ChrisBolkan

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About ChrisBolkan

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  1. ChrisBolkan added a post in a topic bungee cord length   

    Here's a pretty good write up on bungees. I have used the same directions for trike and TW. Also a pic of the jig I made to stretch the bungee ends to wrap the safety wire to form the ends.
    Bungee installation Steve Winder's how to.doc


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  2. ChrisBolkan added a post in a topic Just joined the Fat Avid Club   

    I have some rough numbers for speed with the various configurations and tires.
    The Tricycle configuration with 22 inch pillow soft main tires and an 800X6 front tire was a 95-100 MPH with me and half gas or so. 
    In TW configuration with the same 22 inch pillow soft tires and a 280-250- 4 tailwheel tire cruise bumped up to a pretty consistent 105 MPH under the same conditions.
    When I put the 29 inch cartoon tires on the mains and bumped the TW up to a 4.10 - 3.50 - 4 tire speed dropped back to around 95 MPH.
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  3. ChrisBolkan added a post in a topic Rotax 582 hose replacement   

    Look the hoses over VERY closely. If they are still flexible and don't look or feel cracked, stiff, brittle or burned from exhaust, I would use as-is. 
    The 582 RV oil circuit uses a (I think) 10mm hose that has cloth braid on the outside. it is very light and flexible hose that I could not find locally. That is really the only hose I have ever bought specific to the 582 from Lockwood. For all water hoses I either bough pre-formed hoses and cut the portion out that fit the particular profile I needed or used hose on a roll for longer straight pieces. I got the water hose from local parts shops that would let me look through all of their hoses. 
    When I plumbed my 912, I bought the metric oil hose from Lockwood and did the same thing with auto hoses for the rest of the engine. The 912 was more complicated so I made a drawing of the hoses and wrote the gates part number that I cut each hose from I used in a particular location. Occasionally I got lucky and one hose with multiple bends could be cut and used in more than one location. If I ever need to replace the hoses I have references to the part numbers of the hoses I used for a particular spot.
    There are probably better ways to do it but this is what I have done.
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  4. ChrisBolkan added a post in a topic The cliffs at Etretat   

    Beautiful photo!
     
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  5. ChrisBolkan added a post in a topic SkyRaider project on deck   

    Nice build!
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  6. ChrisBolkan added a post in a topic looking for avid mark IV condition inspection checklist   

    The Avid condition inspection checklists I have seen are pretty simplistic. I have found the Kitfox checklist(s) to be much more comprehensive. Grab one online and look it over. You might have to search around a bit but they're out there. Not everything in the KF checklist will apply. you should be able to go through it before you look at the plane and determine this things and just mark N/A or cross them out. This will give you a good comprehensive list.
    On the other hand, since you are doing with an A&P, Maybe you want to use as brief a list as possible :-) depending on your objective for the inspection.
    As far as the engine is concerned, Rotax has a table of inspection points for the 582 based on time ....every flight, 25 hours, 50 hours and so forth. Wouldn't hurt to grab one of those on line and print it out too. You can use whatever schedule on the chart seems appropriate for the inspection. It will certainly help you not to miss things..
    You will like the Avid. 
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  7. ChrisBolkan added a post in a topic In search of a Bellcrank and controls to fit a Magnum   

    The magnum bell crank and mixer system is well thought out. I think you may be able to use parts you have, but find someone with a magnum, go look at it and take a ton of pictures so you know exactly what you are shooting for. I think it will help a lot.
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  8. ChrisBolkan added a post in a topic In search of a Bellcrank and controls to fit a Magnum   

    OK, I get it. I assumed you were working from a kit and could not understand how the parts that would not fit. I thought it might just be misunderstanding of how things fit together. I owned a magnum and spent a lot of time working on it and am very familiar with them so I thought I might be able to help.
    Clearly those are not the right parts, and you are not building from an unfinished kit.  I understand now. Unfortunately I do not know where there are any parts you need :-(
    Chris
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  9. ChrisBolkan added a post in a topic In search of a Bellcrank and controls to fit a Magnum   

    Curious why you think it is the wrong mixer, or maybe how did you end up with the wrong mixer? Do you have any pictures to post that show the wrong parts and why they don't line up?
     
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  10. ChrisBolkan added a post in a topic Just joined the Fat Avid Club   

    I am aware of only two ways to prevent shimmy.
    1) A tailwheel that is light enough relative to the mass and stiffness of the spring and fuselage, that the natural resonant frequency of the system is too high to get excited and break into oscillation.
    2) A tailwheel that is heavy enough relative to the mass and stiffness of the spring and fuselage, that the system WILL get excited and break into oscillation, in which case the ONLY absolute cure is to critically dampen the oscillation with resistive damping / friction. 
    Caster angle is one component to help reduce the tendency of shimmy to develop and will help in borderline situations. A negative caster angle (bottom of kingpin behind top) will promote shimmy and a positive angle top behind bottom of kingpin will tend to stabilize shimmy. 
    However when you get a massive tail wheel in comparison to the mass and stiffness of the airframe, and DO NOT have enough resistive damping/ friction in the back and forth movement of the tailwheel to critically dampen the system, no amount of caster angle will prevent shimmy once it gets excited, or you will need so much caster angle that the tailwheel will not want to steer. 
    Resistive damping is the only guaranteed solution. I am 100% convinced of that. If you put a massive enough tailwheel on your plane WITHOUT resistive damping, it WILL shimmy no matter what you do, other than apply adequate resistive damping. 
    My tailwheel in the photos has positive caster angle by several degrees. For some reason the photos make it look negative. Here is a better picture. And thanks for pointing this out. I received similar feedback on the Facebook forum. It must be the fisheye effect of my iPhone or the angle I took the pics from 

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  11. ChrisBolkan added a post in a topic Just joined the Fat Avid Club   

    I've been having a ton of fun with my TW conversion. However, I've encountered the same TW shimmy with my Bearhawk TW assembly that I had on the Magnum. It took me a long time to come to the realization that really the ONLY thing that will absolutely eliminate TW shimmy is the proper amount of friction or resistive damping in the back and forth movement of the TW. Most tailwheel assemblies have some provision for adjusting the amount of friction and it ends up being a delicate balance of enough friction to eliminate shimmy while not having too much friction to prevent the chains and springs from being able to steer the plane on the ground. When tailwheels get big and heavy enough, so much damping is required that the tailwheel can no longer be steered with chains and springs attached to the rudder.
    The Bearhawk TW is an ingenious, relatively lightweight and simple tailwheel assembly, but its fatal flaw is that it has no provision for resistive damping, which is why I could never kill shimmy. I experimented with smaller and bigger tires, tire profiles, kingpin caster angle and so forth until I came to the realization that the ONLY cure was friction. Since the TW was never going to work as it was, I decided to modify it. I threaded the kingpin, removed the steering and release mechanism, and installed 2 belleville washers and a castle nut to allow the introduction of friction into the system. The new setup has no steering chains and springs. It is full castering and is steered by differential braking at low speeds and by air across the rudder at higher speeds or with blasts of power sending wind across the rudder at low speeds. It works great! It's different, but not better or worse than chains and springs and ALL shimmy is gone! I couldn't be happier.
    Another thing I am trying is a light weight tailwheel rim and tire. So far it is working great on everything I have landed on, but I have not really hammered it with big rocks or anything extreme. the weight of this wheel and tire is half the weight of the 10 X 3.5 X 4 Aero Classic tire and 3 piece cast aluminum wheel  you see used on big Cessnas and so forth. It's a reinforced nylon wheel made by Azusa and a Cheng Shin 4.10 X 3.50-4 4 ply Go Kart tire. This wheel and tire are so light weight, that much less friction is required to kill shimmy, so it might be possible to use steering chains and springs with it on a tail wheel assembly that has a provision for friction adjustment. This light weigh tire and wheel will significantly improve my baggage capacity too. An added bonus. 
    Hopefully it is strong enough and holds up over time. here are a couple pics.




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  12. ChrisBolkan added a post in a topic Avid flyer on Facebook marketplace Oklahoma.   

    Good eyes! I didn't notice it. So....is it broken or wood rotted? Seems odd that an inside one would break like that. Also, obviously not flyable even tho seller claims it is.. Seller said Cowl needed some work. I'd worry a LOT more about the flapperon hangar! 
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  13. ChrisBolkan added a post in a topic Stock Avid landing gear   

    Both my nose forks are gone. Sorry...
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  14. ChrisBolkan added a post in a topic This got the heart pumping a bit faster   

    You are lucky there is no damage. Something similar has happened a number of times to me when a passenger gets out. Fortunately in my case it has always started banging during taxi and I have been able to correct it before taking off. Fortunately other than being scary and the potential to produce cosmetic damage, there is no real danger. 
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  15. ChrisBolkan added a post in a topic Just joined the Fat Avid Club   

    Thanks! I will look at the geometry for that. I did have to lengthen the existing "adaptors" that screw on to the top of the cylinder and attach to the pedal. I could not get the brakes to activate very well with full rudder deflection. I will definitely look to see if it is possible for the brake to over center as you describe with my setup.
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