whizzers

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Everything posted by whizzers



  1. whizzers added a post in a topic Bush gear failures   

    Update on the gear. One possible fix for existing gear. I had two yokes made similar to the yoke on a universal joint. They were made out of 1 1/4 cold rolled square stock. I threaded them 3/4-16 inside, and turned that end round to give 3/8 inch wall thickness. The fork end I milled out 7/8 inch wide to provide +1/8  wall thickness, and drilled that 1/4 inch.
    I then made new longer axles, but threaded the inboard end to give a tight fit on the thread. The fork was threaded on, then drilled and pinned. I had to make new lower spring strut rods since they are shorter than original. The only issue I had was that the axle end of the spring rod has to be canted a bit to fit to the existing cabane. That and the 3/4 inch tubing AirSpruce provided won't accept a 3/4 inch wheel bearing without polishing it first.
    The top (spring) end of the inner rod should be doubled internally to avoid the hole tearing out. I saw that happen on a Super Cub clone.
    I put the gear back on the plane, but have not tried it yet.
    The other possible fix is to weld tabs to the existing axle tubes. I will try that next.





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  2. whizzers added a post in a topic Wanted - 582 engine mount   

    https://www.ebay.com/itm/Avid-Model-B-Engine-Mount-Ultralight-Experimental-Rotax-Kitfox-Aircraft/253228472171?hash=item3af597d76b:g:Im4AAOSwbF1Z8qBd&vxp=mtr
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  3. whizzers added a post in a topic Wanted - 582 engine mount   

    there's one on EBAY
     
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  4. whizzers added a post in a topic Let's talk gear geometry   

    I am going to try to build a set of gear to the dimensions and angles used on the Piper Cub. Has anybody built gear where the front leg comes straight down from the fuselage instead of leaning forward 3 7/8 inch. This would put the mains a bit farther back. It would make the gear leg and the cabane easier to build.\
    It would make the tailwheel come up faster but what other effects might it have?
     
    Bob
     
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  5. whizzers added a post in a topic Bush gear failures   

    Yea, I think ideally scaling the gear using the Angles of the cub gear would be the best overall solution, but would involve building new gear all around. I'm thinking about milling a nut out of square stock with a fork on it to thread on the inboard end of the axle shaft. That would be relatively easy and inexpensive, and just might do the trick.
    Good to hear from an expert, thank you. Please stay in touch.
     
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  6. whizzers added a post in a topic Let's talk gear geometry   

    I finally got to do a little playing with the gear. I made a mock-up and ran some tests, and here is what I found, or think I found anyhow. I documented what I did, and since the file is long, instead of posting it here and taking up space, I have attached it as a .doc file. If you are interested, you can read it, if not, ignore it. I figure if you guys find anything wrong, you'll soon let me know.

    Bob Landing Gear Geometry.doc
    Landing Gear Geometry.doc
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  7. whizzers added a post in a topic Bush gear failures   

    I finally got some time to play with the gear issue. What I think I found is surprising, and pretty much confirmed my suspicions. I did document it, but the document is quite long, so I will post it here as a .doc file. I figure if you want to read it, go ahead, if not, ignore it. I also put it here because I figure if there are any flaws in my logic, you guys will find them. Landing Gear Geometry.doc
    Landing Gear Geometry.doc
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  8. whizzers added a topic in Avidfoxflyers General Hangar   

    Bush gear failures
    I have had several landing gear failures since going to the spring "bush gear". I have been researching the subject and have noted quite a few similar failures of that type gear, all in about the same location and of the same nature, Inward bending of the forward strut leg. I have been reluctant to re enforce that leg for fear of promoting a more serious failure elsewhere. The gear is a Chinese copy of the gear used by Piper from the 1930s onward but the Piper gear does not seem to suffer the same failure. Today I made a cardboard model of the gear geometry and I believe I have located the problem. The bottom anchor bolt for the spring leg on the "bush gear" is fastened to a metal plate welded between the front leg and the axle. When the spring strut is fully extended and bottoms out, or the spring becomes coil bound, that point then becomes a rigid fulcrum with the axle as a lever. The upward motion or the axle is then translated into an inward rotary motion on the front gear leg. The failure always seems to occur at the point halfway between the axle and the fuselage, which makes sense. I have never bent a rear strut, nor the spring strut, always the front one.

    Looking at photographs and real life examples of Piper, Hatz, and Pietenpol gear shows that the anchor point on those gear is at the inboard end of the axle. My model shows a significant difference in the movement of the middle of the forward gear leg when the anchor point is moved to the end of the axle. As a matter of fact, the farther inboard the pivot is, the lesser the rotary movement at the front gear leg center.

    I have yet to figure a force analysis on the gear, but I think i am onto something. I'll post more as I find more.
    On a positive note, my welding is getting better.

    Bob McCaa
    • 67 replies
    • 12,845 views


  9. whizzers added a topic in For Sale and wanted, you got it, I want it   

    Clean out the shop
    Trying to clean up the shop for more projects; Somebody needs these;
     
    Set of controls sticks and rudder pedals off "B" Avid set up for cable brakes,
    Set of control sticks and rudder pedals (hydraulic brakes) for a KF 1
    Set of lift struts for a KF I, also horiz stab, elevator, and rudder for KF i also set of tail "V" struts.
    Set of front mount radiators for Avid with brackets. Missing some grommets.
    Top section of KF I fuselage/ front and rear spar carry throughs.
    Gotta move this stuff guys or it's going to the yard.
    Bob McCaa seven one seven/ three six three/ seven five five two
    whizzers /at/ verizon /dot net
    Located in Central Pennsylvania
     
    • 1 reply
    • 747 views


  10. whizzers added a post in a topic Nearly a giveaway   

    Is this a Speedwing or a STOL wing? Interested in the airframe if it is a STOL or Heavy Hauler
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  11. whizzers added a post in a topic Fuel flow issue.   

    Thanks for the input. Have already done the fuel pump tests. The pumps are in series, with a by-pass check valve in parallel with the electric pump, which is a Facett. Fuel pressure with the Facett alone is about .3 Bar, and with the mechanical alone is about .4 Bar. (PSI= 14.7 x Bar) We did a free flow test after the work was done and with five gallons in each tank, it flowed about a half gallon per minute from either tank  through the header tank without the pumps running. The engine is a Rotax 912 80 HP and burns about five gallons per hour in climb, so we are more than adequate using either or both.
    My Avids are 582 gray heads, and I agree with C5engineer.
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  12. whizzers added a topic in Close Call's and dumb stunts   

    Fuel flow issue.
    My brother recently bought a KF Classic IV. While doing taxi tests, it ran for about an hour and a half, then quit. The EIS said Low Fuel Pressure. He loaded it on the trailer and took it home, where it promptly started and ran on the trailer with the wings folded back. He was unable to find any problems. About two weeks later, he was flying with an Instructor, and after about an hour and a hale, it quit in the air. Again "Low fuel Pressure". They tried a successful re- start. They made it down safely, and he loaded it and trailered it to my place for diagnosis. We talked to Lockwood, and Kitfox, and the best suggestion we could come up with was possible vapor lock. Unlikely in the air since it was cool that day. We began checking the fuel system end for end. Eventually we found the problem. The fuel line where it exited the wing and entered the fuselage had been fastened to the carry through inside the fuselage. This caused the lines to kink in the wing root when the wings were folded forward. When the tanks were full there was enough head pressure to keep the header tank full. When the head pressure went down, the kink prevented adequate fuel flow. What threw us a curve was there is a low level sensor in the header tank that never came on. Turns out it was defective. The "test" button on the instrument panel only tests the indicator light, not the unit.
    We replaced the hoses with AEROQUIP steel braided hose, and put a new sensor in the header tank . Added two items to the preflight and run up to: 1. run the electric fuel pump without starting the engine and check the pressure to confirm it works, and 2. Run the engine with the wing tanks shut off to confirm the low level sensor in the header tank is working.
     
    Bob McCaa
     
     
    • 29 replies
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  13. whizzers added a post in a topic speed wings/stol wings.   

    The speedwing does not want to get off the ground. I believe it would run the length of our 5000 foot paved runway with the tail in the air and never lift off. With the flaps at 10 degrees and the tailwheel hard on the ground it will "pop" off the ground and then climbs like a rocket. On approach at less than about 60 per it will come down at about 750 fpm. It stalls suddenly and without warning except that it begins a flat  turn to the right. In its defense, it doesn't bounce. When it's on the ground it stays there.
    I am skeptical that it would lift two people.
    I talked to Snaps down in North Carolina and he basically said "that's the way they are".
    Before you ask, it has been measured, weighed rigged, re- rigged, and compared dimensionally with other Avids at least fifty times. I have not tried VG's yet.
    I had a STOL wing that was a pleasure to fly. It wanted to float.
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  14. whizzers added a post in a topic speed wings/stol wings.   

    Couple of questions: Where could I get a drawing or pattern of the Riblett Airfoil?
    Second: My brother has a Kitfox Classic Four with a flat bottomed airfoil. It is six inches longer in the fuselage, and about 26 inches longer in span than my avids are. It also has a significantly larger fin and rudder.  I also had at one time a KF IV fuselage that I was going to put Avid wings on, but gave up on that project. I have done extensive measurements on the geometry of the carry- throughs on the Avids and the KF IV and; on the Avids the front spar carry through is 1 1/8 inch lower than the rear spar carry through, but on the KF IV  they are in line. This would have the effect of raising the leading edge on the Fox. by 1 1/8 inch. How would that play into the Riblett airfoil? Also how can I reduce the wash-out without de-glassing the tanks" Other pilots have told me that the Speedwing appears to be flying nose- high when it is in level flight. This would make a certain amount of sense if the necessary Angle of Attack of the flat bottomed speedwing is higher than the AOA of the STOL wing. It also makes sense if the KF uses a flat bottomed airfoil on the Classic IV.
    My brothers Fox has a flatter bottomed airfoil, and the ailerons are much closer to the wing than are the Avids.
    I am flying an Avid Speedwing, and an Avid Heavy Hauler wing with a KF front end on it, and I don't like either one. The performance of neither is very good, and the forward visibility out of the KF on the ground sucks. I am building a third one out of parts I collected, but it doesn't appear that the finished product is going to be any different than what I already have, and so I am not very enthusiastic about it.
     
    Bob
     
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  15. whizzers added a topic in Avidfoxflyers General Hangar   

    speed wings/stol wings.
    I have an Avid speedwing with a 582 on it, and I do not like the way it handles/ It "pops" off the ground and although it doesn't fly bad, it stalls suddenly and without much warning.
    I have a second set of speedwings that need some work. Do I want to: (1.) extend the Speedwing to full length or: ( 2)  Extend the spars and replace the speedwing ribs with STOL wing ribs. I have to make ribs anyhow, and it is just as easy to make a dozen as it is to make six.)
    • 19 replies
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  16. whizzers added a post in a topic Lift strut repair   

    Yea, the fitting is AN490-HT11P  Question was: I did not know if the fitting was rosette welded in two places, one of which was under the cross brace. Had it been a straight piece of tubing I'd have put it in the lathe and machined it out, but to try that by hand on something as thin as .035 tubing and risk going off center and then trying to drill and weld through an old weld didn't appeal to me. I could have used a 3/8 male threaded rod end into the plug, and bushed the bearing end down I guess. Might try that if it will fit the wing attach point. . That would make the bushing a bit less than .125 wall thickness, but that is not where the concern is. The concern would be where the old stub is welded in. As it stands, that wall thickness is .089 at the peak of the threads.
     




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  17. whizzers added a topic in Technical tasks   

    Lift strut repair
    I found a significant crack in the 5/16 thread on the top of my one lift strut. The end consists of a AN490HT 11P rod end welded around the periphery and rosette welded into a 3/4 inch x .035 tube. I doubt that I could remove the old fitting without wrecking the strut. So I carefully cut off the old threads and filed the end flat. I center drilled the end and slowly drilled it out 1/64 at a time until I came to solid metal. Turns out the I.D. of the AN490 fitting is 1/2 inch. I threaded it 9/16 National Fine, and was able to get a little over 1 inch of thread. I then made a threaded bushing 1 inch long x 9/16 o.d. with a 5/16 inside thread. Into this I inserted a 5/16 x 2 inch stud. I loc-tited the whole thing in place.
    Even a grade 2 5/16 bolt has a minimum tensile strength of 3900 pounds , and I used grade 5 at 6300 minimum. The O.D. of the AN490 is .679, giving a wall thickness of .089 at the peak of the inside threads. Maybe not the best fix but certainly the easiest.
    Give anybody heartburn?
    Bob McCaa
     
    • 5 replies
    • 922 views


  18. whizzers added a post in a topic AVGAS Vs: MOGAS   

    Right now more worried about the fiberglass tanks. I have no way of knowing which resin was used, and what the effects of the ethanol would be. There are a lot of postings here, but not consistently pro or con.
    I have one plane I put spun poly inserts in the existing tanks, and I wish I had not. It was a lot of work, and the internal crossfeeds are Mickey Mouse. I don't think you can get them any more anyhow.
     
    I have two choices here...10% ethanol, which is bad on the tanks, or AVGAS, which is not good for the engine.
     
    Bob
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  19. whizzers added a post in a topic AVGAS Vs: MOGAS   

    Gages are analog. The temp is not over, just higher than it normally runs. I drained the MOGAS out of the tanks and replaced it with AVGAS. Looks like maybe Tuesday I'll be able to check and see what effect it has.
    The monetary savings are about 30%, but not worth wrecking an engine over.
    N532SE;N533SE;N5113H Flying. Plus one undergoing rebuild, and another awaiting rebuild.
    All three have heavy duty belly radiators.
    Bob
     
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  20. whizzers added a topic in Avidfoxflyers General Hangar   

    AVGAS Vs: MOGAS

    I have several flying Avids with 582 grey head engines in them. I have been flying on AVGAS for the last several years with good results, as Ethanol Free gasoline  was not available here.
     
    Recently one of the local stations got ethanol free gas so I switched to try some.
     
    In both planes it raised both the exhaust gas temp and the coolant temp by 20 degrees, enough to cause concern. I could re-jet the carbs to lower the temps, but then if I fly somewhere and have to use AVGAS, I would be in trouble again. Has anyone else had similar experience?

    • 8 replies
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  21. whizzers added a post in a topic Avid and Kitfox parts for sale   

    I have no idea. I was told the stuff was Kitfox, for sure they are not Avid. The torn-up fuselage I got with the stuff is Kitfox, maybe I or II. For sure not IV If somebody needs the strut, text or call me and I'll get dimensions. If not, I'll cut them up for the tubing. The stuff isn't doing me any good. It doesn't eat anything, but it does take up a lot of space. I also have a cabin top.
     
    Bob
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  22. whizzers added a topic in For Sale and wanted, you got it, I want it   

    Avid and Kitfox parts for sale

    I purchased a couple of parts stashes to get material to fix up my Avids.  I have culled through the parts and taken out what I need. I will pass the remainder of the stuff along to people who might need it. Here is a partial list, feel free to make reasonable offers.
    Parts are in Central Pennsylvania.
     
     
    *One complete Avid airframe,B model  speedwing. Flyable but no paperwork. Rebuilt and recovered about five years ago with Stits polyfiber and Polytone paint.
    *1 set Avid Speedwings with ailerons , need inspected and recovered . Fuel tanks both  Sides.
    *Kitfox engine mount, early type with aluminum bottom plate.
    *Kitfox engine mount, later type with side mounts. Side mounts included.
    *Kitfox cowling, early model, bottom bootcowl broken but repairable.
    *Bottom boot cowl off Kitfox 4 New, unused.
    *2 sets short landing gear, Avid Flyer tail dragger. (bungee gear)
    *1 set tall gear, Avid Flyer tail dragger (Bungee gear)
    *1 set main gear, Avid tricycle. I do not have the nose gear.
    *1 set of large wheels and tires for Kitfox or Avid, size 21x12.00-8 on aluminum wheels  with rotors and brakes Tires are unused.
    *Early Kitfox horizontal  stab, elevator, and rudder. Needs covered.
    *Set of early Kitfox lift struts, one bent.
    * Early Kitfox rudder pedals and control sticks, also the linkages and mixer.
    *Set of ribs for extending Avid  Speedwing. No tubing
     
    Bob McCaa; whizzersatverizon.net 717 363 seven five five two

    • 5 replies
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  23. whizzers added a post in a topic Happy Update   

    Hi Rob. Good to hear you are back in the air. The Avid brother Tom and I collected from you is undergoing overhaul. We finished the wings through tape today. They will go on one of my present flyers. The fuselage will be a while yet, but appears to be a reasonably easy fix.  Thanks and good luck.
     
    Bob McCaa
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  24. whizzers added a post in a topic Avid went Down in Florida   

    Sorry about your misfortune, Best to you, and get well soon
     
    Bob McCaa
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  25. whizzers added a topic in For Sale and wanted, you got it, I want it   

    Kitfox parts;
    I cleaned out a hangar to get an Avid, and I came up with a bunch of Kitfox stuff I don't need. I have a set of five ribs for a KFII, doors, turtle deck,, rudder, horiz stab, a set of engine mounts for a 582 with plate, an engine mount for a KF4 with a 582 and side mounts, a broken round cowl for a KFII that is repairable, a bottom boot cowl for a KF IV, and a set of controls and linkages for a KFII. I also have the front top half of a KFII fuselage from the firewall to the seat back.
    Somebody might need this for a winter project.
     
    Make me a  offer/ any or all.
     
    Bob McCaa
    Lewistown PA
    717 363 7552
    • 0 replies
    • 915 views