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Gear swap... Number 3...Bush Gear part deux

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Posted

Some of you know the story for those that don't.. yes I went from Stock Avid Gear with mechanical brakes to Kitfox Bungee gear to Airdale "Bush" gear back to Kitfox Bungee gear and now I'm going back to the second addition Airdale Bush gear. All of these swaps were simply upgrades until my first set of Airdale Bush gear. I was super happy with it for about 50 landings on all sorts of stuff. Last June a long ways from home. I made a rough uphill off airport landing and it folded up on me. Luckily I had no fuse damage, prop strike, or wingtip damage. I was damn lucky and was able to get my plane flying on my old bungee gear with a field fix.  I just received the version 2 gear from Brett recently and I wanted to show you guys what changes have been made. While it took a long time I have to give Kudos to Brett for filling my order and making the changes we talked about over the phone.

 

The Box

 

IMG_5558-1.jpg

 

Bracing in the middle and new step. New legs are .049 tubing vs -035.

 

IMG_5559-1.jpg

 

Old springs side by side with new springs... My first set had NO travel... Hoping this one does.

 

photo8-1.jpg

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Posted

I plan on using the same gear ,please let us know how it works for you.

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Posted

Thanks for the update Joey.  I noticed that you did not show the cabane (vee), was anything done to it to beef it up in the new version?  Also was your first set of springs the yellow ones?  I have the Highwing version and it shipped with the yellow springs.  It did settle about 5/8" when the weight of the plane was on it but seemed somewhat stiff.

Paul 

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Posted

Paul when compare to my buddies set side by side the V was identical. What I posted was the only changes we noticed. Frankly after hearing about all the mangled fuses lately I don't think you want it much stronger or the next weaker area is going to bend. On my first set the front leg on one side folded right in the middle. Hopefully these changes will fix that issue. My first set had the yellow springs like my buddies on the blue set in the picture. I didn't think they rode too stiff when landing or taxiing but with no travel if you prang one in something is going to give! These ones supposedly have around 3" of travel.

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Posted

Thanks Joey, will you please measure the springs wire height and width while you have it apart. I am interested in hearing how the new spring works out.

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Posted

Joey from looking at the picture is appears that there is about the same amount of slot as the original.  I did some rough figuring today and came up with a total axle movement of about 3" with the 21/2" inch slot that mine has (HighWing). Mine settled about 1/2" with the empty weight plus about 10 gal of fuel (about 675#) so down and dirty math leaves me with about 2 1/2" of travel at the axles....so I guess that I will be interested in hearing how much yours travels with just the empty weight.  I'll go back to the hanger this afternoon and see if I can get some better figures and also check to see what the axle travel is on the original bungie  gear.  OK, not sure if all of this has any great value by way of comparison, an engineer could do a much better job of it I am sure but then the newtons, ergs and such just makes my head hertz.

 

Snowing here in Wyoming

Paul

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Posted

Paul the thickness of the spring is 7mm I couldn't get a width as the cabane is assembled. I tried to get the upper bolt out but the spring must be compressed some putting pressure on it.

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Posted

I hate to jump in here, because I barely know what I'm talking about. However, I've been working with a guy to build a cabane style gear for my Magnum. The biggest issue we ran into was the fact that the axle is so far forward of the first gear mount. On the Magnum it is about 6" forward of the center of the front mount. This means the cabane V and suspension legs have to be angled about 10 degrees. Normal cabanes, cub style, are perpendicular to the bottom longerons, with the axle being directly below the front mount. The cubs have a new STC that allows them to add a new gear that moves the axle 3" forward of the front mount. When they did this they used urethane bushings at the cabane V/suspension leg attach point to allow the extra movement that happens when the geometry is not normal (axle and front mount perpendicular to bottom longeron).

I'm sure that is clear as mud...but here is my question...does the Airdale bush gear have urethane bushings at the cabane V lower attach points? I believe most of the Avids axles are 3"-4" forward of the front mount...Right?

Evidently, when the axle is moved forward, during landings and especially if side loads are involved, the suspension leg has rotational forces applied to it, that is why the urethane bushings are there...to give the joint the freedom to move.

So, if the urethane bushings aren't there, the connection at the V would be too rigid causing tubing to bend at the weakest point.

This is secondhand knowledge, with my limited comprehension, from an engineer. So take it with a grain of salt...

I wonder if this is causing some of the issues?

Ron

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Posted

Do you by chance have any pictures of the urathane bushings and how they fit in where they do? Dosen't the Highlander use a three legged gear? I wonder if that is why? Questions, questions.... Thanks, Jim

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Posted

Jim,

I just searched the Internet and couldn't find any pics that showed urathane bushings. My info is second hand, but it is from a guy that builds Cub and Supercub landing gear for a living. I'll ask him again so I'm sure I'm not giving you bad info...

If you look at a Cub/SCub gear their cabane V attaches to a bracket inboard of the front gear mount...the Airdale bush gear attaches around the front mount with the same bolt the gear leg uses...Right? This could be another cause of the bending. I base this on a service bulletin from Cub Crafters, where they call for the use of thicker brackets to be used. Evidently, they were having problems with hard, one wheeled landings bending the brackets and sending the force of the landing through the airframe and bending other tubes in the frame.

I'm not dogging the Airdale Bush Gear...I'm just pointing out some things I'm running into while trying to build a new gear for my Magnum. The Airdale Bush Gear won't fit my Magnum or I would have put it on already and you would have never seen all of the BS above. I believe all Avids (except the Magnum) have a low enough gross weight that you could use a shopping cart for a landing gear and it will work on a real landing strip. However, if you take your Avid and use it like a bush plane, you should probably make that shopping cart look like a bush plane's gear...right? I think the Airdale gear is a good, quick to install, inexpensive, taller and wider gear. Hell, it makes our planes look like they should. However, I think calling it a Bush Gear almost sets us up for failure...

I'm sure the AK fellas on here know more about this than I do. SuperAvid designed his own bungee gear with a third attach point for some of these reasons.

Just my opinions, and they can change,

Ron

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Posted

This project got put on the back burner but I recently have gotten back to it and I've gotten a few inquiries on the TK1 Gear so I thought I would do an update. Here are couple pictures of the cabane that will replace the die springs that Kitfox/Avid/Highwing sell with their "Bush Gear". It's spendy...I'll leave it at that. These are a 4" stroke and weight approx 5 lbs more than the metal springs. Contact Tony at TK1Racing.com for more details.

 

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Nickel finished...unlimited valving options on the shocks depending on your weight

 

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The reason I am doing this is I ran the Avid gear once before and well...lets just say it's not on my plane now. The metal springs are just not enough travel if you plan to really do any bush work unless your running 31" tires. I included this pic so you get an idea on just how much bigger this gear is over the over the stock bungee gear. The tires are the 21" Nancos on Kitfox 8" Douglas wheels.

 

IMG_4586.jpg

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Posted

 

The reason I am doing this is I ran the Avid gear once before and well...lets just say it's not on my plane now. The metal springs are just not enough travel if you plan to really do any bush work unless your running 31" tires. I included this pic so you get an idea on just how much bigger this gear is over the over the stock bungee gear. The tires are the 21" Nancos on Kitfox 8" Douglas wheels.

What was your net weight gain switching from the stock gear to this set?

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Posted

Prob around 10lbs. The 27" Dessers added some weight too. I gave up on weight and balance 6 years ago. It's a beast now. Truly a flying ATV.

 

image.jpeg

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Posted

 I really like the TK1 gear. what gear did you use to put the TK1 on?

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Posted

My Gear was built at Airdale a few years ago. He is no longer doing business but Avid was recently purchased and we should hopefully start seeing parts again soon. We had to modify the Gear legs to accept the TK1 set up but it was not too difficult.

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Posted (edited)

My Gear was built at Airdale a few years ago. He is no longer doing business but Avid was recently purchased and we should hopefully start seeing parts again soon. We had to modify the Gear legs to accept the TK1 set up but it was not too difficult.

ahhh that's unfortunate. Not much to choose from when it comes to Bushgear. Unless you order from Kitfox and it is EXPENSIVE! I talked to the TK1 guys about modifying my current gear, but I'm just not too sure what the final product would look like. I like the clearance you have on yours. Putting the shocks on my bird might be a little bit like putting lipstick on a pig but in my mind I feel like it would make for a safer airplane. I guess that's just my justification of spending the money on it. 

Edited by Durham66

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