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Thread: Need advice on new landing gear please

  1. #41
    Crash, Jr.'s Avatar
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    Just the fittings are stronger. Airframes uses solid steel billet machined plug ends on the gear tops and the end of the axle where the shock strut attaches, round welds and rosette welds those in then puts a strap over them. It's probably overkill but that's the way it's done. Atlee just uses the normal fold the top of the tube together and weld a bushing in technique and I think they have a strap over the top too.

  2. #42

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    I can't resist. I have 3" Airframes Super Duty gear w/ 35s and I love it. Fit and finish is top notch. I love the Super Duty mid step and if buying more would prefer a fuel step on both sides and I'd lose the long step. But... 3" extended wasn't enough. I spoke with Crash Jr and favored Airframes 6" gear for the excellent quality but decided to use TK-1 6" gear because it's taller and Tony provides a taller cabane vee so suspension geometry is better. I'll have installed this weekend. If I was a certificated guy I'd use Airframes. Acme's the new guy and may be cool but they need to prove up. In the Exp arena? TK-1 rocks. 3", 6", and 8" extended with either standard stance or 3" forward. Here's a pic of my nephew's SQ2 next to my Rev on the day we switched his plane to TK-1 6" gear. Look at the difference in space between top of tire and bottom of airframe. If you have slats or horsepower to utilize it? AOA matters.
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  3. #43

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    Stewart- how are the tops of your TK1 legs constructed? The set I installed a few months ago had billet end fittings plugged into the ends as previously described, but no straps over the top or rosettes that I could see, just the perimeter weld. Tony is a smart guy and I’m sure he’s run the numbers and it’s probably fine, but it just caught my attention because all other brands I’ve seen had a strap over the top...

  4. #44
    Steve Pierce's Avatar
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    Quote Originally Posted by Crash, Jr. View Post
    Just the fittings are stronger. Airframes uses solid steel billet machined plug ends on the gear tops and the end of the axle where the shock strut attaches, round welds and rosette welds those in then puts a strap over them. It's probably overkill but that's the way it's done. Atlee just uses the normal fold the top of the tube together and weld a bushing in technique and I think they have a strap over the top too.
    Do you have some test data that the solid plug gear is stronger? How long has it been used?

    My understanding was it was done to save build time. I have not picked up a wreck where the fitting of the gear broke, usually the tubing folded somewhere and not a result of weak gear but usually terrain, pilot error or corrosion.
    Steve Pierce

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  5. #45

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    Quote Originally Posted by ak49flyer View Post
    Stewart- how are the tops of your TK1 legs constructed? The set I installed a few months ago had billet end fittings plugged into the ends as previously described, but no straps over the top or rosettes that I could see, just the perimeter weld. Tony is a smart guy and Iím sure heís run the numbers and itís probably fine, but it just caught my attention because all other brands Iíve seen had a strap over the top...
    The tops are as you describe. I never gave it any thought because I've never seen or heard of a gear fail there. The feature most of recognize with HD gear is the gussets at the bottom of the tubes. I think the way TK welds up the lower end with the removable axle may be stronger, but time will tell. I see Acme is doing a removable axle, too. At first sight I wasn't a fan of bolting an axle in but here I am installing it. I'm pretty sure they're all strong enough for 99.9% of ops I'll do so for me it boiled down to the height.
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  6. #46
    Crash, Jr.'s Avatar
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    Quote Originally Posted by Steve Pierce View Post
    Do you have some test data that the solid plug gear is stronger? How long has it been used?

    My understanding was it was done to save build time. I have not picked up a wreck where the fitting of the gear broke, usually the tubing folded somewhere and not a result of weak gear but usually terrain, pilot error or corrosion.
    I can assure you that milling major pieces out of a block of steel then welding them in place and welding a strap over top is far more time consuming that beating the end of a tube together and seam welding it.

    There's a couple reasons for the steel plug method, the first is accuracy. When building the way other manufacturers do you have to cut the tube overly long then fold the top together. This is largely done by eye and the resulting tube can be slightly too long or short and you just make up for that by drilling the hole for your pivot bushing in the correct location. With the billet plugs you simply cut the front and rear tubes of the gear leg to the exact same length every time and drop this plug in which locates the pivots (or gear leg tops) in the same spot every time. Much more precise.

    The second reason for it is strength like mentioned. First, down on the axle, the normal method is to just fishmouth the end of the axle and weld a doubler on each side. The steel fork plug at the axle where the shock strut attaches is much thicker and sleeved inside the already doubly thick axle which not only stiffens the axle in the critical junction where the tubes meet it but also creates a much more precise and stronger shock strut attach point. On the gear leg tops the difference in strength comes from fully supporting the bushing along it's entire length as well as not stressing the gear leg tube by cold or hot forming it from its original shape. If you're taking a rolled tube and then forcibly forming it back into itself then welding it that is naturally not as strong as simply welding a plug into the end of a tube that has a straight cut across its end. Like I previously touched on too, the pivot where the gear bolts ride is fully supported along its entire length instead of riding in a thin steel tube bushing that is only welded/supported on each end.

    I don't have numbers to support it being stronger (not an engineer, just a sales guy) but I can't see a reason why it wouldn't be after all it is a fair bit more material in all locations than on other landing gear designs that I've seen.
    Last edited by Crash, Jr.; 08-13-2020 at 10:24 AM.

  7. #47
    www.SkupTech.com mike mcs repair's Avatar
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    Need advice on new landing gear please

    Quote Originally Posted by Steve Pierce View Post
    Do you have some test data that the solid plug gear is stronger? How long has it been used?

    My understanding was it was done to save build time. I have not picked up a wreck where the fitting of the gear broke, usually the tubing folded somewhere and not a result of weak gear but usually terrain, pilot error or corrosion.
    Never seen a failure at top before. Other than ripping the ears off fuselage. Always mid tube failure

    Was not impressed with the air frames solid ends. Lazy design and extra weight, no advantage, itís a disadvantage


    Sent from my iPhone using SuperCub.Org mobile app

  8. #48
    Steve Pierce's Avatar
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    Quote Originally Posted by Crash, Jr. View Post
    I can assure you that milling major pieces out of a block of steel then welding them in place and welding a strap over top is far more time consuming that beating the end of a tube together and seam welding it.

    There's a couple reasons for the steel plug method, the first is accuracy. When building the way other manufacturers do you have to cut the tube overly long then fold the top together. This is largely done by eye and the resulting tube can be slightly too long or short and you just make up for that by drilling the hole for your pivot bushing in the correct location. With the billet plugs you simply cut the front and rear tubes of the gear leg to the exact same length every time and drop this plug in which locates the pivots (or gear leg tops) in the same spot every time. Much more precise.

    The second reason for it is strength like mentioned. First, down on the axle, the normal method is to just fishmouth the end of the axle and weld a doubler on each side. The steel fork plug at the axle where the shock strut attaches is much thicker and sleeved inside the already doubly thick axle which not only stiffens the axle in the critical junction where the tubes meet it but also creates a much more precise and stronger shock strut attach point. On the gear leg tops the difference in strength comes from fully supporting the bushing along it's entire length as well as not stressing the gear leg tube by cold or hot forming it from its original shape. If you're taking a rolled tube and then forcibly forming it back into itself then welding it that is naturally not as strong as simply welding a plug into the end of a tube that has a straight cut across its end. Like I previously touched on too, the pivot where the gear bolts ride is fully supported along its entire length instead of riding in a thin steel tube bushing that is only welded/supported on each end.

    I don't have numbers to support it being stronger (not an engineer, just a sales guy) but I can't see a reason why it wouldn't be after all it is a fair bit more material in all locations than on other landing gear designs that I've seen.
    Jr, I would suggest you go down to Atlee's and get Kracke to show you how they build their gear. It is a lot more involved than your description. There is a fitting 30361 in each end, each tube is precisely cut (using a pattern) and then heat formed around that fitting and then the gussets are cut, tacked and heat formed around that fitting and then welded. Way easier to program a CNC machine to spit out plugs, cut the tubes to length, insert the plugs and weld around them and then add the gussets. Labor (time) is money and I believe the way y'all do it is way faster and less time consuming than the old way. The slide I showed with the strength shows the results of the FAA's engineering tests on gear strength, whatever criteria they used. I don't see there being a big difference between the two, I do know from previous research that a 1.5" piece of 4130N tubing with a .125" wall thickness is almost twice the bending strength as a 1.25" piece the same thickness. Haven't been able to find the chart I use to use for that. I am glad every one has had good alignment with Airframes gear, maybe they changed something. No one has been able to verify that for me. I was posting my experience along with a few others thus the pictures with the lazers. If I post something here it is something I have experienced, take it for what it is worth or throw it away. Just sharing my experience to save others frustration. And I don't just post here to bash someone, if I post an experience here you can bet money I have spoken to the vendor about it. Be it Dakota Cub, Univair, Airframes or Cub Crafters. Call them and ask them, they all know me.
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    Steve Pierce

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  9. #49
    Crash, Jr.'s Avatar
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    Yeah I know, I've seen that same old slide recycled for years up to and including this years FAA safety seminar. Those "comparisons" are based on axle yield strengths and are a simple calculation based on tensile strength of their respective tube diameters and wall thicknesses. Not exactly "scientific" stuff from the FAA and it doesn't take into account any other parts of the landing gear, only the axle itself.

    I think we all wish it were only as easy as a CNC machine "spitting out" gear leg parts. A machinist would have a field day explaining the complexities of programming, zeroing tools, setting up repeatable fixtures, moving the same part 2 or 3 times to reach all areas, and how difficult it is to cut an accurately round part that will fit exactly into an imprecise tube with minimal clearance. Plus don't forget the cost of steel billet and the amount of material waste that is all part of the cost. It's not a cheap process I'll tell you that.

    I'll take your advise and check out Atlee's process. Sounds interesting. You're not wrong on very many things and yes, I'm sure my description of Atlee's process is a little over-simplified but the point is that the solid billet ends are stronger. Stronger in a meaningful way? Probably not. Like I said before, you can make something so strong that the failure point moves up into a different area so any further strength there is meaningless.

    But...it is stronger....
    Last edited by Crash, Jr.; 08-13-2020 at 06:42 PM.

  10. #50
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    Forgot to include these.
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    Steve Pierce

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  11. #51
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    Quote Originally Posted by Crash, Jr. View Post
    Yeah I know, I've seen that same old slide recycled for years up to and including this years FAA safety seminar. Those "comparisons" are based on axle yield strengths and are a simple calculation based on tensile strength of their respective tube diameters and wall thicknesses. Not exactly "scientific" stuff from the FAA.

    I think we all wish it were only as easy as a CNC machine "spitting out" gear leg parts. I'll have to run that one by the machinist, I'm sure he'll have a laugh.

    I'll take your advise and check out Atlee's process. Sounds interesting.
    Take some pictures of the process. I remember seeing a bin full of them the last time I was there. I realize it takes several process to get the finished part but I still think it saves time to manufacture that way vs the way Piper did it.
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    Sooooooooooo in that chart comparing the different gear what was the failure point??? Was it the tubes because I believe both inch and a quarter and inch and a half gear use the same down tubes or was it the axle and in reference to Mikeís post it was very common in the past to put it in internal sleeve. Most of the aircraft that come in under a helicopter seem to have a to Bent mid gear. I run inch and a quarter gear mostly because thatís the wheels I had when I got the cub and it was 5 pounds lighter. The benefit of inch and a quarter gear is it fits most of the hydraulic wheel skis on the market with no issues. No real answers just more questions!
    DENNY

  13. #53
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    It wasn't a physical test to failure. It was a simple mathematical model of the axle based on the bending strength of 4130 of the same outer diameter and wall thickness of the axle specifically. Does not take into account the gear leg tubes.

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    Geez, some guys will argue about anything. Atlee invented 3" ext HD gear. Lee Budde pretty much copied it. The new Airframes has refined it. It's all good. I've had all three so my comment comes from experience. Get out of the certificated rut and explore the good stuff!
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  15. #55
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    Couldn't agree more. Both Atlee and Airframes gear legs and pretty much any heavy duty gear leg out there is far stronger than is actually needed so arguing about the minute differences in strength or weight is certainly splitting hairs. All the gear failures I've seen are from situations in which no gear leg would survive regardless of brand in in all those cases the fuselage and gear fittings were bent/damaged as well.

    Honestly I really like the Javron gear legs that I got with my experimental cub project. Jay makes a leg that is not only very strong and beautifully made but also way lighter than other gear. Experimental is definitely the way to go.
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    Back to the OP’s question: if he wants to do beachcomber work, I would have thought the 3inch extension and ensuring heavier tail, would been a good option over STD?

  17. #57
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    Sorry but I don't see any arguing. Jr posted some statements and I asked about it. He posted some statements about construction that my experience disagree with. My main issue is the alignment concern in the PDF that no one has been able to tell me if jigs have changed etc. The way I look at it if you don't want to read about it it is kinda like a TV, there is an OFF switch. I took my questions to a PM since it is so offensive.
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  18. #58
    Steve Pierce's Avatar
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    Honestly I really like the Javron gear legs that I got with my experimental cub project. Jay makes a leg that is not only very strong and beautifully made but also way lighter than other gear. Experimental is definitely the way to go.
    What is different about Jay's gear? I have seen it but did not notice.
    Steve Pierce

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    Quote Originally Posted by Crash, Jr. View Post
    Honestly I really like the Javron gear legs that I got with my experimental cub project. Jay makes a leg that is not only very strong and beautifully made but also way lighter than other gear. Experimental is definitely the way to go.
    Funny you say that. When Mike and I first handled my Backcountry gear we both thought it was too light. That's when I drove around the corner and bought Airframes gear!
    Last edited by stewartb; 08-14-2020 at 09:55 AM.

  20. #60
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    Quote Originally Posted by Steve Pierce View Post
    What is different about Jay's gear? I have seen it but did not notice.
    Just mainly the weight and build quality. His welds are (and I say this begrudgingly) right up there with Airframes weld quality. That's mainly aesthetics though.

    I really really like the weight of them. They are on my arm scale probably around 3lbs per leg lighter than Airframes gear. I don't think they are "heavy duty" but IMO if you don't build a heavy plane that is putting a lot of force into the gear then you don't need heavy duty gear. Look at how many J3's have been bounced up and down hard surface runways for 70 years and their gear is still intact.

    And they are built just like Atlee gear with the tops folded in and bushed so obviously of a superior design so you'll probably like that Don't worry I'm not offended and I appreciate the PM. I'm just proud of the company I work for and the parts they make so my experience is a little different than yours.

  21. #61
    Steve Pierce's Avatar
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    Quote Originally Posted by Crash, Jr. View Post

    And they are built just like Atlee gear with the tops folded in and bushed so obviously of a superior design so you'll probably like that Don't worry I'm not offended and I appreciate the PM. I'm just proud of the company I work for and the parts they make so my experience is a little different than yours.
    I think you misinterpreted what I posted. I believe Airframes machined lugs are stronger, what I disagreed with was
    I can assure you that milling major pieces out of a block of steel then welding them in place and welding a strap over top is far more time consuming that beating the end of a tube together and seam welding it.
    I believe it takes more time to build them the way Piper did and Atlee do it.
    Steve Pierce

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