akflyer

yes sir, pretty common problem. I had to replace all mine. You can get the replacement rib tails from Airdale pretty darn cheap. It is pretty easy to replace them, pretty much the way you are thinking about it. peel the cap strips back, slip the new rib tails in, clamp them in place and glue.

and a few shots of the various stages of the re-build.

The red lines indicate the welds on the two sections of the upper longerons that were bent when the previous owner put her on her back.

Looking good Randy! I think alot of the build time gets lost when the destructions are not very clear and alot of time is spent scratching your head trying to figure out what goes where and how. Keep plugging along and she will be in the air in no time!

Well it was on floats, the II did not have a ventral fin, and the III did, so it was hard to tell how much was due to the fin, and how much may have been the increased vert. stab. Flying wise, I really did not notice much difference in overall handling. TO and cruise was about the same, with the edge going to the II due to the IFA and being able to get max RPM on take off. Same with the cruise.. It is just hard to beat being able to dial that pitch from the cockpit, I mean, from under the hood while on the ground wink wink

4 Strokes have their own issues... So what you gonna put in the nose of the fat bastard? I know the feeling.. Just cause you think it is OK now does not mean it cant be better right? One of my race buddies thinks that to get the most out of his sled, he has to lean out the main jet till she burns up, then go one size fatter He does not listen to us about plug reading etc, or look at what we are running, he would rather burn down on a practice lap, then work like a mad man putting on new jugs and pistons before the race.. I think he just likes to show off how quick he can swap jugs

<to the guy behind our planes

Would be way cool if we could get him out of the work shop every once in awhile and pop in here to put in his .02 on some of the technical issues or questions we had for him. Who better to answer any of the big questions than the guy who designed the plane

When the Avid first came out it was powered by the Cyuna 430 engine. It made a better boat anchor than an engine. With the switch to rotax, they became much more reliable. Kitfox did not come out till the Rotax was the engine of choice so they did not get in on the first round of engine failures. The writer could have put that little tidbit of info in the article and it would have shed a different light on the comparison, however, a good journalist who actually does some research and gives all the facts is pretty hard to find these days..

well just to quantify, I have flown the KF I, II and III with 582's in the nose.. On the III it had a warp and I did not monkey with it, but I have quite a bit on the II. There is no real difference in flying the III and the II so I tossed out what I had learned.

Let me know if you need it. It is never funny when your watching someone struggle to get the engine running right... Unless you are one of those guys that refuses to take advice from others who have gone before you. Then we get to as you end up doing what was suggested after you do a complete rebuild, buy new carbs, and shake the airframe and gear box apart trying to monkey with it before actually doing what was suggested

I have a C box, AK Bob has a C box. My other buddy had a B box. I have run the GSC on both B and C boxes and compared IVO Versus GSC on bot types of boxes, in ratios of 2.58, 2.62 and 3:1. I still like the 3:1 and IVO combo better than the GCS.

Doug, PM me your addy if you want and I can have my kid send out my electronic carb syncro if you want to try that out. Just pull your primer lines off and put the vacuum lines on those ports.. It is the Carb mate one that Calif. Power sells (among many other places I spose).

Yep, Idle jet.. Running rich leads to more issues than plugs.. Set the prop so you can turn 6500 on take off or you are leaving alot of performance on the table, and you are working that engine a good bit more than you really need to. It is harder on it to lug it down, that to let it rev to where she makes the most power.

We (I) took off the 68" GSC 3 blade and put an IVO 68" 3 blade ground adjust on it.. It was a noticeable difference in performance and the IVO wins hands down! Take off, climb and cruise all went up, and she idled much smoother. I am going to guess due to less rotating mass on the "B" box.

Do you have a B or C box? Sounds to me like your too rich on the idle. On the ones with out a clutch, I have set the idle at 2-2200 to keep it smooth. mine I can idle down to 1650, but I have a clutch. On my buds Mk IV it would shake like a bitch when cold and you would get gear box chatter under 2500 or so, but once warmed up a little, she would smooth right out and you could go to 2000 no problem. do you have mixture enricheners? it is possible that they are not closing all the way and you are getting rich on the low end, OR your air screws are not set right. Turn them out about 1/8 turn each and see what she does.

We ran the 68" and 72" IVO 3 blade. I tried the 2 blade (72") and thought it SUCKED. Both of these I ran ground adjust and IFA. I have no idea what the pitch was on the GA as I just tweeked it on wheels to get static RPM of 6200 which gave me right around 6450 to 6500 on take off. On my buddies Mk IV with 582 and same gear box you have we took off a GSC and put on the GA 68" and it really woke the plane up. Take off, climb and cruise were much better! I have been running the 72" since I got my plane in the air and would not go any smaller for the things I do (get in and out short).

I would put the prop switch in the cockpit and put a fake one under the cowling.. you think during a ramp check they are gonna be looking for prop controls? just tell them it is ground adjust and the motor is burned out so you cant adjust it at all right now. They dont need to see it functioning during a ramp check...

I was just at the guys place that is machining the adapter plate for me. He just completed his cub rebuild project after a little uhoh, and he is ready to get started on it. I was going to go with 2024 as suggested by a guy that has a done several conversion of engines to adapt the Rotax gear box to them.. My machinist buddy said I was stupid if I used anything other than a 70 series especially on floats for it better corrosion resistance and strength... so off to order the new aluminum today! Time for me to stop the summer time playing activities the few short days I am home and get back on this conversion!

Doug,

I went back and forth between 2.62 and 3:1 with my IVO IFA and ground adjust. I much perfer the IFA and 3:1. I know IVO says it is not recommended to use 3:1 with the ultralight prop, but in 180+ hrs I have not had an issue. I check Tq on the bolts and the SS tape between the bladed, and I have not lost any TQ on the bolts nor had the SS tape cracked. Here is what sells me on the IFA. When the prop is set for best cruise (just yesterday I had it set up at 5950-6000 burning 5.1 GPH, EGTs 1150 and 83 MPH on floats). I landed on a huge lake and decided to try a take off with the prop set for cruise. I could only get 5100 RPM initially, and after a run of about 1500' I got it on top of the water and accelerating and was eventually able to get the rpm up to 5900 or so while on the water. As soon as I broke water (around 2500 to 3000') I was able to accelerate and get the RPM up to around 6450 in a 60 MPH climb. With the 2.62 the water performance was even worse!

I tired a ground adjust hub on floats one time... To get the take off RPM I had to flatten it way out, but as soon as I got in the air I had to pull the power WAY back to keep from over revving.. Since the engine then had damn near no load on it, the EGT's went through the roof. I had to pull the power way back, get the nose up, then fly a high alpha pattern hanging it on the prop to load the engine enough to keep the EGT's under 1200. I was not liking that one little bit!

With the IFA I flatten it out to 6500 as soon as I come in with the power and if I need a small bump on TO I can feed it in. I think this is where the constant speed module would really shine, and one of these days I will buy one!


On wheels I have run the 68" GSC, Warp, Brolga and IFA & Ground adjust IVO prop. All in 68" 3 blade and my new IVO is 72" 3 blade. The only prop that was close to the IFO in terms of pull and smoothness was the Brolga, but you cant get them anymore. If I could find some I would buy all I could find as they really are an animal and it makes AKFLYERBOB'S KF perform AWESOME!

SWEET, have you been putting some hours on the KF? This summer has been so crappy that I am lucky if I have 50 hrs in mine.. Normally I would be getting in 250-300 hrs just on floats in the summer.

The speed wing does not have the undercamber in the wing. If they built it to HH specs (more ribs and heavier spars) then you really have the best of both worlds. The full length speed wing will fly almost as slow as my HH wing. I could get my buddies MK IV with the extended speed wing in and out just as short as my C HH.
Wing contruction.pdf

I see something really disturbing here... the ole fat bastard looks like it has become a shelf for damn kitfox turtle deck... It is a sad sad day in fat bastard slackers history....



I know that some people took the left offset out on the rudder when they built them and shimmed the thrust into the engine depending on which engine they used.

I flew in one out to Johnston Atol... They are freekin HUGE inside. I think the Avid is small when I get out of the Beaver or Otter... I can only imagine how you feel after getting out of that bird and then going for an evening cruise in your Avid

Cripes that is a big ass bird! I miss seeing them fly by my window at eye level going into Hickam all day long. Damn things are so big it looked like they were hardly moving and were ready to drop out of the sky!

That's gonna leave a mark!

In every wreck I have been involved with, the tube and fabric planes fared much better than the spam cans. But I would probably attribute most of that to the fact that the tube and fabric planes were also flying much slower at the moment of impact.

I know that from what I have seen, the engine can go either way... Most time she will give you plenty of warning that it is not feeling well and you need to check it out. Say the seals start leaking.. you will notice one EGT start climbing as that cylinder leans out, or she starts loosing power and wont turn full RPM on take off for no good reason, check the compression and the rings and see if you have some carbon in there that are causing them to stick.

Then there are the sudden HOLY SHIT moments.. I had this happen to me when the rings failed on BOTH cylinders (sure am glad I had that 20 knot tailwind to make the airport). I was flying along fat dumb and happy, EGTs and water temps perfect, then suddenly... the loudest silence you can imagine.. Turns out that the pistons and rings that ole will wayne sells on ebay are junk. The rings railed on both my engine and AKFLYERBOB's engine (on his we were able to milk it around a very short pattern and get her back on the ground).

Say one of the hoses ruptured or came on on the RV oil bottle. I know from experience that when you run out of oil in that center cavity, you have about 15 minutes before the engine stops running, for no apparent reason... That one was a real head scratcher for me till I pulled the air filter and looked through the carbs while the kid hit the key..

At any rate, I still trust the engine to get me where I want to go and dont even think twice about it. I have had engine failures on Lycomings too so it is not just 2 strokes that give up the ghost on you!