zadwit

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
      
      
________________________________________________________________________________

One 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 ________________________________________________________________________________

> 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 ________________________________________________________________________________

OK, 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

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.

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.....

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.....

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

LED lights.webp

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.....

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....

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....

IN the 90s at fouts airfield in Fairbanks, Ted Rufli built an experimental supercub and put a Mazda rotary engine in it... He used a cherry bomb muffler..during gorund runs, the engine seized, but not one to give up Ted got another engine and isntalled it . Several local pilots flew it and they said it has plenty of power but was extremely loud and gobbled fuel..and the exhaust ran red hot... the muffler ran so hot the insides burned out...in short order. Ted installed a stainless cherry bomb muffle rand it did better but then one day it caught the belly fabric in fire....After that I built Ted a 180 lycoming engine and he installed that... That engine is still running today...!

I like the rotary engines... there was a guy in Anchorage who put one in an experiment Pacer but he had several engine failures. to Landed on the Seward highway one time. Each part that failed, he rebuilt out of steel and eventually got to where the engine was reliable....I agree, there is nothing out there that puts out the power for weight of the Rotax.. the rotax being 2 stroked has to be understood by the pilot or it is easy to burn it up....Also at 6000 rpm if something starts to fail, it goes pretty fast with not much warning...but if you have a good engine to start with and know how to operate it and have it jetted properly and the prop pitch set right to load the engine, you should be good for 300 hours or so... for most that is a few years flying....

In the late 70s in Fairbanks, Doug Fowler built a KR-1 only he modified it a lot. LOnger wing, GA-W-1 Airfoil, different canopy , A-65 continental engine. He made his own wood prop. IT worked pretty well. He made several more props, each one a Scimitar prop and the last one he made was pretty radical Scimitar prop. He gained 15 mph in cruise with the last prop he made. Now the dangers of Scimitar dates back to WWI, the trailing edge of the blades is under a lot of tension and can crack. Doug made his prop out of thin laminations of wood, spruce I think and then after the blades were shaped, applied 8 to 12 layers of .8oz. fibreglass cloth, each later squeezed out to remove excess resin. He could make the blades thinner by l adding the fibreglas cloth.

The last prop was 68" I think and was a radical scimitar shape. It has a fair amout of pitch but when the engine rpm increased, the blade twisted towards a flatter pitch due to centrifugal twisting moment and centrifugal force. In WWI some of the early props flutters and self destructed so the amount of sweep was limited. Anyway as Dougs plane increase in speed, the airload on the prop decrease and he could reduce RPM and the blade naturally twisted in a coarse pitch direction...pretty neat. ALso the sweep of the blade delayed onset of mach compressible airflow so the blade had less drag at higher RPMs. Photos of these props are shown so you can get the idea of how it works...

YOu could buy a cheap borescope at Harbor Freight tools and look in the cylinders for scuffing... Then do a compression check both cylinders.... Then with the plugs out, but connected to the wires, spin the engine and see if you have spark....what you are trying to do is eliminate things that cause engine failure... spark, compression, fuel,

Fuel delivery is always a suspect... partial blockage, unporting a tank or sucking air intothe system before the engine fuel pump.. (this is why I put and electric fuel pump  on my and use it on takeoff)

So in summary, compression, spark, fuel.... if you have all that, prop the fuselage up and secure it well and put any sort of prop, flat pitch and see if it will run.. you dont have to do a full power run just see if it will start and run....

ONe thing also to check( MAJOR ITEM) is hold the carb slide open and turn the engine and see if the rotary valve is rotating with the cranksshaft.. Mine shears the brass gear and quit cold....all else was good....IF the rotary vavle is not rotating, it will not run

Let us know what you find.....

Currently running a WD 3 blade 68" sq. tip, set 13 degree= 6250 RPM static at 30(f) 2500 MSL.

I figure the only time I will have too much heat is when Im on fire!!

I made a muffler heat shroud and NO ram air in, just cowling air, plenty of pressure there, and run the air outlet to a cabin heat box 2" aeroduct.

I used fibreglass wood stove door seal on the ends. I might make another small shroud for the down tube is I need more preheat for the main muffler...

I have the small water heater to install in cabin but if I can live without it, I prefer to do that....Enclosed are photos... I dont know how but move this post to the heater file if there is one...Mark

PS used aluminum foil tape on ends of shroud to keep warm air inside muffler shroud...hope it works... anyone ever wrap the outside of the muffler can to insulate it???

I installed aviasport EGT instrument from Aircraft Spruce... Spruce also has the "K" type thermocouples but kinda expensive. If you look on ebay they are pretty cheap so I ordered several . I put the system together on the benche and used a torch and a westach egt system as a test standard and they both read the same... .the aviasport is easier to read.

one instrument changes from front to rear cylinder every 2 secs so one guage for 2 cylinders....had good luck with it so far.

Also the instrument needle has an expanded scale so is easier to read...

Like I say, go to ebay and look for "K" type thermocouples.....pretty cheap

Vance is absolutely right on this egt probe placement.. I went thru the exact same problem.. mine were too far out and the holes drilled from the side.....once I got it set up properly, everything fell in place and the egts read normal now.....mine run about 1050-1100 depending on where the prop pitch is set.... the prop pitch will affect egts but yo9u need to know you acan trust the egts readings before making other changes.....

Sometime life gets in the way!   I had a lot more work to install the 582 than originally thought... Had to change mount, mount system, muffler, and then the cowling was 3" too long so had to cut the cowl in half and splice it back together.....that was a lot of work because I had to relocate most of the camloks....

The Aerolux is 72" diameter and it is a big prop for this set up... It really pulls and the plane if off the ground in 75 ft climbing....IT cruises a little slow, 85 at 6000 rpm so I think a

smaller diameter prop with more pitch would yield better cruise speed. one degree of pitch change, changes the RPM 300 RPM because the prop is so large....

I also installed a Garmin G-5 tied to a Garmin Aera 660. This way I can push the button and the HSI gives me heading to the waypoint. The G-5 EFIS seems to be very accurate when compared to the GPS and the Kitfox Airspeed.

The VGs seemed to make a pretty good difference. I was not sure at first but the more I fly it the more I realize they do work. They make the stall more docile.

I tried to get a video of me flying the other day but I failed to get the camera turned on. IT is clipped to the bill on my cap and I thought it was on but it was not.... Ill get some videos soon. Im looking at a couple of different heater options....cant have too much heat.....WHen I was living in Alaska I was always modifying aircraft heater systems to get more heat....

The colder it gets outside the more difficult it is to rob heat from the engine... from 0 on down it get a lot harder to get heat without covering over the engine and then you have to careful you dont climb into warm air aloft so whatever system a person uses, needs to be controllable from the cockpit even more so with these Rotax 2 strokes...

Mark

I finally got my new 582 installed with a 72" two blade Aerolux prop from Green SKy in Florida. THe prop is the smoothest prop I have flown yet, much smoother than ivo or warp drive. I suspect it has to do with the airfoil shape of the blade. Warp and Ivo both have flat blade faces which improve low speed thrust but I suspect at cruise they are turblent flow somewhat. The Aerolux has a blade with curves on both the face and back of the blade. Performance is about the same at IVO or Warp Drive. 5900 static,  climb 1100 fpm at 6200rpm, Cruise at 6000 rpm=85mph

The finish on the blade is superb. Setting the pitch is dead easy, dont need a protractor.

Ive been fighting my MATCO brakes for some time but I finally got them to work satisfactorily. I have dual calipers on the wheel end, the small master cylinder (MC-4) and 8:00x6 tires, all brand new. I could only see 220psi pressure at the slave cylinder(wheel). MATCO says I need 450psi,   I redrilled the rudder pedal and moved top of the master cylinder as close as I could to the pedal and now I have adequate brakes. I cant really raise the pedal or make it taller because I have a nose tank and there is the throttle connection right above the right rudder pedal...It is still a little hard to get my toes on the top of the pedal but I plan on installing non skid slip stuff on there...

I did several landing on pavement , wheel landing and full stall all in a 12 mph quartering cross wind and if the plane started to weathervane I stabbed a brake and it just stopped..There is probably room for improvement on the pedals but it would take a lot of redesign of the area above the rudder pedal and elimination of the nose tank...Ill enclose a photo of  the brake pedal before I drilled the attachment but you can see there is room to move the top of the master cylinder closer to the pedal...

I will probably end up cutting the back of the cowl to shorten it and then relocating the camloks that hold it to the fuselage....not looking forward to this  but Im pretty sure it will fix things. the top cowl has a lip to fit to the windshield so that might be a little harder to reproduce after I cut it to shorten it...

The factory list cowlings for about $1000 plus shipping . I might call them to day and ask if there are two different lenght of cowlings...

I think my cowl is longer from back to front than the 4 piece cowl, the one with the 2 cowl rings on the front.....

I measure 25-3/4" from front face of firewall where the motor mount bolts on to the front edge of the nose ring cowling

I measure 23" from front face of firewall where the motor mount bolts on to the front face of prop flange.

I have this kitfox Classic IV that came with a 503 Rotax. I removed it and am installing a 582 ROtax. WHen I went to install the cowling I noted the engine is so far aft that the prop will not clear the cowling. I added a 2-1/2" prop spacer and the prop barely clears the cowling. I am thinking I might have to get a different cowling at some point.... Any ideas?????

I point out where the old exhaust was and now you can see the engine is aft of where the cowling was cut to clear the old exhaust...

Mark

5606 is mineral base hydralic fluid,, DOT 5 is silicon based, not sure what it will do to the brake seals, probably swell them and make the brakes inop.

Regular car brake fluid is ester base and will definitely  swell the brake O rings.......YOu can do a google search or Ebay search for mil spec H-5606 and you will find lots of it,, 

ROyco makes it and it might have a different number but look in the fine print for  Mil-H-5606

The brake disc are nice and true and the running clearances between the brake pads and the disc is minimal so when I push on the brake pedal it does not seem to travel any farther

(if it does it is not noticable). IT does improve the braking action but still not enough to hold the plane above about 1/2 or 3/4 throttle....ITs better but still not right....or as it should be.

By having dual caliper, it increase the surface of the brake pads onto the disc. HOwever if I did it again, I would try the brake intensifiers, they are thin wall cylinders that fit inside the brake master cylinder and make the master cylinder piston smaller thus able to make more pressure...