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Need advice on new landing gear please

I want the prop clearance. I would be curious how much more weight the 3" extended gear puts on the tail. I doubt it is much.

Here is a quick way to find out......

Assuming the 3” gear raises the aircraft by the previously stated 1.5”, put a 1.5” block under the tailwheel and measure the decrease in tailwheel weight. It should be roughly equal to the increase in weight resulting from increasing the gear height.

Jeff


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I'd advise you go back and change your order to 3" extended. The 3" gear may not be "necessary" to your buddy but it does help when you're really dragging the plane in for 3 point landings. IMO it's a no brainer to go 3" extended even with Bushwheels. Heck, every single person I know has 3" gear on their cub; it's almost the new standard for PA-18's in Alaska. 3" gear, 31's and a borer prop minimum.

you don’t need 3” gear unless you are running skiis in the winter... 31’s and standard heavy duty is a nice setup.
 
The difference in lift-off speed is really dramatic between the Cub I fly and a stock Cub on short gear and 8.00 tires. For getting in and out short AOA is critical unless you have Keller flaps. On 35s with 3" gear and extra AOI I can still touch the tailwheel on rotation and the plane will fly off at a very low airspeed. Also helps put in on the mains slow at touchdown.

I destroyed a set of early TK1s doing something stupid (safety cables hit the limit) and the Javron 1.5" HD gear survived unscathed, to Tony's utter disbelief.

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Everything I have seen shows 1 1/2" being considerably stronger that 1 1/4". Just look at .125" tube specs in each size.
Yep. A few years ago I compared the bending strength of 1 1/2 round tube with 1/8 wall to 1 1/4 solid round. The 1 1/2 was computed to be stronger. I was amazed. It did not take into account the possibility of crushing, but still - - -
 
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Originally Posted by Crash, Jr.

Atlee 3" gear is great too and ever so slightly lighter but also every so slightly not as strong. Strength is relative and for 99% of people any modern PA-18 gear is plenty strong.




Not according to the tests the Anchorage ACO did. Do you get the alignment issues squared away on your gear?

Junior, Has Airframes addressed these alignment issues?
 
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Originally Posted by Crash, Jr.

Atlee 3" gear is great too and ever so slightly lighter but also every so slightly not as strong. Strength is relative and for 99% of people any modern PA-18 gear is plenty strong.






Junior, Has Airframes addressed these alignment issues?
You keep beating this horse- how recently have you had all these issues- I’ve installed several new sets of their gear legs over the last few years and never had any alignment or fitment issues with them...
 
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You keep beating this horse- how recently have you had all these issues- I’ve installed several new sets of their gear legs over the last few years and never had any alignment or firmest issues with them...
That is why I keep asking the question that no one can answer after several phones calls over the last several years to no avail.
 

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Originally Posted by Crash, Jr.

Atlee 3" gear is great too and ever so slightly lighter but also every so slightly not as strong. Strength is relative and for 99% of people any modern PA-18 gear is plenty strong.






Junior, Has Airframes addressed these alignment issues?

Steve, I've been kind of avoiding answering your question directly on here because I'm not on here to represent Airframes. It's just me on my personal time trying to learn about cubs and contribute the best I can in areas in which I have some knowledge. If you or anybody has Airframes related questions feel free to send me a PM or call during business hours.

Short answer: no, Airframes has not done anything different with the landing gear. Just like with Atlee or Univair they are built in jigs that are conformity checked bi-yearly for alignment. Tops are pinned in place in the jig in alignment with one another. Landing gear legs do some crazy things when you weld the vee at the axle but the tops have bushings pressed in and are line reamed during final assembly to ensure best alignment.
 
Steve, I've been kind of avoiding answering your question directly on here because I'm not on here to represent Airframes. It's just me on my personal time trying to learn about cubs and contribute the best I can in areas in which I have some knowledge. If you or anybody has Airframes related questions feel free to send me a PM or call during business hours.

Short answer: no, Airframes has not done anything different with the landing gear. Just like with Atlee or Univair they are built in jigs that are conformity checked bi-yearly for alignment. Tops are pinned in place in the jig in alignment with one another. Landing gear legs do some crazy things when you weld the vee at the axle but the tops have bushings pressed in and are line reamed during final assembly to ensure best alignment.
I have, from the bottom up over the years. Heather said they were aware and that they were working g on it and she wanted me to come up and see what they were doing. Shortly after that she left so that was the end of that.

I have jigs to rebuild Short Wing and Cub gear as well as fuselage jigs along with other components so have some experience with how stuff can move.

Curious about your comment about Airframes gear being slightly stronger than Atlee's?
 
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.
 
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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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...
 
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.
 
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...

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.
 
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.
 
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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, it’s a disadvantage


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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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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....
 
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Forgot to include these.
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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.

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.
 
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 Mike’s 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 that’s 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
 
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.
 
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! :)
 
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.
 
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?
 
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.
 
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.
 
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!
 
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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.
 
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