the lift strut tube with 4 or 5 steel high shear cherry max rivets. 
    WHen new and tested even the cut threads will hold a lot, but they are WAY more suspetable to fatique crack(the cut thread already has a built in stress riser), add to that flight cycles, people pushing on the struts and you are asking for trouble....
    The way Avid and early kit fox struts were built is the way to to go. Put the attach bolt in shear. The CAA accident aircraft C-FOLD  (theres a good N number!!!) shows a threaded strut end fitting that failed and they think it failed on take off. WHo know the history.. was it in a previous accident? How old is it? Was it rusted? Anyway according to he accident report the aircraft lifted off and a loud crack was heard followed by an uncommanded roll to the left...... it was the left rear lift strut attack threaded part that failed.... The plane crashed and was BER...
     
    dft_avsafety_pdf_023415.pdf


    • 0
  8. zadwit added a post in a topic Another Flapperon Failure   

  9. zadwit added a post in a topic Another Flapperon Failure   

    from another thread about thread failure:
     
    I will say that AVIDs do have what seem to me to be a stronger wing attach fitting by eliminating the rod end. Kitfox used rod ends I think to compensate for variances in build tolerances but I don't think it anything to worry about. I would check with John McBean to find out the exact procedure of what you are asking. You only need one thread to fail ,so no matter how far it screwed in the rod end the one that will fail will be out side of it . Does anyone know the actual shear strength of the threaded part of the wing strut attach point ? I would bet each of the 4 attach points are 4000 to 6000 pound tensile and we fly at 1200 or so lbs divided by 4 = 300 each ? MAke sense ? If I am correct that means at 10 gs you are pulling 3000 pound force and I guarantee you that you won't see 10gs. I am done talking outta my ass now. > I would think a connection that important, and under that much stress would have all the bolts in sheer, not tension. If those 8 or ten threads fail, your cooked. > > -------- Rotax Dealer, Ontario Canada Flying Videos and Kitfox Info http://www.cfisher.com/ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=140724#140724 ________________________________________________________________________________ From:"fox5flyer" <fox5flyer(at)idealwifi.net>Subject:Attachment fitting at top of lift struts.Date:Oct 19, 2007One thing that needs to be remembered is that AN fittings have "rolled" threads, not cut threads. This makes them much stronger than the normal non-AN threaded fitting and much less susceptible to stress cracking at the threads. Personally, if there was anything to worry about I believe it would be the fittings at the horizontal stab where there is a history of breakage in the IV. For what it's worth. Deke S5, NE Michigan ________________________________________________________________________________
    Subject:Re: Attachment fitting at top of lift struts.From:"dave" <dave(at)cfisher.com>Date:Oct 19, 2007> I believe it > would be the fittings at the horizontal stab where there is a history of > breakage in the IV. > I think that perhaps the breakages was due to rough ground handling using the horiz.stab braces for handle rather than using the Fuselage handle. Would this be the likely culprit ? He have rolled thread on the strut atttach point? SO what is the tensile of them and the rod ends ? -------- Rotax Dealer, Ontario Canada Flying Videos and Kitfox Info http://www.cfisher.com/ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=140728#140728 ________________________________________________________________________________
    From:"Ken Harrison" <kenharrison(at)comporium.net>Subject:Re: Attachment fitting at top of lift struts.Date:Oct 19, 2007OK, that makes sense. Except I wonder if one of the lurking engineers on the list could calculate the in-flight load on one of those fittings. Because I think you have to account for the fact that the strut is not attached to the wing at 90 degrees. The in-flight vertical load per fitting is 300 pounds, but the strut is at about 60 degrees from vertical (or more, I didn't actually measure it). Just for example, if the strut were at 45 degrees to the vertical, and had a 300 pound vertical load from the wing, the tension felt by the strut would be 600 pounds, and 600 pounds of compression felt by the inboard wing spar. (Now I'm showing my ignorance.) Is that how it would work? The same as the vertical and horizontal components of lift felt by a wing in turning flight? Anyway, I think I'm just worrying for no reason. It sounds like the connection is plenty strong. I'll go back to worrying about ground-looping. Thanks for the info. -----Original Message----- From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of dave Sent: Friday, October 19, 2007 5:51 AM Subject: Kitfox-List: Re: Attachment fitting at top of lift struts. Ken, I think you will find that there to my knowledge has ever been a inflight breakup of a Kitfox from the wing strut attach fitting. I think the testing showed in excess of +14G and still no failure. But I stand to be corrected. I will say that AVIDs do have what seem to me to be a stronger wing attach fitting by eliminating the rod end. Kitfox used rod ends I think to compensate for variances in build tolerances but I don't think it anything to worry about. I would check with John McBean to find out the exact procedure of what you are asking. You only need one thread to fail ,so no matter how far it screwed in the rod end the one that will fail will be out side of it . Does anyone know the actual shear strength of the threaded part of the wing strut attach point ? I would bet each of the 4 attach points are 4000 to 6000 pound tensile and we fly at 1200 or so lbs divided by 4 = 300 each ? MAke sense ? If I am correct that means at 10 gs you are pulling 3000 pound force and I guarantee you that you won't see 10gs. I am done talking outta my ass now. > I would think a connection that important, and under that much stress would have all the bolts in sheer, not tension. If those 8 or ten threads fail, your cooked. > > -------- Rotax Dealer, Ontario Canada Flying Videos and Kitfox Info http://www.cfisher.com/ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=140724#140724
    • 0
  10. zadwit added a post in a topic Another Flapperon Failure   

    IF you Google "spherical rod end failure" you will get a few hits and if you look at them, you will se most fail right where the jam hut is... Any thread under tension is a bad deal and in this case it is a  single load path or what I like to call a "single point of failure" which could result in loss of the aircraft.  I never liked the threaded rod ends on the end of the lift struts on Model 4 kitfox. They are not very big and a few have failed with the plane going into a uncontrollable spiral.... IF a kitfox has a GW of 1500 # and it has those little rod ends, then look at a  Cessna 120 or 140. It has a gross weight of 1650 and he HUGH rod ends on the end of the lift struts....3/4" diameter or larger threaded rod ends...
    PUt the threads under tension, install a jam nut to increase the tension, add in rust pits and more than likely you will exceed the damage tolerance of the part and it will fail.
    IN the case of the flaperon rod end, it was probably binding somehow and eventually failed.
    • 1
  11. zadwit added a post in a topic Another Flapperon Failure   

    I have seen 3 of these spherical rod ends fail in the past 10 yrs.  one was on a cessna 150 the other on a Cessna 172. Both failures were on the push pull rod that go from the rudder pedals to the steering collar in the nose wheel. When one rod end fail, the nose hear turns sideways and digs in flipping the cessna 150 and in the case of the 172, running it into a ditch. In both case both planes were totaled. The 3rd failure was a threaded rod end on a PA-31 Navjaho nose gear up lock cylinder. IN this case the rod end had a few tiny rust pits right next to the jam nut. So small rust pit= stress riser and the jam nut put the threads under tension and eventually it failed.
    ON the Cessna 150 and Cessna 172 no indication of previous damage or rust, however both failed right where the nut puts the threads under tension.
    If a person could look at the rod end that failed, on the Avid, look to see if it was a brittle fracture(frosted appearance on the fracture surface) or if it was ductile overload which would leave tell tale signs of 45 degree shear lip. 
    At any rate, Id inspect rod ends on flying aircraft and clean with MEK , NO wire brushes, and inspect as closely as possible with a 10X glass. Any sign of rust or imperfection, dispose of the rod end and get a new one. ONe other possible thing to do is make a flat plate with holes on each end that lays over the rod ends as a fail safe prevent. THe flat plate would have to be slotted a little bit.
    Other items to look for are make sure the threads are rolled  and NOT cut threads. Make sure the rod end is free to rotate and not binding. Also look and see what happens to the geometry of the rod end if the flaperons are extended more than 23 degrees.....it might be possible to cause binding by exceeding the flap down setting.
    Just my ideas.....
    • 1
  12. zadwit added a post in a topic home brewed nav lights   

    the white LED light I bought at Autozone store. The paper with them say "truck Tuff" truck light bars, white....not much there... Ebay has them from China for a couple of dollars!!
    They are about 4" long, 3/8" wide and deep and very bright.....
    • 0
  13. zadwit added a post in a topic home brewed nav lights   

    Here are a couple I found on the internet.... there are lots of them out there ....
    LED lights.webp

    • 0
  14. zadwit added a post in a topic home brewed nav lights   

    I bought them several years ago off Ebay so dont have any of that info... There are others on Ebay however.... they are typically used on boats for port and starboard ID... and they seem to be plenty bright.....
    • 0
  15. zadwit added a topic in Avidfoxflyers General Hangar   

    home brewed nav lights
    I installed LED lights on the wing tips. They are for a boat and cost $24. Also I install two small strip LED light that I got at Autozone for $8. They are pretty bright....IF I had $500 I guess Id buy wingtip strobes.. but alas I am but a poor homebuilder especially with the stock market down turn...!
    Here are some photos... Wingtip LED nav lights, Garmin G-5 in panel tied to Garmin Area 660.  Also photos of my muffler can with shourd and tin foil to insulate it  runs hot air to cabin heat box by my feet. I would have preferrd to mount the heat box someplace else but no room...
    Id instal a water heater but I cant see how to force the water thru the heater.. I had a water heater in last 582 kitfox and it was barely warm. The water just ran to the radiator and thru it back to engine... Maybe the aluminum radiators have low resistance and so the water would flow thru the radiator easier then thru the Tee to the water heater in the cabin.... I might work onit later....
     
    • 0 replies
    • 49 views